Geotechnical Engineering Study Report

Transcription

1 Geotechnical Engineering Study Report The report has been prepared for use in developing an overall design concept. Paragraphs, statements, test results, boring logs, diagrams, etc., should not be taken out of context, nor utilized without a knowledge and awareness of their intent within the overall concept of the report. Statements, conclusions, and recommendations in the report are directed to the Owner and the Owner s design engineers, and not to bidding contractors. The context of the statements, conclusions, and recommendations have been conveyed to the Owner and the Owner s design engineers through various meetings, correspondence, and shall not be interpreted by bidding contractors to have singular meaning or interpretation for bidding purposes. The report was made for design purposes only and verification of the subsurface conditions for other purposes including, but not limited to determining difficulty of excavation, traffic ability, suitability of on site soil materials or quantities, etc., is the responsibility of bidding contractors.

2 GEOTECHNICAL STUDY CLEARFORK MAIN STREET BRIDGE FORT WORTH, TEXAS SUBMITTED TO FREESE AND NICHOLS, INC INTERNATIONAL PLAZA, SUITE 200 FORT WORTH, TEXAS BY HVJ ASSOCIATES, INC. JANUARY 19, 2009 REPORT NO. DG

3 January 19, 2009 Mr. John F. Dewar, P.E., S.E. Freese and Nichols, Inc International Plaza, Ste. 200 Fort Worth, Texas Re: Geotechnical Investigation Clearfork Main Street Bridge Fort Worth, Texas Owner: City of Fort Worth HVJ Project No. DG Dear Mr. Dewar: Submitted herein is the report of our geotechnical investigation for the above referenced project. The study was performed in accordance with our proposal number DG dated February 18, 2008 and is subject to the limitations presented in this report. We appreciate the opportunity of working with you on this project. Please read the entire report and notify us if there are questions concerning this report or if we may be of further assistance. Sincerely, HVJ ASSOCIATES, INC. Texas Firm Registration No. F Fadi N. Faraj, P.E. Senior Project Manager FF/DK 01/19/2009 Copies submitted: 4 Hard Copies + 1 Electronic Copy The seal appearing on this document was authorized by Fadi Faraj, PE on January 19, Alteration of a sealed document without proper notification to the responsible engineer is an offense under the Texas Engineering Practice Act. The following lists the pages which complete this report: Main Text 19 pages Plates 18 pages Appendix A 11 pages

4 TABLE OF CONTENTS 1 EXECUTIVE SUMMARY... I 2 INTRODUCTION General Geotechnical Study Program FIELD EXPLORATION General Sampling Methods Groundwater Observations LABORATORY TESTING SITE CHARACTERIZATION General Geology Soil Stratigraphy Groundwater BRIDGE FOUNDATION RECOMMENDATIONS General Foundation Drilled Shaft Axial Capacity Lateral Capacity Group Effects Settlement Drilled Shaft Construction Recommendations RETAINING WALL RECOMMENDATIONS General Lateral Pressures on Retaining Walls Bearing Pressure, Sliding and Overturning Mechanically Stabilized Earth Retaining Walls GLOBAL STABILITY General Retaining Wall Global Stability Results Embankments Slope Stability Results EMBANKMENT SETTLEMENT ANALYSIS General Fill Settlement Foundation Settlement Abutment-Interior Bent Differential Settlement Bridge Abutment to Embankment Differential Settlement PAVEMENT DESIGN RECOMMENDATIONS General Rigid Pavement Section Rigid Pavement Thickness and Load Capacity Preparation of Subgrade...12 Page

5 11 SITE PREPARATION DESIGN REVIEW LIMITATIONS...13 PLATES Plate SITE VICINITY...1 GEOLOGY MAP...2 PLAN OF BORINGS...3 BORING LOGS KEY TO TERMS AND SYMBOLS...11 & 12 APPENDICES Appendix GLOBAL STABILITY ANALYSIS...A

6 1 EXECUTIVE SUMMARY HVJ Associates, Inc. was retained by Freese and Nichols, Inc. to perform a geotechnical investigation for the proposed Clearfork Main Street Bridge crossing USACE channel in Fort Worth, Texas. We understand that the total length of the proposed bridge is about 1,100 feet. The purpose of this study is to provide design and construction recommendations for deep foundations for the proposed bridge, as well as recommendations for the proposed embankment. Subsurface conditions were evaluated by drilling and sampling a total of seven (7) borings. Two roadway borings were drilled to a depth of 15 feet and five bridge borings were drilled to a depth of 60 feet below the existing grade. A brief summary of the investigational findings are as follow: 1. Based on our field investigation, the subsurface soils are presented below: Roadway Borings (R-1 and R-2): The subsurface soils at the site generally consist of firm to hard sandy lean clays to the termination depth of 15 feet in boring R-1 and to a depth of about 12 feet in boring R-2, followed by very loose clayey sands to the termination depth of 15 feet below ground surface. Bridge Borings (B-1 though B-5): The subsurface soils at the site generally consist of firm to hard sandy lean clays in the upper 12 to 20 feet, followed by limestone to the termination depth of 60 feet below ground surface. Very loose to dense clayey sands were encountered at a depth of about 12 feet in boring B-2 and at a depth of about 13 feet in boring B-5. Weathered limestone was encountered in boring B-2 at a depth of about 21 feet. Clayey gravels were encountered at a depth of about 18 feet in boring B During the drilling operations groundwater was encountered in borings R-2, B-3, B-4 and B-5 at a depth below the ground surface of 12, 22, 8 and 21 feet, respectively. It should be noted that groundwater levels determined during drilling may not accurately reflect the true groundwater conditions, and therefore should only be considered as approximate. It should also be noted that groundwater levels might fluctuate seasonally and with climatic conditions. 3. We recommend using straight shaft penetrating to a minimum depth of three shafts diameter or 10 feet into the intact limestone. An allowable end bearing of 30 tsf and allowable skin friction of 3.0 tsf in the limestone can be used. Intact rock was encountered below depth 25 feet below existing ground surface in borings B-1 through B-3, below depth 30 feet in boring B-4, and below depth 45 feet in boring B Our calculations indicate that the proposed retaining walls meet the recommended factors of safety for bearing, sliding, and overturning except for retaining walls ranging in height between 20 to 30 feet on the southeast side of the bridge (Close to B-5). At these locations we recommended extending the reinforcement straps to be equal to the full wall height instead of 0.7 times the wall height. 5. We have performed global slope stability analysis based on the proposed cross sections. Our calculations indicate that the retaining walls meet the recommended factors of safety for short term and long term stability. The factor of safety for the global slope stability of the MSE walls was calculated as 2.32 for the short term loading condition and 1.37 for the long term loading condition. i

7 6. Consolidation settlements of the natural soil beneath the embankment and retaining wall were estimated at the corner and along the edge of the retaining wall for the full embankment height to investigate retaining wall differential settlement. Our calculations indicate an estimated settlement at the edge of the retaining wall of 2.2 inches, and at the corner of the retaining wall of 1.3 inches. The estimated differential settlement of the wall at the abutment is 0.9 inches. 7. The following table summarizes the pavement design thickness recommendations: Street Classification Collector with 100,000 annual ESAL, 1.5% growth rate, and 25 years design life Four-lane Collector with 200,000 annual ESAL, 2.0% growth rate, and 30 years design life Arterial with 300,000 annual ESAL, 3.0% growth rate, and 30 years design life Minimum Recommended Concrete Pavement Thickness (in) Please note that this executive summary does not fully relate our findings and opinions. These findings and opinions are only presented through our full report. ii

8 2 INTRODUCTION 2.1 General HVJ Associates, Inc. was retained by Freese and Nichols, Inc. to perform a geotechnical investigation for the construction of a bridge along Stonegate Boulevard to cross USACE channel in Fort Worth, Texas. The purpose of this study is to provide design and construction recommendations for deep foundations for the proposed bridge. We understand that the total length of the proposed bridge is about 1,100 feet. A site vicinity map is presented on Plate Geotechnical Study Program The primary objectives of this study were to gather information on subsurface conditions at the project site and to develop design and construction recommendations for the proposed foundations. The objectives were accomplished by: 1. Drilling seven (7) soil borings to determine soil stratigraphy and to obtain samples for laboratory testing; 2. Performing laboratory tests to determine physical characteristics of the soils, and 3. Performing engineering analyses to develop design guidelines and recommendations for the proposed structure. Subsequent sections of this report contain descriptions of the field exploration, laboratory testing program, general site and subsurface conditions, design recommendations, and construction considerations. 3 FIELD EXPLORATION 3.1 General The field exploration program undertaken for the project was performed on June 17 through June 24, Subsurface conditions were evaluated by drilling and sampling a total of seven (7) borings. Two (2) roadway borings were drilled to a depth of 15 feet and five (5) bridge borings were drilled to a depth of 60 feet below the existing grade. A site plan showing the approximate boring locations is presented on the Plan of Borings, Plate Sampling Methods Samples were obtained continuously to a depth of 10 feet and at 5-foot intervals thereafter. Cohesive soil samples were obtained with a three-inch thin-walled (Shelby) tube sampler in general accordance with ASTM D-1587 standard. Granular cohesionless soils were sampled with the Standard Penetration Test (SPT) sampler in accordance with ASTM D1586 standard. Each sample was removed from the sampler in the field, carefully examined and then classified. The shear strength of the cohesive soils was estimated by a hand penetrometer in the field. Suitable portions of each sample were sealed and packaged for transportation to our laboratory. Augering was performed when rock was encountered and TxDOT cone penetrometer test was performed at approximately 5-foot intervals in the rock. The test consists of driving a 3-inch diameter cone with a 170-pound hammer, which is dropped for a distance of 2 feet. The cone is seated and driven to 12 blows or 12 inches whichever comes first. Then it is driven for two 1

9 consecutive 6-inch increments, and the blow counts for each increment are noted. In hard materials, the cone is driven with the resulting penetration in inches recorded for the 50 blows. The numbers of blows for each 6-inch increment and/or the amount of penetration for each 50 blows are presented on the boring logs presented on Plates 4 through 10. Detailed descriptions of the soils and rocks encountered in the boring are given on the boring logs presented on Plates 4 through 10. Keys to the terms and symbols used for soil and rock classification on the boring logs are also included on Plates 11 and Groundwater Observations Groundwater levels in the borings were observed during the drilling operations. The water levels measured during drilling are reported on the boring logs, which are presented on Plates 4 through LABORATORY TESTING Selected soil samples were tested in the laboratory to determine applicable physical and engineering properties. All tests were performed according to the ASTM standards. These tests consisted of moisture content measurements, Atterberg limits, percent finer than No. 200 sieve, unconfined compression (UC), and unit dry weight tests. The moisture content, Atterberg limits, and percent finer than No. 200 sieve results were utilized to verify field classifications by the Unified Soils Classification System. The unconfined compression tests were performed to obtain the undrained shear strength of the soil. The type and number of tests performed for this investigation are summarized in the following Table: Type of Test Number of Tests Moisture Content (ASTM D2216) 14 Atterberg Limits (ASTM D4318) 5 Percent Passing No. 200 Sieve (ASTM D1140) 6 Hand Penetrometer 9 Unconfined Compression (UC) (ASTM D 2166) 2 Unit Dry Weight (ASTM D 2166) 2 The laboratory test results are presented on the boring logs on Plates 4 through SITE CHARACTERIZATION 5.1 General Geology According to the University of Texas at Austin, Bureau of Economic Geology Geologic Atlas of Texas Dallas Sheet, the project area lies within the surface expression of Alluvium (map symbol Qal) and Fluviatile (map symbol Qt) deposits underlain by Fort Worth Limestone (map symbol Kfd) and Duck Creek Formation (map symbol Kdc). The Alluvium and Fluviatile deposits mainly consist of flood-plain deposits including gravel, sand, silt, silty clay, clay and organic matter. The Fort Worth Limestone is mainly represented by aphanitic to biosparite, burrowed limestone weathers and calcareous clay. The Duck Creek Formation consists of aphanitic and partially bioclastic, locally burrowed limestone and weathers. Geology map is presented on Plate Soil Stratigraphy Our interpretation of soil and groundwater conditions at the project site is based on information obtained at the boring locations only. This information has been used as the basis for our 2

10 conclusions and recommendations. Significant variations at areas not explored by the project borings may require reevaluation of our findings and conclusions. Based on our field investigation, the subsurface soils observed are presented below: Roadway Borings (R-1 and R-2): The subsurface soils at the site generally consist of firm to hard sandy lean clays to the termination depth of 15 feet in boring R-1 and to a depth of about 12 feet in boring R-2, followed by very loose clayey sands to the termination depth of 15 feet below ground surface. Bridge Borings (B-1 though B-5): The subsurface soils at the site generally consist of firm to hard sandy lean clays in the upper 12 to 20 feet, followed by limestone to the termination depth of 60 feet below ground surface. Very loose to dense clayey sands were encountered at a depth of about 12 feet in boring B-2 and at a depth of about 13 feet in boring B-5. Weathered limestone was encountered in boring B-2 at a depth of about 21 feet. Clayey gravels were encountered at a depth of about 18 feet in boring B-4. Detailed descriptions of the materials encountered in the borings are given on the boring logs presented on Plates 4 through 10. Key to the terms and symbols used for soil and rock classification on the boring logs is given on Plate 11 and Groundwater During the drilling operations groundwater was encountered in borings R-2, B-3, B-4 and B-5 at a depth below the ground surface of 12, 22, 8 and 21 feet, respectively. It should be noted that groundwater levels determined during drilling may not accurately reflect the true groundwater conditions, and therefore should only be considered as approximate. It should also be noted that groundwater levels might fluctuate seasonally and with climatic conditions. 6 BRIDGE FOUNDATION RECOMMENDATIONS 6.1 General We understand that the project involves the design and construction of a bridge along Stonegate Boulevard to cross USACE channel in Fort Worth, Texas. We understand that the total length of the proposed bridge is about 1,100 feet. 6.2 Foundation Foundations for the structure must satisfy two basic design criteria. First, bearing pressure transmitted to the foundation soils should not exceed the allowable bearing pressures computed with an adequate factor of safety. Second, foundation movement due to soil volume change must be within desirable limits. A deep foundation system will be required for foundation support. 6.3 Drilled Shaft Axial Capacity It is recommended that the proposed bridges be supported on a system of drilled straight shaft piers. Drilled shafts should be founded a minimum of three shaft diameter or 10 feet into the layer of intact limestone. Intact rock was encountered below depth 25 feet below existing ground surface in borings B-1 through B-3, below depth 30 feet in boring B-4, and below depth 45 feet in boring B-5. The piers should be sized for an allowable end bearing of 30 tsf and an allowable skin friction of 3.0 tsf in the limestone. Due to the difference in strength, the upper soils above the limestone should 3

11 be neglected in skin friction calculations. Care should be taken to terminate the shafts in an intact layer of limestone instead of the softer layers occasionally encountered. We recommend a minimum shaft penetration of three times the shaft diameter or 10 feet into the intact limestone, whichever is greater. Settlements for properly constructed drilled shafts should be less than one inch. For tension loads we recommend using uplift resistance of 2/3 rd of the allowable skin friction in the limestone (i.e. an allowable uplift resistance of 2.0 tsf in the limestone). 6.4 Lateral Capacity Foundation elements often have to withstand significant lateral loads in addition to axial loads. Wind forces on bridges are forms of lateral loading. Lateral loads on a drilled shaft will be countered by the mobilization of resistance in the surrounding soils as the shaft deflects. The lateral load capacity of the shaft, therefore, will depend on its relative stiffness, and the strength of the surrounding soils. A rational analysis of a problem involving lateral loading on a shaft must consider the interaction of the soil and the structure. Equilibrium of forces and compatibility of displacements throughout the total system are the two fundamental conditions that are to be satisfied in the analysis. If high lateral loads must be resisted with vertical shafts, a detailed study should be done to provide lateral load capacity curves. Lateral load analysis should be performed using softwares such as LPILE. 6.5 Group Effects Groups of shafts should have a center-to-center spacing of at least 2.5D when designing foundations using one row group of shafts and 3D for foundations using two or more rows of shafts where D is the diameter of the shaft. For greater spacing, the total capacity will be equal to the sum of the capacities of the individual shafts in the group. The group capacity may be less than the sum of individual capacities at closer spacing. If spacing smaller than 3D is planned, HVJ Associates, Inc. should be contacted to assess group capacity. 6.6 Settlement Movements will consist generally of elastic shortening of the shaft and soil deformation at the shaft tip. It is our opinion that shaft head settlement will be less than 1 inch at interior bent foundation locations. 6.7 Drilled Shaft Construction Recommendations Drilled shaft construction and installation should follow TxDOT Standard Specification Item 416, TxDOT Construction Bulletin C-9, and ACI Slurry displacement methods for drilled shaft construction are allowed under TxDOT Standard Specifications. Presented below are a few specific recommendations. 1. Drilled shaft excavations should be inspected for verticality and side sloughing. Verticality is specified at one inch in ten feet of the shaft length, and should be checked to the full depth of dry augering prior to introducing drilling mud. 2. Before placing concrete, the shaft bottom should be cleaned out with a drilling bucket in order to remove any sediments that may not be displaced by the concrete. The shaft bottoms should be cleaned with a "clean-out" bucket until rotation on the bottom without crowd (i.e. penetration under force) produces little spoil. Probing after clean out is essential to verify the condition of the base of the shaft. 4

12 3. Concrete placement should be accomplished as directed in TxDOT Standard Specification Item F. The tremie pipe diameter should be at least eight times as large as the largest concrete aggregate size. 4. A computation of the final concrete volume for each shaft should be made. Shafts taking an unreasonably high or low volume of concrete should be cored to check their integrity. 5. Due to the fact that clayey sand and clayey gravel layers were encountered in some of the borings at a depth ranging from 13 feet to 18 feet, and the ground water was encountered in some of the borings at a depth ranging between 8 and 22 feet, we anticipate that casing or slurry will be needed to prevent caving in. If casing is used it should be extracted slowly and smoothly with a vibratory hammer. The casing should always remain at least one foot below the level of the concrete during placement. Our analyses assume no casing will be left in place. We should be informed if casing will be left in place so we may provide revised shaft capacity calculations. 6. Shaft excavations should not be made within three shaft diameters (edge to edge) of shafts that have been concreted within the last 24 hours. 7 RETAINING WALL RECOMMENDATIONS 7.1 General Based on the information provided to us by Freese & Nichols, Inc., the maximum height of the planned mechanically stabilized earth (MSE) retaining walls will be approximately 30 feet. The retaining walls will be on-grade, and must be designed to resist lateral active earth pressures. This section describes the earth forces that must be considered when designing MSE retaining walls for overall sliding, bearing capacity, and overturning stability. For MSE retaining walls, additional design is required to determine the width and length of reinforcement strips considering such factors as the spacing between reinforcing strips and the material used to construct the strips. The MSE retaining wall subcontractor typically carries out such design. 7.2 Lateral Pressures on Retaining Walls The pressure which soil can be expected to exert on a retaining wall is mainly a function of the type of backfill and its method of placement. Over-compaction of backfill behind walls and utilization of highly plastic expansive clay backfill are practices that generally produce the highest wall pressures and should be avoided. In these conditions horizontal earth pressures exceeding the vertical earth pressure can be expected. Backfill selection and method of placement are critical design assumptions for the retaining walls. Design lateral pressures for retaining walls may be calculated for each backfill type using the following equivalent fluid densities for drained level backfill shown in the Table 7-1 below: 5

13 Table Lateral Earth Pressure of Retaining Wall Backfill Equivalent Fluid Fill Type Density (pcf) Type A or Type D Backfill 45 Type C Backfill 65 TxDOT allows the use of Type A or Type D backfill behind the retaining wall in accordance with Item 432. Type D is intended for use in MSE walls that are subjected to inundation. The effects of traffic loads can be treated as an additional two feet of equivalent fluid extending above the top of the wall. For cases where an embankment is placed above the top of the wall, lateral pressures should be calculated assuming an equivalent fluid density 15 pcf higher than that quoted in the above table for slopes no steeper than 3(H):1(V). In addition to the higher lateral pressure, a vertical load is applied to the back of the retaining wall due to the presence of the slope. This vertical force may be calculated assuming 10, 20 and 40 pounds per foot of wall height per foot of wall width that are developed in bank sand, select cohesive and on site cohesive soils, respectively, for slopes no steeper than 3(H):1(V). 7.3 Bearing Pressure, Sliding and Overturning Mechanically stabilized earth retaining walls require stability evaluation for bearing pressure, sliding and overturning. The following table summarizes the minimum recommended factors of safety for bearing pressure, sliding and overturning. Table 5-2 Minimum Recommended Factors of Safety Stability Condition Minimum Factor of Safety Recommended Bearing pressure 2.0 Sliding 1.5 Overturning 2.0 We have evaluated the factors of safety for the retaining walls based on the available cross sections and the results are summarized in the Table 7-3. Table 7-3 Calculated Factors of Safety Computed Factor of Safety Wall Location Wall Height (ft) Soil Shear Strength at Foundation Depth (psf) Bearing Pressure Sliding Overturning Northwest Side (Close to B-1) Southeast Side (Close to B-5) Up to Up to

14 Computed Factor of Safety Wall Location Wall Height (ft) Soil Shear Strength at Foundation Depth (psf) Bearing Pressure Sliding Overturning Southeast Side (Close to B-5) 20 to * * Indicates lower than recommended factor of safety Our calculations indicate that the proposed retaining walls meet the recommended factors of safety for bearing, sliding, and overturning except for retaining walls ranging in height between 20 to 30 feet on the southeast side of the bridge (Close to B-5). At these locations we recommended extending the reinforcement straps to be equal to the full wall height instead of 0.7 times the wall height. 7.4 Mechanically Stabilized Earth Retaining Walls Mechanically stabilized earth retaining walls require detailed design related to the configuration of reinforcement within the stabilized backfill. The MSE wall subcontractor generally performs such design. Backfill material and construction for the MSE wall should be in accordance with Item of TxDOT Standard Specification. TxDOT allows the use of Type A or Type D backfill behind the retaining wall in accordance with Item 432. Type D is intended for use in MSE walls that are subjected to inundation. Leveling pads for MSE retaining walls should be constructed at least two feet below the lowest adjacent finished grade. The contractor should check the reinforcing strip design for safety against strip breakage, strip adherence, and strip corrosion. MSE retaining walls should be designed in accordance with TxDOT Standard Drawing No. MSE(RW). The stabilized mass width shown on the standard drawing should be considered a minimum value and does not relieve the contractor from his responsibility to check the reinforcing strip length required to ensure a stable wall. Embankment fill retained by MSE retaining walls is typically specified as Type C fill in accordance with TxDOT Standard Specification Item GLOBAL STABILITY 8.1 General Several methods of slope stability analysis are available. We used Bishop s circular to calculate the factor of safety against instability for the MSE walls and sloped embankments. Bishop s circular method was used when a uniform clay layer existed beneath the MSE wall. Slope stability analyses were conducted using a microcomputer version of WINSTABL2 slope stability program that calculates the factor of safety against slope failure using a two-dimensional limiting equilibrium method. Critical failure surfaces generated by this software as well as output files are presented in Appendix A. The TxDOT Geotechnical Manual requires a minimum factor of safety of 1.3 for rotational stability. The factors of safety represent the calculated resisting forces and moments divided by the calculated driving forces and moments of the various potential failure surfaces analyzed. These forces and moments are based on the estimated unit weights and shear strengths of the various soils in the slope profile. Accordingly, a factor of safety of 1.0 indicates impending failure. The larger the 7

15 factor of safety above 1.0 the lower the risk that the slope will fail. As a practical matter, and in consideration of the variables and unknowns involved, the risk cannot be reduced to zero. The goal is to reduce the risk of slope failure to a reasonable and acceptable level, with due consideration of the consequences of failure. Global stability analyses were performed for the end of construction case and long-term case for embankments. Since flooding of the embankment is not anticipated, rapid drawdown case was not considered. The soil parameters used in each case are discussed below and were estimated based on the field and laboratory data developed for this investigation. End of Construction. The end of construction case models the initial undrained condition of the soil. For this analysis, unconsolidated undrained soil parameters were used. The soil parameters used in the analysis of the slope stability analysis for this condition are presented in Appendix A. Long Term. The long-term design case represents steady state piezometric and stress conditions. When embankment is constructed, altered stress conditions create pore pressure changes and the undrained strength of the embankment soils is mobilized. After time, these pore pressures drain and drained shear strength conditions govern the embankment global stability. Long-term effective soil parameters used for this model are presented in Appendix A. 8.2 Retaining Wall Global Stability Results We have performed retaining wall global stability analysis based on the proposed cross sections. Our calculations indicate that the retaining walls meet the recommended factors of safety for short term and long term stability. The factor of safety for the global slope stability of the MSE walls was calculated as 2.32 for the short term loading condition and 1.37 for the long term loading condition. Results of retaining wall global stability analysis are presented in appendix A. However, as mentioned earlier, our calculations indicate that the proposed retaining walls do not meet the recommended factor of safety for bearing for retaining walls ranging in height between 20 to 30 feet on the southeast side of the bridge (Close to B-5). At these locations we recommended extending the reinforcement straps to be equal to the full wall height instead of 0.7 times the wall height. 8.3 Embankments Slope Stability Results We have performed global slope stability analysis for the sloped embankment based on the proposed cross sections. We have assumed an embankment height of 25 feet close to borings B-1 and B-2. Our calculations indicate that the embankments with slope of 3(H):1(V) meet the recommended factors of safety for short term and long term stability. The factor of safety for the embankment slope stability was calculated as 1.80 for the short term loading condition and 1.59 for the long term loading condition. Results of slope stability analysis are also presented in appendix A. 9 EMBANKMENT SETTLEMENT ANALYSIS 9.1 General Settlement analyses were performed for the proposed embankments that will be constructed for the project. Based on information provided to us by Freese & Nichols, Inc. we understand that the proposed maximum embankment heights considered is approximately 25 feet on the west side and 30 feet on the east side of the bridge. We also understand that the length of the embankment is 8

16 approximately 1,350 feet on the west side and 500 feet on the east side of the bridge, and the width of the embankment is approximately 80 feet on both sides of the bridge. Embankment settlement will include settlement of the fill material for the construction of embankment and settlement of existing soils beneath the embankment. The following sections discuss the fill and foundation settlement that will have impact on the final constructed facilities. 9.2 Fill Settlement In general, we believe that settlement of the fill material placed above the natural soils will be substantially complete within a few months of completion of filling assuming that good quality fill material is used and that proper construction procedures are employed. Where water is allowed to flow through the embankment fill erosion of the fill may occur, this can lead to settlement of the anchorage and pavement. Also, where poor compaction of the fill is performed unusually large settlements may occur, and that settlement may continue for a long time. We believe that fill settlement will be substantially complete within a few months for granular fill and for low plasticity clay fill. For high plasticity clay fill settlement may occur within the fill for longer periods. We expect that clay fill with a liquid limit higher than about 45 placed with moisture content higher than about one percent above optimum moisture may continue to settle for as long as several years after filling is complete. For high plasticity fill placed several percent wet of optimum moisture content the total settlement that may occur after six months from the end of filling may be up to 0.5% of the fill height. If high plasticity fill is placed several percent dry of optimum the amount of settlement that may occur after six months will be negligible; however, high plasticity fill placed in this condition may swell causing pavement heave. Our experience shows that clay fill placed in the area often achieves acceptable density at moisture contents one percent above optimum, and in the winter months such fill is often accepted since drying the fill is practically impossible at that time of the year. In the summer months clay fill often achieves acceptable densities at moisture contents lower than 3% below optimum moisture content, and this fill is often accepted since wetting the clay is time consuming in the summer months. Both conditions can cause fill movement and may result in unacceptable levels of differential movement. For the purposes of the settlement analysis we have assumed that fill settlement will be complete within a few months of filling. If clay fill with a liquid limit higher than 45 is used in the embankment very careful moisture control during compaction will be needed to satisfy this assumption. We recommend that the General Note describing the Fill material include a requirement that the moisture condition of fill with a liquid limit greater than 45 be controlled during compaction such that it is within the range of 2% below to 1% above optimum moisture content. 9.3 Foundation Settlement Existing soils will undergo immediate elastic settlements and long-term consolidation settlements. Elastic settlement of the on-site soils should occur within a few months after embankment construction, and should have little impact on the final constructed facilities. As part of the study, we performed consolidation settlement analyses of the embankment foundation soils based on our laboratory tests and soil conditions encountered in the soil borings. Foundation soils are defined as the natural soils located beneath the embankment or retaining wall. Consolidation settlements of the natural soil beneath the embankment and retaining wall were estimated at the corner and along the edge of the retaining wall for the full embankment height to investigate retaining wall differential settlement. The following table summarizes our calculations estimated settlement: 9

17 Location Settlement at Edge of Retaining Wall (Center of Abutment) (in) Settlement at Corner of Retaining Wall (Center of Abutment) (in) Differential Settlement of Retaining Wall at Abutment (in) Embankment on West Side of Bridge Embankment on East Side of Bridge Abutment-Interior Bent Differential Settlement As discussed earlier, it is possible that the consolidation settlement of soils at the abutment due to the embankment fill may cause settlement of the abutment foundation. The amount of abutment foundation settlement that will occur depends on the elevation of the shaft base. For shafts extending to limestone, little settlement due to that layer will impact the abutment foundations. If the interior bent is far enough away from the embankment, its settlement will not be impacted by the consolidation settlement due to placement of the embankment. If the abutment foundations extend into limestone then the differential settlement between the abutment and interior bent is expected to be less than ½ inch. In considering the foundation depth for design the following should be considered: The differential settlement between the abutment and the embankment fill, The differential settlement between the interior bent and the abutment, and The schedule for construction of the abutment foundations relative to the embankment construction. To the extent deepening the abutment foundations reduces the differential settlement between the interior bent and abutment; it will increase the differential settlement between the abutment and the embankment fill. Please see Section 9.5 for further discussion of the differential settlement between the embankment fill and abutment. 9.5 Bridge Abutment to Embankment Differential Settlement Differential movement along the pavement extending from the bridge abutment out onto the fill adjacent to the abutment should be considered during design. Any differential settlement between the embankment and bridge abutment that occurs after paving will be concentrated near the bridge abutment since the bridge is supported on deep foundations that will settle less than the embankment after paving occurs. Since our calculations indicate a maximum foundation soil settlement of 2.2 inches, we recommend placing the pavement several months after completion of the embankments. We understand that the construction schedule allows for a period of 6 months between the completion of the embankment and the placement of the pavement. We estimate the 10

18 remaining foundation soil settlement after 6 months to be less than 1 inch. In any case, we recommend that an approach slab be included in the design that is capable of gradually transitioning the anticipated settlement so that ride quality is not adversely affected. 10 PAVEMENT DESIGN RECOMMENDATIONS 10.1 General We understand that the project will also involve pavement design, and three alternative street classifications are being considered: 1.) Collector with 100,000 annual ESAL, 1.5% growth rate, and 25 years design life 2.) Four-lane Collector with 200,000 annual ESAL, 2.0% growth rate, and 30 years design life 3.) Arterial with 300,000 annual ESAL, 3.0% growth rate, and 30 years design life 10.2 Rigid Pavement Section The recommendations presented in this report for the pavement design were developed in accordance with the "AASHTO Guide for Design of Pavement Structures", 1993 Edition. The design procedure for determining concrete slab thickness for rigid pavement is based on an extension of the algorithms that were originally developed from the AASHTO Road Test. The categories required for the design of pavement includes: (a) design variables, (b) performance criteria, (c) pavement structural characteristics, (d) material properties for structural design, and (e) reinforcement variables. Parameters relative to these categories are discussed below. Reliability Level and Overall Standard Deviation. A reliability level (R) of 95 percent was selected for the pavement design performance. A mean value of the overall standard deviation (So) was selected to be 0.35 for rigid pavement. Serviceability. The serviceability of a pavement is defined as its ability to serve the type of traffic that uses the facility. The condition of the pavement after the performance period is characterized by a Terminal Serviceability Index (P t ), which is a function of the pavement structure. We recommend that a Terminal Serviceability Index of 2.5 be used for all pavements. Since the time at which a given pavement structure reaches its terminal serviceability depends on traffic volume and the original or initial serviceability (P o ), some consideration also must be given to the selection of P o. As obtained at the AASHTO Road Test, a P o value of 4.5 was selected. Drainage. The treatment for the expected level of drainage for a rigid pavement is through the use of a drainage coefficient, C d. A C d value of 1.2 was selected for good quality of drainage. We have assumed that good quality drainage will be used on this project. Load Transfer. The load transfer coefficient, J, is a factor used in rigid pavement design to account for the ability of a concrete pavement structure to transfer load across discontinuities, such as joints. Based on the values developed by AASHTO, a mean value of the load transfer coefficient (J) of 3.2 was selected for the design of jointed reinforced concrete pavement with tied curbs. Loss of Support. This factor, LS, was included in the design of rigid pavement to account for the potential loss of support arising from subbase erosion and/or differential vertical soil movement. An LS value of 1.0 was selected according to the AASHTO suggestion for the condition of stabilized soils beneath the pavement. 11

19 Effective Modulus of Subgrade Reaction. Based on the subgrade soils encountered, we have estimated a subgrade resilient modulus of 1,800 psi. Based on the loss of support factor (LS) described previously (LS=1.0), an effective modulus of subgrade reaction (k) was found to be 61 pci. Concrete Elastic Modulus and Modulus of Rupture. A mean value of 600 psi for S'c was selected for the design. A value of 3.12 x 10 6 psi was used for the modulus of elasticity of the concrete (Ec) using the correlation recommended by the American Concrete Institute. Where, Ec = 57,000(f c) 0.5 Ec = elastic modulus of concrete in psi and, f c = compressive strength of concrete in psi; a value of 3000 psi is used here Rigid Pavement Thickness Based on the above parameters, we calculated the minimum concrete pavement thickness for the three different street classification alternatives. The following table summarizes our findings: Street Classification Collector with 100,000 annual ESAL, 1.5% growth rate, and 25 years design life Four-lane Collector with 200,000 annual ESAL, 2.0% growth rate, and 30 years design life Arterial with 300,000 annual ESAL, 3.0% growth rate, and 30 years design life Minimum Recommended Concrete Pavement Thickness (in) In addition, we recommend that six inches of the subgrade soils be stabilized with 6% lime by dry weight if the subgrade soil is cohesive type (fat clays, sandy clays, lean clays, sandy lean clays ), or 2% lime and 8% fly ash by dry weight if the subgrade soil is cohesionless type (sands, clayey sands ). The 6% lime will be equivalent to 40 pounds per square yard. The 2% lime and the 8% fly ash will be equivalent to 10 and 40 pounds per square yard, respectively. The above amounts for stabilization are provided for estimation purposes. The exact amount of lime and fly ash should be determined by testing the exposed subgrade during construction Preparation of Subgrade The subgrade soils along the pavement alignment generally consist of both cohesive and cohesionless soils. We recommend that at least six inches of the subgrade be stabilized. Stabilization of the subgrade should increase the modulus of subgrade reaction and provide subgrade stability for construction during inclement weather. In addition, subgrade stabilization should enhance long-term pavement performance by reducing the tendency of the soil to displace by pumping. We recommend the following procedures for subgrade preparation. 1. Clear the existing pavement section. 12

20 2. Strip the surface soil to suitable depths. In areas where soft, compressible or loose soils are encountered, additional stripping may be required. Stripping should extend a minimum of two feet beyond the edge of the proposed pavement where possible. 3. Surfaces exposed after stripping should be proof-rolled in accordance with TxDOT Standard Specification Item 216 or equivalent City of Fort Worth specification. If rutting develops, tire pressures should be reduced. The purpose of the proof-rolling operation is to identify any underlying zones or pockets of soft soils and to remove such weak materials. 4. Before stabilizing the subgrade, scarify the upper eight inches of exposed surface as required, mix with lime if subgrade soils are cohesive or lime and fly ash if subgrade soils are cohesionless, and compact it to 95 percent of standard proctor maximum dry density (ASTM D698). The amount of lime or lime and fly ash shall be determined for subgrade soils by conducting laboratory tests on the exposed subgrade material during construction. 11 SITE PREPARATION The site should be cleared, grubbed and stripped of all organic material, soft soils and foreign material within the proposed development area. Stripped areas should be appropriately graded and shaped to prevent ponding of water. Pumping may occur if the site becomes wet. All subgrade soils should be proof rolled in accordance with TxDOT Standard Specifications prior to placement of fill or paving. Fill material that is used should be placed and compacted in accordance with TxDOT Standard Specifications. 12 DESIGN REVIEW HVJ Associates, Inc. should review the design and construction plans and specifications prior to release to make certain that the geotechnical recommendations and design criteria presented herein have been properly interpreted. 13 LIMITATIONS This investigation was performed for the exclusive use of Freese and Nichols, Inc. for the proposed Clearfork Main Street Bridge crossing USACE channel in Fort Worth, Texas. HVJ Associates, Inc. has endeavored to comply with generally accepted geotechnical engineering practice common in the local area. HVJ Associates, Inc. makes no warranty, express or implied. The analyses and recommendations contained in this report are based on data obtained from subsurface exploration, laboratory testing, the project information provided to us and our experience with similar soils and site conditions. The methods used indicate subsurface conditions only at the specific locations where samples were obtained, only at the time they were obtained, and only to the depths penetrated. Samples cannot be relied on to accurately reflect the strata variations that usually exist between sampling locations. Should any subsurface conditions other than those described in our boring logs be encountered, HVJ Associates, Inc. should be immediately notified so that further investigation and supplemental recommendations can be provided. 13

21 PLATES

22 SITE N DATE: 08/20/ King S. Dairy Arthur Ashford Dr. Road Houston, Dallas, TX Texas Ph Fax Fax APPROVED BY: PREPARED BY: FF DK SITE VICINITY PLAN Stonegate Boulevard Bridge PROJECT NO.: DG DRAWING NO.: PLATE 1

23 SITE N DATE: 08/20/ S. Dairy Ashford Road 9200 King Arthur Dr. Dallas, Houston, TX Texas Ph Fax Fax APPROVED BY: PREPARED BY: FF DK GEOLOGY MAP Stongate Boulevard Bridge PROJECT NO.: DRAWING NO.: DG PLATE 2

24 R-1 B-1 B-2 B-3 B-4 B-5 R-2 N DATE: 08/20/ King S. Dairy Arthur Ashford Dr. Road Houston, Dallas, TX Texas Ph Fax Fax APPROVED BY: PREPARED BY: FF DK PLAN OF BORINGS Stonegate Boulevard Bridge PROJECT NO.: DG DRAWING NO.: PLATE 3

25 Project: Stonegate Boulevard Bridge Boring No.: B-1 Groundwater during drilling: --- Groundwater after drilling: --- LOG OF BORING Date: 6/18/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 0 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA SOIL/ROCK CLASSIFICATION Very stiff to hard, light brown and gray SANDY LEAN CLAY (CL) % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT w/ gravel 0'-4' w/ calcium nodules 4'-8' Light tan and gray LIMESTONE 56 LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ THD 50/0.5", 50/0.25" THD 50/0.0", 50/0.0" Shear Types: = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 4a

26 Project: Stonegate Boulevard Bridge Boring No.: B-1 Groundwater during drilling: --- Groundwater after drilling: --- LOG OF BORING Date: 6/18/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 35 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA THD 50/1.0", 50/0.25" SOIL/ROCK CLASSIFICATION Light tan and gray LIMESTONE % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT THD 50/0.5", 50/0.25" 45 THD 50/1.0", 50/0.25" 50 THD 50/0.75", 50/0.25" 55 THD 50/0.75", 50/0.25" LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ THD 50/0.75", 50/0.25" Shear Types: = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 4b

27 Project: Stonegate Boulevard Bridge Boring No.: B-2 Groundwater during drilling: --- Groundwater after drilling: --- LOG OF BORING Date: 6/24/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 0 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA SOIL/ROCK CLASSIFICATION Very stiff, light brown SANDY LEAN CLAY (CL) calcium nodules % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT Tan CLAYEY SAND (SC) w/ gravel THD 30/6.0", 30/6.0" Tan WEATHERED LIMESTONE LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ THD 50/0.5", 50/0.0" THD 50/0.5", 50/0.0" Gray LIMESTONE Shear Types: = Hand Penet. = Torvane 52 = Unconf. Comp. = UU Triaxial PLATE 5a

28 Project: Stonegate Boulevard Bridge Boring No.: B-2 Groundwater during drilling: --- Groundwater after drilling: --- LOG OF BORING Date: 6/24/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 35 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA THD 50/0.5", 50/0.0" SOIL/ROCK CLASSIFICATION Gray LIMESTONE % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE PLASTIC LIMIT CONTENT, % LIQUID LIMIT THD 50/1.0", 50/0.0" 45 THD 50/1.0", 50/0.25" 50 THD 50/0.5", 50/0.0" 55 THD 50/0.75", 50/0.0" LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ Shear Types: THD 50/1.0", 50/0.0" = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 5b

29 Project: Stonegate Boulevard Bridge Boring No.: B-3 Groundwater during drilling: 22 feet Groundwater after drilling: --- LOG OF BORING Date: 6/22/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 0 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA SOIL/ROCK CLASSIFICATION Firm to very stiff, light brown SANDY LEAN CLAY (CL) % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT Light gray LIMESTONE w/ mix of sand and clay (mud) LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ THD 50/0.0", 50/0.0" THD 50/0.5", 50/0.0" Shear Types: = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 6a

30 Project: Stonegate Boulevard Bridge Boring No.: B-3 Groundwater during drilling: 22 feet Groundwater after drilling: --- LOG OF BORING Date: 6/22/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 35 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA THD 50/0.5", 50/0.25" SOIL/ROCK CLASSIFICATION Light gray LIMESTONE w/ mix of sand and clay (mud) % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT THD 50/1.0", 50/0.25" Gray LIMESTONE 45 THD 50/1.0", 50/0.25" 50 THD 50/0.75", 50/0.0" 55 THD 50/0.75", 50/0.0" LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ THD 50/0.75", 50/0.25" Shear Types: = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 6b

31 Project: Stonegate Boulevard Bridge Boring No.: B-4 Groundwater during drilling: 8 feet Groundwater after drilling: --- LOG OF BORING Date: 6/24/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 0 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA SOIL/ROCK CLASSIFICATION Firm to very stiff, light brown and gray SANDY LEAN CLAY (CL) w/ limestone chunks and gravel % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT Midium dense to dense, tan and brown CLAYEY GRAVEL (GC) w/ sand 25 LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ Gray LIMESTONE w/ clay inclusions 50-50/1.0" Shear Types: = Hand Penet. = Torvane 40 = Unconf. Comp. = UU Triaxial PLATE 7a

32 Project: Stonegate Boulevard Bridge Boring No.: B-4 Groundwater during drilling: 8 feet Groundwater after drilling: --- LOG OF BORING Date: 6/24/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 35 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA THD 50/0.25", 50/0.0" SOIL/ROCK CLASSIFICATION Gray LIMESTONE w/ clay inclusions % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT THD 50/0.5", 50/0.0" 45 THD 50/0.5", 50/0.0" 50 THD 50/0.0", 50/0.0" 55 THD 50/0.0", 50/0.0" LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ THD 50/0.0", 50/0.0" Shear Types: = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 7b

33 Project: Stonegate Boulevard Bridge Boring No.: B-5 Groundwater during drilling: 21 feet Groundwater after drilling: --- LOG OF BORING Date: 6/20/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 0 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA SOIL/ROCK CLASSIFICATION Firm to stiff, light brown SANDY LEAN CLAY (CL) % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT Very loose to dense, tan and gray CLAYEY SAND (SC) w/ gravel and rock LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ sandy clay layers 33'-35' Shear Types: = Hand Penet. = Torvane 27 = Unconf. Comp. = UU Triaxial PLATE 8a

34 Project: Stonegate Boulevard Bridge Boring No.: B-5 Groundwater during drilling: 21 feet Groundwater after drilling: --- LOG OF BORING Date: 6/20/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 35 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA SOIL/ROCK CLASSIFICATION Very loose to dense, tan and gray CLAYEY SAND (SC) w/ gravel and rock % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT Gray LIMESTONE 45 THD 50/0.5", 50/0.0" 50 THD 50/0.5", 50/0.0" 55 THD 50/0.25", 50/0.0" LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ Shear Types: THD 50/0.0", 50/0.0" = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 8b

35 Project: Stonegate Boulevard Bridge Boring No.: R-1 Groundwater during drilling: --- Groundwater after drilling: --- LOG OF BORING Date: 6/17/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 0 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA SOIL/ROCK CLASSIFICATION Very stiff to hard, light brown, brown and light gray SANDY LEAN CLAY (CL) % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT w/ calcium nodules LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ Shear Types: = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 9

36 Project: Stonegate Boulevard Bridge Boring No.: R-2 Groundwater during drilling: 12 feet Groundwater after drilling: --- LOG OF BORING Date: 6/19/2008 Northing: -- Easting: -- Project No.: DG Elevation: Station: -- Offset: -- ELEV. DEPTH, FEET 0 SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA SOIL/ROCK CLASSIFICATION Firm to very stiff, brown and dark brown SANDY LEAN CLAY (CL) w/ gravel % PASSING NO. 200 SIEVE DRY DENSITY PCF SHEAR STRENGTH, TSF MOISTURE CONTENT, % PLASTIC LIMIT LIQUID LIMIT Very loose, tannish brown CLAYEY SAND (SC) w/ gravel LOG OF SOIL BORING DG STONGATE BRIDGE.GPJ HVJ.GDT 9/1/ Shear Types: = Hand Penet. = Torvane = Unconf. Comp. = UU Triaxial PLATE 10

37 SOIL SYMBOLS Soil Types Thin Walled Shelby Tube SAMPLER TYPES No Recovery Clay Silt Sand Gravel Split Barrel Auger Modifiers Liner Tube Jar Sample Clayey Silty Sandy Construction Materials Cemented WATER LEVEL SYMBOLS Groundwater level determined during drilling operations Asphaltic Concrete Stabilized Base Fill or Debris Portland Cement Concrete Groundwater level after drilling in open borehole or piezometer Classification SOIL GRAIN SIZE Particle Size Particle Size or Sieve No. (U.S. Standard) Clay Silt Sand Gravel Cobble Boulder < mm mm mm mm mm > 200 mm < mm mm - #200 sieve #200 sieve - #4 sieve #4 sieve - 3 in. 3 in. - 8 in. > 8 in. DENSITY OF COHESIONLESS SOILS Descriptive Term Very Loose Loose Medium Dense Dense Very Dense Penetration Resistance "N" * Blows/Foot > 50 CONSISTENCY OF COHESIVE SOILS Consistency Very Soft Soft Firm Stiff Very Stiff Hard Undrained Shear Strength (tsf) > 2.0 PENETRATION RESISTANCE 3/6 50/4" 0/18" Blows required to penetrate each of three consecutive 6-inch increments per ASTM D-1586 * If more than 50 blows are required, driving is discontinued and penetration at 50 blows is noted Sampler penetrated full depth under weight of drill rods and hammer * The N value is taken as the blows required to penetrate the final 12 inches TERMS DESCRIBING SOIL STRUCTURE Fracture planes appear polished or glossy, sometimes striated Breaks along definite planes of fracture with little resistance to fracturing Small pockets of different soils, such as small lenses of sand scattered through a mass of clay Inclusion less than 1/4 inch thick extending through the sample Inclusion 1/4 inch to 3 inches thick extending through the sample Inclusion greater than 3 inches thick extending through the sample Soil sample composed of alternating partings of different soil type Soil sample composed of alternating seams or layers of different soil type PROJECT NO.: DG Soil sample composed of pockets of different soil type and laminated or stratified structure is not evident Having appreciable quantities of calcium carbonate Having appreciable quantities of iron A small mass of irregular shape S. Dairy Ashford Road 9200 King King Arthur Arthur Dr. Dr. Dallas, Houston, Dallas, TX TX Texas Ph Fax Fax KEY TO TERMS AND SYMBOLS USED ON BORING LOGS DRAWING NO.: PLATE 11

38 ROCK TYPES SAMPLER TYPES Limestone Shale Sandstone Thin-Walled Tube Rock Core Weathered Limestone Weathered Shale Weathered Sandstone Standard Penetration Test Auger Sample Highly Weathered Limestone Dolomite Granite THD Cone Penetration Test Bag Sample SOLUTION AND VOID CONDITIONS Void Cavities Interstice; a general term for pore space or other openings in rock. Small solutional concavities. Friable Low Hardness Moderately Hard Very Hard HARDNESS Crumbles under hand pressure Can be carved with a knife Can be scratched easily with a knife Cannot be scratched with a knife Vuggy Vesicular Containing small cavities, usually lined with a mineral of different composition from that of the surrounding rock. Containing numerous small, unlined cavities, formed by expansion of gas bubbles or steam during solidification of the rock. Slightly WEATHERING GRADES OF ROCKMASS Moderately (1) Discoloration indicates weathering of rock material and discontinuity surfaces. Less than half of the rock material is decomposed or disintegrated to a soil. Porous Cavernous Containing pores, interstices, or other openings which may or may not interconnect. Containing cavities or caverns, sometimes quite large. Most frequent in limestones and dolomites. Highly Completely Residual Soil More than half of the rock material is decomposed or disintegrated to a soil. All rock material is decomposed and/or disintegrated into soil. The original mass structure is still largely intact. All rock material is converted to soil. The mass structure and material fabric are destroyed. SPACING JOINT DESCRIPTION INCLINATION SURFACES Very Close Close Medium Close Wide <2" 2"-12" 12"-3' >3' Horizontal Shallow Moderate Steep Vertical Slickensided Smooth Irregular Rough Polished, grooved Planar Undulating or granular Jagged or pitted REFERENCES: (1) British Standard (1981) Code of Practice for Site Investigation, BS (2) The Bridge Div., Tx. Highway Dept. Foundation Exploration & Design Manual, 2nd Division, revised June, Information on each boring log is a compilation of subsurface conditions and soil and rock classifications obtained from the field as well as from laboratory testing of samples. Strata have been interpreted by commonly accepted procedures. The stratum lines on the logs may be transitional and approximate in nature. Water level measurements refer only to those observed at the times and places indicated, and may vary with time, geologic condition or construction activity. PROJECT NO.: DG BEDDING THICKNESS Very Thick Thick Thin Very Thin Laminated Thinly Laminated King S. Arthur Dairy Dr. Ashford Road Dallas, Houston, TX Texas Ph Fax Fax (2) >4' 2'-4' 2"-2' 1/2"-2" 0.08"-1/2" <0.08" KEY TO TERMS AND SYMBOLS USED ON BORING LOGS DRAWING NO.: PLATE 12

39 APPENDIX A SLOPE STABILITY RESUTS

40

41

42 STABL for Windows Report Date = 12/18/2008 Time = 12:05:05 AM Input Data

43 Segment Number Profile Defining Segment Coordinates Left Extreme X Left Extreme Y Right Extreme X Right Extreme Y Soil Under Segment Segment # 1 (Top) Segment # 2 (Top) Segment # 3 (Top) Segment # Soil Number Wet Unit Weight Saturated Unit Weight Soil Properties Cohesive Intercept Phi (deg) Ru Pressure Head Soil # Soil # Water Table

44 RESULTS Factors of Safety of Ten Most Critical Surfaces Surface Number Factor of Safety Surface # Surface # Surface # Surface # Surface # Surface # Surface # Surface # Surface # Surface #

45

46 STABL for Windows Report Date = 12/18/2008 Time = 12:17:17 AM Input Data

47 Segment Number Left Extreme X Profile Defining Segment Coordinates Left Extreme Y Right Extreme X Right Extreme Y Soil Under Segment Segment # 1 (Top) Segment # 2 (Top) Segment # 3 (Top) Segment # Soil Number Wet Unit Weight Saturated Unit Weight Soil Properties Cohesive Intercept Phi (deg) Ru Pressure Head Soil # Soil # Water Table

48 RESULTS Factors of Safety of Ten Most Critical Surfaces Surface Number Factor of Safety Surface # Surface # Surface # Surface # Surface # Surface # Surface # Surface # Surface # Surface #

49