PROPOSED CONSTRUCTION OF RESIDNTIAL APARTMENT AT BAJANAI KOIL STREET,SELAIYUR

Transcription

1 PROPOSED CONSTRUCTION OF RESIDNTIAL APARTMENT AT BAJANAI KOIL STREET,SELAIYUR Report on Geotechnical Investigation Client: M/s. Alankar Construction, Chennai. MARS SYNERGY GEO TECH Pvt Ltd ISO 9001: 2008 Company # 30/25 Drowpathy Amman Koil 1 st Street Velachery, Chennai Ph : (044) , Tele Fax: Mail : info@msgeotech.com, projects@msgeotech.com, Web: Project No: MSGTPL/SI-2746/14-15 Aug-2014.

2 TABLE OF CONTENTS Proposed Construction of Residential Apartment at Selaiyur 1.0 INTRODUCTION DESCRIPTION OF STRUCTURE SOIL INVESTIGATION PROGRAMME FIELD SAMPLING LABORATORY TESTS SOIL PROFILE GROUND WATER TABLE DISCUSSION ON FOUNDATION RECOMMENDATIONS SAFE BEARING CAPACITY CALCULATIONS SITE PLAN MSGTPL/SI BORE-LOGS TEST RESULTS NATURAL MOISTURE CONTENT SPECIFIC GRAVITY GRAIN SIZE ANALYSIS.. 10 Geo-Technical Investigation Report Project No: MSGTPL/SI-2746/14-15 Aug-2014

3 Proposed Construction of Residential Apartment at Selaiyur REPORT ON SUB SOIL INVESTIGATION AND RECOMMENDATION FOR THE FOUNDATION OF THE PROPOSED CONSTRUCTION OF RESIDENTIAL APARTMENT AT SELAIYUR. 1.0 INTRODUCTION M/s. Alankar Construction, Chennai are planning to construct the residential apartment at No.27, Bajanai koil Street, Bharathi Nagar, Selaiyur, Chennai , Tamilnadu, India. M/s. Mars Synergy Geotech Pvt Ltd, Chennai has carried out this investigation and completed the field work on 15 th Aug 2014 according to the instructions from the owner of the project. The scope of work includes the following: Making one number of Standard Soil Investigation bore-hole Collecting soil samples at regular depth intervals Conducting SPTs at every 1.0m/1.50m depth intervals Conducting laboratory tests on samples collected Submitting report with laboratory test results and recommendation for foundations. 1.1 DESCRIPTION OF STRUCTURE The proposed structure is residential apartment (Stilt+2). The exact details of columns are not available at the time of preparation of this report. Assuming an approximate column spacing of 4 to 5 m c/c considering this the central column load works about 60 to 75 tons for proposed building. These loads are assumed for the purpose of foundation only and for the structural design, exact loads are to be estimated based on a suitable structural analysis. 1.2 SOIL INVESTIGATION The field investigation works were carried out using 1 set of Rotary mechanical drilling Rig. The following activities, carried out in chronological sequence, comprised the fieldwork for the project Mobilisation of rotary drill rig, water pump, testing tools and accessories. Collection of disturbed samples of non-cohesive soils. Sampling and logging of the boreholes. Packing, labeling and dispatching the samples to laboratory. Field investigation, tests and laboratory tests conducted as per IS-1892 and IS Geo-Technical Investigation Report 1 Project No: MSGTPL/SI-2746/14-15 Aug-2014

4 Proposed Construction of Residential Apartment at Selaiyur 1.3 FIELD SAMPLING One number of standard soil investigation borehole of 100mm diameter was made at the location shown in the figure, MSGTPL/SI-2746 enclosed. Investigations were conducted 5.0m from existing ground level where SPT is more than 50blows. SPTs were conducted at every 1.0m depth intervals and samples were collected for identification and testing. 1.4 LABORATORY TESTS The laboratory-testing scheme is so designed to obtain the design parameters for the foundations. The following parameters are evaluated: Type of soil and it's gradation properties Specific Gravity Natural Moisture Content (NMC) Sieve analysis on the coarse grained soil fraction All the test results are presented in the tabular forms. Comprehensive field information along with SPT values is presented on separate sheet. 1.5 SOIL PROFILE: Based on visual identification of soil samples and test results (of both field and laboratory tests), the soil profile arrived. Subsoil is made-up of four distinctive layers there are (i) Medium dense SAND up to -1.0m with SPT s N=12 (ii) Very dense moorum -1.0m to -2.0m with SPT s N=>50 (iii) Soft disintegrated Rock -2.0m to -4.0m with SPT s N=>100 (iv) Fractured Hard Rock -4.0m to -5.0 with core recovery is 5% The soil profile details are presented in the bore-chart. 1.6 GROUND WATER TABLE At the time of soil investigation (15/08/2014), the ground water table was (-)3.20m encountered within the drilled depth Geo-Technical Investigation Report 2 Project No: MSGTPL/SI-2746/14-15 Aug-2014

5 Proposed Construction of Residential Apartment at Selaiyur 1.7 DISCUSSION ON FOUNDATION From the sub soil profile and laboratory test data, it can be seen that the soil is medium dense sand up to -1.0m followed by very dense moorum up to -2.0m followed by soft disintegrated rock up to -4.0m below this layer 1.0m thick fractured hard rock up to -5.0m from exciting G.L Based on soil strata open shallow foundation can be adopted at -2.0m level from existing ground level. 1.8 RECOMMENDATIONS Excavate up to -2.0m, after excavation proper compaction to be done. Open shallow foundation in the form of isolated/strip raft located at a depth of 2.0m below the G.L The Safe bearing capacity can be taken of soil at 2.0m below G.L can be taken as 25T/sq.m. These footing should rest on 100mm thick of 1:3:6 mat. Columns shall be tied in both directions at plinth level. All foundation works should be done in dry conditions only. Note: This recommendation has been given on the assumed loads. The structural engineer can modify based on structural analysis on actual size of the building and column details. Geo-Technical Investigation Report 3 Project No: MSGTPL/SI-2746/14-15 Aug-2014

6 Proposed Construction of Residential Apartment at Selaiyur 2.0 DETERMINATION OF BEARING CAPACITY OF SHALLOW FOUNDATIONS [Based On IS: ] Type of Foundation: Isolated footing Width of footing: 2mx2m (For Calculation Purpose) Depth of Foundation: 2.0m Existing Ground level: 0.00M Ground Water Table level: -0.00M (Due to Heavy Rain Temporary) Bulk Density (W) of Soil above Footing Base: 1.80 Submerged Density (W') of Soil above Footing Base: 0.80T/Cu.M. Bulk Density (W) of Soil below Footing Base: 1.80T/Cu.M. Factor of Safety 3.0 Shape factor Depth Factor Inclination Factor Sq = Dq = 1.18 Iq = Sg = Dg = 1.18 Ig = Water Table Correction Factor w = 0.50 Effective surcharge at base level q = 1.60T/Sq.M. Ultimate Net B.C. = Qult_n = q*(nq-1)*sq*dq*iq + 0.5*B*W*Ng*Sg*Dg*Ig*W' Angle of Internal Friction (phai): 33 0 Bearing Capacity Factors Nq = 27.34, Ng =37.78 Thus Qult_n =83.75 T/Sq.M. Allowable Bearing Capacity (Qall) = 83.75/3.0= T/Sq.M. Say 25 T/m 2 Settlement Calculations as per IS-8009-(Part1) 1998 S= Sc+Si Sc 5mm Si = 2 (1 µ ) pb I Es 2 (1 0.3 ) Si = 25x = m 2500 S= Sc+Si =0.0172x1000=17.29mm S= =22.29mm Say 23mm Total settlements 23mm, It is less than 25mm hence safe as per IS Geo-Technical Investigation Report 4 Project No: MSGTPL/SI-2746/14-15 Aug-2014

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8 4.0 BORE-LOGS Project : Proposed Construction of Residential Apartment at Selaiyur Bore Hole No. :BH-1 Type of Boring :Rotary Started on : 15/08/2014 Ended on : 15/08/2014 G.W.T :(-)3.20m Dia of Boring :100mm Location : Ref. Fig Total Depth : 5.0m R.L of Layers Soil Profiles Soil Description Brownish Coarse Sand IS Classification SM Depth (m) 0.0 SPT Details N 0 Graphical Representation of SPT Type of Samples SPT Brownish Moorum SM Blows for 9Cm SPT Soft Disintegrated Rock GP Blows for 0Cm SPT >100 SPT 5.00 Fractured Hard Rock Very Poor Borehole Terminated at 5.0m Below Ground Level. 5.0 Core Recovery-5% Rock Soil Profile at BH-1 Location 6

9 5.0 TEST RESULTS Project : Proposed Construction of Residential Apartment at Selaiyur BH No 1 Ground Water Level:(-)3.20m NMC WL WP IP Ic FreeSwell Gravel Coarse Sand Medium Sand Fine Sand Silt & Clay Cohesion, C (kg/sq.cm.) Angle of friction SUMMARY OF TEST RESULTS Index Properties (%) Grain Size Analysis (%) N' Value Specific Gravity Termination Depth: -:5.0m Direct Shear Depth (m) Depth (m) Soil Description Soil Classification UCC Strength (kn/sq.m) Brownish SAND Brownish Moorum > > Soft Disintegrated Rock > Very Poor GP SM SM Rock Fractured Hard Rock 7

10 6.0 NATURAL MOISTURE CONTENT Project : Proposed Construction of Residential Apartment at Selaiyur Date:20/08/2014 Method: IS-2720 P-2 BH.No/ Pit no Depth (m) Tare No Wt of Tare (gr) Tare + Soil (gr) Tare+Dry soil (gr) Wt of Water (gr) Wt Dry soil (gr) Water Content (%) Average Water Content (%) Natural Moisture Content Data Sheet 2.0 8

11 7.0 SPECIFIC GRAVITY Project : Proposed Construction of Residential Apartment at Selaiyur SPECIFIC GRAVITY TEST BH.No 1 BH.No 1 Depth(m) 1.0 Depth(m) 2.0 Pycnometer number Pycnometer number 19 8 Weight of bottle w 1 g Weight of bottle w 1 g Weight of bottle + soil w 2 g Weight of bottle + soil w 2 g Weight of bottle + soil + water w 3 g Weight of bottle + soil + water w 3 g Weight of bottle full of water w 4 g Weight of bottle full of water w 4 g Weight of soil w 2 -w 1 g Weight of soil w 2 -w 1 g Specific gravity w2-w1 (w4-w1)-(w3-w2) Specific gravity w2-w1 (w4-w1)-(w3-w2) Average value G s 2.61 Average value G s

12 8.0 GRAIN SIZE ANALYSIS Project : Proposed Construction of Residential Apartment at Selaiyur BH 1 Sieve Analysis Test Depth 1.0m S.No Sieve Aperture size used (mm) passing Average Particle Diameter = % Soil Cumulative % retained Finer Average Sieve PSR % F % size (mm) (1) (2) (3) Product of Columns (1) x (3) BH 1 Depth 2.0m S.No. Sieve Aperture size used (mm) passing Average Particle Diameter = % Soil Cumulative % retained Finer Average Sieve size (mm) (2) (3) PSR % (1) F % Product of (1) x (3) Clay Silt Sand Gravel Fine Medium Coarse Fine Medium Coarse Fine Cumulative Percentage Finer Particle size [mm] I Depth II Depth Depth = 1.0 % Particle Size Depth = 2.0 % Gravel 3 D 10 = Gravel 36 Coarse Sand 46 D 30 = Coarse Sand 13 D Medium Sand = Medium Sand 10 Fine Sand 11 C u = Fine Sand 19 Silt & Clay 24 C c = Silt & Clay 22 Particle Size D 10 = D 30 = D 60 = C u = C c = 10