Let s Make a Difference. Presented by: Samuel Tran, P.E.

Transcription

1 Let s Make a Difference Presented by: Samuel Tran, P.E. October 22, 2015

2 OVERVIEW o Importance of Geotechnical Engineering o Geotechnical Foundation Recommendations o Geotechnical Construction Specifications Let s Make a Difference

3 GEOTECHNICAL ENGINEERING o Surface and Subsurface Construction o Tunneling, Structural Foundation, Earthwork o Soil Mechanics o Plasticity Index, Moisture, Consolidation, Swell Potential o Ground Improvement o Lime / Cement Stabilization o Vibro Compaction o Band Drains

4 GEOTECHNICAL ENGINEERING o Slope Stabilization o Albert Atterberg, Henry Darcy, Joseph Boussinesq, William Rankine, Karl Terzaghi o Atterberg Limits Test, Permeability, Stress Distribution, Earth Pressure, Bearing Capacity for foundations

5 FOUNDATION RECOMMENDATIONS o Shallow Foundation o Spread Footing o Slab-On-Grade o Mat Foundation

6 FOOTING CONSTRUCTION During design the foundation plan and the utility plan should be cross checked to verify that no utility line excavation (existing and/or proposed) extends beneath the bearing influence of any footing.

7 FOOTING CONSTRUCTION Measurements Verify proper dimensions of the footings (height, width, depth, etc.) Verify proper rebar sizes and placements Verify proper reinforcing overlaps Verify proper clearance and that chairs are used Verify vapor barrier placement

8 FOOTING CONSTRUCTION Prior to Concrete Placement Verify that the base is free of loose soil and debris Verify that there is no ponding water Verify that the subgrade has not softened due to being saturated by rain

9 FOUNDATION RECOMMENDATIONS o Deep Foundation o Straight Shaft Piers o Structural Floor over crawl space or void space o Pier Foundation with slab-on-grade o Piles o Micropiles, Sheet Piles, Soldier Piles o Timber, Steel, Composite Piles Prestressed Concrete Piles,

10 FOUNDATION RECOMMENDATIONS Straight Shaft Piers Founded in Rock Skin Friction End Bearing Bell Piers (Under-reamed) Founded in Clay End Bearing

11 PIER DRILLING INSPECTION Engineering staff reviews the approved structural drawings and geotechnical report Verify Foundation Type, Penetration, Bearing Stratum Identify the pier types and locations Pre-meeting with the Geotechnical Engineer, Driller, & Engineering Technician

12 PIER DRILLING INSPECTION

13 PIER DRILLING INSPECTION Engineering Technician Verify Technician has updated structural plans Verify Diameter and Penetration Drilling Contractor Required to have a straddle bar, plumb bob and pier tape Follow direction of the engineering technician

14 PIER DRILLING INSPECTION

15 PIER DRILLING INSPECTION

16 PIER DRILLING INSPECTION Excessive water seepage or cave in will require steel casing The casing diameter and length needs to be recorded Each Steel Casing should be properly identified

17 PIER DRILLING INSPECTION

18 PIER DRILLING INSPECTION Extremely important to maintain a sufficient head of concrete during casing extraction.

19 PIER DRILLING INSPECTION Bell Piers (Under-reamed) A straight shaft is drilled to the respective depth determined by the engineer. The depth of the pier is measured before and after the belling process. Verify there are no soil build-up at the bottom of the pier.

20 PIER DRILLING INSPECTION Bell Piers (Under-reamed) will require a bell checker

21 FOUNDATION ISSUES Sulfate induced heaves Expansive Clay Austin Chalk, Eagle Ford Shale, Woodbine Moisture Conditioning, Water Injection, Chemical Injection

22 CONSTRUCTION SPECIFICATIONS Excavation Limits beyond building limits/sidewalks Bait and Switch on Select Fill PI verification per 5,000 sq/lift

23 CONSTRUCTION SPECIFICATIONS Excavation Limits beyond building limits/sidewalks Make sure correct proctors are being used. Percent Compaction per ASTM D698 or Modified Proctor D1557

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25 Typical Moisture and % Compaction Comparison Versus Hand Penetrometer Readings Pocket Pen High PI Clay Sandy Clay (PI=25) Readings (tsf) Mc % Compaction Mc % Compaction % +5 90% % +3 95% 3.0 opt % opt % % % % %

26 o Refer to a Geotechnical Engineer for foundation issues o Plan Ahead Make sure everyone is on the same page during the construction phase o Have qualified and certified inspectors o There are no dumb questions

27 THANK YOU