Foundations and Earthwork Stott Bushnell, Cathryn Cecil, Tyler Cecil, and Craig Fowler – BFCC...
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Foundations and Earthwork Stott Bushnell, Cathryn Cecil, Tyler Cecil, and Craig Fowler – BFCC Engineering Residential foundations are very stiff, often tied together with grade beams. They usually remain intact after liquefaction, despite large settlements (>3 in). The structures are almost always repairable Design-Build of the Block 25A Academic Building The purpose of this project is to provide geotechnical evaluations and recommendations for AMEC Foster Wheeler for use in the design build of the Block 25A Academic Building for the University of California, San Francisco, Mission Bay Campus. The building will be a six story office building with a partial seventh story with a footprint of 44,000 square feet, located on the corner of 16th Street and 4th Street in San Francisco. BFCC Engineering characterized the site based on geology, existing soil, and seismic hazards and gives recommendations for retaining wall and foundation design. Project Description Acknowledgments Thanks to our sponsor, Alex Wright and AMEC Foster Wheeler, for their support and guidance. Thanks as well to Dr. Kevin Franke and Levi Ekstrom for their advice University of California, San Francisco, Mission Bay Campus BFCC The site lies in an area that has high potential for ground shaking and liquefaction due to large faults and clayey soils in the area. A design response spectrum was created to show the typical maximum accelerations for a building on the site, so that engineers could design the seismic aspects of the building accordingly. To better access the liquefaction potential, an analysis of the soil and nearby faults were done. Using liquefaction software and nearby fault data, a liquefaction hazard report was made based off the 475 and 2475 return-year earthquake. It was found that the site has high potential for liquefaction. To mitigate these hazards, it is recommended to do soil improvements, and design the foundation to resist the effects of liquefaction. Seismic Hazards A description of the subsurface soils was created using field exploration and laboratory testing of samples. There were about 3 boring logs and corresponding analyses completed and the raw data was given to us. There were also about 8 cone penetration tests completed in various locations on the site. This data was used to complete a soil profile to make it easier to see what type of soil is present and other properties of the soil. The groundwater levels for the site is an important property gained. Soil Description Depth (ft) Description Plasticity PI LL WaterContent(%) DryUnitWeight(pcf) 1 AsphaltConcrete (4in.), Aggregate Base (3in.) 2 10 119 3 4 106 4 5 6 7 8 9 9 131 10 11 12 Groundw ater 13 14 15 16 17 18 HP 19 20 21 22 34 68 57 67 23 24 25 HP 26 27 56 67 28 29 30 31 48 74 32 33 34 HP 53 97 74 56 35 36 37 38 39 40 41 42 73 56 43 44 45 46 HP 39 73 60 64 47 48 49 50 51 52 53 54 55 56 MP 57 58 59 60 61 62 63 64 65 66 ClayeySand PoorlyGraded Sand ClayeySand ClayeyGravel w ith Sand ElasticSiltto FatClay SiltySand SandyLean Clay Serpentine and Shale (Bedrock) Depth (ft) Blow countsperft Sam ple # ASTM Sym bol Description Plasticity PI LL WaterContent% DryUnitW eight(pcf) 2.5 50 1 SC ClayeySand 10 119 5 18 2 SP PoorlyGraded Sand 4 106 6.5 100 3 SP PoorlyGraded Sand 10 24 4 SC ClayeySand 9 131 15 14 5 GC ClayeyGravel w ith Sand 21.5 1 6 CH ElasticSiltto FatClay 34 68 57 67 26.5 1 7 CH ElasticSiltto FatClay 56 67 31.5 1 8 CH ElasticSiltto FatClay 48 74 35 50 psi 9 CH ElasticSiltto FatClay HP 53 97 74 56 36.5 1 10 CH ElasticSiltto FatClay 41 1 11 CH ElasticSiltto FatClay 46.5 1 12 CH ElasticSiltto FatClay HP 39 73 60 64 51.5 65 13 SC SiltySand 56.5 16 14 CL SandyLean Clay 60.5 120 15 Serpentinite and shale 65.5 140 16 Figure 3: Site Layout with Boring Hole Locations Figure 5: Site Location In Liquefaction Hazard Zone Map Figure 6: Liquefaction Hazard Report Figure 7: Site Design Response Spectrum igure 1: Soil Profile of Northeast Section of Site Figure 2: Boring Log Data for Northeast Section of Site Figure 4: AutoCAD Details of Recommended Foundation Pile and Retaining Wall
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Transcript of Foundations and Earthwork Stott Bushnell, Cathryn Cecil, Tyler Cecil, and Craig Fowler – BFCC...
Foundations and Earthwork
Stott Bushnell, Cathryn Cecil, Tyler Cecil, and Craig Fowler – BFCC Engineering
Residential foundations are very stiff, often tied together with grade beams. They usually remain intact after liquefaction, despite large settlements (>3 in). The
structures are almost always repairable
Design-Build of the Block 25A Academic Building
The purpose of this project is to provide geotechnical evaluations and recommendations for AMEC Foster Wheeler for use in the design build of the Block 25A Academic Building for the University of California, San Francisco, Mission Bay Campus. The building will be a six story office building with a partial seventh story with a footprint of 44,000 square feet, located on the corner of 16th Street and 4th Street in San Francisco. BFCC Engineering characterized the site based on geology, existing soil, and seismic hazards and gives recommendations for retaining wall and foundation design.
Project Description
AcknowledgmentsThanks to our sponsor, Alex Wright and AMEC Foster Wheeler, for their support and guidance. Thanks as well to Dr. Kevin Franke and Levi Ekstrom for their advice and support.
University of California, San Francisco, Mission Bay Campus BFCC
The site lies in an area that has high potential for ground shaking and liquefaction due to large faults and clayey soils in the area. A design response spectrum was created to show the typical maximum accelerations for a building on the site, so that engineers could design the seismic aspects of the building accordingly. To better access the liquefaction potential, an analysis of the soil and nearby faults were done. Using liquefaction software and nearby fault data, a liquefaction hazard report was made based off the 475 and 2475 return-year earthquake. It was found that the site has high potential for liquefaction. To mitigate these hazards, it is recommended to do soil improvements, and design the foundation to resist the effects of liquefaction.
Seismic Hazards
A description of the subsurface soils was created using field exploration and laboratory testing of samples. There were about 3 boring logs and corresponding analyses completed and the raw data was given to us. There were also about 8 cone penetration tests completed in various locations on the site. This data was used to complete a soil profile to make it easier to see what type of soil is present and other properties of the soil. The groundwater levels for the site is an important property gained.
Soil Description
Depth (ft) Description Plasticity PI LL Water Content (%) Dry Unit Weight (pcf)1 Asphalt Concrete (4 in.), Aggregate Base (3 in.)2 10 1193 4 106456789 9 131
101112 Groundwater131415161718 HP19202122 34 68 57 67232425 HP2627 56 6728293031 48 74323334 HP 53 97 74 563536373839404142 73 5643444546 HP 39 73 60 6447484950515253545556 MP57585960616263646566
Clayey Sand
Poorly Graded Sand
Clayey Sand
Clayey Gravel with Sand
Elastic Silt to Fat Clay
Silty Sand
Sandy Lean Clay
Serpentine and Shale (Bedrock)
Depth (ft) Blow counts per ft Sample # ASTM Symbol Description Plasticity PI LL Water Content % Dry Unit Weight (pcf)
2.5 50 1 SC Clayey Sand 10 119
5 18 2 SP Poorly Graded Sand 4 106
6.5 100 3 SP Poorly Graded Sand
10 24 4 SC Clayey Sand 9 131
15 14 5 GC Clayey Gravel with Sand
21.5 1 6 CH Elastic Silt to Fat Clay 34 68 57 67
26.5 1 7 CH Elastic Silt to Fat Clay 56 67
31.5 1 8 CH Elastic Silt to Fat Clay 48 74
35 50 psi 9 CH Elastic Silt to Fat Clay HP 53 97 74 56
36.5 1 10 CH Elastic Silt to Fat Clay
41 1 11 CH Elastic Silt to Fat Clay
46.5 1 12 CH Elastic Silt to Fat Clay HP 39 73 60 64
51.5 65 13 SC Silty Sand
56.5 16 14 CL Sandy Lean Clay
60.5 120 15 Serpentinite and shale
65.5 140 16
Figure 3: Site Layout with Boring Hole Locations
Figure 5: Site Location In Liquefaction Hazard Zone Map
Figure 6: Liquefaction Hazard Report
Figure 7: Site Design Response Spectrum
Figure 1: Soil Profile of Northeast Section of Site
Figure 2: Boring Log Data for Northeast Section of Site
Figure 4: AutoCAD Details of Recommended Foundation Pile and Retaining Wall
