Key Projects
Soil-Structure Interaction, North Shore Pumping Station Project, San Francisco, California
M2C evaluated the seismic stability of sections of the Northshore Pumping Station seismic design and retrofit project located in San Francisco, California. We provided a one-dimensional site response analysis using Fast Lagrangian Analysis of Continua (FLAC) to plot the free field spectral response and compare to the Target Spectra. Seven time histories were used in the 1D SHAKE and 1D FLAC site response analyses and comprised the following:
● Preparation of a 2D and 3D SSI FLAC model to model soil and structure interaction behavior during simulated shaking.
● Model Tunnel and pipelines into and surrounding the pumping station and study impact of tunnel and pipelines from surrounding pile and building foundations. Implement the 3-d liquefaction simulations and potential for buoyancy and design implications from the 3D SSI models. Comment on use of pile wall thickness and implementation of flexible couplings and strengthened deep foundations for pipelines and tunnels in models.
● Capture the 2D and 3D SSI model response at the free field as well as at the top of the structural wall and compare and calibrate the FLAC free field to the SHAKE, 1D FLAC results and target spectra used for structural design. The top of wall spectral response from 2D FLAC and any structural amplification relative to the target spectrum and free field will be evaluated and provided to the design team.
● Record acceleration, horizontal stresses and horizontal displacement histories along the perimeter of the irregular shape structure walls and document model performance. Estimate and provide racking displacements imposed on the structure both during simulated shaking as well as permanent deformation at the end of shaking resulting.
● Prepare a report summarizing the results of the findings. Additionally, provide electronic files (in MS Excel format) including the results of the study.
Soil-Structure Interaction, Milpitas Station BART SVBX Project, California
M2C evaluated the seismic stability of sections of the Milpitas Station BART SVBX Project, in Milpitas, California and provided a one-dimensional site response analysis using Fast Lagrangian Analysis of Continua (FLAC) to plot the free field spectral response and compare to the Target Spectra. Three pre-approved time histories were used in the 1D FLAC site response analyses and comprised the following:
● Preparation of a 2D FLAC model to model soil and structure interaction behavior during simulated shaking.
● Capture the 2D FLAC model response at the free field as well as at the top of the structural wall and compare and calibrate the FLAC free field to the SHAKE, 1D FLAC results and target spectra used for structural design. The top of wall spectral response from 2D FLAC and any structural amplification relative to the target spectrum and free field will be evaluated and provided to the design team.
● Record acceleration, horizontal stresses and horizontal displacement histories along the box structure walls and document model performance. Estimate and provide racking displacements imposed on the box structure both during simulated shaking as well as permanent deformation at the end of shaking resulting.
● Prepare a report summarizing the results of the findings. Additionally, provide electronic files (in MS Excel format) including the results of the study.
TN_1_SSI Analysis Summary_and_Figures_v1.pdfMilpitas_SBVX_Report_Figures_App_REV_10-16-13-v2.pdf
Geotechnical Investigation 30% Conceptual Design Phase OCSD Wastewater Storage and Reclamation Project, Site 3A & 3C-2, Occidental, California
The project comprised a feasibility study and two design-level geotechnical investigations for two potential 12.5 million gallon capacity wastewater reservoir sites, referred to as Site 3A and Site 3C-2, located just outside the town of Occidental in West Sonoma County, California.
The report's purpose was to (1) identify geological and geotechnical constraints and advantages to development and (2) establish criteria for the design and Construction of proposed earthen construction storage reservoirs at the sites. Work performed included a detailed background literature review, geological field mapping, subsurface geotechnical explorations (test pits, soil and rock borings, CPTs and a seismic refraction survey), laboratory analysis and stability evaluations. Detailed investigation initially focused on Site 3A, however, Site 3A was judged inadequate for cost-effective Construction due to factors including high groundwater, weak expansive soils, liquefaction potential, inadequate slope and earthquake stability and asbestiform materials in serpentinite bedrock and overlying soils within the excavation footprint. As a result, the investigation was broadened, which led to the detailed investigation of Site 3C-2.
The results of the investigation for Site 3C-2 indicated favorable conditions for Construction and long-term usage. Site 3C-2 is underlain by rippable, highly weathered, weak sandstone conglomerate from the existing ground surface to 24 feet to 41 feet. This is underlain by more competent but still weak, weathered and variable graywacke sandstone and shale sedimentary sequences. Both units may be used for embankment fill construction. Excess material may be exported for use as fill on other sites. Stability analyses of the approximately 45 foot deep excavation below existing grade necessary to establish the reservoir show that the interior and exterior slopes will be stable in Construction, in long term static loading and during rapid drawdown conditions (sudden drainage of the reservoir). Seismic analysis based on the maximum credible earthquake (MCE) of magnitude 7.9 from the San Andreas Fault (which is approximately 12.16 km (7.6 miles) away and is the controlling design seismic source for the site) indicate an adequate factor of safety. No known active faults cross the site, so fault rupture is not anticipated. Serpentinite bedrock containing asbestiform minerals is located immediately to the southwest of the proposed 3C-2 reservoir footprint and extends to the depths explored. No evidence of the occurrence of serpentinite was observed in the excavation area. If the area of serpentinite remains undisturbed, it does not affect the construction feasibility of the 3C-2 reservoir.
Seismic Stability analysis of Pier G, Port of Long Beach, CA: (Client: Kleinfelder Inc.)
I evaluated the seismic stability of sections of the Milpitas Station BART SVBX Project, in Milpitas, California and provided a one-dimensional site response analysis using FLAC to plot the free field spectral response and compare to the Target Spectra. Three pre-approved time histories were used in the 1D FLAC site response analyses and comprised the following:
Prepared a 2D FLAC model to model soil and structure interaction behavior during simulated shaking.
Capture the 2D FLAC model response at the free field as well as at the top of the structural wall and compare the calibrate the FLAC free field to the SHAKE, 1D FLAC results and target spectra used for structural design. The top of wall spectral response from 2D FLAC and any structural amplification relative to the target spectrum and free field will be evaluated and provided to the design team.
Record acceleration, horizontal stresses and horizontal displacement histories along the box structure walls and document model performance. Estimate and provide racking displacements imposed on the box structure both during simulated shaking as well as permanent deformation at the end of shaking resulting.
Prepare a report summarizing the results of the findings. Additionally, provide electronic files (in MS Excel format) including the results of the study.
Kaiser Hospital, San Leandro, CA: (Client: Ferrell Design Build Inc. / URS Corporation)
I performed both 2D and 3D-FLAC modeling services for URS Corporation to study the dynamic soil structure interaction for Rammed Aggregate Piers and surrounding soil. The reviewing agency OSHPD required the model to show the kinematic interaction between the pile and soil and provide estimates for maximum shear strains generated during an earthquake for the proposed hospital site. I performed initial runs using SHAKE2000 and used 3 horizontal spectra matched time-histories to perform the dynamic model. The site response and dynamic analysis were reviewed by URS engineers. I performed these complex services within a 4 week period.