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Geotechnical analysis

Vacuum consolidation FE, coupled analysis of temporary works, SSI seismic analysis, 3D-MODFLOW

Overview

Numerical analysis and stability review as design and construction evidence

Vacuum consolidation analysis

FE with PVD and vacuum — consolidation, displacement, and stress

Review purpose	Evaluate consolidation progress under staged vacuum loading, drain spacing, and concurrent embankment conditions Predict displacement and stress to assess effects on adjacent ground and structures
Key findings	Confirm inward horizontal displacement and accumulated consolidation settlement under vacuum loading Confirm residual settlement and the overconsolidated state after vacuum removal Review strength increase resulting from increased effective stress

FE modeling — layers, PVD, constraints — Modeling

Deformation contours — Deformation

Settlement vs duration — Settlement

Temporary works stability

Stress–pore-pressure coupled analysis for excavation stability

Review purpose	Develop a rational structural design based on design criteria, site-condition surveys, and geotechnical investigation results Evaluate stability through coupled stress–pore-water-pressure analysis considering groundwater flow
Key findings	Identify horizontal ground displacement and the ground stress state Check wall stresses, strut and temporary-anchor axial forces, and compliance with allowable displacement criteria

Elastoplastic model with English soil legend — Elastoplastic modeling

FEM mesh — FEM modeling

Elastoplastic result

FEM result

SSI seismic analysis

SSI with dynamic soil parameters and stiffness matrix

Review purpose	Evaluate a stiffness matrix based on dynamic soil parameters Improve seismic-analysis reliability by comparing results with conventional analyses, including fixed-head foundation assumptions
Review sections	Foundation section — review displacement distribution, including equal-displacement contours Temporary works section — review equal-displacement contours and displacement time histories
Key findings	Check whether maximum horizontal displacement satisfies the allowable criterion

SSI mesh and nodes — Modeling

Effective vertical stress (Hachinohe)

Horizontal displacement

Excess pore-water pressure

3D-MODFLOW groundwater impact

Aquifer, water-level, and flow impact from excavation

Review purpose	Predict groundwater changes in adjacent aquifers caused by excavation such as underpasses After steady-state simulation and calibration, predict water-level changes and flow rates over the construction period
Modeling and influence range	3D-MODFLOW modeling Groundwater-level influence range during construction for non-cutoff and cutoff conditions Steady-state groundwater-surface distribution
Key findings	Predict expected groundwater drawdown for cutoff and non-cutoff excavation → review the need for a cutoff method Review groundwater inflow caused by excavation

Grid — inactive area — Grid

Geology — bedrock and fill — Geologic conditions

Water table — Water-table distribution

Groundwater inflow