Evaluation of the seismic performance of geotechnical structure
The definition of soil liquefaction and how it works?
Soil liquefaction is a phenomenon in which the strength and stiffness of a saturated soil/sand is reduced by earthquake sharing or other rapid loading. The pressures generated during large earthquake shaking can cause the liquefied sand and excess water to force its way to the ground surface. Thus the structures such as bridge or large buildings constructed on pile foundations may lose the support from the adjacent soil and come to rest at a tilt after shaking.
A Simple Constitutive Model for Soil Liquefaction Analysis
UBSSAND model is developed to simulate the liquefaction phenomenon using plastic theory based on explicit method for 2D effective stress state. It is extended to enable implicit the nonlinear analysis for 3D stree state based on the constitutive model.
The pore water pressure in stress analysis can be divided into normal state pore water pressure and abnormal state pore water pressure - the excess pore water pressure generated between soil particles due to external loading under undrained conditions. An excess pore water pressure of nearly 0 is called the drainage condition.
This is the most general case where the input stiffness parameters and strength parameters are the parameters of the ground skeleton. Like drained analysis, GTS NX uses the input stiffness/strength parameters for undrained analysis. The disadvantage is that the effective strength parameters in the undrained state are hard to obtain through experimentation.
Dynamic approach of numerical modeling in GTS NX
- Constitutive models capable of capturing liquefaction