Shear Band Development of Overburden Soil Induced by Growth Normal Fault Slip
Date Issued
2014
Date
2014
Author(s)
Chu, Sheng-Shin
Abstract
A fault slip can cause the deformation of shallow soil layers and destroy infrastructures. The Shanchiao Fault on the west side of the Taipei Basin is one such fault. The activities of the Shanchiao Fault have caused the quaternary sediment beneath the Taipei Basin to become deformed, damaging structures, traffic construction, and utility lines in the area.
Data on geological drilling and dating have been used to determine that a growth fault exists in the Shanchiao Fault. In an experiment, a sandbox model was built using noncohesive sandy soil to simulate the existence of a growth fault in the Shanchiao Fault and forecast the effect of the growth fault on shear-band development and ground differential deformation. The experimental results indicated that when a normal fault contains a growth fault at the offset of the base rock, the shear band develops upward beside the weak side of the shear band of the original-topped soil layer, and surfaces considerably faster than that of the single-topped layer. The offset ratio required is approximately one-third that of the single-cover soil layer. In this study, a numerical simulation of the sandbox experiment was conducted using a discrete element method program, PFC2D, to simulate the upper-covering sand layer shear-band development pace and the scope of a growth normal fault slip. The simulation results indicated an outcome similar to that of the sandbox experiment.
According to the above test results, the Wuku profile geometric simulation model established in this study, the new hanging wall thickness H is 5/16 of the original thickness in every sedimentary strata of the growth normal fault. The simulation results show that the more average offset will lead the shear-band propagation reached close to the ground surface.
The PCF2D program was used to create a model for simulating SCF-2 and WK-1E profiles and the shear-band propagation reached the particle surface in the final 2.5-m slip of this growth normal fault numerical model. The simulation results can be applied to the design of construction projects near fault zones.
Subjects
生長正斷層
分離元素法PFC2D
山腳斷層
臺北盆地
Type
thesis
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