Laboratory simulation of shear band development in a growth normal fault
Journal
Journal of GeoEngineering
Journal Volume
8
Journal Issue
1
Pages
19-26
Date Issued
2013
Author(s)
Abstract
Studies on active faults in the metropolitan Taipei area have indicated that the Shanchiao fault at the western rim of the Taipei Basin is a highly active normal fault. Fault slip can cause the deformation of shallow soil layers and lead to the destruction of residential building foundations, utility lines, and other infrastructure near the influenced area. The Shanchiao fault is considered a growth normal fault based on geological drilling and dating information. Therefore, a geological structure similar to a growth normal fault was constructed to simulate slip-induced ground deformation after an additional layer of sedimentation formed above the deformed normal fault. We employed a sand box with non-cohesive sands under normal gravity conditions to investigate the shear band propagation and surface deformation of a growth normal fault. In the presence of a sandy sedimentation layer on top of the deformed sandy soil layer caused by a normal fault, a shear band developed along the previous shear band and propagated upward to the sandy surface at a much faster speed compared to the case without a sedimentation layer (i.e., normal fault only). An offset ratio of 1%~ 1.5% (defined as the fault tip offset displacement over the soil layer thickness) for this particular growth fault simulation is required to develop a shear band toward the ground surface. The test results indicated that the shear band of a growth normal fault with sandy material could propagate to the ground surface only under a smaller offset displacement from the fault tip, although the depositional thickness of the upper layer might be very thick. Therefore, a seismic design integrated with the knowledge of near-ground deformation characteristics for this type of fault must be emphasized in current building codes, particularly for critical facilities such as a nuclear power plant.
Type
journal article