Deformation in sandy soil during normal faulting

Abstract
When normal fault slips, especially triggered by earthquakes, the deposit alluvium may deform and a fault zone also develops within itself. The deformation in alluvium might bright terrible damage to overground and underground structures. So, to find the deformation range of overburden soil and locate the fault rupture is an essential issue to evaluation the safety of ground or underground structures near the potential faulted zone. On the basis of previous research by Cole and Lade (1984), this research further explores the processes of noraml faulting within the sandy soil, studying the influences of corresponding factors or parameters and the range of influential zones using physical model tests and numerical analysis for both small-scale and full-scale. Moreover, this study collected field case near Sanchiao fault in Taipei basin, useing numerical analysis to find out the damage zone.
The experimental results indicate different fault dip angle influence the range of damage zone. In the low dip angle test, failure surface develop both side of upthrow and downthrow. The range of failure zone is larger than the high dip angle test. The result of the low dip angle test, it develop the structure of graben which only occurred in normal faulting.
In small-scale analysis, the numerical simulation tends to have similar result as those of sandbox experiments, include the range of influence zone and location of the surface rupture. Among stress paths exploration, the damage zone is reach failure criteria, it could understand where the worst zone is. In the study, the tension zone occurs primarily in the highly disturbed upthrown block. In full-scale analysis, it is a useful numeral analysis to judge the structure in the damage zone or not.
The numerical analysis program is a helpful tool to quantity the deformation of soil during normal faulting. In the future, more analysis of filed case can understand the influence zone of Taipei basin near Sanchiao fault. It can supply designers to improve the safety of the structure, and far from the damage zone.