| dc.description.abstract | In 1999, the Chi-Chi earthquake hit the central part of Taiwan and caused numerous loss of lives and properties. The offset of Chelungpu fault during this event induced severe ground deformation up to 5 m, and building failure can be found everywhere of the affected area. In order to study more of the building reaction during fault offset, we have modelled the fault offset with a shallow foundation of given properties.
The fault is modelled using the program Particle Flow Code in Two Dimensions (PFC2D). We have simulated a numerical model based on the sandbox test from Chang (2013), in which the model condition is under 80g (corresponding to maximum vertical displacement of 5 cm of the hanging wall). This study discussed the reverse fault with dry sandy soil in the condition of free field and shallow foundation. We used the way of the stress path variations, the principle stress direction and the ratio of dh/H with shear failure at different depth of the soils to investigate the result from numerical modeling. Furthermore, three different parameters, which are foundation load, embedding depth and placement position were also discussed about the interaction between the development of the shear zone and the rotation angle of the foundation in the study.
The results of the simulation show that the stress path variation of the sandy soil layer with fault rupture zone was mainly affected by the horizontal force , and the primary trend was lateral compression. Also, the results of the major principal stress direction, the horizontal stress was also the main direction in the fault rupture zone. In the other side, the ratio of the dh/H with shear failure shows that when the foundation load increase, the confining stress of the soil layer below the foundation would also increase, which required more fault displacement to cause the damage.
In the cases where the foundation loading is doubled, the embedding foundation and the foundation position affection, the results showed that: the relationship between the rotation angle of the foundation and the position was : (at the hanging wall which near the transition zone ) S/B=0 > (at the transition zone) S/B=0.69 > (at the footwall which near the transition zone) S/B=1 > (at the hanging wall far from the transition zone ) S/B=-2.39 > (at the footwall far from the transition zone) S/B=3.33. The safest position of the foundation was on the footwall, and about 15 meters away from the fault outcrop. In other tests, the foundation rotation angle at the hanging wall was larger. | en_US |