Interaction between Co-seismic Ground Deformation and the Shallow Foundation Induced by Oblique-Slip Faulting

• Main Authors: Chun-Yuan Liu, 柳鈞元
• Other Authors: Ming-Lang Lin
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/xx5ws4

碩士 === 國立臺灣大學 === 土木工程學研究所 === 107 === Central Geology Survey（MOEA）so far have announced 33 active faults. 9 of them have scientific evidences for characteristic of oblique-slip faulting. In addition to strong ground motion, co-seismic ground deformation, induced by basement offset, pose a great risk to artificial structure. Infrastructure along surface rupture would be severely damaged. However, the stiffness of foundation is large than overburdened soil layer, which restricted the propagation of underground fault slip plane and surface rupture develop along foundation’s corner. With different rake angle, foundation are force to dislocation, inclination and horizontal rotation to different degrees in oblique-slip faulting. In this research, we placed emphasis on the oblique-slip faulting. By simplified the fault plane to be 60 degrees and assumed the overburden soil to be no cohesive sediment, downscaled sandbox tests were conducted and a rectangle metal block are serve as a embedded shallow foundation. With the help of photogrammetry, high-resolution digital surface data are obtained. In the free field, Riedel shear, induced by strike-slip offset, and fault scarp, induced by dip-slip offset combined to form a complicated rupture lineation. Shallow foundation incline and rotate more than 10 degrees when the basement oblique slip reach 0.3H （thickness of overburden soil）. The dislocation of foundation force the surrounding overburden soil to form passive deformation. In the view of adaptation, the foundation would have less damage if the long axis direction of shallow foundation opposite to the strike-slip direction. As for mitigation, the foundation should avoid from triangular shear zone as much as possible. In 1999 chichi earthquake, chelungpu fault oblique slip in the fengyuan-shihgang area. The fault rupture line cross through a building complex, 3 buildings located within the fault zone severely inclined and rotated due to 3.5 m uplift and 3.5 m left-lateral offset. Base on previous field surveys, aerial photo and cadastral map, we reconstruct the structure type and size. We use distinct element model （PFC3D） to simulate the damage process of the building complex. The result of simulation are close to the field survey after the chichi earthquake. The position of foundation, long axis direction and oblique-slip characteristic have much effect in the interaction between shallow foundation and oblique-slip faulting.