基岩断层错动而引起的上覆土体变形会对地表以及地下结构物造成破坏。上覆土体的胶结特性和隐伏断层的存在,使得断层错动的变形机制更为复杂。采用滤纸技术模拟隐伏断层,通过2组离心机试验研究胶结土体中正断层裂缝的扩展机制及伴随的孔压变化规律。对土体的变形分析和孔隙水压力的监测加深了对地裂缝的认识。研究发现,正断层错动引起胶结黏土的变形机制为受弯变形。隐伏断层使得土体受弯区变小、土体破坏程度加剧。胶结黏土受弯形成的地裂缝分为张拉裂缝和剪切裂缝,这些地裂缝的发展为超孔压的消散提供了优势路径。
It is well-recognized that normal fault dislocation may cause severe damages to buildings and underground structures during earthquake. Understanding of deformation mechanisms of overlying soil becomes even more challenging in cemented soils with pre-existing fracture. Two groups of centrifuge tests were conducted to investigate deformation mechanism and variation of pore pressure during normal fault propagation in cemented clay. A filter paper technique was adopted to simulate the effects of a pre-existing fracture. A bending deformation mechanism was identified in cemented clay with and without the pre-existing fracture. Although the area of bending zone was reduced,the extent of damage was increased by the presence of pre-existing fracture. Observed fault ruptures could be characterized as tension cracks and shearing cracks. These ruptures provide preferential paths for dissipation of excess pore pressures generated during normal fault propagation.