正断层与逆断层错动引起的上覆黏土变形特性离心试验

Centrifuge test of deformation characteristics of overburden clay subjected to normal and reverse fault rupture

采用土工离心机试验,研究正断层和逆断层错动引起上覆饱和黏土层在20步连续断层错动作用下的变形特性以及裂缝扩展的规律。研究结果显示,正断层错动后地表呈现多条且平行断层面的张拉裂缝,随着错动量的增大,正断层破裂逐渐偏离基岩断层的错动方向,偏向上盘一侧,裂缝逐渐向上盘的方向开裂,裂缝主要发生在断层延长线附近;逆断层错动后地表裂缝均分布在上盘,而且离断层尖端延长线较远,产生的裂缝较细、数量较少,随着断层错动量的增大,地表位移增大,靠近断层下盘一侧的地表受断层错动影响较小,位于断层上盘一侧的地表则随着断层错动显著移动;随着断层错动量的增大,最大地表坡度随之增大,正断层引起的最大坡度的位置逐渐向上盘方向移动,逆断层引起的最大坡度的位置逐渐向下盘方向移动,逆断层的影响范围比正断层的影响范围更广。

centrifugal tests with 20-step normal and reverse faulting were conducted to investigate the deformation characteristics and rupture propagation of overburden saturated clay. The results show that, duo to normal fault, several paralleled tensile ruptures appear on surface. Normal fault rupture gradually shifts from dip slip direction toward to the hanging wall as the throw increases. Ruptures develop toward to the hanging wall and mainly appear near fault rupture line. Whereas as a result of reverse faulting, smaller and less ruptures appear in hanging wall, relatively far from fault rupture line. The displacement increases as the throw increases. Ground below fault rupture line remains stationary during faulting; but above fault rupture line it moves compatibly with the hanging wall. The peak slope increases as the throw increases. The peak slope position shifts toward to the hanging wall for normal faulting and to footwall for reverse faulting. The reverse faulting induced impact region is larger than that by normal faulting.