地层错动引起的上覆饱和黏土层变形特性的离心试验研究

地震断层错动会引起上覆土层变形，从而造成断层附近的建筑结构、管线产生附加的变形和内力引起破坏。通过一个土工离心机试验分析上覆饱和黏土层在4步连续断层错动作用下的静力响应行为。着重分析断层错动引起的地层变形的范围、不均匀沉降区的分布特点、剪切裂缝在土层传播路径及地表开裂的位置等工程上重点关注的问题。得到以下几点认识：(1) 基岩断层错动引起的地层变形范围基本上不受基岩错动量大小的影响。(2) 断层错动引起地层的不均匀沉降区基本呈三角形分布，其地表宽度约为1倍左右的土层厚度。(3) 基岩错动引起的主剪切裂缝基本沿竖直方向向上传播，其传播距离取决于基岩错动量及土体的破坏应变。(4) 基岩断层错动在主剪区的下盘一侧边缘会产生张拉裂缝，且产生张拉裂缝所需基岩错动量远小于产生剪切裂缝所需的错动量。

Centrifuge modelling of ground deformaitons induced by normal fault in saturated clay

Ground deformations induced by normal fault can cause severe damages to infrastructures and pipe line systems nearby.In this paper,the results of a centrifuge test simulating multiple-step normal faulting in saturated clay are reported.The test focuses on the area and characteristic of distortion zone,fault propagation and location of surface ruptures.Based on the test,it is found that(1) the magnitude of normal fault movement has insignificant effect on the area of the distortion zone at the ground surface;(2) the shape of distortion zone in the clay is triangular and the width of this distortion zone at the ground surface is about the same as the depth of the soil underneath;(3) the main fault rupture propagates upward vertically;and(4) surface ruptures are located at the edge of the distortion zone on the side of the bedrock foot wall.Normal fault displacement required for the development of tension cracks at the ground surface is smaller than that required for fault rupture to outcrop the ground surface.