岩性差异变化对断层带结构影响的物理模拟

Physical simulation of the influence of lithological differences on fault zone structure

采用分解和统计相结合的实验原则,逐步考察了影响断层带结构变化的地层因素。通过对砂、泥岩力学性质及含量进行变换,模拟砂、泥岩地层中可能形成的断层带结构。实验结果表明：泥岩泊松比、泥岩含量是影响断层带结构及其内部单元规模的2个重要因素。单一的砂岩泊松比并不直接影响断层带结构类型,其原因可能是因为实验中的砂岩主要表现为脆性变形的结果;但砂岩含量是影响断层带结构类型的重要因素。在泥岩含量一定的情况下,砂岩泊松比的变化影响断层带的宽度,且两者比值在1～1.33之间时断层带发育二元结构;砂岩泊松比低于0.28、泥岩泊松比低于0.34时,断层带形成疏松的一元型结构;当砂岩泊松比高于0.35、泥岩泊松比高于0.38时,断层带为紧闭的一元型滑动面。

The controlling stratigraphic elements for fault zone structure were studied. Possible fault zone structures in sand and mudstone formations were simulated in view of sand and mudstone mechanical properties and contents. The Poisson＇ s ratio and content of mudstone controlled fault zone structure and its internal unit size. The Poisson＇ s ratio of sand did not directly determine fault zone structure, which might be explained by the brittle deformation of sand in the experiment. On the contrary, sand content was a key element for fault zone structure. When mudstone content was fixed, the Poisson＇ s ratio of sand controlled the width of the fault zone. When the ratio of mud to sandstone Poisson＇ s ratio was 1-1.33, dualistic structure developed in the fault zone. When the Poisson＇ s ratios of sand and mudstones were less than 0.28 and 0.34, respectively, a unitary fault zone with loose structure formed. When the Poisson＇ s ratios of sand and mudstones were more than 0.35 and 0.38, respectively, a closed unitary sliding surface developed.