不同胶结度断层泥强度参数与含水率关系

Relationship between strength parameter and water content of fault gouge with different degrees of consolidation

断层泥的强度参数对断层的强度有重要影响,而断层泥的强度参数与其胶结度和含水率密切相关。通过对不同胶结度和含水率断层泥试样开展直剪试验,获得了断层泥的主要强度参数——黏聚力c和内摩擦角?,并对其与含水率和胶结度的关系进行了分析研究,取得了如下结论:(1)不同胶结度断层泥试样的内摩擦角均随含水率的升高而降低,但降低程度较小;(2)不同胶结度断层泥试样黏聚力随含水率升高而变化的过程可划分为3个阶段,即上升期、急剧下降期、缓慢下降期,这3个阶段由第一拐点和第二拐点分隔开;(3)随着胶结度的增大,断层泥试样的内摩擦角逐渐升高,但变化不大,且内摩擦角随含水率升高而降低的程度有逐渐减小的趋势;(4)随着胶结度的增大,断层泥试样黏聚力第一拐点位置的含水率迅速增大,而第二拐点位置含水率的变化相对较小;(5)断层泥胶结度与第一拐点含水率的关系可用二次多项式函数进行描述。

The strength of fault is significently influenced by the strength parameters of fault gouge, which are closely related to the consolidation degree and water content. In this study, specimens of fault gouge with different consolidation degrees and water contents are subjected to the direct shear test to obtaincohesion c and internal friction angle φ, which are the dominant strength parameters of fault gouge. Based on the results of test, the relationships between the two strength parameters and consolidation degree and water content of fault gouge are analyzed and following conclusions can be drew. The internal friction angles of fault gouge specimens with different consolidation degrees decrease as the water contents increase, but the decrease of internal friction angle is slight. The trend between cohesion of fault gouge specimens of different consolidation degrees and the water content can be divided into three stages: ascent stage, steep descent stage and slow descent stage. These three stages are separated by the first inflection point and the second inflection point. As the consolidation degree increases, the internal friction angle of fault gouge increases gradually but slightly. Meanwhile, the descresing rate of the internal friction angle of fault gouge tends to descrese with the increase of the water content. As the consolidation degree increases, the water content of fault gouge whose cohesion is at the first inflection point increases rapidly, while the water content of fault gouge whose cohesion is at the second inflection point changes slightly.The relationship between consolidation degree of fault gouge and the water content of fault gouge whose cohesion is at the first inflection point can be described by a quadratic polynomial function.