干湿循环下红黏土裂隙发育及抗剪强度劣化规律研究

The Study of Crack Development and Shear Strength Deterioration of Red Clay Soil Under Dry and Wet Cycles

干湿循环条件下红黏土裂隙发育及抗剪强度劣化问题受到广泛关注,采用室内试验方法,对不同压实度、含水率和干湿循环次数影响下红黏土裂隙发育以及干湿循环对抗剪强度的劣化规律开展研究。结果表明:相同压实度红黏土,含水率对裂隙发育有较大影响,含水率较低试件产生网格状裂隙,而含水率较高试件主要产生长而宽的带状裂隙;裂隙率和裂隙长度比随循环次数增加而提高,且含水率越高,红黏土越松散,裂隙率和裂隙长度比也越大,裂隙发育程度越高;不同含水率下红黏土粘聚力和内摩擦角均随循环次数增加先快速衰减后逐渐趋于稳定,且当含水率相同时,压实度越高,衰减速度越快。此外,含水率变化对4次干湿循环后粘聚力和内摩擦角衰减量影响可以忽略不计,从而得到不同压实度下的粘聚力与内摩擦角平均衰减率,并发现干湿循环对粘聚力影响大于内摩擦角的影响。

The problem of the crack development and the shear strength deterioration of the red clay soil under the dry and wet cycles has gained widely attention.The crack development and the shear strength deterioration of the red clay soil with the change of the degree of compaction,water content and times of dry and wet cycles has been studied by the laboratory test in this paper.The results show that the moisture content of the red clay soil with the same degree of compaction has significant effect on the crack development.The grid cracks develop in the red clay soil with the low water content,while the long and wide strip cracks develop in the red clay soil with high water content.It is also found that the crack ratio and the crack length ratio raise with the times of dry and wet cycles.the higher the water content and the low density of the red clay,the greater the crack ratio and the crack length ratio and the higher the crack development degrees.The cohesion and the internal friction angel of the red clay soil with different water content decrease rapidly at the first and then gradually stabilize.The higher the degree of compaction of the red clay soil with same water content,the faster the decay ratio of the cohesion and the internal friction angel of the red clay soil.Moreover,the results also show that the decrement of the cohesion and the internal friction angel of the red clay soil with 4 times of the dry and wet cycles can be ignored and the average decay ratio of the cohesion and the internal friction angel with the different degree of compaction can obtained which indicate that dry and wet cycles has more significant effect on the cohesion than the internal friction angel.