干湿循环下考虑裂隙发育的残积土边坡响应分析

Response analysis of residual soil slope considering crack development under drying-wetting cycles

为研究带裂隙的花岗岩残积土边坡在反复干湿循环作用下的响应规律,利用模型试验模拟干湿循环过程,通过处理裂隙图像量化裂隙宽度扩展,结合坡内土体直剪试验,推导强度衰减规律和裂隙深度相关的计算公式。对比模型试验和数值模拟结果,分析考虑裂隙发育下的残积土边坡响应情况,结果如下:干湿循环下残积土裂隙宽度扩展符合Logistic模型,裂隙深度与强度衰减有确定的量化关系,且随着干湿循环次数增加,裂隙深度趋于稳定;干湿循环次数较少时,坡底位置含水率变化明显滞后于坡顶和坡中位置,但随着干湿循环次数增加及裂隙扩展,边坡各位置的含水率变化趋于一致。裂隙扩展对边坡各位置变形均有影响,随着干湿循环次数增加,考虑裂隙扩展的坡底和坡中位置变形与不考虑裂隙的情况趋于一致,但坡顶区域变形更大,致使裂隙边坡的坡顶与坡底的变形差距增加。

In order to study the response of granite residual soil slope with cracks under different number of drying-wetting cycles(D-W cycles),model test was carried out and the crack width expansion index was quantified by investigating the crack images.Based on the direct shear test,the calculation formulas of soil strength degradation and crack depth were developed.Then,the model test and the numerical simulation results were compared to analyze the response of the residual soil slope considering crack extension.The results showed that the fractures width expansion in residual soil under D-W cycles followed the Logistic model,and there was a quantitative relationship between fracture depth and strength degradation.The fracture depth tended to be stable with the increase of D-W cycles.When the number of D-W cycles was small,the change of moisture content at the bottom of the slope lags significantly behind that at the top and the middle of the slope,however,the change of moisture content at each position of the slope tended to be the same with the increase of D-W cycles.The deformation at the bottom and the middle of the slope with the crack expansion tended to be the same compared to the slope without cracks,however,the deformation at the top area was larger,which led to the increase of the deformation gap between the top and bottom of the cracked slope.