基于含水率改变的抗剪强度指标折减方法在膨胀土基坑支护设计计算中的应用

Shear Strength Index Reduction Method Based on Water Content Change in Design and Calculation of Foundation Supporting in Expansive Soil

通过膨胀土室内试验,得到了膨胀土含水率与抗剪强度指标的定量关系。试验研究表明,抗剪强度指标随含水率的增加呈逐渐降低的趋势,与内摩擦角φ相比,黏聚力c对含水率的变化更加敏感,含水率每增加5%,黏聚力c降低7.5kPa,内摩擦角φ降低3°。在此基础上,提出了适用于膨胀土基坑支护设计计算的基于含水率改变的抗剪强度指标折减方法,并通过工程实例计算与现场监测验证了该方法在膨胀土基坑支护设计中的适用性。

Based on the laboratory test of expansive soil,the quantitative relationship between water content and shear strength index was statistically analyzed.Research shows that the shear strength index gradually decreases with the increase of water content.Compared with the internal friction angleφ,the cohesive force c is more sensitive to changes in water content.For each 5%increase in water content,cohesion c decreases by 7.5 kPa and internal friction angleφ3°lower.On this basis,a shear strength index reduction method based on changes in water content was proposed for the design and calculation of expansive soil foundation pit support.The applicability of this method in the design of expansive soil foundation pit support was verified through engineering case calculations and on-site monitoring.