不同固结时间崩岗土体抗剪强度的差异

Differences in Shear Strength of Colluvial Soil at Various Consolidation Time

在不同的固结条件下崩岗崩壁土体抗剪强度因孔隙变化、水分运动等而发生变化,深入了解崩岗土壤固结过程对抗剪强度的影响对于解析崩壁土体稳定性具有重要意义。为了给崩岗崩塌侵蚀过程研究提供基础数据和理论参考,通过对典型崩岗各土层试样进行不同时间预压固结,采用四联直剪仪测试土壤的抗剪强度,分析了固结时间与崩岗土体抗剪强度、黏聚力、内摩擦角的关系。结果表明:(1)崩岗红土层土体抗剪强度在土壤含水率为20%时相对较大但随固结时间的延长呈减小趋势,在含水率为24%~32%时随固结时间的延长变化相对较小;崩岗砂土层土体抗剪强度随固结时间延长,在垂直压强为100~200 kPa时变化较大,在垂直压强为50、300 kPa时变化较小;在不同固结时间情况下,崩岗碎屑层土体抗剪强度变化均较小。(2)随着固结时间的延长,崩岗红土层土体黏聚力在含水率为24%~32%时呈增大趋势,崩岗砂土层土体黏聚力在一定范围波动变化,崩岗碎屑层土体黏聚力受固结时间的影响较小。(3)随着固结时间的延长,崩岗红土层土体内摩擦角呈减小趋势,崩岗砂土层和碎屑层内摩擦角变化较小。

The shear strength under different consolidation conditions of collapsed wall has been changed due to porosity change and moisture movement.It is necessary to understand the impact of the soil consolidation process on the shear strength of collapse,which is essential for analyzing the stability of the collapsed wall.In order to provide essential data and theoretical reference for the study on the process of colluvial erosion,by preloading consolidation of each soil layer of a typical collapse at different times,we analyzed the shear strength,cohesion and internal friction angle of collapse under different consolidation times by using four-alliance direct shear apparatus.The results show that a)when the soil moisture content is 20%,the shear strength of red soil layer is relatively larger,whereas it tends to decrease with the extension of consolidation time.When the water contents are from 24%to 32%,it changes relatively little with the extension of consolidation time.When the vertical pressure is from 100 to 200 kPa,the shear strength of the sandy layer is changed greatly with the extension of consolidation time and relatively little when the vertical pressure is 50 kPa and 300 kPa.The shear strength of the detritus layer is changed less under different consolidation times.b)When the soil moisture content is from 24%to 32%,the cohesion in the red soil layer gradually is increased with the extension of consolidation time.The cohesion in the sandy soil layer fluctuates within a certain range and the cohesion in the detritus layer is less influenced by consolidation time.c)The internal friction angle of the red soil layer decreases gradually with the extension of consolidation time,whereas the sandy layer and the detritus layer changes less at different consolidation times.