含水量与抗剪强度关系影响下高盐量盐渍土路基边坡稳定性

Stability of high salinity saline soil subgrade slope under influence of water content and shear strength

针对盐渍土中不同盐分类型的溶解度和亲水性差异较大问题,分析高盐量盐渍土含水量与抗剪强度关系变化对盐渍土路基边坡稳定性的影响。结合降雨量调查和现场含水量沿深度分布情况,开展适应环境条件的室内试验。针对不同含水量条件下高氯盐渍土(CL-1)和高硫低氯盐渍土(CL-2)路基填料进行直剪试验,得出含水量与抗剪强度参数关系函数。基于Geostudio建立盐渍土路基含水量-强度参数等值分层计算模型,通过体积压力板仪试验测量土样基质吸力随体积含水量的变化规律。通过采用饱和/非饱和渗流的有限元分析与路基边坡稳定性的极限平衡分析相结合的方法,利用GeoStudio中SLOPE/W模块,分别计算和分析降雨强度、降雨持续时间等对盐渍土路基边坡稳定性的影响。考虑含水量和抗剪强度变化关系函数,通过建立的盐渍土路基含水量-强度参数等值分层计算模型对CL-1和CL-2盐渍土边坡稳定性进行了分析。结果表明:含水量在最优含水量的基础上增加3%时,CL-1和CL-2的黏聚力较最优含水量时分别下降94.3%和54.0%,内摩擦角的变化不大;在最优含水量的基础上减少3%时,CL-1和CL-2的黏聚力较最优含水量时分别提高了277.1%和89.7%,对CL-2的内摩擦角影响不大,CL-1的内摩擦角出现明显减小;当降雨强度相同时,CL-1填筑的路基的安全系数较CL-2填筑的路基变化更为明显,主要原因在于高氯盐的亲水性较硫酸盐强,抗剪强度参数受到水分变化的影响更大。

Amid at the solubility and hydrophilicity of different salinity types in saline soils were quite different, the influence of the relationships between the water content and shear strength of saline soils on the stability of saline soil roadbed slopes were analyzed, combined with the rainfall survey and the depth distribution of the on-site moisture, the indoor test adapted to the environmental conditions was carried out. Direct shear tests were performed on the high-chlorine saline soil(CL-1) and high-sulfur low-chlorine saline soil(CL-2) under different water content conditions, and the relationships between water content and shear strength parameters were obtained. Based on Geostudio, a water content-strength parameter equivalent layered calculation model for saline soil subgrade was established, and the change law of soil sample matrix suction with volumetric water content was measured by volume pressure plate test. By combining the finite element analysis of saturated/unsaturated seepage and the limit equilibrium analysis of the stability of the roadbed slope, the SLOPE/W module in GeoStudio was used to calculate and analyze the operating conditions of rainfall intensity and rainfall duration influence of saline soil subgrade slope stability. Considering the relationship function between the water content and the shear strength, the stabilities of the CL-1 and CL-2 saline soil slopes were analyzed through the establishment of an equivalent layered calculation model of the saline soil roadbed moisture content-strength parameters. The results show that when the water content is increased by 3% on the basis of the optimal water content, the cohesion of CL-1 and CL-2 decreases by 94.3% and 54.0%, respectively, the internal friction angle does not change much. When the optimal water content is reduced by 3%, the cohesion of CL-1 and CL-2 are increased by 277.1% and 89.7%, respectively, compared with the optimal water content, which has little effect on the internal friction angle of CL-2, the internal friction angle of CL-1 has decreased significantly. When the rainfall intensity is the same, the safety factor of the roadbed filled with CL-1 is more obvious than that of the roadbed filled with CL-2. The main reason is that the high chloride is more hydrophilic than the sulfate and the shear strength parameters are more affected by changes in moisture.