花岗岩残积土非饱和特性及其边坡稳定性研究

Study on unsaturated characteristics of granite residual soil and its slope stability

降雨诱发滑坡是花岗岩残积土地区主要地质灾害之一。为研究花岗岩残积土边坡在强降雨条件下的响应,在广州市黄埔区选取了一典型非饱和花岗岩残积土边坡开展系列研究,包括现场雨量监测、固结不排水三轴试验、滤纸法试验。基于监测数据与试验结果,研究风化程度对抗剪强度及土-水特征曲线的影响规律,探究了当地不同降雨工况对现场边坡稳定的影响。结果表明,随着风化程度加剧花岗岩残积土有效抗剪强度指标均有不同程度的减小,其中,风化差异导致的有效内摩擦角变化幅度小于有效黏聚力变化幅度;风化程度差异也影响花岗岩残积土的非饱和水力特性;降雨强度与边坡安全系数的降幅呈正相关关系,而降雨历时与边坡安全系数的恢复速度呈负相关关系。该研究可为典型花岗岩残积土边坡相关工程的科学设计与灾变防控提供一定借鉴。

Rainfall-induced landslide is one of the significant geological hazards in granite residual soil areas. To investigate the response of the granite residual soil slope to torrential rain, a series of studies which include in-situ rainfall monitoring, consolidated undrained triaxial tests and filter paper method were conducted on a typical unsaturated granite residual soil slope located in Huangpu, Guangzhou. Based on the monitoring data and tests results, the influence law of weathering degree on shear strength and soil-water characteristic curve was studied, and the effect of different local rainfall conditions on the site slope stability was gave insights into. The results show that as the weathering increases, the effective shear strength parameters of the granite residual soils decrease in different degrees, and the change range of effective internal friction angle caused by weathering difference is smaller than that of effective cohesion. The unsaturated hydraulic properties of granite residual soils are also affected by weathering difference. The decrease of slope safety factor is positively correlated with the rainfall intensity, while the recovery rate of slope safety factor is negatively correlated with the rainfall duration. This study can provide some reference for scientific design and disaster prevention and control of typical granite residual soil slope related projects.