不同干湿循环条件下滑体土强度变化规律研究

Study on the Variation Law of Sliding Soil Strength Under Different Dry-wet Cycles

三峡库区库岸滑坡体在长期库水位升降以及周期性降雨的环境中,滑坡土受干湿循环影响其物理力学性质发生变化,从而影响滑坡的稳定性。论文以重庆市万州区塘角一号滑坡的滑体土为研究对象,研究在干湿循环状态下土体的抗剪强度参数的变化规律。试验结果表明:(1)随着干湿循环次数的增加,最大主应力与粘聚力、内摩擦角均随之逐渐降低;在经过1次干湿循环之后最大主应力与粘聚力、内摩擦角降低的幅度最大,经过3次干湿循环之后降低的幅度明显减小;粘聚力与内摩擦角在经过7次干湿循环后数值趋于稳定;(2)干湿循环幅度与粘聚力呈负相关,相同干湿循环次数条件下干湿循环幅度越大粘聚力越小;干湿循环幅度与内摩擦角在前5次循环呈负相关,5次循环后,内摩擦角受循环幅度影响很小。

In the environment of the reservoir bank landslide in the Three Gorges Reservoir area,the long-term reservoir water level rise and fall and periodic rainfall will inevitably affect the physical properties of the landslide soil,thus affecting the stability of the landslide.Based on this,the sliding soil of Tangjiao No.1 landslide in Wanzhou District,Chongqing was taken as the research object to study the variation rule of the shear strength parameters of the soil under the state of dry-wetting cycle.The test results showed that:(1)with the increase of the number of dry-wetting cycles,the principal stress difference,the cohesion force and the internal friction Angle decreased gradually;After one dry-wetting cycle,the principal stress difference,cohesion force and internal friction Angle decreased the most,and after three dry-wetting cycles,the decreasing range was significantly reduced.The cohesion and internal friction Angle tend to be stable after 7 cycles of drying and wetting.(2)The amplitude of dry-wetting cycle is negatively correlated with the shear strength.The greater the amplitude of dry-wetting cycle is,the faster the shear strength decreases.After 5 cycles,the values of the internal friction angles under three different cycle amplitudes are close to each other.At this time,the influence of cycle amplitudes is small,and the cohesion is still greatly affected by cycle amplitudes.