滇西典型膨胀土滑坡稳定性分析

Stability analysis of the typical expansive soil landslide in western Yunnan Province

滇西山前地带广泛分布着一层具有弱膨胀性的粉质粘土,在降雨条件下常诱发滑坡灾害,成为当地一种典型的滑坡灾害类型。从土体非饱和特性出发,通过土体吸力测试,提出了基质吸力-含水量土水特征关系,确定了饱和含水量在37%左右,残余含水量约3.5%,进气值约190 kPa;三轴力学试验取得了非饱和土强度参数,土体吸力内摩擦角为4.3°;建立了饱和—非饱和渗流数值模型,对不同雨强条件下的滑坡失稳过程、机制进行了模拟。模拟结果为:强降雨引起滑坡稳定性明显降低的时间效应为2 d左右,雨强16 mm/d以上,持续降雨3 d后滑坡失稳滑动,雨强6 mm/d以下的降雨对滑坡稳定性没有明显影响。为该类型滑坡灾害的防治提供了重要科学依据。

There is wide distribution of silty clay layers with weak expansion in piedmont area of western Yunnan in China.The rainfall-induced landslides are so frequent that huge losses occur in relevant traffic routes and construction facilities.It becomes one of the most typical landslide hazard in the area.Based on the study of the characteristics of the unsaturated soil,important progress has been made.The soil-water characteristics between matrix suction and water content was proposed by the soil suction test.The saturated water content is about 37%,the residual water content about 3.5%,the air entry value about 190 kPa.The suction internal friction angle 4.3° of the unsaturated clay was achieved by the triaxial mechanical test.The saturated-unsaturated seepage numerical model has been established to simulated the courses and mechanisms of this kind of landslide instability under the conditions of different rainfall intensities.The time effect of the instability during the heavy rain is about 2 day when the landslide stability is significantly reduced.The landslide may become unstable and slide after three days of the continuous heavy rain at 16 mm/day.There is no significant impact on the landslide stability at the rain less than 6 mm/day.The results can be taken as the important scientific basis for prevention of this type of landslide disaster.