渗透对非饱和原状黄土高边坡土压力和水平位移影响的试验研究

TEST STUDY ON INFLUENCE OF IMMERSION ON EARTH PRESSURE AND HORIZONTAL DISPLACEMENT OF HIGH SLOPE OFUNSATURATED INTACT LOESS

通过现场原位试验,对非饱和原状黄土垂直高边坡在坡顶浸水渗流作用下的土压力变化及切坡临空面位移进行现场试验研究,试验结果表明:(1)切坡坡顶浸水后,土压力强度增加迅速,截止滑坡前,土压力强度比浸水前增大约4倍;(2)滑坡发生后,实测的滑移面形态及剪出口位置在切坡高度H的1/3处,而并非发生在坡脚处;(3)非饱和原状黄土垂直切坡的土压力强度是由下滑土体自身的剩余下滑推力引起的,这与经典土压力理论有一定差异;(4)土压力强度变化与边坡临空面水平位移没有对应关系,也是非线性的;(5)在切坡浸水渗透试验过程中,土压力强度变化过程可划分为3个阶段:第一阶段滑动土体的力学性质改变阶段,第二阶段滑动土体的整体变形阶段,第三阶段滑动土体的整体滑移阶段;(6)对于非饱和原状黄土垂直切坡,本次实测坡顶水平位移在10 mm时滑坡,可考虑对于该力学特性的黄土水平位移10 mm为预警值。

By the field test,influences of immersion on the top of slope about earth pressure of unsaturated intact loess and displacement of free face of slope are studied.The results show that：（1） When the top of slope is soaked,the earth pressure strength increases rapidly;the maximum earth pressure strength of the soaked slope is 4 times of intact slope before the slope landslide.（2） After the slope landslide,shear outlet of landslide is at the one third of the slope height rather than the toe of slope.（3） Earth pressure strength of unsaturated intact loess is mainly produced by residual downslide thrust.（4） The displacement of free face of slope which is nonlinear relationship with earth pressure and the displacement of free face of slope is not caused by earth pressure.（5） In the process of water immersion,changing process of earth pressure can be divided into three stages：the first stage is changing stage of mechanical properties of slide earth body;the second stage is integral slippage stage of slide earth body;the third stage is integral deformation stage of slide earth body.（6） For the vertical cut slope of unsaturated intact loess,ultimate alarming value of the horizontal displacement is 10 mm;if the horizontal displacement of vertical cut slope is more than 10 mm,the slope would probably evolve into a landslide.