坡体表面点转动方位能有效揭示滑坡变形演化过程,为此自主研发了坡体表面点转动方位测定仪,实现了点转动方位定量测量。同时,构建黄土滑坡物理模拟试验,分别在滑坡体后缘、中部以及前缘地表布设2个测定仪。试验过程中采用连续长时的灌水方式来模拟灌溉水入渗对边坡变形的影响,进一步揭示了滑坡孕育过程中多点转动方位响应特征变化规律。试验研究结果表明:①随着灌溉水的不断入渗,坡体内部渗流通道不断发育、扩张,坡脚底部渗流量从24 mL/min增加到1 515 mL/min,呈双指数增长趋势。②滑坡演化过程中坡体中后部率先出现裂缝,裂缝垂直于坡面方向逐渐发展,1^#、2^#、3^#、4^#转动方位角逐渐增大,呈线性增长,随着后缘裂缝贯通后,坡体前缘裂缝逐渐发育,1^#、2^#测定仪转动方位角激增,前缘土体塑性流出。③前缘土体滑出坡体以后,坡体应力状态以及渗流路径发生改变,致使坡体中部3^#、4^#监测仪转动方向发生改变,转角方位急剧减小,中后部土体塑性流出,坡体发生二次滑动。④依据坡体表面点转动方位变化趋势,可以将灌溉型黄土滑坡演化过程概化为稳定孕育、匀速变形以及加速破坏3个阶段,其中稳定孕育阶段占整个滑坡历时时长的99.5%,匀速变形阶段占0.2%~0.3%,而加速破坏阶段仅为10~15 s,进一步表明灌溉性黄土滑坡具有明显的突发性特征。研究成果可应用于边坡滑坡变形监测。

The rotation azimuth of slope surface points can effectively reveal the evolution process of landslide deformation. We independently developed a measuring instrument for the rotation azimuth of slope surface points. Moreover, we revealed the response characteristics of multi-point rotational azimuth in the process of landslide breeding. We installed two measuring instruments respectively on the surface of the physical loess landslide model's back edge, middle edge and front edge. In the experiment, we simulated the influence of irrigation water infiltration on slope deformation with continuous long-time irrigation. Our findings manifested that: 1) with the continuous infiltration of irrigation water, seepage passages inside the slope body developed and expanded steadily, and the seepage flow at the bottom of the slope foot increased from 24 mL/min to 1 515 mL/min, showing a double exponential growth trend. 2) In the process of landslide evolution, cracks occurred firstly in the middle-to-back part of the slope, developing perpendicular to the direction of slope surface. At 1^#, 2^#, 3^# and 4^# points, the rotational azimuth increased gradually in a linear trend. Penetrating the back edge of slope, cracks developed gradually in the front edge, and the rotational azimuth at points 1^# and 2^# surged, with the soil mass been extruded. 3) The extrusion of soil in the front edge changed the stress state and seepage path of the slope body, resulting in the plummet of rotation direction at points 3^# and 4^# in the middle of slope body as well as the extrusion of soil in the middle and back edge, which gave rise to a second sliding. 4) According to the change trend of rotational azimuth of surface points, the evolution of irrigated loess landslide can be summarized into three stages: stable breeding stage, steady deformation stage, and accelerated destruction stage, of which the stable breeding stage accounted for 99.5% of the total landslide duration, steady deformation stage 0.2%-0.3%, and accelerated destruction stage only lasted for 10-15 seconds, a further sign of abruptness of irrigated loess landslide.