A Study On The Evolution Of Landslide Surface Morphology Induced By Rainfall Based On 3D Point Cloud Data

Since the middle of the early 20 th Century,with the explosive growth of the world's population,the scope of human activity space is gradually expanding.As a result,human engineering activities are increasingly intensified,and the transformation and destruction of the geological environment are becoming more and more serious.Landslide disasters,especially large-scale landslide disasters,occur much more frequently,resulting in increasing economic losses and casualties.China is one of the regions with the most serious landslide disasters in the world,and Zhejiang Province,because of its complex geology,topography and unique climate background,has become one of the places with the most frequent sudden geological disasters caused by rainfall in China.Therefore,it is of great significance to study the law of slope instability induced by rainfall for the prevention and prediction of rainfall landslides.In the study,indoor physical model test was used to probe into the failure process of soil slope under different rainfall conditions and different slope angles.Pore water pressure sensor and soil pressure sensor were embedded in each group of tested slopes.Cameras and three-dimensional laser scanners were used to monitor the surface deformation of slope.On this basis,comparative analysis was carried out to further study the change of internal stress,deformation and failure of soil slope under rainfall conditions,The experimental results showed that: 1).The development process of local shallow slip caused by erosion mainly consists of two stages: the formation of erosion gully on slope surface and the formation of shallow landslide;The multi-stage regressive landslide can be summarized into four stages: a)Erosion damage occurred at the foot of the slope,b)Forming a crack surface,c)The formation of small landslides,d)It produces a series of landslides and eventually leads to the complete destruction of the slope;(2)Under the condition of intermittent rainfall,the greater the rainfall intensity,the greater the peak value of pore water pressure,and the less time it takes to reach the peak value;Under the condition of heavy rain,the failure mode of soil slope will change with the increase of rainfall intensity;(3)Under the same cumulative rainfall,the peak pore water pressure of intermittent rainfall is higher than that of continuous rainfall.It shows that intermittent rainfall is easier to infiltrate and pore water pressure has cumulative effect.Under the same rainfall intensity,duration and slope,the change of rainfall pattern will not affect the failure mode of soil slope,but the intermittent rainfall is more likely to induce landslide.(4)The gentle slope is easier to infiltrate and easy to accumulate water,which leads to the high pore water pressure.The runoff erosion on gentle slopes is more serious;On steep slopes,the runoff is larger,but the infiltration is shallower,which leads to the bulk failure of slope.