| The Meiliishi 3#landslide is located in the meilishi village of Deqin County,Yunnan Province in southwestern China.The landslide body is located on the left bank of the lancang River.It is one of the many landslides in the basin and belongs to the typical high landslide.At present,there are a large number of cracks in the slope table.With the infiltration of rainfall,the landslide body has signs of resurrection,and the slope body has obvious signs of deformation.If the landslide is unstable due to rainfall,it will constitute a huge threat to the construction and safe operation of the hydropower stationIn this paper,the footrills of the Meilishi 3#landslide are surveyed and the slope cracks are investigated.It design the indoor rainfall infiltration experiment according to the typical cracks,which studied how the combined cracks and the primary-secondary development modes in the deposits affecting the process of rainfall infiltration.At last,a numerical model was constructed to compare the infiltration differences with the results of indoor rainfall infiltration test.The main research results have been obtained:(1)The Meiliishi 3#landslide deposit belongs to a high-altitude ancient landslide on the upper bank of the Lancang River.The elevation of the landslide body is mainly between 2700~3250m,the lateral span can reach more than 690m,the longitudinal span is more than 1000m,and the left and right sides of the slope are large.Large gullies are distributed along the two boundaries of the slope,the trailing edge forms a steep circular chair-like shape,the slope is 33~38°,the landslide is mainly cut out from the leading edge,the cut height is 600m from the normal water level,and the overall landslide amount is about 1030×10~4m~3,it is a huge scale.(2)According to the crack survey,the cracks are dominated by N30°~60°E and S30°~80°E.The slope deformation is mainly concentrated on the front edge of the slope and the gully on both sides.The front edge develops a large number of tensile cracks and collapses,and the disintegration phenomenon is more obvious.The number of cracks in the middle are less,slip and cracking are the mainly,and the steep is at the trailing edge mostly.(3)Select the typical cracks on the slope to carry out the indoor infiltration test.The differences of different crack development on the infiltration process of the deposits are obtained which based on the matrix suction,pore water pressure,water content and the infiltration process of the wetting front.The results are as follows:(1)the wetting front of X-type fractures is introgressed by three-stage morphology;the wetting front of Y-type fracture is arc-shaped infiltration;the lower and middle parts of parallel fractures are gently infiltrated;the wetting front of the feather crack infiltrated as the shape of"nipple".(2)The matric suction is characterized by a steep cliff-type decline,which is independent of the rainfall time and only related to the arrival time of the wetting front.(3)The change of water content at the top of the slope is related to the rainfall time.The value immediately increases after rainfall,and then the curve falls back.The middle and the bottom of the slope are affected by the accumulation of rainwater.The numerical value shows cumulative growth and cumulative effect.(4)The pressure is prolonged with the rainfall time,and the monitoring value is increasing.The central point of the main crack is always change earlier than the top point of the slope.The water accumulated under the crack will strengthen the bottom to make the value change.(4)The infiltration stage of every fracture model are as follows:the X-fracture model is in the surface wetting stage?the water supply recharge infiltration stage?the middle and lower layer diffusion infiltration stage?the bottom lateral infiltration stage;the Y fracture model enters the infiltration process can be roughly divided into the infiltration wetting stage?the vertical strong infiltration stage?the middle and lower layer diffusion infiltration stage?the bottom lateral infiltration stage;the infiltration process of the primary-secondary parallel fractures can be roughly divided into the surface wetting stage?Local intense vertical infiltration stage?stable gentle infiltration stage?bottom lateral infiltration stage;the parallel fracture infiltration process is surface wetting stage?local strong vertical infiltration stage?stable gentle infiltration stage?bottom lateral inflow Infiltration phase.The intrusion depth affected by X-type cracks and Y-type cracks is about 40cm in parallel,and the depth of impact is not more than 20cm.The depth of impact of plume cracks can reach about 60cm.(5)Using the Geo-Studio software Vadose/W model to simulate the rainfall infiltration process of the Meilishi 3#landslide based on the saturated-unsaturated seepage theory,the results obtained are similar to the results of the laboratory test. |
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