Research On Slope Stability Under Rainfall Infiltration Conditions

With the high-speed development of national economy,a large number of slope problems occur in many engineering fields,such as open-pit mining,railway and highway construction,water conservancy and hydropower projects.Slope failures are caused by many factors,among which rainfall is the most significant one.Therefore,studying the impact of rainfall on slope stability has important practical significances and engineering values.In view of this,this thesis takes the east slope of Jiepailing open pit as the research object,based on its engineering geology and hydrogeological background,based on its engineering geology and hydrogeological background,through laboratory test,in-situ test and numerical simulation and other analysis methods to analysis the stability of the slope under rainfall conditions.The main research contents and results are as follows:(1)Through on-site investigation and data collection of the mining area,basic data on engineering geology,hydrogeology and meteorological conditions of the mining area have been obtained.The survey results show that the surface of the east bank slope is severely weathered,and the strength of the water is likely to be low.The internal joints and cleavage are well developed,and their penetration is good.The rock structure is loose.Atmospheric rainfall seeps into the rock layer through the sandstone cracks,which softens the layer and easily causes landslides.(2)SEM was used to analyze the mineral composition of the slope rock mass;in-situ direct shear test and point load test were carried out to provide a basis for determining reasonable mechanical parameters of the slope rock mass.The disintegration test was carried out on the rock samples of the east slope.The results showed that the feldspar-quartz sandstone is relatively soft and can be softened and disintegrated when it encounters water.In the test,it showed the characteristics of faster disintegration in the early stage,slow in the middle stage,and gradually stabilized in the later stage.The quartz sandstone is hard and hardly softened by water.(3)The FLAC3D software was used to perform numerical simulation calculations to analyze the changes in pore water pressure distribution,displacement field,plastic zone,velocity field,stress field and safety factor within the slope under different rainfallconditions.The results show that: as the rainfall continues,a transient saturation zone first appeared at the foot of the slope,and the range of the transient saturation zone developed upward from the position of the slope foot and eventually stabilized;the pore water pressure of the current slope and the final slope gradually increased,and the change of pore water pressure tended to stabilize;when the rainfall lasts for 24 hours,the maximum displacement of the current slope appears near the bottom of the slope at the north end,with a maximum displacement of 6.36 cm,when the rainfall lasts for 18 hours,the final maximum displacement field area of the slope appears at the bottom of the southern slope,the maximum displacement is 6.5cm;the plastic zone increases with the duration of rainfall,and the plastic zone grows slowly in the later period of rainfall,the plastic zone of the current slope changes significantly compared with the final slope.(4)Under the condition of a rainfall intensity of 77.3mm/d,the current slope and the final slope are in a stable state when there is no rainfall.As the rainfall duration increases,the safety factor of the slope begins to decrease.When the rainfall is 6h and12 h,the current side slope The slope safety factors are 1.251 and 1.201,and the final slope safety factors are 1.230 and 1.225,respectively.At this time,the current slope and the final slope are both in a stable state.When the rainfall is 18 h,the current slope safety factor is 1.181,and the final slope safety factor is 1.203.The current slope is basically stable,and the final slope is in a stable state.When it rains for 24 hours,the current slope safety factor is 1.151,and the final safety factor of the slope is 1.193.Both the current slope and the final slope are basically stable.