Study On Instability Process Of Loess Filled Slope Under Different Protective Measures Under Hydrodynamic Force

Due to the loose loess structure and strong water sensitivity in the Loess Plateau region of China,and the extreme rainfall and weather in the region,the human activities such as irrigation and water storage are increasingly intensified,resulting in frequent regional geological disasters,which has brought human production and life and engineering construction activities.A series of questions.In recent years,with the promotion and implementation of the country's western development strategy and the “Belt and Road” policy,human engineering activities in the northwest loess area have become increasingly frequent,such as “Gugou Baoyuan”,“Pingshan City”,and “Planting Land” Other major projects have been launched in the Loess Plateau.During the implementation of these projects,a large number of fill slopes are inevitably generated due to excavation and landfill operations.These slopes use different protection measures during protection,and their stability is not yet clear.The slope protection effect needs to be evaluated.Therefore,it is urgent to study the instability process and mechanism of different protection measures under the action of hydrodynamics on loess-filled slopes,and to evaluate the impact of different protection measures on the stability of loess-filled slopes.Many scholars have studied the deformation and failure process of slopes under the action of hydrodynamics based on laboratory tests,model tests,field tests or numerical simulation tests,but there are not many studies on the instability process of loess-filled slopes under different protective measures.Therefore,this paper takes the loess high fill slopes with different protective measures as the research object,and establishes indoor models of the loess high fill slopes with different protective measures through indoor physical model tests,and simulates different protective measures under the action of rainfall and groundwater uplift The process of instability and failure of high loess-filled slopes in China,using the data of pore pressure sensor,moisture sensor and 3D laser scanner to obtain the data of slope displacement,pore pressure and water content,in order to summarize the instability of various slopes for the failure mode,the instability mechanism of loess high fill slope was analyzed,and the numerical simulation was carried out on the basis of model test using Geo-studio software.The following conclusions were obtained:(1)The degree of damage and the type of damage of slopes with different protection types under rainfall conditions are different.Slopes treated with leveling slopes are most vulnerable to damage,and under heavy rainfall conditions,slope erosion,local instability,and even overall instability damage are prone to occur.The slopes that are protected by gradually slowing down slopes are not easy to lose overall stability,but the erosion and destruction of the slopes by the water flow are more serious than those of other protection types.Slopes treated with steps and drainage channels are likely to cause partial block collapse along the lateral drainage channels,and the sliding surface is generally deep.(2)The magnitude of pore pressure response in deep soils,the development characteristics of tension fissures and the differences in slope confluence are the fundamental reasons that cause different slope instability processes and models under different protective measures.In actual protection engineering,attention should be paid to reducing the response of the slope soil,preventing the development of deep tension cracks,and weakening the confluence of the slope.(3)The instability mode of loess-filled slopes under water uplift is the flow slip caused by the liquefaction of loess at the bottom.Compared with the rainfall-induced landslide,the damage to the slope body is greater,the sliding surface is deeper,and the sliding distance of the landslide is farther.Softening and liquefaction of the bottom soil and reduction of effective stress are the main reasons for slope instability induced by groundwater uplift.(4)The numerical simulation results show that the slope with progressively slower slope for protection has a larger change in pore pressure at the foot of the slope and a wider change area,but its maximum shear strain is smaller than that of the other two types of slopes.,And the maximum shear strain contour is relatively loose,and there is no area where the contour changes rapidly.The slope pressure and the maximum shear strain change of the slope treated by the step and drainage channel are both related to the lateral drainage channel on the slope.The soil pressure near the drainage channel is higher and the shear strain variation curve is more dense.Under the action of groundwater uplift,high pore pressure and high shear strain area will be formed at the foot of the slope,making the foot of the slope the area most prone to shear failure and slippage.