| Landslide is a kind of geological disaster,which is widely developed on the earth’s surface.As an effective anti slide measure,anti slide pile has been widely used in landslide treatment.In traditional anti slide pile reinforcement effect analysis,the geotechnical materials are regarded as ideal elastic-plastic body and ignoring the creep characteristics of rock and soil,which makes it impossible to consider the deformation process of landslide is phasic with the creep of rock and soil.The rheological properties of rock and soil not only affect the deformation and evolution of landslide,but also affect the effect anti slide pile.The research on the reinforcement effect of anti slide piles in different deformation stages of landslide can provide guidance for the treatment of landslide.Majiagou Landslide is a typical accumulation landslide with creep property,which is located in the Three Gorges Reservoir Area.This paper firstly introduces the engineering geological conditions and deformation characteristics of the landslide.The physical and mechanical parameters of landslide rock mass are obtained by laboratory experiments,and the creep behavior of sliding soil is deeply studied.on this basis,the deformation process of landslide is studied by numerical simulation,and the evolution stage of landslide is divided.Then,the numerical simulation of the anti slide piles is carried out at different deformation stages of landslide,and the reinforcement effect of anti slide piles in different deformation stages is studied.Finally,based on the physical model test of landslide,the reinforcement effect of anti slide pile in the initial deformation stage of landslide model is studied from the aspects of landslide stress field,strain field,temperature field and the stress characteristics of anti slide piles.The main research contents and results are as follows:(1)The engineering geological conditions and deformation characteristics of Majiagou landslide are analyzed.The physical and mechanical parameters of landslide rock mass are obtained through experiments,and the creep behavior of sliding soil is deeply studied.Results show:(1)The conventional strength parameters of landslide bedrock cohesive force C is 8.4MPa,the internal friction angle is 40.2°.The conventional strength parameters of sliding soil cohesive force C is 34 MPa,the internal friction angle is 23.6°.The conventional strength parameters of slip zone soil cohesive force C is 31 kPa,the internal friction angle is 21.2°.(2)Landslide slip zone soil show strong creep characteristics.The long-term strength parameters of slip zone soil cohesion C and internal friction angle values are 16.7kPa and 11.8 degree respectively,which decreased by 46.1% and 44.3% compared to the conventional value.Cvisc constitutive reflect the rheological properties of the sliding zone soil model,rheological parameters were determined.(2)Based on the creep characteristics of landslide,the whole deformation evolution process of landslide is studied by numerical simulation method.Results show:(1)The landslide deformation increases with the prolongation of creep time.The whole deformation and evolution of the landslide can be divided into initial deformation,the constant speed deformation and accelerated deformation stage,and the landslide failures when it enter accelerated deformation stage;(2)The landslide is mainly sliding along the sliding zone.Slip zone is the boundary of vertical distribution of landslide deformation.The evolution of the sliding shear zone reflects the forming process of the potential sliding surface of the landslide,Controlling the deformation of landslide.(3)The deformation of Majiagou landslide is mainly horizontal displacement.and the horizontal displacement of landslide is about 93% of the total displacement.(4)The deformation of the middle part of the landslide is large,while the deformation of the front and rear is small.The deformation of the landslide has spatial difference.(5)The evolution of different parts of the landslide are roughly the same in time,but the time of different parts entering a certain deformation stage are slightly different,there is a certain time difference.(6)The stability coefficient of landslide is 1.33,1.254,1.163,1.067 and 1.028 respectively when it’s in the initial deformation stage,the initial stage of the constant velocity deformation,the middle stage of the constant velocity deformation,the late stage of the constant velocity deformation and the accelerated deformation.The steady state of the landslide is gradually changed from stable to unstable,and it is close to the critical state when the landslide begin to failure.(3)The reinforcement effect of the anti slide pile in different deformation and evolution stages of landslide is studied.Based on the research of landslide deformation and evolution process,the numerical simulation of the anti slide piles is carried out at different deformation stages of landslide,and the reinforcement effect of anti slide piles in different deformation stages is studied from the aspects of stress field,strain field,deformation rate and stress of anti slide pile.Results show:(1)With the evolution of the landslide,the landslide thrust increases gradually,and the bending moment and deformation of the pile are also gradually increased.(2)The deformation of landslide respectively decreased by 50.5%,31.9%,14.7% and 3.1% when the anti slide pile is applied in the initial deformation stage,the initial stage of the constant velocity deformation,the middle stage of the constant velocity deformation and the late stage of the constant velocity deformation of the landslide.The earlier the anti slide pile is applied,the better control effect of landslide deformation.(3)The deformation rate of landslide respectively decreased by 80.4%,66.9%,53.4% and 39.9% when the anti slide pile is applied in the initial deformation stage,the initial stage of the constant velocity deformation,the middle stage of the constant velocity deformation and the late stage of the constant velocity deformation of the landslide.The earlier the anti slide pile is applied,the better control effect of the deformation rate.(4)The anti slide pile effectively prevents the sliding shear zone from extending from the back pile area to the front of the pile,restricting the formation of potential sliding surface.The earlier the anti slide pile is applied,the better the control effect on the potential sliding surface of landslide.(4)The stability of the landslide before and after the application of anti slide piles is calculated by rigid limit equilibrium method.Calculation results show:The landslide stability coefficient respectively increased by 0.261,0.221,0.178 and 0.136 when the anti slide pile is applied in the initial deformation stage,the initial stage of the constant velocity deformation,the middle stage of the constant velocity deformation and the late stage of the constant velocity deformation of the landslide.The stability improvement of Landslide is the largest when the anti slide pile is applied in the initial deformation stage,while the stability improvement of Landslide is the smallest when the anti slide pile is applied in the late stage of the constant velocity deformation of the landslide.The earlier the anti slide pile is applied,the better effect of landslide overall stability improvement.(5)Through the physical model test,the interaction between the anti slide pile model and the landslide physical model is analyzed,and the reinforcement effect of the anti slide pile in the initial deformation stage is studied from the stress field,strain field,temperature field and so on.Results show:(1)The earth pressure behind the pile body is much higher than the earth pressure before the pile,the anti slide pile effectively prevents the transmit of the landslide thrust from behind the pile to before the pile.With the evolution of landslide,the earth pressure behind the pile distribution along the depth by linear type gradually evolved into S,finally evolved into parabolic type.The soil pressure behind the pile along the horizontal direction shows inverted arch type distribution.The arch curvature reflects the strength of the soil arching effect,and the arching effect is most significant at the depth of 18 cm.The distribution law of soil pressure along the depth and horizontal direction shows the evolution process of three-dimensional soil arch.(2)The deformation of landslide model is mainly horizontal displacement.The deformation behind piles is very large,while the deformation before the pile is very small.The anti slide pile not only restricts the development of landslide deformation,but also improves the overall stiffness of the landslide.The anti slide pile can prevent the Integral sliding of the landslide,but the local shallow layer failure occurs.The deformation rate of the sliding body has the characteristics of abrupt change.(3)With the development of landslide deformation,the force of anti slide pile increases gradually,and the effect of landslide thrust on the anti slide pile is obvious.The anti slide pile changes the transmission mechanism of the landslide thrust and bears most of the landslide thrust.(4)The distribution law of the temperature field shows the formation mechanism and evolution process of soil arch between piles.The soil arch structure makes the vertical landslide thrust into the lateral thrust effectively and acts on the pile body,so that the anti slide effect of the pile can be exerted. |
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