Study On The Bearing Capacity Of The Existing Pile Anchor And The Stability Of The Landslide In The West Of Min River Electrochemical Plant

The landslide in the study area is located in the west of the plant area of Sichuan Min River electrochemical Co.,Ltd.,Tuanjie village,Fushun Township,Mao County,Sichuan Province,with a volume of about 94.2×10~4 m~3,belonging to a medium-sized accumulation layer landslide.Due to the construction and excavation of the plant,the toe of the front slope is free,and the anchor cable anti slide pile was applied in 2011.In2015 and 2018,the landslide experienced a large deformation again.In 2011,the anchor cable failed.In September 2018,the emergency anchor cable was implemented.At present,the emergency anchor cable in 2018 and the anti slide pile in 2011 play the role of anti slide.The landslide is still slowly deformed.Since the formation of the landslide,the scale of the landslide has been increasing from the initial 35.2×10~4 m~3 to the current 94.2×10~4 m~3.In this paper,the bearing capacity of the existing pile anchor and the stability of the landslide in the west of the electrochemical plant are studied.On the basis of several previous investigations,a series of field investigations were carried out.In order to provide the foundation coefficient parameters for the analysis of the bearing capacity of the pile anchor,the indoor confined compression test is carried out.Through the analysis of the bearing capacity of the pile and anchor,the limit equilibrium method and the strength reduction method are used to analyze the stability of the slope,and the following results and understandings are obtained:(1)The core obtained from the field drilling is sampled at a certain depth,and the lateral limit compression test is carried out to obtain the foundation coefficient of the landslide mass.The size correction and settlement amplification are carried out to obtain the foundation coefficient of each depth.It is found that the foundation coefficient increases gradually with the depth,and the proportion coefficient of the horizontal foundation coefficient is 2.36 MPa/m~2.(2)Through on-site inspection,the working behavior of anti slide pile with anchor cable is known.The bearing capacity of anti slide pile with anchor cable and without anchor cable is analyzed.When there is no anchor cable and only anti slide pile works,the bearing capacity of anti slide pile based on anti slide pile structure and foundation strength is analyzed.The bearing capacity of 1-1 profile anti slide pile is about 2000 k N(the single width resistance is 400k N/m),and that of 3-3 profile anti slide pile is about5000k N(the single width resistance is 1000k N/m).When the anchor cable plays a role,the bearing capacity of pile anchor is analyzed based on the structure of pile anchor and the strength of foundation.The bearing capacity of 1-1 profile anchor cable anti slide pile is about 8500k N(the single width resistance is 1700k N/m),and that of 3-3 profile anchor cable anti slide pile is about 9000k N(the single width resistance is 1800k N/m).(3)The transfer coefficient method is used to back calculate sections 1-1,2-2 and3-3 in the rainy season of 2018 to determine the strength parameters of the sliding belt required for the subsequent limit equilibrium calculation.At this time,the anchor cable fails and only the anti slide pile plays a role(the single width resistance of profile 1-1 is400k N/m,the single width resistance of profile 3-3 is 1000k N/m,and there is no anti slide pile on profile 2-2).The stability coefficients of the three sections are 0.940,0.897and 0.992 respectively when the shear strength parameter c=14.5k Pa and?=20°.It is consistent with the state of the slope at that time.(4)The back calculation is used to obtain the strength parameters of the sliding belt.The stability analysis is carried out for the sections 1-1,2-2 and 3-3 by using the transfer coefficient method.The bearing capacity of the pile anchor(the single width resistance of the section 1-1 is 1700k N/m.The single width resistance of the section 3-3is 1800k N/m,and the anti slide pile without anchor cable on the section 2-2.)obtained from the above analysis is taken into account.The results show that the stability of the whole slope is poor,especially the section 2-2 is the most dangerous.(5)The strength reduction method is used to simulate the landslide.In this paper,the tension of anchor cable,bending moment and shear force of pile body in anchor cable anti slide pile are equal to the internal force in(2)analysis of pile anchor bearing capacity.The following conclusions are obtained:(1)Different judgment criteria(numerical calculation,displacement and bearing capacity of pile anchor)are used for landslide instability.The stability coefficient obtained is the largest when the calculation is not convergent.Finally,the smaller value of the stability coefficient is selected as the final stability coefficient.(2)Landslide is basically stable under natural condition and unstable under rainstorm condition.If effective support is not carried out,the landslide may continue to develop upward until it becomes unstable under the action of continuous rainstorm or occasional earthquake in the future.