Research Of Interaction Mechanism Between Accumulation Landslide And Anti-sliding Pile In Model Test

Anti-sliding pile is a large cross section lateral load pile which embedded in the stable bedrock. It deforms jointly with the soil to resist the residual thrust load. A series of as-sumption in the interaction model calculation makes a different to the real situation. A study of interaction mechanism between landslide and anti-sliding pile should be carried out.Firstly, the displacement, soil pressure, pile deformation and deformation failure process are analyzed in the model test. Then, a numerical simulation is adopted to supple-mentary analyze the three dimensional soil arch effect. Last, a calculation model consider-ing the friction arch and end bearing arch is carried out. The main results are listed below:(1) The PTV particle image method is used to process the displacnment field. The typ-ical tracer point displacement time history curve in non-pile test can be divided into initial creep stage, extrusion deformation stage, the stage of plastic deformation and the whole sliding phase. While the displacement of the back surface in in-pile test accounted for about 10% of the non-pile test in the same place.(2) The distribution type of soil pressure is different in rear, front and cencral part of the model in non-pile test. At the back of the model,the soil pressure is a parabolic distribu-tion pattern, when it comes to the middle,5～10 cm below the surface is triangular distribu-tion pattern,10～25 cm is rectangular distribution pattern,25～30 cm is inverted triangular distribution pattern. The distribution type of soil pressure at the rear of the main section of model is a parabolic distribution pattern in in-pile test. The pressure value and distribution in the middle part of model change under the influence of the pile. The pressure value re-duced 80～95% at the same load. Although the distribution pattern is still the parabolic dis-tribution, but the resultant force pointpoint raises 20% of the cantilever length.(3) The pressure distribution behind pile is parabolic distribution in the whole loading test, the maximum point under different load levels differ. Resultant force point firstly de-crease then remain unchanged. Before the pile,18 cm depth below the surface, pressure distribution is a parabolic distribution and absolute value is only 5% of the same place be-hind pile. Under 18cm depth, pile soil pressure value remains 0 in the whole test.(4) In the non-pile test, the deformation is controlled by the model shape, the soil slides to the free face under the load. While in the in-pile test, the soil slips up along the main di-rection behind the pile, a local damage occur in this test. Than one landslide damage range in the working condition of pile, pile model after cut out breakdown point by the steep slope deformation after the place to pile, significantly reduce disturbance deformation area of damage. The movement area decrease obviously under the influence of pile.(5) The soil arch effect between pile occurs obviously in the test. There is a order when the effect begins. The soil arch effect firstly occurs in the shallow depth of the model. With the increase of load, the effect can be finded in the 12～24cm depth. The effect remain until the test end. After quantitative calculation of pressure, end bearing arch and friction arch are jointly resist the thrust. Under the 1068N load, the end bearing arch accounted for 64.3% of the load, friction arch accounted for 31.3% and the front soil before the pile resist 4.4%.The law of distribution of soil arch effect in vertical direction is analyzed in numerical simula-tion. The minimum principal stress arch and the maximum principal stress arch are wide-spread in vertical direction. With the increase of depth, the arch rise of friction arch de-creases, the bearing raion of friction arch increase, the ratio of end bearing increase slowly, the ratio of soil front the pile decrease. In general, the soil arch effect between piles enhance with the depth increasing.Based on Ito. Plastic deformation theory, a calculation formula considering the jointly role of friction arch and end bearing arch is carried out. The results show that, the friction arch plays a leading role in bear the landslide thrust load, when the cohesive force of soil increases, the boundary spacing increase linear and the bearing ration of friction arch de-creases slowly, when the angle of soil increases, the boundary spacing increase like a a in-ward curve and the bearing ration of friction arch increases linear. Consider a combination of both arch, the pile spacing of majiagou is 4.68 m.(6) The Majiagou Landslide is in unstable deform stage according to the model test results if not considering the influence of river and creep characteristics of soil. When the anti-sliding pile is built in the landslide, the Majiagou Landslide will be stable. If consider-ing the influence, this law will not apply.