The Study Of Anti-Slide Mechanism And Internal Forces Of Micropile Based On Numerical Simulation

Landslides are the most common geologic hazards in China.Micropile is miniaturize engineering measure of retaining structures which can improve the effectiveness of landslide treating.In order to popularize the application of micropile in landslide treating,it is necessary to analysis anti-slide mechanism and internal force method of MicropileThrough the unconstrained single rank and double rank of micropiles tests with the constrained double rank of micropiles tests based on numerical simulation.The anti-slide mechanism of micropile were drawn through the test results which can proposes a set of internal force analysis methods.Include deformation and failure characteristics,soil stress distribution characteristics,internalforce and anti-slide PerformanceThe deformation and failure characteristics of micropile is bending deflection at the anchorage micropile end of 2/3 as the origin,and the separation deformation between micropile with soil;the landslide thrust transference between the soil and micropile result in soil-arching effect,the development of soil plastic zone is related to soil-arching effect.The soil between the micropiles with micropiles forms a consolidated system to resist the loadThe soil stress on the side of the micropile is distributed as "triangle" along the slip surface;when the micropile top is not constrained,the landslide thrust are transferred through the soil between the micropiles,the landslide thrust of the first row micropile is bigger than the second row micropile;when the micropiles top is constrained,the Coupling Beams can transfer the load,and the landslide thrust of the first and second row of piles is averageThe internal force distribution feature of the single rank and double rank of micropile are basically the same.Different from the anti-slide pile,which relies on its own stiffness to balance the landslide thrust,The stiffness of the micropile is not enough to resist the deformation caused by landslide thrust when it is larger than the soil.The point of inflection and the zero shear stress point of the micropiles move up under the effect of horizontal load,the bending deformation of the loading end of micropile is inconsistent along the depth,There will be complex pile-soil interaction between pile and soil.when the micropiles top is unconstrained,the first row of micropiles loses the bending and shear capacity first compared with the second row;when the micropiles top is constrained,the first row of piles and the second row of piles basically lose the bending and shear capacity at the same timeFor the anti-slide Performance of micropile,increasing the rank of the micropile can effectively increase the area of the micropile anti-sliding system to bear more landslide thrust The horizontal critical load of unconstrained double rank of micropiles is increased by 16.57%compared to single rank of micropiles;When the micropiles top is constrained,the horizontal critical load and the limiting load did not change,Coupling Beams reduce the horizontal displacement of the micropiles at the slip surface,the first row of micropiles decreases by about 4%and the second row of micropiles decreases by about 6%decline,which extend the process of plastic failure of model.The anti-slide mechanism of micropile mainly includes shear resistance,bending resistance and pile-soil interaction.Under the same load,The phenomenon of soil-arching effect caused by different pile spacing is different.Appropriate pile spacing can give full play to the anti sliding ability of micropiles.The limit equilibrium equation is established based on the section strength at the foot of the soil-arching,then derive the formula of the maximum shear strength of the soil-arching.Last,the judgment formula of the rational pile spacing is deduced:(?)(?).