Study On The Influence Of Soil Swelling On The Supporting Parameters Of Micro Piles

Micro pile is a new slope supporting structure with flexible and convenient construction,the terrain qualification requirements low,can bear large axial load and lateral load is moderate,small disturbance to the surrounding soil and environmental characteristics,the economic effect is good,But in our country the introduction of micro pile technology in a relatively short time,the micro pile force mechanism has great limitations,resulting in micro pile application in engineering practice lack of technical guidance,thus seriously restricted the development and promotion of micro pile.This paper mainly through the large-scale physical model test to study the expansion of the mound landslide occurrence mechanism of expansive soils on micro pile support parameters,through the monitoring of pile top displacement of pile,the soil pressure and the bending moment of the piles of data,analysis of data obtained from micro pile reinforced expansive landslide of the mound way the reasonable layout.The micro pile reinforced expansive mound landslide compared micro pile reinforcement loess,and strive to obtain a reliable proportional coefficient,the micro pile reinforced expansive mound landslide could cross reference the micro pile reinforcement of loess,can quickly put forward a set of landslide treatment scheme.This paper provides a theoretical basis for the application of micro piles in engineering by means of a large number of physical model tests.1.Through the simulation of rainfall and evaporation,the loading test was carried out in the landslide,and after three groups of dry wet cycle,combined with slope displacement curve know that expansive soil landslide in rainfall,the soil began to swell,when evaporation(drying),the soil began to shrink,Due to its incomplete expansion and contraction,Resulting in some small cracks in the slope,Along with the dry wet circulation,the rainfall washes the crack unceasingly,the crack starts to expand.At the same time,the erosion of rain water will take away the fine particles in the soil,which seriously destroy the soil structure.When to start loading at the top of landslide,due to the increasing load,the inflow of water inside the sliding body has been infiltrated into the branch stacking internal surface of bedrock and accumulation layer contact weak layer(near surface),the formation of rain water away the fine structure of soil,the soil becomes slack and soil strength decreases rapidly.Under the action of the load,it will start to move along the soft surface,when the load reaches a certain amount,the landslide will be produced;2.Based on the large scale physical model test,the pile top displacement,the earth pressure before the pile and the pile moment data are obtained and analyzed in the case of pile spacing of 8d and 10d,the row spacing is 5d,8d and 10d:1)The displacement of pile top,when the pile spacing is constant,with the increase of pile row spacing,pile top displacement decreases;when the load to 1516kg,pile spacing 8d,row spacing10d,the maximum displacement of the top of pile spacing is 38.632mm,when loaded to 1870kg,pile spacing 10d.row spacing 8d and 10d the maximum displacement of the top of pile spacing is 42.582mm,37.83mm.2)in front of the pile soil pressure,mainly when the pile spacing is constant,with the increase of pile row spacing,pile the soil pressure decreases,5d pile row spacing pile under the soil pressure maximum,when loaded to 1516kg,the pile spacing is 8d,row spacing 10d,three rows of pile stress ratio is 1:0.674:0.554;when loaded to 1870kg,pile spacing 10d,row spacing 8d and 10d three rows of pile stress ratio are 1:0.738:0.638 and 1:0.709:0.615.3)the bending moment of the piles,through the pile bending moment curve found that 40cm from the top of the pile and pile distance 60cm respectively at the maximum bending moment of pile,and 60cm from the top of the pile is near the sliding surface.that makes the micro pile in the sliding surface design within consideration.3.This paper presents for the first time layout the longitudinal and lateral as "X" type of coupling beam in the top of the micro pile,through the experimental study and compare with the pile top displacement of only longitudinal coupling beam decreased 14.4%.can reduce the anti sliding section bending moment of pile deformation,and the performance as a whole three row pile bearing pile of landslide thrust.4.Compare the micro pile reinforcement of loess landslide with the micro pile reinforced expansive landslide and considering the actual situation of engineering.found the reasonable ratio coefficient of micro pile reinforcement of loess landslide and the micro pile reinforced expansive landslide is 1.3?1.5.