Research Of Arch Effect Between Anti-slide Piles And Soil Pressure On Pile Sheet

At present, the anti-slide piles are widely applied in the field of geotechnicalengineering such as the railway, highway, hydropower, municipal and miningengineering due to its advantages of small masonry, large anti-slide resistance, goodretaining effect and so on. With the extensive application of the anti-slide piles, thedesign ideal and computation theory have been continuously developed. However, acommon consensus has not been reached due to the complexity of the rock and soilproperties, the arching mechanism of the anti-slide pile, the calculation of soil pressureon the holding sheet and the retaining effect of large landslide with double-row piles.For this purpose, deep analysis was made in this paper on the distribution law of thesoil pressure on the pile sheet and the force transmission mechanism of the double-rowpiles based on the analysis of the arching effect of civil engineering by takingfollowing research subjects as the basis, including“Research on Three-dimensionalSoil Arch Effect of Cantilever Anti-slide Piles”(No:50878218), a subject supportedby the National Natural Science Foundation of China, and “Demonstration ofOptimization Technology Integration for Regional Spatial Planning and Land Use ofThe Villages and Towns”(No.2012BAJ22B06), a subject under the “National KeyTechnology Development and Research Program during12th Five-year Plan”. Themain work and research conclusions are as follows:(1) Based on the analysis of the arching effect of soil body, the anti-retainingforce on the anti-slide pile was firstly regarded as the distributed force acted on thehalf-plane boundary, and then the additional stress in the soil body behind the piles wascalculated with the elasticity theory so as to reveal the formation mechanism of thearch effect between piles. On this basis, the calculation model and formula for rationalanti-slide pile spacing and arch axis were established, the possibility of the existence ofthe rock arch between piles was analyzed, and the calculation model and formula forthe rock arch was also set up.(2) A large outdoor thrust test was designed according to above-mentionedformation mechanism of the soil arch between piles. The test was carried out by twoschemes, i.e. hanging sheet in front of the pile and fabricating sheet behind the pile,deep study was made for two schemes on the soil arch effect between piles and thevariation law of the soil pressure on the pile sheet. On this basis, the calculation model for soil pressure on the holding sheet between piles was established and thequantitative calculation formula for soil pressure on the holding sheet between pileswas derived. In addition, comparison was made with the measured results, the standardmethod (the silo method) and the traditional unloading arch method.(3) Limited to the limitation of the large outdoor test device, an indoor modelthrust-pile test was designed in this paper based on the similarity principle, and anoverall and systematical study was made into the soil arch effect between the anti-slidepiles and force transmission mechanism. On the basis of the large outdoor tests,additional tests of the soil arch effect between piles and the thrust load transmissionunder the condition that the spacing of the cantilever piles is larger than the calculatedrational one and additional study of the soil arch effect behind and in front of theburied anti-slide piles were carried out. On this basis, study was also made on the soilarch effect between piles, the soil arch effect between rows in different spacing of thedouble-row piles as well as the force transmission regularity of the piles.(4) Based on the indoor model test, deep analysis was made in this paper on theforce transmission mechanism of the double-row piles, the principle for determiningthe rational row spacing of the double-row piles was put forward, in the meantime, thethrust and anti-slide resistance equations for each row of the double-row piles wereestablished according to the Janbu analysis method and the theory of elastic foundation,and the calculation formula for analyzing the pile-body displacement and internal forcewith full-section method and the sectional iteration method was proposed; and finally,the optimization design method for the double-row piles was put forward according tothe fuzzy evaluation theory and by taking the stability safety factor, the thrust of eachrow of piles and the thrust difference between two rows of piles as the objectivefunction.(5) On the basis of the above-mentioned study of the soil arch effect betweenpiles and the soil pressure on the pile sheet, a long-time observation for the soilpressure on the pile sheet was carried out and deep study was made on the creep effectof the soil arch between piles and the time effect of the soil pressure on the pile sheetby further utilizing the large outdoor test and indoor model test.