Study On The Formation Mechanism And Influence Factors Of Soil Sliding Shear Band Between Unbaffled Cantilever Piles

With the development of our national economy, the project constructions areincreasingly rising. High slope, deep excavation and other geotechnical engineering arebecoming more and more common. Landslide, Instability of foundation pit and othergeotechnical engineering problems are increasing. Geotechnical disasters such aslandslide, collapse, mudslide occurred frequently. As a kind of effective structure,anti-slide pile has anti-sliding ability, high safety, convenient and fast construction, onthe slope with the advantages of small disturbance and other advantages, it is widelyused in the field of geotechnical engineering. In recent years, research on anti-slide pileis more focused on the aspects of the soil arching effect and optimizing design of thepile, stability of soil and piles research is relatively few. Investigations of thecantilevered anti-slide pile are limited on the buckling mode and failure state, but theprocess of localized shear band formation and development in the soil progressivefailure, the mechanism of sliding instability of the soil between piles and the influencefactors of soil stability are not studied intensive. Therefore, this article relied onChongqing Hundreds of Engineering Technique Talent Program "Cantilever Anti-slidePile of Three-dimensional Soil Arching Effect and The Dynamic Catastrophe research”.Take unbaffled cantilever anti-slide pile as the research object, using theoretical analysisand numerical simulation method, From the process of localized shear band formationand development of the soil between piles, research the slump instability mechanism ofsoil between piles.Determine the position of slip surface and the space distributionfeatures, and combined with strength reduction method to analyze the stability of thesoil between piles. Also study the he influence of factors on the stability of soil betweenpiles about cohesion, internal friction angle, the size of the airport surface, and the pilesoil contact properties. And use the research results comparing with the experimentalphenomena.The main research contents and conclusions are as follows:1）Through analysis compared with the experiment, FLAC3D can effectivelysimulate the process of instability of soil between cantilever piles. The soil betweenpiles shows the progressive instability feature, along with the phenomenon of localizedshear band. Through the analysis found that the shear band is a localized deformationstrip zone with a certain width, formed at the bottom of piles close to the airport surface,and develop to the surface of soil according to a certain angle until the shear band cut-through, the soil between piles appears sliding instability.2）Based on the research about the formation and development of localized shearband of soil between piles, this article analysis and summary the sliding instabilitymechanism of the soil between piles, and ultimately determine the position and spacecharacteristic of the sliding surface. This article use the strength reduction method tocalculate the stability coefficient of soil between piles, and the combined with thedevelopment situation of localized shear band and characteristic of the sliding surface,synthetically analysis the stability of soil between piles.3）Based on the principle of single factor variable, this article has a discuss withthe cohesion, internal friction angle, airport surface width, air surface height andinterface strength total5factors. Respectively analyzed the three aspects influence forthe development situation of localized shear band, the position and space distributionfeature of sliding surface, the security coefficient with each factor, and analyzed thesensitively for each factor.