The Analysis Of Geotextile Encased Stone Columns Composite Foundation Bear-deformation Mechanism

Gravel pile composite foundation as a common form of foundationreinforcement has been widely used in soft foundation reinforcement project. Thebearing capacity of gravel pile mainly depends on its radial confinement from thesoil to make gravel and other bulk materials are capable of forming the pile towithstand the vertical loads. During the engineering often due to soil around pile notproviding adequate lateral binding, gravel pile can easily happen lateral deformation,which lowers the bearing capacity of gravel pile foundation and significantlyincreases settlement and finally fails to get the expected reinforcement effect. Givensuch a pile of soil failure mode, geotextile is often used in parcel gravel pile under acertain depth below the surface of the gravel pile composite foundation with thetensile strength of geotextile can increase its radial confinement to limit lateraldeformation of the pile. and to avoid the premature ballooning damage, so as toimprove the bearing capacity of gravel pile composite foundation and reducecompression. The theoretical researches of this new type of reinforcement is laggingbehind, Therefore, this paper combining with the characteristics of geotextileencased stone columns composite foundation explores bear-deformation mechanismand studies its bearing capacity and settlement calculation methods.Firstly, Combined with the current domestic and international research scholars’geotextile encased stone columns composite foundation, and discussion bearing andground deformation mechanism. Based on elastic-plastic mechanics theory, thepaper analyzes the stress distribution of the load space of gravel pile, under themethod of Brauns, it combines the radical confinement provided by the geotextileand soil around pile, the self weight of the soil and column, and the friction on theinterface between the soil and column on the bearing capacity of the geotextileencased stone columns are considered. And the formula for calculating the ultimatebearing capacity of the geotextile encased stone columns is deduced with theultimate equilibrium method.Secondly, According to the bearing and deformation characteristics ofgeotextile encased stone columns composite foundation reinforcement area, The areacan be analyzed by the division of reinforced-hoop section and unreinforced-hoopsection, and corresponding computational models were established based on each segment of the force deformation characteristics. While the reinforced-hoop sectionuses displacement mode theory of piles of soil and establishes the vertical and radialdisplacement mode method of soil around the pile; the unreinforced-hoop section, onthe basis of pile-soil stress-strain relationship and the relative deformation of thepile-soil continuous and coordinated approach, solves the amount of compressiondeformation of each segment, Respectively and finally get the new settlementcalculation method for geotextile encased stone columns composite foundation.Finally, The reasonable and feasible of the geotextile encased stone columnscomposite foundation formula of single pile ultimate bearing capacity and settlementanalysis method can be verified by the engineering example, experimental results onthe field and the comparative analysis of the results of previous calculated methodand analysis methods in this paper. And the paper also makes parametric analysis forseveral factors and discusses its impact on the ultimate bearing capacity andsettlement.