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Study On The Engineering Properties Of Driven Cast-in-place Tubular Piles

Posted on:2004-12-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:J N YeFull Text:PDF
GTID:1102360095455198Subject:Geotechnical engineering
Abstract/Summary:PDF Full Text Request
With rapid development of the engineering construction, it is urgent for the field of geotechnical engineering to develop a new type of pile with convenient construction process, reliable construction quality, high bearing capacity, great economical efficiency and enhanced foundation stability in the soft soil area. As far as deficiencies of driven cast-in-place pile and drilling cast-in-place pile are concerned, Xie Qingdao has successfully developed driven cast-in-place tubular pile (DCTP). As a new type of pile, DCTP is of good application prospects. However at present, the theoretical studies on the DCTP have not been reported, which has limited its popularization and application, so DCTP are fully studied in this paper.hi the paper, DCTP is introduced firstly, and current research status about pile theory is generalized and analyzed. Then the paper introduces testing results about DCTP reinforced soft foundation at the bridge-head of second-stage construction of Hang-Ning Highway. After the force and deformation rules of the DCTP reinforced soft foundation are analyzed fully, DCTP, plastic drain method and power deep mixing method used for reinforcement of the soft foundation are compared from the point of view of technologies and economical efficiency.Based on the consideration of soil core in pile, basic differential equations are respectively established for soil core and pile body using load transfer method, and semi-analytic solutions for DCTP settlement are obtained. Through analysis of an engineering example, major factors influencing engineering properties of DCTP are primarily explored.Using the finite element method (FEM) program, major factors influencing engineering properties of DCTP, stress and strain field of the soil core, and variable laws for load contribution ratio of inner friction resistance are analyzed. In the paper, stress coefficient (η) at the end of soil core is defined. Under the different pile strength, variable laws of η - Es and η - Eb/Es are studied, and empirical value of η is given. To be convenient for engineering application, a simplifiedcalculation method for bearing capacity of single DCTP is also put forward.To cover the deficiencies of field tests, bearing capacity, stress field and displacement field of soil at the end of DCTP and common cast-in-place pile are compared using the FEM program.Analysis results for two engineering examples show that there exist good compatibility between calculation results and testing results and it is feasible to use FEM to analyze the working properties of DCTP.
Keywords/Search Tags:cast-in-place tubular pile, load transfer method, semi-analytic solution, finite element method, bearing capacity, deformation mechanism, field test
PDF Full Text Request
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