Research On Engineering Characteristics Of Double-row Piles Supporting Foundation Pit Slope And Its Influence Factors

At present, in the process of deep foundation pit excavation, how to guarantee the safety and stability of foundation pit and reduce the influence on the environment around the foundation pit such as building structures, municipal facilities and roads etc. is an important problem in foundation pit engineering, which puts forward strict requirements on the deep foundation pit supporting structure system. This paper took the foundation pit slope engineering of Longcheng international project in Chongqing wulong county as the research object, combined with the construction conditions, surrounding environment factors and hydrogeology situations of the project location, the supporting structure types of foundation pit slope were compared and double-row piles were determined the supporting system of foundation pit slope. Double-row piles supporting structure system has such advantages as large integral stiffness, small lateral deformation, no use of anchors or supports, small working face, fast speed and convenience of construction and so on. However, the forced mechanism of double- row piles is complex, there is no systematic calculation theory, the design basis is not perfect and mainly relies on engineering experience, therefore, the study of double-row piles supporting structure possesses of important theoretical and practical significances.Based on the analysis and conclusion of domestic and foreign double-row piles supporting structure research results, through the numerical simulation method, the supporting performance of double-row piles supporting structure and its influencing factors were studied by single factor analysis and orthogonal test analysis, in order to draw conclusions in favor of engineering practice. In this paper, the main work done is as follows:① The domestic and foreign research status of double-row piles supporting structure was surveyed, combined with the engineering own characteristics, the calculation model of foundation pit slope supported by double-row piles was determined.② The solid model of foundation pit slope was built by ANSYS finite element software and then imported into FLAC3 D finite difference software. The excavation by steps of the foundation pit slope supported by double-row piles structure was numerically simulated via FLAC3 D. According to the results of calculation, the foundation pit soil deformation and the stress and deformation characteristics of double-row piles supporting structure in the process of excavation were analyzed.③ The single factor analysis was carried on the effect factors of double-row piles supporting performance including pile diameter, pile spacing, row distance, built-in depth of pile body and section size of coupling beam. The influence of each factor on the deformation and stress distribution of double-row piles was studied.④ The orthogonal experiment analysis was conducted on the five factors of double-row piles and the sensitivities of double-row piles supporting structure to the factors were compared. The optimal parameters scheme was determined due to the analysis results, via the comparison of optimization plan and source plan, the validity of optimization plan was verified, thus providing references for the design of double-row piles supporting structure in actual engineering.⑤ On the basis of the above work, suggestions for the further research work were put forward.