大直径钻埋桩压浆设计参数数值仿真

Numerical simulation of injecting cement design parameters for the large diameter bored pile

文章利用MARC软件，建立了分析单桩的空间轴对称有限元模型；借助Visual Fortran平台，对其功能进行二次开发，研编了分析土体初始应力的子程序SUBROUTINE UINSTR和分析动态接触的子程序SUBROUTINE UFRIC。在此基础上系统分析了桩侧压浆体模量、厚度及桩端压浆体厚度对大直径钻埋桩承载性状的影响，分析表明：（1）大直径钻埋桩侧压浆体的模量对承载力没有明显影响；（2）桩侧压浆合理厚度为18～25cm；（3）通过桩侧、桩端压浆，桩长为10m、30m、50m的钻埋桩承载力分别提高至少约40％、20％、14％。最后通过与实测结果比较，证明模型合理。

By using the Marc program, the spatial axisymmetrical finite element model was established; and with the Visual - Fortran platform, the function of the large common finite element MARC program was secondly developed. Two subroutines were written including the SUBROUTINE UINSTR for soil initial stress analysis and the SUBROUTINE UFRIC for dynamic contact analysis. With the model, this paper analyses the modulus of the injecting cement and the influence of thickness on the bearing performance of a large diameter bored pile. The following results are obtained ： （ 1 ） the modulus of the injecting cement around the pile has no influence on the bearing performance of the pile; （2） the rational thinness of the injecting cement around the pile is 18 - 25 cm; （3）by injecting cement around and under the pile, the bearing performance of pile are improved by about 40%, 20% and 14%, when the corresponding length of the pile is 10 m, 30 m and 50 m. The simulation results agree with the actual data. The model is proved to be appropriate.