一种斜坡桥梁桩基础自由段桩长确定方法  

Calculation Method for Free Segment Length of Bridge Pile Foundation on Slope

作　　者：董捷 杨越 徐永明 宋绪国 DONG Jie;YANG Yue;XU Yongming;SONG Xuguo(School of Civil Engineering, Hebei University of Architecture, Zhangjiakou Hebei 075000, China;Geology and Subgrade Design Institute, China Railway Design Corporation, Tianjin 300142, China;National Engineering Laboratory for Digital Construction and Evaluation Technology of Urban Rail Transit,China Railway Design Corporation, Tianjin 300142, China)

机构地区：[1]河北建筑工程学院土木工程学院,河北张家口075000 [2]中国铁路设计集团有限公司地路院,天津300142 [3]中国铁路设计集团有限公司城市轨道交通数字化建设与测评技术国家工程实验室,天津300142

出　　处：《中国铁道科学》2018年第3期15-23,共9页China Railway Science

基　　金：国家科技支撑计划项目(2013BAG20B00);河北省自然科学基金资助项目(E2017404013);河北省教育厅重点科技开发项目(ZD2017224);河北建筑工程学院校科研基金资助项目(B_201604)

摘　　要：以斜坡桥梁桩基自由段桩长的确定方法为研究目标,将桩前自由段桩长范围内存在变形趋势的岩土体视为三维楔形受力体,考虑桩前受力体的自重及两侧拉力、受力体底部的极限抗滑力和摩阻力、桩土间接触压应力,推导其滑动力合力计算式,依据受力体的临界稳定状态确定斜坡桥梁桩基自由段桩长,并采用C#开发斜坡桥梁桩基自由段桩长的计算程序。运用该程序对斜坡桩基自由段桩长取值影响因素进行的敏感性分析结果表明:斜坡坡角、桩土接触压应力、内摩擦角对自由段桩长取值的影响较敏感,而桩周岩土体重度对自由段桩长取值的敏感性较小。采用此方法对长昆客运专线部分陡坡桥基自由段桩长设计取值的计算结果表明:当斜坡坡度较缓、地层较为坚硬时,位于其上的桥基内力计算可忽略自由段桩长的影响;当斜坡坡度较陡或斜坡岩土体强度较低时,计算得到的自由段桩长取值相对较大,斜坡桥梁桩基础设计须考虑自由段桩长对桩基内力计算的影响。Taking the method for determining the free segment length of bridge pile foundation on slope as the research target,the rock and soil mass with deformation trend in the free segment length of front pile is regarded as the three-dimensional wedge-shaped force body.Considering the dead weight of the force body in front of pile,the pulling force on both sides,the ultimate sliding resistance,frictional resistance at the bottom of the force body and the contact compressive stress between pile and soil,the formula for calculating its resultant sliding force is deduced.Based on the critical stability of the force body,the free segment length of bridge pile foundation on slope is determined,and the calculation program for the free segment length of bridge pile foundation on slope is developed by C#.The sensitivity analysis of the influencing factors on the free segment length of pile foundation on slope is carried out by using this program.Results show that the slope angle,the pile-soil contact compressive stress and the internal friction angle are relatively sensitive to the free segment length of pile,while the volume-weight of the rock and soil mass surrounding the pile is less sensitive to the free segment length of pile.The proposed method is used to calculate the design values of some free segment lengths of the steep slope bridge foundation on Chang-Kun passenger dedicated line.Results show that when the slope is gentle and the stratum is hard,the influence of the free segment length of pile can be neglected in the calculation of the internal force on bridge foundation.When the slope is steep or the strength of slope rock and soil is low,the calculated value of the free segment length of pile is relatively large.The influence of the free segment length of pile on the calculation of the internal force of pile foundation should be considered in the design of bridge pile foundation on steep slope.

关 键 词：斜坡 桥梁桩基础 楔形受力体 临界稳定状态 自由段桩长 

分 类 号：TU457[建筑科学—岩土工程]