基于虚拟嵌固点法的桩基稳定性数值分析  

Numerical analysis of the plies bucking stability based on illusion embedded solid point method

作　　者：贾强[1,2] 栾树[1,2] 张鑫[1,2] 

机构地区：[1]山东建筑大学土木工程学院,山东济南250013 [2]山东省建筑结构鉴定加固与改造重点实验室,山东济南250013

出　　处：《山东建筑大学学报》2017年第1期12-20,共9页Journal of Shandong Jianzhu University

基　　金：国家自然科学基金资助项目(51278286);教育部科研创新团队支持计划项目(IRT13075);山东省教育厅科技计划项目(J10LE06)

摘　　要：运用桩基托换支撑既有建筑物地下增层时,随着桩周土的开挖,桩的稳定性会降低。因此,开展在桩周土开挖条件下的桩基稳定性的研究尤其重要。针对虚拟嵌固点法缺少半嵌固状态桩基稳定性计算公式的问题,文章利用ANSYS程序建立二维有限元模型,分析了在桩周土开挖条件下的桩的稳定性,建立了基于虚拟嵌固点法的半嵌固状态桩的稳定性计算公式,并对其进行了验证。结果表明:随着桩入土深度的增加,桩的稳定性系数趋近一定值,符合虚拟嵌固点法的基本假定;在桩周土开挖深度不变的条件下,桩径越大、桩周土水平反力系数越大、桩外露长度越小、桩顶约束越强则桩的稳定性系数越大;在桩身长度不变的条件下,随着桩周土开挖深度的增加,桩的稳定性系数降低;提出的基于虚拟嵌固点法的半嵌固状态下稳定性计算公式,其计算结果和数值分析的结果平均误差率仅有8.1%,与规范公式相比更符合桩的实际受力状态。The underpinning pile can be used to support the existing building for construction of basement.The soil excavation around the pile can decrease the bearing capacity of piles.Therefore,it is especially important to study the stability of the plies bucking stability under the condition of pile soil excavation.For the lack of the formula of calculation length of compressed pile under the states that the part half-embedded pile depth in soil,ANSYS finite element analysis program was used to analyze the stability characteristics of pile under the excavation condition.A formula of calculation length of compressed pile is put forward under the states that the part of pile depth in soil is halfembedded,and the verification is carried out.The results show that,with the increase of pile depth in soil,the stability coefficient of pile reaches a certain value,which is so called critical value of depth in solid.This conclusion fits the assumption of illusion embedded solid point method.Under the same excavation depths condition,the pile has the higher value of stability coefficient in wider pile diameter,the higher level of soil reaction force coefficient,the shorter length of compressed pile or the stronger constraint on top of pile.Under the same pile lengthens condition,the bearing characteristics of pile decreases with the soil excavation.This paper puts forward the formula of calculation length of compressed pile under the states that the part of pile depth in soil is half-embedded.The formula of calculation length of compressed pile under the states that the part of pile depth in soil is halfembedded,which has only 8.1%difference with the numerical analysis results,fitting the actual load conditions.

关 键 词：虚拟嵌固点法 桩周土开挖 桩基稳定性 临界入土深度 数值分析 

分 类 号：TU430[建筑科学—岩土工程]