摘要
结合西安地层特点,依托5座在建洞桩法地铁车站实体工程,分析了不同基础型式的结构承载特性和最不利工况,选取地基承载力、水平抗剪切、抗倾覆、基底抗隆起、结构允许水平位移作为评价基础结构强度及刚度安全性的基本准则,构建了洞桩法基础结构的力学模型,推导了不同破坏模式下结构的安全系数计算公式,提出了适用于西安地区洞桩法基础结构选型理论体系中各项安全系数取值建议,给出了不同地层及埋深条件下单排长桩基础和柱下条形基础的适用范围。研究结果表明:西安地区洞桩法基础结构按地基承载力、水平抗剪切、抗倾覆、基底抗隆起及结构允许水平位移等基本准则计算时,安全系数应分别不小于1.2、1.3、1.3、1.6、1.4;洞桩法的中柱基础结构选型主要受地基竖向承载力准则的影响,采用相同柱跨型式时,柱下条形基础在砂土地层中的适用性优于其在粉质黏土-砂互层和粉质黏土地层中的适用性,而单排长桩基础可通过增加桩长等方式提高结构承载力,理论上在各类地层条件下的适用性均优于柱下条形基础;边桩基础结构需要采用复合准则综合分析其适用性,柱下条形基础结构的适用性受地层条件影响较大,在粉质黏土和粉质黏土-砂互层条件下结构抗倾覆安全性难以满足要求,而单排长桩基础在各项准则下主要受自身结构强度和刚度的影响,在各类地层中的适用埋深无明显差异;西安地区洞桩法地铁车站采用单排长桩基础型式的适用性较好,而柱下条形基础可通过扩大基础宽度等方式来满足结构安全性要求。
Based on the stratum characteristics in Xi'an,the structural bearing characteristics of different foundation types and the most unfavorable working conditions were analyzed,with the five metro stations under construction by the pile-beam-arch(PBA)method as the example.The foundation bearing capacity,horizontal shear resistance,anti-overturning capacity,anti-uplift of the foundation,and allowable horizontal displacement of the structure were selected as the basic criteria for evaluating the structural strength and stiffness safety of the foundation structure.The mechanical model of the foundation structure by PBA method was constructed,and the calculation formulas of the structural safety factors under different failure modes were deduced.Some suggestions on the safety factors values in the type selection theory system of the foundation structure by PBA method in Xi'an were put forward.The application scopes of single-row long pile foundation and strip foundation under the column in different strata and buried depths were given.Research results show that when the foundation structure by PBA method in Xi'an is calculated according to the basic criteria of foundation bearing capacity,horizontal shear resistance,anti-overturning capacity,anti-uplift of the foundation,and allowable horizontal displacement of the structure,the safety factors should be not less than 1.2,1.3,1.3,1.6,and 1.4,respectively.The structure selection of the middle column foundation by PBA method is mainly affected by the vertical bearing capacity criterion of the foundation.When the same column span type is adopted,the applicability of the strip foundation under the column in the sandy soil stratum is better than that in the silty clay-sand interbedded stratum and silty clay stratum.The structural bearing capacity of the single-row long pile foundation can be improved by increasing the pile length.Theoretically,the applicability of the single-row long pile foundation under various stratum conditions is better than that of the strip foundation u
作者
来弘鹏
马小杰
LAI Hong-peng;MA Xiao-jie(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;Guangzhou Metro Design and Research Institute Co.,Ltd.,Guangzhou 510010,Guangdong,China)
出处
《交通运输工程学报》
EI
CSCD
北大核心
2024年第2期125-136,共12页
Journal of Traffic and Transportation Engineering
基金
国家自然科学基金项目(51978064,51908051,52278391)。
关键词
地铁车站
洞桩法
基础结构选型
安全性评判准则
力学模型
结构安全系数
metro station
pile-beam-arch method
foundation structure selection
safety judgment criterion
mechanical model
structural safety factor
