封闭作用对双层地基临塑荷载的影响  

Critical edge pressure analysis of two-layered ground considering closure effect

作　　者：问延煦[1] 周健[2] 

机构地区：[1]江苏省交通科学研究院,江苏南京211112 [2]同济大学地下建筑与工程系,上海200092

出　　处：《岩土工程学报》2008年第5期685-689,共5页Chinese Journal of Geotechnical Engineering

摘　　要：当硬壳层相对较薄而下卧软土处于流塑状态,硬壳层/荷载宽度的比值小于"地基基础规范02"的0.25下限值时,通过室内模型试验,测得软土层表层一点水平向土压力随荷载的变化规律。限于目前的实验条件,无法同时测得地基中一点的水平向应力和竖向应力,故无法透彻对封闭作用的力学本质进行分析。利用PFC程序建立了力学模型,分析了封闭作用下软土层中应力场的分布规律(弹性阶段),并以此为基础,结合应力路径的分析方法,从机理上阐明封闭作用对双层地基临塑荷载的影响。研究认为:由于硬壳层的封闭作用,软土层表层的K0值增加,推迟了软土层进入塑性阶段的荷载,从而提高了双层地基的临塑荷载。Model tests were carried out in laboratory to get the relationship between the vertical load and the horizontal soil pressure in the surface of soft mucky soil. The thickness of the crust overlying soft mucky soil was less than one fourth of the width of the loaded area. Being limited by the current experimental ability, the horizontal and vertical stresses of one point in ground couldn＇t be measured at once. It was the difficulty for the further analysis of the closure effect. PFC software was used to establish mechanical model for the analysis of stress distribution in soft soil during the elastic stage considering the closure effect. Based on the analysis of stress distribution in soft soil during the elastic stage, the stress path method was used to clarify how the critical edge pressure of the two-layered ground was affected by the closure effect. Then it was concluded that K0 in the surface of the soft mucky soil was increased due to the closure effect, so that the development of plastic state of the soft clay was delayed, and the critical edge load of two-layered ground was increased.

关 键 词：硬壳层 流塑状态 封闭作用 力学模型 临塑荷载 

分 类 号：TU470[建筑科学—结构工程]