超载预压处理软土路基卸载时间的探讨  

Discussion of Soft Foundation Unloading Time Treated with Overload Precompaction

作　　者：杨烈[1] 

机构地区：[1]中铁二院西安勘察设计研究院有限责任公司,西安710054

出　　处：《高速铁路技术》2013年第3期54-57,共4页High Speed Railway Technology

摘　　要：超载预压是一种传统的、常用的软土路基处理方法。目前对超载预压处理软基卸载时间的计算常用以下3种方法:(1)工后沉降法是通过预测最终沉降值,以计算工后沉降小于容许值作为卸载时间。该法参数的选择是保守的,很多是经验系数,一般计算的预压时间偏长;(2)有效应力面积法是通过计算在路堤使用荷载作用下压缩土中总应力分布面积A与超载作用下有效应力分布面积B之比,根据比值判定卸载时间。该法概念明确,计算过程简便,经常作为对超载时间进行粗略估计时使用;(3)反演沉降系数法是利用实测沉降资料,用反分析法确定计算参数,较准确地预测超载预压地基的工后沉降,为地基卸载确定合理的时间。设计时可采用工后沉降法、有效面积法计算,施工后,得到实测沉降资料,再采用反演沉降系数法,合理地预测卸载时间。Overload precompaction is a traditional,common method for soft foundation treatment.Three methods are used nowadays for the calculation of soft foundation unloading time treated with overload precompaction:(1 )the settle-ment after construction method is adopted to predict the final settlement value,to calculate the settlement after construc-tion is less than the permissible value as the unloading time,the method of parameter choice is conservative,many em-pirical coefficient,the general calculation of preloading time lengthened;(2)the effective stress area method is by cal-culating in the embankment loads of compressibility of soil total stress distribution area of A and the overload of effective stress distribution area ratio of B,according to the ratio of determination of unloading time,this method is clear in con-cept and simple in calculation process,which is often used as a rough estimate of overload time and sedimentation coeffi-cient;(3 )inversion settlement coefficient method is based on the measured settlement data,calculation of parameters by using back analysis method,an accurate prediction of soft ground improved by overload precompaction settlement af-ter construction,determine the reasonable time for the foundation of unloading.Method of settlement after construction, the effective area method and calculation shall be adopted in design;after construction,settlement data is obtained,the inversion settlement coefficient method shall be used to forecast the unloading time reasonably.

关 键 词：超载预压 工后沉降 卸载时间 预测 固结 软土地基 

分 类 号：TU471.8[建筑科学—结构工程]