一种基于分区段模式土工加筋拉伸应变分析方法  

A tensile strain analysis approach for basal geosynthetic reinforcement based on different working section mode

作　　者：吕伟华[1,4] 刘维正 孙信[3] 张继周 LüWeihua;LIU Weizheng;SUN Xin;ZHANG Jizhou(School of Civil Engineering,Nanjing Forestry University,Nanjing 210037,China;School of Civil Engineering,Central South University,Changsha 410075,China;Jiangsu Communications Holding Co.,Ltd.,Nanjing 210016,China;Highway Geological Disaster Prevention and Control Engineering Technology Research Center,Yinchuan 750004,China)

机构地区：[1]南京林业大学土木工程学院,江苏南京210037 [2]中南大学土木工程学院,湖南长沙410075 [3]江苏交通控股有限公司,江苏南京210016 [4]公路地质灾害防治工程技术研究中心,宁夏银川750004

出　　处：《铁道科学与工程学报》2021年第5期1155-1167,共13页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51508279);江苏省自然科学基金资助项目(BK20150885);住建部科技计划资助项目(2018-K4-008)。

摘　　要：桩承式加筋路堤在软土地基道路工程中的应用越来越广泛,在对该复合体系中的水平土工加筋进行等效兜提作用的薄膜效应评价时,传统研究方法主要存在2点不足:一是在进行加筋体受力分析时对筋材的区段工作模式的区分还不够明确,这不利于定量刻画筋层的拉伸应变分布和大小及其受挠曲形态变化的影响;二是多数加筋拉应变分析方法以基于筋材净跨挠曲范围内的应变均值化为前提,容易错误估计其荷载调配作用而得不到合理的加筋拉应变峰值设计取值。为更好地评判水平加筋体的薄膜效应以便得到其合理的拉伸应变,开展以水袋泄水模拟路堤底局部沉降差的模型试验,进行路堤应力、位移与筋材拉应变等监测结果的变化规律分析,并基于水平铺设的土工加筋区分为锚固段、过渡段与挠曲段工作模式的拉应变非均匀分布特性,引入加筋体与填料的接触界面摩擦强度指标,推导了一种二维理想条件下路堤底通长布置的加筋体拉伸应变分析方法,且给出了简化的计算表达公式,并得到了实测数据的合理性验证。研究结果表明,所提方法可改进传统方法以拉应变为常数值假定的局限,并适当考虑土工加筋与填料界面接触相互作用,为相关的研究与工程应用提供参考。The geosynthetic-reinforced and pile-supported(GRPS)embankment technology has been widely adopted in road engineering on soft soil foundations.In the current design guidelines or those traditional geomembrane evaluation methods,distinction of working mode of the geosynthetic reinforcement in the mechanical performance analysis was not clearly interpreted.Determination of the tensile strain within the geosynthetic length is always founded upon a uniform hypothesis to fulfill the deflected membrane effect evaluation.Subsequently,influence of the geosynthetic deflection on the lateral tensile strain could not be appropriately estimated,which indicated that the pocket effect from geomembrane would be unreasonably evaluated in the geosynthetic design procedure.Therefore,a physical model test was conducted to evaluate the reinforcing performance by analyzing the earth pressures,displacements and tensile strains within a large-scale embankment model,in which the settlement of a rubber water bag was induced by setting water leakages at the fill base.In the theoretical analysis,the working mode condition of the reinforcement was assumed to consist of an anchorage section over the hard foundation soil,a transition section at the local sinking edge and a flexure section within the deflected zone.Comparing with other analytical methods,the proposed method considers the nature of nonuniform strain distribution and the interaction with soil arching effect.Moreover,the mechanical behavior of interface between reinforcement and up and down fill material can be partially considered,as well as the influence of friction strength indexes on its ultimate distribution and magnitude of tensile strains.At last,the present method is validated by monitored data from another field model test,and some useful conclusions can be obtained.This study can be referenced by relevant research and engineering application.

关 键 词：桩承加筋路堤 土工加筋 分区模式 拉应变 计算方法 

分 类 号：TU431[建筑科学—岩土工程]