刚性基础下复合地基褥垫层加筋影响研究  

Investigation of Influences of Geosynthetic Reinforcement on Composite Foundation Cushion Under Rigid Slab

作　　者：芮瑞[1] 谷金林 郑筱彦 陈成 翟玉新 孙义[1] RUI Rui;GU Jin-lin;ZHENG Xiao-yan;CHEN Cheng;ZHAI Yu-xin;SUN Yi(School of Civil Engineering and Architecture,Wuhan University of Technology,Wuhan 430070,Hubei,China;China Railway Construction Group Co.,Ltd.,Beijing 100040,China)

机构地区：[1]武汉理工大学土木工程与建筑学院,湖北武汉430070 [2]中铁建设集团有限公司,北京100040

出　　处：《建筑科学与工程学报》2022年第1期106-115,共10页Journal of Architecture and Civil Engineering

基　　金：国家自然科学基金项目(51208403,51708438);中铁建股份有限公司科技计划项目(218-C33)。

摘　　要：为了提高桩土荷载分担比,一些建筑工程桩筏基础下的复合地基采用了加筋垫层,然而加筋垫层复合地基的变形协调与荷载传递的影响还缺乏深入研究。采用自制的二维多活动门试验装置与椭圆钢棒相似土填料,开展了无筋褥垫层随桩间土下沉过程的模型试验,获得了不同垫层厚度下无筋垫层的变形与应力协调特性。在模型试验基础上,采用颗粒离散元DEM数值模拟建立了无筋与加筋垫层数值模型,揭示了有、无加筋条件下的褥垫层工作特性区别,并探讨了褥垫层厚度、桩间净距以及加筋位置等对褥垫层工作特性的影响。结果表明:当加筋高度距桩顶超过100 mm时,桩土应力比曲线和褥垫层变形均接近未加筋的情况;加筋体设置高度小于100 mm时,下方颗粒垫层的变形协调会受到影响,格栅与下部垫层之间产生脱空现象,从而导致桩土应力比随着桩间土下沉量的增加而出现陡升;陡升段起点对应的桩间土下沉量随着加筋位置的提高而增加,工程中可能会导致复合地基桩体超过承载力而引起复合地基发生破坏。To improve the pile-soil load transfer efficiency of composite foundation under rigid slab, geosynthetic-reinforced cushion is used under the pile raft foundation in some construction projects. However, the influences of geosynthetic reinforcement on the long-term deformation coordination and load transfer of composite foundation is still lack of in-depth studies. A series of model tests were carried out using a two-dimensional multi-trapdoor test device and elliptical steel rod analytical soil to study the working mechanism of unreinforced cushion of composite foundation. Deformation and stress coordination characteristics under different cushion thicknesses were revealed. Based on the model tests, particle flow discrete element method(DEM) was used to establish the numerical models of reinforced cushion and unreinforced cushion. The differences of working mechanism between reinforced cushion and unreinforced cushion was compared, and the influences of cushion thickness, clear distance between piles and geo-reinforcement height on the cushion working mechanism were discussed. The results show that the pile-soil stress ratios and the deformation are close to the unreinforced cushion when the reinforcement placement height is higher than 100 mm. The deformation coordination of the granular cushion will be affected when the reinforcement height is less than 100 mm, resulting in a rapid increase of pile-soil stress ratio with the increase of subsoil settlement. The starting point of steep rise section of the pile-soil stress ratio curve increase with the increase of reinforcement placement height, which could cause ground failure of piles of the composite foundation.

关 键 词：复合地基 褥垫层 土工加筋 刚性基础 活动门试验 离散元 

分 类 号：TU472[建筑科学—结构工程]