影响格栅加筋膨胀土拉拔试验的新因素分析

不少学者开展过土中加筋拉拔试验,受测试仪器所限,大多通过改变填土含水率、厚度(上覆法向压力)、类型(粗、细粒土)及拉拔速度等因素来研究对试验结果的影响,除考虑筋材类型(土工格栅、带、网或布)外,对筋土中另一重要影响因素—筋材的初始张拉状态少有研究。本文采用长沙理工大学自行研发的大型数控拉拔试验系统,发挥其尺寸大、双向气囊加载、消除侧壁摩擦等优势,开展膨胀土中格栅加筋拉拔试验,探究筋材尺寸、初始张拉状态、温度、界面残余强度及拉拔方式等新因素对测试值的影响。结果表明:格栅尺寸有一定影响,尤其宽度影响较大;对最大拉拔力而言,格栅应力释放的影响近8.8%;拉拔方式的影响约12.1%;温度的影响为15.9%;残余强度的影响占23.6%。研究结果可供加筋膨胀土工程设计参考。

Analysis on New Factors Affecting Geogrid Pullout Test in Expansive Soil

Many scholars have carried out the reinforced pullout test in soil.Limited by the testing instruments,most of them study the influence on the test results by changing the moisture content,thickness (overburden pressure),type (coarse and fine soil),pullout speed and other factors.In addition to the type of reinforcement (geogrid,belt,net or cloth),there is few research on the initial tension state of reinforcement,which is another important factor in reinforced soil.In this paper,the CS-LB01 large scale numerical control pullout test system developed by Changsha University of Science and Technology was used to carry out the expansive soil reinforcement pullout test with the advantages of large size,bidirectional airbag loading,eliminating side wall friction,etc.The effects of geogrid size,initial tension state,air temperature,interface residual strength,pullout method,etc on the measured values were investigated.The results show that the size of the geogrid has a certain effect,especially the width.For Maximum pullout force,the effect of the grid stress release is nearly 8.8%,and the effect of the pullout mode is about 12.1%,and the effect of the temperature is 15.9%,the effect of the residual strength is 23.6%.The research results can be used as reference for engineering design of reinforced expansive soil.