路基岩溶塌陷上方多层加筋垫层加固机制及荷载分担系数研究

发布时间：2018-07-09 22:10

本文选题：多层土工加筋体 + 岩溶塌陷　；参考：《长沙理工大学》2015年硕士论文

【摘要】：岩溶区塌陷易对高速公路路基造成不利影响,采用多层土工格栅加筋形成加筋垫层进行防治具有显著优势,但目前设计计算理论远远落后于工程实践,极大阻碍了其发展和应用,有必要对其展开系统的理论和试验研究。为此,本文拟基于土性试验、加筋体拉拔试验、土筋界面试验等手段,实测各材料的计算参数及筋土界面本构关系;在可模拟工况塌陷的模型箱内进行模型试验,实测塌陷产生时各层加筋体的变形和应变值,在此基础上,分析各层土工格栅上的荷载分布模式及荷载传递规律;然后采用三维数值计算软件FLAC3D对试验结果进行验证计算,并对各影响因素进行敏感性分析。综合分析研究得到下面规律和结论,为实际工程中格栅加筋体设计提供依据。(1)数值模拟得出的规律和模型试验基本保持一致,验证了试验数据的可靠性,对土工格栅加筋体的设计及施工具有一定的指导意义。(2)数值模拟各种工况下各层格栅其变形规律和模型试验相同,格栅挠度曲线接近符合抛物线规律。(3)同等条件下,岩溶塌陷坑宽度越宽,格栅的挠度会越大。即同样规格的土工格栅对于岩溶塌陷坑宽度差异表现出不同的适应性,具体是在满足要求的最大格栅挠度前提下,潜在岩溶塌陷坑宽度越小,格栅的拉伸强度需求越低。(4)加筋层数达到一定值时,即本实验中加筋层数为四层时,单纯的增加加筋层数对于原有格栅受荷性能影响不大,我们可以寻求其它改变来改善格栅的受荷性能。本次数值模拟同时也表明了四层格栅加筋是最经济合理的。(5)塌陷坑上方格栅变形规律符合抛物线关系,且变形量由上往下依次递减,非底层土工格栅变形范围不完全与陷坑范围一致。总体来说,多层加筋垫层相对单层加筋可有效减小变形量。(6)相同格栅规格和格栅间距条件下潜在岩溶塌陷坑的宽度大小对各层格栅荷载分担系数影响不大。
[Abstract]:Collapse in karst area is easy to cause adverse effect on highway roadbed. It has obvious advantages to use multi-layer geogrid reinforcement to form reinforced cushion layer, but the design and calculation theory is far behind engineering practice at present. Its development and application are greatly hindered. It is necessary to carry out systematic theoretical and experimental research on it. Therefore, based on the soil test, the drawing test of reinforced body and the interface test of soil reinforcement, the calculation parameters and the constitutive relation of the interface of each material are measured, and the model test is carried out in the model box which can be collapsed under simulated working conditions. The deformation and strain values of each layer reinforced body are measured when the collapse occurs. On this basis, the load distribution mode and load transfer law on each layer geogrid are analyzed, and the test results are verified and calculated by using 3D numerical calculation software FLAC3D. Sensitivity analysis of various influencing factors was carried out. The following laws and conclusions are obtained from the comprehensive analysis and research, which provide the basis for the design of grid stiffened body in practical engineering. (1) the law obtained by numerical simulation is basically consistent with the model test, and the reliability of the test data is verified. It has certain guiding significance for the design and construction of geogrid reinforced body. (2) the deformation law of each layer grid is the same as the model test under various working conditions, and the deflection curve of the grid is close to the parabola law. (3) under the same conditions, the deformation law of the grid is the same as that of the model test. (3) under the same conditions, The wider the width of karst collapse pit, the bigger the deflection of grid. That is to say, the same size geogrid has different adaptability to the difference of karst collapse pit width, in particular, under the premise of satisfying the maximum grid deflection, the width of potential karst collapse pit is smaller. (4) when the number of stiffened layers reaches a certain value, that is, when the number of stiffened layers is four layers in this experiment, simply increasing the number of stiffened layers has little effect on the original grid load performance. We can look for other changes to improve the grid's load performance. The numerical simulation also shows that the four layer grid reinforcement is the most economical and reasonable. (5) the deformation law of the grid above the collapse pit accords with the parabola relation, and the deformation decreases from top to bottom. The deformation range of the non-bottom geogrid is not completely consistent with that of the pit. In general, multi-layer reinforced cushion can effectively reduce deformation relative to single-layer reinforcement. (6) the width of potential karst collapse pit has little effect on the load sharing coefficient of each layer under the same grid size and grid spacing.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.16

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