路基岩溶塌陷上方多层加筋垫层荷载分布性状的大比例模型实验研究

Experimental study of load distributing behavior of multi-layer geotextile reinforced embankment subjected to the underneath sinkhole in a Karst terrain

采用加筋垫层防治路基下部岩溶塌陷可降低工程造价、确保运营安全,其承载机理和设计方法仍有待系统研究。设计了1∶5的大比例室内模型试验,通过实测和分析塌陷过程中单层、3层与4层土工格栅加筋垫层所受荷载和变形量,分析路基荷载在各层加筋体中的分布规律及垫层变形特征,并以此获得荷载分担系数等关键设计参数。试验结果表明,多层加筋垫层中顶层加筋体承担了40%-54%的上部荷载,而底层加筋体仅承担16%;加筋层数越多,中间层加筋体所分担的荷载越大,且垫层发生的变形量越小;塌陷坑上方土体的土拱效应较为明显,中部土压力的下降幅度和端部增加幅度均比单层加筋体大;陷坑上方土工格栅变形分布呈抛物线关系,且变形量由上往下依次递减。在实测数据分析的基础上得到了多层加筋垫层各加筋层的荷载分担系数,供实际工程参考。

Reinforced geotextile used to prevent karst collapse can lower the cost and ensure the safety of operation. However,the bearing mechanism and design methods remain to be further studied. A 1 ∶ 5 indoor model is designed for a test,in which we analyze the load and deformation of the single,triple and quadruplelayered reinforced geotextile,the load distribution in each layer of the geotextile,as well as the deformation of each year,in order to obtain key design parameters including the load distribution coefficients. The test shows that in the multi-layered geotextile,the top reinforcement bears 40%-54% of the load above while the bottom reinforcement holds only 16%. The more layers of enforcement,the heavier load the middle enforcement shares and the less deformation of the geotextile suffers. The soil arch effect above the collapsing pit is more obvious,and less pressure decreases in the earth pressure in the middle and pressure increase at the end are shown in the single-layered reinforcement. Geogrid deformation above the collapsing pit appears mathematically parabolic with the horizontal deformation increases. The test and data analysis indicate that the load distribution coefficients of the multi-layered reinforced geotextile can provide reference for practical engineering.