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采用多层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,其承载机制和设计方法仍有待深入研究。设计1∶5的大比例室内模型试验,通过实测塌陷过程中单层、三层及四层土工格栅加筋垫层应力–应变及变形量,分析路基中各层加筋体的变形特征,土拱效应与各层荷载分担比例,以及路基顶面沉降和底层加筋体挠度间的相关关系,结合测试成果,探讨多层加筋垫层设计中的关键问题及相关计算理论,试验结果与数据分析表明:采用多层加筋时,路基土拱拱脚将上移至顶层加筋体附近,出现“双层土拱效应”现象;多层加筋垫层中顶层加筋体所分担的荷载最大,而底层加筋体所承担的荷载较小,各层格栅荷载分布不均匀;路基顶面沉降变形与底层挠度间关系可采用不计入剪胀特性的方法简化计算;底层加筋体挠度控制路基表面的沉降发展,而顶层加筋体由于荷载分担比例较大,对承载力起控制作用。在试验成果基础上提出多层加筋垫层的设计流程,并进行工程实例分析,可供实际工程参考。
The use of multi-layer reinforced cushion to prevent karst collapse in the lower part of the subgrade can reduce the construction cost and ensure the operation safety. The bearing mechanism and design method of the multi-layer reinforced cushion are yet to be further studied. The large-scale indoor model test of 1: 5 is designed. By analyzing the stress-strain and deformation of single, three and four-layer geogrid reinforced bedding during the collapse process, Soil arching effect and load sharing ratio of each floor, as well as the subgrade settlement and the bottom of the reinforced body deflection between the correlation between the test results, to explore the design of multi-layer reinforced cushion design and the key issues related to calculation theory, test results and The data analysis shows that when the multi-layer reinforcement is adopted, the foot of the subgrade soil arch will be moved up to the vicinity of the top stiffened body, resulting in the phenomenon of “double soil arching effect”; the top stiffened body in the multi-layer stiffened cushion The load shared by the bottom reinforcement is smaller and the load distribution is not uniform among the layers. The relationship between the settlement and deformation of the subgrade can be simplified by excluding the dilatancy characteristics. The bottom layer Reinforced body deflection control subgrade surface settlement development, and the top of the reinforced body due to a larger proportion of load sharing, the bearing capacity plays a controlling role. On the basis of the experimental results, the design flow of multi-layer reinforced cushion was put forward, and the engineering example analysis was conducted, which can be used for practical engineering reference.