湿陷性黄土区公路涵洞地基处理措施效果研究

Research on the Effect of Ground Treatment Measures of Highway Culvert in Collapsible Loess Area

研究目的:湿陷性黄土地区公路涵洞病害时有发生,为解决湿陷性黄土地区公路涵洞因地基处理不当而导致的工后沉降变形过大等问题,本文以青海省新建民小一级公路沿线Ⅲ级自重湿陷性黄土地区的两座涵洞为工程实例,采用换填法和灰土挤密桩法分别对两座涵洞进行地基处理,对其处理效果和地基沉降变形特征进行研究,以期为不同地基处理方法在湿陷性黄土地区公路涵洞地基处理中的应用提供参考。研究结论:(1)换填法和灰土挤密桩法都能有效减弱或消除湿陷性黄土地区涵洞地基因浸水而引起的湿陷变形,可较大幅度地提高涵洞地基承载力;(2)灰土挤密桩法对提高地基土压缩模量比换填法更有效;(3)通过现场监测得到,换填法和灰土挤密桩法涵洞地基的一年累计沉降量分别为25.0 mm和18.2 mm,分别完成最终沉降量的79.9%和78.1%,两种复合地基的沉降变形呈现先增大后趋于平缓稳定的变化趋势;(4)经换填法和灰土挤密桩法处理过的涵洞地基累计沉降量都在稳定可控的范围内,能够有效提高涵洞结构的安全性,相比于换填法,灰土挤密桩法对降低湿陷性黄土压缩变形、提高地基承载力更为有效;(5)本研究成果可为湿陷性黄土地区涵洞地基设计和病害防治提供理论指导和科学依据。

Research purposes： The highway culvert diseases are often occurred in collapsible loess areas. In order to solve the problems of post - construction sedimentation and large deformation of eulverts caused by poor ground design in collapsible loess area, taking the two culverts of collapsible loess areas of Minhe to Xiaoxia I - grade highways in Qinghai province as examples, the actual effects of different ground treatment measures and settlement and deformation characteristics have been analyzed based on the methods of replacement and lime - loess compaction pile, to provide the reference for the application of different ground treatment methods of highway culvert in collapsible loess area. Research conclusions： （ 1 ） The methods of replacement and lime - loess compaction pile can effectively eliminate or decrease the collapsible deformation of culvert ground caused by soaking and improve the bearing capacity of culvert ground significantly. （2） Compared with the replacement method, the lime -loess compaction pile method is moreeffective in the aspect of improving the compression modulus of ground soil. （3） By the field monitoring dada, the accumulative total sedimentation during a whole year is 25.0 mm for the replacement method and 18.2 mm for the lime - loess compaction pile method, and accounts for 79.9% and 78. 1% of final settlement respectively. The settlement deformation of both kinds of composite ground presents the trend of the increasing rapid in the early stage and smooth and stable in the late. （4） The cumulative settlement of culverts which were processed by ground treatment keeps in a stable and controllable range, which can effectively improve the security of culvert structure. Lime - loess compaction pile method may perform a more important function in reducing the compression deformation of collapsible loess and improving the bearing capacity of culvert ground than the replacement method. （5） The research results can provide the theoretical guidance and scientific basis for ground design and disease prevention of culvert in collapsible loess areas.