摘要
岩溶路基随岩溶地区交通工程建设的快速发展而越来越普遍,如何评价岩溶路基稳定性成为岩溶区路基设计与施工的关键问题之一。针对目前路基岩溶顶板稳定性分析的不完善性,考虑溶洞形成过程中岩溶顶板所具有的空间形态特征,首先,将路基下伏岩溶顶板简化为固支梁、抛物线拱、圆拱与固支双向板等承载模型,以此进行路基岩溶顶板稳定性分析,并采用结构力学分析理论分别建立不同模型的路基岩溶顶板抗弯最小安全厚度计算方法;其次,通过典型案例的影响因素敏感性分析,揭示岩溶顶板最小安全厚度随溶洞顶板矢高、跨度、岩石抗拉强度与上覆荷载的变化规律,探讨路基岩溶顶板破坏模式的控制性因素及其影响规律,确定岩溶路基稳定性分析的基本原则;然后,基于岩溶地区地质勘察信息提出路基岩溶顶板稳定性分析过程,建立考虑溶洞空间形态特征的路基岩溶顶板稳定性分析方法;最后,通过工程实例计算分析验证所提方法确定的路基岩溶顶板稳定性评价结果的合理性与有效性。研究结果表明:岩溶顶板按何种模式破坏不仅与破坏形式有关,还与溶洞形态及其矢高密切相关,石灰岩抗拉强度同样影响较大,工程设计与稳定性评价时应基于勘测数据分析各种破坏模式,以便使设计或评价结果更接近实际情况。
Karst subgrades are being widely developed in conjunction with the rapid development of highway engineering construction in karst areas.Identifying methods to evaluate the stability of a karst roof in a subgrade is a major problem in subgrade design and construction in karst areas.Unfortunately,the current stability analysis methods of karst cavern roofs in subgrades possess many deficiencies.Based on the spatial form character of a karst cavern formed during the geological process,a karst cavern roof in a subgrade is first simplified in this study as one of the following types of models:clamped beam,parabolic arch,arch,two-way slab,or shell.The stability of a karst roof in a subgrade can then be analyzed using one of these models.Then,calculation methods of the minimum safe thickness of a karst cavern roof controlled by bending resistance are proposed based on structural mechanics.Second,changes in the minimum safe thickness of a karst cavern roof as well as different arch heights,spans,bending strengths of rock,and overburden are determined through a sensitivity analysis of the calculation results of a typical case.The controlling factors of the failure mode of a karst cavern roof and their effecting rules are also discussed,and the basic principles of stability analysis of a karst subgrade are presented.Third,the stability analysis process of a karst roof in a subgrade is suggested based on geologic exploration information of a karst area.The stability analysis method of a karst roof in a subgrade based on cavern spatial form can then be obtained.Finally,the reasonability of evaluation results of a karst roof in a subgrade and the effectiveness of the proposed method are verified by analyzing a single engineering case.The results show that the failure mode of a karst roof is not concerned with the destructional form but rather with the form,rise,and rock tensile strength of the karst cave.The project design and stability evaluation,which are completed based on the survey data,can yield results that approximate
作者
赵明华
袁腾方
张永杰
杨兴山
ZHAO Ming-hua;YUAN Teng-fang;ZHANG Yong-jie;YANG Xing-shan(Geotechnical Institute,Hunan University,Changsha 410082,Hunan,China;School of Civil Engineering and Architecture,Changsha University of Science&Technology,Changsha 410114,Hunan,China)
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2019年第11期109-117,共9页
China Journal of Highway and Transport
基金
国家自然科学基金项目(51278187)
关键词
道路工程
岩溶路基
空间形态
拱模型
破坏模式
安全厚度
road engineering
karst subgrade
spatial form
arch model
failure mode
safe thickness
