岩溶复杂发育区公路桥梁地基适宜性分析研究——以赤石特大桥为例  

Suitability analysis of highway bridge foundation in karst complex development areas——taking Chishi grand bridge as an example

作　　者：龚道平 胡惠华 王泗 夏立伟 方强 Gong Daoping;Hu Huihua;Wang Si;Xia Liwei;Fang Qiang(Hunan Provincial Communications Planning,Survey and Design Institute Co.,Ltd.,Changsha 410200,China)

机构地区：[1]湖南省交通规划勘察设计院有限公司,长沙410200

出　　处：《工程勘察》2024年第8期26-32,43,共8页Geotechnical Investigation & Surveying

基　　金：湖南省交通运输厅科技进步与创新计划项目(202120).

摘　　要：赤石特大桥是一座修建在岩溶复杂发育区的公路桥梁。大桥场地内由于构造作用与岩溶作用叠加,导致岩溶复杂发育,钻孔揭露最大发育深度超过100m。工程勘察采用钻探、物探相结合的勘察方法,揭示了场地内垂直岩溶与顺层面岩溶两种岩溶类型,查明了场地内岩溶发育的基本特征。从场地内的岩溶水文地质条件、岩溶充填物性状特征、桩基施工扰动影响等方面对场地岩溶地基的工程适宜性进行了详细分析和科学评价,提出了桥梁初始设计方案4×200m刚构桥的12号、13号主墩不适宜设置在岩溶发育深度大的溶塌角砾岩内这一重要地质问题,解决了桥梁结构需跨越的岩溶不稳定区域这一关键地质问题,并最终确定了主桥采用3×380m斜拉桥结构和4个主塔的安全位置。合理确定了5号主塔采用扩大基础,6号~8号主塔采用群桩基础,并评价了不同岩溶类型的桩侧摩阻力的确定原则。研究成果对岩溶复杂发育区的桥梁地基勘察具有借鉴价值。The Chishi grand bridge is a highway bridge built in a complex karst development area.The complex development of karst in the bridge site is due to the superposition of the tectonics and karst.The maximum development depth revealed by drilling exceeds 100m.The engineering survey adopts a combination of drilling and geophysical exploration methods,revealing two types of karst within the site:vertical karst and bedding karst and identifying the basic characteristics of karst development within the site.Based on karst hydrogeological conditions within the site and the characteristics of the karst filling material and the impact of pile foundation construction disturbance,the detailed analysis and scientific evaluation are conducted on the engineering suitability of the karst.It was proposed that the 12 and 13 main piers of the rigid frame bridge are not suitable for setting in karst collapse breccia with large development depth and the major geological problem of karst unstable areas that need to be crossed in bridge was solved.Finally the main bridge with 3×380m cable-stayed bridge structure and the 4 main tower positions were determined reasonably.The use of expanded foundation for the 5th main tower and the group pile foundation for the main towers from 6 to 8 were determined,and the determination principles of pile side friction resistance for different karst type were evaluated.The study results could provide the reference for the bridge foundation investigation in complex karst development areas.

关 键 词：赤石特大桥 岩溶复杂发育区 地基适宜性 岩溶稳定性评价 桩侧摩阻力 

分 类 号：TU45[建筑科学—岩土工程] U212[建筑科学—土工工程]