穿越双层溶洞桩基极限承载力试验研究  

Experimental study on ultimate bearing capacity of pile foundation traversing double-layer karst caves

作　　者：雷勇[1] 赵子朝 李鹏甲 李金朝 LEI Yong;ZHAO Zizhao;LI Pengjia;LI Jinzhao(School of Civil Engineering,Hunan University of Science and Technology,Xiangtan 411201,China)

机构地区：[1]湖南科技大学土木工程学院,湖南湘潭411201

出　　处：《交通科学与工程》2025年第1期140-147,共8页Journal of Transport Science and Engineering

基　　金：国家自然科学基金项目(51878270、52178332);湖南省自然科学基金项目(2022JJ30253)。

摘　　要：【目的】解决岩溶区穿越多层溶洞桩基承载力的取值问题。【方法】依据相似原理开展了穿越不同高度双层溶洞桩基承载力的室内模型试验。【结果】通过分析桩基与溶洞顶板及隔板的破坏模式,得到桩身稳定系数的取值范围,并总结出桩基极限承载力的变化规律。【结论】1)桩基极限承载力随溶洞洞高的增加而逐渐减小,在达到6倍桩径的临界洞高时,桩身破坏模式由桩顶材料受压鼓胀破坏转变为桩身屈曲失稳破坏。2)溶洞顶板与隔板的破坏模式与两侧基岩约束类型及桩侧摩阻力的大小有关。两端固支条件下溶洞顶板、隔板整体破坏模式类似于集中荷载作用下的两端固支板受弯破坏。桩-岩接触处发生局部剪切、冲切组合破坏。3)在桩周岩土体不发生破坏的前提下,当溶洞洞高小于6倍桩径时,桩基发生桩顶材料受压鼓胀破坏,其极限承载力取决于桩基自身材料的强度;当溶洞洞高大于或等于6倍桩径时,上层溶洞段桩身发生屈曲失稳破坏,其极限承载力取决于桩身临空段的屈曲承载力。[Purposes]This paper aims to solve the value-taking problem of the bearing capacity of the pile foundation traversing through double-layer karst caves in karst areas.[Methods]An indoor model experiment on the bearing capacity of pile foundation traversing double-layer karst caves with different heights was carried out according to the similarity principle.[Findings]Through the analysis of the failure modes of the pile foundation and karst cave roof and partition,the value range of the pile stability coefficient was obtained,and the variation law of the ultimate bearing capacity of the pile foundation was summarized.[Conclusions]1)The ultimate bearing capacity of the pile foundation decreases with the increase in the karst cave height.When the critical karst cave height of 6d(d refers to the pile diameter)is reached,the failure mode of the pile body changes from the compression and swelling failure of the pile top material to the buckling instability failure of the pile body.2)The failure mode of the karst cave roof and partition is related to the constraint types of the bedrock on both sides and the size of the shaft frictional resistance.The overall failure mode of the karst cave roof and partition under the condition of fixed supports on both ends is similar to the bending failure of the fixed support plates at both ends under the concentrated load.A combined failure mode of local shear and punching shear occurs at the pile-rock contact position.3)Under the premise of no damage caused to the rock and soil around the pile,when the karst cave height is less than 6d,the pile top material is subjected to compression and swelling failure,and its ultimate bearing capacity depends on the strength of the pile foundation material.Nevertheless,when the karst cave height is equal to or greater than 6d,the upper karst cave section of the pile body undergoes buckling instability failure,and its ultimate bearing capacity depends on the buckling bearing capacity of the suspended section of the pile body.

关 键 词：地基基础工程 岩溶桩基 极限承载力 模型试验 破坏模式 

分 类 号：TU473.1[建筑科学—结构工程]