穿越溶洞桥梁桩基嵌岩深度计算方法研究  

Methods to Calculate Rock-Embedded Depth of Bridge PileFoundation Passing Through Karst Caves

作　　者：陈慧芸 冯忠居[2] 谢富贵[3] 赵瑞欣 蔡杰 CHEN Huiyun;FENG Zhongju;XIE Fugui;ZHAO Ruixin;CAI Jie(School of Architecture and Civil Engineering,Xihua University,Chengdu 610039,China;School of Highway,Chang′an University,Xi′an 710064,China;Chengdu Tianfu Greenway Construction Investment Group Co.,Ltd.,Chengdu 610041,China;Fujian Transportation Construction Quality and Safety Center,Fuzhou 350001,China)

机构地区：[1]西华大学建筑与土木工程学院,四川成都610039 [2]长安大学公路学院,陕西西安710064 [3]成都天府绿道建设投资集团有限公司,四川成都610041 [4]福建省交通建设质量安全中心,福建福州350001

出　　处：《桥梁建设》2024年第3期109-116,共8页Bridge Construction

基　　金：国家重点研发计划项目(2018YFC1504801-04);福建省交通运输科技项目(201807)~~。

摘　　要：为准确计算岩溶区桥梁桩基嵌岩深度,依托莆炎高速公路岩溶区桥梁桩基工程,分别考虑桩基竖向极限承载力、桩身稳定性和桥梁全寿命周期内溶洞溶蚀量,提出3种穿越溶洞桥梁桩基嵌岩深度计算方法,并验证3种方法的可靠性。选取34根代表性桩基对比嵌岩深度设计值与所提方法计算值,并选取1根试桩对比规范值与所提方法计算值。结果表明:34根代表性桩基中,1根桩基的嵌岩深度设计值小于考虑全寿命周期内溶洞溶蚀量的嵌岩深度计算值,占比2.9%;10根桩基的嵌岩深度设计值同时满足竖向极限承载力、桩身稳定性和桥梁全寿命周期内溶洞溶蚀量要求,且安全储备合理,占比29.5%;23根桩基存在安全储备较高问题,占比67.6%,其中14.7%的桩基嵌岩深度设计安全储备高达5倍。各规范关于桩基嵌岩深度的取值差异较大,为确保桥梁桩基承载安全,同时降低施工难度和成本,建议设计穿越溶洞桥梁桩基的合理嵌岩深度时,充分考虑桥梁全寿命周期内溶洞溶蚀量。This paper presents three methods that can accurately calculate the rock-embedded depth of pile foundation in a karst zone,which consider the effects of vertical ultimate load bearing capacities of the piles,stability of the piles and cave dissolution amount in the bridge life cycle.The pile foundation of the bridge carrying a section of the Putian-Yanling Expressway in the karst zone is used as a case.34 representative piles were selected to verify the reliability of the three methods.The design rock-embedded depths of these piles were compared with the calculated depths,and a trial pile was selected to perform comparison of rock-embedded depth given in the specifications and depths calculated by the three methods.As per the analysis,the rock-embedded depth of one pile is smaller than the calculated rock-embedded depth considering the cave dissolution amount in the bridge life cycle,accounting for 2.9%.The design rock-embedded depths of 10 piles meet the requirements of vertical load bearing capacity of piles,stability of piles and cave dissolution amount in the bridge life cycle,with rational safety margin,accounting for 29.5%.The safety margins of 23 piles are large,accounting for 67.6%,among which,14.7%of the piles own safety margin five times larger than the design data.There exist great differences among the suggested rock embedded depths of pile foundations in different codes.To ensure the load bearing safety of pile foundation and reduce the construction complexity and costs,it is recommended to sufficiently consider the cave dissolution amount in the bridge life cycle,when calculating the effective rock-embedded depths of piles passing through karst zones.

关 键 词：桩基 岩溶区 嵌岩深度 竖向极限承载力 桩身稳定性 溶洞溶蚀量 计算方法 

分 类 号：U443.15[建筑科学—桥梁与隧道工程]