嵌岩深度对下伏溶洞桥梁桩基承载特性影响分析  

Analysis of the Influence of Rock Embedding Depth on the Bearing Characteristics of Underlying Karst Cave Bridge Pile Foundations

作　　者：武进广 吴南 周宏伟 WU Jinguang;WU Nan;ZHOU Hongwei(China Railway Seventh Group Co.,Ltd.,Zhengzhou 450016,China;Southwest Jiaotong University,Chengdu 610031,China;China Railway Seventh Bureau Group Third Engineering Co.,Ltd.,Xi'an 710032,China)

机构地区：[1]中铁七局集团有限公司,郑州450016 [2]西南交通大学,成都610031 [3]中铁七局集团第三工程有限公司,西安710032

出　　处：《铁道勘察》2024年第2期104-109,共6页Railway Investigation and Surveying

摘　　要：桥梁桩基下伏溶洞嵌入深度对桩身下沉量、承载力大小及桩基长期稳定性具有重要影响,依托某岩溶区桥梁工程,通过MIDAS GTS建立溶洞-桩基数值分析模型,获取桩顶沉降、桩基极限承载力及溶洞周边岩体应力分布规律,开展岩溶区桩基施工桩基的嵌岩深度与下伏溶洞桩基承载特性分析。研究表明,下伏溶洞桩基嵌岩深度越大,嵌岩段提供的摩阻力越大,下伏溶洞桩基承载力越大;随嵌岩深度增加下伏溶洞桩基承载力衰减度逐渐减小,短桩相较于长桩更易受溶洞影响,嵌岩深度超过临界值4d后(d为桩径),衰减度稳定在5%左右,可将下伏溶洞桩基视为普通嵌岩桩进行计算。因此,合理增加桩基嵌岩深度,能有效减小溶洞周边岩体所受应力,同时能避免溶洞周边出现受拉区。The embedded depth of the underlying karst cave under the pile foundation has a significant impact on the settlement,bearing capacity,and long-term stability of the pile foundation.Therefore,based on the construction project of the underlying karst cave pile foundation in a certain karst area bridge project,a numerical analysis model of karst cave pile foundation was established through Midas GTS.Based on the numerical analysis,the settlement of the pile top,the ultimate bearing capacity of the pile foundation,and the distribution of stress in the surrounding rock mass of the karst cave were obtained.Analysis was conducted on the embedded depth of pile foundations in karst areas and the bearing characteristics of underlying karst cave pile foundations.Research shows that the deeper the embedded depth of the underlying karst cave pile foundation,the greater the frictional resistance provided by the embedded section,and the greater the bearing capacity of the underlying karst cave pile foundation.As the depth of rock embedment increases,the attenuation degree of the bearing capacity of the underlying karst cave pile foundation gradually decreases.Short piles are more susceptible to the influence of karst caves compared to long piles.After the depth of rock embedment exceeds the critical value for 4d,the attenuation degree stabilizes at around 5%.The underlying karst cave pile foundation can be considered as an ordinary karst cave pile for calculation.Reasonably increasing the depth of pile foundation embedded in rock can effectively reduce the stress on the surrounding rock mass of the karst cave.

关 键 词：公路桥 岩溶 桩基 承载特性 嵌岩深度 

分 类 号：U448.14[建筑科学—桥梁与隧道工程] TU473.1[交通运输工程—道路与铁道工程]