摘要
为研究旋喷桩加固基底的浅埋大断面黄土隧道结构受力变形特征及基底加固时机的选择,采用室内模型试验与数值模拟相结合的方法,分析了基底加桩及不同加桩时机对隧道结构受力变形特征的影响。结果表明:旋喷桩加固基底效果显著,可有效降低隧底的围岩变形;方案一条件下的围岩应力释放较为充分,围岩变形量较大,实际施工中初支易侵限,隧底桩体全部处于受压状态,利于后期发挥桩体的有效承载力,在可保证隧道围岩稳定时建议选用;方案二较早的实现支护体系的"封闭",利于隧道结构的稳定,但隧底中部桩体处于受拉状态,在施工期易出现拉断现象,建议在隧道围岩条件差时选用,同时应对桩体进行加筋等类似措施处理。研究成果可为黄土隧道基底进行旋喷桩加固的时机选择提供借鉴。
In order to study the structural deformation characteristics of shallow-buried large-cross-section loess tunnels strengthened by jet grouting piles and the choice of time for foundation reinforcement,indoor model tests and numerical simulations were performed,and the influence of piles and application time on the mechanical deformation characteristics of the tunnel structure was analyzed.The results show that the reinforcement effect of jet grouting piles to the foundation is remarkable and the deformation of surrounding rock at the bottom of the tunnel can be effectively reduced.In the case of full cross-section reinforcement by piles,the stress release of the surrounding rock is relatively sufficient with a large deformation.The displacement of the initial support easily exceeds the limit range in actual construction,and all the piles at the bottom of the tunnel are under pressure,which is beneficial to mobilize the effective bearing capacity of the piles in the later period.It is recommended that the full cross-section reinforcement scheme is adopted while the surrounding rock of the tunnel is stable.In the case of pile reinforcement in stages,however,the earlier closure of the support system is beneficial to the stability of the tunnel structure,but the piles in the middle of the bottom of the tunnel are in tension state and hence,are easy to break during the construction period.It is suggested that the second scheme can be used when the surrounding rock of the tunnel is unstable and at the same time,the piles should be reinforced.The research can provide a reference for the choice of time reinforcement of rotary jet grouting piles for loess tunnel base.
作者
李又云
谢柯
孙永梅
李松皓
安鑫厚
LI Youyun;XIE Ke;SUN Yongmei;LI Songhao;AN Xinhou(Key Laboratory for Special Area Highway Engineerings Ministry of Education,Chang'an University Xi'an,Shaanxi 710064,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2019年第11期2332-2343,共12页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(51378004)
交通部西部建设项目(2014–318–J24–210)
陕西省自然科学基金资助项目(2130–2116–0351)~~
关键词
隧道工程
黄土隧道
旋喷桩
加固时机
模型试验
数值模拟
tunnelling engineering
loess tunnel
jet grouting pile
strengthening time
model test
numerical simulation
