水泥加固粉煤灰围岩三轴蠕变试验研究  

Triaxial Creep Study of Cement-Reinforced Fly Ash in Tunnel Surrounding Rock

作　　者：于亚军 余江波 杨尚川 YU Yajun;YU Jiangbo;YANG Shangchuan(Sichuan Road&Bridge Co.Ltd.,Highway Three Branch,Chengdu 610200,China;Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]四川公路桥梁建设集团有限公司公路三分公司,成都610200 [2]西南交通大学交通隧道教育部重点实验室,成都610031

出　　处：《河南科学》2024年第1期48-54,共7页Henan Science

基　　金：国家自然科学基金项目(52278371)。

摘　　要：隧道围岩的蠕变变形关系着其长期安全运营.为保证隧道围岩开挖后的蠕变稳定性,开挖前需使用水泥搅拌桩对粉煤灰软弱地层进行超前加固处理.但目前有关粉煤灰水泥土蠕变特性的研究较为缺乏.采用FLAC3D模拟隧道开挖得到围岩应力状态,基于此对加固后的粉煤灰水泥土围岩,进行室内三轴蠕变试验以研究围岩的蠕变特性.试验结果表明:偏应力载荷作用下,水泥加固后试样与重塑试样蠕变过程具有明显的差异性,加固后试样稳定蠕变阶段速率小于重塑试样,且加固后试样蠕变应变较小,最大可降低96.6%;此外,当偏应力超过试样的长期强度时,重塑试样提前进入蠕变加速阶段,而隧道围岩在经过水泥加固后,隧道各位置围岩的蠕变量同比减小70.2%以上.隧道围岩所受荷载与其长期强度之间的大小关系,决定了围岩的蠕变状态.Creep behavior in surrounding rock is vital for tunnel long-term stability.To ensure post-excavation creep stability,soft fly ash layers should be reinforced with cement-mix piles before tunnel excavation.However,research on fly ash-cement soil creep characteristics is limited.This study performs indoor triaxial tests on reinforced fly ash-cement soil,simulating the stress state of the tunnel using FLAC3D excavation models.Test results reveal significant differences in the creep processes of cement-reinforced and remodeled specimens under varying stress conditions.Reinforced specimens exhibit a lower stable creep rate than reshaped specimens,with creep strain in reinforced specimens being notably smaller,and reducible by up to 96.6%.Additionally,remolded specimens enter accelerated creep when deviatoric stress surpasses their long-term strength.In contrast,rock at the edge of the tunnel,post-cement reinforcement,enters accelerated creep at the initial stage,with creep strain near the tunnel reduced by over 70.2%.The surrounding rock creep state is determined by the relationship between the tunnel load and the rock long-term strength.

关 键 词：隧道 蠕变 粉煤灰水泥土 三轴试验 应力路径 

分 类 号：U452.2[建筑科学—桥梁与隧道工程]