隧道爆破作用下堆积层边坡稳定性的耦合数值分析  

Coupled Numerical Analysis of Slope Stability of Stacked Layer under Tunnel Blasting

作　　者：黄锋[1,2] 李硕 李思远 杨永浩 董广法 张庆明 HUANG Feng;LI Shuo;LI Si-yuan;YANG Yong-hao;DONG Guang-fa;ZHANG Qing-ming(State Key Laboratory of Mountain Bridge and Tunnel Engineering,Chongqing Jiaotong University,Chongqing 400074,China;School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China;Chongqing Communications Construction(Group)Company Limited,Chongqing 401122,China)

机构地区：[1]重庆交通大学省部共建山区桥梁及隧道工程国家重点实验室,重庆400074 [2]重庆交通大学土木工程学院,重庆400074 [3]重庆交通建设(集团)有限责任公司,重庆401122

出　　处：《科学技术与工程》2024年第26期11111-11120,共10页Science Technology and Engineering

基　　金：国家自然科学基金面上项目(52078090);重庆市自然科学基金面上项目(cstc2020jcyj-msxmX0679);山区桥梁及隧道工程国家重点实验室开放基金(SKLBT-19-006,SKLBT-YF2106)。

摘　　要：隧道施工爆破荷载会对地表边坡产生较大的动力扰动,加上堆积层边坡自身稳定性较差,极易形成堆积层滑坡、隧道塌方等工程事故。以渝湘高速樵坪山隧道工程为背景,结合CT扫描技术和PFC中clump命令,建立土石混合体颗粒流堆积层边坡数值模型并开展动三轴试验对堆积体模型的力学参数进行标定,运用FLAC^(3D)-PFC^(3D)耦合分析方法研究隧道开挖爆破作用下不同堆积层厚度边坡的稳定性。结果表明,在爆炸应力波的作用下,随着堆积层厚度从0.25倍隧道跨径增加至1.0倍时,堆积层颗粒速度减少4倍左右且颗粒松动范围几乎消失,颗粒沉降量从2 cm缓慢降至1 cm后保持稳定,颗粒间粘结与张拉力链比值从2.2迅速增加至4.5,此后颗粒间的张拉破坏作用较小,颗粒间不易发生滑移,堆积层稳定性较好;在超过1.0倍隧道跨径后,爆破产生的塑性区面积基本呈对称分布,且接近于隧道横断面面积,塑性区位于基岩范围内且集中在拱顶和拱底附近;总体上,当堆积层厚度超过1.0倍隧道跨径后,可显著降低隧道开挖爆破对边坡的动力扰动影响,研究结果可为隧道洞口段的设计与施工提供理论依据。The blasting load during tunnel construction generates significant dynamic disturbances to the surface slopes.The poor stability of the accumulated layer slopes makes it highly susceptible to forming landslides in the accumulated layer and causing tunnel collapses.Based on the Qiaoping Mountain Tunnel project on the Yu-Xiang Expressway,a numerical model of the soil-rock mixture granular flow accumulated layer slope was established by combining CT scanning technology and the clump command in PFC.Dynamic triaxial tests were conducted to calibrate the mechanical parameters of the accumulated layer model.The FLAC~(3D)-PFC~(3D) coupling analysis method was used to study the stability of slopes with different accumulated layer thicknesses under tunnel excavation blasting.The results show that under the action of explosive stress waves,as the thickness of the accumulated layer increases from 0.25 times to 1.0 times the tunnel span,the particle velocity in the accumulated layer decreases by about four times,and the range of particle loosening almost disappears.The particle settlement slowly decreases from 2 cm to 1 cm and then remains stable.The bond-to-tension force chain ratio between particles rapidly increases from 2.2 to 4.5.Subsequently,the tensile failure between particles is minimal,and particle sliding is less likely to occur,leading to improved stability of the accumulated layer.When the accumulated layer thickness exceeds 1.0 times the tunnel span,the area of the plastic zone produced by blasting is almost symmetrically distributed and approximates the cross-sectional area of the tunnel.The plastic zone is located within the bedrock range and is concentrated near the arch crown and arch base.Overall,when the accumulated layer thickness exceeds 1.0 times the tunnel span,the dynamic disturbance effect of tunnel excavation blasting on the slope is significantly reduced.These findings provide theoretical support for the design and construction of tunnel entrance sections.

关 键 词：隧道工程 爆破荷载 连续-非连续耦合 堆积层边坡 动力稳定性 

分 类 号：P642[天文地球—工程地质学]