上软下硬地层隧道开挖三维有限元分析.pdfVIP

D0I:10.13905/j.cnki.dwjz.2023.11.034

上软下硬地层隧道开挖三维有限元分析

THREEDIMENSIONALFINITEELEMENTANALYSISOFTUNNELEXCAVATIONINUPPERSOFT

ANDLOWERHARDSTRATA

解洋

（中电建铁路建设投资集团有限公司，北京100060）

XIEYang

(PowerchinaRailwayConstructionInvestmentGroupCo.,Ltd.,Beijing10060,China)

【摘要】上软下硬地层大断面隧道受力结构复杂，分步开挖对围岩扰动大、风险高。为分析大断面隧道开挖受力特性，探寻分

步开挖变形规律，利用MIDAS/GTSNX岩土分析软件建立三维有限元模型，对隧道开挖过程中地表沉降、隧道收敛、锚杆轴力、

初支应力受力特性进行研究。通过分析得出，上软下硬地层大断面隧道开挖地表沉降主要发生在上台阶施工阶段，上台阶开

挖引起的地表沉降占总体沉降量的97%；硬岩地层大断面开挖台阶间距对地表沉降、隧道收敛、初支结构受力影响不大。研究

成果可为上软下硬地层大断面隧道开挖提供借鉴和参考。

【关键词】上软下硬地层；大断面隧道；三维有限元模型

【中图分类号】TU473.2【文献标志码】A【文章编号】1001-6864(2023)11-0151-04

Abstract:Thestressstructureoflargecross-sectiontunnelsinuppersoftandlowerhardstrataiscomplex,and

step-by-stepexcavationhasahighdisturbanceandrisktothesurroundingrock.Inordertoanalyzethestresschar-

acteristicsoflarge-sectiontunnelexcavationandexplorethedeformationlawofstep-by-stepexcavation,a

three-dimensionalfiniteelementmodelwasestablishedusingMIDAS/GTSNXgeotechnicalanalysissoftwareto

studythestresscharacteristicsofsurfacesettlement,tunnelconvergence,anchoraxialforce,andinitialsupport

stressduringtunnelexcavation.Throughanalysis,itcanbeconcludedthatsurfacesettlementduringexcavationof

largecross-sectiontunnelsinuppersoftandlowerhardstratamainlyoccursduringtheconstructionstageoftheup-

perbench,withsurfacesettlementcausedbyexcavationoftheupperbenchaccountingfor97%ofthetotalsettle-

ment.Thespacingbetweenlargecross-sectionexcavationstepsinhardrockstratahaslittleeffectonsurfacesettle-

ment,tunnelconvergence,andinitialsupportstructurestress.Theresearchresultsmayprovidethereferenceforthe

excavationoflargecross-sectiontunnelsinuppersoftandlowerhardstrata.

Keywords:uppersoftandlowerhardstrata