摘要
针对高地应力软岩隧道中让压支护结构让压量小、协同性差等不足,基于合理释放围岩应力及协同变形机理,提出了具备两阶段让压功能的隧道分级让压支护结构。根据两阶段变形特点,基于荷载结构法,建立了分阶段力学简化计算模型,揭示了让压结构变形与围岩压力间的相互关系。此外,通过收敛约束法建立数值分析模型,对比强支护和让压支护时的围岩变形特点,揭示了让压支护结构应力分布规律。结果表明:让压点决定了结构进入让压阶段的时机,让压点过小将导致结构急速失稳,不满足围岩的早期变形控制要求,让压点过高则不利于结构让压变形的完全释放,延缓结构稳定时间,影响围岩稳定;增大让压量可显著释放围岩应力,降低结构受力,保障支护结构的稳定性。合理调控两阶段的让压量分担,可提高内拱架的稳定性,减小内拱架的应力集中,提高结构承载能力。所提出的分级让压支护结构通过两阶段让压达到提高让压量、释放围岩应力、减小结构受力的目的,保障了隧道围岩稳定,可为高地应力软岩环境下的支护措施提供借鉴。
Regarding the inadequacy of a small amount of let pressure and poor synergy in a soft-rock tunnel under high ground stress,based on the reasonable release of surrounding rock stress and synergistic deformation mechanism,a tunnel graded yielding support structure with a two-stage pressure release function is proposed herein.According to the characteristics of two-stage deformation,a simplified mechanical model was constructed in stages based on the load structure method to reveal the interrelationship between structural deformation and surrounding rock pressure.A numerical analysis model was established using the convergence constraint method to compare the deformation characteristics of the surrounding rock under the action of strong support and yielding support,and to reveal the stress distribution law of the support structure.The results show that the yield pressure point determines the time when the structure enters the yield pressure stage:too small a yield pressure point will lead to rapid destabilization of the structure,which does not meet the early deformation control requirements of the surrounding rock;too high a yield pressure point is not conducive to the complete release of the structure yield pressure deformation,which delays the stabilization time of the structure and affects the stability of the surrounding rock;increasing the let pressure amount can significantly release the surrounding rock stress,reduce the structural force,and ensure the stability of the support structure.Reasonable regulation of the two stages of pressure sharing can improve the stability of the inner arch,reduce the stress concentration in the inner arch,and improve the structural bearing capacity.The proposed graded pressure-let support structure can improve the pressure-let volume,release the surrounding rock stress,and reduce the structural stress through two stages of pressure let,which can guarantee the stability of the tunnel surrounding rock and provide a reference for the support measures in the high ground stress so
作者
董建华
徐斌
吴晓磊
DONG Jian-hua;XU Bin;WU Xiao-lei(Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province,Lanzhou University of Technology,Lanzhou 730050,Gansu,China;Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education,Lanzhou University of Technology,Lanzhou 730050,Gansu,China)
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2024年第3期342-355,共14页
China Journal of Highway and Transport
基金
国家自然科学基金项目(52178335)
中央引导地方科技发展资金项目(YDZX20216200001739)
陇原青年创新创业人才(团队)项目(2020RCXM120)
兰州市十大科技创新项目(2020-2-11)
甘肃省知识产权局高价值专利培育和转化项目(20ZSCQ034)
甘肃省基础研究创新群体项目(20JR10RA205)。
关键词
隧道工程
高地应力软岩
让压支护
力学分析
应力释放
tunnel engineering
high-stress soft rock
pressure support
mechanical analysis
stress release
