寒区隧道应力和位移弹塑性统一解及对比分析

Unified Elastoplastic Solution and Comparative Analysis of Stress and Displacement for Tunnels in Cold Regions

选择合理的屈服准则分析寒区隧道弹塑性解能为寒区隧道稳定性分析提供理论基础。为此,结合Mohr-Coulomb准则(即M-C准则)和外接圆Drucker-Prager准则(即D-P准则)分析得到考虑中间主应力效应的统一强度准则,建立寒区隧道弹塑性力学计算模型,基于线性非关联准则推导得出考虑围岩不均匀冻胀特性的寒区隧道应力场及位移场的弹塑性统一解,并对所得统一解答式进行算例及参数分析。研究表明:采用M-C准则计算偏于保守,而利用外接圆D-P准则计算偏于危险,考虑中间主应力效应能充分发挥围岩承载潜能,有效缩小塑性半径,缓解衬砌冻胀变形;统一强度理论参数b保持常数时,初始地应力、衬砌强度、不均匀冻胀系数及围岩体积冻胀率等参数的变化对寒区隧道应力及塑性半径变化影响显著。该研究成果可丰富寒区隧道工程设计理论。

The selection of a reasonable yield criterion to analyze the elastoplastic solution of tunnels in cold regions can provide a theoretical basis for the stability analysis of tunnels in cold regions.Thus,the unified strength criterion considering the coefficient of intermediate principal stress was obtained by combining Mohr-Coulomb criterion(M-C criterion)and Drucker-Prager criterion(D-P criterion)of circumscribed circle,and an elastoplastic mechanics calculation model for tunnels in cold regions was established.Based on the linear non correlation criterion,a unified elastoplastic solution of the stress field and displacement field for tunnels in cold regions was derived considering the non-uniform frost heave characteristics of surrounding rock,and the example and parameter analysis for the unified solution was conducted.The results show that calculation using the M-C criterion is conservative,while the calculation using the D-P criterion of circumscribed circle is dangerous.In addition,considering the effect of intermediate principal stress,the potential strength of surrounding rock can be fully utilized,which can effectively reduce the plastic zone radius and alleviate the frost heave deformation of the lining.When the parameter of unified strength theory b keeps constant,the changes of initial ground stress,lining strength,non-uniform frost heave coefficient and volume frost heave ratio of surrounding rock have significant effects on the changes of stress and plastic radius for tunnels in cold regions.The research results can enrich the design theory of tunnel engineering in cold regions.