城市复杂隧道群中超小净距夹岩稳定性研究

Stability of Interlaid Rock with Extra Small Clear Distance in Complex Urban Tunnel Group

以重庆红岩村处5座隧道组成的隧道群为背景工程,通过数值模拟和室内模型试验的方法,研究隧道群间夹岩的力学行为特征和破坏形态。结果表明:隧道群施工过程中,夹岩的主应力方向会发生偏转且应力集中效应明显,夹岩最薄弱处受剪严重且极易发生剪切破坏;夹岩最不利状态发生在第Ⅲ阶段(三纵线左侧主隧道开挖且未支护阶段);洞群失稳是从夹岩失稳开始的,故夹岩稳定是洞群稳定的关键,及时提供足够的支护反力或对夹岩加固才能够最大限度地保证夹岩的稳定性;模型试验得出的夹岩破坏过程和形式与实际工程中的相似、与理论分析和数值计算的基本吻合,验证了理论分析和数值计算的正确性。

The tunnel group with five tunnels in Hongyan village of Chongqing was taken as engineering background. The mechanical properties and failure modes of the interlaid rock in tunnel group were studied through numerical simulation and indoor model tests. The results indicated that during the construction of tunnel group, the direction of the principal stress of interlaid rock was deflected and the effect of stress concentration was significant. The weakest point of interlaid rock was subjected to shear where shear fail- ure occurred easily. The most unfavorable state occurred at the third stage （the left main tunnel of the third longitudinal expressway was excavated but not supported）. The instability of tunnel group initiated from interlaid rock. Therefore, the stability of interlaid rock is the key to the stability of the whole tunnel group. Only by providing sufficient supporting reaction or enhancing the strength of interlaid rock in time can the stability of interlaid rock be ensured to the greatest extent. The failure process and mode of inter- laid rock obtained from model test is similar to that of practical engineering, and agrees well with that of both theoretical analysis and numerical simulation, which has validated the correctness of theoretical analy- sis and numerical simulation.