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针对原有三维膨胀本构模型的局限性,以富水泥质板岩隧道围岩的膨胀问题为出发点,采用侧向约束下的膨胀特性试验,修正了泥质板岩侧向约束下的轴向膨胀率与吸水时间的关系及膨胀过程中的一维本构关系;基于金尼克条件,考虑整个膨胀过程以及最大和最小膨胀应力对膨胀本构方程的贡献,以最大体积膨胀率对应的时间为临界时间,分段描述泥质板岩基于时间效应的三维膨胀本构模型。研究结果表明:泥质板岩在膨胀过程中轴向应力和膨胀率之间呈负对数函数关系;当吸水时间小于或等于临界时间时,侧向约束下的轴向膨胀率与吸水时间之间的关系式服从指数函数,体积膨胀率服从含时间效应的三维膨胀本构模型;当吸水时间大于临界时间时,侧向约束下的轴向膨胀率不再随时间变化,等于侧向约束下的最终轴向膨胀率,且体积膨胀率不再服从本构模型,等于定值(最大体积膨胀率)。研究成果可为解决富水软岩隧道围岩的膨胀问题提供理论参考。
Aiming at the limitation of the original three-dimensional expansion constitutive model, taking the expansion of surrounding rock in the cement-rich slate tunnel as the starting point, the expansion characteristic test under the lateral restraint was adopted to correct the axial constraint The relationship between the expansion rate and the water absorption time and the one-dimensional constitutive relationship in the expansion process. Based on the Kinnic condition, considering the contribution of the entire expansion process and the maximum and minimum expansion stresses to the constitutive equation of expansion, the maximum volume expansion corresponding to the time Critical time, section describes the three-dimensional swelling constitutive model of shale slab based on time effect. The results show that there is a negative logarithmic relationship between the axial stress and the expansion rate of shale slate during the expansion process. When the water absorption time is less than or equal to the critical time, the axial expansion rate and water absorption time The relationship between the two functions follows an exponential function, and the volume expansion rate obeys the three-dimensional expansion constitutive model with time effect. When the water absorption time is greater than the critical time, the axial expansion rate under lateral restraint no longer changes with time, equal to the lateral restraint Of the final axial expansion rate, and the volume expansion rate no longer follow the constitutive model, equal to the fixed value (maximum volume expansion rate). The research results can provide a theoretical reference for solving the expansion problem of the surrounding rock of water-rich soft rock tunnel.