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将围岩的塑性应变软化特性引入到考虑应力释放的圆形隧道黏弹塑性解中,并且在围岩的软化和残余强度阶段考虑围岩的塑性体积膨胀特性,提出了考虑塑性软化以及塑性体积膨胀和围岩应力释放的圆形隧道弹塑性解。当软化系数k=∞、膨胀系数h=s时,该解转化为黏弹-脆塑性解;当k=0、h=s时,则转化为黏弹-理想塑性解,进一步令h=s=1,则转化为不考虑塑性体积膨胀的黏弹-理想塑性解。通过具体实例计算,分析了掌子面与研究断面间距x、围岩的软化系数k、膨胀系数h和s、支护结构等对围岩塑性区、破碎区半径和变形的影响。当开挖面与研究断面间距x在(0~4)D(D为隧道直径)范围内,随着时间增加塑性圈和破碎区迅速增大;超过4D,塑性区和破碎区半径增量逐渐变小,趋于稳定值;围岩中包含塑性区和破碎区时,二者半径的比值只取决于围岩的性质,与支护结构无关,但支护结构可以限制塑性区及破碎区的范围;考虑应变软化和塑性体积膨胀时,围岩径向位移和塑性区及破碎区半径均大于不考虑应变软化和塑性体积膨胀时的结果;软化系数k增大,围岩位移、塑性区和破碎区半径增加、塑性区半径和破碎区半径之间的比值变小。得到的结果对于隧道工程设计和施工具有一定的指导性和参考价值。
The plastic strain softening property of surrounding rock is introduced into the viscoelastic plastic solution of circular tunnel considering the stress release. The plastic volume expansion of surrounding rock is considered in the stage of softening and residual strength of surrounding rock. The plastic softening and plastic volume Elastic - plastic solution of circular tunnel with expansion and surrounding rock stress. The solution transforms into a viscoelastic-brittle plastic solution when the softening coefficient k = ∞ and the expansion coefficient h = s. When k = 0 and h = s, it transforms to viscoelastic-ideal plastic solution, further making h = s = 1, then transformed into a viscoelastic-ideal plastic solution that does not consider the plastic volume expansion. Based on the concrete example, the influence of the distance between the face and the research section, the softening coefficient k, the expansion coefficient h and s, the supporting structure and so on on the radius and deformation of the plastic zone and the crushing zone of the surrounding rock are analyzed. When the spacing x between the excavation face and the study section is within the range of (0 ~ 4) D (D is the diameter of the tunnel), the plastic circle and the crushing zone increase rapidly with time increasing; Becomes smaller and tends to a stable value. When the surrounding rock contains plastic zone and crushing zone, the ratio of the two radii only depends on the nature of the surrounding rock and has nothing to do with the support structure, but the support structure can limit the plastic zone and the crushing zone The radial displacements of the surrounding rock and the radius of the plastic zone and the crushing zone are larger than those without considering the strain softening and the plastic volume expansion. When the softening coefficient k increases, the displacement of surrounding rock and the plastic zone and The radius of the crushing zone increases, and the ratio between the radius of the plastic zone and the radius of the crushing zone becomes smaller. The results obtained for the tunnel project design and construction has some guidance and reference value.