隧道围岩的复合结构特性及其荷载效应

 基于地层岩土体的结构性和工程扰动特点，建立复合隧道围岩结构模型，提出围岩结构稳定性及其荷载效应的计算方法，实现荷载结构模型与地层结构模型的耦合。隧道施工引起的应力释放伴随着应力的转移，通常是由围岩中的压力拱实现传递的，表现出围岩的渐进破坏特点，按其稳定性特点可将围岩分为浅层围岩和深层围岩；深层围岩破坏的不连续性和阶段性本质上是由其分组特性所致，而每一组围岩则呈现同步或几乎同步运动的特点，并且一组围岩的失稳随即在其外侧形成一组新的岩层结构，用以维持其外部围岩的稳定，表现为随时空转化的复合拱结构模式；每组深层围岩通常是由“结构层”和“荷载层”构成，其中分层厚度较大、强度和刚度相对较高的岩层作为结构层控制着整组围岩的稳定性，通常位于围岩组的内侧，而厚度较小、强度和刚度也较低的岩层则作为荷载层而作用在结构层上。揭示结构层的失稳机制并给出相应的判据；明确提出复合隧道围岩结构的荷载效应是由浅层围岩的给定荷载和深层围岩的形变荷载组成，给定荷载取决于浅层围岩范围和性质，而形变荷载组取决于对结构层控制位态和传力岩层的刚度条件。

Compound structural characteristics and load effect of tunnel surrounding rock

Based on the structure feature and behavior subject to disturbance，a structural model was established for complicated surrounding rock in tunnel engineering. The model specified the structure stability and calculation method of load effect，and realized the coupling of the load-structure model with the stratum-structure model. After excavation，the initial stress is released and the pressure is transferred，usually in a form of pressure arch. The failure of surrounding rock shows a progressive character. The concept of deep buried and shallow buried surrounding rock was put forward according to the stability. The different structure features among rock groups resulted in the discontinuous and phase-dependent character of the failure of deep buried surrounding rock. Surrounding rock in the same group move synchronously and its simultaneous failure gives rise to the outside rock formation to sustain the stability of the exterior rock，that is，a composite arch structure varied with time and space. Each deep buried rock group consists of structure layer and load layer. For rocks in the structure layer，they usually own larger thickness，strength and stiffness，so as to maintain the stability of the rocks in this group. In contrast，rocks with small thickness，strength and stiffness are classified as load layer，exerting on the structure layer. The instability mechanism of structure layer was revealed and the corresponding criterion was presented. The load effect of complicated surrounding rock in tunnel engineering is composed of the given pressure of shallow buried surrounding rock and deformation pressure of the deep buried surrounding rock. The former depends on the scope and character of the shallow buried surrounding rock and the latter depends on the controlled state and stiffness of theforce transfer layer.