隧道围岩-喷射混凝土界面应力解析

根据喷射混凝土支护隧道围岩的界面力学特点，考虑喷层与围岩结合界面受力和变形协调关系，并结合围岩承载拱效应，建立了围岩一喷层结构的复合曲梁共同承载模型，然后通过各微单元静力平衡推导复合曲梁的径向位移的控制微分方程，得到任意分布荷载作用下喷层与围岩界面应力以及喷层与围岩各自内力的解析式，可迅速获取喷层与围岩结合界面的力学状况，进而判断围岩稳定性与预测安全性，为隧道施工决策提供技术支撑。最后经隧道台阶法开挖的算例研究表明，喷层支护通过其与围岩的结合界面上传递应力使围岩内部形成压应力带，有利于围岩的稳定。

Analysis on Interfacial Stress Between Surrounding Rock and Shotcrete Lining

According to the characteristics of interracial stress between surrounding rock and shotcrete support, mechanical model of composite curved beame for support system of tunnel surrounding rock and shotcrete lining was established, considering the interracial deformation coordination and the effects of bearing arch of surrounding rock. Then from static equilibrium of two differential elements, the differential equations for the radial displacement of composite curved beam were obtained. All analytic formulas of both interracial stress and internal forces between surrounding rock and shotcrete lining by arbitrary distribution load were derived. And thus the mechanical condition of interface zone and the stress concentration position were obtained, which is convenient to assess the stability of surrounding rock and predict the safety. Finally, the analysis of tunnel project excavated by bench method showed that shotcrete lining made the formation of compressive stress zone in surrounding rock by transferring stress from the interface between surrounding rock and shotcrete, which is beneficial to improve the stability of surrounding rock.