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在Terzaghi理论假定的基础上,考虑圆形隧道侧压力系数及洞身范围斜向滑裂面作用,根据极限平衡法建立圆形隧道竖向支护压力的一般表达式,适用于密实砂土及硬黏土地层。该式表明圆形隧道的竖向支护压力随侧压力或侧压力系数λ的增大而减小,当λ=1时可得最小支护压力。为求解竖向支护压力,提出圆形隧道侧压力系数λ的计算方法,建立支护压力与衬砌刚度、地层刚度等因素的定量关系,表明随衬砌厚度的减小或地层弹性抗力系数的增大,侧压力系数增大,而竖向支护压力减小。通过对比表明,本文方法计算值与极限分析上限法、既有试验结果较接近且偏于安全,不仅适用于浅埋隧道,也适用于深埋隧道,且本文方法比极限分析上限法显著简化。
Based on the assumption of Terzaghi theory, considering the lateral pressure coefficient of circular tunnel and the effect of oblique sliding surface in the range of borehole body, the general expression of vertical support pressure of circular tunnel is established according to the limit equilibrium method, which is suitable for compact sand and Hard clay formation. The formula shows that the vertical support pressure of circular tunnel decreases with the increase of lateral pressure or lateral pressure coefficient λ. When λ = 1, the minimum support pressure is obtained. In order to solve the pressure of vertical support, a method to calculate the pressure coefficient λ of circular tunnel is proposed, and the quantitative relationship between support pressure and lining stiffness and formation stiffness is established. It shows that with the decrease of lining thickness or the increase of elastic resistance coefficient of formation Large, lateral pressure coefficient increases, while the vertical support pressure decreases. The comparison shows that the calculated value of this method and the upper bound method of limit analysis are both close and safe to the existing ones, which is not only applicable to shallow tunnels but also to deep tunnels. Moreover, this method is significantly simplified than the upper bound method of limit analysis.