高内水压作用下围岩-叠合式衬砌承载机理力学分析

Mechanical Analysis of Bearing Mechanism of Surrounding Rockand Multi-layer Lining under High Inner Hydraulic Pressure

为探究圆形水工隧洞衬砌结构中围岩-叠合式衬砌联合承载的力学机理,针对珠江三角洲水资源配置工程“外衬管片-自密实混凝土填充层(SCC)-内衬钢管”三层叠合的衬砌结构形式,采用平面弹性复变函数理论的幂级数解法,从应力函数层面着手,基于围岩-衬砌相互作用关系以及应力边界条件建立了相应的力学模型,推导求解了在开挖荷载和内水压共同作用下围岩和各层衬砌域内任意点的应力分量,揭示了叠合式衬砌结构承载时的荷载传递机理和规律。然后通过边界应力结果以及与数值结果的比对,验证了提出方法的正确性;最后通过参数分析,着重讨论了高内水压对输水隧洞围岩和三层衬砌径向正应力和环向正应力的影响。结果表明:围岩-衬砌联合承载时,围岩和三层衬砌的径向正应力和环向正应力结果均符合余弦分布,而剪应力符合正弦分布;随着输水隧洞内水压增加,三层衬砌和围岩在径向上更趋于压缩,而环向正应力趋向于拉应力并增大。研究成果可为该类型衬砌防护工程的设计和施工提供理论依据。

In the aim of exploring the mechanical actions underlying the joint bearing of surrounding rock and stacked lining structure in cirlular hydraulic tunnel,this study focuses on the three-layer stacked lining used in the Pearl River Delta Water Resource Allocation Project.The lining structure comprises an outer concrete segment,a self-compacting concrete filling layer(SCC),and an inner steel tube.Using the power series solution of plane elastic complex function theory and stress function analysis,we established a mechanical model considering the interaction between surrounding rock and lining as well as stress boundary conditions.We derived and solved the stress components at any point within the surrounding rock and each layer of the lining under combined excavation load and internal hydraulic pressure.This approach elucidates the load transfer mechanisms and behaviors of the stacked lining structure.We verified the accuracy of our method by comparing boundary stress results with numerical simulations.Finally,through parameter analysis,we examined how increased internal hydraulic pressure affects radial and circumferential normal stresses in the surrounding rock and the three-layer lining.Results manifest that when the surrounding rock and the three-layer lining work together to bear loads,both the radial and circumferential normal stresses exhibit a cosine distribution,while the shear stress follows a sine distribution.As the water pressure inside the water conveyance tunnel increases,the three-layer lining and surrounding rock become increasingly compressed in the radial direction,while the circumferential normal stress tends to become tensile and increases.The research findings provide a theoretical foundation for the design and construction of multi-layer lining systems in hydraulic tunnels.