内水压力下水工隧洞衬砌与围岩承载特性研究

衬砌与围岩是水工隧洞的主要组成部分,内水压力是其承担的主要荷载之一。采用轴对称计算模型,以衬砌与围岩间接触应力状态为判断标准,研究了衬砌混凝土开裂前后围岩渗透系数、变形模量等材料参数对衬砌与围岩联合承载特性的影响,详细地介绍了透水衬砌的设计方法和计算过程,以混凝土最大裂缝宽度为控制标准,编制了透水衬砌结构计算与配筋设计程序,并给出了算例验证。计算结果表明,围岩渗透系数是隧洞结构设计的关键,与围岩变形模量具有同等重要作用;围岩透水性越差或变形模量越低,衬砌与围岩越容易脱开;与混凝土开裂前相比,混凝土开裂后,衬砌与围岩更容易脱开;与钢板衬砌方案相比,钢筋混凝土衬砌方案可以很大程度地减小钢材用量;建议高压钢筋混凝土衬砌隧洞设计、施工时,应尽可能地保持围岩的完整性,并进行细致周密的固结灌浆,以增强围岩抗渗能力。

Study of combined bearing characteristics of lining and surrounding rock for hydraulic tunnel under internal water pressure

Internal water pressure is one of the main kinds of loads acting on hydraulic tunnel, which consists of lining and surrounding rock. The axisymmetrical model is adopted and the corresponding formulas are carried out. The radial stress on interface is assumed as the flag to tell the combined bearing capability of lining and surrounding rock. Then the influence of rock permeability and deformation modulus on the combined bearing characteristic of lining and surrounding rock is discussed. The design method and process are described in detail. According to the limit of maximum width of concrete crack, a program to calculate pervious lining stresses and to carry out the reinforcing bars design is developed and compiled. A certain tunnel is analyzed as an example and a certification of design program is provided. Finally some conclusions are drawn as follows. Rock permeability is as important as deformation modulus in tunnel lining structure design. The possibility of lining deviating from rock becomes larger when rock permeability becomes poorer and deformation modulus softer. And the possibility of lining deviating from rock also becomes larger when the concrete cracked. A great amount of steel can be saved through the reinforced concrete lining scheme than the steel lining one. To enhance rock integrity and impermeability, some advices are suggested, such as reducing excavation disturbance, adopting fine and complete consolidation grouting.