导流洞堵头力学效应及设计影响因素分析

Analysis of mechanical effects and influence factors of design for a diversion tunnel plug

目前堵头设计还没有统一的标准和准则,多数堵头设计长度过分偏于安全.依托金家坝水电枢纽导流洞封堵工程,利用ANSYS软件建立了堵头和围岩的三维有限元模型,全面分析堵头的力学效应.分析表明:堵头总体上呈受压状态,而且拉压应力均较小,不会超过堵头混凝土本身的强度;上游水压力主要由堵头与围岩的黏聚力和接触面的摩擦作用共同承担.在此基础上,考虑围岩附加抗力,分析了围岩等级、堵头混凝土等级、堵头楔角等因素对堵头设计的影响.结果表明:适当的楔角是发挥围岩附加抗力的必要条件,围岩等级的提高也有利于堵头的稳定性,而单纯提高堵头混凝土的强度等级并不能提高堵头的抗滑稳定性.

At present, there are no unified design standards and criteria for the plugs, so the design length of the most of plugs is too safe. In this paper, relying on Jinjiaba hydropower diversion tunnel plug project, a 3D finite element model for the plug and surrounding rock is established by use of ANSYS software, and the mechanical effects of the plug are analyzed comprehensively. Analysis results indicate that the plug is under pressure, and that tension and compression stresses are smaller and no more than strength of the plug concrete itself. Cohesion and friction on the contact surface of the plug and the surrounding rock have shared the water pressure. On this basis, an additional resistance of the surrounding rock is taken into account, and design influences of the plug, such as a grade of the surrounding rock and the plug concrete, and a wedge angle of the plug are analyzed. The analysis results show that the proper wedge angle is the necessary condition to take advantage of the additional resistance of the surrounding rock; and the improvement of the grade of the surrounding rock is beneficial to the stability of the plug, but the improvement of concrete strength grade does not improve the anti-sliding stability of the plugs.