水电站引水隧洞衬砌结构三维有限元分析

3D Finite Elements Analysis for the Hydropower Projects of Diversion Tunnel Lining

根据某水电站引水系统实际情况,采用ANSYS三维非线性有限元法,建立其引水系统中新建引水隧洞的三维有限元模型;并对引水隧洞的衬砌结构进行分析。验证衬砌方案和支护参数的合理性;同时提供衬砌配筋计算结果及优化建议,论证现有衬砌和支护方案合理性,补充和完善加固处理措施。结果表明,引水隧洞各段衬砌在各个工况下,水平位移最大值为0.41 mm,出现在侧面;垂直向最大位移为-6.53 mm,出现在顶拱处。衬砌最大第一主应力为拉应力,其值为2.33 MPa,发生于工况四,出现在顶拱处;衬砌最大第三主应力为压应力,其值为-8.19 MPa,发生于工况二,出现在衬砌侧面。由于衬砌C25混凝土的抗压强度为17 MPa,故衬砌结构安全。衬砌采取单层筋布置,各段环向配筋Φ20@200 mm,纵向钢筋Φ12@300 mm,考虑到方圆渐变段的应力状态较为复杂,优化设计后建议采用50 cm厚的衬砌方案。

According to the actual situation of a hydropower projects water diversion system, the three dimensional finite element model of the newly diversion tunnel in the diversion system is established and the lining structure of the diversion tunnel is analyzed, and the rationality of the lining schemes and support parameters is verified, by adopting ANSYS 3D nonlinear finite element method （FEM）. Meanwhile, the lining reinforcement calculation results are provided to demonstrate the rationality of existing lining support scheme, to supplement and perfect the reinforcement measures. The results show that, for various conditions of each lining paragraphs of the south diversion tunnel section, the maximum horizontal displacement is 0. 41 mm in the middle of the side wall, and the maxi- mal perpendicular displacement is -6.53 mm in the crown. The greatest first principal lining stress, the value of 2. 33 MPa, occurring in fourth working conditions, appearing in the top arch, is tensile stress; The greatest third principal lining stress, the value of -8.19 MPa, occurring in second working conditions, appearing in the side lining , is compressive stress. Lining of C25 concrete compressive strength is 17 MPa, so the lining structure is safety. Single-layer reinforcement is introduced in lining, Hoop reinforcement Φ20@ 200 mm and longitudinal rein- forcement Φ12@ 300 mm are used in each paragraphs. Due to the complication of the transition region stress states, 50 cm thicks lining scheme are recommended after optimization designs.