水工隧洞不同围岩等级力学性能研究

Study on Mechanical Properties of Different Surrounding Rock Grades in Hydraulic Tunnel

为探究围岩等级下降对水工隧洞内力及变形产生的影响,以实际工程中隧洞有限元仿真分析所涉及的问题为例,采用地层结构法模拟隧洞开挖过程,选择典型断面运用三维有限元软件Abaqus,对Ⅲ类和Ⅳ类围岩在相同计算工况及荷载作用下进行分析计算,取隧洞计算结果的最大值进行比较。结果表明,与Ⅲ类围岩相比,Ⅳ类围岩等效位移增加了58.84%,等效塑性应变减少了25.74%;支护的水平位移、竖直位移、轴力和弯矩都增加了,除弯矩增加了139.94%外,其余的增长率均在25%~35%之间,锚杆的轴力相对增加最小,增加了19.32%。在实际工程中,需对支护弯矩值的变化给予重点关注,以此加强隧洞支护作用和安全效果。

In order to explore the influence of rock mass grade decline on the internal force and deformation of hwtraulic tunnel, the stratum structure method is used Io simulate tunnel excavation, and the typical sections of tunnel under Grade Ⅲ and Ⅳ surrounding rock arc calculated respectively by using three-dimensional finite element software of Abaqus under same calculation conditions and load conditions. The calculated maximums are compared. The results show that, （a） compared with Grade I11 surrounding rock, the equivalent displacement of Grade IV surrounding rock is increased by 58.84%, the equivalent plastic strain reduced by 25.74% ; （b） the horizontal displacement, vertical displacement, axial force and bending moment of supporting are all increased with a magnitude of 139.94% for bending moment and 25% to 35% for remaining factors; and （c） the axial force of anchor rod has a relative minimum increase of 19. 32%. Therefore, it is necessary to pay special attention to bending moment change of supporting in actual project for strengthening the supporting role and safety of tunnel.