【作者】 滕丽；

【导师】 张建海；

【作者基本信息】 四川大学 ， 岩土工程， 2003， 硕士

【摘要】 我国大型水电工程多建在高山峡谷中，具有水头高、流量大，泄洪功率巨大等显著特点。泄洪洞下泄流量大、洞内流速高，能否安全运行，将直接影响土石坝的安全，也是整个水利枢纽能否正常安全运行的关键。瀑布沟水电站位于四川省汉源县境内大渡河中游，装机总容量3300MW，总库容50.6亿m³。工程以发电为主，兼有防洪、拦沙等综合效益，拦河大坝为直心墙土石坝，最大坝高186.0m。泄洪洞布置于左岸地下厂房的花岗岩体内，洞线顺直，隧洞为无压明流洞，断面形式为圆拱直墙型。 瀑布沟泄洪洞出口段右侧壁最小厚度仅约10.0m，左侧山体高达100.0m，隧洞偏压问题十分突出。隧洞偏压对边坡稳定性、隧洞出口段衬砌的影响以及偏压所致变形不对称性是工程非常关心的问题。考虑到岩体的不连续性、非均匀性、应力—应变关系的非线性特性以及力学性质的各向异性，本文采用非线性有限元法，计算围岩的变形和应力，定量评价岩体的稳定性，并追踪岩体破坏状态的发展演变过程。 非线性有限元法在处理复杂结构、复杂边界及荷载条件、非线性问题方面具有独特的效能，并能获得更为详尽、准确的结果，现已成为隧洞计算最有效的方法之一。本文根据泄洪洞总体施工方案和隧洞出口的地质条件，建模时严格模拟岩层界面、地形、F₁断层结构面的产状，以及泄洪洞体形和各种工程处理措施，充分反映了斜坡地形地质条件对隧洞的影响。在有限元计算中将泄洪洞分三级开挖用以模拟施工开挖过程，采用遍在节理包络强度模型模拟岩体材料，运用点强度储备安全系数法研究隧洞开挖过程中边坡的稳定性和隧洞的偏压应力。本文的主要工作：（1）基于工程的地质CAD剖面图四川大学硕士学位论文形，建立二维有限元网格图，利用AutoLIsP和Fortran语言开发二维有限元前处理优化程序，实现二维有限元网格节点的自动编码、点差优化排序，和网格单元编码和材料信息的自动生成，使复杂工程中有限元计算前处理的功效得到较大的提高。（2）分析计算了施工开挖前围岩的应力情况和自然边坡稳定性;（3）在边坡进行支护和不支护、分级开挖无衬砌和有衬砌等各种工况下，分别计算围岩、边坡稳定性和结构安全性，并对支护方案作出评价;（4）在运行、检修和地震工况下，对比分析衬砌厚为1.5m、2.0m时围岩稳定性、结构安全性，推荐衬砌厚度方案。（5）将W类围岩指标改为V类围岩指标作力学参数敏感性分析。 通过综合分析，建议在泄洪洞开挖前，先期进行岸坡加固，同时，在泄洪洞分级（步）开挖过程中，及时作好一次喷锚支护，在上半洞喷锚支护完成条件下进行下半洞开挖，有条件时尽可能及早进行二次硅衬砌。本文研究成果已得到工程应用。更多还原

【Abstract】 Many large scale hydropower stations of our country are built in gorges among high mountains. High hydraulic head, large-discharge, huge power of flood discharge are notable characteristics of these water powers. The operational safety of earth-rock dam, or even the whole hydraulic project, is directly influenced by discharge tunnel. Pubugou hydropower station, located in Hanyuan county, Sichuan province, has 3300MW power capacity, and 5060Mm3 total storage capacity. The project is built for electricity generation, flood control, sand barrage, etc. The maximal height of the vertical core-walled rockfill dam is 186m. The free-flow discharge tunnel, whose form of section is circular arch and straight wall, is located in granite rock below underground workshop of left hillside.Because the minimal thickness of the right side of tunnel is only 10m and the height of the left side of the tunnel is over 100m, the surrounding pressure distribution at the discharge tunnel of Pubugou Hydropower Station is much unbalanced. The unbalanced pressure of the tunnel and the stability of the slope during the course of excavation are studied using nonlinear finite element method (FEM). The nonlinear model strictly simulates the overall geological condition, such as fault and fissures, the tunnel’s section form and various schemes of construction. The stability of the slope, under deformation of excavation and the unbalanced stress of the tunnel, is evaluated and appraised by point safety factor distribution.The major works of this thesis are as follows: (1) Using AutoLISP andFortran, a 2D mesh generation program is developed to achieve automatic node coding and obtaining the information of element and corresponding material.(2) The unbalanced stress state and stability of the slope before excavation are calculated and analyzed. (3)Stability analysis of surrounding rock and slope, and appraisal of structure safety are carried out, under the conditions of support or non-support, with lining or without lining. (4)The stress state of 1.5m thick lining is compared with that of 2.0m thick lining. (5)By degrading rank IV surrounding rock to rank V rock, the sensitivity of slope stability to mechanical parameter is also checked.It’s recommended to reinforce the slope before excavation, to bolt and to shotcrete in time during excavation, and to excavate the lower-half of tunnel after bolting and shotcreting of the upper-half, and to make the second shotcrete lining as early as possible. These suggestions have been adopted in practice.更多还原