【作者】 刘麟；

【导师】 张建海；

【作者基本信息】 四川大学 ， 岩土工程， 2005， 硕士

【摘要】 围堰堰基的稳定性是影响施工正常进行的关键因素。六库水电站纵向碾压混凝土围堰堰基座于冲积层上,基岩为挤压破碎岩体,堰基基岩变模很低(E0=0.04～0.048Gpa),地质条件差,因此六库水电站纵向碾压混凝土围堰基础稳定是本工程的关键技术问题。本文采用二、三维非线性有限元法对其渗流、应力应变及稳定性进行了计算分析,并用粒子群优化算法对堰基边坡的稳定性进行了研究。研究内容和计算成果包括以下几个方面: 1.采用非线性有限元法对围堰三个典型二维剖面和三维整体渗流场进行了分析。分析结果表明,二、三维渗流场分析所得各剖面水头分布和渗压分布规律相近。均表现为水头在两道防渗墙处迅速折减;而在砂卵冲积层和基岩处则衰减缓慢。两道防渗墙的防渗效果显著。2.首先采用二维非线性有限元法对围堰三个典型二维剖面的应力和应变进行分析,在此基础上再计算防渗墙和垫层的剪力、轴力和弯矩,对防渗墙和垫层的配筋方案进行验证和改进。计算结果表明,由于堰基基岩变模很低,三个典型剖面的堰体位移均较大;堰体及堰基大、小主压应力随高程降低而增大,在围堰垫层与两道防渗墙的接头处附近存在应力集中现象;研究表明应加大垫层的配筋率。3.采用强度储备法分析了各工况下围堰三个典型二维剖面和三维整体的破坏机理以及破坏发展路径,最终确定堰基的强度储备安全系数。汛期水位下,三维强度储备法得出的整体抗滑安全系数为Kc=1.80。4.对粒子群优化算法这一新颖的人工智能搜索方法在边坡工程中的应用进行研究,并将之应用于本课题围堰边坡的稳定性分析研究中。论证了粒子群优化算法在边坡工程中的实用性。更多还原

【Abstract】 The stability of cofferdam’s foundation is the critical factor influencing construction process. The foundation of longitudinal RCC cofferdam in Liuku hydropower station is sandstone alluvium and the bed rock is cracked. The elastic modulas of cofferdam’s bed rock is very small (E0=0.04～0.048Gpa),so the stability of RCC longitudinal cofferdam foundation in Liuku hydropower station is the critical technique problem. The seepage、stress-strain and stability are studied using 2D and 3D non-linear finite element method; then particle swarm optimization method is applied to the stability research of cofferdam’s slope. The main research contents and achievements are as follows: 1.The seepage field of three typical 2D sections and 3D unit of cofferdam’s foundation is studied using finite element method. The result shows that the general pattern of water head and seepage distribution derived from 2D and 3D seepage analysis is similar. The regularity is that the water head falls down rapidly through two anti-seepage walls, but subsides slowly in sandstone alluvium and bed rock. The engineering effect of two anti-seepage walls is notable. 2.Firstly the stress-strain state of three typical 2D sections is studied using 2D non-linear finite element method. Then the shear、axial force and bending moment of anti-seepage walls and cushion are calculated on this basis and the reinforcement scheme of them is verified and improved. The result indicates that the displacement of cofferdam body is large due to low elastic modulas of the bed rock in cofferdam’s foundation; maximum and minimum principal compression stress of cofferdam body and its foundation is increasing as the elavation falls; the stress concentration exists in the joint of cofferdam body and anti-seepage walls; the reinforcement of cushion should be increased. 3.Strength reserve safety factor method is adopted to study the failure mechanism and failure process paths of three typical 2D sections and 3D unit under several working conditions. Finally the strength reserve safety factor of cofferdam’s foundation is obtained. In flood season, the safety factor Kc of cofferdam’s foundation is 1.80. 4. The application of particle swarm optimization method that is a new swarm intelligence searching method in searching for critical slip surface of slope engineering is studied and applied to the stability analysis of the cofferdam’s slope. It demonstrates the practicability of particle swarm optimization method in slope engineering.更多还原