【作者】 冯文文；

【导师】 李守巨；

【作者基本信息】 大连理工大学 ， 工程力学， 2008， 硕士

【摘要】 结合白山水电站地下厂房开挖工程,在现场地质调查和场区地勘资料分析的基础上,根据工程区地质力学环境条件,建立了能够反映研究区地貌、岩体结构和地应力环境条件的力学模型,采用ANSYS有限元软件对地下厂房的开挖和支护过程进行数值模拟分析。对地下厂房开挖的数值模拟主要是计算开挖面围岩变形情况和衬砌的应力和荷载以及监控开挖面围岩的稳定性。地下洞室的开挖是将开挖边界上的初始应力释放,从而引起洞室围岩的应力场重新分布。对地下厂房洞室围岩的稳定性进行分析,采用二维弹性有限元模型和分六层开挖方式模拟开挖方式。通过有限元数值模拟计算出每一步开挖边界上节点力,并作为下一步开挖的等效节点力施加在开挖边界上。数值模拟结果表明,开挖过程中进行支护可以改变应力场和位移场分布,明显的减小围岩的拉应力集中区域。现场监测的主要目的是:监控洞室变形、检测选择的施工方式是否得当、量测结构构件中的应力发展、掌握洞室围岩的变形情况,并指出是否需要对围岩和支护进行加固。使用多点位移计对开挖过程中的围岩变形情况进行监测。监测结果表明,使用喷射混凝土支护可以保证围岩的稳定性。从围岩变形的监测结果和计算结果对比可知,监测结果和计算结果比较吻合。根据有限元数值模拟结果,计算衬砌的强度安全系数,研究衬砌厚度变化对其安全系数和结构稳定性的影响。结合工程设计规范标准,探讨最小衬砌安全厚度,对支护结构的安全性进行分析。更多还原

【Abstract】 The geomechanics environment conditions of the Baishan Hydropower Station powerhouse are analyzed based on the local geology research and the analysis of geologic prospecting data. A mechanical model is developed to depict the actual conditions of the research area. The excavation and support processes are simulated by the ANSYS.The main problems of simulation on excavation of powerhouse are the evaluation and control of deformations and stability of excavation front, loads and stress in the lining. In order to investigate stability of surrounding rock of cavern, finite element model and sequential excavation procedures were proposed. The excavation process is simulated step by step.The numerical modeling relies on a two-dimensional analysis, implementing elastic constitutive model. The excavation process is divided into six loading steps for simulation of the stress redistribution due to excavation.The variation due to the excavation of the stress state in the rock mass can be evaluated through a finite element analysis in which equivalent nodal forces, corresponding to the release of the initial stress, are applied to the contour of the cavern. Stresses in the excavated elements are converted into forces along the excavation boundary at each stage representing the construction advance. The numerical simulation results show that the lining has obvious influence on the distribution of displacement and first principal stress of surrounding rock and makes the tensile stress zones decrease.The main objectives of in-situ monitoring include: to control the deformations of the cavern, to verify that the appropriate excavation method was selected, to measure the development of stresses in the structural members, and to indicate progressive deformations, which require support strengthening. In monitoring the stability of cavern, the displacements of surrounding rock were measured during excavation. The field measurement results show that the surrounding rock of cavern is stable while the shotcrete was designed as the supporting structures. By comparing the numerical deformations with measured ones, the numerical simulated results agreed well with in-situ measured values. The simulation of excavation is carried out by using the numerical method. The internal force and safety factor of the lining are calculated to evaluate structure security. The effect of thickness changing on lining safety factor and structure stability is discussed.更多还原