【作者】 郑春梅；

【导师】 朱维申；

【作者基本信息】 山东大学 ， 工程力学， 2010， 博士

【摘要】 当前,国内外岩体工程发展迅速,越来越多的能源、交通、矿山、水利和国防工程建造在岩石地区,其工程设计、施工、稳定性评价和岩体加固等直接依赖于对岩体的强度、变形、渗透性及破坏规律等特征的研究。裂隙岩体由于参数的随机性、模糊性以及赋存环境的复杂性使得岩体中的地下水运动具有不连续性,渗透具有非均质性和各向异性。而岩体裂隙作为岩体的主要渗透通道,显著地受应力环境的影响。众所周知,由于工程的开挖,工程荷载施加于岩体之上,改变岩体内部应力场的分布,使得岩体发生变形或破坏。岩体变形或破坏又使得岩体中地下水的渗透特性发生变化。相应地,岩体渗透特性的变化又进一步改造着岩体应力场,从而体现了两场之间的耦合关系。岩体应力场与渗流场的相互作用,影响和决定工程体的稳定性、工程的正常运转、工程活动的安全性及工程的造价高低等。国内外重大失事事故说明研究人类工程作用力、岩体地应力及地下水渗透力相互作用的重要性。目前,裂隙岩体渗流与应力耦合研究已成为众多学者致力挑战的课题,也是岩体力学界的热点问题。本文把岩体看作不连续介质,从理论分析、数值模拟和试验验证三个方面,对裂隙岩体的渗流场与应力场之间的相互作用机理进行了深入系统的研究,具体内容有如下几个方面：(1)从裂隙岩体渗流场与应力场耦合的角度出发,定量化分析了岩体裂隙的几何特征和裂隙岩体的渗透特性,研究了单裂隙在正应力、剪应力和三维复杂应力条件下的渗流与应力耦合特性,为渗流场与应力场的耦合研究奠定了基础。(2)介绍了非连续变形分析方法(DDA)的基本原理和数值方法,分析了DDA方法的不足,采用高阶非常应变单元改进位移函数,为提高DDA的计算精度提供了理论基础。此外,为弥补DDA中的罚函数法的不足,采用增广Lagrange乘子法代替DDA中的罚函数法实现块体交界面上无嵌入,最后通过经典算例验证了本文程序的正确性。(3)应用二维裂隙网络稳定渗流数学模型,求解裂隙网络渗流的渗透矩阵,并用试验结果验证了该方法的正确性,为进一步求解裂隙网络自由面位置和进行渗流应力耦合分析奠定了理论基础。通过数值分析,对离散介质岩体渗流规律进行了探讨,发现主干裂隙在裂隙岩体渗流中起着控制渗流场分布的作用。最后应用改进的初流量法,编制程序求解裂隙岩体网络渗流自由面,并与解析解相比较,验证了该程序的可靠性。(4)在DDA力学计算原理和裂隙网络渗流分析的基础上,建立了基于DDA的裂隙岩体渗流应力耦合分析模型,研究了裂隙岩体变形对地下水运动的影响以及渗流场与应力场共同作用下裂隙岩体结构的变形破坏特征。阐述了DDA在水力耦合计算中水力开度和水头压力的计算方法。最后将该模型用于经典算例分析,验证了本文提出的基于DDA的水力耦合计算方法的可靠性。(5)实现了DDA中施工开挖和全长锚固锚杆的模拟。数值计算结果表明,改进的非连续变形分析方法对隧道的开挖支护是有效的,全长锚固锚杆比端部锚固锚杆的锚固效果要好。锚杆的轴力变化与隧道的变形一致,这证明改进的DDA方法是正确的和合理的。更多还原

【Abstract】 With the rapid development of rock engineering at home and abroad, more and more energy, transportation, mining, water conservancy construction and national defense have been built in rock area at present, whose engineering design, construction, stability evaluation and rock reinforcement etc depend directly on the characteristics such as strength, deformation, permeability and failure law of rock.The groundwater movement in fractured rock mass is of discontinuity, heterogeneity and anisotropy due to its randomness, fuzziness and corresponding complex geo-mechanical environment. While the permeability of rock fracture is significantly affected by stress environment as the main permeability channel in rock It is well known that engineering excavation causes the distribution of internal stress field and deformation or damage of rock. However, rock mass deformation or destruction has changed the permeability of groundwater in rock. Accordingly, changes of permeability in rock further transform the stress field of rock mass, which reflects the coupling relationship between them. The interaction between stress field and seepage field influences and determines the stability of engineering body, the normal operation of the project, the safety of project activities and high low construction costs. Major crash at home and abroad shows the importance of studying the interaction among force of human engineering, in-situ stress and groundwater seepage force.Hydro-mechanical coupling of fractured rock mass has been not only a subject that many scholars are challenging, but also a hot issue in mechanical study. Based on the discontinuous deformation analysis, the paper has studied systematically and deeply the coupling mechanism between seepage and stress field of fractured rock mass with theoretical analysis, numerical simulation and experimental validation. The work in the present paper can be summarized in the following.1. From the aspects of the coupling of seepage and stress of fractured rock mass, the geological and permeable characteristics of fractured rock mass have been quantitatively analyzed. Hydro-mechanical coupling properties under the circumstances of normal stress, shear stress as well as three-dimension (3D) complex stress state are analyzed, which lay firm foundations for the further coupling study between seepage and stress field. 2. The paper reviews some of the basic concepts of the DDA method. Then, corresponding improved measures are presented in the following aiming at disadvantages of the original procedure code. At first, the displacement function is improved by using higher order block element corresponding to non-strain field, which provide a theoretical basis for enhancing the accuracy of DDA calculations. Then, contacts between blocks have been modeled using an augmented Lagrange multiplier method instead of the penalty method to prevent interpenetration of the blocks. Finally, the correctness of this program has been demonstrated through the classic example.3. The seepage matrix of fracture network flow has been solved by using mathematical model of two-dimensional fracture network seepage. The validity of the method has been verified by comparing with the experiment, which lays theoretical foundations for the further coupling study between seepage and stress field. And the seepage law of discrete media is studied through numerical analysis. It is found that main fracture plays a role in controlling the distribution of seepage field. The seepage free surface of fracture network is solved by using the modified initial flow method. Then, the reliability of the program is verified by comparing the numerical and analytical solution.4. Based on the mechanical theory of DDA and fluid flow analysis of fractured network, hydro-mechanical coupling analysis model is established in the paper. Moreover, the paper has studied the effect of the deformation of fractured rock mass on the groundwater flow, its failure characteristics of the degeneration under the action of seepage and stress field. At the same time, hydraulic aperture and fluid pressure in hydro-mechanical coupling are formulated. Finally, hydro-mechanical coupling with DDA method proposed in this paper is demonstrated to be reliable and effective through the classic model.5. The full length rockbolt and excavation have been implemented in DDA method. The simulation results indicate that the modified discontinuous deformation analysis (DDA) method is effective for the reinforcement of tunnel. Furthermore, the change of axial force is consistent with the deformation of tunnel, which proves that the modified discontinuous deformation analysis (DDA) method is reasonable and correct. It is found that, in general, the anchoring effect of the full lenth rockbolt is better than that of the point anchoring rockbolt.更多还原