岩体裂隙开挖卸荷扩展机理研究

岩体开挖卸荷作用导致岩体应力重分布,使得处于压剪状态的岩体内部原生裂隙失稳扩展,发生卸荷损伤。文章以岩体断裂力学为基础,考虑岩体开挖卸荷作用三种基本模式:(1)围压卸荷作用;(2)大主应力与围岩同时卸荷作用;(3)主应力方向旋转卸荷作用。采用岩体压—剪断裂理论研究这三种卸荷模式下岩体裂隙扩展的条件,阐述了岩体裂隙开挖卸荷扩展机理。最后,通过具体算例验证了本文方法的合理性,进一步得到三种典型开挖卸荷模式下岩体裂隙的启裂条件。     

蠕变条件下完整岩石的起裂和扩展准则

The mechanism and criterion of crack initiation and propagation of rocks were investigated by many researchers,And the creep behaviour of rocks was also theoretically and experimentally studied by some scientists and engineers.The characteristics of crack initation and propagation of rocks under creep condition.however,are very improtant for rock engineering and still not paid enough attention by researchers,In this paper,the criterion and mechanism of crack initiation and propagation under creep condition were investigated using specimens collected from sandstone rock formations outcropping in the Emei Mountain,the Sichuan Province of China.Cuboid specimens under three point bending were used in this investigation.All specimens were classified into four sorts and used for Mode-I fracutre of creep frcture tests.The experimental result shows that due to creep deformation.rock crack will inevitably initialt and propagate under a load of KI,which is less than fracture toughness KIC but not less than a constant(marked as KIC2),KIC2 indicates the ability of rock to resist crack initiation and propagation under creep conditions and is less than fracture tough ness KIC.defined as creep fracture toughness in this paper,KIC2 should be considered as an importnat parameter on design and computation of rock engineering.The microstructureal mechanism for crack initiation and propagation of rock materials under creep condition was introduced based on competitive model between softening effect and hardening effect,and the validity of test result was explained.The test result was also verified in rheological theory.When KI is more than KIC2 but less than KIC,rock crack will initiate and propagate after a time interval of sustained loading under creep condition.In order to find the relation between duration of sustained lading.which can lead to crack initiation and propagation,and the initial stress intensity factor KI,an unequal0interval time sequence forecasting and predicting model was introduced,and the relation was obtained for homogeneous and isotropic fine-grained red sandstone.Finally a modified fracture toughness formula was given,in which the influence of fracture process zone(FPZ) was fully considered.     

节理岩体锚喷支护作用的断裂力学分析和数值模拟

锚喷支护对岩体的加固作用在很大程度上是抑制裂纹的扩展。分别采用理论分析和数值方法对锚喷支护抑制裂纹的扩展进行了分析研究。首先在理论方面利用断裂力学理论分别分析了混凝土喷层和锚杆对应力强度因子的影响,并计算得到了锚杆的最佳安装角。然后利用ANSYS数值模拟了锚杆对裂纹的止裂作用。结果证明,本文的计算方法能够比较准确地反映出锚喷支护作用,计算的结果也与数值方法吻合的较好,可以用于指导支护优化设计和评价支护效果。     

FRP加固混凝土柱的健康评估方法研究

各种灾害的频繁发生,对基础设施的安全性提出了更高的要求。新型纤维复合材料（FRP）的应用提高了混凝土柱的抗疲劳肚能。该文基于断裂力学的理论,对FRP加固混凝土柱进行了疲劳分析,并提出了健康评估方法。     

沥青混凝土路面裂缝的研究现状

简要介绍了沥青路面使用现状及主要问题,有限元通用程序和有限单元应力强度因子法在沥青混凝土路面及沥青路面裂缝结构分析中的应用,并对沥青路面结构分析的发展方向进行预测。     

抽油杆杆体表面裂纹应力强度因子的研究

根据断裂力学中的应力强度因子来研究抽油杆杆体部位表面裂纹的变化,从而对抽油杆杆体部位表面裂纹缺陷进行定量评定;给出了用疲劳裂纹扩展法求应力强度因子,其优点是可以在非常接近真实裂纹构件的情况下,用实验分析方法来研究应力强度因子问题。     

断裂力学中一个基本问题的新解

文章利用新的方法研究了断裂力学中的一个基本问题 ,即利用Schmidt方法重新求解了Lowen grub研究的条状物体中的一个裂纹问题 ,这一解适用于任何厚度的条状物中的裂纹问题 ,拓展了Lowengrub解的适应范围 (Lowengrub的解仅适用于厚的条状物体中的裂纹问题 ,即适用于δ =h/l 1的情况 ,h是条状物体半厚度 ,l是裂纹的半长 )     

断裂力学教学方法改革与实践

断裂力学是固体力学的一个重要分支,是以弹塑性理论为基础的一门专业技术课,课程内容涉及的知识面广,理论较难理解。为了更好地做好断裂力学教学工作,根据断裂力学课程的特点,对教学方法进行了研究和总结,力求能激发学生的学习热情,提高课堂教学效果,培养学生的创新意识和能力。     

高速剪切裂纹扩展方向的研究

本文将断裂力学关于裂纹的有关理论引用到高速剪切研究中,基于断裂力学中应变能密度因子理论的研究,分析了高速剪切的裂纹扩展规律及断面质量改善的机理,进而提出了规则高速剪切定律及规则剪切条件下的裂纹扩展方向。