裂纹扩展及合理布锚的试验研究

【作者】 林春金；

【导师】 朱维申；

【作者基本信息】 山东大学 ， 岩土工程， 2006， 硕士

【摘要】 岩石、混凝土、陶瓷和玻璃常常分布着大量的裂纹等缺陷，这些缺陷在荷载作用下造成裂纹的孕育、萌生、扩展和贯通，导致介质的强度和刚度降低。开展含有裂纹缺陷的岩石破坏过程研究，对评价岩石以及岩石工程的安全状态，了解岩土工程结构的稳定性以及采取合理的支护措施，都具有重要的理论意义和工程价值。 经典断裂力学的研究只涉及裂纹尖端引起应力集中所导致的裂纹扩展问题，在研究非均质介质中的裂纹扩展遇到数学上的困难，对于极不均匀性的岩石介质的裂纹扩展问题更难通过解析理论进行准确的描述。非均质裂纹扩展的数值计算方法虽然得以实现，但是模拟的效果和实际情况还有较大差异，物理试验方法仍然是解决裂纹扩展等问题的强有力工具之一。本文结合数值试验和物理试验开展了以下研究工作： 1．利用东北大学研制开发的软件RFPA^2D进行数值计算，对二维条件下雁行裂纹在不同相对分布情况进行了数值模拟；只变化裂纹内端点距离，得到雁行裂纹不同分布对试样强度的影响以及破坏模式临界值。 2．试验大量不同配比水泥砂浆材料，测试材料抗压强度、抗拉强度、泊松比、弹性模量，寻找到了脆性较好模拟岩石的砂浆材料。 3．利用试验成功的材料，制作出了含预置裂纹砂浆材料试件。利用电液伺服试验机和声发射设备，研究了不同倾角的内置单椭圆裂纹的破坏规律及裂纹角度对材料强度的影响。 4．在45度倾角的单椭圆裂纹扩展规律的研究基础上，对45度单椭圆裂纹试件进行加锚，加锚角度分为垂直裂纹和与裂纹成45度夹角，加锚位置在裂纹中部和两端。研究了单轴加载下锚杆对裂纹扩展的抑制效果；总结了不同加锚方式对材料力学参数的提高程度，对实际工程中锚杆加固提出了一些建议。更多还原

【Abstract】 Rock, concrete, ceramics and glass, as discontinuous inhomogeneous, anisotropic, and not elastic brittle medium, are typically made up of defected material containing flaws. Under different compressive stress, as the crack initiation, propagation, coalescence and interaction, the flaws may lead the strength and stiffness degradation of such medium. It is significant for engineering and academic study to investigate the rock failure process of medium containing flaws.In classical fracture mechanics, the research of crack growth only involves crack propagation caused by stress concentration from flaw tip, and the study of crack growth in inhomogeneous medium may meets mathematical difficulty, so it is deficient to get accurate analytical description .To study the crack growth in inhomogeneous medium with numerical method, the result is not according with the fact well. Experimental method is a powerful tool to solve the crack growth problem. In this paper, the two methods are combined to do the following research work:1 The echelon cracks with different distributing forms in two-dimension condition were simulated using the RFPA^2D developed by the DongBei University. The influence of different distributing forms on the sample strength and crack propagation pattern were studied only changing the distance between internal nodes in the cracks.2 Trying a great amount of mortar material with different proportion , and testing compressive&tensile strength value, Poisson’s ratio, elastic module of different samples, a material with fine brittleness were found out.3 Mortar material specimens containing flaws with developed material by myself, were made, Then we do some research about failure process of mortar material specimens which contain different angle single ellipse flaw and influence of flaw angle on the strength of mortar material., using acoustic emission equipment and serve-controlled test machine.4 Base on the research about ellipse flaw propagation at a = 45 ° , setting two bolts which angle is 45° and 90° with flaws in middle and end of flaws, the effect of bolting on propagation of rock crack in uniaxial compression were researched and the effect of different bolting on the enhancement of mechanics capability were summarized. Then we give some advice about reinforce with bolts in engineering.更多还原