寒区边坡冻融岩体裂隙扩展特性及加固方式试验研究

发布时间：2018-04-15 17:20

本文选题：英安岩 + 冻融循环　；参考：《成都理工大学》2017年硕士论文

【摘要】：在寒区边坡工程中,边坡岩体常年经受剧烈的冻融循环作用,由此导致岩体裂隙的扩展发育极大的影响了工程的建设和安全运行。近年来,对冻融条件下岩体裂隙的加固多依据常规工程经验,少有理论支撑,因此,研究循环冻融条件下岩体裂隙的损伤扩展特性以及加固方式,对寒边坡工程具有重要意义。本文依托导师项目,以西藏某水电站坝址区英安岩为研究对象,通过饱水状态下英安岩岩石的冻融循环试验、单轴压缩试验、相似材料试验、X射线三维激光扫描试验及相似材料裂隙加固等试验,系统研究了英安岩在冻融条件下的裂隙微观扩展规律和相似材料在冻融条件下的裂隙宏观扩展规律,并结合两种研究成果及其物理力学性质,探讨寒区工程岩体裂隙的加固方式,主要研究结论如下:(1)英安岩试样随着冻融循环次数的增加,其质量呈现出先升高后降低,最终趋于稳定的趋势,冻融后质量较初始质量略微提高;(2)由英安岩试样扫描前后成像结果对比可以得出,研究区英安岩原生孔隙及裂隙十分稀少,但其矿物颗粒胶结程度较弱,在冻融循环条件下会有不同程度的析出。由此,试样内部的孔隙呈现出单向扩展、双向扩展以及膨胀扩展的规律,同时较大裂隙扩展会对四周较小裂隙产生挤压作用,导致部分微小裂隙闭合;(3)裂隙岩体的冻融损伤劣化模式主要有三种类型:颗粒剥落模式、龟裂模式、沿原始裂隙开裂模式;单个冻融循环岩石环向应变随时间变化可分为五个阶段:冷缩阶段、内部水体冻结阶段、冻胀阶段、融缩阶段、平衡稳定阶段;(4)裂隙加固方式研究:在寒区裂隙加固工程中,锚杆支护角度在相当程度上会影响到锚固力的作用,锚杆与裂隙夹角越小,作用于裂隙的锚杆力越低,因此宜垂直于裂隙进行锚杆支护;使用无机超细微粒组成的高性能灌浆材料对裂隙进行压力注浆,可以对边坡碎裂岩体起到螺栓接连作用并防止水的渗入;(5)建议对浅表层部分碎裂岩体进行开挖放坡,并布置排水孔与截水沟,对开挖区域范围外的边坡,其表面多为碎裂岩体的部分,采用挂网锚喷防护。此外设计时应考虑冻融对锚杆加固效果的影响,并缩短位移监测周期,以防出现锚杆失效的情况。
[Abstract]:In the cold region slope engineering, the slope rock mass is subjected to severe freeze-thaw cycle all year round, which leads to the expansion and development of rock mass cracks, which greatly affects the construction and safe operation of the project.In recent years, the reinforcement of rock fissures under freeze-thaw conditions is based on the experience of conventional engineering and there is little theoretical support. Therefore, it is of great significance to study the damage and propagation characteristics and reinforcement methods of rock fractures under cyclic freezing and thawing conditions for cold slope engineering.Based on the tutorial project, this paper takes the dacite in a dam site area of a hydropower station in Tibet as the research object, through the freezing and thawing cycle test and uniaxial compression test of the dacite rock under the condition of saturated water.In the similar material test, X-ray 3D laser scanning test and similar material crack strengthening test, the microcosmic propagation law of the crack in the permafrost and thawing condition and the macroscopic crack propagation law of the similar material under the condition of freezing and thawing are systematically studied.Combined with the two kinds of research results and their physical and mechanical properties, the reinforcement methods of rock mass cracks in cold region are discussed. The main conclusions are as follows: 1) with the increase of freezing and thawing cycles, the quality of rock samples increases first and then decreases.Finally, the trend tends to be stable, the quality after freezing and thawing is slightly higher than the initial quality.) from the contrast of the imaging results before and after scanning, it can be concluded that the primary pores and fissures in the study area are very rare, but the degree of mineral particle cementation is relatively weak.In the freeze-thaw cycle conditions, there will be different degrees of precipitation.As a result, the pores in the specimen exhibit the law of unidirectional, bidirectional and expansion expansion. At the same time, the larger crack propagation will produce the squeezing effect on the surrounding smaller fractures.There are three main types of freeze-thaw damage deterioration mode of fissured rock mass: grain spalling mode, crack mode, and crack mode along the original crack;The variation of circumferential strain of single freeze-thaw cycle rock with time can be divided into five stages: cold contraction stage, internal water freezing stage, frost heaving stage, thawing stage, equilibrium stabilization stage and so on.The angle of bolt support will affect the effect of anchor force to a certain extent. The smaller the angle between bolt and crack, the lower the bolt force acting on fracture, so it is appropriate to support bolt vertically in fracture.The use of high performance grouting material composed of inorganic ultrafine particles to grouting fractures can act as a bolt connection to the fractured rock mass of slope and prevent water from infiltrating into the rock mass.) it is suggested to excavate and release the shallow surface fractured rock mass.The drainage holes and water cut ditches are arranged. The surface of the slope outside the excavation area is mostly the part of the fractured rock mass.In addition, the effect of freezing and thawing on the reinforcement effect of anchor rod should be considered, and the monitoring period of displacement should be shortened to prevent the failure of anchor rod.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45;TU472

【参考文献】