200MPa级高强人造岩体制作技术研究

发布时间：2018-07-27 13:00

【摘要】：随着机械破岩技术在地下工程中的广泛应用,岩石破碎机理研究迅速成为国内外研究热点。由于现场大体积岩块取样困难,室内人造围岩的研制亟待解决。为此,本文开展了高强人造岩体的制作技术研究,解决了现场大体积岩样难取的问题。首先,通过试样试验对比分析,确定了活性粉末混凝土(简称“RPC”混凝土)最优配合比及最佳的养护制度。其次,利用数值模拟方法,通过研究大体积岩体内部温度应力场分布规律,得到可以减小大体积岩体内部拉应力的有效措施。本文的主要研究成果如下:(1)常压养护条件下试样试验。分别对RPC混凝土配合比设计过程中石英砂的细度模数、减水剂掺量、硅灰与粉煤灰掺量比、砂胶比、水胶比、复合型矿物掺和料掺量和膨胀剂掺量等7个因素进行单因素分析,得到各因素对RPC混凝土的流动性和抗压强度的影响规律。基于上述两种指标,得到常压养护条件下RPC混凝土的最优配合比。(2)不同养护条件下的试样试验。通过研究了4种不同的养护条件下RPC混凝土抗压强度与孔隙率的变化规律得知,高温高压较高温养护条件下,RPC混凝土的抗压强度增长更大(其中水胶比越低,效果越明显),孔隙率减小更多。这说明高温高压养护可以改善了RPC混凝土的微观结构,提高了RPC混凝土的致密性,进而提高自身的抗压强度,据此提出了高温高压的养护制度,并获得了强度可达200MPa的RPC混凝土。(3)数值模拟研究结果表明:1)对比不同尺寸的岩体内部的温度场分布规律,结果表明中等体积岩体无论给定何种外边界,其内部的温度场接近均匀的温度场;而大体积岩体内部存在较大的温度梯度。2)通过对比大体积岩体在升温、温度保持和降温阶段其内部的温度应力场分布规律,得出大体积岩体在降温阶段外表面产生较大的拉应力。3)通过对比分析三种不同的降温降压方式,结果表明先降温后降压方式能够有效减小大体积岩体内部的最大拉应力值。4)通过对降温降压速率进行控制,得出同时降低降温降压速度可有效减小大体积岩体内部的温度应力的结论。综合全文研究,通过试样实验研究给出了最佳的RPC混凝土配合比,提出了最佳的养护制度,通过数值模拟得到了最优的降温降压路径,对制作大体积无宏观缺陷的高强人造岩体具有指导意义,为实验室开展机械破岩研究提供了前提条件。
[Abstract]:With the wide application of mechanical rock breaking technology in underground engineering, the research on rock breaking mechanism has become a hot spot at home and abroad. Because of the difficulty of sampling large-volume rock mass in the field, the development of indoor artificial rock mass should be solved urgently. Therefore, this paper studies the manufacture technology of high strength artificial rock mass, and solves the problem of hard to get mass rock samples in the field. Firstly, the optimum mix ratio and maintenance system of reactive powder concrete (RPC) are determined by comparison and analysis of sample test. Secondly, by using the numerical simulation method, by studying the distribution law of the thermal stress field in the mass rock mass, the effective measures can be obtained to reduce the internal tensile stress of the mass rock mass. The main research results are as follows: (1) sample test under atmospheric pressure. Seven factors, such as the fineness modulus of quartz sand, the amount of water reducing agent, the ratio of silica fume to fly ash, the ratio of sand to binder, the ratio of water to binder, the amount of compound mineral admixture and the amount of expansive agent, etc. in the design process of RPC concrete mixture were analyzed. The effects of various factors on the fluidity and compressive strength of RPC concrete are obtained. Based on the above two indexes, the optimum mix ratio of RPC concrete under normal pressure curing condition is obtained. (2) specimen test under different curing conditions. By studying the variation of compressive strength and porosity of RPC concrete under four different curing conditions, it is found that the compressive strength of RPC concrete increases more under high temperature and high pressure than that of high temperature curing (the lower the water-binder ratio, the lower the ratio of water to binder). The more obvious the effect is, the more the porosity decreases. This shows that high temperature and high pressure curing can improve the microstructure of RPC concrete, improve the compactness of RPC concrete, and then improve its compressive strength. Based on this, the curing system of high temperature and high pressure is put forward. The RPC concrete with strength up to 200MPa is obtained. (3) the numerical simulation results show that the temperature field distribution of different sizes of rock mass is compared with that of different sizes. The results show that no matter what outer boundary is given to medium volume rock mass, The internal temperature field is close to the uniform temperature field, while the large temperature gradient (.2) exists in the mass rock mass. It is concluded that the external surface of mass rock mass produces a large tensile stress at the stage of cooling. 3) through the comparative analysis of three different ways of lowering temperature and pressure, The results show that the method of decreasing temperature first and then reducing pressure can effectively reduce the maximum tensile stress value of mass rock mass by controlling the rate of lowering temperature and pressure. It is concluded that the temperature stress in the mass rock mass can be effectively reduced by decreasing the cooling and lowering pressure velocity simultaneously. In this paper, the optimum mixture ratio of RPC concrete is given through the experimental study of samples, and the optimal curing system is put forward. The optimal path of cooling and reducing pressure is obtained by numerical simulation. It is of guiding significance for the manufacture of high strength artificial rock mass without macroscopical defects in large volume and provides a prerequisite for the laboratory to carry out the research of mechanical rock breakage.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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