MHC耦合腐蚀下灰岩的损伤试验研究及机理分析

发布时间：2018-09-11 08:04

【摘要】：近年来,龙门石窟岩体受渗透水流和山体上的腐殖质、酸雨、酸雾等化学腐蚀作用的影响越来越大,应力(M)-水流(H)-化学(C)的耦合作用更加速了石窟岩体的腐蚀损伤,进一步消弱了岩体的物理力学性质,对石窟岩体的长期稳定性产生威胁。本文根据龙门石窟区的应力、水流、化学等影响因素,开展了龙门石窟新鲜灰岩在MHC耦合腐蚀下的物理力学试验研究,分析了物理力学参数的损伤时效特征和腐蚀损伤机理,研究成果将为龙门石窟的保护工作提供一定的理论依据,具有重要的实际工程价值。主要研究工作和成果如下:1.开展了MC耦合作用对龙门石窟新鲜灰岩物理力学行为的时间效应研究,进行了MC耦合作用不同时间下灰岩的质量、弹性波速、单轴压缩强度和水溶液的pH值的测试,并对新鲜、风化灰岩的试验结果对比分析。结果表明:质量的增加主要是由于水分的吸收所引起的,受化学溶液性质的影响不大,不同水溶液中30天内就能达到稳定。风化灰岩比新鲜灰岩的弹性波速到达最高点和最低点的时间早,波速变化频繁,腐蚀前后的波速变化量大。无论风化还是新鲜岩样,pH值达到稳定所需的时间,龙门水最短,Na2SO4溶液最长,其中浸泡风化、新鲜岩样的龙门水达到稳定的时间分别为2h、10h,Na2SO4溶液则分别为20d、35d。在相同水溶液中,风化灰岩比新鲜灰岩强度降低幅度更大,水溶液作用时间越长强度降低越明显。2.开展了MHC耦合作用对龙门石窟新鲜灰岩物理力学行为的时间效应研究,进行了MHC耦合作用不同时间下灰岩的质量、弹性波速、单轴压缩强度和水溶液的pH值的测试,并进行了MC与MHC耦合作用下新鲜灰岩试验结果的对比分析。结果表明:MHC耦合作用下质量达到稳定的时间比MC更长,质量减小幅度变大,弹性波速随时间的变化周期变短,水溶液最终稳定的pH值变大,pH值到达稳定的时间变短。在相同浓度和pH值下,NaCl溶液使强度降低大;在相同浓度和化学成分下,pH越小使强度降低越大;在相同pH值和化学成分下,浓度越大使强度降低越大。MHC耦合腐蚀使强度降低更大,随着腐蚀时间的增加,强度降低幅度越大。3.建立了MHC耦合作用下龙门石窟灰岩的腐蚀损伤模型,并与试验结果进行对比,结果表明,该模型与试验吻合较好。
[Abstract]:In recent years, the rock mass of Longmen Grottoes has been affected more and more by chemical corrosion such as humus, acid rain, acid fog and so on. The coupling of stress (M), water (H) and chemical (C) accelerates the corrosion damage of grotto rock mass. It further weakens the physical and mechanical properties of the rock mass and threatens the long-term stability of the rock mass. According to the influence factors of stress, water flow and chemistry in Longmen Grottoes, the physical and mechanical tests of fresh limestone in Longmen Grottoes under MHC coupling corrosion are carried out, and the damage aging characteristics and corrosion damage mechanism of physical and mechanical parameters are analyzed. The research results will provide some theoretical basis for the protection of Longmen Grottoes and have important practical engineering value. The main research work and results are as follows: 1. The time effect of MC coupling on the physical and mechanical behavior of fresh limestone in Longmen Grottoes has been studied. The mass, elastic wave velocity, uniaxial compression strength and pH value of aqueous solution of limestone under MC coupling have been measured. Comparative analysis of test results of weathered limestone. The results show that the increase of mass is mainly caused by the absorption of water, but is not affected by the properties of chemical solution, and it can be stabilized in different aqueous solutions within 30 days. The elastic wave velocities of weathered limestone reach the highest and lowest points earlier than those of fresh limestone. The wave velocities change frequently and the changes of wave velocities before and after corrosion are larger. No matter when the pH value of weathered or fresh rock samples reaches the stable time, the shortest Na _ 2SO _ 4 solution in Longmen water is the longest. The time of soaking and weathering is 20 d ~ (35) d, respectively, when the fresh rock sample reaches stability time of 2 h ~ 10 h ~ (-1) and Na ~ (2SO _ 4) _ 4 solution, respectively. In the same aqueous solution, the strength of weathered limestone decreases more than that of fresh limestone, and the longer the action time of aqueous solution is, the more obviously the strength of weathered limestone decreases. The time effect of MHC coupling on the physical and mechanical behavior of fresh limestone in Longmen Grottoes is studied. The mass, elastic wave velocity, uniaxial compression strength and pH value of aqueous solution of limestone under MHC coupling are measured. The results of fresh limestone test under the coupling of MC and MHC are compared and analyzed. The results show that the time of mass stabilization is longer than that of MC, the amplitude of mass decrease is larger, the period of elastic wave velocity changes with time is shorter, and the pH value of final stability of aqueous solution is larger than that of MC, and the time when pH value reaches stability becomes shorter. At the same concentration and pH value, the strength of the solution decreased greatly; the smaller the pH value and the chemical composition, the greater the strength of the solution; the greater the concentration of pH and the chemical composition, the greater the strength of the solution. With the increase of corrosion time, the intensity decreases more. 3. The corrosion damage model of limestone in Longmen Grottoes under the action of MHC coupling is established and compared with the experimental results. The results show that the model is in good agreement with the test.
【学位授予单位】：河南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU45

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