Experimental investigation on the reformation and strength weakening of hard limestone by acidizing
Experimental investigation on the reformation and strength weakening of hard limestone by acidizing
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DOI：
10.1016/j.ijmst.2022.08.008
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发表时间：
2022-09-01
影响因子：
11.8
通讯作者：
Xing, Yuekun
中科院分区：
文献类型：
--
作者：
Huang, Bingxiang;Hou, Mingxiao;Xing, Yuekun
煤矿坚硬顶板可引发矿压灾害、瓦斯爆炸等衍生灾害。对于整体性好、硬度极高的石灰岩顶板，坍塌难度大，常规顶板控制方法效果有限。酸化改造是基于酸岩反应弱化顶板岩层强度的有效途径。通过石灰岩酸化实验，验证了岩石强度损伤规律和酸化反应特征。此外，还分析了酸性作用下石灰岩的强度退化机理。结果表明，石灰石具有明显的酸腐蚀特征，在酸腐蚀作用下，大量的矿物颗粒产生空洞，内部形成较多的缺陷。酸岩反应早期最强烈，然后逐渐达到动态平衡，石灰岩的酸蚀率为4.24%(10%盐酸，360分钟)。坚硬的石灰岩在酸化后受到破坏。此外，在荷载作用下，内部裂纹可以快速萌生和不稳定扩展，使岩石破坏所需的应变降低33.33%。破坏形态更加复杂，单轴抗压强度和弹性模量分别下降了52.42%和34.44%。酸化后坚硬顶板的强度弱化是由于酸性作用下岩石晶体的腐蚀产生晶间开裂等缺陷，在外力作用下加速了内部裂纹的萌生和扩展。宏观上，酸化通过改变顶板结构导致岩石力学性质恶化。本研究证实了酸化改造方法控制坚硬顶板的可行性。(C)爱思唯尔公司代表中国矿业大学出版的《2022年》。这是CC BY-NC-ND License(http://creativecommons.org/licenses/by-nc-nd/4.0/).下的一篇开放获取文章
Several derivative disasters such as ground pressure disasters and methane explosions can be caused by the hard roof in coal mines. For limestone roofs with fine integrity and extreme hardness, collapse is dif-ficult and the effect of conventional roof control methods is limited. Acidizing reformation is an effective way to weaken the strength of roof strata based on acid-rock reaction. In this study, the rock strength damage law and acid reaction characteristics were tested by the limestone acidification experiment. Besides, the strength degradation mechanism of limestone under the acidity effect was analyzed. The results show that the acid corrosion characteristics of limestone are obvious, as numerous mineral grains generate voids under the effects of acid corrosion, and more defects are formed inside. The acid-rock reac-tion is the most intense at the early stage and then gradually reaches dynamic equilibrium, and the acid corrosion rate of limestone is 4.24% (10% HCl, 360 min). The hard limestone is damaged after acidification. Furthermore, the internal cracks can be induced to rapid initiation and unstable propagation under load, which reduces the strain required for rock failure by 33.33%. The failure morphology is more complicated, and the uniaxial compressive strength and elastic modulus decrease by 52.42% and 34.44% respectively. The strength weakening of hard roof after acidification is due to the defects such as intergranular cracking caused by the corrosion of rock crystals under acidity effect, which accelerate the initiation and propaga-tion of internal cracks with external force. Macroscopically, acidification induced the deterioration of rock mechanical properties by reforming the roof structure. The feasibility of acidizing reformation method to control hard roof is confirmed in this study.(c) 2022 Published by Elsevier B.V. on behalf of China University of Mining & Technology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).