水对煤岩蠕变力学特性影响的试验研究

发布时间：2018-04-19 00:13

本文选题：煤岩 + 蠕变　；参考：《西安科技大学》2017年硕士论文

【摘要】：目前,我国煤炭生产的安全形势仍然十分严峻,煤矿生产事故时有发生。地下采煤时,随着开采时间的增加,煤柱在顶板压力的作用下会发生蠕变现象,进而会使上层顶板失去支撑而坍塌破坏,出现煤矿事故。另一方面,煤岩体的导水性强,且遇水后力学性质发生显著变化,水是影响岩石蠕变性质的一个重要因素。因此,对于地下采煤工程来说,研究不同浸润条件下煤岩蠕变力学特性显得尤为重要。论文针对矿区日益增长的工程需要,以试验研究为基础,借助DNS200型电子万能试验机、SAEU2S声发射系统以及Vic-3D应变测量系统,系统地研究煤岩在不同浸润时间下的蠕变力学特性,为矿区采煤工程建设提供一定的理论基础。从现场取回煤岩岩块,加工成?50mm?100mm的国际标准试件,将试件分为4组,分别在水中浸润0h、48h、96h、144h,并对4组试件分别进行单轴压缩蠕变试验,试验过程中观察并记录煤岩蠕变破坏过程及破坏方式,探讨煤岩蠕变峰值应力、轴向应变随浸润时间的变化规律,分析煤岩蠕变断裂破坏的影响因素。结果表明:煤岩的蠕变破坏一般呈现为劈裂破坏;随着浸润时间的增加,煤岩的蠕变峰值应力逐渐降低,轴向应变呈现增大的趋势。对经历不同浸润时间(0h、48h、96h、144h)后的煤岩试件进行单轴压缩蠕变声发射特性试验。研究煤岩蠕变试验过程与声发射参数之间的对应关系,分析浸润时间对声发射参数(振铃计数、能量、幅度)的影响规律。研究表明:通过分析声发射参数的变化可以很好的描述煤岩试件在蠕变过程中的各个阶段的力学特征。借助Vic-3D应变测量系统为辅助工具,对煤岩单轴压缩试验进行监测,通过散斑的移动得到二维应变,进而得到煤岩表面的应变云图。结果表明:随着浸润时间的增加,煤岩试件的峰值应力与弹性模量逐渐降低,而峰值应变逐渐增大;在煤岩单轴压缩破坏过程中,煤岩试件表面的应变演化云图可以很好的与其破坏过程相对应,试件最终破坏是按照产生裂缝的区域开始断裂。因此认为轴向与横向应变的变化趋势可以直观再现煤岩的细观力学特征,预测其最终破坏形态。
[Abstract]:At present, China's coal production safety situation is still very serious, coal production accidents occur from time to time.In underground coal mining, with the increase of mining time, the coal pillar will creep under the action of roof pressure, which will make the upper roof lose its support and collapse and destroy, resulting in coal mine accident.On the other hand, the water conductivity of coal and rock mass is strong, and the mechanical properties of coal and rock mass change obviously after water treatment. Water is an important factor affecting the creep property of rock.Therefore, for underground coal mining, it is very important to study the creep mechanical properties of coal and rock under different wetting conditions.Aiming at the increasing engineering demand in mining area, based on the experimental research, the creep mechanical properties of coal and rock under different soaking times are systematically studied by means of DNS200 electronic universal testing machine SAEU2S acoustic emission system and Vic-3D strain measurement system.It provides a certain theoretical basis for coal mining engineering construction in mining area.The coal and rock blocks were collected from the site and processed into international standard specimens of 50 mm to 100 mm. The specimens were divided into 4 groups, which were wetted in water for 0 h or 48 h or 96 h or 144 h, respectively, and four groups of specimens were subjected to uniaxial compression creep tests.The creep failure process and failure mode of coal and rock were observed and recorded during the test. The variation of creep peak stress and axial strain with soaking time were discussed and the influencing factors of creep fracture of coal and rock were analyzed.The results show that the creep failure of coal and rock is generally split failure and the creep peak stress of coal and rock decreases gradually and the axial strain increases with the increase of soaking time.The acoustic emission characteristics of uniaxial compression creep of coal and rock specimens after different wetting times were tested at 48h ~ 96h ~ 144h.The relationship between the creep test process of coal and rock and the acoustic emission parameters is studied, and the influence of soaking time on the acoustic emission parameters (ring count, energy, amplitude) is analyzed.The results show that the change of acoustic emission parameters can well describe the mechanical characteristics of coal and rock specimens in each stage of creep process.With the aid of Vic-3D strain measurement system, the uniaxial compression test of coal and rock was monitored, and the strain cloud map of coal and rock surface was obtained through the movement of speckle.The results show that with the increase of soaking time, the peak stress and elastic modulus of coal and rock specimens decrease gradually, while the peak strain increases gradually, and in the process of uniaxial compression of coal and rock,The strain evolution cloud map on the surface of coal and rock specimen can well correspond to the failure process, and the ultimate failure of the specimen is to start the fracture according to the area where the fracture occurred.It is concluded that the variation trend of axial and transverse strain can visualize the meso-mechanical characteristics of coal and rock and predict its ultimate failure form.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD315

【参考文献】