温压作用下煤体破坏裂隙演化规律的研究

发布时间：2018-04-08 13:05

  本文选题：煤岩体　切入点：煤体破坏规律　出处：《西安科技大学》2017年硕士论文

【摘要】：我国煤田火灾严重,严重的破坏了煤炭资源和生态环境。煤层裂隙演化与煤田火区的发展互相影响,因此,研究煤岩体裂隙发展变化规律及其影响因素,揭示煤田火区燃烧机理,对于控制煤田火区的发展具有重要的意义。本文研究温度和压力作用下煤体破坏裂隙的演化规律,以新疆硫磺沟火区的煤样为研究对象,研究了煤体裂隙发生发育的机理、特征及其变化过程。理论分析了温度-压力作用下的煤体裂隙形成过程,构建了煤体温-压耦合数学模型,实验测试煤体的热力学参数,并运用RFPA数值软件模拟了煤样在温度和压力耦合作用下的破坏过程。设定的压力值越接近煤样峰值强度,升温时,裂隙变化就越明显。压力较小时,在140℃左右,煤样的破坏速率最大。压力较大时,在80℃左右,煤样的破坏速率最大。采用MTS-880/25t电液伺服试验系统、声发射仪、工业CT扫描系统测试了四组煤样(每组4个试样)经常温、80℃、140℃、200℃下恒温处理后的力学特性及裂隙发育情况。温度越高,全应力-应变曲线越离散;煤样峰值强度、弹性模量随着温度先升高后降低,在140℃达到最大值;煤样有损伤时,强度会降低。峰值前声发射信号最强,温度越高,声发射接收的信号越少;声发射峰值的数量随着温度升高先增加后降低、能量则先降低后升高,80℃是其突变温度点。温度升高,煤样呈现破坏裂隙减少而破坏能增加的趋势。每组试件经无压、50kN、80kN单轴恒压处理后进行CT扫描。结果显示:无压时随着温度升高裂隙长度和宽度增加,在140℃时达到最大值,约为20mm、0.6mm。同一温度下加压时,裂隙的发育在强度峰值前最明显。压力的增加会使同温度下煤体的破坏率增加,加速煤体的破裂。采用耐驰LFA457装置对力学实验处理后的煤样进行30-200℃温度范围内热物理参数的测定。发现随着温度升高热扩散系数而降低,导热系数和比热容增大,140℃的试件达到最大值。温度越高,热物性变化越不明显。综合实验测试和数值模拟结果,确定140 ℃是其裂隙发育的突变温度点。
[Abstract]:The coal fires in our country are serious, which seriously destroy the coal resources and ecological environment.The evolution of coal seam fissures and the development of coalfield fire area influence each other. Therefore, it is of great significance to study the law of coal and rock mass fracture development and its influencing factors, and to reveal the combustion mechanism of coal field fire area for controlling the development of coal field fire area.In this paper, the evolution law of coal fracture under the action of temperature and pressure is studied. The mechanism, characteristics and changing process of coal fracture development are studied with coal samples in the brimstone ditch fire area of Xinjiang as the research object.The formation process of coal fracture under the action of temperature and pressure is analyzed theoretically, and the coupled mathematical model of temperature and pressure of coal is constructed, and the thermodynamic parameters of coal body are tested experimentally.The failure process of coal samples under the coupling of temperature and pressure is simulated by RFPA software.The closer the pressure value is to the peak strength of the coal sample, the more obvious the fracture change is when the temperature rises.When the pressure is small, the rate of destruction of coal sample is the highest at about 140 鈩，

本文编号：1721734