本文選題：煤巖體　切入點(diǎn)：煤體破壞規(guī)律　出處：《西安科技大學(xué)》2017年碩士論文

【摘要】：我國(guó)煤田火災(zāi)嚴(yán)重,嚴(yán)重的破壞了煤炭資源和生態(tài)環(huán)境。煤層裂隙演化與煤田火區(qū)的發(fā)展互相影響,因此,研究煤巖體裂隙發(fā)展變化規(guī)律及其影響因素,揭示煤田火區(qū)燃燒機(jī)理,對(duì)于控制煤田火區(qū)的發(fā)展具有重要的意義。本文研究溫度和壓力作用下煤體破壞裂隙的演化規(guī)律,以新疆硫磺溝火區(qū)的煤樣為研究對(duì)象,研究了煤體裂隙發(fā)生發(fā)育的機(jī)理、特征及其變化過(guò)程。理論分析了溫度-壓力作用下的煤體裂隙形成過(guò)程,構(gòu)建了煤體溫-壓耦合數(shù)學(xué)模型,實(shí)驗(yàn)測(cè)試煤體的熱力學(xué)參數(shù),并運(yùn)用RFPA數(shù)值軟件模擬了煤樣在溫度和壓力耦合作用下的破壞過(guò)程。設(shè)定的壓力值越接近煤樣峰值強(qiáng)度,升溫時(shí),裂隙變化就越明顯。壓力較小時(shí),在140℃左右,煤樣的破壞速率最大。壓力較大時(shí),在80℃左右,煤樣的破壞速率最大。采用MTS-880/25t電液伺服試驗(yàn)系統(tǒng)、聲發(fā)射儀、工業(yè)CT掃描系統(tǒng)測(cè)試了四組煤樣(每組4個(gè)試樣)經(jīng)常溫、80℃、140℃、200℃下恒溫處理后的力學(xué)特性及裂隙發(fā)育情況。溫度越高,全應(yīng)力-應(yīng)變曲線(xiàn)越離散;煤樣峰值強(qiáng)度、彈性模量隨著溫度先升高后降低,在140℃達(dá)到最大值;煤樣有損傷時(shí),強(qiáng)度會(huì)降低。峰值前聲發(fā)射信號(hào)最強(qiáng),溫度越高,聲發(fā)射接收的信號(hào)越少;聲發(fā)射峰值的數(shù)量隨著溫度升高先增加后降低、能量則先降低后升高,80℃是其突變溫度點(diǎn)。溫度升高,煤樣呈現(xiàn)破壞裂隙減少而破壞能增加的趨勢(shì)。每組試件經(jīng)無(wú)壓、50kN、80kN單軸恒壓處理后進(jìn)行CT掃描。結(jié)果顯示:無(wú)壓時(shí)隨著溫度升高裂隙長(zhǎng)度和寬度增加,在140℃時(shí)達(dá)到最大值,約為20mm、0.6mm。同一溫度下加壓時(shí),裂隙的發(fā)育在強(qiáng)度峰值前最明顯。壓力的增加會(huì)使同溫度下煤體的破壞率增加,加速煤體的破裂。采用耐馳LFA457裝置對(duì)力學(xué)實(shí)驗(yàn)處理后的煤樣進(jìn)行30-200℃溫度范圍內(nèi)熱物理參數(shù)的測(cè)定。發(fā)現(xiàn)隨著溫度升高熱擴(kuò)散系數(shù)而降低,導(dǎo)熱系數(shù)和比熱容增大,140℃的試件達(dá)到最大值。溫度越高,熱物性變化越不明顯。綜合實(shí)驗(yàn)測(cè)試和數(shù)值模擬結(jié)果,確定140 ℃是其裂隙發(fā)育的突變溫度點(diǎn)。
[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，

本文編號(hào)：1721734