發(fā)布時間：2018-07-05 19:30

  本文選題：熱物理性質(zhì) + 熱破壞��； 參考：《西安科技大學(xué)》2016年碩士論文

【摘要】：煤田火區(qū)的燃燒造成我國環(huán)境的污染、地質(zhì)塌陷、資源浪費和生態(tài)系統(tǒng)破壞。煤巖體的熱物理性參數(shù)和熱破壞特性決定著煤田火的時空發(fā)展演化。為了研究烏達煤田火區(qū)的煤巖體熱物理性參數(shù)和熱破壞特性,論文運用實驗、理論分析和數(shù)值模擬相結(jié)合的方法對火區(qū)的花崗巖、砂巖和煤樣分別進行研究,并且分析了其特征和機理。運用激光閃光LFA457裝置,分析了煤和巖樣的熱物理特性。同溫度,煤樣的熱擴散系數(shù)和導(dǎo)熱系數(shù)隨著揮發(fā)分含量的升高而逐漸降低,然而比熱容呈現(xiàn)出逐漸升高的趨勢,其由物質(zhì)本身決定的熱物理性質(zhì)的變化主要受到溫度影響和發(fā)生的物理化學(xué)復(fù)雜反應(yīng)影響;并且結(jié)合熱重實驗分析煤樣熱物理性質(zhì)變化的原因和特征溫度;花崗巖和砂巖的熱擴散系數(shù)和導(dǎo)熱系數(shù)在相同的溫度下比煤的高,主要是因為煤樣中進行更復(fù)雜的化學(xué)反應(yīng)和煤巖樣所含礦物質(zhì)成分差異造成的;花崗巖和砂巖的熱擴散系數(shù)和導(dǎo)熱系數(shù)隨著溫度升高而降低,而且比熱容隨溫度呈現(xiàn)出增大的趨勢;當(dāng)溫度升高到一定程度時,巖石的導(dǎo)熱系數(shù)和熱擴散系數(shù)基本穩(wěn)定不變。導(dǎo)熱系數(shù)隨溫度的變化情況,對于砂巖而言,主要是由于其自身基本都是晶體結(jié)構(gòu)導(dǎo)致的,然而煤樣主要是由于揮發(fā)分的含量和礦物質(zhì)相變的影響,而花崗巖主要受到變質(zhì)礦物質(zhì)的影響。通過對不同溫度下煤樣和泥巖的CT掃描,運用Drishti軟件對CT掃描圖形進行了三維重建,并且結(jié)合MATLAB對樣品的裂隙和孔隙率進行了計算。25 300°C階段,煤樣的裂隙和孔隙主要是由于熱破壞和內(nèi)部的氣體以及水分蒸發(fā)導(dǎo)致的;300 500°C階段,裂隙的發(fā)展主要是由于內(nèi)部礦物質(zhì)成分的分解和化學(xué)動力學(xué)作用引起的,即熱解導(dǎo)致內(nèi)部大量的烯烴類物質(zhì)釋放。巖樣在低于300°C時,其內(nèi)部孔隙增加,主要是因為巖樣內(nèi)的水分以水蒸氣的形式蒸發(fā)和部分物質(zhì)揮發(fā)引起的;在300 500°C試樣內(nèi)部形成的孔隙和破壞損傷主要是樣品中礦物質(zhì)的相變和熱膨脹不均以及礦物質(zhì)的變質(zhì)造成的。運用RFPA數(shù)值模擬軟件,模擬了巖樣在溫度和壓力耦合作用下的熱破壞,分析研究了其熱破壞的模式和其發(fā)生熱破壞的特征。模擬破壞的模式與CT實驗煤巖裂隙發(fā)展特征基本相同,孔隙、裂隙隨著溫度的升高,其發(fā)展演化逐漸加快,而且其發(fā)展特性主要是沿著原有裂隙的通道繼續(xù)延長和加寬,同時也有部分新生裂隙產(chǎn)生。
[Abstract]:The combustion of coalfield fire area causes environmental pollution, geological collapse, resource waste and ecosystem destruction in China. The thermal physical parameters and thermal failure characteristics of coal and rock mass determine the development and evolution of coal fire in time and space. In order to study the thermal physical parameters and thermal failure characteristics of coal and rock mass in the Wuda coal field, this paper studies the granite, sandstone and coal samples in the fire area by means of experiments, theoretical analysis and numerical simulation. Its characteristics and mechanism are analyzed. The thermal physical properties of coal and rock samples are analyzed by using laser flash LFA457 device. At the same temperature, the thermal diffusivity and thermal conductivity of coal samples decrease with the increase of volatile matter content, but the specific heat capacity increases gradually. The changes of the thermo-physical properties determined by the matter itself are mainly affected by the temperature and the complex physicochemical reactions, and the causes and characteristic temperatures of the changes of the thermo-physical properties of coal samples are analyzed by thermogravimetric experiments. The thermal diffusivity and thermal conductivity of granite and sandstone are higher than that of coal at the same temperature, mainly due to the more complex chemical reaction in coal samples and the difference of mineral composition in coal and rock samples. The thermal diffusivity and thermal conductivity of granite and sandstone decrease with the increase of temperature, and the specific heat capacity increases with temperature, and the thermal conductivity and thermal diffusivity of rock remain stable when the temperature increases to a certain extent. The variation of thermal conductivity with temperature is mainly due to the crystal structure of sandstone itself, but the coal sample is mainly due to the content of volatile matter and the effect of mineral phase transition. Granite is mainly influenced by metamorphic minerals. Through CT scanning of coal samples and mudstones at different temperatures, 3D reconstruction of CT scanning patterns was carried out by using Drishti software, and the fracture and porosity of samples were calculated with MATLAB. The fractures and pores of coal samples are mainly caused by thermal failure and internal gas and water evaporation in the 500 擄C stage. The development of the fractures is mainly caused by the decomposition of the internal mineral components and the chemical kinetics. Pyrolysis results in the release of a large amount of olefins. When the rock sample is below 300 擄C, the internal porosity increases mainly because the moisture in the rock sample evaporates in the form of water vapor and some matter volatilizes. The porosity and damage formed in the sample of 300 ~ 500 擄C are mainly caused by the phase transition and uneven thermal expansion of the minerals in the sample and the metamorphism of the minerals. The numerical simulation software RFPA is used to simulate the thermal failure of rock samples under the coupled action of temperature and pressure. The mode of thermal failure and the characteristics of thermal failure of rock samples are analyzed and studied. The model of simulated failure is basically the same as that of CT experimental coal and rock fractures. With the increase of temperature, the development and evolution of fractures are gradually accelerated, and the development characteristics of these fractures are mainly extended and widened along the original fissure channels. At the same time, there are some new fissures.
【學(xué)位授予單位】：西安科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TD752

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本文編號：2101483