本文選題：含瓦斯煤巖　切入點(diǎn)：采動(dòng)　出處：《重慶大學(xué)》2014年博士論文

【摘要】：隨著煤礦開采深度的增加，地應(yīng)力、瓦斯壓力增大，煤層的滲透性降低，瓦斯災(zāi)害事故頻繁發(fā)生。由于采動(dòng)的影響，煤巖應(yīng)力發(fā)生重新分布，經(jīng)歷了加載和卸載共同作用的復(fù)雜應(yīng)力途徑。以往多采用常規(guī)的加載方式對(duì)煤巖的力學(xué)和滲透特性進(jìn)行研究，這與實(shí)際情況有較大的差異。為此，本文采用試驗(yàn)研究、理論分析、數(shù)值模擬等相結(jié)合的方法，利用自行研制的“含瓦斯煤熱流固耦合三軸伺服滲流實(shí)驗(yàn)裝置”，對(duì)常規(guī)加載條件和不同加卸載條件下含瓦斯煤的力學(xué)特性和滲透規(guī)律進(jìn)行試驗(yàn)研究，揭示不同加卸載條件下含瓦斯煤的變形模量、泊松比、強(qiáng)度以及滲透特性等變化規(guī)律；研制了“多場(chǎng)多相耦合下多孔介質(zhì)壓裂-滲流實(shí)驗(yàn)系統(tǒng)”并進(jìn)行了煤巖不同開采條件下力學(xué)特性及滲透率變化規(guī)律的試驗(yàn)研究；利用“多場(chǎng)耦合煤礦動(dòng)力災(zāi)害大型模擬試驗(yàn)系統(tǒng)”對(duì)真三軸應(yīng)力狀態(tài)下大尺度煤巖在常規(guī)加載及不同開采條件下的力學(xué)及滲流特性進(jìn)行研究；建立了常規(guī)加載及不同加卸載條件下含瓦斯煤的有效應(yīng)力計(jì)算公式及滲透率與有效應(yīng)力關(guān)系的公式；采用數(shù)值計(jì)算的方法，對(duì)煤層瓦斯在采動(dòng)影響條件下工作面前方和采空區(qū)上方采動(dòng)裂隙場(chǎng)中瓦斯運(yùn)移規(guī)律進(jìn)行數(shù)值模擬分析。本文主要研究成果如下： ①采動(dòng)應(yīng)力影響下煤巖的應(yīng)力路徑表現(xiàn)為軸向應(yīng)力加載和圍壓卸載的共同作用。含瓦斯煤的承載強(qiáng)度與不同的加卸載條件有如下關(guān)系：加卸載煤樣的承載強(qiáng)度隨初始軸力的升高呈指數(shù)關(guān)系降低，隨圍壓卸載速度的增加呈指數(shù)函數(shù)關(guān)系降低，，隨初始圍壓的升高呈指數(shù)關(guān)系降低，隨瓦斯壓力的升高呈線性關(guān)系降低。變形模量隨軸向應(yīng)變的增加均呈先迅速減小然后緩慢減小直至破壞后保持基本穩(wěn)定的趨勢(shì)；不同加卸載條件下含瓦斯煤的泊松比均表現(xiàn)出隨著軸向應(yīng)變的增加先逐漸減小后迅速增加最后基本保持穩(wěn)定。 ②常規(guī)加載與加卸載條件下煤樣滲透率與應(yīng)變的關(guān)系在屈服前規(guī)律有所不同，屈服前常規(guī)加載滲透率與應(yīng)變呈二次曲線關(guān)系減�。欢有遁d滲透率隨應(yīng)變首先呈線性關(guān)系增加然后呈二次曲線關(guān)系減小。煤樣屈服后兩種條件下滲透率與應(yīng)變的關(guān)系規(guī)律基本相同，即呈指數(shù)關(guān)系增大，且與軸向應(yīng)變呈正指數(shù)關(guān)系增大，與徑向應(yīng)變和體積應(yīng)變呈負(fù)指數(shù)關(guān)系增大。 ③三軸加載及加卸載條件下含瓦斯煤變形破壞過程中彈性應(yīng)變能的變化趨勢(shì)與軸向應(yīng)力的變化趨勢(shì)相對(duì)應(yīng)。圍壓卸載過程中，含瓦斯煤?jiǎn)卧纳⒛茈S著卸載位置軸向壓力的增加而增加，且其占單元總能量增加量的比例增大。 ④自行研制了“多場(chǎng)多相耦合下多孔介質(zhì)壓裂 滲流實(shí)驗(yàn)系統(tǒng)”，并利用該系統(tǒng)進(jìn)行了常規(guī)加載及不同開采條件下煤巖的試驗(yàn)研究。常規(guī)加載條件含瓦斯煤的峰值強(qiáng)度遠(yuǎn)遠(yuǎn)大于開采條件下含瓦斯煤的峰值強(qiáng)度，無煤柱開采、放頂煤開采、保護(hù)層開采三種開采條件下含瓦斯煤及不含瓦斯煤的峰值強(qiáng)度依次降低。 ⑤真三軸應(yīng)力狀態(tài)下大尺度煤巖滲透率變化曲線與體積應(yīng)變變化曲線有較好的對(duì)應(yīng)關(guān)系，滲透率均首先隨著體積應(yīng)變的增加而減小，然后隨著體積應(yīng)變的減小而有不同程度的增加。無煤柱開采、放頂煤開采、保護(hù)層開采煤巖滲透率在減小階段其減小量依次減小，滲透率在增加階段其增加量逐漸增加。一定瓦斯壓力范圍內(nèi)，瓦斯壓力越大，大尺度煤巖滲透率減小量越小，滲透率增加量增加。 ⑥考慮瓦斯力學(xué)作用和瓦斯吸附作用兩個(gè)方面對(duì)有效應(yīng)力系數(shù)的影響，建立了單調(diào)加載及加卸載條件下原煤的有效應(yīng)力計(jì)算公式及滲透率與有效應(yīng)力關(guān)系的公式。含瓦斯煤的有效應(yīng)力系數(shù)隨著圍壓的增加而線性減小，含瓦斯煤的有效應(yīng)力系數(shù)隨著瓦斯壓力的增加而線性增加，加卸載條件下的有效應(yīng)力系數(shù)小于單調(diào)加載條件下的有效應(yīng)力系數(shù)。 ⑦基于采動(dòng)影響下煤層瓦斯運(yùn)移的數(shù)學(xué)模型，利用UDEC軟件模擬開采過程中裂隙場(chǎng)的演化形態(tài)，隨著工作面的不斷推進(jìn)，采空區(qū)上方上覆巖層形成采動(dòng)裂隙梯形臺(tái)，并進(jìn)行了煤層瓦斯在采動(dòng)裂隙場(chǎng)中瓦斯運(yùn)移動(dòng)態(tài)演化規(guī)律的COMSOL數(shù)值模擬研究，采動(dòng)裂隙場(chǎng)中的離層裂隙和豎向破斷裂隙具有瓦斯流動(dòng)導(dǎo)向性。 ⑧利用COMSOL軟件模擬分析工作面前方三種開采條件下煤層瓦斯?jié)B透率變化規(guī)律與支承壓力分布規(guī)律，兩者有較好的對(duì)應(yīng)關(guān)系。隨著工作面推進(jìn)距離的增加，三種開采條件下煤層支承壓力對(duì)應(yīng)的應(yīng)力集中系數(shù)增加，且增加的趨勢(shì)逐漸變緩；當(dāng)工作面推進(jìn)距離相同時(shí)，無煤柱開采、放頂煤開采、保護(hù)層開采三種開采條件下應(yīng)力集中系數(shù)依次降低。
[Abstract]:With the increase of the mining depth of coal mine , the stress and gas pressure increase , the permeability of the coal seam decreases , and the gas disaster accidents happen frequently . Due to the influence of mining , the coal - rock stress is redistributed . The mechanical properties and permeability of the coal - bearing coal under different loading conditions are studied , and the variation law of deformation modulus , Poisson ' s ratio , strength and permeability of gas - containing coal under different loading conditions are revealed .
In this paper , a multi - field multi - phase coupled porous medium fracturing - seepage experimental system was developed and the mechanical properties and permeability variation law of different mining conditions were studied .
The mechanical and seepage characteristics of large scale coal rock under normal loading and different mining conditions are studied by using the " Multi - field Coupled Coal Mine Dynamic Disaster Large Scale Simulation Test System " .
The formulas for calculating the effective stress and the relationship between permeability and effective stress of gas - containing coal under normal loading and different loading conditions are established .
The numerical simulation of the gas migration law of coal seam gas under the influence of mining operation is carried out by numerical simulation . The main research results are as follows :

The stress path of coal rock under the influence of mining stress is the joint action of axial stress loading and confining pressure unloading . The bearing strength of coal containing gas decreases exponentially with the increase of initial axial force .
The Poisson ' s ratio of gas - containing coal under different loading conditions shows that the increase of axial strain increases first and then increases rapidly .

( 2 ) The relationship between the coal sample permeability and strain under normal loading and loading conditions is different before the yield , and the relationship between the conventional loading permeability and strain before yielding is reduced ;
The relationship between permeability and strain is basically the same , that is , exponential relationship increases , and the relationship with axial strain increases with negative exponential relationship with radial strain and volumetric strain .

( 3 ) The change tendency of elastic strain energy in the process of triaxial loading and loading and unloading is corresponding to the changing tendency of axial stress . During confining pressure unloading , the dissipation energy of gas - containing coal unit increases with increasing axial pressure of unloading position , and the proportion of total energy increment of the unit increases .

鈶ｈ嚜琛岀爺鍒朵簡(jiǎn)鈥滃鍦哄鐩歌

本文編號(hào)：1691732