本文選題：“三軟”煤層　切入點：物理相似模擬　出處：《西安科技大學》2017年碩士論文

【摘要】：隨著機械化采掘工藝的推廣應用,在高效的現(xiàn)代綜合機械化采煤工藝在提高產(chǎn)量和推進速度的同時,礦井瓦斯涌出嚴重制約了礦井高產(chǎn)、快速采煤,很大程度上制約了我國煤炭工業(yè)的發(fā)展。為解決“三軟”煤層工程背景下采場瓦斯涌出,研究“三軟”煤層采動裂隙場、瓦斯流動場規(guī)律,是卸壓瓦斯治理充足的理論依據(jù)。本文通過對主采煤層瓦斯基礎參數(shù)進行了測定,煤層瓦斯流量衰減系數(shù)為β=0.2269296,遠大于難以抽放臨界值0.05(0.003～0.05 d-1),試驗礦井5#煤層屬瓦斯難抽放煤層;試驗工作面煤層瓦斯放散初速度在7.05～11.0之間,臨界值10.0在此區(qū)間之內(nèi);煤體孔隙率為11.63;煤層堅固性系數(shù)為0.5411;煤層平均瓦斯含量為3.0678 m3/t,采用分源預測法預測得工作面相對瓦斯涌出量為2.288 m3/t,工作面按日產(chǎn)量按7000 t/d計算,則工作面絕對瓦斯涌出量為11.122 m3/min。采用物理相似模擬實驗和UDEC數(shù)值模擬,分析了煤層開采后采場覆巖破斷規(guī)律、裂隙產(chǎn)生的發(fā)展、時空演化規(guī)律和分布形態(tài)以及卸壓范圍與特征。采場巖石垮落結(jié)果及巖層垮落位移云圖表明:工作面周期來壓平均步距為8 m,在工作面采場發(fā)生第七次周期來壓后,主關(guān)鍵層破斷,裂隙閉合,地表下沉形成盆地,采空區(qū)被逐漸完全壓實,采空區(qū)覆巖在采動過程中基本趨于穩(wěn)定狀態(tài)。距離煤層底板17～29m破斷穿層裂隙較為發(fā)育,離層裂隙范圍在110 m以下,在95～110m范圍內(nèi),形成離層的覆巖僅發(fā)生彎曲下沉,未發(fā)生斷裂破壞。工作面冒落帶最大高度為8～16m,裂隙帶高度為45～65 m,冒落帶區(qū)域內(nèi)巖體塊狀破碎充分,穿層裂隙發(fā)育。根據(jù)工程概況,結(jié)合物理相似模擬實驗和UDEC數(shù)值模擬結(jié)果,在模型假設基礎上建立了基于覆巖運移規(guī)律的三維梯形ANSYS FLUENT物理模型,通過對模型邊界條件進行設定,對采場不采取任何措施時進行數(shù)值運算,采場最大瓦斯?jié)舛冗_到53.10%。通過對高位鉆孔直徑分別0.073 m、0.089 m、0.094m、0.113 m和0.153 m時,結(jié)合不同高位抽采直徑下采場最大瓦斯?jié)舛扰c鉆孔直徑關(guān)系圖可以看出圖中采場瓦斯最大濃度與鉆孔直徑基本呈負相關(guān),相關(guān)系數(shù)為0.9115。在鉆孔直徑為0.153 m時,通過對高位鉆孔抽采負壓分別為10kpa、15kpa、20kpa、25kpa和30kpa時,采場瓦斯運移進行數(shù)值解算,當抽采負壓為30 kpa時,采場最大瓦斯?jié)舛葹?4.06%,從云圖中可以看出瓦斯抽采效果非常顯著,上隅角處瓦斯明顯處于控制之中。工作面現(xiàn)場回風巷已布置高位鉆場12個,高位鉆孔72個,累計施工鉆孔進尺為4860 m,抽放管道內(nèi)瓦斯?jié)舛葹?%～42%,抽放瓦斯純量為1.29～9m3/min,卸壓瓦斯抽采總量為45.82萬m3,有效地降低了工作面回采期間瓦斯?jié)舛?說明了卸壓瓦斯高位鉆孔抽采參數(shù)較為合理,達到了預期的效果,為工作面安全生產(chǎn)提供了保證,同時也驗證了研究方法的科學性和研究結(jié)論的正確性。
[Abstract]:With the popularization and application of mechanized mining technology, the high efficient modern comprehensive mechanized coal mining technology not only increases the output and the speed of propulsion, but also restricts the mine gas emission seriously, which restricts the high yield and fast mining of coal.To a large extent, restricted the development of China's coal industry.In order to solve the problem of gas emission in stope under the background of "three soft" coal seam engineering, it is theoretical basis to study the law of gas flow field in mining crack field and gas flow field of "three soft" coal seam.In this paper, the gas basic parameters of main coal seam are measured. The attenuation coefficient of gas flow in coal seam is 尾 _ (0.2269296), which is far larger than the critical value of 0.05 ~ 0.003 ~ (0.05) d ~ (-1) in difficult drainage. The coal seam in test mine belongs to difficult to drain coal seam.The initial velocity of coal seam gas emission is between 7.05 and 11.0, and the critical value is 10.0.The porosity of coal body is 11.63, the coefficient of coal seam firmness is 0.5411, the average gas content of coal seam is 3.0678 m3 / t, the relative gas emission of working face is 2.288 m3 / t, calculated by daily output of 7000 t / d, the absolute gas emission of working face is 11.122 m3 / min.By using the physical similarity simulation experiment and UDEC numerical simulation, this paper analyzes the overburden rock fracture law, the development of fracture, the space-time evolution law and distribution form, and the pressure relief range and characteristics after coal seam mining.The result of stope rock collapse and the cloud map of rock collapse displacement show that the average step distance of working face periodic pressure is 8 m. After the seventh periodic pressure occurs in the working face, the main key layer breaks down, the fissure closes, and the surface subsidence forms a basin.The goaf is gradually compacted completely, and the overburden of the goaf tends to be stable in the process of mining.The fracture of breaking through layer of 1729 m in distance coal seam floor is relatively developed, the fracture range of separated layer is less than 110 m, in the range of 95 ~ 110m, the overburden that formed the separated layer only bends and sinks, but does not have fracture damage.The maximum height of the caving zone is 816 m and the height of the fracture zone is 45 ~ 65 m. The rock mass in the caving zone is well broken and the fracture in the stratum is developed.According to the general situation of engineering, combined with the results of physical similarity simulation experiment and UDEC numerical simulation, a three-dimensional trapezoidal ANSYS FLUENT physical model based on overburden migration law is established on the basis of model hypothesis. The boundary conditions of the model are set up.The maximum gas concentration of the stope is 53.10 when no measures are taken.The correlation coefficient is 0.9115.When the diameter of the borehole is 0.153 m, the gas migration in the stope is calculated numerically when the negative pressure of the high borehole is 10 kpa-15kpa-20kpa-25kpa and 30kpa, respectively, and the negative pressure is 30 kpa.The maximum gas concentration in the stope is 14.06. It can be seen from the cloud map that the effect of gas drainage is very remarkable and the gas in the upper corner is obviously under control.There are 12 high drilling fields and 72 high drilling holes in the return air roadways in the working face.It is shown that the parameters of high pressure relief gas drilling are reasonable and the expected effect is achieved, which provides a guarantee for the safe production of the working face. At the same time, it also verifies the scientific nature of the research method and the correctness of the research conclusion.
【學位授予單位】：西安科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD712

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