本文選題：水力致裂 + 骨架應(yīng)力��； 參考：《中國礦業(yè)大學(xué)》2017年碩士論文

【摘要】：煤巖體水力致裂技術(shù)已廣泛應(yīng)用于煤炭行業(yè),利用水力致裂技術(shù)防治煤與瓦斯突出以及沖擊礦壓等方面已取得初步成效。目前,水力致裂期間引起煤巖體應(yīng)力的變化規(guī)律還不清楚,對于利用水力致裂技術(shù)進行煤礦動力災(zāi)害防治而引起的應(yīng)力擾動是否會誘導(dǎo)突出和沖擊仍具有爭議。因此,研究煤巖體水力致裂期間及致裂之后的應(yīng)力擾動規(guī)律是一項非常迫切且必要的基礎(chǔ)性研究。本文采用物理模擬實驗、數(shù)值模擬、理論分析和現(xiàn)場分析等方法對煤巖體水力致裂期間及之后的應(yīng)力擾動規(guī)律進行研究。通過在試塊內(nèi)部埋設(shè)骨架應(yīng)力傳感器和孔隙水壓力傳感器,運用大尺寸真三軸水力致裂實驗系統(tǒng)進行了物理模擬實驗,實時監(jiān)控了水力致裂過程中水壓力的動態(tài)變化,監(jiān)測了試塊內(nèi)骨架應(yīng)力的動態(tài)變化,研究了水力致裂過程中裂縫周邊的應(yīng)力及其梯度變化規(guī)律,實驗結(jié)果表明:在三個主應(yīng)力方向上,排量越大,應(yīng)力擾動現(xiàn)象越明顯;距離致裂鉆孔越近,其應(yīng)力擾動現(xiàn)象越明顯;在垂直于主破裂面方向的應(yīng)力擾動最為明顯,其他方向的應(yīng)力擾動相對較小。運用RFPA2D-FLOW數(shù)值模擬軟件對水力致裂的應(yīng)力擾動規(guī)律進行研究,模擬結(jié)果表明:鉆孔開裂前,在鉆孔周圍形成壓應(yīng)力集中,并且隨著鉆孔水壓力的增大,垂直于最小主應(yīng)力方向上的應(yīng)力集中系數(shù)逐漸增大,最大主應(yīng)力方向上的應(yīng)力集中系數(shù)逐漸減小,并且應(yīng)力擾動的影響范圍逐漸增大;鉆孔開裂后,隨著水壓裂縫的張開及擴展,垂直于最小主應(yīng)力方向的應(yīng)力集中系數(shù)及應(yīng)力升高區(qū)的范圍逐漸增大,并且在水壓裂縫尖端形成明顯的拉應(yīng)力集中,使裂尖發(fā)生張拉破壞;距離鉆孔越遠(yuǎn),水壓力對主應(yīng)力的影響越小,同時應(yīng)力梯度的變化也越小。運用彈性力學(xué)、水力學(xué)、滲流力學(xué)及斷裂力學(xué)進行理論分析,分別從鉆孔未注水時、鉆孔注水未開裂時及鉆孔注水開裂后三個階段計算了鉆孔周邊和裂縫周邊應(yīng)力場。結(jié)合燕子山煤礦8403工作面水力致裂現(xiàn)場實測數(shù)據(jù),選取了2個致裂孔數(shù)據(jù)進行分析,結(jié)果表明:在致裂的過程中,在工作面聽見多次頂板破裂聲,說明由于水壓裂縫的產(chǎn)生及擴展使得工作面內(nèi)的應(yīng)力擾動較為明顯,在某個局部形成較大的應(yīng)力集中,使煤巖體處于塑性變形范圍內(nèi),當(dāng)應(yīng)力集中超過煤巖體的塑性極限時,應(yīng)變能釋放,進而煤巖體內(nèi)的應(yīng)力向深部轉(zhuǎn)移。
[Abstract]:Hydraulic fracturing technology of coal and rock mass has been widely used in coal industry. Preliminary results have been obtained in preventing coal and gas outburst and impacting rock pressure by hydraulic fracturing technology.At present, it is not clear how the stress of coal and rock mass changes during hydraulic fracturing, and whether the stress disturbance caused by hydraulic fracturing technology can induce outburst and impact is still controversial.Therefore, it is an urgent and necessary basic study to study the stress disturbance during and after hydraulic fracturing of coal and rock mass.In this paper, physical simulation, numerical simulation, theoretical analysis and field analysis are used to study the stress disturbance during and after hydraulic fracturing of coal and rock mass.By embedding skeleton stress sensor and pore water pressure sensor inside the specimen, the physical simulation experiment was carried out by using the large size true triaxial hydraulic fracturing experimental system, and the dynamic change of water pressure during hydraulic fracturing was monitored in real time.The dynamic change of skeleton stress in the specimen is monitored, and the stress and its gradient change around the crack during hydraulic fracture are studied. The experimental results show that the larger the displacement of the three principal stresses is, the more obvious the stress disturbance is.The closer the borehole is to the fracture, the more obvious the stress disturbance is, the more obvious the stress disturbance is in the direction perpendicular to the main fracture plane, the smaller the stress disturbance is in the other directions.The RFPA2D-FLOW numerical simulation software is used to study the stress disturbance law of hydraulic cracking. The simulation results show that the compressive stress concentration is formed around the borehole before the borehole cracks, and with the increase of the borehole water pressure,The stress concentration factor perpendicular to the direction of the minimum principal stress increases gradually, the stress concentration factor in the direction of the maximum principal stress decreases gradually, and the influence range of stress disturbance increases gradually.The stress concentration factor perpendicular to the direction of the minimum principal stress and the range of the stress increasing zone gradually increase with the opening and expansion of the hydraulic crack, and the tensile stress concentration forms at the tip of the hydraulic crack, which leads to the tensile failure of the crack tip.The farther away from the borehole, the smaller the influence of water pressure on principal stress and the smaller the change of stress gradient.Based on the theoretical analysis of elasticity, hydraulics, seepage mechanics and fracture mechanics, the stress fields around the borehole and around the fracture were calculated from the three stages of the borehole without water injection, the borehole water injection cracking and the drilling water injection cracking.Combined with the measured data of hydraulic cracking in 8403 working face of Yanzishan Coal Mine, the data of two cracked holes are selected for analysis. The results show that: in the process of cracking, the sound of roof cracking is heard many times in the working face.It is shown that the stress disturbance in the working face is obvious due to the production and expansion of the hydraulic crack, and a large stress concentration is formed in a certain area, which makes the coal and rock mass within the plastic deformation range, and when the stress concentration exceeds the plastic limit of the coal and rock mass,The strain energy is released and the stress in the coal and rock is transferred to the deep.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TD712.6

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