本文關(guān)鍵詞： 裂隙巖體 荷載水平 滲透特性 水力梯度 導(dǎo)水系數(shù) 非線性流動特征　出處：《中國礦業(yè)大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：由于地質(zhì)運動和人為擾動,天然巖體內(nèi)部通常賦存裂隙或裂隙網(wǎng)絡(luò)。裂隙巖體滲流問題涉及核廢料處置、地?zé)豳Y源開發(fā)、油和天然氣開采及CO2地質(zhì)封存等工程領(lǐng)域。深入理解應(yīng)力作用下裂隙巖體的滲流行為對保證這些地質(zhì)工程的安全性能有著重要意義。本文以裂隙巖體為研究對象,通過自主研發(fā)裂隙網(wǎng)絡(luò)巖石滲流綜合模擬和分析系統(tǒng),綜合采用室內(nèi)試驗、理論分析和數(shù)值模擬相結(jié)合的方法,對不同荷載作用下裂隙巖體的滲透特性展開一系列研究工作,對裂隙巖體非線性流動特征與裂隙形式、剪切位移、荷載水平之間的相關(guān)性進行討論,對豐富裂隙巖體水力學(xué)理論起到一定的積極作用。(1)采用高分辨率巖石CT掃描系統(tǒng)對不同應(yīng)力路徑作用后花崗巖試樣內(nèi)部裂隙發(fā)育特征進行三維重構(gòu)。滲流試驗結(jié)果表明,單軸壓縮后花崗巖試樣滲流試驗過程中流速和壓力梯度之間呈現(xiàn)明顯的非線性特征,可以用Forchheimer方程進行描述,系數(shù)a'和b'均隨圍壓σs的增加逐漸增大。導(dǎo)水系數(shù)隨著壓力梯度的增加逐漸降低。常規(guī)三軸和三軸峰前卸荷試驗后花崗巖試樣流速和壓力梯度之間均呈現(xiàn)近似線性關(guān)系,試樣等效滲透系數(shù)均隨圍壓σs的增加逐漸減小,而隨圍壓σ_3的變化特征存在一定差異。(2)自主研發(fā)一臺裂隙網(wǎng)絡(luò)巖石滲流綜合模擬和分析系統(tǒng),展開一系列含不同剪切位移三維粗糙單裂隙的滲流試驗。流體的流動行為均可以用Forchheimer和Izbash定律進行描述。隨著剪切位移的增加,Forchheimer擬合方程中線性和非線性項系數(shù)a和b均逐漸減小,Izbash擬合方程中系數(shù)λ減小了 2～3個數(shù)量級,而系數(shù)m在1.35～1.80范圍內(nèi)波動。裂隙剪切滲流過程中導(dǎo)水系數(shù)和雷諾數(shù)之間可以用多項式函數(shù)進行擬合分析。隨著剪切位移的增加,裂隙導(dǎo)水系數(shù)、臨界水力梯度和等效水力隙寬均逐漸增大。(3)裂隙網(wǎng)絡(luò)巖石試樣的滲流特征均可以用Forchheimer和Izbash函數(shù)進行描述�；貧w擬合系數(shù)a和b隨荷載水平的增加逐漸增大,而隨裂隙網(wǎng)絡(luò)夾角和交叉點個數(shù)的增加逐漸減小。隨著裂隙網(wǎng)絡(luò)夾角和交叉點個數(shù)的增加,試樣導(dǎo)水系數(shù)均逐漸增大,而臨界水力梯度和臨界雷諾數(shù)總體呈現(xiàn)逐漸減小的趨勢。隨著側(cè)壓力系數(shù)的增加,試樣的滲透特性逐漸減弱,而臨界水力梯度和臨界雷諾數(shù)均逐漸增大。與荷載水平Fx=Fy作用下相比,對于不同側(cè)壓力系數(shù),(F_y-F_x)越大,試樣的滲流特性差異越明顯。(4)建立應(yīng)力作用下裂隙巖體滲透特性理論模型,采用COMSOL Multiphysics多物理場仿真軟件對單裂隙和裂隙網(wǎng)絡(luò)的滲透特性進行計算。對于單裂隙,隨著時間的增加,平均導(dǎo)水系數(shù)先逐漸增加后趨于穩(wěn)定,穩(wěn)定后平均導(dǎo)水系數(shù)隨裂隙傾角和上覆巖層壓力的增加逐漸減小,而隨進水口壓力和初始裂隙隙寬的增加逐漸增大。裂隙網(wǎng)絡(luò)夾角和交叉點個數(shù)對裂隙有效應(yīng)力、裂隙隙寬、水壓力和滲流通道均產(chǎn)生影響,隨著裂隙網(wǎng)絡(luò)夾角和交叉點個數(shù)的增加,模型出水口處整體流速均逐漸增大。
[Abstract]:Due to the geological and anthropogenic disturbance, natural rock mass usually occurrence crack or crack network. Seepage problems involving nuclear waste disposal, exploitation of geothermal resources, oil and gas exploration and geological sequestration of CO2 and other engineering fields. Understanding should be seepage behaviors of fractured rock under the action of force is very important to ensure the safety of these geological engineering. The fractured rock mass as the research object, through independent research and development of rock fracture network seepage simulation and analysis system, combined with indoor test, method of combining theoretical analysis and numerical simulation, seepage characteristics of fractured rock mass under different loads to launch a series of research work on flow characteristics and fracture forms, nonlinear fractured rock mass shear displacement, the correlation between the load level are discussed, to enrich the rockmass hydraulic theory will play a positive role . (1) using high resolution CT scanning system of rock stress after the granite specimen fracture characteristics of three-dimensional reconstruction of different seepage. Test results show that the obvious nonlinear characteristics between velocity and pressure gradient in uniaxial compression after granite sample seepage test process can be described by Forchheimer equation, and the coefficient of A'B' increases with confining pressure. S increases gradually. The water conduction coefficient with the increase of pressure gradient decreases gradually. Between the conventional three axis and three axis pre peak unloading test of granite after sample flow rate and pressure gradient showed a linear relation with the equivalent permeability coefficient increases, confining pressure. S decreased gradually, and the change with confining pressure. _3 there are certain differences. (2) developed a comprehensive rock fracture network seepage simulation and analysis system, launched a series of shear displacement with different roughness A single fracture seepage test. The flow behavior of the fluid can be used Forchheimer and Izbash law are described. With the increase of shear displacement, Forchheimer equation in linear and nonlinear coefficient of a and B were decreased, Izbash coefficient in fitting equation is reduced by 2~3 orders of magnitude, and the coefficient of m in the range of 1.80 ~ 1.35 fluctuations between fracture shear seepage problems of water coefficient and Reynolds number can use polynomial fitting analysis. With the increase of shear displacement, fracture conductivity, critical hydraulic gradient and the equivalent hydraulic aperture increase gradually. (3) the characteristics of seepage in fracture network of rock specimen can be used Forchheimer and Izbash functions are described. The regression coefficients of a and B with the load level increases gradually, and with the increase of fracture network angle and the intersection number decreases. With the fracture network and cross angle Increase the number of samples, the water conduction coefficient increased, while the critical hydraulic gradient and the critical Reynolds number showed a decreasing trend. With the increase of the lateral pressure coefficient, permeability of specimens gradually weakened, while the critical hydraulic gradient and the critical Reynolds number increased gradually. Compared with the level of load under the action of Fx=Fy, for different side pressure coefficient, the greater the difference (F_y-F_x), the seepage characteristics of samples is more obvious. (4) shall establish a theoretical model of permeability characteristic of fractured rock mass under the force of permeability by COMSOL Multiphysics multiphysics simulation software of single fracture and fracture network were calculated. For a single fracture, with the increase of time, average the water conduction coefficient first increased and then tended to be stable, increase the stability of the average water conduction coefficient with dip angle and the overburden pressure gradually decreases, while with the inlet pressure and the initial crack width. With increasing gradually, the number of intersection points and the number of intersections of fractured network will influence the effective stress, the width of the fracture gap, the water pressure and the seepage channel. With the increase of the number of intersection points and the number of intersection points, the flow velocity at the outlet of the model will gradually increase.

【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TU45
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本文編號：1508900