本文選題：煤礦開采 + 貫通破壞　； 參考：《中國礦業(yè)大學(xué)(北京)》2017年博士論文

【摘要】：本文圍繞采動條件下覆巖破壞及裂隙演化機(jī)理這一科學(xué)問題展開了研究,通過現(xiàn)場實測、理論分析、物理模型試驗、數(shù)值模擬和實驗室試驗等方法,對采動條件下拱形裂隙類巖體破壞機(jī)理及其模型進(jìn)行了研究,提出了采動過程中覆巖隨著礦壓顯現(xiàn)而形成拱形裂隙的理念,提出了三角拱形和“W”拱形兩類裂隙簡化模型,并構(gòu)建了與礦壓顯現(xiàn)相結(jié)合的解釋采動覆巖拱形裂隙空間展布、衍生特征及動態(tài)發(fā)育的三角拱形裂隙演化模型和“W”拱形裂隙演化模型;建立了初始拱形裂隙損傷開采模型和無初始損傷開采相似材料對比模型,對采動覆巖裂隙形態(tài)變化、分形及沉降特征進(jìn)行了研究,并對演化模型進(jìn)行了驗證;結(jié)合UDEC數(shù)值模擬方法,構(gòu)建了與相似材料模型一致的模型及其他兩個考慮裂隙拱前后傾角、拱形裂隙層數(shù)因素的模型,歸納了不同初始拱形預(yù)制裂隙分布特征對覆巖采動裂隙演化影響的規(guī)律;通過制備四類裂隙形態(tài)、六組傾角范圍的預(yù)制拱形裂隙類巖石試件,對其在單軸壓縮加載條件下的破壞行為及模式進(jìn)行了試驗研究,揭示了三角拱形裂隙和“W”拱形裂隙隨裂隙傾角變化對類巖石試件的強(qiáng)度與彈性模量、起裂擴(kuò)展貫通裂紋形態(tài)與傾角的影響規(guī)律,對于地下工程開挖中地質(zhì)災(zāi)害的預(yù)測與防治,具有一定的參考價值和實踐意義。本文的主要研究成果如下:(1)通過轉(zhuǎn)龍灣煤礦頂板拱形裂隙發(fā)育形態(tài)實測,獲得工作面頂板裂隙發(fā)育形態(tài)為拱形,呈現(xiàn)工作面中間最高,工作面兩側(cè)最低的特征,提出了兩類采動裂隙的簡化模型,即三角拱形(Λ)與W拱形(W);提出了與礦壓顯現(xiàn)相結(jié)合的解釋采動覆巖拱形裂隙空間展布、衍生特征及動態(tài)發(fā)育的三角拱形裂隙演化模型和“W”拱形裂隙演化模型,并結(jié)合提出的兩裂隙演化模型,歸納了隨著來壓步距而發(fā)展的覆巖采動裂隙動態(tài)演化過程、形態(tài)變化、形成時間及發(fā)育規(guī)律;提出了采動過程覆巖主要導(dǎo)水裂隙通道形成規(guī)律,根據(jù)建立的裂隙演化模型,推斷主要導(dǎo)水裂隙通道是煤層開挖過程中沿著工作面推進(jìn)方向的兩個端點向上延伸位置及開挖空間中間位置上方的一次來壓步距裂隙拱。(2)相似材料模擬實驗中,預(yù)制拱形裂隙的開采模型內(nèi)部縱向裂隙發(fā)育更為密集,具有更加明顯地、有規(guī)律地拱形裂隙動態(tài)發(fā)育趨勢,隨著工作面逐漸推進(jìn),裂隙朝著推進(jìn)方向以“拱形”發(fā)育,并逐層向上閉合拱形,而后繼續(xù)延展、連通已存在的小的次生裂隙拱形成新階段的裂隙拱,小拱形裂隙逐漸向前向上發(fā)展形成大裂隙拱;損傷模型的沉降曲線極不規(guī)則,越接近開采初始端沉降中心點越多,煤層上覆巖體由下而上,隨距離煤層頂板高度的增加,上覆巖層沉降量逐漸縮小,各沉降曲線中心點依次沿著推進(jìn)方向偏移;而無初始損傷開采模型的沉降中心點相對較集中;在開采初期(開挖60 m之前)損傷模型的縱向裂隙密度明顯高于無損模型,而在開采后期(開挖60 m~80 m)其與無損模型保持幾近相同的裂隙密度。(3)建立了具有不同初始拱形預(yù)制裂隙分布特征的UDEC數(shù)值模擬模型,發(fā)現(xiàn)損傷開采模型隨著工作面推進(jìn),內(nèi)部縱向裂隙發(fā)育明顯,裂隙形態(tài)以有規(guī)律的小“三角形”或小“拱形”來推進(jìn),形成的裂隙整體形態(tài)則經(jīng)歷著由起初的“等腰三角形”-隨著開采傾斜于切眼的“斜三角形”-采后壓實穩(wěn)定的“拱形”;隨著預(yù)制裂隙角度的降低模型展現(xiàn)出更好的裂隙發(fā)育范圍和內(nèi)部裂隙發(fā)育程度,裂隙發(fā)育更為紊亂、復(fù)雜,裂隙向上擴(kuò)展趨勢越來越不明顯,形態(tài)上由“高瘦”拱形向“矮胖”拱形過渡,在一定的尺度范圍內(nèi),同一階段兩拱形預(yù)制裂隙傾角大、傾角差值大及上下相鄰兩階段預(yù)制裂隙的間距略大有利于覆巖裂隙的縱向擴(kuò)展,而且,雙階段損傷模型比單階段模型具有更好的拱形裂隙發(fā)育趨勢,開采空間覆巖拱形裂隙層數(shù)越多越有利于其拱形趨勢的擴(kuò)展延伸。(4)四類裂隙系列試件中裂隙匯合(即TA和W)或低角度的裂隙傾角都會增加其塑性變形能力,試件中兩預(yù)制裂隙傾角一側(cè)高角度會使其在應(yīng)力應(yīng)變曲線前期受裂隙形態(tài)、匯合等因素的影響程度大幅度的降低,裂隙傾角對其影響占主導(dǎo)地位,裂隙的匯合會造成裂隙巖體抵抗變形能力略微降低,而形態(tài)上的差異,即“W”拱形裂隙在兩側(cè)“V”形的影響下其抵抗變形能力明顯的降低了,可知若是采動覆巖中兩側(cè)“V”形裂隙匯合后將極易破壞;通過比較分析各系列損傷試件峰值強(qiáng)度及彈性模量,獲知“W”拱形裂隙系列對裂隙巖體峰值強(qiáng)度降低程度遠(yuǎn)大于三角拱形,遠(yuǎn)比裂隙匯合帶來的影響嚴(yán)重,對于預(yù)制裂隙試件中同一傾角隨形態(tài)變化的峰值強(qiáng)度,六組裂隙傾角試件分別在I、STA、TA、SW、W下的峰值強(qiáng)度變化基本呈現(xiàn)出隨著形態(tài)變化依次遞減的趨勢,各形態(tài)對峰值強(qiáng)度降低程度從小到大依次為ISTATASWW;而對于預(yù)制裂隙試件中同一傾角的隨形態(tài)變化的彈性模量,六組裂隙傾角試件隨著形態(tài)變化也呈現(xiàn)出大體遞減的趨勢,但不如峰值強(qiáng)度趨勢明顯,而各形態(tài)對彈性模量降低程度與其相同;拱形裂隙試件兩裂隙傾角總和相同的情況下,其差值越大,峰值強(qiáng)度及彈性模量相對越低。(5)獲得了含四類預(yù)制裂隙試件的峰值強(qiáng)度與完整試件的峰值強(qiáng)度之比(/JP P??)、彈性模量與完整試件的彈性模量之比(/JP PE E)與裂隙傾角影響系數(shù)k關(guān)系的經(jīng)驗公式,當(dāng)量化峰值強(qiáng)度隨著傾角影響系數(shù)的遞增呈現(xiàn)出非常好的線性遞減關(guān)系;通過統(tǒng)計裂隙試件起裂、峰值破壞的強(qiáng)度與時間,提出了STA、TA、SW、W四類裂隙系列試件的穩(wěn)定裂隙發(fā)展階段和非穩(wěn)定裂隙發(fā)展階段界限范圍;歸納了不同初始損傷試件裂紋起裂、擴(kuò)展、貫通破壞傾角及跡線形態(tài)變化規(guī)律,發(fā)現(xiàn)對于兩條未匯合的拱形裂隙(STA系列),兩裂隙傾角不同很有可能會引起其中傾角較小的裂隙發(fā)育更為劇烈,并以其為主導(dǎo)引起裂紋繼續(xù)向上擴(kuò)展,同時擴(kuò)寬了向下發(fā)育的裂隙,并且裂隙傾角越大或兩傾角差值越大,這種效果越明顯;對于兩條已匯合的拱形裂隙(TA系列),其中低傾角的裂隙尖端是破壞的薄弱區(qū)域,應(yīng)力多沿此區(qū)域釋放,使得交匯的頂點產(chǎn)生的裂紋繼續(xù)整體保持沿低傾角裂隙傾向于另一側(cè)發(fā)展趨勢;對于兩個未匯合(SW)或已匯合(W)的相同形態(tài)的“V”形裂隙,沿其中低傾角裂隙起裂及擴(kuò)展的趨勢仍很明顯,另外SW系列中隨著裂隙傾角增加,裂隙相互交匯并向上擴(kuò)展的趨勢愈加明顯,低傾角裂隙多朝向垂直于主應(yīng)力方向。
[Abstract]:This paper focuses on the scientific problem of overlying rock failure and fracture evolution mechanism under the mining conditions. Through the field measurement, theoretical analysis, physical model test, numerical simulation and laboratory test, the failure mechanism and model of the arch fractured rock mass under the mining condition are studied, and the overlying rock is put forward in the process of mining. With the idea of forming the arch fissures, the triangle arch and the "W" arch shape simplified models were put forward, and the evolution model of the trigonometric arch fracture and the "W" arch fracture evolution model, which were combined with the ore pressure manifestation, were constructed to explain the spatial distribution of the arch fissures in the mining overlying rock, the derivation characteristics and dynamic development of the arch fissure and the "W" arch fracture. The fracture damage mining model of the beginning arch and the comparison model of similar material without initial damage mining are used to study the fracture morphology, fractal and settlement characteristics of the mining overlying rock, and the evolution model is verified. Combined with the UDEC numerical simulation method, a model consistent with the similar material model and the other two other fracture arches are built. The rule of the influence of the distribution characteristics of different initial arch prefabricated fissures on the fracture evolution of the overlying mining is summed up, and the damage behavior and model of the prefabricated arch fractured rock specimens under the uniaxial compression loading condition are tested and studied by the preparation of four types of fracture morphology and six groups of dip angles. The influence of the triangle arch fracture and the "W" arch crack to the strength and elastic modulus of the rock specimen, the influence law of the crack morphology and dip angle of the crack growth and penetration are revealed. It is of certain reference value and practical significance for the prediction and prevention of geological disasters in the excavation of underground engineering. The results are as follows: (1) through the measurement of the shape of the arch fissures on the roof of the Longwan coal mine, the shape of the crack development in the roof of the working face is arched, showing the highest middle working face and the lowest characteristics on both sides of the working face. The simplified model of two kinds of mining cracks, namely the triangle arch (a) and the W arch (W), is put forward, and the interpretation of the combination with the mineral pressure is put forward. The dynamic evolution process, shape change, formation time and development law of overlying strata, which are developed with the two fissure evolution model, are summed up with the proposed two fracture evolution model. According to the established fracture evolution model, it is concluded that the main water guide fissure channel is an upward extension position of two endpoints along the direction of the coal seam excavation and the one step pressure step distance from the middle position of the excavation space in the process of coal seam excavation. (2) a similar material simulation experiment. The longitudinal fissure development of the prefabricated arch fracture model is more densely developed, and it has a more obvious trend of dynamic development of the arch fracture. With the gradual advance of the working face, the crack is developed in the direction of "arch" in the direction of propulsion, and the arch is closed to the upper level, and then it continues to extend, connecting the small secondary fissure arches. In the new stage, the fracture arch of the small arch is gradually developed forward to form a large fracture arch. The settlement curve of the damage model is very irregular. The more the settlement center point is closer to the initial end of the mining, the overlying rock in the coal seam is up to the bottom, with the increase of the height of the roof of the coal seam, the subsidence of the overlying strata is gradually reduced, and the center points of each settlement curve depend on the center point of the settlement. The center point of the subsidence is relatively concentrated without the initial damage mining model, and the longitudinal fissure density of the damage model is obviously higher than that of the lossless model in the early stage of mining (60 m before excavation), while in the later period of mining (60 m~80 m excavation) it is almost identical to the nondestructive model. (3) it has different initial conditions. The UDEC numerical simulation model of the distribution characteristics of the pre arch prefabricated fissures shows that the damage mining model develops with the working face, and the internal longitudinal fissure development is obvious. The fracture morphology is propelled by the regular small "triangle" or the small "arch". The formation of the whole fracture form is experienced by the initial "isosceles triangle" - with the mining inclination. The "oblique triangle" inclined to the cutting of the eye is the "arch" which is stable after mining. With the reduction of the prefabricated crack angle, the model shows a better range of fracture development and the degree of internal fissure development. The fracture development is more disorganized and complex, and the upward trend of fracture upward is becoming more and more unobvious, and the shape is from "thin" arch to "stout" arch form. In a certain scale, in a certain scale, the two arch prefabricated fissure inclination is large, the angle difference is large and the spacing of the prefabricated fissures in the upper and lower adjacent two stages is slightly extended, and the double stage damage model has a better arch fracture development trend than the single stage model, and the arch fracture of the overlying rock is exploited. The more the number of layers is more beneficial to the expansion and extension of the arch trend. (4) the plastic deformation ability of the fracture confluence (TA and W) or the low angle of the crack will increase the plastic deformation ability. The high angle of the two prefabricated fissure angle in the specimen will be affected by the fracture shape at the early stage of the stress-strain curve, and the influence degree of the confluence is great. With the decrease of the amplitude, the influence of the fracture angle is dominant. The confluence of the fissure will cause a slight decrease in the ability to resist the deformation of the fractured rock mass, but the difference in shape is that the resistance to deformation of the "W" arch crack is obviously reduced under the influence of "V" shape on both sides. It is known that if the "V" fissures on both sides of the mining overlying rock are converged, By comparing and analyzing the peak strength and modulus of elasticity of each series of damage specimens, it is known that the reduction of the peak strength of the fractured rock mass of the "W" arch fracture series is far greater than that of the triangle arch, and the influence of the far ratio of the fracture confluence is serious. For the peak strength of the same dip with the shape change in the prefabricated fracture specimens, the six groups of fissures are tilted. The variation of the peak strength of the angular test parts at I, STA, TA, SW and W showed a trend of decreasing in turn, and the decrease degree of the peak intensity from small to large in each form was ISTATASWW, while the six groups of fracture angles were changed with the morphologic change of the same dip in the prefabricated fissures. There is a tendency to decrease generally, but it is not as obvious as the peak intensity trend, and the degree of the modulus is the same as that of the modulus of elasticity; the greater the difference value, the lower the peak strength and the modulus of elasticity in the case of the two fracture angle of the arch fracture specimen. (5) the peak strength and the complete test of the four types of prefabricated crack specimens are obtained. The peak strength ratio (/JP P?), the empirical formula of the relationship between the modulus of elasticity and the modulus of elasticity of the complete specimen (/JP PE E) and the influence coefficient K of the fracture angle, when the quantitative peak intensity increases with the increase of the inclination influence coefficient, it presents a very good linear decreasing relation; the strength and time of the peak damage through the statistical fracture test. The stable fissure development stage and the boundary range of unstable fissure development stage of four kinds of fracture series of STA, TA, SW, W are put forward, and the crack initiation, expansion, penetration angle and trace form change of different initial damage specimens are summed up, and it is found that the two fissure dip angles are different for two non confluence arch fractures (STA Series). It can cause a more intense development of the smaller slit, which leads to the continuous upward expansion of the crack and the widening of the downward developing fissure, and the greater the slit angle or the greater the difference of the two dip angle, the more obvious the effect is. For the two confluence arch fissures (TA series), the tip of the low dip angle is broken. In the bad weak region, the stress is released along this area, making the cracks at the vertex of the intersection maintain a trend along the other side, and the tendency to crack and expand along the low inclination crack is still obvious for two SW or W confluence (W) fissures with the same shape, and the other SW system Along with the increase of crack dip angle, the trend of fracture convergence and upward expansion is more obvious. The low dip fissure is oriented toward the direction of principal stress.

【學(xué)位授予單位】：中國礦業(yè)大學(xué)(北京)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TD325

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