水對煤樣力學(xué)性質(zhì)與破壞形式的影響
發(fā)布時間：2018-11-06 20:28
【摘要】：中國煤炭資源開采70%左右的產(chǎn)能集中在中西部干旱半干旱區(qū)域,而水資源是制約該區(qū)域煤炭資源大規(guī)模開采的關(guān)鍵因素之一。當(dāng)前,保水開采和采空區(qū)地下水庫儲水已成為緩解該區(qū)域水資源日趨緊張的關(guān)鍵技術(shù)。通過研究水對煤樣裂隙發(fā)育和破壞形式的影響規(guī)律,對采空區(qū)地下水庫儲水煤柱壩體尺寸設(shè)計、保水開采導(dǎo)水裂隙帶高度計算等具有重要意義。為探究水對煤樣力學(xué)性質(zhì)的影響,利用自制無損浸水實驗裝置控制煤樣(西沙河煤礦,長方體試樣;新橋煤礦,標(biāo)準(zhǔn)圓柱體試樣)含水率并結(jié)合煤樣吸水變化規(guī)律,確定了西沙河煤樣含水率選擇分別為0、2.37%、3.78%和5.29%,新橋煤礦標(biāo)準(zhǔn)圓柱型煤樣含水率選擇為0、4.98%、9.92%和12.33%。通過單軸壓縮實驗研究發(fā)現(xiàn):煤樣含水率隨著浸水時間呈現(xiàn)快速增長期、緩慢增長期和穩(wěn)定期。煤樣的峰值應(yīng)力、強度軟化系數(shù)、彈性模量、應(yīng)變軟化模量、后峰值模量均隨著含水率增加而呈現(xiàn)不同程度的減小,而峰值應(yīng)變隨著含水率的增加而增加,表明了水對煤樣力學(xué)性質(zhì)具有明顯弱化作用。通過聲發(fā)射(AE)、X射線衍射(XRD)、電鏡掃描(SEM)和壓汞實驗(MIP)等方法研究了水對煤巖裂隙擴展規(guī)律和煤樣破壞形式的內(nèi)在機理。研究表明:具有很高親水性的伊利石是影響煤樣吸水性的主要粘土礦物;結(jié)合剛度-應(yīng)力和聲發(fā)射累計計數(shù)-應(yīng)力關(guān)系曲線,不同含水率煤樣的裂隙發(fā)育階段可利用累計計數(shù)-應(yīng)力關(guān)系劃分5個階段,即壓密,彈性,裂隙穩(wěn)定發(fā)育,不穩(wěn)定發(fā)育和峰后階段;煤樣聲發(fā)射活動集中出現(xiàn)在D點(裂隙損傷閾值)之后。同時,研究發(fā)現(xiàn)煤樣的裂隙壓密應(yīng)力閾值,初始發(fā)育閾值和損傷閾值隨著含水率增大而減小,但其值占峰值強度的比值不變,分別為14.80%,29.93%和72.71%;隨著含水率增大,煤樣聲發(fā)射活性減弱,聲發(fā)射累計振鈴計數(shù)減小,同時弱化了煤樣內(nèi)部顆粒連接,增加了煤樣滑動破壞的可能性。通過對比分析聲發(fā)射的RA和AF值發(fā)現(xiàn):所有煤樣裂隙呈現(xiàn)張剪復(fù)合型裂隙,無單一拉伸或者剪切裂隙出現(xiàn)。但隨著含水率增大,煤樣的總裂隙和張裂隙數(shù)目均減少,但剪切裂隙比例卻明顯增大。水作用下煤樣RA-AF值核心區(qū)域向低AF高RA區(qū)域靠攏,煤樣的宏觀裂隙形態(tài)主要表現(xiàn)為裂隙充分發(fā)育,剪切裂隙集聚甚至貫穿,最后煤樣破壞表現(xiàn)為以剪切破壞為主的可能性大大增加。
[Abstract]:About 70 percent of China's coal production capacity is concentrated in arid and semi-arid areas in the central and western regions, and water resources are one of the key factors restricting large-scale exploitation of coal resources in this region. At present, water conservation and water storage in underground reservoirs in goaf have become the key technology to alleviate the increasing shortage of water resources in this area. By studying the influence of water on the development and failure form of coal fracture, it is of great significance to design the size of coal pillar dam of underground reservoir in goaf and to calculate the height of water-conducting fissure zone in water-retaining mining. In order to investigate the influence of water on the mechanical properties of coal samples, coal samples were controlled by self-made non-destructive soaking device (Xishahe coal mine, cuboid sample); In Xinqiao Coal Mine, standard cylinder sample) moisture content, combined with water absorption law of coal sample, determined that the selection of water cut in Xishahe coal sample was 0.2.373.78% and 5.29%, respectively. The water content of standard cylindrical briquette in Xinqiao Coal Mine was chosen to be 0 ~ 4.98% and 12.33% respectively. Through uniaxial compression experiments, it is found that the moisture content of coal samples increases rapidly, slowly and steadily with the soaking time. The peak stress, strength softening coefficient, elastic modulus, strain softening modulus and post-peak modulus of coal samples all decreased with the increase of moisture content, but the peak strain increased with the increase of water content. It is shown that water has an obvious weakening effect on the mechanical properties of coal samples. By means of acoustic emission (AE), X ray diffraction (XRD), electron microscope scanning (SEM) and mercury injection experiment (MIP) the law of water crack propagation and the internal mechanism of coal sample failure were studied. The results show that Illite with high hydrophilicity is the main clay mineral affecting the water absorption of coal samples. According to the curve of the relationship between stiffness and stress and acoustical emission accumulative counting and stress, the fracture development stage of coal samples with different moisture content can be divided into five stages by accumulative counting and stress relationship, that is, compaction, elasticity and stable development of fractures. Unstable development and postpeak stage; The acoustic emission activity of coal samples occurs after D point (crack damage threshold). At the same time, it is found that the compressive stress threshold, initial development threshold and damage threshold of coal samples decrease with the increase of water content, but the ratio of the values to the peak strength of coal samples is 14.800.93% and 72.71%, respectively. With the increase of water content, the acoustic emission activity of coal sample decreases, and the accumulative ring number of acoustic emission decreases, at the same time, the internal particle connection of coal sample is weakened, and the possibility of slippage failure of coal sample is increased. By comparing the RA and AF values of acoustic emission, it is found that all the fractures in coal samples show tension-shear composite fractures, and no single tensile or shear fractures appear. However, with the increase of water content, the number of total fractures and tensile fractures of coal samples decreases, but the ratio of shear fractures increases obviously. Under the action of water, the core area of RA-AF value of coal sample is closer to the area with low AF and high RA. The macroscopic fracture morphology of coal sample mainly shows that the fracture is fully developed, and the shear fracture accumulates and even runs through. Finally, the possibility of shear failure is greatly increased.
【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】：TD821
本文編號：2315379
[Abstract]:About 70 percent of China's coal production capacity is concentrated in arid and semi-arid areas in the central and western regions, and water resources are one of the key factors restricting large-scale exploitation of coal resources in this region. At present, water conservation and water storage in underground reservoirs in goaf have become the key technology to alleviate the increasing shortage of water resources in this area. By studying the influence of water on the development and failure form of coal fracture, it is of great significance to design the size of coal pillar dam of underground reservoir in goaf and to calculate the height of water-conducting fissure zone in water-retaining mining. In order to investigate the influence of water on the mechanical properties of coal samples, coal samples were controlled by self-made non-destructive soaking device (Xishahe coal mine, cuboid sample); In Xinqiao Coal Mine, standard cylinder sample) moisture content, combined with water absorption law of coal sample, determined that the selection of water cut in Xishahe coal sample was 0.2.373.78% and 5.29%, respectively. The water content of standard cylindrical briquette in Xinqiao Coal Mine was chosen to be 0 ~ 4.98% and 12.33% respectively. Through uniaxial compression experiments, it is found that the moisture content of coal samples increases rapidly, slowly and steadily with the soaking time. The peak stress, strength softening coefficient, elastic modulus, strain softening modulus and post-peak modulus of coal samples all decreased with the increase of moisture content, but the peak strain increased with the increase of water content. It is shown that water has an obvious weakening effect on the mechanical properties of coal samples. By means of acoustic emission (AE), X ray diffraction (XRD), electron microscope scanning (SEM) and mercury injection experiment (MIP) the law of water crack propagation and the internal mechanism of coal sample failure were studied. The results show that Illite with high hydrophilicity is the main clay mineral affecting the water absorption of coal samples. According to the curve of the relationship between stiffness and stress and acoustical emission accumulative counting and stress, the fracture development stage of coal samples with different moisture content can be divided into five stages by accumulative counting and stress relationship, that is, compaction, elasticity and stable development of fractures. Unstable development and postpeak stage; The acoustic emission activity of coal samples occurs after D point (crack damage threshold). At the same time, it is found that the compressive stress threshold, initial development threshold and damage threshold of coal samples decrease with the increase of water content, but the ratio of the values to the peak strength of coal samples is 14.800.93% and 72.71%, respectively. With the increase of water content, the acoustic emission activity of coal sample decreases, and the accumulative ring number of acoustic emission decreases, at the same time, the internal particle connection of coal sample is weakened, and the possibility of slippage failure of coal sample is increased. By comparing the RA and AF values of acoustic emission, it is found that all the fractures in coal samples show tension-shear composite fractures, and no single tensile or shear fractures appear. However, with the increase of water content, the number of total fractures and tensile fractures of coal samples decreases, but the ratio of shear fractures increases obviously. Under the action of water, the core area of RA-AF value of coal sample is closer to the area with low AF and high RA. The macroscopic fracture morphology of coal sample mainly shows that the fracture is fully developed, and the shear fracture accumulates and even runs through. Finally, the possibility of shear failure is greatly increased.
【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】：TD821
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