本文選題：巖石力學(xué) + 霍普金森壓桿�。� 參考：《河南理工大學(xué)》2016年博士論文

【摘要】：沖擊地壓是影響煤礦安全生產(chǎn)的重大災(zāi)害之一。沖擊地壓的形成常以震源沖擊應(yīng)力波的方式通過煤巖介質(zhì)傳遞至采掘空間,造成沖擊地壓事故,煤層注水是沖擊地壓防治常用方法之一,靜載型沖擊地壓煤層注水使沖擊傾向性降低,但深部煤層常處于動靜組合加載的應(yīng)力環(huán)境下,含水煤層的應(yīng)力波傳播衰減、強(qiáng)度、能量耗散的強(qiáng)弱機(jī)理尚不清楚,含水煤樣沖擊動力響應(yīng)是沖擊地壓防治亟待解決的理論問題。利用RMT-150C和改進(jìn)SHPB系統(tǒng)進(jìn)行了煤樣靜載、動靜組合加載試驗,探討了不同含水煤樣的動態(tài)強(qiáng)度、失穩(wěn)破壞、應(yīng)力波衰減、能量耗散、損傷斷裂等特征,主要結(jié)論及認(rèn)識如下:(1)采用RMT-150C伺服試驗系統(tǒng)對自然、飽水3d、7d煤樣進(jìn)行單軸和三軸抗壓強(qiáng)度的靜載試驗,單軸及三軸抗壓強(qiáng)度隨飽水時間增加而逐漸降低;三軸壓縮作用下自然和飽水7d煤樣的應(yīng)力-應(yīng)變曲線峰后差異較明顯,自然狀態(tài)煤樣峰后應(yīng)力跌落速度較快(脆性破壞特征),飽水7d煤樣峰后應(yīng)力跌落較為緩慢(塑性破壞特征);基于微元強(qiáng)度服從Weibull分布,建立了單軸壓縮含水煤樣的統(tǒng)計損傷本構(gòu)模型,并進(jìn)行驗證。(2)探討了異形沖頭法消除彌散效應(yīng)和應(yīng)力均勻問題,確定煤樣動態(tài)加載尺寸為φ50mm×30mm;飽水后煤樣橫波傳播速度基本不變,縱波傳播速度增加明顯,應(yīng)力波衰減系數(shù)減小;利用改進(jìn)SHPB系統(tǒng)對自然、飽水3d、飽水7d煤樣分別進(jìn)行了一維動靜組合加載試驗,煤樣的動態(tài)應(yīng)力-應(yīng)變曲線特征與靜載差異較大,煤樣動態(tài)強(qiáng)度隨飽水時間增加逐漸降低,但彈性模量少量升高,動態(tài)強(qiáng)度與彈性模量高于靜載強(qiáng)度及彈性模量;針對預(yù)加靜載對煤樣裂隙發(fā)展影響,將煤樣裂隙分為裂隙壓縮穩(wěn)定階段、裂隙急劇擴(kuò)展階段、裂隙貫通階段;煤樣的動態(tài)強(qiáng)度呈現(xiàn)先升高后降低的趨勢,軸向預(yù)靜載大于靜載強(qiáng)度的50%-52%(臨界靜載點)后,一維動靜組合動態(tài)強(qiáng)度開始下降。(3)三維動靜組合加載的相同圍壓不同軸壓試驗中,軸向靜載在煤樣彈性范圍內(nèi)其動態(tài)強(qiáng)度隨軸向靜載增加而增加,飽水7d煤樣的動態(tài)強(qiáng)度比自然狀態(tài)煤樣有不同程度的增高,與靜載、一維動靜組合加載結(jié)果相反;相同軸壓不同圍壓加載時,隨著圍壓增大自然和飽水7d煤樣的動態(tài)強(qiáng)度均有增大,彈性模量也相應(yīng)增加;對一維、三維動靜組合加載煤樣的應(yīng)力-應(yīng)變曲線特征分為4個階段:壓密階段、彈性階段、裂紋擴(kuò)展階段、卸載階段。(4)運(yùn)用斷裂損傷力學(xué)理論,分析了裂隙尖端應(yīng)力場演化特征,建立了靜載、動靜組合加載條件下含水張開翼型裂紋模型;分析了裂隙水壓作用下煤樣裂隙動態(tài)起始、傳播與止裂判據(jù),建立了靜載、單獨動載、動靜組合加載條件下含水煤樣的抗壓強(qiáng)度數(shù)學(xué)表達(dá)式,并探討了含水煤樣及巖石類材料動態(tài)抗壓強(qiáng)度增加或降低的原因;確定了一維動靜組合加載含水煤樣損傷變量,建立了含水和動靜組合加載條件下煤樣的本構(gòu)模型,并對模型進(jìn)行驗證。(5)一維動靜組合加載自然煤樣破壞所需時間大于飽水煤樣破壞需要時間,煤樣破碎顆粒隨飽水時間增長而逐漸變小;相同含水試樣破壞失穩(wěn)耗散能量越大,破碎塊度越小,分形維數(shù)越大;自然煤樣分形維數(shù)小于飽水3d、7d,分維數(shù)隨著能耗密度的增加而提高,能耗密度與分形維數(shù)增幅均呈正相關(guān);相同能耗密度隨飽水時間增長粒度逐漸減小,能耗密度與破碎粒度呈負(fù)相關(guān),二者具有良好線性關(guān)系,水作用對試樣粒徑影響顯著。
[Abstract]:The impact ground pressure is one of the major disasters that affect the safety of production in coal mines. The formation of rock impact pressure is often passed through the coal rock medium through the source impact stress wave to the excavation space, causing the rockburst accident. The coal seam flooding is one of the commonly used methods for the prevention and control of the impact ground pressure. Under the stress environment of combined loading and static loading, the stress wave propagation attenuation, strength and energy dissipation mechanism of the water bearing coal seam are still unclear. The impact dynamic response of the water bearing coal sample is a theoretical problem to be solved urgently. The static load and static combined loading test of coal samples are carried out with the RMT-150C and the improved SHPB system. The characteristics of dynamic strength, instability and failure, stress wave attenuation, energy dissipation and damage fracture are discussed. The main conclusions and understanding are as follows: (1) the RMT-150C servo test system is used to carry out static load tests on natural, saturated 3D and 7d coal samples with uniaxial and three axis compressive strength, and the uniaxial and three axis compressive strength increases with the filling time. Gradually decreasing, the stress strain curve of natural and full water 7d coal samples under three axis compression has obvious difference after peak stress strain curve peak, and the stress drop velocity after coal sample peak in natural state is faster (brittle failure characteristic), and the stress drop of 7D coal sample is slow after the peak of full water (the characteristic of plastic failure), and the strength of micro element is subordinate to Weibull distribution, and the uniaxial compression is established. The statistical damage constitutive model of coal water samples is verified. (2) the problem of eliminating dispersion and stress uniformity is discussed. The dynamic loading size of coal samples is determined to be 50mm x 30mm; the transverse wave propagation velocity of coal sample after full water is basically unchanged, the propagation velocity of longitudinal wave increases obviously, and the attenuation coefficient of stress wave decreases; and the improved SHPB system is used to self control. The dynamic stress strain curve of coal sample is different from static load, and the dynamic strength of coal sample decreases gradually with the increase of water filling time, but the modulus of elasticity increases slightly, and the dynamic strength and modulus of elasticity are higher than static load and elastic modulus, and the preloading static load is on the basis of preloading static load on 3D. The coal sample cracks are divided into the stage of fracture compression stability, the sharp expansion stage and the fracture penetration stage, the dynamic strength of coal sample increases first and then decreases, and the dynamic strength of one dimension dynamic static combination begins to decline after the axial static load is larger than the static load strength of 50%-52% (critical static load point). (3) three dimensional dynamic and static combination In the same confining pressure test, the dynamic strength of the axial static load increases with the axial static load in the elastic range of the coal sample, and the dynamic strength of the 7d coal sample is higher than that of the natural coal sample. It is opposite to the static load, the one dimensional static combined loading result, and the confining pressure increases with the same axial pressure. The dynamic strength of natural and full water 7d coal samples increased and the modulus of elasticity increased correspondingly. The stress strain curves of one dimension, three-dimensional dynamic combined loading coal samples were divided into 4 stages: compaction stage, elastic stage, crack growth stage, unloading stage. (4) the fracture damage mechanics theory was used to analyze the evolution characteristics of the stress field at the crack tip. The crack model of water opening airfoil under static loading and static combined loading was established, and the dynamic initiation, propagation and crack arrest criteria of coal samples under the action of fracture water pressure were analyzed. The mathematical expression of compressive strength of water bearing coal samples under static load, single dynamic load and static combined loading condition was established, and the dynamic behavior of water bearing coal samples and rock like materials was discussed. The reason for increasing or decreasing the compressive strength; determining the damage variable of one dimensional static combined loading water bearing coal sample, establishing the constitutive model of coal samples under the combined loading condition of water and static and static loading, and verifying the model. (5) the time required for the destruction of natural coal sample with one dimension static combined loading is greater than that of the coal sample destruction time and the broken coal particles The fractal dimension of natural coal sample is smaller and the fractal dimension is smaller than that of 3D, 7d, the fractal dimension increases with the increase of energy consumption density, and the energy density is positively correlated with the increase of fractal dimension, and the same energy density increases with the filling time. The length of granularity gradually decreases, and the energy consumption density is negatively correlated with the particle size. The two have a good linear relationship, and the effect of water on the particle size is significant.

【學(xué)位授予單位】：河南理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TD324

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本文編號：1875383