本文關(guān)鍵詞： 塊石膠結(jié)充填體 損傷 破壞模式 聲發(fā)射概率密度函數(shù) 聲發(fā)射速率過程理論　出處：《江西理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：聲發(fā)射、應(yīng)力、應(yīng)變參量三者均屬材料本構(gòu)參量,對塊石膠結(jié)充填體進(jìn)行穩(wěn)定性評(píng)價(jià)時(shí),其受力歷史是未知的,很難根據(jù)應(yīng)力應(yīng)變參量的本構(gòu)關(guān)系來評(píng)價(jià),而材料聲發(fā)射由于具有不可逆性,正好彌補(bǔ)了這一不足。因?yàn)榧虞d過程中的微裂紋擴(kuò)展速率可以利用聲發(fā)射事件的概率密度表征,本文擬應(yīng)用學(xué)者Dai和學(xué)者Labuz研究脆性材料(混凝土、巖石等)聲發(fā)射特性時(shí)提及的聲發(fā)射事件累積數(shù)N與應(yīng)力水平σ%間的聲發(fā)射事件概率密度函數(shù),通過不同骨料配比塊石膠結(jié)充填體單軸加載聲發(fā)射試驗(yàn),獲得承載過程不同時(shí)刻的聲發(fā)射累積數(shù),根據(jù)計(jì)算公式得出聲發(fā)射事件概率密度,通過聲發(fā)射事件概率密度與應(yīng)力水平關(guān)系曲線分析,表征單軸載荷下塊石膠結(jié)充填體不同強(qiáng)度等級(jí)(骨料配比不同)力學(xué)參數(shù)(相對應(yīng)力水平)與聲發(fā)射參數(shù)(聲發(fā)射事件概率密度)的關(guān)系。綜上所述,本文主要研究結(jié)論如下:(1)通過分析不同塊石含量膠結(jié)充填體破壞過程全應(yīng)力-應(yīng)變曲線,根據(jù)曲線的變化特征可以將充填體試樣變形過程劃分為壓密、彈性變形、屈服變形、破壞以及殘余承載五階段;塊石含量的增加在一定程度上減少了垂直于壓應(yīng)力方向的原始微裂隙、孔隙數(shù)量,改善了塊石膠結(jié)充填體初始內(nèi)部結(jié)構(gòu)。(2)隨著塊石含量增加,累計(jì)聲發(fā)射事件數(shù)快速增長階段(直線段)出現(xiàn)由壓密段向塑性段過渡的明顯趨勢;由于累計(jì)聲發(fā)射事件數(shù)與損傷存在關(guān)聯(lián),因此,在塊石含量的影響下,整個(gè)承載過程膠結(jié)充填體損傷的主要階段出現(xiàn)后移趨勢;塊石含量較低時(shí),整個(gè)承載過程中損傷值及其變化規(guī)律比較接近純尾砂膠結(jié)充填體,塊石含量持續(xù)增加,達(dá)到45%左右時(shí),中等應(yīng)力水平以下(應(yīng)力水平小于50%),損傷值變化不明顯,且一直在較低水平波動(dòng),說明塊石含量增加對尾砂膠結(jié)充填體承載前期的損傷具有較好的抑制作用。(3)通過分析大量聲發(fā)射試驗(yàn)數(shù)據(jù)得到,塊石膠結(jié)充填體的破裂模式主要可以分為劈裂破裂模式、條形破裂模式和爆裂破裂模式;這些破裂模式的形成均由塊石含量的變化引起;將聲發(fā)射參數(shù)和塊石含量建立聯(lián)系,擬合得出聲發(fā)射速率參數(shù)a,根據(jù)其變化趨勢可得到三種塊石膠結(jié)充填體破壞判別模式,即持續(xù)減小趨勢可判別該試件為劈裂破壞;隨時(shí)間上下波動(dòng)無明顯上升或下降趨勢可判別為條形破壞;小幅波動(dòng)出現(xiàn)急速上漲可判別為爆裂破壞。
[Abstract]:Acoustic emission, stress and strain parameters all belong to the constitutive parameters of materials. When evaluating the stability of cemented filling body, the history of stress is unknown, so it is difficult to evaluate the constitutive relationship of stress and strain parameters. Due to the irreversibility of the material acoustic emission (AE) makes up for this deficiency because the microcrack propagation rate in the loading process can be characterized by the probability density of the AE event. This paper intends to apply Dai and Labuz to study brittle materials (concrete). The probability density function of AE event between the cumulative number of AE events N and stress level 蟽% mentioned in acoustic emission (AE) characteristics is tested by uniaxial loading of block cemented filling body with different aggregate ratio. The cumulative number of acoustic emission at different time in the loading process is obtained and the probability density of acoustic emission event is obtained according to the calculation formula. The relationship between the probability density of acoustic emission event and the stress level is analyzed by means of the curve of the probability density of acoustic emission event. The relationship between mechanical parameters (corresponding force level) and acoustic emission parameters (AE event probability density) under uniaxial loading is characterized. The main conclusions of this paper are as follows: (1) by analyzing the total stress-strain curves of cemented filling with different rock contents, the deformation process of filling samples can be divided into compaction according to the changing characteristics of the curves. Elastic deformation, yield deformation, failure and residual loading; The increase of rock mass content to some extent reduces the original micro-fractures perpendicular to the compressive stress direction, the number of pores, and improves the initial internal structure of the block cemented filling. 2) with the increase of rock mass content. The accumulative number of acoustic emission events in the rapid growth stage (straight line section) shows a clear trend from the compaction section to the plastic segment. Because of the correlation between the cumulative number of AE events and the damage, the main damage stage of cemented backfill appears backward trend under the influence of rock mass content. When the rock content is low, the damage value and its change law are close to the pure tailings cemented filling body during the whole loading process, and the rock mass content continues to increase, reaching about 45%. Below the medium stress level (the stress level is less than 50%), the damage value is not obvious, and has been fluctuating in the lower level. It shows that the increase of rock mass content has a better inhibition effect on the damage of tailings cemented filling in the early loading stage. (3) by analyzing a large number of acoustic emission test data. The fracture modes of the cemented filling body can be divided into split fracture mode, stripe fracture mode and burst fracture mode. The formation of these fracture modes is caused by the change of rock mass content. The acoustic emission parameters are related with the mass content, and the acoustic emission rate parameters a are fitted. According to the change trend, three kinds of failure discrimination models of cemented filling body can be obtained. That is to say, the continuous decreasing trend can distinguish the specimen as splitting failure; There is no obvious upward or downward trend with time fluctuation, which can be identified as strip failure. Small fluctuation appears rapid rise can be distinguished as burst damage.
【學(xué)位授予單位】：江西理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TD853.34

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