本文選題：紅砂巖　切入點(diǎn)：蠕變破壞　出處：《江西理工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：巖石蠕變現(xiàn)象廣泛存在于各類地下工程中,對(duì)巖石蠕變聲發(fā)射特性進(jìn)行研究,將有利于工程穩(wěn)定性的監(jiān)測(cè)。本文在紅砂巖蠕變聲發(fā)射試驗(yàn)的基礎(chǔ)上,首先研究巖石在蠕變狀態(tài)下應(yīng)變率與聲發(fā)射的關(guān)系,并通過聲發(fā)射表征巖石蠕變損傷過程;然后通過應(yīng)變百分比與聲發(fā)射參數(shù)的關(guān)系,探討了損傷與應(yīng)變的關(guān)系;最后,通過單軸壓縮狀態(tài)下應(yīng)變與聲發(fā)射的關(guān)系,探討了兩種狀態(tài)下巖石的損傷過程,建立巖石蠕變破壞的聲發(fā)射判據(jù)。主要得出以下結(jié)論:(1)巖石在蠕變破壞過程中,聲發(fā)射參數(shù)變化率隨著應(yīng)變率增大而增大;并且聲發(fā)射累計(jì)振鈴計(jì)數(shù)—時(shí)間曲線與蠕變應(yīng)變—時(shí)間曲線具有相似性,在一定程度上可表征巖石的損傷過程。(2)在蠕變破壞過程中,隨著應(yīng)變率的增大,主頻值升高,頻帶范圍變寬。在等速階段主頻主要維持在100~350kHz之間,進(jìn)入加速階段,主頻最大值為500kHz,頻帶基本維持在75~450kHz之間。由此說(shuō)明在蠕變加速階段,巖石內(nèi)部微裂紋不斷萌生、演化貫通形成宏觀裂紋,并且新裂紋的萌生和宏觀裂紋的形成具有同步性。(3)不同應(yīng)變率的紅砂巖蠕變破壞具有相似的應(yīng)變與聲發(fā)射參數(shù)特征。(4)紅砂巖在單軸壓縮狀態(tài)下應(yīng)變率與聲發(fā)射幅度、事件率等無(wú)明顯線性關(guān)系,事件率隨應(yīng)變的增加變化較平穩(wěn),當(dāng)應(yīng)變達(dá)到一定范圍時(shí),事件率開始顯著增加直至破壞;然而,在蠕變狀態(tài)下應(yīng)變率與聲發(fā)射幅度、事件率呈線性關(guān)系,事件率隨應(yīng)變的增加變化較為起伏,在破壞前事件率存在多次“突增”的現(xiàn)象。(5)通過應(yīng)變與聲發(fā)射事件率關(guān)系以及應(yīng)變率與聲發(fā)射幅度、事件率的關(guān)系,可判定巖石的蠕變狀態(tài)。
[Abstract]:Rock creep phenomenon exists widely in various underground projects. The study of rock creep acoustic emission characteristics will be beneficial to the monitoring of engineering stability. This paper is based on the creep acoustic emission test of red sandstone. First, the relationship between strain rate and acoustic emission in creep state of rock is studied, and the creep damage process of rock is characterized by acoustic emission, then the relationship between damage and strain is discussed by the relationship between strain percentage and acoustic emission parameter. Based on the relationship between strain and acoustic emission in uniaxial compression state, the damage process of rock under two states is discussed, and the acoustic emission criterion of rock creep failure is established. The rate of change of acoustic emission parameters increases with the increase of strain rate, and the accumulative ringing counting-time curve of acoustic emission is similar to that of creep strain-time curve, which can be used to characterize the damage process of rock in the process of creep failure to a certain extent. With the increase of strain rate, the value of main frequency increases and the range of frequency band becomes wider. In the constant speed stage, the main frequency is kept between 100 kHz and 350 kHz, and the maximum value of main frequency is 500 kHz, and the frequency band is basically maintained at 75450kHz, which shows that in the creep acceleration stage, the maximum frequency is 500 kHz and the frequency band is between 75kHz and 450 kHz. The microcracks in rock continuously germinate and evolve through to form macroscopic cracks. Moreover, the initiation of new cracks and the formation of macroscopic cracks have synchronism. 3) the creep failure of red sandstone with different strain rates has similar strain and acoustic emission parameters. 4) under uniaxial compression, the strain rate and acoustic emission amplitude of red sandstone are similar. There is no obvious linear relationship between event rate and so on. The change of event rate with the increase of strain is more stable. When strain reaches a certain range, the event rate begins to increase significantly until it is destroyed, however, under creep condition, strain rate and acoustic emission amplitude, The event rate shows a linear relationship, and the event rate fluctuates with the increase of strain. The phenomenon of "sudden increase" exists in the event rate before destruction. The relationship between strain and AE event rate, the relationship between strain rate and AE amplitude and event rate is obtained. The creep state of rock can be determined.
【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】：2016
【分類號(hào)】：TU45

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