本文關鍵詞： 大理巖 分級循環(huán)加卸載 損傷 聲發(fā)射 加卸載響應比　出處：《江西理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：金屬礦山實際地下生產(chǎn)作業(yè)中,地下巖體受力狀態(tài)并不穩(wěn)定,受地壓活動及人工擾動的影響,巖體處于頻繁加載及卸載狀態(tài)。為充分了解大理巖在循環(huán)加卸載下?lián)p傷及聲發(fā)射特性,本文以現(xiàn)場及室內(nèi)試驗為基礎,探討了耗散能法及聲發(fā)射法表征大理巖損傷的適用性與差異性;引入加卸載響應比理論,基于聲發(fā)射分析了大理巖在不同應力階段加卸載響應比特征及不同參數(shù)表征加卸載響應比的適用性;結合大理巖原巖應力值,研究了大理巖原始應力點加卸載響應比特征。綜合上述研究內(nèi)容,本文主要結論如下:(1)基于耗散能法表征損傷,大理巖損傷演化曲線總體呈“上凹”狀,瀕臨峰值應力前大理巖損傷變量增大非常明顯。說明在應力加載條件下,基于耗散能法表征大理巖損傷,大理巖損傷主要在裂紋非穩(wěn)定發(fā)展階段,即大理巖損傷主要集中在臨近應力峰值階段。(2)基于聲發(fā)射法表征損傷,同時考慮了大理巖在加載和卸載階段的損傷,大理巖損傷演化曲線呈現(xiàn)出向上彎曲形態(tài),曲線較為平滑且表現(xiàn)出非線性增長跡象。(3)耗散能法與聲發(fā)射法均較適于表征大理巖的損傷演化過程。聲發(fā)射法與耗散能法相比,其優(yōu)勢在于聲發(fā)射法可反映出大理巖在卸載階段的損傷狀況。耗散能法雖不能表征卸載階段的損傷,但能避免聲發(fā)射平靜期的影響。(4)聲發(fā)射撞擊數(shù)、振鈴計數(shù)、能量、Benioff應變表征的大理巖加卸載響應比所呈現(xiàn)的規(guī)律一致,四種參數(shù)表征加卸載響應比具有較高的一致性。振鈴計數(shù)、能量、Benioff應變所表征加卸載響應比優(yōu)于聲發(fā)射撞擊數(shù),以聲發(fā)射能量表征大理巖加卸載響應比隨應力的增加變化幅度更為明顯,在數(shù)值上表現(xiàn)更為靈敏。(5)大理巖隨著應力的增加加卸載響應比總體表現(xiàn)為“下降-平穩(wěn)-升高”。加卸載響應比在初始壓密階段處于較高水平,在彈性變形及微彈性裂隙穩(wěn)定發(fā)展階段基本在1左右波動,進入非穩(wěn)定破裂發(fā)展階段出現(xiàn)明顯升高的現(xiàn)象,大理巖這一特征有助于識別其所處應力狀態(tài),可為工程巖體的穩(wěn)定性判別提供一定的依據(jù)。(6)大理巖原巖應力點所對應的加卸載響應比處在較高水平且明顯大于1,有別于其在彈性變形至裂隙穩(wěn)定發(fā)展階段加卸載響應比穩(wěn)定在1左右這一現(xiàn)象,處于加卸載響應比“下降-平穩(wěn)”間的過渡階段,大理巖這一特征可為其Kaiser效應點的識別提供了一定的依據(jù)。
[Abstract]:In actual underground production of metal mines, the stress state of underground rock mass is unstable, which is affected by ground pressure activity and artificial disturbance. The rock mass is in the state of frequent loading and unloading. In order to fully understand the damage and acoustic emission characteristics of marble under cyclic loading and unloading, this paper is based on field and laboratory tests. The applicability and difference of dissipation energy method and acoustic emission method to characterize the damage of marble are discussed, and the theory of load-unloading response ratio is introduced. Based on acoustic emission analysis, the characteristics of load-unloading response ratio of marble at different stress stages and the applicability of different parameters to denote load-unloading response ratio are analyzed. The characteristics of load-unloading response ratio at original stress point of marble are studied. The main conclusions of this paper are as follows: 1) based on dissipative energy method to characterize damage, the damage evolution curve of marble is "concave" in general. Under the stress loading condition, the damage of marble is characterized by dissipative energy method, and the damage of marble is mainly at the stage of unsteady development of crack. That is to say, the damage of marble is mainly concentrated in the near peak stress stage. (2) the damage is characterized by acoustic emission method, and the damage of marble at loading and unloading stage is considered. The damage evolution curve of marble shows an upward bending pattern. The curve is smooth and shows the signs of nonlinear growth. Both the dissipative energy method and acoustic emission method are more suitable to characterize the damage evolution process of marble, and the acoustic emission method is more suitable than the dissipative energy method. The advantage of the method is that the acoustic emission method can reflect the damage of marble at the unloading stage. Although the dissipative energy method can not characterize the damage at the unloading stage, it can avoid the influence of the quiet period of the acoustic emission on the number of acoustic emission impacts and the ringing count. The load-unloading response ratio of marble characterized by energy Benioff strain is consistent, and the four parameters indicate that the load-unloading response ratio is more consistent. The response ratio of loading and unloading is better than that of acoustic emission impact number, which is characterized by ringing count and energy Benioff strain. The change of load-unload response ratio of marble is more obvious with the increase of stress by means of acoustic emission energy. Numerically, the ratio of load-unloading response of marble is "down-steady rise" with the increase of stress, and the load-unloading response ratio is at a higher level in the initial compaction stage. At the stage of elastic deformation and microelastic fracture stable development, the fluctuation is about 1, and the phenomenon of obvious rise occurs in the stage of unsteady fracture development. This characteristic of marble is helpful to identify the stress state in which it is located. It can provide a certain basis for judging the stability of engineering rock mass. 6) the load-unloading response ratio of the stress point of marble is at a higher level and obviously larger than 1, which is different from loading and unloading in the stage of elastic deformation to fracture stability development. The load response ratio is stable at about 1. In the transition stage of the load-unloading response ratio between "descent and stability", the characteristic of marble can provide a certain basis for the identification of its Kaiser effect points.
【學位授予單位】：江西理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TD313

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