分级循环加卸载下大理岩损伤及声发射特性研究

发布时间：2018-02-28 13:53

本文关键词： 大理岩分级循环加卸载损伤声发射加卸载响应比　出处：《江西理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：金属矿山实际地下生产作业中,地下岩体受力状态并不稳定,受地压活动及人工扰动的影响,岩体处于频繁加载及卸载状态。为充分了解大理岩在循环加卸载下损伤及声发射特性,本文以现场及室内试验为基础,探讨了耗散能法及声发射法表征大理岩损伤的适用性与差异性;引入加卸载响应比理论,基于声发射分析了大理岩在不同应力阶段加卸载响应比特征及不同参数表征加卸载响应比的适用性;结合大理岩原岩应力值,研究了大理岩原始应力点加卸载响应比特征。综合上述研究内容,本文主要结论如下:(1)基于耗散能法表征损伤,大理岩损伤演化曲线总体呈“上凹”状,濒临峰值应力前大理岩损伤变量增大非常明显。说明在应力加载条件下,基于耗散能法表征大理岩损伤,大理岩损伤主要在裂纹非稳定发展阶段,即大理岩损伤主要集中在临近应力峰值阶段。(2)基于声发射法表征损伤,同时考虑了大理岩在加载和卸载阶段的损伤,大理岩损伤演化曲线呈现出向上弯曲形态,曲线较为平滑且表现出非线性增长迹象。(3)耗散能法与声发射法均较适于表征大理岩的损伤演化过程。声发射法与耗散能法相比,其优势在于声发射法可反映出大理岩在卸载阶段的损伤状况。耗散能法虽不能表征卸载阶段的损伤,但能避免声发射平静期的影响。(4)声发射撞击数、振铃计数、能量、Benioff应变表征的大理岩加卸载响应比所呈现的规律一致,四种参数表征加卸载响应比具有较高的一致性。振铃计数、能量、Benioff应变所表征加卸载响应比优于声发射撞击数,以声发射能量表征大理岩加卸载响应比随应力的增加变化幅度更为明显,在数值上表现更为灵敏。(5)大理岩随着应力的增加加卸载响应比总体表现为“下降-平稳-升高”。加卸载响应比在初始压密阶段处于较高水平,在弹性变形及微弹性裂隙稳定发展阶段基本在1左右波动,进入非稳定破裂发展阶段出现明显升高的现象,大理岩这一特征有助于识别其所处应力状态,可为工程岩体的稳定性判别提供一定的依据。(6)大理岩原岩应力点所对应的加卸载响应比处在较高水平且明显大于1,有别于其在弹性变形至裂隙稳定发展阶段加卸载响应比稳定在1左右这一现象,处于加卸载响应比“下降-平稳”间的过渡阶段,大理岩这一特征可为其Kaiser效应点的识别提供了一定的依据。
[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.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD313

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