本文關(guān)鍵詞：巖石斷裂表面細(xì)觀接觸演化與剪切力學(xué)模型研究　出處：《北京科技大學(xué)》2016年博士論文　論文類型：學(xué)位論文

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【摘要】：巖體的抗剪強(qiáng)度和長期穩(wěn)定性在很大程度上取決于巖石斷裂粗糙面細(xì)觀接觸與破壞力學(xué)行為。為從細(xì)觀層面探究斷裂巖體粗糙表面接觸狀態(tài)與抗剪強(qiáng)度關(guān)系,采用剪切蠕變實(shí)驗(yàn)方法對壓剪破壞和拉破壞兩類斷裂巖石的接觸和剪切力學(xué)行為進(jìn)行研究。借助激光掃描、聲發(fā)射和CT檢測等方法,揭示剪切過程中巖石粗糙表面凹凸體磨損過程、表面微孔洞微裂紋生長發(fā)育趨勢、表面接觸損傷演化等微觀破壞機(jī)理以及宏觀力學(xué)特征。針對巖體粗糙斷裂面不連續(xù)接觸的特點(diǎn),提出表征斷裂巖體表面接觸的分形公式,建立了巖石節(jié)理的接觸力學(xué)模型,為刻畫和描述巖體斷裂面細(xì)觀接觸演化過程與宏觀力學(xué)行為提供了基礎(chǔ)理論依據(jù)。論文取得的主要研究成果如下：(1)定量分析和研究了巖石斷裂面形貌的細(xì)觀特征。制作了壓剪和拉伸兩類巖石斷裂面,運(yùn)用激光精細(xì)掃描技術(shù),重構(gòu)了斷裂巖石表面形貌：采用分形理論,對巖石斷裂表面的起伏度和粗糙度進(jìn)行了定量分析。(2)通過直接剪切蠕變實(shí)驗(yàn),研究了斷裂巖石的宏觀力學(xué)行為。對斷裂巖樣進(jìn)行分級(jí)加載剪切蠕變實(shí)驗(yàn),得到了斷裂巖石剪切蠕變實(shí)驗(yàn)中的位移、抗剪強(qiáng)度等,從巖樣斷裂面形成機(jī)制出發(fā),揭示出兩類斷裂巖樣在剪切蠕變條件下的宏觀力學(xué)特性。(3)通過“CT切層法”,揭示了兩類斷裂巖石剪切蠕變破壞模式。斷裂巖石在剪切蠕變作用下的破壞模式主要有：斷裂面之間的剪切摩擦破壞、微小凹凸體的磨損、剪斷、遷移,以及亞表面裂隙的萌生或翼裂紋發(fā)育等,展示了斷裂巖石剪切蠕變前后巖石斷裂面細(xì)觀結(jié)構(gòu)和空間展布形態(tài)、斷裂巖石內(nèi)部三維損傷情況。(4)利用聲發(fā)射得到斷裂巖石在剪切蠕變過程中和失穩(wěn)前聲發(fā)射頻率和能量特征。拉破壞巖樣的聲發(fā)射能量波峰出現(xiàn)在蠕變中后期；壓剪破壞巖樣聲發(fā)射能量在蠕變中期出現(xiàn)低谷。通過對斷裂面在剪切蠕變過程中聲發(fā)射定位,發(fā)現(xiàn)巖石斷裂面聲發(fā)射具帶狀分布特征。(5)對巖石斷裂面接觸區(qū)域內(nèi)不同高度剖面上的接觸形態(tài)分布進(jìn)行廠分析。研究表明：拉破壞斷裂巖樣雙翼接觸狀態(tài)呈離散“群島式”接觸,壓剪斷裂試樣在剪切蠕變過程中接觸形態(tài)為不規(guī)則“海岸式”接觸。得到斷裂面接觸狀態(tài)的變化,建立了接觸面積與巖石抗剪強(qiáng)度的關(guān)系。(6)利用分形幾何、接觸力學(xué)等方法,建立丫斷裂巖體在壓剪載荷作用.下斷裂面接觸的分形模型。斷裂粗糙面接觸隨著法向力變化產(chǎn)生動(dòng)態(tài)演化,接觸面積和接觸分形維數(shù)隨法向力增大而增加,壓剪斷裂巖樣斷裂面的接觸多為大片起伏面之間的接觸,拉破壞斷裂巖樣斷裂面的接觸多為小微凸體散點(diǎn)狀接觸。得到巖石斷裂面接觸過程中分形維數(shù)的變化規(guī)律,建立了壓剪載荷與接觸分形維數(shù)之間的關(guān)系,并由實(shí)驗(yàn)得到初步驗(yàn)證。
[Abstract]:The shear strength and long-term stability of rock mass depend to a great extent on the meso-contact and destructive behavior of rock fracture rough surface. The contact and shear mechanical behaviors of two types of fracture rocks were studied by means of shear creep test method, laser scanning, acoustic emission and CT detection. It is revealed that the wear process of the rough surface of rock during shear and the trend of the growth and development of micropores and microcracks on the surface. According to the characteristics of discontinuous contact on the rough fracture surface of rock mass, a fractal formula is proposed to characterize the surface contact of fractured rock mass. The contact mechanics model of rock joints is established. This paper provides a basic theoretical basis for describing the evolution process of mesoscopic contact and macroscopic mechanical behavior of rock fracture surface. The main research results obtained in this paper are as follows: 1). The microcosmic characteristics of rock fracture surface were quantitatively analyzed and studied. Two kinds of rock fracture surfaces, compression shear and tension, were made. The surface morphology of fractured rock was reconstructed by using laser fine scanning technique. By means of fractal theory, the fluctuation and roughness of rock fracture surface were quantitatively analyzed by means of direct shear creep experiment. In this paper, the macroscopic mechanical behavior of fractured rock is studied. The displacement, shear strength and so on in the shear creep test of fractured rock are obtained by means of graded loading shear creep experiment, and the formation mechanism of fracture surface of rock sample is discussed. The macroscopic mechanical properties of two kinds of fracture rock samples under shear creep condition are revealed. Two kinds of shear creep failure modes of fracture rock are revealed. The failure modes of fracture rock under shear creep include: shear friction failure between fracture surfaces, wear of tiny concave convex body, shear fracture and migration. As well as the initiation of sub-surface cracks or the development of wing cracks, it shows the meso-structure and spatial distribution of fracture surface before and after shear creep. Three-dimensional damage in fractured rock. The acoustic emission frequency and energy characteristics of fractured rock during shear creep and before instability are obtained by acoustic emission. The peak of acoustic emission energy of tensile failure rock appears in the middle and late period of creep. The acoustic emission energy of compression shear failure rock samples is low in the middle of creep. The acoustic emission of fracture surface is located during shear creep process. It is found that the acoustic emission of rock fracture surface has zonal distribution characteristics. The distribution of contact morphology at different heights in the contact area of rock fracture surface is analyzed in a factory. The results show that the contact state of the two wings of tensile failure rock is discrete "archipelagic" contact. The contact form of compressive shear fracture specimen is irregular "coastal" contact during shear creep, and the change of contact state of fracture surface is obtained. The relationship between contact area and shear strength of rock is established. (6) Fractal geometry, contact mechanics and other methods are used. The fractal model of contact between fracture surface and fracture surface is established. The contact area and fractal dimension increase with the increase of normal force, and the contact area and fractal dimension increase with the change of normal force. The contact of compression shear fracture rock sample fracture surface is mostly the contact between a large area of undulating surface. The contact of fracture surface of tensile failure rock sample is mostly small microconvex scattered point contact. The change rule of fractal dimension in contact process of rock fracture surface is obtained, and the relationship between compressive shear load and contact fractal dimension is established. The experimental results are preliminarily verified.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：O346.1

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相關(guān)期刊論文 前1條

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本文編號(hào)：1359509