本文選題：預(yù)置裂隙　切入點(diǎn)：壓縮試驗(yàn)　出處：《中國地質(zhì)大學(xué)(北京)》2015年碩士論文

【摘要】：裂隙巖體強(qiáng)度和變形特性受裂隙幾何特征及應(yīng)力條件的影響,其失穩(wěn)破壞也大都是由巖體內(nèi)部裂隙面的擴(kuò)展、匯合貫通引起的。本文以含預(yù)置張開裂隙的純水泥試件作為類巖石材料模擬脆性巖石,通過室內(nèi)單軸壓縮試驗(yàn)和常規(guī)三軸壓縮試驗(yàn),系統(tǒng)地研究裂隙幾何特征(傾角、間距、貫通率、張開度、組數(shù)和形態(tài))及圍壓對裂隙巖體力學(xué)參數(shù)的影響;同時(shí)運(yùn)用Vic-3D非接觸式全場應(yīng)變測量系統(tǒng)和FLAC3D有限元數(shù)值模擬軟件,分析單軸壓縮條件下巖體的裂紋擴(kuò)展規(guī)律。本文主要工作和研究成果如下:(1)裂隙巖體的力學(xué)特性和裂紋擴(kuò)展機(jī)理分析。結(jié)合裂隙幾何特征和巖體破壞過程,對裂隙巖體的力學(xué)本構(gòu)模型和裂紋擴(kuò)展機(jī)理進(jìn)行了理論分析。(2)通過大量單軸壓縮試驗(yàn)和部分三軸壓縮試驗(yàn),研究了不同裂隙幾何特征及圍壓對裂隙試件峰值強(qiáng)度和彈性模量的影響。單軸壓縮條件下,試件峰值強(qiáng)度隨裂隙傾角的變化規(guī)律大致呈V型,彈性模量隨裂隙傾角變化從0°到90°基本呈遞增趨勢,在強(qiáng)度最低點(diǎn)出現(xiàn)輕微回落;圍壓條件下,試件峰值強(qiáng)度和彈性模量隨裂隙傾角的變化規(guī)律與單軸壓縮情況類似,但強(qiáng)度最低點(diǎn)由單軸壓縮時(shí)的45°變?yōu)?0°。通過分析自定義的巖體力學(xué)參數(shù)折減系數(shù)隨裂隙幾何特征變化規(guī)律的擬合函數(shù)曲線,推測巖體力學(xué)參數(shù)對不同裂隙特征的敏感程度從大到小可作如下排列:組數(shù)間距貫通率張開度形態(tài)。從試件破壞形態(tài)來看,單軸壓縮條件下試件多為脆性張拉破壞或拉剪混合破壞;在圍壓條件下試件均為剪切破壞,且殘余強(qiáng)度明顯增大表現(xiàn)出一定的塑性,其中部分試件出現(xiàn)二次破壞現(xiàn)象。(3)借助Vic-3D應(yīng)變測量系統(tǒng)和FLAC3D數(shù)值模擬軟件,分析了試件在單軸加載過程中的裂紋擴(kuò)展規(guī)律。發(fā)現(xiàn)有拉伸裂紋、剪裂紋、翼裂紋與反翼裂紋四種形態(tài)裂紋,且以翼裂紋發(fā)育為主。裂隙尖端應(yīng)力集中引起次生裂紋發(fā)育并沿近似加載方向擴(kuò)展,在相鄰裂隙之間或裂隙與自由面之間匯合貫通切穿巖橋,最終導(dǎo)致試件破壞。
[Abstract]:The strength and deformation characteristics of fractured rock mass are affected by the fracture geometry and stress conditions. The instability and failure of fractured rock mass are mainly caused by the expansion of the fracture plane and the confluence of the rock mass.In this paper, pure cement specimens with prefabricated open fissures are used to simulate brittle rocks. The geometric characteristics of fractures (inclination angle, spacing, penetration ratio, opening degree) are systematically studied by laboratory uniaxial compression test and conventional triaxial compression test.At the same time, Vic-3D non-contact full-field strain measurement system and FLAC3D finite element numerical simulation software are used to analyze the crack propagation law of rock mass under uniaxial compression.The main work and results of this paper are as follows: 1) Analysis of mechanical properties and crack propagation mechanism of fractured rock mass.Based on the geometric characteristics of fracture and the failure process of rock mass, the mechanical constitutive model and crack propagation mechanism of fractured rock mass are theoretically analyzed. (2) A large number of uniaxial compression tests and partial triaxial compression tests are carried out.The effects of different fracture geometry and confining pressure on the peak strength and elastic modulus of fracture specimen were studied.Under uniaxial compression, the variation of peak strength with crack inclination is approximately V-shaped, and elastic modulus increases with fracture inclination from 0 擄to 90 擄, and decreases slightly at the lowest point of strength, and decreases slightly under confining pressure.The variation of peak strength and modulus of elasticity with fracture inclination is similar to that of uniaxial compression, but the lowest point of strength changes from 45 擄to 30 擄under uniaxial compression.By analyzing the fitting function curve of the self-defined parameter reduction coefficient of rock mass with the geometric characteristics of fracture,It is inferred that the sensitivity of mechanical parameters of rock mass to different fracture characteristics can be arranged as follows: group number spacing penetration rate opening shape.According to the failure patterns of the specimens, most of the specimens under uniaxial compression are brittle tensile failure or tensile shear failure, but under confining pressure, the specimens are shearing failure, and the residual strength obviously increases to a certain extent of plasticity.Among them, some specimens appear secondary failure phenomenon. (3) with the help of Vic-3D strain measurement system and FLAC3D numerical simulation software, the crack propagation law of the specimen under uniaxial loading is analyzed.It is found that there are four types of cracks, namely tensile crack, shear crack, wing crack and reverse crack.The stress concentration at the crack tip leads to the development of the secondary crack and its propagation along the approximate loading direction, which leads to the failure of the specimen by connecting and cutting through the rock bridge between the adjacent cracks or between the fissure and the free surface.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU45

【參考文獻(xiàn)】

相關(guān)期刊論文 前5條

1 黃明利,唐春安,梁正召;巖石裂紋相互作用的應(yīng)力場分析[J];東北大學(xué)學(xué)報(bào);2001年04期

2 白世偉,任偉中,豐定祥,陳錦清,賈中和;平面應(yīng)力條件下閉合斷續(xù)節(jié)理巖體破壞機(jī)理及強(qiáng)度特性[J];巖石力學(xué)與工程學(xué)報(bào);1999年06期

3 夏才初;李宏哲;劉勝;;含節(jié)理巖石試件的卸荷變形特性研究[J];巖石力學(xué)與工程學(xué)報(bào);2010年04期

4 任建喜,惠興田;裂隙巖石單軸壓縮損傷擴(kuò)展細(xì)觀機(jī)理CT分析初探[J];巖土力學(xué);2005年S1期

5 仝興華;韓建新;李術(shù)才;李樹忱;楊為民;;基于裂隙巖樣的多組貫穿裂隙巖體峰后應(yīng)力-應(yīng)變曲線研究[J];巖土力學(xué);2013年07期

，

本文編號：1718182