本文關(guān)鍵詞： 位移不連續(xù)模型 臨界厚度 頻散特性 黏性衰減 參數(shù)正演　出處：《江西理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：為快捷獲取巖土體巖性參數(shù),在德興銅礦、雙旗山金礦采空區(qū)選取巖體發(fā)育較好、巖性完整的邊坡面進(jìn)行波動法現(xiàn)場測試,研究應(yīng)力波在節(jié)理巖體中的傳播規(guī)律,基于波形變化測試巖體變形參數(shù),并與鉆孔彈模儀的測試結(jié)果進(jìn)行比較,研究結(jié)果如下:(1)將節(jié)理面視為Kelvin黏彈性介面,考慮節(jié)理質(zhì)量對應(yīng)力波傳播的影響,運(yùn)用波的位移位函數(shù)得到諧波在厚黏彈性節(jié)理的透、反射系數(shù)計算公式,采用波形相關(guān)系數(shù)描述子波穿過黏彈性節(jié)理的波形變化,討論具有一定厚度的黏彈性節(jié)理采用位移不連續(xù)模型計算的適用條件。設(shè)厚黏彈性節(jié)理模型和位移不連續(xù)模型的透射波波形相關(guān)系數(shù)為0.9時對應(yīng)的節(jié)理厚度為臨界厚度。采用簡化的位移不連續(xù)模型描述巖體節(jié)理面,基于波形變化系數(shù)最小的原則,確定節(jié)理面力學(xué)參數(shù)行之有效的方法。巖體與節(jié)理的阻抗比對臨界厚度的影響很小;臨界厚度隨子波中心頻率增大成負(fù)指數(shù)減小;入射角越大,臨界厚度隨中心頻率減小得越慢。當(dāng)節(jié)理厚度為0.03m時,采用位移不連續(xù)模型和厚黏彈性模型計算得到節(jié)理力學(xué)參數(shù)非常接近;隨節(jié)理厚度和子波中心頻率增加,運(yùn)用位移不連續(xù)模型的計算結(jié)果偏差越大。實驗結(jié)果與理論分析是一致的。(2)巖體黏滯性作用對應(yīng)力波傳播影響主要體現(xiàn)為速度頻散和幅值衰減兩方面。前者體現(xiàn)為應(yīng)力波傳播相速度因頻率而變化,將巖體視為Kelvin黏彈性介質(zhì),運(yùn)用傅立葉級數(shù)對測點(diǎn)實測波形進(jìn)行展開,根據(jù)應(yīng)力波傳過黏彈性巖體時相位的變化特征,來研究相速度的頻散特性。其中,級數(shù)展開時,諧波次數(shù)對波形分解影響極大,取n=300足夠滿足計算需要。假設(shè)介質(zhì)黏性系數(shù)非定常的表達(dá):η=a0f q,基于P波的傳播規(guī)律計算得到參數(shù)a0=1007600,q=0.136,當(dāng)頻率f=300Hz時,計算得到黏性系數(shù)η=2.189MPa?s;基于SV波的傳播規(guī)律計算得到參數(shù)a0=702861,q=0.321,當(dāng)頻率f=300Hz時,計算得到黏性系數(shù)η=4.386MPa?s。(3)將巖體介質(zhì)視為Kelvin半無限體,根據(jù)應(yīng)力波黏性衰減理論,擬合P波振幅隨傳播距離的衰減系數(shù),計算得到巖體彈性模量為E=3.27GPa;擬合SV波振幅隨傳播距離的衰減系數(shù),計算得到巖體彈性模量為E=3.22GPa;采用鉆孔彈模儀測試得到巖體彈性模量為2.46GPa,動力法測試巖體彈性模量是靜力法1.33倍。假設(shè)介質(zhì)黏性系數(shù)非定常的表達(dá):η=a0f q,基于P波的傳播規(guī)律計算得到巖體黏性系數(shù)初值a0=7341,陡度參數(shù)q=0.509;基于SV波傳播規(guī)律計算得到初值系數(shù)a0=315000.8,陡度參數(shù)q=0.249。
[Abstract]:In order to obtain the lithologic parameters of rock and soil quickly, the rock mass developed well in the goaf of Shuangqishan Gold Mine is selected in Dexing Copper Mine, and the slope surface with intact lithology is tested by wave method. The propagation law of stress wave in jointed rock mass is studied, and the deformation parameters of rock mass are measured based on waveform change, and the results are compared with those of borehole elastic modulus meter. The results are as follows: (1) considering the effect of the mass of the joint on the propagation of force wave, the harmonic permeation of thick viscoelastic joints is obtained by using the displacement potential function of the wave, which regards the joint surface as the Kelvin viscoelastic interface, and considers the effect of the mass of the joint on the propagation of the force wave. The wave correlation coefficient is used to describe the waveform change of wavelet passing through viscoelastic joints. The suitable conditions for calculating viscoelastic joints with certain thickness by displacement discontinuity model are discussed. The thickness of joints corresponding to thick viscoelastic joint model and displacement discontinuity model is given when the correlation coefficient of transmission wave waveform is 0.9. For critical thickness, a simplified discontinuous displacement model is used to describe the joints of rock mass. Based on the principle of minimum waveform variation coefficient, an effective method for determining mechanical parameters of joints is proposed. The impedance ratio of rock mass to joint has little effect on critical thickness. The critical thickness decreases exponentially with the increase of the center frequency of the wavelet. When the thickness of joints is 0.03m, the mechanical parameters of joints obtained by displacement discontinuity model and thick viscoelastic model are very close. It increases with the thickness of joints and the frequency of wavelet center. The greater the deviation of the calculated results from the discontinuous displacement model is, the more consistent the experimental results are with the theoretical analysis. The effect of viscous rock mass on wave propagation is mainly reflected in two aspects: velocity dispersion and amplitude attenuation. The former shows that the phase velocity of stress wave varies with frequency. The rock mass is regarded as a Kelvin viscoelastic medium, and the measured waveform is expanded by Fourier series, and the phase change characteristics of the viscoelastic rock mass are obtained according to the stress wave propagation over the viscoelastic rock mass. In order to study the dispersion characteristics of phase velocity, the number of harmonics has a great influence on the waveform decomposition when the series is expanded. If the unsteady expression of the viscosity coefficient of the medium is assumed: 畏 _ 0 a _ 0f _ Q, the parameter a _ (0) _ (1007600) is calculated based on the propagation law of P wave. When the frequency is 300 Hz, the viscosity coefficient 畏 is calculated to be 2. 189 MPa? Based on the propagation law of SV wave, the parameter a0o / 702861QN / 0.321 is obtained, and the viscosity coefficient 畏 = 4.386MPa / a is calculated when the frequency is 300 Hz. According to the theory of stress wave viscosity attenuation, the attenuation coefficient of P wave amplitude with propagation distance is fitted. The elastic modulus of rock mass is calculated to be E ~ (3. 27) GPA; By fitting the attenuation coefficient of SV wave amplitude with propagation distance, the elastic modulus of rock mass is calculated to be E ~ (3. 22) GPA; The elastic modulus of rock mass measured by borehole elastic modulus instrument is 2.46 GPA, and the elastic modulus of rock mass measured by dynamic method is 1.33 times that of static method. Based on the propagation law of P-wave, the initial value of viscosity coefficient of rock mass, a _ 0 ~ 7341, and the steepness parameter Q ~ (0.509) are obtained. Based on the propagation law of SV wave, the initial coefficient a015000.8 and the steepness parameter qn 0.249 are obtained.
【學(xué)位授予單位】：江西理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU45

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