發(fā)布時間：2018-05-15 13:37

  本文選題：巖石力學 + 單軸壓縮�。� 參考：《巖石力學與工程學報》2017年05期

【摘要】：采用聲波、聲發(fā)射一體化裝置,研究單軸壓縮下花崗巖波速與聲發(fā)射演化規(guī)律,通過宏細觀方法確定各應力門檻值,研究裂紋擴展不同階段聲發(fā)射演化及波傳播規(guī)律。結果表明:細觀裂紋的演化與宏觀變形直接對應,由于微裂紋主要沿軸向擴展,導致軸向剛度對裂紋起裂及貫通的敏感度弱于非線性增長的側向變形,瞬時泊松比曲線斜率變化點與應力門檻值對應,聲發(fā)射測試確定的起裂應力比宏觀應變法偏小,但反映了微裂紋的初始萌生;采用實測波速變化分析聲發(fā)射震源的時空及幅值演化分布,較好地描繪了裂紋的擴展過程,由于不同階段聲發(fā)射信號的幅值及能量存在差異,導致聲發(fā)射特征參數(shù)演化規(guī)律差異較大(尤其在損傷應力之后),AE能量在破壞前呈突發(fā)性增長,可作為災害性破壞的前兆;加載初始階段,由于微裂隙的閉合,波速及波幅均隨應力逐漸增大,但增加速率逐漸下降,側向波速在閉合應力附近基本達到峰值,此后一定階段基本保持不變,但其他方向波速則繼續(xù)增大,隨著波傳播方向與徑向夾角的增大,波速增加幅度及波速下降點對應的應力(損傷應力前、后)逐漸增大,峰值應力附近對應波速下降幅度減小;波速受損傷演化的影響要滯后于聲發(fā)射事件。
[Abstract]:The acoustic wave velocity and acoustic emission evolution law of granite under uniaxial compression are studied by means of acoustic wave and acoustic emission integrated device. The stress threshold values are determined by macroscopical method, and the acoustic emission evolution and wave propagation in different stages of crack propagation are studied. The results show that the evolution of microcracks corresponds directly to the macroscopic deformation. Because the microcracks are mainly propagated along the axial direction, the sensitivity of axial stiffness to crack initiation and penetration is weaker than that of nonlinear lateral deformation. The slope change point of the instantaneous Poisson's ratio curve corresponds to the stress threshold. The initial crack stress determined by acoustic emission test is smaller than that determined by macroscopic strain method, but it reflects the initial initiation of microcracks. The time-space and amplitude evolution distribution of acoustic emission source is analyzed by using the measured wave velocity variation, and the crack propagation process is well described. Due to the difference of amplitude and energy of acoustic emission signal in different stages, As a result, the evolution law of acoustic emission characteristic parameters is different (especially after the damage stress, the energy of AE increases suddenly before failure, which can be used as a precursor of disastrous damage, and at the initial stage of loading, because of the closure of microfracture, the energy of AE increases suddenly before failure. The wave velocity and amplitude increase gradually with the stress, but the increasing rate decreases gradually, and the lateral wave velocity reaches the peak value near the closed stress, after which the wave velocity remains basically unchanged, but the other directional wave velocities continue to increase. With the increase of the angle between the direction of wave propagation and the radial angle, the amplitude of wave velocity increase and the stress corresponding to the drop point of wave velocity (before and after the damage stress) increases gradually, and the corresponding amplitude of wave velocity decreases near the peak stress. The influence of damage evolution on wave velocities lags behind acoustic emission events.
【作者單位】： 中國科學院武漢巖土力學研究所巖土力學與工程國家重點實驗室;南京理工大學機械工程學院;
【基金】：國家自然科學基金重點項目(51439008);國家自然科學基金面上項目(41572307);國家自然科學基金青年科學基金項目(51209200)~~
【分類號】：TU45

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