基于矩张量的含孔洞砂岩声发射特性模拟研究

    DEM Simulation on the AE Characteristics of Sandstone Containing Hole under Different Filling Conditions Based on Moment Tensors

    • 摘要: 充填物对岩土工程结构稳定性有显著影响,使得含孔洞岩体结构失稳破坏的出现不确定性。为了探究充填孔洞岩体在受载时的声发射响应机制,本研究采用离散元法和矩张量理论对不同充填条件下的含孔洞砂岩进行单轴压缩数值模拟,分析破坏过程中的声发射事件类型、幅值分布和b值特征。结果表明:(1)在充填条件b、c下,圆形、矩形和梯形试样的强度增长率分别为2.75%、7.12%、4.35%和8.30%、13.14%、18.03%;(2)充填物的加入使试样声发射更为剧烈,且剧烈程度与充填物强度正相关,充填试样的声发射累计数和声发射率均高于未充填试样;(3)在充填c条件下,剪切型声发射占比高于其他充填条件,声发射频数-幅值呈正态分布;(4)在相同充填条件下,圆形孔洞的声发射b值最大,其次为矩形孔洞和梯形孔洞;在相同孔洞形状下,充填c条件下的b值最小,充填a条件下的b值最大。研究结果可为工程中不同充填条件下含孔洞岩体的声学破坏特征分析提供一定的参考。

       

      Abstract: The filling material significantly affects the structural stability of geotechnical engineering, which makes the occurrence of instability and failure of rock mass structure with holes uncertain. To explore the acoustic emission response mechanism of sandstone containing hole under different filling conditions under loading, the discrete element method and moment tensor theory were used to simulate the uniaxial compression of sandstone with holes under different filling conditions, and the types, amplitude distribution and b-value characteristics of acoustic emission events in the failure process were analyzed in this study. The results show that: (1) under filling conditions b and c, the strength growth rates of circular, rectangular, and trapezoidal specimens are 2.75%, 7.12%, 4.35%, and 8.30%, 13.14%, 18.03%, respectively; (2) the addition of filling material leads to more intense AE events, with the intensity of AE activity positively correlated with the strength of the filling material. The cumulative number of AE events and AE rate of filled specimens are higher than those of unfilled specimens; (3) under filling condition c, the proportion of shear-type AE events is higher than that in other filling conditions, and the AE frequency-amplitude distribution follows a normal distribution; (4) under the same filling condition, the AE b value of circular hole sample is the largest, followed by rectangular and trapezoidal holes. Under the same hole shape, the b value is the smallest under the condition of filling c, and the b value is the largest under the condition of filling a. The findings can provide some reference for the analysis of acoustic failure characteristics of rock mass with holes under different filling conditions in engineering.

       

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