四川盆地红层砂泥岩循环加卸载动力学特性研究

STUDY ON DYNAMIC CHARACTERISTICS OF SAND AND MUDSTONE IN RED BED IN SICHUAN BASIN UNDER CYCLIC LOADING AND UNLOADING CONDITIONS

  • 摘要: 四川地震多发,广泛分布于该区域的红层岩石的动力学是许多重大工程建设和运营安全的重要影响因素。因此,本文针对3种典型红层砂泥岩(粉砂质泥岩、泥质粉砂岩和细砂岩),开展了不同动应力幅值的单轴循环加卸载试验,结果表明:在相同动应力幅值下,粉砂质泥岩与细砂岩的滞回环相对面积、阻尼比、阻尼系数及泥质粉砂岩的滞回环相对面积、阻尼比均随着循环周次呈对数递减,而泥质粉砂岩的阻尼系数随着循环周次呈开口向下的二次多项式分布;在相同循环周次下,随着应力幅值增大,滞回环相对面积均呈指数递增,粉砂质泥岩和泥质粉砂岩的阻尼比呈指数递增,阻尼系数呈开口向下的二次多项式分布,细砂岩的阻尼比和阻尼系数均呈对数递减。

     

    Abstract: Sichuan is an earthquake-prone area, so the dynamics of red bed rock widely distributed in this area is an important factor affecting the construction and operation safety of many major projects. Therefore, in this paper, a series of uniaxial cyclic loading and unloading tests with different dynamic stress amplitudes were carried out on the three typical red bed sand and mudstones (silty mudstone, argillaceous siltstone and fine sandstone). The results show that: under the same dynamic stress amplitude, the relative area of hysteresis loop, damping ratio and damping coefficient of the silty mudstone and fine sandstone and that of the argillaceous siltstone decrease logarithmically with the cycle times, while the damping coefficient of the argillaceous siltstone shows an open downward quadratic polynomial distribution with the cycle times. In the same cycle, the relative area of hysteresis loop increases exponentially with the increase of stress amplitude, the damping ratio of silty mudstone and argillaceous siltstone increases exponentially, the damping coefficient is a quadratic polynomial distribution in the downward direction of the opening, and the damping ratio and damping coefficient of fine sandstone are logarithmic decreasing.

     

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