Burgers力学元件蠕变模型由于其简洁的数学形式,目前广泛应用于冻土工程的蠕变计算中。力学元件模型的计算准确性很大程度上取决于模型参数获取方法的准确性。现阶段采用Burgers模型的蠕变计算分析工作大多是基于“试错法”原理进行蠕变参数的确定,该方法缺乏明确的物理意义,从而大大降低了模型的可靠性。本文以冻结粉质黏土为试验对象,开展了不同温度和轴向压力条件下的单轴蠕变试验。结合Burgers蠕变模型和不同条件下的蠕变应变试验数据提出了根据物理意义标定参数的方法,Maxwell弹性剪切模量GM是通过施加荷载时的瞬时应变来计算的;Maxwell粘滞系数HM取决于蠕变应变曲线上直线段的斜率;Kelvin弹性剪切模量GK可以根据直线段延长线与应变轴的交点来确定;Kelvin粘滞系数HK则可以通过蠕变应变曲线上蠕变应变率非线性减小段的某一点的应变和时间来计算。该方法的提出为参数的确定提供了理论基础,与“试错法”相比,该方法更加科学直观且提高了参数确定的准确性和效率。通过对比分析试验结果与计算结果表明,Burgers模型的计算结果能够准确描述冻土蠕变的衰减和稳定发展蠕变阶段。这说明本文提出的Burgers模型参数确定方法是有效的。
The Burgers mechanical creep model is extensively used in frozen soil engineering for its concise mathematical formulation. The accuracy of this model's calculations significantly depends on the precision with which its parameters are determined. The current practice of using the “trial and error” method to ascertain these parameters often lacks clear physical rationale, thus undermining the model's reliability. This paper presents a study on frozen silty clay under various temperatures and axial pressures, employing uniaxial creep tests to refine the parameter determination process. By integrating the Burgers model with empirical data, the physical significance of its parameters is delineated: the Maxwell elastic shear modulus GM is derived from the instantaneous strain upon loading, the Maxwell viscosity coefficient HM is based on the slope of the linear section of the creep curve, the Kelvin elastic shear modulus GK is ascertained from the intersection of the linear section's extension with the strain axis, and the Kelvin viscosity coefficient HK is calculated from a specific point on the nonlinear deceleration phase of the creep curve. This approach circumvents the limitations of the traditional trial-and-error method, offering a theoretical foundation for parameter determination that is more scientific, intuitive, and efficient. Comparative analysis of experimental and computational outcomes confirms the Burgers model's efficacy in accurately depicting the attenuation and stable progression phases of frozen soil creep. This validation suggests that the parameter determination method proposed in this study is effective.
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