常用假设下黏弹组合模型两类表述参数间转换及适用性

Conversion between Two Types of Parameters in the Viscoelastic Combination Model for Common Hypotheses and Its Applicability

黏弹性组合模型通常有两类表述,一类为基于拉压模量和拉压黏性系数的表述,另一类为基于剪切模量和剪切黏性系数的表述.对于广义Kelvin模型,这两类表述参数间的转换已经建立.但存在理论基础较薄弱、转换的适用范围和适用条件不够明确的问题.从线黏弹性理论出发,考虑岩土工程两种常用的三维假设(常泊松比假设和常体积模量假设),给出了这些假设下黏弹性组合模型蠕变柔量及其复柔量在两类表述之间的转换关系,然后将其应用于广义Kelvin模型和Poynting-Thomson模型,分别推导出了两个模型在两类表述参数间的转换公式,明确了参数转换的适用范围和适用条件,以及应用于实际工程时须注意的问题.

The viscoelastic combination model usually has two forms: one based on Young’s modulus and the coefficients of tensile viscosity, the other based on shear modulus and the coefficients of shear viscosity. The conversion relationship between these two types of parameters has been established for the generalized Kelvin model. However, there still exist some problems. For instance, the theoretical foundation is still relatively weak, and the scope and conditions of application are not clear. Considering two kinds of three-dimensional hypothesis commonly used in geotechnical engineering(i.e., constant Poisson’s ratio hypothesis and constant volume modulus hypothesis), the conversion relationship between two types of parameters for creep compliance and complex compliance in the viscoelastic model is given based on the theory of linear viscoelasticity. Then the conversion relationship is applied to the generalized Kelvin model and the Poynting-Thomson model, and the conversion formulas between two types of parameters for these two models are established respectively. The scope and conditions of application for the conversion are put forward, and the problems that need attention in practical engineering application are pointed out in the end.