一个描述软黏土时效特性的一维弹黏塑性模型

为了描述软黏土一维应力-应变关系的时效特性，基于Bjerrum的等时间线体系，提出等黏塑性应变率线概念，推导了黏塑性应变率与黏塑性应变增量的关系，建立了软黏土的一维弹黏塑性模型；从理论上分析了新建模型与3种典型的一维弹黏塑性时效本构模型的内在联系，表明新建模型与其他3种模型在本质上是等效的，且形式更简洁，物理意义更明确；利用新建模型对软黏土的固结-蠕变耦合效应、应变率效应、应力松弛效应等时效特性进行了理论分析，并得到了相应的解析解；结合宁波软黏土的一维固结试验，阐述了模型参数的确定方法，并用新建模型对宁波软黏土的固结-蠕变试验、温州软黏土的一维多级等应变率试验、香港海相软黏土的一维应力松弛试验进行模拟，验证了新建模型的有效性。研究结果表明，新建模型能很好地模拟软黏土的一维时效特性。

A one-dimensional elasto-viscoplastic model for describing time-dependent behavior of soft clays

The purpose of this study is to present the development of a 1D elasto-viscoplastic (1DEVP) constitutive model to describe the time-dependent behavior of soft clays. Firstly, based on Bjerrum’s concept of time lines, a new concept of viscoplastic strain rate lines is proposed, and after the relationship between viscoplastic strain rate and viscoplastic strain increment is deduced, the 1DEVP model for soft clays is established. Secondly, the relationship between the newly developed model and other three well-known elasto-viscoplastic(EVP) constitutive models are theoretically discussed. It demonstrated that the new model with no essential difference from the other three EVP models is simpler in form and clearer in physical meaning than others. Thirdly, the established 1DEVP is used to develop analytical solutions for consolidation-creep coupling effect, strain rate effect, stress relaxation effect. Lastly, based the one-dimensional consolidation tests on Ningbo soft clays, the model parameters is calibrated. Furthermore, the model is used to simulate 1D consolidation-creep tests on Ningbo soft clays, 1D staged constant rates of strain tests on Wenzhou soft clays and 1D relaxation tests on Hongkong marine clays. The comparisons between experimental results and simulations show that the newly proposed 1DEVP model has a good predictive ability for the one-dimensional time-dependent behavior of soft clays.