Experimental Research And Engineering Application Of The Artificially Frozen Soil Dynamic Constitutive Model

This paper obtained the artificially frozen clay deformation law under dynamic loads by the laboratory study, derivation of the artificially permafrost dynamic load constitutive relations met the improvement Xi-Yuan model based on the experimental results, and Verified the correctness of the dynamic load of frozen soil constitutive model by the field test of the frozen wells tower foundation.Adopted the Sine wave to simulate the enhance loads deformation law of the frozen wells tower foundation. Factors considered in the pilot program:take the artificially permafrost vibration frequency0.2Hz,0.4Hz,0.6Hz; freezing temperatures:-5℃,-10℃,-15℃; confining pressure:0.5MPa,1.0MPa,1.5MPa, a total of81groups. Through the orthogonal method, only nine can no repeat the completion of the pilot project content. The obtained conclusions were as follows:The dynamic elastic modulus of the permafrost affected by temperature under dynamic loads; the dynamic elastic modulus decreased as the temperature increasing, and increased with the temperature decreasing, an increase of about:1OMPa/℃. The dynamic elastic modulus ups and downs with the confining pressure, and increased with the vibration frequency increasing, reaching0.25MPa/Hz; it increased with the increase of the dynamic strain, about0.05MPa/%.The dynamic shear modulus increased with the increasing confining pressure, and decreased with the load vibration number increasing, linearly increased with the decreasing temperature, an increase of150MPa/℃. The permafrost dynamic damping ratio increased with the strain amplitude and confining pressure increased, rapidly smaller as the temperature decreased, and reduced with the increased load vibration frequency.The dynamic creep curve of the frozen clay was divided into three stages:the steady creep stage, the decay creep stage and accelerated creep stage. The permafrost dynamic creep constitutive model is formed by the combination of rheological components of the elastic components, visco-elastic components, visco-plastic components. This article in accordance with the dynamic triaxial test results of the artificially frozen soil, based on the dynamics, continuum mechanics and frozen soil mechanics principles, established the creep constitutive model of the artificially frozen soil under cyclic loading, that was the elastic-viscoelastic-viscoplastic constitutive model, and proposed the model parameters determine methods, to derive the elastic strain flexibility matrix, the viscoplastic strain flexibility matrix, and embedded into the large-scale numerical simulation software ADINA, and fitting the results with the experimental, the results showed that the fitted values were in good agreement with the measured values.This paper rely on the well tower-foundation engineering test of the Huainan Gubei mine, using the proposed elastic-viscoelastic-viscoplastic dynamic constitutive model and the parameter determine methods to do the numerical calculation on the well tower-foundation, the results showed that the theoretical calculation of the frozen wall displacement met the measured displacement transformation law, and the value errors were in the allowable range. The results indicated that using the elastic viscoelastic-viscoplastic dynamic constitutive model theoretical calculations to obtain the frozen wall stress and displacement field was reasonable.