Creep model of over-consolidated soft clay under plane strain

Abstract

通過對原狀軟土進行平面蠕變實驗, 研究平面變形條件下超固結軟黏土的蠕變特征。 研究結果表明, 研制的量測裝置能獨立量測平面應變超固結軟土的側向變形, 可規避實驗過程體積變形測量精度對側向變形數據的影響; 軟土的側向變形與超固結剪應力比OCR_q具有良好的對應關系, OCR_q能同時反映剪應力和應力歷史對軟土側向變形的影響。 平面應變狀態下體積蠕變系數和軸向蠕變系數均與OCR_q有一一對應關系, 依據不同主應力比下的超固結軟土平面變形蠕變實驗, 建立以主應力比和超固結剪應力比為變量的四參數經驗模型。 所建經驗模型包含軟土的正常固結狀態, 可合理反映了主應力比和應力歷史對平面變形軟土蠕變過程的影響。 The creep behavior of over-consolidated soft clay was studied through plane strain tests for undisturbed soft clay using a new measuring device. The results show that the new measuring device can measure the lateral deformation of over-consolidated soft soil under plane strain and eliminate the influence of the accuracy in volumetric deformation measurement. There is a good correlation between the lateral deformation and the over-consolidation shear stress ratio (OCRq), and the OCRq reflects the effects of shear stress and stress history on the lateral deformation. Both the volumetric creep coefficient and the axial creep coefficient have a good correlation with the OCRq. On the basis of the plane strain creep tests to the over-consolidated soft soil under different principal stress ratios, an empirical model with four parameters was developed. The variables in the model are the principal stress ratio and OCRq. The empirical model takes into consideration of the normally consolidated state of soft soils and reflects reasonably the influence of principal stress ratio and stress history in the creep process under plane strain condition.