平面变形超固结软黏土蠕变模型研究

Creep model of over-consolidated soft clay under plane strain

通过对原状软土进行平面蠕变实验,研究平面变形条件下超固结软黏土的蠕变特征。研究结果表明,研制的量测装置能独立量测平面应变超固结软土的侧向变形,可规避实验过程体积变形测量精度对侧向变形数据的影响;软土的侧向变形与超固结剪应力比OCR_q具有良好的对应关系,OCR_q能同时反映剪应力和应力历史对软土侧向变形的影响。平面应变状态下体积蠕变系数和轴向蠕变系数均与OCR_q有一一对应关系,依据不同主应力比下的超固结软土平面变形蠕变实验,建立以主应力比和超固结剪应力比为变量的四参数经验模型。所建经验模型包含软土的正常固结状态,可合理反映了主应力比和应力历史对平面变形软土蠕变过程的影响。

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.