软黏土小应变剪切模量影响因素试验和模型研究

Experimental and modeling studies on the factors influencing the small-strain shear modulus of soft clay soils

随着城市建设的不断发展,越来越多实际工程建立在软黏土地基上,由于软黏土较差的工程特性在振动荷载作用下会引发大量工程问题。结合实际工程状况,通过共振柱仪器研究了围压、剪应变、含水率、应力路径、固结时间对温州软黏土的动力特性影响。结果表明共振柱试验范围内,软黏土的动剪切模量随围压增大而增大,随剪应变增大而减小,随含水率增大而减小。阻尼比随围压增大而减小,随剪应变增大而增大,与含水率关系不大。进一步分析了固结时间对卸载路径下土的动力特性影响,并用Hardin公式进行了对数据点进行了拟合,试验结果表明动剪切模量随着固结时间的增加而逐渐增加。建立了在加载路径下考虑不同围压、含水率的小应变剪切模量的计算模型。

With the continuous development of urban construction,more and more practical projects are established on soft clay foundations,which can cause a large number of engineering problems under vibratory loading due to the poor engineering properties of soft clay.In this paper,the effects of surrounding pressure,shear strain,moisture content,stress path and consolidation time on the dynamic properties of soft clay soils in Wenzhou are investigated by resonant column apparatus in combination with actual engineering conditions.The results show that the dynamic shear modulus of soft clay increases with the increase of surrounding pressure,decreases with the increase of shear strain,and decreases with the increase of water content in the test range of resonant column.The damping ratio decreases with increasing surrounding pressure,increases with increasing shear strain,and has little relationship with water content.The effect of consolidation time on the dynamic properties of the soil under the unloading path was further analyzed and fitted to the data points using Hardin's formula.A model for calculating the small-strain shear modulus under the loading path considering different surrounding pressure and water content was developed.