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黏滞系数是表征土的蠕变和流动特性的重要指标。对黄石、漳州、青岛地区结构性软土进行电子显微镜扫描、颗粒分析、X衍射试验和化学分析试验,测试结果表明,软土的粒度成分、矿物成分、物理化学性质、结构类型对黏滞系数影响较大。软土蠕变过程中,结构单元体发生定向排列或产生滑动,其相对运动使结合水的黏滞性反映出来,进而引起黏滞系数的变化。进行直接剪切蠕变试验,并通过陈氏法处理蠕变试验数据。试验结果表明,黏滞系数随剪应力的增加达到峰值,固结压力越大,峰值体现越明显,峰值对应的剪应力也越大,这主要是微观结构随剪应力增大逐渐破损所引起的。固结压力增大,结合水膜厚度变薄,土颗粒间连接力增强,黏滞系数也随之增大。用不同固结压力下黏滞系数峰值对应的剪应力代替临界抗剪强度,提出了一个新的求取长期强度的方法,并通过试验数据验证了方法的正确性。该研究有助于进一步认清蠕变机制,对修正或建立较为符合实际的本构模型有一定意义。
The viscosity coefficient is an important indicator of soil creep and flow characteristics. The structural soft soils of Huangshi, Zhangzhou and Qingdao were scanned by electron microscopy, particle analysis, X-ray diffraction and chemical analysis. The results showed that the granularity, mineralogical composition, physico-chemical properties, Greater impact. In the creep process of soft clay, the structural elements are aligned or slip, and the relative movement reflects the viscosity of the bound water, which in turn leads to the change of the viscosity coefficient. Direct shear creep test, and by Chen’s method of creep test data. The experimental results show that the viscosity coefficient reaches the peak value with the increase of shear stress. The larger the consolidation pressure is, the more obvious the peak value is and the larger the peak value is corresponding to the shear stress. This is mainly caused by the gradual damage of microstructure with the increase of shear stress . Consolidation pressure increases, with the thinning of the water film thickness, the bonding force between soil particles increases, the viscosity coefficient also increases. The shear strength corresponding to the peak value of the viscosity coefficient under different consolidation pressures is used instead of the critical shear strength. A new method for obtaining long-term strength is proposed. The correctness of the method is verified by experimental data. This study helps to further understand the mechanism of creep and is of some significance to correct or establish a more realistic constitutive model.