柔性侧限条件下软土的变形特性及固结模型

软黏土具有含水率高、压缩性强、泊松比大的物理特性。对于深厚软黏土地基而言，在竖向荷载的作用下很难保证侧向变形为0，适当考虑侧向变形的柔性约束条件可能更符合工程实际。因此，提出了柔性侧限条件下的竖向固结试验方法，对原状土样及重塑土样分别进行了不同侧向约束条件下的竖向固结对比试验，分析了侧限条件对软黏土沉降特征及变形参数的影响。试验成果表明，柔性侧限条件下土体的主固结变形量、次固结变形量均较K0侧限条件下的大，主固结完成时间较短，且等时曲线非线性化程度更高。基于试验成果及ε-lgp曲线，引入非达西渗流理论，对一维Terzaghi经典固结理论进行修正，建立了柔性侧限约束条件下的非线性控制方程，此计算模型参数通过柔性侧限固结试验获取，可计算一定侧向变形条件下土体的变形特性，通过对室内试验成果的模拟验证了模型的有效性。

Deformation behavior and consolidation model of soft soil under flexible lateral constraint

Soft clay is characterized by high water content, large compressibility and Poisson's ratio. For thick soft soil foundation, it is difficult to ensure that the lateral deformation remains zero under vertical loading. The condition of flexible constraints with proper consideration of lateral deformation is more realistic with engineering practices. Therefore, in this paper, a consolidation test with flexible lateral constraints was conducted on the undisturbed and remodeled soils. The influences of the lateral constraints on the settlement characteristics and deformation parameters of soft clay were investigated. The results show that both the primary and secondary consolidation deformations of the soil under flexible constraints are greater than those under the K0 lateral confining conditions, as well as performing a shorter consolidation time and more nonlinear isochronous curves. The theory of non-Darcy flow was introduced to modify the Terzaghi’s consolidation theory, so that nonlinear governing equations considering the certain lateral deformation effect were deduced. Furthermore, the parameters of the calculated model were obtained from the flexible lateral restraints consolidation tests. Finally, the validity of the proposed model was verified by the laboratory test results.