相对厚度变化下双层软黏土地基固结特性研究

Research on Consolidation Property of Double Layer Soft Clay Foundation under Different Relative Thickness Conditions

采用改装的固结仪,针对吹填场区特有的双层软黏土地基,开展了固结特性试验研究,探讨了土层相对厚度变化对地基变形特性的影响规律。试验结果表明:单层软黏土的变形随试样厚度的增加而增大,双层软黏土的变形与试样厚度比呈明显的正相关关系;上层土厚度为2 cm的双层试样与高度为2 cm的单层试样,前者的稳定沉降大于后者,荷载等级较大时,双层试样的沉降曲线分离程度明显大于单层试样;随着厚度比的增大,厚度比变化对双层地基土体变形的影响逐渐减小;压缩指数随单层软黏土厚度的增大而增大,增大幅度不明显;相对于下层试样,上层试样对双层试样的沉降变形影响更大;随着上层压缩性大的土层厚度的增加,双层地基变形增大、固结速率减小。受土体结构性随固结应力变化的影响,不同厚度及厚度比试样,其沉降曲线随固结压力的增大呈"S"型变化。

Using the modified oedometer,a series of consolidation tests on samples of different size are performed on unique double layer soft clay foundation of reclamation land,which is proposed to study the influence of changes in the relative thickness of soil on the consolidation property. The results show that the final stable deformation increases along with the increasing of thickness of the homogeneous sample and thickness ratio of bilayer specimen. The final stable deformation of bilayer specimen with 2 cm thick upper soil is bigger than that of single sample with 2 cm height,and the strain-time curve degree of separation of bilayer sample significantly is greater than monolayer sample with larger load. Double foundation thickness ratio increasing to a certain extent,the impact on soil deformation will gradually decrease. Compression index decreases slightly along with increasing thickness of soft clay.Compared with the lower sample,the upper sample has a greater impact on settlement deformation. With the increasing thickness of upper compression soil,the deformation increases and consolidation rate decreases. Because of soil structure changing with consolidation stress,the strain curve of sample with different thickness and thickness ratio is ＂ S＂ type with the increasing consolidation pressure.