预压作用下重塑软土蠕变特性试验研究

Experimental study on creep behavior of reconstituted soft clay considering preloading effect

杭州地区滨海软黏土具有含水量高、强度低和压缩性高等特点,研究其固结蠕变特性对保证构筑物地基稳定具有重要意义。利用GDSAOS全自动固结仪对杭州重塑软黏土展开了一维固结蠕变试验,分析前期预压对土体蠕变特性的影响。试验结果表明:不同加荷比或不同预压条件下,土体蠕变变形量均随加载而逐渐减小;应变与孔隙比时程曲线具有类似发展规律,在应力施加100 min后主固结基本完成,进入次固结阶段;次固结系数与固结压力、预压条件和加荷比均有关,加荷比越小,次固结系数在后期加载中的增长越明显;在相同加载模式下,预压荷载越大,次固结系数在分级加载前期的值越小。这表明可通过施加预压荷载增大土体的固结度,以提高实际工程中软土地基的稳定性。

As a very soft and problematic engineering material,marine soft clay is characterized by high water content,low bearing capacity,and high compressibility,and widely distributed off the coast of Hangzhou city.It is of great importance to investigate the consolidation creep behavior for the group stability analysis.A series of one-dimensional consolidation tests were carried out on Hangzhou reconstituted soft clay specimens using the GDSAOS automatic oedometer to investigate the preloading effect on the creep behavior.The results indicate that the creep deformation of the soil increases with a decelerating rate during the multi-stage loading under different preloading conditions.The vertical strain and void ratio evolve in a similar trend during the primary consolidation.Preloading can be applied to increase the degree of soil consolidation,thereby improving the stability of structures in actual projects.The study found that the secondary consolidation coefficient depends on both the loading increment ratio and preloading conditions.The smaller the loading increment ratio,the more obvious the growth of the secondary consolidation coefficient in the later loading;the larger the preloading magnitude,the smaller the value of the secondary consolidation coefficient in the early stage of multi-stage loading.The research results have reference significance for the safety of structures in the same type of soft clay area.