Studies on the mechanism of soil consolidation from a view point of micro and macro soil sturctures

从微观和宏观土结构角度研究土体固结机理

基本信息

批准号：
06660291
负责人：
KOGA Kiyoshi
金额：
$ 1.28万
依托单位：
Iwate University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06660291/
关键词：
consolidation secondary consolidation mercury intrusion porosimetry permeability

项目摘要

Change in pore size distribution during consolidation processes was investigated using mercury intrusion porosimeter. Two cohesive soils were consolidated under the stress of 39-1,254 kPa in which load iincrement ratio was 1. Consolidation of specimen was interrupted at the end of the primary consolidation, in the midst of the secondary consolidation and 24 hours after the loading. Each specimen was frozen in liquid nitrogen and dried under a vacuum and subjected to MIP test. It was found in volcanic ash soil that the soil volume change during the primary consolidation is mainly due to the compression of the entrapped pores which includes inter-aggregate pores. On the other hand, soil volume change during the secondary consolidation was caused by the compression of free pores which exist in aggregates.Permeability change during secondary consolidation and stress relaxation processes was investigated using a newly developed consolidation-permeation meter in which the stress and strain of specimen can be automatically controlled by computer and applied water head difference can be precisely kept constant. Kaolin and Iwate volcanic ash soil were subjected to the test. It was revealed that reduction rate of permeability with respect t change in void ratio during the secondary consolidation was higher than the rate during the primary consolidation. The reason for such experimental results was considered as follows. There exists aggregate strucuture in these soils and permeating water mainly flows through inter-aggreagate pores. The inter-aggregate pores including wide portions of the pores are compressed in the primary consolidation process which results in relatively lower reduction rate, whereas the narrow portions of the pores are distorted and narrowed in the secondary consolidation process because of compression and deformation of the aggregates which leads to higher reduction rate. Change in permeability was not observed during the stress relaxation process.

使用汞入侵毛粒仪研究了巩固过程中孔径分布的变化。在39-1,254 kPa的应力下巩固了两个凝聚力的土壤，其中负载IINCREMENT比为1。在初级合并结束时，在次级合并结合结束时中断了样品的固结，并在载荷后24小时中断。将每个样品冷冻在液氮中，并在真空下干燥并进行MIP测试。在火山灰的土壤中发现，主要巩固过程中的土壤体积变化主要是由于包含的孔的压缩，包括聚集孔内孔。另一方面，次级巩固过程中的土壤体积变化是由骨料中存在的自由毛孔的压缩引起的。使用新开发的巩固渗透仪，在次级巩固和应力放松过程中进行了渗透性变化，在这些巩固仪中，可以自动控制标本的应力和应力，而计算机可以自动控制和施加水头差异。高岭土和iwate火山灰土壤进行了测试。据表明，在次级巩固期间，与t变化相关的渗透率的降低速率高于初级整合过程中的速率。这种实验结果的原因如下。在这些土壤中存在聚集的融合物，并渗透到水间毛孔中主要流动。聚集的孔内聚集的孔在主要的固结过程中被压缩，从而导致较低的降低速率，而孔的狭窄部分由于压缩和聚集体的变形而在二次合并过程中狭窄缩小，从而导致较高的降低速率。在应力松弛过程中未观察到渗透率的变化。