Abstract
When the traditional one-dimensional consolidator is used to study the creep characteristics of loess, due to the hoop effect of the ring cutter, only the attenuation creep stage and stable creep stage of loess can be studied, but the accelerated creep stage cannot be presented. In order to avoid the influence of drilling on the creep characteristics of loess, the paper improves the consolidation instrument by drilling holes along the diameter direction in the center of the sample to provide artificial space for soil failure. At the same time, the sample size is increased to ensure that the diameter of the sample is greater than five times of the diameter of the borehole, so as to avoid the influence of drilling on the creep characteristics of loess. The creep characteristics of loess are studied by step loading (vertical pressure at all levels is 125 kPa, 175 Pa, 225 kPa, and 275 kPa), and the whole creep process characteristic curves of loess under different stress conditions are obtained. An endoscope was placed in the hole to observe the deformation and failure characteristics of loess in different stages of creep. This method makes up for the defect that the traditional one-dimensional consolidator cannot obtain the whole process characteristics of loess creep. At the same time, it has the advantages of simple operation, less external influence factors, stronger data reliability, and can directly observe the changes of loess creep soil. It has a beneficial role in promoting the experimental research of loess creep characteristics.
Highlights
When the traditional one-dimensional consolidator is used to study the creep characteristics of loess, due to the hoop effect of the ring cutter, only the attenuation creep stage and stable creep stage of loess can be studied, but the accelerated creep stage cannot be presented
The sample size is increased to ensure that the diameter of the sample is greater than five times of the diameter of the borehole, so as to avoid the influence of drilling on the creep characteristics of loess. e creep characteristics of loess are studied by step loading, and the whole creep process characteristic curves of loess under different stress conditions are obtained
Bjerrum carried out creep test on Norwegian marine clay and analyzed the micromechanism of cohesive soil during long-term deformation [8]. rough a series of one-dimensional consolidation and isotropic consolidation tests, Mesri and Godlewski pointed out that the soil with high compressibility in the main consolidation stage has relatively high compressibility in the secondary consolidation stage [9]
Summary
(1) In order to separate the sample from the ring cutter after the test, attention should be paid to the lubrication treatment of the wall of the ring cutter. Drilling should be carried out slowly and uniformly to reduce disturbance to the sample. (3) e retaining ring, permeable plate, and thin filter paper are placed in the consolidation container. Install the ring cutter with the sample into the. 1-test platform 2-loading weight 3-transfer lever 4-water tank 5-retaining ring 6-sample 7-ring cutter. 8-sample drilling 9-permeable stone 10-pressure upper cover 11-loading guide rod 12-displacement meter 13-displacement meter frame. In filter paper, permeable plate, and pressurized upper cover are placed on the sample in turn. (7) After the test, the sample is separated from the ring cutter. (7) After the test, the sample is separated from the ring cutter. e samples were sliced at the quarter diameter, half diameter, and diameter. e distribution law of plastic failure of soil around each section of the borehole was recorded
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