Effect of suction on unconfined compressive strength in partly saturated soils

Abstract

Unconfined compression tests are performed in this study to evaluate the effect of matric suction on the strength and the deformation characteristics of dynamically and statically compacted silt soils. In order to estimate the suction stress, the change in suction and the volume change of the soil samples are measured, and the relationship between suction stress and unconfined strength is established. Under different conditions of the initial degree of saturation and the dry density in soils, the relationship between suction and the degree of saturation at failure can be expressed by a unique soil-water characteristic curve. This result shows a similar tendency to that of a predicted equation using the same parameters for the soil-water characteristic curves. The unconfined compressive strength is also affected by the suction stress which seems to work as a confining pressure for unsaturated conditions. These results demonstrate that the suction stress can be used for estimating the relationship between suction and the unconfined compression test.

Experimental and Mathematical Investigations on Unconfined Compressive Behaviour of Costal Soft Soil under Complicated Freezing Processes

“…It is shown from Fig.1 that, no mater what FTC is, the stress-strain curve of CSS consistently appear same shape to two-parameter hyperbolic model 13 , so it can be empirically written as: (2) After using Eq. 2 to fit or describe investigated stressstrain data, many researchers have found the inferior of twoparameter hyperbolic model 14 .…”

“…Te work team of Liu 1 conducted the assessment of unconfined compressive strength of cement stabilized marine clay. Effect of suction on unconfined compressive strength in partly saturated soils was discussed 2 and the unconfined compressive strength of compacted granular soils by using inference systems was discussed 3,4 . In some case, soil foundation or slope may experience freezing-thawing circle (FTC) process due to nature season change, day and night temperature difference, or artificial freezing engineering, which would make big difference to unconfined compressive strength of soil 5,6 .…”

Effect of suction stress on strength characteristics of a compacted silty soil under low confining pressure

“…In the unconfined compression test for unsaturated soil, the minimum principal net stress equals to zero because of no confining pressure, and the Mohr's stress circle attaches to the failure plane on the condition that the suction stress behaves as a confining stress similar to the negative pore water pressure acting in the saturated state (Chae et al, 2010). Figure 2 shows the Mohr's stress circle for the unconfined compression test and the constant water content test in this paper, in which the total of the suction stress, ps and the minimum principal net stress, σ3 act as the equivalent confining stress.…”

Shear modules of claysand mixtures using bender element test

“…It is interpreted that the difference in testing results can be attributed to the soil suction as well as quantity and physical characteristics of the sand grains (shape, size) leading to various void ratios. The soil suction could be effective in the shear strength and the deformation characteristics of soils for the highly saturated condition at the unconfined compression test [37][38][39]. However, it seems to be beyond the scope of this study to provide a detailed discussion on the soil suction, since the amount of water was selected as wopt for each specimen that creates a very similar range of saturation degree as well as soil suction in all the specimens tested ( Table 2).…”