Effect of freeze-thaw cycles on shear strength of unsaturated bentonite modified clay

2020 ◽  
pp. 102955
Author(s):  
Xin Jing ◽  
Zizhi Cui ◽  
ShuIng Doh ◽  
Li Ma ◽  
Lu Wei ◽  
...  
Keyword(s):  
Shear Strength ◽  
Freeze Thaw ◽  
Modified Clay

Effect of various treatments on consolidation of oil sands fluid fine tailings

2018 ◽  
Vol 55 (8) ◽  
pp. 1059-1066 ◽  
Author(s):  
G. Ward Wilson ◽  
Louis K. Kabwe ◽  
Nicholas A. Beier ◽  
J. Don Scott
Keyword(s):  
Shear Strength ◽  
Oil Sands ◽  
Large Strain ◽  
Regulatory Requirements ◽  
Freeze Thaw ◽  
Treatment Processes ◽  
Fine Tailings ◽  
Fluid Fine Tailings ◽  
Solids Content ◽  
And Storage

Regulatory policy and regulations in Alberta require oil sands companies to reduce their production and storage of fluid fine tailings by creating deposits that can be reclaimed in a timely manner. To meet the regulatory requirements, some companies are adding flocculants to the fluid fine tailings and then using thickeners, inline flocculation or centrifuges to increase the solids content. Freeze–thaw and drying processes are then used to further dewater the tailings. The effects of flocculating, thickening, and freeze–thaw treatments were investigated by performing large-strain consolidation and shear strength tests on these treated fluid fine tailings. The consolidation and shear strength results were then compared with those of untreated fluid fine tailings. All of the treatments increased the hydraulic conductivity of the fluid fine tailings to some degree, but had little to no effect on the compressibility and shear strength. The effects of the treatment processes are discussed and evaluated.

scholarly journals Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1251
Author(s):  
Tao Luo ◽  
Chi Zhang ◽  
Xiangtian Xu ◽  
Yanjun Shen ◽  
Hailiang Jia ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Concrete Structures ◽  
Freezing Temperature ◽  
Frost Damage ◽  
Freezing And Thawing ◽  
Shear Properties ◽  
Freeze Thaw ◽  
Steel Bar ◽  
Concrete Interface

Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze–thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze–thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze–thaw cycles.

THE EFFECTS OF SLOPE POSITION AND CROPPING SEQUENCE ON SOIL PHYSICAL PROPERTIES IN PRINCE EDWARD ISLAND

1988 ◽  
Vol 68 (4) ◽  
pp. 763-774 ◽  
Author(s):  
LINNELL M. EDWARDS
Keyword(s):  
Shear Strength ◽  
Hydraulic Conductivity ◽  
Prince Edward Island ◽  
Soil Depth ◽  
Aggregate Stability ◽  
Penetration Resistance ◽  
Slope Position ◽  
Bottom Slope ◽  
Freezing And Thawing ◽  
Freeze Thaw

Soil physical characteristics were examined at depth intervals of 0–15 and 15–30 cm over three slope positions (top-, mid-, and bottom-slope) for three cropping sequences (hay-barley, cereals-barley, and potato-barley). Hydraulic conductivity was a significant (P ≤ 0.05) 40–50% greater at top-slope than mid- or bottom-slope, and aggregate stability percentage was a significant 6–7% greater at bottom-slope than mid- or top-slope when the soil aggregates were pretreated by freezing and thawing (freeze/thaw). Under the potato-barley sequence shear strength, penetration resistance and bulk density were significantly greater than any other sequence by up to 29, 21 and 15%, respectively; while hydraulic conductivity and maximum penetration depth were, respectively, up to 65 and 28% lower than any other sequences. Under hay-barley, hydraulic conductivity and aggregate stability (freeze/thaw) were, respectively, up to a significant 82 and 10% greater than any other sequence. There was, therefore, significantly more compaction under potato-barley and more soil physical enhancement under hay-barley than other respective sequences. Disease severity was up to 55% greater at bottom-slope than at mid-slope or top-slope for Birka barley, which also showed a significant linear decrease (r2 = 0.89) in yield with increasing shear strength. Yield of Perth barley showed a significant linear increase with increasing soil depth (r2 = 0.92) and clay-silt content (r2 = 0.78). Key words: Aggregate stability (freeze/thaw), crop rotation, penetration resistance, shear strength, barley, potatoes, hay

scholarly journals Physical and Mechanical Characteristics of Shallow Expansive Soil due to Freeze-Thaw Effect with Water Supplement

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yanlong Li ◽  
Zili Wang ◽  
Yang Luo
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Expansive Soil ◽  
Freezing Temperature ◽  
Strength Reduction ◽  
Dry Density ◽  
Direct Shear ◽  
Soil Columns ◽  
Freeze Thaw ◽  
Shear Strength Reduction

Shear strength of shallow expansive soil varies along with the depth under the freeze-thaw effect. This work investigates shear strength characteristics of shallow expansive soil by simulating the actual freeze boundary conditions of seasonal frozen areas with water supplement. An integrated approach incorporating the freeze-thaw test and direct shear test was adopted. Firstly, unidirectional freezing tests for expansive soil columns under three different freezing temperature gradients were carried out. Secondly, direct shear tests under low vertical stress were performed on the standard samples, which were prepared by using cutting rings cut the thawed expansive soil columns into nine segments along with the depth. Temperature, water content, and dry density at different depths were also investigated after the freeze-thaw process. The test results showed that, after the freeze-thaw process, the shear strength of expansive soil columns showed significant differences along with the depth and highly correlated with water content, specifically the higher water content and the lower shear strength. The minimum shear strength in the expansive soil columns occurred at the soil layer below the frozen and unfrozen zones interface. The expansive soil column’s shear strength changed most under the moderate freezing temperature gradient corresponding to the most considerable shear strength reduction. Moreover, the significant decrease in cohesion was the main reason for the shear strength reduction of expansive soil after the freeze-thaw process. These results indicate significant depth variability in shear strength of expansive soil under the freeze-thaw effect.

scholarly journals Relationship between the Shear Strength and Microscopic Pore Parameters of Saline Soil with Different Freeze-Thaw Cycles and Salinities

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1709
Author(s):  
Jiaqi Wang ◽  
Qing Wang ◽  
Sen Lin ◽  
Yan Han ◽  
Shukai Cheng ◽  
...  
Keyword(s):  
Shear Strength ◽  
Pore Structure ◽  
Pore Diameter ◽  
Saline Soil ◽  
Soil Samples ◽  
Average Pore Diameter ◽  
Failure Strength ◽  
Average Pore ◽  
Freeze Thaw ◽  
The Relationship

Saline soil is a widely distributed special soil with poor engineering properties. In seasonally frozen regions, the poor properties of saline soil will cause many types of engineering damage such as road boiling, melt sinking, and subgrade instability. These engineering failures are closely related to the shear strength of saline soil. However, there are relatively few studies on saline soil in cold regions. The strength of the soil is always determined by its microstructure; therefore, the study aims to investigate the relationship between the shear strength and microscopic pore structure of saline soil with different freeze–thaw cycles and salinities. The shear strength characteristics of saline soil with different salinities subjected to different freeze–thaw cycles were obtained by triaxial tests. In addition, the microstructure of the soil samples was investigated by scanning electron microscopy (SEM) tests, and the microscopic pore parameters of the soil samples, including porosity (N), average pore diameter (D¯), average shape coefficient (K), surface fluctuation fractal dimension (F), and orienting probability entropy (Hm), were obtained by image processing software quantitatively. Based on the experimental results, the influence of freeze–thaw cycles and salinity on the shear strength characteristics and microstructure of the soil samples were analyzed. Besides that, in order to effectively eliminate the collinearity between independent variables and obtain a stable and reasonable regression model, principal component regression (PCR) analysis was adopted to establish the relationship between the microscopic pore parameters and the failure strength of the soil samples. The fitting results demonstrated that the failure strength of saline soil is mainly related to the size and direction of the pores in the soil, and it has little correlation with pore shape. The failure strength of the soil was negatively correlated with the average pore diameter (D¯) and porosity (N), and it was positively correlated with the orienting probability entropy of the pores (Hm). This study may provide a quantitative basis for explaining the variation mechanism of the mechanical properties of saline soil from a microscopic perspective and provide references for the symmetry between the changes of the macroscopic properties and microscopic pore structure of the saline soil in cold regions.

Experimental Research on the Characteristics of Soil Strength Freeze-Thaw Weakening in Songhua River Songpu Bank

2014 ◽  
Vol 501-504 ◽  
pp. 403-409
Author(s):  
Xue Han ◽  
Zi Long Zhao ◽  
Zi Rui Gao
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Friction Angle ◽  
Soil Strength ◽  
Internal Friction Angle ◽  
Physical Parameters ◽  
Freezing And Thawing ◽  
Songhua River ◽  
Freeze Thaw ◽  
Soil Shear Strength

In order to study characteristics of soil strength freeze-thaw weakening in the Songhua River Songpu bank，basic physical parameters tests and triaxial compression tests were performed on that paragraph bank .The results showed that: after thawing the sample cohesion will drop substantially, the internal friction angle will increase greatly and soil shear strength will increase significantly; the cohesion of sample after repeated freezing and thawing will significantly decline，internal friction angle of soil will greatly increase，the soil shear strength will increase after the first freezing and thawing，with the increase in the number of freeze-thaw cycles, the soil shear strength will significantly decline. The results can provide Songhua slope stability analysis with a scientific basis.

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