Influence of bimodal structure on the soil freezing characteristic curve in expansive soils

2021 ◽  
pp. 103437
Author(s):  
Lingming Kong ◽  
Aolin Yu ◽  
Ke Liang ◽  
Jilin Qi
Keyword(s):  
Expansive Soils ◽  
Characteristic Curve ◽  
Soil Freezing ◽  
Bimodal Structure

Prediction of resilient modulus of frozen unbound road materials using soil-freezing characteristic curve

2018 ◽  
Vol 55 (8) ◽  
pp. 1200-1207 ◽  
Author(s):  
Junping Ren ◽  
Sai K. Vanapalli
Keyword(s):  
Resilient Modulus ◽  
Characteristic Curve ◽  
Soil Freezing ◽  
Subzero Temperature ◽  
Proposed Model ◽  
Road Materials ◽  
Frozen State ◽  
Drying Conditions ◽  
Semi Empirical

The resilient modulus is a key parameter required in the mechanistic design of pavements. Experimental determination of the resilient modulus requires elaborate equipment for testing and requires trained personnel; for this reason, it is expensive. There are several models for predicting the resilient modulus for unbound road materials that take into account the influence of wetting and drying conditions. However, well-established models are not available for the prediction of the resilient modulus of these materials in a frozen state. In this paper, a semi-empirical model, which uses a soil-freezing characteristic curve as a tool, is proposed for predicting the variation of the resilient modulus with subzero temperature and the associated cryogenic suction for frozen soils. Experimental data on seven different pavement unbound materials were used to validate the proposed model. It is shown that the model can reasonably predict the resilient modulus of the investigated soils that are in a frozen state. More investigations on different types of soils would be useful to better understand the strengths and limitations of the proposed model.

Estimating soil-water characteristic curve from soil-freezing characteristic curve for mine waste tailings using time domain reflectometry

2020 ◽  
Vol 57 (1) ◽  
pp. 73-84 ◽  
Author(s):  
Haley Schafer ◽  
Nicholas Beier
Keyword(s):  
Experimental Method ◽  
Soil Water ◽  
Time Domain ◽  
Oil Sands ◽  
Mine Waste ◽  
Characteristic Curve ◽  
Time Domain Reflectometry ◽  
Soil Freezing ◽  
Copper Tailings ◽  
Gold Tailings

The unsaturated properties of a soil are required to predict the rate of dewatering and magnitude of strength gain of a mine waste tailings deposit during desiccation dewatering. This prediction requires the soil-water characteristic curve (SWCC), which is time-consuming and challenging to attain and may take anywhere from weeks to months to complete a single test. As a result, alternative methods are needed to estimate the SWCC. Past research has indicated that the soil-freezing characteristic curve (SFCC) can be used to estimate the SWCC in some soils. An experimental method and apparatus were developed to measure the SFCC to estimate the SWCC for different mine waste tailings, including copper tailings, gold tailings, and oil sands centrifuge cake. The experimental method involved using a resistance temperature detector to measure the temperature and time domain reflectometry to determine the unfrozen water content of the soil. The results showed that the SFCC could be used to estimate the SWCC for tailings from metal mines (gold tailings and copper tailings) with a high portion of sand-sized particles and a small amount of clay-sized particles, but was not able to estimate the SWCC for oil sands tailings.

scholarly journals Swelling Curve in Terms of Effective Stress for Expansive Clays

2020 ◽  
Vol 195 ◽  
pp. 02023
Author(s):  
Rafael Baltodano-Goulding
Keyword(s):  
Effective Stress ◽  
Expansive Soils ◽  
Characteristic Curve ◽  
The State ◽  
Isomorphous Substitution ◽  
High Plasticity ◽  
Charge Imbalance ◽  
Swell Potential ◽  
Free Swell ◽  
A Charge

Expansive soils can present an unsaturated state where the soil exhibits volume changes due to both moisture variations that change the state of stresses and moisture variations that interact with its mineralogical characteristics. These special kinds of soils are normally clay type soils that had suffered isomorphous substitution creating a charge imbalance of the clay mineral crystals. This imbalance promotes the trapping of water molecules by the clay particles. It is commonly assumed that a high plasticity index can be an indication of a clay´s high swell potential. However, in arid regions, it is possible to have clays with very high swell potential and low plasticity indexes due primarily to a decrease in the state of effective stress, which will produce expansion of the material. It is common practice to study the swelling characteristics of these soils by performing free-swell tests that can be used for designing removal and replacement backfills or drilled shafts. However, the expansion percentage obtained from this type of test is actually in terms of total stresses and not in terms of effective stress, as it is commonly assumed. Moreover, it is highly dependent on the magnitude of the preload used. This paper presents some efforts made to obtain the swelling part of the curve in terms of effective stresses from the traditional free-swell test. It was hypothesized that the shape of this curve could either have the shape of the rebound curve from a saturated consolidation test or a shape similar to the soil-water characteristic curve.

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