Model Test Study on Stability Factors of Expansive Soil Slopes with Different Initial Slope Ratios under Freeze-Thaw Conditions

Expansive soil is widely distributed in seasonally frozen areas worldwide. Due to the special expansion and shrinkage characteristics of expansive soil related to water content, there are potential engineering disasters in the subgrade and slope engineering. To investigate the physical and mechanical changes within the expansive soil slope, four freeze-thaw cycles tests were performed on expansive soil slope models in an environmental chamber with slope ratios 1:1.5, 1:1 and 1:0.5. Nuclear magnetic resonance (NMR) technology is used to explain the pore changes in expansive soil during freezing and thawing. Model tests were carried out to monitor the changes in cracks, moisture content, temperature, displacement and soil pressure of the slope model. The results show an increase in the slope ratio may give rise to more intense temperature changes, promote the development of cracks in the model, and increase the temperature gradient and moisture migration rate during freezing and thawing. Following freeze-thaw cycling, the soil structure is destroyed and reassembled, and the soil pressure decreases as the slope ratio increases. Combined with the displacement of slope model and NMR test results, the slope can maintain a stable state after multiple freezing–thawing cycles under a specific moisture content ωs.

Download Full-text

Experimental study of the freeze thaw characteristics of expansive soil slope models with different initial moisture contents

Scientific Reports ◽

10.1038/s41598-021-02662-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Zhongnian Yang ◽

Jianhang Lv ◽

Wei Shi ◽

Chao Jia ◽

Chu Wang ◽

...

Keyword(s):

Moisture Content ◽

Expansive Soil ◽

Soil Slope ◽

Soil Pressure ◽

Freeze Thaw ◽

Moisture Contents ◽

Thaw Cycle ◽

Soil Slopes ◽

Freeze Thaw Cycle ◽

Opposite Behavior

AbstractThis paper presents an experimental investigation on the effect of freeze–thaw cycling on expansive soil slopes with different initial moisture contents. Clay soil from Weifang, China, was remolded and selected to build the expansive soil slope for the indoor slope model tests. A total of five freeze–thaw cycles were applied to the three expansive soil slopes with different moisture contents ranging from 20 to 40%. Variations of the crack developments, displacements, soil pressures and moisture contents of the expansive soil slope with different initial moisture contents during the freeze–thaw cycling were reported and discussed. The results indicate that higher moisture contents can slow the development of cracks and that the soil pressure increases with decreasing temperature. The soil pressure of slope decreases after freeze–thaw cycle, and the change amplitude of soil pressure after freeze–thaw is proportional to water content. The slopes with a moisture content of 20% and 30% shrinks during freezing and expands during thawing, which was named ES-FSTE Model, while the slope with a 40% moisture content shows the opposite behavior. During freeze–thaw cycles, moisture migrates to slope surface. As initial moisture contents increase, the soil heat transfer rate and bearing capacity decreases after five freeze–thaw cycling.

Download Full-text

FREEZE-THAW EFFECTS ON GRANULAR STRUCTURE REORGANIZATION FOR SOIL MATERIALS OF VARYING TEXTURE AND MOISTURE CONTENT

Canadian Journal of Soil Science ◽

10.4141/cjss88-047 ◽

1988 ◽

Vol 68 (3) ◽

pp. 485-494 ◽

Cited By ~ 31

Author(s):

S. PAWLUK

Keyword(s):

Moisture Content ◽

Lacustrine Sediments ◽

Field Capacity ◽

Granular Structure ◽

Glacial Till ◽

Microstructural Development ◽

Clay Loam ◽

Freezing And Thawing ◽

Freeze Thaw ◽

Repeated Freezing

Repeated freezing and thawing of glacial till cores of clay loam texture results in the formation of granic and metafragmic microfabrics. These units of fabric are best developed near the surface of cores kept at moisture levels between field capacity and saturation. Well-sorted lacustrine sediments with fewer voids tend to form banded fabrics. Many of the morphological features such as vesicles, metavughs and desiccation cracks commonly attributed to freeze-thaw processes are evident in all materials tested. Discrete units of fabric observed in this study are very similar to units of fabric observed in the Ah horizons of Black Chernozemic and Cryosolic soils. Results of this investigation strongly support earlier research which suggests that frost processes are major contributors to their microstructural development. Key words: Granic, freeze-thaw, microfabrics

Download Full-text

Effects of cyclic freezing and thawing on volume changes and permeabilities of soft fine-gained soils

Canadian Geotechnical Journal ◽

10.1139/t96-079-301 ◽

1996 ◽

Vol 33 (4) ◽

pp. 529-537 ◽

Cited By ~ 108

Author(s):

K D Eigenbrod

Keyword(s):

Moisture Content ◽

Initial Moisture Content ◽

Maximum Volume ◽

Freezing And Thawing ◽

Volume Changes ◽

One Dimensional ◽

Freeze Thaw ◽

Fine Grained ◽

Liquidity Index ◽

Thaw Consolidation

Soft, fine-grained soils were exposed to cyclic one-dimensional, open-system freezing and thawing, resulting in maximum volume changes of up to 30%, depending on the initial moisture content and plasticity of the clay as well as on the rate of freezing. A linear relationship between the net volume changes subsequent to freezing and thawing and the liquidity index prior to freezing and thawing was obtained. This correlation is not unique, but depends on rate and mode of freezing. Thus, settlements from freezethaw consolidation in the field can be predicted from such tests if the rate and mode of freezing are the same as in the field. During cyclic freezing and thawing the soils became fissured and jointed, resulting for most clays in large increases in their bulk permeabilities, which increased with an increasing number of freezethaw cycles, often by more than two orders of magnitude. For some materials, however, little change in permeability occured. Key words: cyclic freezethaw, clays, freezethaw consolidation, permeability, volume changes.

Download Full-text

Hydrothermal Effects of Freeze-Thaw in the Taklimakan Desert

Sustainability ◽

10.3390/su13031292 ◽

2021 ◽

Vol 13 (3) ◽

pp. 1292

Author(s):

Liu Xinchun ◽

Kang Yongde ◽

Chen Hongna ◽

Lu Hui

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Ambient Temperature ◽

Soil Temperature ◽

Soil Moisture Content ◽

Soil Freezing ◽

Taklimakan Desert ◽

Freezing And Thawing ◽

Freeze Thaw ◽

The Taklimakan Desert

The Taklimakan Desert, also known as the “Sea of Death”, is the largest desert in China and also the world’s second largest remote desert. The road crossing the Taklimakan Desert is the longest desert road in the world and has been the center of the Silk Road since ancient times. Based on field observation data (November 2013 to May 2014) collected from the Tazhong and Xiaotang stations, we studied the interannual and diurnal variations of soil temperature, soil moisture content, and surface heat fluxes during different freezing and thawing periods. The annual and daily changes of soil temperature, soil moisture content, and surface energy fluxes at different freezing and thawing stages were analyzed. We illustrated the coupling relationship between water and heat in freezing-thawing soil in the Taklimakan Desert. We established a coupling model of soil water and heat during freezing and thawing. During the soil freezing period, the soil temperatures at different depths generally trended downward. The temperature difference between the Tazhong station and the Xiaotang station was 4~8.5 °C. The freezing time of soil at 20 cm depth occurred about 11 days after that at 10 cm depth. The effect of ambient temperature on soil temperature gradually weakened with the increase of soil depth. With the occurrence of the soil freezing process, the initial soil moisture contents at 5 cm, 10 cm, 20 cm, and 40 cm depths at the Xiaotang station were 6%, 10%, 29%, and 59%, respectively, and those at the Tazhong station were 5%, 3.6%, 4.4%, and 5.8%, respectively. As the ambient temperature decreased, the freezing front continued to move downward and the liquid soil water content at each depth decreased. The desert highway is closely related to the economic development and prosperity of southern Xinjiang. Therefore, it is important to maintain and inspect the safety and applicability of freeze-thaw zones and avoid casualties from vehicles and personnel.

Download Full-text

Numerical Simulation of the Stability of Added Lime Expansive Soils Embankment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.838-841.821 ◽

2013 ◽

Vol 838-841 ◽

pp. 821-824

Author(s):

Qi Yong You

Keyword(s):

Expansive Soils ◽

Expansive Soil ◽

Soil Slope ◽

Slope Ratio ◽

Embankment Slope ◽

Calculation Results ◽

Expansion Force ◽

The Stability ◽

Depth Of Infiltration ◽

Reasonable Model

The main reason of expansive soil embankment slope landslide is the infiltration of rainwater. Analyzing engineering characteristics and failure mechanism of expansive soil embankment slope, considering the force of expansion under the infiltration of rainwater, and choosing the appropriate constitutive model, simulate expansive soil embankment slope under humidification state. According different conditions of the expansive soil and different depth of infiltration, and simplifying the swelling force, establish a simple and reasonable model of expansion force changes. Expansive soil embankment slope stability is mainly affected by the moisture of expansive soil slope after analyzing the calculation results. The safety of expansive soil slope after immersion in rainwater decreases significantly. It shows designers should choose reasonable slope ratio and consider the embankment slope protection and drainage measures.

Download Full-text

Analysis of shallow landslide mechanism of expansive soil slope under rainfall: a case study

Arabian Journal of Geosciences ◽

10.1007/s12517-021-06829-6 ◽

2021 ◽

Vol 14 (7) ◽

Author(s):

Chao Liang ◽

Zhijian Wu ◽

Xinfu Liu ◽

Zhaomei Xiong ◽

Tao Li

Keyword(s):

Expansive Soil ◽

Shallow Landslide ◽

Soil Slope ◽

Landslide Mechanism

Download Full-text

Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

Advances in Civil Engineering ◽

10.1155/2020/5921901 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Huren Rong ◽

Jingyu Gu ◽

Miren Rong ◽

Hong Liu ◽

Jiayao Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Pore Size ◽

Power Function ◽

Damage Mechanism ◽

Uniaxial Compression Test ◽

Freezing And Thawing ◽

Freeze Thaw ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

Download Full-text

Review of Strength and Failure Criteria for Concrete After Freeze-Thaw Damage

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.253-255.456 ◽

2012 ◽

Vol 253-255 ◽

pp. 456-461

Author(s):

Yan Fu Qin ◽

Bin Tian ◽

Gang Xu ◽

Xiao Chun Lu

Keyword(s):

Normal State ◽

Concrete Strength ◽

Failure Criteria ◽

Concrete Durability ◽

Freezing And Thawing ◽

Normal Concrete ◽

Strength Criteria ◽

Freeze Thaw ◽

Ordinary Concrete ◽

Concrete Failure

Frost resistance research is one of the important subject of concrete durability, however strength criteria is an important part of the study of mechanical behavior of concrete. So far, about concrete failure criteria are almost for normal concrete, which the domestic and overseas scholars have comparative detailed research in every respect to it, and to freeze-thaw damage of concrete but few research. Based on the summary of the existing ordinary concrete strength and failure criteria in normal state and after freeze-thaw damage，this paper have a brief comment of failure criteria on concrete after freeze-thaw damage. For later research about concrete strength and failure criteria under freezing and thawing cycle provide the reference.

Download Full-text