Thaw Settlement and Mechanical Properties of Admixture-Stabilized Frozen Soil

2020 ◽  
Vol 34 (2) ◽  
pp. 04020005
Author(s):  
Zhaohui (Joey) Yang ◽  
Feng Zhang ◽  
Xinlei Na ◽  
Haolin Yu
Keyword(s):  
Mechanical Properties ◽  
Frozen Soil ◽  
Thaw Settlement

scholarly journals Mechanical behavior of frozen soil improved with sulphoaluminate cement and its microscopic mechanism

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhenhua Yin ◽  
Hu Zhang ◽  
Jianming Zhang ◽  
Mingtang Chai
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Soil Improvement ◽  
Particle Size Analysis ◽  
Frozen Soil ◽  
Size Analysis ◽  
Permafrost Soil ◽  
Compression Tests ◽  
Microscopic Mechanism ◽  
Sulphoaluminate Cement

Abstract The foundation of constructions built in the permafrost areas undergo considerable creeping or thawing deformation because of the underlying ice-rich permafrost. Soil improvement may be of advantage in treating ice-rich permafrost at shallow depth. Sulphoaluminate cement was a potential material to improve frozen soil. Simultaneously, two other cements, ordinary Portland cement and Magnesium phosphate cement were selected as the comparison. The mechanical behavior of modified frozen soil was studied with thaw compression tests and unconfined compression strength tests. Meanwhile, the microscopic mechanism was explored by field emission scanning electron microscopy, particle size analysis and X-ray diffractometry. The results showed Sulphoaluminate cement was useful in reducing the thaw compression deformation and in enhancing the strength of the frozen soil. The improvement of the mechanical behavior depended mainly on two aspects: the formation of structural mineral crystals and the agglomeration of soil particles. The two main factors contributed to the improvement of mechanical properties simultaneously. The thicker AFt crystals result in a higher strength and AFt plays an important role in improving the mechanical properties of frozen soils.The study verified that Sulphoaluminate cement was an excellent stabilizer to improve ice-rich frozen soils.

Stress Analysis of Buried Pipelines Under Thaw Settlement of Permafrost Zone Based on Moisture-Heat-Stress Coupled Analysis

2020 ◽  
Author(s):  
Jinxu Jiang ◽  
Hong Zhang ◽  
Jianping Liu ◽  
Pengchao Chen ◽  
Xiaoben Liu
Keyword(s):  
Thermal Conductivity ◽  
Vertical Displacement ◽  
Frozen Soil ◽  
Ground Temperature ◽  
Permafrost Zone ◽  
Insulation Material ◽  
Longitudinal Stress ◽  
Buried Pipelines ◽  
Safe Operation ◽  
Thaw Settlement

Abstract Permafrost thawing caused by the hot crude pipeline is a major threat to the safe operation of buried pipelines in permafrost zone. In this paper, the process of thawing and consolidation of frozen soil is considered, and a three-dimensional (3D) finite element model of buried pipelines in permafrost zone is established using ABAQUS. The calculation of thaw settlement displacement of frozen soil based on moisture-heat-stress coupled was carried out, and the deformation and stress of buried pipelines were analyzed. The effects of ground temperature, oil temperature, thermal conductivity of insulation material and soil distribution along the pipeline on the vertical displacement and longitudinal stress of buried pipelines in frozen soil were studied. Research results show that in thaw-unstable soil, the vertical displacement and stress of the pipeline increase significantly with the increase of the average ground temperature, and change on ground temperature amplitude has a little effect on the vertical displacement and longitudinal stress of the pipeline in thaw settlement zone. It is 1/3 of the vertical displacement of the pipeline without a heat insulating layer. When the thermal conductivity of the insulation material is less than 0.4 W/m °C, the vertical displacement of the pipeline in the thawing zone can be further reduced by reducing the thermal conductivity of the insulation material. When clay and sand appear alternately along the pipeline, the vertical displacement and longitudinal stress of the pipeline can be reduced by reducing the length of clay section. This study has certain reference value for optimizing the design parameters of buried pipelines in permafrost zone and reducing the impact of differential thaw settlement of frozen soils on the safe operation of pipelines.

The Study on Mechanical Properties of the Graded Broken Stone Mixed with Cement and Fine Powder

2014 ◽  
Vol 905 ◽  
pp. 230-234
Author(s):  
Jun Lei Tian ◽  
Yan Ke Yang ◽  
Yi Ping Hu ◽  
Jian Qiang Cheng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Regression Analysis ◽  
Flexural Strength ◽  
High Speed ◽  
Fine Powder ◽  
Frozen Soil ◽  
Power Exponent ◽  
High Speed Railway ◽  
Railway Passenger

Ha Tai railway passenger dedicated line is a national key project of the eleventh five-year plan. Its different from other construction of high-speed railway because there is many frozen soil over the place. The requirement of the subgrade material is higher.We proposed a idea that gradred broken stone mixed with cement and fine powder applied in the project.The compressive strength,splitting tensile strength and flexural strength were studied and analyzed through laboratory test.And regression analysis between compressive strength and flexural strength was made .According to the regression analysis,a power exponent function between flexural strength and compressive strength was got.Based on this,the corresponding relationship table was deduced,which can be used in practical projects.

Influence of Moisture Content to the Freeze-Thaw Performance of Roadbed in High-Cold Areas

2013 ◽  
Vol 442 ◽  
pp. 342-345 ◽  
Author(s):  
Qiao Ling Wu ◽  
Yong Sheng ◽  
Feng Xie
Keyword(s):  
Moisture Content ◽  
Optimum Moisture Content ◽  
Frozen Soil ◽  
Frost Heave ◽  
Document Code ◽  
Freeze Thaw ◽  
Subgrade Soil ◽  
The Common ◽  
Thaw Settlement ◽  
The Stability

Frost-heave and thaw-settlement of roadbed soil in highway will influence directly the durability, safe traffic flow and construction & maintenance costs in high-cold areas, therefore, recognizing and analysing the common embankment technologies of highway roadbed in high-cold areas accurately is significant to the effective controlling of project invest and the highway construction with limited funds in minority areas. The relations of Moisture Content and the freeze-thaw performances of roadbed fillers, subgrade soil were got respectively by experiments, and the results shows: Moisture Content has larger influence on the frost-heave and thaw-settlement performance of the soil. During the embankment of roadbed, the Moisture Content of fillers should be controlled nearby the optimum Moisture Content. The frost-heave and thaw-settlement occurs mainly in the subgrade soil, controlling the Moisture Content of subgrade soil is very important to improve the up-limit of frozen-soil, keep the stability of frozen-soil, control the thaw-settlement of roadbed and get rid of the roadbed diseases. CLC: U416.1 Document code: B

scholarly journals Improvement of Compressibility and Thaw-Settlement Properties of Warm and Ice-Rich Frozen Soil with Cement and Additives

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1068 ◽  
Author(s):  
Mingtang Chai ◽  
Jianming Zhang
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Water Content ◽  
Constant Load ◽  
Frozen Soil ◽  
Unfrozen Water ◽  
Improvement Effect ◽  
Thaw Settlement ◽  
Scanning Electron ◽  
Permafrost Regions

The warm and ice-rich frozen soil (WIRFS) that underlies roadway embankments in permafrost regions exhibit large compression and thaw deformation, which can trigger a series of distresses. Cement and additives were used in this study to improve the compressibility and thaw-settlement properties of WIRFS. We, therefore, selected optimum additives and studied the improvement effect on the frozen soil with 30% water content based on our previous research. Given constant load and variable temperatures, compression coefficients, thaw strains, and water content changes were obtained at temperatures of −1.0 °C, −0.5 °C, and 2.0 °C to evaluate the effect of improvements. A scanning electron microscope (SEM) was then used to observe the microstructure of improved soils and analyze causal mechanisms. Data show that hydration reactions, physical absorptions, cement, and additives formed new structures and changed the phase of water in frozen soil after curing at −1.0 °C for 28 days. This new structure, cemented with soil particles, unfrozen water, and ice, filled in the voids of frozen soil and effectively decreased the WIRFS compression coefficient and thaw strain.

Properties of Frozen Soils for Cross Passage Construction in Line 1 and 2 of Wuxi Metro

2013 ◽  
Vol 353-356 ◽  
pp. 1662-1665 ◽  
Author(s):  
Xiang Dong Hu ◽  
Yan Guang Han
Keyword(s):  
Mechanical Properties ◽  
Laboratory Tests ◽  
Freezing Point ◽  
Frozen Soil ◽  
Frost Heave ◽  
Soil Test ◽  
Frozen Soils ◽  
Freezing Method ◽  
Ground Freezing ◽  
Artificial Ground Freezing

Artificial ground freezing method (AGF) was applied in cross passage constructing of line 1 and 2 of Wuxi Metro. Mechanical properties of frozen soils such as uniaxial compressive strength, modulus of elasticity, Poissons Ratio, frost heave rate and freezing point are prerequisite for design and construction of AGF. In order to obtain the parameters mentioned, laboratory tests were conducted. One was the basic geotechnical test. Another was the frozen soil test.

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