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Hydraulic conductivity of frozen soil is indispensable for describing water flow process in freezing soils. However, this conductivity is difficult to measure in the laboratory. So, the objective of this study is to propose a simple and smooth hydraulic conductivity model for saturated frozen soil based on the soil freezing characteristic curve (SFCC). Considering that the volume of pore water approximately represents the pore volume, the distribution of effective pore radii changed as a function of temperature was determined by combining the SFCC and the Gibbs–Thomson equation. Based on the distribution of effective pore radii, Hagen-Poiseuille equation, Darcy’s law, relative hydraulic conductivity and tortuosity, a simple and smooth hydraulic conductivity model for saturated frozen soil based on the SFCC was proposed. To illustrate the model performance, eight existing experimental cases were analyzed. The results showed that predictions considering the three different tortuosity formulations were in good agreement with the tested data; the results were worse when not considering the tortuosity and the results were best when considering the tortuosity τF=B/rb2. Moreover, the predictive modeling power was related to the tortuosity function. Furthermore, the model was further compared with the previous models, the results of which showed the better performance of the proposed model. The model is quite simple and timesaving to use when the SFCC and the saturated hydraulic conductivity are available. This result provides a new idea for developing the hydraulic conductivity model of saturated frozen soil.
Xiyan Zhang; Dongqing Li; Lei Chen; Feng Ming; Yuhang Liu. A new integral model for predicting the hydraulic conductivity of saturated frozen soil. Journal of Hydrology 2021, 603, 126838 .
AMA StyleXiyan Zhang, Dongqing Li, Lei Chen, Feng Ming, Yuhang Liu. A new integral model for predicting the hydraulic conductivity of saturated frozen soil. Journal of Hydrology. 2021; 603 ():126838.
Chicago/Turabian StyleXiyan Zhang; Dongqing Li; Lei Chen; Feng Ming; Yuhang Liu. 2021. "A new integral model for predicting the hydraulic conductivity of saturated frozen soil." Journal of Hydrology 603, no. : 126838.
The artificial ground freezing (AGF) method has been widely used in underground engineering construction. As the main load-bearing elements of the AGF method, the strength of frozen walls is expected to play a crucial role in engineering stability. To improve the accuracy of quantitative evaluations of engineering stability, it is necessary to grasp the strength characteristics of frozen rock during service. To achieve this, the red sandstone taken from a frozen shaft project was tested via triaxial compression at different temperatures (−5°C,−10°C,−15°C,−20°C,−25°C, and −30°C). After that, a damage constitutive model with a Weibull distribution was derived to characterize the damage development of the frozen sandstone. Based on the validated model, the variation of damage degree was analyzed. The results show that the crack initiation stress, crack dilation stress, and peak strength all increase with decreasing temperature. The crack damage threshold increases as the frozen sandstone strength increases. The presented damage constitutive model can reflect the damage evolution of frozen sandstone. When the stress exceeds the crack initiation stress, the damage degree begins to increase, and it increases quickly when the stress approaches the peak strength. The model parameters can reflect the influence of negative temperatures on the strength of frozen sandstone. The crack damage threshold could be treated as an essential intrinsic property for predicting the failure process of frozen sandstones. The results can provide an important reference for the design and construction of frozen ground engineering.
Feng Ming; Shujuan Zhang; Fujun Niu; Zhiwei Zhou. A study on crack damage stress and the damage constitutive model of frozen sandstone. Bulletin of Engineering Geology and the Environment 2021, 80, 6955 -6970.
AMA StyleFeng Ming, Shujuan Zhang, Fujun Niu, Zhiwei Zhou. A study on crack damage stress and the damage constitutive model of frozen sandstone. Bulletin of Engineering Geology and the Environment. 2021; 80 (9):6955-6970.
Chicago/Turabian StyleFeng Ming; Shujuan Zhang; Fujun Niu; Zhiwei Zhou. 2021. "A study on crack damage stress and the damage constitutive model of frozen sandstone." Bulletin of Engineering Geology and the Environment 80, no. 9: 6955-6970.
Many high earth rockfill dams are currently being constructed in the alpine region of Southwest China. Since the effective working time is reduced by the cold climate, it is necessary to solve the problem of intermittent filling of the core wall at low temperature. However, freeze–thaw (FT) cycles in the filling process will change the deformation behavior of gravelly soil. For 300 m-high earth core rockfill dams, the deformation of gravelly soil is a crucial factor in predicting the long-term deformation and settlement after dam construction. To investigate the influence of FT cycles on the deformation characteristics, the deformation of the gravelly soil under different amounts of FT cycles was tested using an MTS-810 test system. The deformation characteristics were discussed, and a modified Burgers model was used to describe the deformation characteristics. The results show that the freeze–thaw action makes the coarse particles break, resulting in an increase in the fine content. The FT cycles can make the creep characteristics of gravelly soil more obvious. The creep strain has a large contribution to the total strain with the increasing in the FT cycles. It is thus suggested that the coverage of thermal insulation material would effectively prevent freezing of the gravelly soil and control the deformation.
Feng Ming; Xiu-Ling Ren; Jin-Guo Wang; Zhi-Wei Zhou; En-Long Liu; Qi-Hao Yu. Effect of freeze–thaw cycles on the deformation behavior of gravelly soil in the 300 m-high earth core rockfill dam. Environmental Earth Sciences 2021, 80, 1 -12.
AMA StyleFeng Ming, Xiu-Ling Ren, Jin-Guo Wang, Zhi-Wei Zhou, En-Long Liu, Qi-Hao Yu. Effect of freeze–thaw cycles on the deformation behavior of gravelly soil in the 300 m-high earth core rockfill dam. Environmental Earth Sciences. 2021; 80 (8):1-12.
Chicago/Turabian StyleFeng Ming; Xiu-Ling Ren; Jin-Guo Wang; Zhi-Wei Zhou; En-Long Liu; Qi-Hao Yu. 2021. "Effect of freeze–thaw cycles on the deformation behavior of gravelly soil in the 300 m-high earth core rockfill dam." Environmental Earth Sciences 80, no. 8: 1-12.
Ice lens is the key factor which determines the frost heave in engineering construction in cold regions. At present, several theories have been proposed to describe the formation of ice lens. However, most of these theories analyzed the ice lens formation from a macroscopic view and ignored the influence of microscopic pore sizes and structures. Meanwhile, these theories lacked the support of measured data. To solve this problem, the microscopic crystallization stress was converted into the macro mean stress through the principle of statistics with the consideration of pore size distribution. The mean stress was treated as the driving force of the formation of ice lens and induced into the criterion of ice lens formation. The influence of pore structure and unfrozen water content on the mean stress was analyzed. The results indicate that the microcosmic crystallization pressure can be converted into the macro mean stress through the principle of statistics. Larger mean stress means the ice lens will be formed easier in the soil. The mean stress is positively correlated with initial water content. At the same temperature, an increase to both the initial water content and the number of pores can result in a larger mean stress. Under the same initial water content, mean stress increases with decreasing temperature. The result provides a theoretical basis for studying ice lens formation from the crystallization theory.
Yuhang Liu; Dongqing Li; Lei Chen; Feng Ming. Study on the Mechanical Criterion of Ice Lens Formation Based on Pore Size Distribution. Applied Sciences 2020, 10, 8981 .
AMA StyleYuhang Liu, Dongqing Li, Lei Chen, Feng Ming. Study on the Mechanical Criterion of Ice Lens Formation Based on Pore Size Distribution. Applied Sciences. 2020; 10 (24):8981.
Chicago/Turabian StyleYuhang Liu; Dongqing Li; Lei Chen; Feng Ming. 2020. "Study on the Mechanical Criterion of Ice Lens Formation Based on Pore Size Distribution." Applied Sciences 10, no. 24: 8981.
Knowledge of the hydraulic conductivity of warm frozen soil is crucial for accurately calculating the deformation of buildings built in permafrost, and the objective of this study is to provide an experimental and theoretical method for obtaining the hydraulic conductivity of warm saturated frozen soil. The permeability experiments were carried out on warm frozen soil in the low temperature rock triaxial testing system, which provides a precise measurement of the water flow rate through the warm frozen soil. Repeated experiments were conducted to verify the validity of the experimental results. Subsequently, based on the experimental results and given the shortcomings of the ice impedance model, the equivalent model was proposed to predict the hydraulic conductivity of saturated frozen soil. The model suggested that saturated frozen soil and unsaturated unfrozen soil with the same liquid water content have the same hydraulic conductivity. To illustrate the validity of the model, the predictions of seven hydraulic conductivity models for unsaturated unfrozen soil were compared with the measured hydraulic conductivity of saturated frozen soil. The results show that the predictions are close to the measured data, which shows the validity of the model. Thus, the hydraulic conductivity of saturated frozen soil can be directly predicted by the hydraulic conductivity model for unsaturated unfrozen soil. The results provide a new method for obtaining the hydraulic conductivity of saturated frozen soil, which can provide a reference for the design and construction of buildings built in permafrost.
Lei Chen; Feng Ming; Xiyan Zhang; Xiaobin Wei; Yuhang Liu. Comparison of the hydraulic conductivity between saturated frozen and unsaturated unfrozen soils. International Journal of Heat and Mass Transfer 2020, 165, 120718 .
AMA StyleLei Chen, Feng Ming, Xiyan Zhang, Xiaobin Wei, Yuhang Liu. Comparison of the hydraulic conductivity between saturated frozen and unsaturated unfrozen soils. International Journal of Heat and Mass Transfer. 2020; 165 ():120718.
Chicago/Turabian StyleLei Chen; Feng Ming; Xiyan Zhang; Xiaobin Wei; Yuhang Liu. 2020. "Comparison of the hydraulic conductivity between saturated frozen and unsaturated unfrozen soils." International Journal of Heat and Mass Transfer 165, no. : 120718.
Engineering practices illustrate that the water phase change in soil causes severe damage to roads, canals, airport runways and other buildings. The freezing point is an important indicator to judge whether the soil is frozen or not. Up to now, the influence of salt on the freezing point is still not well described. To resolve this problem, a series of freezing point tests for saline soil were conducted in the laboratory. Based on the relationship between the freezing point and the water activity, a thermodynamic model considering the excess Gibbs energy was proposed for predicting the freezing point of saline soil by inducing the UNIQUAC (universal quasi-chemical) model. The experimental results show that the initial water content has little influence on the freezing point if the initial water content is higher than the critical water content, while the freezing point decreases with the decrease of the water content if the initial water content is lower than the critical water content. Moreover, it is found that the freezing point is related to the energy status of liquid water in saline soils and it decreases with the increase of the salt concentration. Moreover, the freezing point depression of saline soil is mainly caused by the decrease of water activity. Compared with the other two terms, the residual term, accounting for the molecular interactions, has an obvious influence on the water activity. This result is helpful for understanding how salt concentration affects the freezing point of saline soil and provides a reference for engineering construction in saline soil areas.
Feng Ming; Lei Chen; Dongqing Li; Chengcheng Du. Investigation into Freezing Point Depression in Soil Caused by NaCl Solution. Water 2020, 12, 2232 .
AMA StyleFeng Ming, Lei Chen, Dongqing Li, Chengcheng Du. Investigation into Freezing Point Depression in Soil Caused by NaCl Solution. Water. 2020; 12 (8):2232.
Chicago/Turabian StyleFeng Ming; Lei Chen; Dongqing Li; Chengcheng Du. 2020. "Investigation into Freezing Point Depression in Soil Caused by NaCl Solution." Water 12, no. 8: 2232.
Unfrozen water content has strong control on the permeability, strength and thermal properties of frozen soil. Several techniques have been used to measure unfrozen water content in frozen soil and many models have been developed for its prediction. However, there has been little investigation on the quantitative analysis of the relationship between pressure and unfrozen water content. With the development of artificial ground freezing techniques and deep mining, knowledge of unfrozen water content in frozen soil under high pressure is critical to the stability of the frozen structures. Here, a new predictive model is presented based on the relationship between chemical potential and unfrozen water content and a previous empirical formula. The simulation results are in good agreement with those from laboratory tests. Both the theoretical analysis and the test results indicated that: (a) the pressure applied to frozen soil reduces the freezing point of bulk water and delays the phase change, and (b) unfrozen water content increases with increasing pressure, and at higher pressures the change is greater. The results improve our understanding of the physical and mechanical properties of freezing soil under pressure for artificial ground freezing applications and deep mining engineering.
Feng Ming; Dong-Qing Li; Yu-Hang Liu. A predictive model of unfrozen water content including the influence of pressure. Permafrost and Periglacial Processes 2020, 31, 213 -222.
AMA StyleFeng Ming, Dong-Qing Li, Yu-Hang Liu. A predictive model of unfrozen water content including the influence of pressure. Permafrost and Periglacial Processes. 2020; 31 (1):213-222.
Chicago/Turabian StyleFeng Ming; Dong-Qing Li; Yu-Hang Liu. 2020. "A predictive model of unfrozen water content including the influence of pressure." Permafrost and Periglacial Processes 31, no. 1: 213-222.
Negative temperature curing is a very harmful factor for geopolymer mortar or concrete, which will decrease the strength and durability. The water in the geopolymer mixture may be frozen into ice, and the water content is a crucial factor. The purpose of this paper is to explore the influence of water content on the properties of alkali-activated binders mortar cured at −5 °C. Fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used as binders. Three groups of experiments with different water content were carried out. The prepared samples were investigated through uniaxial compression strength test, Scanning electron microscopy (SEM), and X-ray diffraction (XRD) for the determination of their compressive strength, microstructural features, phase, and composition. The results indicated that, the compressive strength of samples basically maintained 25.78 MPa–27.10 MPa at an age of 28 days; for 90 days, the values reached 33.4 MPa–34.04 MPa. The results showed that lower water content is beneficial to improving the early strength of mortar at −5 °C curing condition, while it has little impact on long-term strength. These results may provide references for the design and construction of geopolymer concrete in cold regions.
Xiaobin Wei; Feng Ming; Dongqing Li; Lei Chen; Yuhang Liu. Influence of Water Content on Mechanical Strength and Microstructure of Alkali-Activated Fly Ash/GGBFS Mortars Cured at Cold and Polar Regions. Materials 2019, 13, 138 .
AMA StyleXiaobin Wei, Feng Ming, Dongqing Li, Lei Chen, Yuhang Liu. Influence of Water Content on Mechanical Strength and Microstructure of Alkali-Activated Fly Ash/GGBFS Mortars Cured at Cold and Polar Regions. Materials. 2019; 13 (1):138.
Chicago/Turabian StyleXiaobin Wei; Feng Ming; Dongqing Li; Lei Chen; Yuhang Liu. 2019. "Influence of Water Content on Mechanical Strength and Microstructure of Alkali-Activated Fly Ash/GGBFS Mortars Cured at Cold and Polar Regions." Materials 13, no. 1: 138.
In cold regions, hydraulic conductivity is a critical parameter for determining the water flow in frozen soil. Previous studies have shown that hydraulic conductivity hinges on the pore structure, which is often depicted as the pore size and porosity. However, these two parameters do not sufficiently represent the pore structure. To enhance the characterization ability of the pore structure, this study introduced fractal theory to investigate the influence of pore structure on hydraulic conductivity. In this study, the pores were conceptualized as a bundle of tortuous capillaries with different radii and the cumulative pore size distribution of the capillaries was considered to satisfy the fractal law. Using the Hagen-Poiseuille equation, a fractal capillary bundle model of hydraulic conductivity for saturated frozen soil was developed. The model validity was evaluated using experimental data and by comparison with previous models. The results showed that the model performed well for frozen soil. The model showed that hydraulic conductivity was related to the maximum pore size, pore size dimension, porosity and tortuosity. Of all these parameters, pore size played a key role in affecting hydraulic conductivity. The pore size dimension was found to decrease linearly with temperature, the maximum pore size decreased with temperature and the tortuosity increased with temperature. The model could be used to predict the hydraulic conductivity of frozen soil, revealing the mechanism of change in hydraulic conductivity with temperature. In addition, the pore size distribution was approximately estimated using the soil freezing curve, making this method could be an alternative to the mercury intrusion test, which has difficult maneuverability and high costs. Darcy’s law is valid in saturated frozen silt, clayed silt and clay, but may not be valid in saturated frozen sand and unsaturated frozen soil.
Lei Chen; Dongqing Li; Feng Ming; Xiangyang Shi; Xin Chen. A Fractal Model of Hydraulic Conductivity for Saturated Frozen Soil. Water 2019, 11, 369 .
AMA StyleLei Chen, Dongqing Li, Feng Ming, Xiangyang Shi, Xin Chen. A Fractal Model of Hydraulic Conductivity for Saturated Frozen Soil. Water. 2019; 11 (2):369.
Chicago/Turabian StyleLei Chen; Dongqing Li; Feng Ming; Xiangyang Shi; Xin Chen. 2019. "A Fractal Model of Hydraulic Conductivity for Saturated Frozen Soil." Water 11, no. 2: 369.
Concrete material has been a choice for the construction structures, even in the cold regions and saline zone. However, these environmental factors have critical damaging effect on the concrete characters. Consequently, this damage will decrease the servicing time of the concrete construction within this environment. In order to evaluate the durability of concrete, the behavior of concrete specimens under the sulfate solution corrosion attacks was studied in this presented work. Two groups of the specimens were immersed into the sulfate solutions with a concentration of 10% and 20%, respectively. The strength development of the specimens under different immersing time was studied. Based on Fick’s law, a steady diffusion equation for sulfate ions in concrete was presented, and the depth of penetration of the attacking sulfate ions was also determined. Based on the depth of penetration and the definition of damage, a damage model for concrete material is developed and a new equation (strength-time) describing the chemical corrosion concrete material is proposed. Results show that the suggested analytical methods can quantify the damage process of concrete under sulfate attack, and the power laws damage developing formula can be used to describe the damage development of the concrete construction subjected to chemical corrosion.
Feng Ming; Yousheng Deng; Dong-Qing Li. Mechanical and Durability Evaluation of Concrete with Sulfate Solution Corrosion. Advances in Materials Science and Engineering 2016, 2016, 1 -7.
AMA StyleFeng Ming, Yousheng Deng, Dong-Qing Li. Mechanical and Durability Evaluation of Concrete with Sulfate Solution Corrosion. Advances in Materials Science and Engineering. 2016; 2016 ():1-7.
Chicago/Turabian StyleFeng Ming; Yousheng Deng; Dong-Qing Li. 2016. "Mechanical and Durability Evaluation of Concrete with Sulfate Solution Corrosion." Advances in Materials Science and Engineering 2016, no. : 1-7.
The aim of this paper is to increase the understanding of ice lens initiation and growth in freezing soil. A model describing the growth process of ice lenses in soils has been established. The model presented here, which considers a series of processes, including heat transfer, water migration, phase change, ice lens formation, soil deformation, is solved by the use of a transient finite element. The simulated results agree with the experimental data. Results show that: (1) Negative pore water pressure occurs in unfrozen areas, this result in the water transfers from the unfrozen zone to the frozen zone and substantial water was stored in the frozen zone which results in oscillation with in water content distributions. (2) Few segregation ice lenses appeared in the fast freezing section, several thin and discontinuous segregation ice lenses appeared in the transitional section, and thick ice lenses appeared in the third phase when the freezing front tended to be stable. (3) Both the consolidation process and the expansion process are in progress during the freezing process, due to the migration of unfrozen water. (4) The frost heave model is composed of two aspects: the coupled heat-mass transport and the growth of ice lens. Numerical modeling is able to represent the development of both the thermal field and ice segregation observed in the physical models.
Feng Ming; Yu Zhang; Dong-Qing Li. Experimental and theoretical investigations into the formation of ice lenses in deformable porous media. Geosciences Journal 2016, 20, 667 -679.
AMA StyleFeng Ming, Yu Zhang, Dong-Qing Li. Experimental and theoretical investigations into the formation of ice lenses in deformable porous media. Geosciences Journal. 2016; 20 (5):667-679.
Chicago/Turabian StyleFeng Ming; Yu Zhang; Dong-Qing Li. 2016. "Experimental and theoretical investigations into the formation of ice lenses in deformable porous media." Geosciences Journal 20, no. 5: 667-679.