Research on Spatial Scale of Fluctuation for the Uncertain Thermal Parameters of Artificially Frozen Soil

Spatial variability of soil parameter distribution is crucial to calculating the pile foundation failure probability. Traditional reliability design methods describe the dispersion degree of soil parameters with their point variance without considering the influence of correlation distance. In this paper, static cone penetration test data of a project site are used, and random field theory is introduced to describe the average spatial characteristics of soil parameters. Then, the method of spatial average is used to calculate the correlation distance of soil parameters in each foundation soil layer. Given the influence of the correlation distance, a variance reduction function is determined to convert point variance to spatial mean-variance and further calculate the failure probability of pile foundation with the Monte Carlo method to study the influence of correlation distance on pile foundation failure probability. Results show that the spatial variability of parameters can be better reflected, and project cost can be reduced by considering the influence of correlation distance during the pile foundation design process. These results lay a foundation for further research on the pile foundation reliability design method.

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“…Many methods are available to calculate correlation distance [21][22][23]. The method of spatial average [24] is used in this paper.…”

Section: Calculation Methods Of Correlation Distancementioning

confidence: 99%

Influence of Correlation Distance of Soil Parameters on Pile Foundation Failure Probability

et al. 2023

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“…Complex urban geological environment and physicochemical action make the physical and mechanical parameters of the cohesive soil layer in the construction area near the subway show strong spatial variability and correlation, and then make the physical and mechanical parameters of soil layer show inherent uncertainty characteristics, which are closely related to ground pressure, osmotic pressure, water content, temperature, and geological structure [13][14][15]. Limited by technical and economic conditions, the actual survey and test data of the physical and mechanical parameters of the cohesive soil layer in the metro proximity construction area are very limited, which belongs to the problem of small samples from a statistical point of view [16,17].…”

Section: Introductionmentioning

confidence: 99%

Reliability Analysis and Risk Assessment for Settlement of Cohesive Soil Layer Induced by Undercrossing Tunnel Excavation

Wang,

Fan,

Wang

et al. 2024

Sustainability

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Due to the complex urban geological environment and physicochemical interactions, the physical and mechanical parameters of the cohesive soil layer in the adjacent construction area show strong spatial variability and correlation. In addition, the actual exploration and test data are very limited because of limited technical and economic conditions. This severely restricts the ability to evaluate the stability of adjacent structures and to prevent and control instability disasters during subway construction. In this study, a generation method of limited sample data for the cohesive soil layer in the adjacent construction area is proposed. The spatial variability and correlation of uncertain mechanical parameters for the clay layer are quantified using incomplete probability data. A calculation method of uncertain settlement for the cohesive soil layer in the adjacent construction area is developed. The distribution fitting tests of settlement characteristics are conducted with different joint distribution functions and correlation structure. A reliability analysis and risk assessment methodology for the settlement of the cohesive soil layer is presented. The reliability value and failure probability induced by undercrossing tunnel excavation are analyzed and predicted. The results show that the bootstrap simulated sampling and random field method can quantify the cohesive soil layer heterogeneity reasonably under limited investigation data. Different joint distribution and correlation structure functions have different effects on the distribution fitting test. The uncertain settlement of the upper center of the tunnel is the largest, and the failure disaster is most likely to occur. The effects of a copula structure and correlation parameter on the failure probability of the cohesive soil layer are sensitive. This research can provide scientific support for public safety and sustainable development in urban subway construction.

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“…The temperature has a direct influence on the strength and thickness of the frozen soil curtain; therefore, the soil temperature is generally used to judge the physical state of the soil in practical engineering [12][13][14]. In order to understand the distribution of the soil temperature field during the construction process of AGF, researchers have conducted extensive research on this issue either based on field monitoring data or finite element software [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Study on Temporal and Spatial Variation in Soil Temperature in Artificial Ground Freezing of Subway Cross Passage

Zou

Xia

et al. 2023

Sustainability

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Temperature is the fundamental variable used in artificial ground freezing (AGF) design to assess the frozen curtain’s state and carry out an analysis of its mechanical behavior. Therefore, it is important to appropriately understand the temperature variation in the soil during freezing and thawing throughout the construction process of AGF. In this paper, a soil physical state analysis model was established to obtain the one-dimensional distribution curve of the soil temperature field and the temperature variation curve of the soil with temporal, which can be used to explore the soil temperature characteristics during the construction of AGF, so as to scientifically evaluate the physical state of frozen soil and reduce the construction risk. The soil can be divided into three zones during the construction process of AGF, namely the frozen zone, the frozen fringe, and the unfrozen zone. Additionally, Hangzhou muddy silty clay was selected for the indoor model test to verify the correctness of the analytical model. The results show the following: (1) Due to the influence of the latent heat of the phase change, the physical state and temperature of the soil on both sides of the frozen fringe are not the same. It is not appropriate to use the same temperature index to judge whether the soil is frozen or thawed in the project. (2) For Hangzhou muddy silty clay, the freezing index is −1 °C, and the thawing index is 0.9 °C. The research results can provide some guidance for the judgment of the soil state during the AGF of subway cross passages.

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Research on Spatial Scale of Fluctuation for the Uncertain Thermal Parameters of Artificially Frozen Soil

Cited by 3 publications

References 33 publications

Influence of Correlation Distance of Soil Parameters on Pile Foundation Failure Probability

Influence of Correlation Distance of Soil Parameters on Pile Foundation Failure Probability

Reliability Analysis and Risk Assessment for Settlement of Cohesive Soil Layer Induced by Undercrossing Tunnel Excavation

Study on Temporal and Spatial Variation in Soil Temperature in Artificial Ground Freezing of Subway Cross Passage

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