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As the increasing demand for deep mineral resource extraction and the construction of deep vertical shafts by the artificial ground freezing method, the stability and safety of shaft that traverse thick alluvial depend significantly on their interaction with the surrounding deep frozen soil medium. Such interaction is directly conditioned by the mechanical properties of the deep frozen soil. To precisely capture these in-situ mechanical properties, the mechanical parameters tests using remodeled frozen specimens cannot ignore the disparities in consolidation history, stress environment and formation conditions between the deep and shallow soils. This study performs a series of long-term high-pressure K0 consolidation (where K0 represents the static earth pressure coefficient, describing the ratio of horizontal to vertical stress under zero lateral strain conditions), freezing under sustained load and unloading triaxial shear tests utilizing remodeled deep clay. This study presents the response of unloading strength and damage properties under varying consolidation stresses, durations, and freezing temperatures. The unloading strength increases sharply and then stabilizes with consolidation time. The unloading strength shows an approximate linear positive correlation with the consolidation stress, while a negative correlation with the freezing temperature. The strengthening rate of the unloading strength due to freezing temperature tends to decrease with increasing consolidation time. Additionally, an improved damage constitutive model was proposed and validated by incorporating the initial K0 stress state and a Weibull-based assumption for damage elements. Based on the back propagation (BP) neural network, a prediction method for the stress-strain curve was offered according to the consolidation stress level, initial stress state, and temperature. These results can provide references for improving the mechanical testing methods of deep frozen clay and revealing differences in mechanical properties between deep and shallow soils.

期刊论文 2025-12-01 DOI: 10.1007/s40948-025-00984-w ISSN: 2363-8419

Studying the dynamic characteristics of frozen clay can offer a useful reference for the design of engineering projects and stability analysis in cold regions. This study conducted several cyclic hollow torsional shear and cyclic triaxial experiments to study the effect of cyclic stress ratios and confining pressures on the stiffness and damping ratio characteristics of frozen clay under the condition of principal stress rotation and fixation. The frozen clay samples tended to undergo progressive failure under principal stress rotation and brittle failure under the fixed direction of the principal stress axis. In addition, the stiffness and damping ratio were significantly more sensitive to dynamic stress amplitude and confining pressure under principal stress rotation. Affected by principal stress rotation, the maximum stiffness attenuation was approximately 10%-20%, whereas the minimum damping ratio measured was approximately 30%-70%. Therefore, the results obtained in this study facilitate a rational understanding of the mechanical behavior of frozen soil under principal stress rotation.

期刊论文 2025-03-01 DOI: 10.1061/JCRGEI.CRENG-704 ISSN: 0887-381X

The macroscopic and microscopic mechanical characteristics of subgrade soil in cold regions play an important role in the stability of embankment engineering in cold regions. In this study, we conduct triaxial tests and isotropic loading -unloading tests on frozen clay in the cold region subgrade. The tests are conducted under different temperatures and confining pressures to obtain its macroscopic strength and deformation characteristics. Meanwhile, we establish a discrete element model of frozen clay based on the Discrete Element Method (DEM) to simulate conventional triaxial and isotropic loading -unloading tests, and analyze its mechanical characteristics from a microscopic perspective. The results of the study indicate that the strength and deformation of frozen clay are greatly affected by the cooling temperature and confining pressure. As the cooling temperature decreases, the cohesion of the specimen significantly increases, and the internal friction angle slightly increases, along with the elastic moduli. Under low confining pressure, the specimen exhibits significant volumetric expansion, while under high confining pressure, the specimen mainly undergoes volumetric contraction. Through discrete element numerical simulation, we obtain the microscopic mechanical characteristics of frozen clay, explain the bulging phenomenon of the specimen from a microscopic perspective, and verify the applicability of the flexible membrane. Meanwhile, the influence rules of various microscopic parameters on the mechanical properties of frozen clay are also obtained through a series of parameter calibration works.

期刊论文 2024-08-01 DOI: 10.1016/j.coldregions.2024.104250 ISSN: 0165-232X

In order to study the soil seasonal dynamic characteristics in the regions with four distinct seasons, the soil dynamic triaxial experiments were conducted by considering the environmental temperature range from -30 degrees C to 30 degrees C. The results demonstrate that the dynamic soil properties in four seasons can change greatly. Firstly, the dynamic triaxial experiments were performed to obtain the dynamic stress-strain curve, elastic modulus, and damping ratio of soil, under different confining pressures and temperatures. Then, the experiments also obtain the dynamic cohesion and internal friction angle of the clay under the initial strain, and the changing rule was summarized. Finally, the results show that the dynamic elastic modulus and dynamic cohesion will increase significantly when the clay is frozen; as the temperature continues to decrease, this increasing trend will gradually slow down, and the dynamic damping ratio will go down when the freezing temperature decreases. In this paper, the change mechanism is objectively analyzed, which verifies the reliability of the conclusions obtained from the experiment.

期刊论文 2024-02-25 DOI: 10.12989/gae.2024.36.4.391 ISSN: 2005-307X
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