Fractional Stress Relaxation Model of Rock Freeze‐Thaw Damage

Yang

et al. 2023

Preprint

With the continuous promotion of the national western development strategy, as well as the revitalization of the Northeast old industrial base, many water conservation, transportation and mining projects are planned more frequently in permafrost regions at high altitudes and latitudes Rather than conventional geological areas. Because of the periodic changes in air temperature, the properties of geotechnical materials have changed greatly in permafrost regions, resulting in many new geotechnical engineering challenges. It is particularly difficult to evaluate the stability of open pit rock slopes and cutting rock slopes formed by excavation using conventional methods. Based on the theme that the essence of slope stability of fractured rock mass in cold region is the thermo-hydro-mechanical(THM) coupling affected by freeze-thaw cycle, this paper examines the stability of frozen rock slopes from the perspective of the failure mechanisms, types of failures, mechanical properties of low-temperature rock masses. On the base of the study of stability, this paper proposed the classification of frozen rock slopes and a time-varying evaluation method for the stability of frozen rock slope, which takes into account freeze-thaw damage of rock mass, rainfall infiltration in summer and crack propagation in winter, and the numerical simulation method is used for preliminary verification. This paper can deepen scholars' understanding of rock fracture slope in cold area and promote related research work.

Section: Study On Frozen Rock Constitutive Modelmentioning

confidence: 99%

The stability issue of fractured rock mass slope under the influences of freeze-thaw cycle

Yang

et al. 2023

Preprint

“…Various experts and scholars have conducted extensive research on the mechanical properties of rocks at low temperatures and obtained important findings [5][6][7][8][9][10]. Currently, in-depth research is primarily carried out through a combination of theoretical analyses [11], indoor experiments [12], and numerical simulations [13].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Acoustic Emission Characteristics of Thawing Frozen Sandstone

Yang

Liang

Advances in Materials Science and Engineering

et al. 2022

After the construction of a frozen shaft wall is completed, it undergoes a long thawing process. Damage accumulation under load may result in the rupture of the frozen wall and cause engineering accidents. The change in the mechanical properties of the frozen rock during the thawing process is crucial to the stability of the frozen wall. In this study, we selected Cretaceous saturated sandstone as the research object and performed uniaxial compression tests on the frozen sandstone to analyze its mechanical properties during the thawing process. In addition, acoustic emission technology was used to analyze the damage and failure characteristics of the rock. The main findings of the study are as follows: (1) the results of the uniaxial compression tests revealed that the thawing of frozen sandstone comprises five stages. The closure stress, crack initiation stress, expansion strength, and peak strength were obtained from the volumetric stress-strain curve. These four stress values act as the dividing points of the five stages. (2) The initiation stress of frozen sandstone at different temperatures accounts for approximately 50% of the peak strength. The strength value is low, the deformation is large, and it exhibits an obvious strain-softening phenomenon. (3) As the temperature increases, the closure level of the saturated sandstone gradually increases, and the crack initiation and expansion levels gradually decrease. (4) Based on the four characteristic stresses of the thawing process of frozen sandstone, the acoustic emission signal can be divided into a quiet period, an increasing period, a frequent period, a sharp increase period, and a decline period. (5) A frozen sandstone damage model was established based on the D-P failure criterion. The efficacy of the model was evaluated against the test data and was found to be reasonably accurate. This paper uses acoustic emission technology to simultaneously monitor the melting process of frozen rocks and reveal the relationship between intensity and temperature. The results provide theoretical and technical support for evaluating the mechanical damage induced by thawing of a frozen shaft wall.

“…erefore, it is of great signi cance to study the damage and deterioration mechanism of freeze-thaw rock mass in Inner Mongolia to prevent further deterioration of engineering rock mass and understand the development law of freeze-thaw rock mass. e freeze-thaw cycle test of rock is one of the important methods to study the damage mechanism of freeze-thaw [1,2]. Many scholars have made important contributions to the damage and deterioration of rock under the e ect of freezing-thawing.…”

Section: Introductionmentioning

confidence: 99%

Study on Mechanical Properties and Acoustic Emission Characteristics of Sandstone under Freezing and Thawing

Wang

Advances in Materials Science and Engineering

Luo

et al. 2022

The cyclic freezing-thawing action in cold regions leads to the deterioration of rock damage, resulting in local damage and further threatening the safety of engineering. In order to study the degradation characteristics of green sandstone and yellow sandstone under freeze-thaw cycles from macroscopic and microscopic aspects, the sandstone of a mining area in Inner Mongolia was used as experimental material. The freeze-thaw cycles were divided into 20 times, 30 times, and 40 times. NMR images and mechanical test results of two different rock samples were analyzed by binarization, NMR, and mechanical test. The test results show that, except that the mass change is less than that of yellow sandstone, the physical index degradation degree of green sandstone is higher than that of yellow sandstone, and the frost resistance is less than that of yellow sandstone. The change of acoustic emission event rate of green sandstone is mainly in the elastic deformation stage and stable crack propagation stage, and the change of acoustic emission event rate of yellow sandstone is concentrated in the crack closure stage. In the loading process, the energy release trends of the two sandstones are similar; the 30 freeze-thaw cycles are the boundary of brittle-plastic transformation of green sandstone, and the increase of cumulative energy is the most obvious. The research results provide a theoretical basis for studying the rock failure mechanism and improving the stability of rock engineering in cold regions.