Energy-Driven Damage Constitutive Model of Water-Bearing Coal Under Triaxial Compression

The backfill area of tunnel projects may deform or collapse due to the cyclic disturbance of groundwater and train loads. Hence, the anti-deformation and crack resistance performance of backfill materials under cyclic disturbance is critical to engineering safety. In this paper, concrete was produced by mixing 0.85 mm, 1–3 mm and 3–6 mm rubber particles instead of 10% sand, and tested to discuss the effect of rubber particle size on the deterioration of concrete material properties (compressive characteristics and energy dissipation) after bearing cyclic loading. The stress–strain curve and various parameters obtained through the uniaxial compression test and cyclic load test were used to explore the optimal grain size that can be applied to the tunnel engineering backfill area, and numerical simulation was adopted to calculate the deformation of the surrounding rock and the structural stress of different backfill materials. Research shows that the increase in particle size lessens the compressive strength, deformation resistance and cracking resistance of specimens, but after the cyclic loading test, the concrete material deterioration analysis indicates that rubber concrete has lesser and more stable losses compared to ordinary concrete, so the optimum rubber particle size is 0.85 mm. Numerical calculations show that RC-1 reduces the arch top displacement by 0.4 mm, increases the arch bottom displacement by 0.6 mm and increases the maximum principal stress by 11.5% compared to OC. Therefore, rubber concrete can ensure the strength and stability requirements of tunnel structures, which can provide a reference for similar projects.

Section: Energy Dissipation Featurementioning

confidence: 99%

Fatigue Damage of Rubber Concrete Backfill at Arch Springing Influence on Surrounding Rock Deformation in Tunnel Engineering

Wu,

Zhu,

Liu

et al. 2024

“…The gas desorption characteristics in coal seams are affected by such factors as the coal structure, ground stress, gas pressure, and moisture [3,4]. The factors affecting the gas desorption state of coal bodies under complex conditions have been widely investigated by many Chinese and foreign experts and professors, and abundant results have been achieved [5][6][7][8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Study on the Influence of Gas Desorption Characteristics of Different Coal Bodies under Hydraulic Permeability Enhancement

Ma,

Zhang,

Cao

et al. 2023

To investigate the influence of hydraulic permeability enhancement on the gas desorption and accumulation characteristics of water-bearing coal bodies and deeply implement hydraulic fracturing measures to prevent and control gas disasters in coal seams, isothermal adsorption/desorption tests, low-pressure CO2 adsorption tests, and X-ray diffraction (XRD) tests were performed on anthracite from Anbao Coal Mine in Guizhou and bituminous coal from Huainan Pan’er Coal Mine. The study results showed that the gas desorption by kinds of water-bearing coal samples (anthracite) and bituminous coal (PE) was evidently promoted by stress. After each stress path, differences were observed between coal samples in gas desorption, which, however, presented similar variation trends. The gas desorption of the AB coal samples was greater than that of PE coal samples, and the increment of the limiting gas desorption by the AB coal samples was greater than that by the PE coal samples. The specific surface area of the AB coal samples was larger than that of the PE coal samples, and they both contained hydrophilic minerals and moisture. It was found through field observation that after hydraulic permeability enhancement acted upon water-bearing coal, the desorbed gas passively migrated under the stress action. When the coal body was free from the hydraulic stress action, gas started flowing back. The study results reveal the influence of hydraulic permeability enhancement on the accumulated gas desorption characteristics of water-bearing coal, and will be of theoretical and practical engineering significance for the prevention and control of gas disasters in coal seams using hydraulic measures.

“…In the work of a stability assessment of the coal pillars in a CUR, a proper creep model of coal rock is a priority for numerical modeling or calculating works. Currently, the majority of research is focused on how the water content affects coal strength, whereas there is still a lack of studies on the coal creep process in water-immersion conditions [22,23]. In practical engineering, coal pillar dams are often exposed to groundwater immersion for a long period of time, leading to creep under the overburdened rock [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

A Fractional-Order Creep Model of Water-Immersed Coal

Li,

Wanyan,

et al. 2023

The long-term stability of a coal pillar dam is a serious concern for coal mine underground reservoirs because of the creep behavior of coal in complex water immersion and mechanical environments. In order to investigate the characteristics of creep deformation of water-immersed coal and develop a proper creep model, this paper implemented a series of creep experiments of coal via multistage loading at various water-immersion times. The experiment data were analyzed, in terms of immersion-induced damage, elasto-plastic performance, creep behavior, etc., suggesting obvious mechanical properties’ degradation of coal by water. The elastic modulus and peak strength of water-immersed coal decrease exponentially with the immersion time, while the creep rate of coal shows an upward tendency with the promoted immersion time. According to the remarked relationships of elastic, viscoelastic, and viscoplastic properties versus the stress levels and water-immersion time, a creep model based on conformable fractional derivatives is proposed, considering the influence of the water-immersion time and variable stress level. The proposed model was verified using the experiment data, showing a good capacity of the creep model for reproducing the creep process of water-immersed coal. This paper provides a fundamental model for further studying the stability of coal pillars and their influence on the safety of underground water reservoirs.