Experimental Study on Durability of Hybrid Fiber-Reinforced Concrete in Deep Alluvium Frozen Shaft Lining

Yao, Zhishu; Yu, Fanglin; Zhang, Ping; Huang, Xiaoxian

doi:10.3390/cryst11070725

Cited by 10 publications

(5 citation statements)

References 9 publications

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“…Since 2000, deep soil layers, deep pore water-rich rock layers, and complex layers that have both of these have been commonly encountered while developing coal, iron, and other resources in China [1][2][3][4][5][6][7]. For these complex layers, the artificial freezing method is the most commonly used drilling method [8][9][10][11], accounting for over 90%. According to incomplete statistics, China has built over 150 vertical shafts using the freezing method in deep and complex layers in the past 20 However, these deep (freezing depth ≥ 400 m) and large (D ≥ 8 m) vertical shafts often suffered serious water leaks from the inner shaft lining after the frozen wall thawed, as shown in Figure 1 [12,13] Mine Auxiliary Shaft, creating a world record), and the largest frozen bedrock depth Hd has reached 990 m (Gaojiappao Coal Mine West Huifeng Shaft, creating a world record).…”

Section: Introductionmentioning

confidence: 99%

Development and Preliminary Application of Temperature Stress Test Machine for Cast-in-Place Inner Shaft Lining

et al. 2023

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Over the past 20 years, as the depth and diameter of shaft lines increased in China, the cracking and water leakage of the inner walls of frozen shafts have become increasingly severe, resulting in significant safety threats and economic losses. Understanding the stress variation patterns of cast-in-place inner walls under the combined effects of temperature and constraint during construction is a prerequisite for evaluating the crack resistance performance of inner walls and preventing water leakage in frozen shafts. The temperature stress testing machine is an important instrument for studying the early-age crack resistance performance of concrete materials under the combined effects of temperature and constraint. However, existing testing machines have shortcomings in terms of applicable specimen cross-sectional shapes, temperature control methods for concrete structures, and axial loading capacity. In this paper, a novel temperature stress testing machine suitable for the inner wall structure shape, capable of simulating the hydration heat of the inner walls, was developed. Then, a reduced-scale model of the inner wall according to similarity criteria was manufactured indoors. Finally, preliminary investigations of the temperature, strain, and stress variations of the inner wall under 100% end constraint conditions were conducted by simulating the actual hydration heating and cooling process of the inner walls. Results show that the hydration heating and cooling process of the inner wall can be accurately simulated. After approximately 69 h of concrete casting, the accumulated relative displacement and strain of the end-constrained inner wall model were −244.2 mm and 187.8 με, respectively. The end constraint force of the model increased to a maximum value of 1.7 MPa and then rapidly unloaded, causing the model concrete to crack in tension. The temperature stress testing method presented in this paper provides a reference for scientifically formulating technical approaches to prevent cracking in cast-in-place concrete inner walls.

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Section: Introductionmentioning

confidence: 99%

Development and Preliminary Application of Temperature Stress Test Machine for Cast-in-Place Inner Shaft Lining

et al. 2023

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“…The mine shaft is characterized by large depth, a large cross-sectional area, and complex hydro-geological conditions across strata [3]. The lining constructed to resist external loads, such as the soil and water pressure of a stratum, and maintain the stability of the vertical shaft is called the shaft lining structure [4,5].…”

Section: Introductionmentioning

confidence: 99%

Application of FBG Sensor to Safety Monitoring of Mine Shaft Lining Structure

Yao

et al. 2022

Sensors

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The use of fiber Bragg grating (FBG) sensors is proposed to solve the technical problem of poor sensor stability in the long-term safety monitoring of shaft lining structures. The auxiliary shaft of the Zhuxianzhuang coal mine was considered as the engineering background, and a test system implementing FBG sensors was established to monitor the long-term safety of the shaft lining structure. Indoor simulation testing revealed that the coefficient of determination (r2) between the test curves of the FBG sensor and the resistance strain gauge is greater than 0.99 in both the transverse and vertical strains. Therefore, the FBG sensor and resistance strain gauge test values are similar, and the error is small. The early warning value was obtained by calculation, according to the specific engineering geological conditions and shaft lining structure. The monitoring data obtained for the shaft lining at three test levels over more than three years reveal that the measured vertical strain value is less than the warning value, indicating that the shaft lining structure is currently in a safe state. The analysis of the monitoring data reveals that the vertical strain increment caused by the vertical additional force is approximately 0.0752 με/d. As the mine drainage progresses, the increasing vertical additional force acting on the shaft lining will compromise the safety of the shaft lining structure. Therefore, the monitoring must be enhanced to facilitate decision-making for safe shaft operation.

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“…As the most widely used vertical passage component in underground mines, the strength requirements of shaft lining, which is mainly composed of high-strength concrete, are becoming more and more severe. A lining's brittleness increases with increases in concrete strength [7,8].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Mechanical Properties of High Performance Hybrid Fiber Concrete for Shaft Lining

Zhang

et al. 2021

Applied Sciences

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In order to solve the problem of highly brittle shaft lining under dynamic loading, a combination of hybrid fiber concrete mixed with steel and polypropylene fiber is proposed to make shaft lining. C60, the concrete commonly used in shaft lining, was selected as the reference group. The static mechanical properties, dynamic mechanical properties, and crack failure characteristics of the hybrid fiber concrete were experimentally studied. The test results showed that compared to the reference group concrete, the compressive strength of the hybrid fiber-reinforced concrete did not significantly increase, but the splitting tensile strength increased by 60.4%. The split Hopkinson compression bar results showed that the optimal group peak stress and peak strain of the hybrid fiber concrete increased by 58.2% and 79.2%, respectively, and the dynamic toughness increased by 68.1%. The strain distribution before visible cracks was analyzed by the DIC technology. The results showed that the strain dispersion phenomenon of the fiber-reinforced concrete specimen was stronger than that of the reference group concrete. By comparing the crack failure forms of the specimens, it was found that compared to the reference group concrete, the fiber-reinforced concrete specimens showed the characteristics of continuous and slow ductile failure. The above results suggest that HFRC has significantly high dynamic splitting tensile strength and compressive deformation capacity, as well as a certain anti-disturbance effect. It is an excellent construction material for deep mines under complex working conditions.

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Experimental Study on Durability of Hybrid Fiber-Reinforced Concrete in Deep Alluvium Frozen Shaft Lining

Cited by 10 publications

References 9 publications

Development and Preliminary Application of Temperature Stress Test Machine for Cast-in-Place Inner Shaft Lining

Development and Preliminary Application of Temperature Stress Test Machine for Cast-in-Place Inner Shaft Lining

Application of FBG Sensor to Safety Monitoring of Mine Shaft Lining Structure

Experimental Study on Mechanical Properties of High Performance Hybrid Fiber Concrete for Shaft Lining

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