Study on Temperature Field Evolution and Frozen Wall Closure Judgment Criteria of Inclined Shaft under Inclined Holes Freezing Condition

Zhang, Chi; Zhang, Yu; Yang, Wen‐Jei; Li, Haipeng; Lu, Quan

doi:10.1155/2022/8002667

Cited by 3 publications

(2 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The artificial freezing method in mining and digging has received widespread attention from scholars due to its adaptability to various complex engineering conditions and improvement of safety in construction [1], such as the construction of railways on the Tibetan Plateau and the application and development of coal mine freezing methods for well drilling technology [2]. The freezing method of drilling is the application of artificial refrigeration technology to vertical-or inclined-shaft engineering through the temporary freezing of groundwater to consolidate the stability of the underground coal and rock to reduce the occurrence of collapse accidents during the mining process [3]. However, the kinds of mechanical properties that occur on impact have not been clearly explored.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Multiple Fractalisation of Coal and Rock Failure Subjected to the Coupled Effects of Water, Temperature and Dynamic Loads

Jin,

Sun,

Liu

et al. 2023

Applied Sciences

View full text Add to dashboard Cite

The mechanical properties of water-rich coal and rock in a subzero environment are very different from those at room temperature, which causes many unexpected hazards for projects. In this study, coal and rock samples subjected to the coupled effects of water, temperature, and dynamic loads were taken as the research object, and the discussion was shaped around their mechanical properties. The crack evolution trend and different gradient impact velocities were determined using a split-Hopkinson pressure bar (SHPB). Multiple fractals were based on high-speed digital image correlation (HS-DIC) technology and the quality-screening method; the evolution trend of the surface cracks in the crushing process and the distribution characteristics of the specimen fragments after crushing were examined from the perspective of fractals. This provided a powerful supplement to the existing research system on the problem of mining via the freezing method, and it accounted for the shortcomings of the existing research to a certain extent. In this research, the results mainly showed four points: (1) The coal samples were determined to have a wave velocity between 1.68 and 2.01 km/s, while the rock samples were between 2.24 and 2.61 km/s. Under the same conditions, the rock’s resistance to deformation and damage was greater than that of coal. (2) In the saturated state, the plastic strength of the coal and rock samples was greater than that in the dry state, due to the strengthening of their internal stresses caused by the presence of fissure water. (3) With decreasing temperature, the degree of the dynamic compression factor of coal and rock showed a trend of initially increasing, then decreasing, and then increasing. With the increase in the loading rate, the destruction of the coal and rock was more intense, and the destruction process was accelerated. (4) After the saturated coal and rock samples were frozen, their interiors were affected by the dual factors of contraction under the influence of temperature and expansion under the influence of the freezing expansion force. The internal fissures closed or shrank, and the water in the pores turned into ice, leading to an increase in pore volume.

show abstract

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Multiple Fractalisation of Coal and Rock Failure Subjected to the Coupled Effects of Water, Temperature and Dynamic Loads

Jin,

Sun,

Liu

et al. 2023

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…Chen et al [16] established a large-scale three-dimensional freezing model test bench and studied the temperature field distribution law of the frozen wall of the inclined shaft under the two freezing methods of vertical hole and inclined hole. Zhang et al [17] performed a similarity model test in conjunction with an actual inclined-shaft project, and the evolution law of the temperature field around inclined shafts under freezing conditions was analyzed.…”

Section: Introductionmentioning

confidence: 99%

Temporal and Spatial Evolution Laws of Freezing Temperature Field in the Inclined Shaft of Water-Rich Sand Layers

et al. 2023

View full text Add to dashboard Cite

This study investigated the distribution and evolution characteristics of the temperature field during the freezing and excavation of inclined shafts, with the freezing open-excavation section of Shengfu Mine’s main inclined shaft (located in Shaanxi Province) as the project background. Utilizing field-measured data and the finite element software COMSOL Multiphysics, a 3D freezing temperature-field numerical calculation model was constructed to examine the temporal and spatial evolutions of the temperature field during the construction of the inclined shaft. The findings showed that after 88 days of freezing, the average temperature of the frozen wall in the open-excavation section was below −12 °C. The frozen wall thickness in the sidewalls of different layers exceeded 4 m, and the thickness at the bottom plate exceeded 5 m, meeting the excavation design requirements. For the same freezing time, the average temperature of the frozen wall in the fine sand layer was 0.28 to 2.39 °C lower than that of the frozen wall in the medium sand layer, and its effective thickness was 0.36 to 0.59 m greater than that in the medium sand layer. When the soil was excavated, and the well side was exposed, a phenomenon known as “heat flow erosion” occurred in the soil at the well-side position, causing the well-side temperature to rise. Nevertheless, this increase was generally limited, and when continuous cooling was applied, the well side could maintain a very low negative temperature level. Consequently, there was no spalling phenomenon. The effective thickness of the frozen wall during excavation did not decrease, with the average temperature remaining below −10 °C. Consequently, there was no large-scale “softening” of the frozen wall during excavation, thus ensuring construction safety. The numerical calculation model in this paper can be used to predict the development law of the freezing temperature field of the water–rich sandy layers in Shengfu Mine and adjust the on–site cooling plan in real time according to the construction progress. This research provides valuable theoretical insights for the optimal design and safe construction of freezing inclined-shaft sinking projects.

show abstract

Study on Evolution of the Thermophysical and Mechanical Properties of Inner Shaft Lining Concrete during Construction Period

et al. 2022

View full text Add to dashboard Cite

The asymmetric temperature field is one of the main factors inducing the cracking of the inner shaft lining during freezing-shaft sinking. The evolution equation for the thermophysical and mechanical properties of shaft lining concrete during construction period is the basis for revealing the cracking mechanism. In this study, several experiments were conducted to reveal the evolution of the temperature field, thermal conductivity, specific heat capacity, compressive strength, tensile strength, and elastic modulus of shaft lining concrete with age and lining thickness within the first 7 d after pouring. Results show that the shaft lining concrete temperature curve after pouring can be divided into five stages: induction, slow heating, rapid heating, rapid cooling, and slow cooling. Thermal conductivity and specific heat capacity reached the maximum on Day 1 and gradually decreased with an increase in age. The compressive strength, tensile strength and elastic modulus significantly increased with age. With an increase in thickness, the shaft lining concrete at the same age improved its three mechanical parameters. Finally, the evolution equation for these thermophysical and mechanical parameters with age within the first 7 d after pouring was fitted based on experimental data. This study is expected to provide a thermophysical and mechanical basis for studying the cracking mechanism of the inner shaft lining.

show abstract

Study on Temperature Field Evolution and Frozen Wall Closure Judgment Criteria of Inclined Shaft under Inclined Holes Freezing Condition

Cited by 3 publications

References 18 publications

Experimental Study of the Multiple Fractalisation of Coal and Rock Failure Subjected to the Coupled Effects of Water, Temperature and Dynamic Loads

Experimental Study of the Multiple Fractalisation of Coal and Rock Failure Subjected to the Coupled Effects of Water, Temperature and Dynamic Loads

Temporal and Spatial Evolution Laws of Freezing Temperature Field in the Inclined Shaft of Water-Rich Sand Layers

Study on Evolution of the Thermophysical and Mechanical Properties of Inner Shaft Lining Concrete during Construction Period

Contact Info

Product

Resources

About