Study on Preliminarily Estimating Performance of Elementary Deep Underground Engineering Structures in Future Large-Scale Heat Mining Projects

Tang, Min; Hong, Li; Tang, Chun’an

doi:10.1155/2019/3456307

Cited by 10 publications

(4 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The development of deep engineering such as ultradeep drilling, deep laboratory, nuclear waste disposal, and deep resource mining had made temperature of rock increase from 30 °C at a depth of 800 m to 50 °C at a depth of 1500 m approximately [13][14][15][16][17]. In particular, the temperature of the rock had even exceeded 100 °C in some high-temperature tunnels such as Sichuan-Tibet Railway and EGS-E tunnel [18,19]. In the high-temperature environments, the temperature of the grout rose gradually, so its hydration rate was faster than that in the room temperature environment, leading to the decrease of its fluidity.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on Seepage of Chemical Grout Flow in Rock Fracture under Temperature Field

Zhang

Lin

et al. 2022

Geofluids

View full text Add to dashboard Cite

Grouting technology is widely used to improve the mechanical properties and reduce the permeability of the rock in underground engineering. Fluidity is important to promote the grout to be injected into longer fractures, so chemical grouts with low viscosity and adjustable gel time are usually chosen to increase this property. However, the high temperature in some deep engineering leads to a faster hydration rate of the chemical grout than that in the room temperature environment, resulting in the decrease of fluidity. The heat exchange between the grout and the environment is usually ignored in the existing researches, so the aim of the numerical study is therefore to analyse the seepage process of chemical grout in the temperature field, where heat exchange between the grout and environment is considered. A sandstone model with a fracture is established in COMSOL, which is validated using laboratory experiments to confirm the accuracy of the results. The grouting time rises exponentially with the increasing of the flow distance in a single fracture, and a higher environmental temperature leads to a larger grouting time because the gap in the viscosity of the grout at different temperatures enlarges with the increasing hydration time. The effect of the temperature field on the grouting time becomes more significant when the temperature is higher and the hydration time is longer because the viscosity of the grout rises more slowly. The grouting time reduces dramatically when injection pressure is raised because an increasing pressure results in a larger aperture and less hydration time, which is one of the best ways to improve the efficiency of the grouting. The findings of this study can help for better understanding of the seepage process of chemical grout in fractures under high temperature and provide guidance for the selection of chemical grout in grouting engineering.

show abstract

Section: Introductionmentioning

confidence: 99%

Numerical Study on Seepage of Chemical Grout Flow in Rock Fracture under Temperature Field

Zhang

Lin

et al. 2022

Geofluids

View full text Add to dashboard Cite

show abstract

“…According to the development status of traditional EGS, EGS needs to be developed and innovated urgently. In recent years, many scientists at home and abroad have taken a different approach, respectively researching geothermal wells using Iceland's unique geographical advantages to produce supercritical water vapor and using supercritical carbon dioxide as circulating fluid [16][17][18][19] , but none of these schemes can effectively improve the drawbacks of the existing EGS. In this regard, this paper proposes a new concept of enhanced geothermal system-the enhanced geothermal system based on excavation technology (EGS-E), which overcomes the drilling heat recovery technology.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation Research of Excavation Based Enhanced Geothermal System

Liu

et al. 2022

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

Under the premise that the global fossil energy is decreasing, geothermal energy has entered the public view with its huge reserves. Geothermal energy can supply energy stably and uninterruptedly without being restricted by factors such as seasons climates, sunlight changes, and has broad development potential. This paper introduces a new deep geothermal development model—Excavation Based Enhanced Geothermal System (EGS-E). The innovative excavation based EGS-E scheme uses mining techniques to form deep underground access for creating artificial heat reservoir with multi-level fracture networks using excavation, blasting, and caving. The working water enters the heat exchange pool through the shaft for heat exchange. Different from the traditional geothermal model, this model can form an ultra-large volume, high permeability heat source and stable heat storage due to its special structure. In this study, a steady-state 3D model was established to study the heat exchange, temperature at the water outlet, and pressure distribution at the central section of the excavation based enhanced geothermal system (EGS-E). The results show that: when the inlet fluid velocity increases from static to 100m/s, the average outlet fluid temperature decreases from 473.15K to 360K. The heat production is better than that of EGS-D, and it is an ideal alternative to the existing EGS

show abstract

“…Tunnel hazards caused by extremely high/low temperatures, such as freeze-thaw damage in cold regions [1,2] and heat disasters in high-temperature zones [3][4][5], have always been an overwhelming concern [6][7][8]. Installing a reasonable thermal insulation layer (TIL) is widely accepted as an effective method to weaken the heat exchange between the tunnel wall and the airflow [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the variation in mechanical properties of the tunnel rock with changing temperature induced by the ventilation is rarely studied, whether in cold tunnels or high-temperature tunnels [10]. In some high-temperature tunnels, the maximal rock temperature exceeds 200 • C, such as 208 • C in the Sichuan-Tibet Railway and more than 200 • C in the EGS-E (Enhanced Geothermal System-Based Excavation) tunnel (Figure 1), resulting in considerable temperature difference between the airflow and the tunnel rock [3,5]. The rock temperature remarkedly decreases once being ventilated under the cold airflow [3], shrinking the tunnel rock and inducing associated thermal stress.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on Thermal Damage Behavior and Heat Insulation Protection in a High-Temperature Tunnel

Kang

Tang

et al. 2021

Applied Sciences

Self Cite

View full text Add to dashboard Cite

Deepening our understanding of temperature and stress evolution in high-temperature tunnels is indispensable for tunnel support and associated disaster prevention as the rock temperature is remarkably high in hot dry rock (HDR) utilization and similar tunnel engineering. In this paper, we established a two-dimensional thermal–mechanical coupling model through RFPA2D-thermal, by which the temperature and stress field of the surrounding rock in a high-temperature tunnel with and without thermal insulation layer (TIL) were studied, followed by the evolution of thermal cracks. The associated sensitivity analysis of the TIL and airflow factors were then carried out. We found that (1) the tunnel rock is unevenly cooled down by the cold airflow, which induces thermal stress and damages the rock element when it exceeds the tensile strength of the rock mass. Those damaged rock elements accumulate and coalesce into visible cracks in the tunnel rock as the ventilation time goes, reducing the tunnel stability. (2) TIL effectively reduces the heat exchange between the airflow and tunnel rock and weakens the cold shock by the airflow, delaying the crack initiation which provides efficient time to adopt engineering measures for tunnel supporting. (3) TIL parameters are of pivotal importance to the long-term cold shock by the airflow. Increasing the TIL thickness and reducing the TIL thermal conductivity both significantly enhance the thermal insulation effect. The results cover the gap in the study of cold shock in high-temperature tunnels, which is helpful in designs to prevent thermal damage in high-temperature tunnels.

show abstract

Study on Preliminarily Estimating Performance of Elementary Deep Underground Engineering Structures in Future Large-Scale Heat Mining Projects

Cited by 10 publications

References 22 publications

Numerical Study on Seepage of Chemical Grout Flow in Rock Fracture under Temperature Field

Numerical Study on Seepage of Chemical Grout Flow in Rock Fracture under Temperature Field

Numerical Simulation Research of Excavation Based Enhanced Geothermal System

Numerical Study on Thermal Damage Behavior and Heat Insulation Protection in a High-Temperature Tunnel

Contact Info

Product

Resources

About