Large Scale Application of Artificial Ground Freezing

2001 ◽  
Author(s):  
Peter van Dijk ◽  
Jeannette Bouwmeester-van den Bos
Keyword(s):  
Large Scale ◽  
Ground Freezing ◽  
Artificial Ground Freezing

scholarly journals Artificial Ground Freezing Impact on Shear Strength and Microstructure of Granite Residual Soil Under an Extremely Low Temperature

2021 ◽  
Vol 9 ◽  
Author(s):  
Ran An ◽  
Xianwei Zhang ◽  
Lingwei Kong ◽  
Jianwu Gong ◽  
Xuewen Lei
Keyword(s):  
Shear Strength ◽  
Low Temperature ◽  
Magnetic Resonance Image ◽  
Large Scale ◽  
Friction Angle ◽  
Treatment Temperature ◽  
Residual Soil ◽  
Ground Freezing ◽  
Artificial Ground Freezing ◽  
Granite Residual Soil

The Artificial Ground Freezing (AGF) method, which is widely used in tunnel excavations, significantly affects the properties of geotechnical materials in frozen walls under extremely low temperatures. In order to simulate the AGF process, the freezing treatment with a temperature of −30°C and thawing treatment temperature of 25°C were performed on natural specimens of granite residual soil (GRS). Subsequently, triaxial (TRX) tests were conducted to evaluate mechanical properties and Nuclear Magnetic Resonance Image (NMRI) tests were applied to detect pore distributions of GRS. To clarify variations of microstructure after freezing-thawing, the relaxation time (T2) distribution curves and T2-weighted images from NMRI results were thoroughly analyzed from the perspective of quantization and visualization. Results show that the shear strength as well as the cohesion of GRS are reduced sharply by the AGF process, while the internal friction angle decreases gently. The pore size distribution (PSD) converted from the T2 curve is constituted of two different peaks, corresponding to micro-pores with diameters from 0.1 to 10 µm and macro-pores with diameters from 10 to 1,000 µm. Under the AGF impact, the expansion in macro-pores and shrinkage in micro-pores simultaneously exist in the specimen, which was verified from a visualized perspective by T2-weighted images. The frost heaving damage on shear strength is attributed to the microstructural disturbance caused by the presence of large-scale pores and uneven deformations in GRS, which is subjected to the AGF impact under an extremely low temperature.

scholarly journals Analysis of Ground Movement during Large-Scale Pipe Roof Installation and Artificial Ground Freezing of Gongbei Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Xiao-qi Zhou ◽  
Jian-li Pan ◽  
Yang Liu ◽  
Cai-cheng Yu
Keyword(s):  
Large Scale ◽  
Volume Ratio ◽  
Frozen Soil ◽  
Ground Movement ◽  
Frost Heave ◽  
Ground Settlement ◽  
Soil Thickness ◽  
Ground Freezing ◽  
Artificial Ground Freezing ◽  
Ground Heave

This paper analyzes the vertical ground movement during large-scale pipe roof installation and artificial ground freezing of Gongbei tunnel of the Hong Kong-Zhuhai-Macau bridge project. The transverse ground settlement during pipe roof installation is analyzed. The ground loss volume ratio and settlement trough width coefficient during pipe jacking are estimated based on the field measurement of ground settlement. The interaction of pipes during multiple jacking is investigated. The effect of frost heave control by pregrouting, limiting frozen soil thickness, and combination of the two methods is evaluated. The analysis shows that the ground settlement during pipe roof installation by jacking 37 pieces of 1620 mm steel pipes is relatively small with a maximum value of 2.2 cm. The reinforcement to ground provided by the fore-jacked pipes reduces the ground loss volume ratio and, consequently, the ground settlement during the follow-up pipe jacking. The artificial ground freezing generates a relatively large ground heave with a maximum value of 7.8 cm. Pregrouting plays a critical role in the frost heave control by reducing the heave by about 33%. Limiting the frozen soil thickness by heating pipes serves as an effective supplement to frost heave control by reducing the heave by about 9%. The combination of the two measures reduces the ground heave by about 42%. Findings from this paper provide valuable reference to the tunnel construction using pipe roof and artificial ground freezing as presupport.

scholarly journals Application of Artificial Ground Freezing Technology in Modern Urban Underground Engineering

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yi Qi ◽  
Jinxun Zhang ◽  
Hao Yang ◽  
Yongwei Song
Keyword(s):  
Water Surface ◽  
Large Scale ◽  
Freezing Process ◽  
Physical Model Test ◽  
Group Effect ◽  
Underground Engineering ◽  
Sandy Gravel ◽  
Freezing Method ◽  
Ground Freezing ◽  
Artificial Ground Freezing

Based on typical water-rich sandy gravel strata in Beijing, in order to explore the application of the artificial ground freezing method (AGF) in urban large-scale underground engineering, the formation and development of freezing body were analyzed when multirow freezing pipes were working together, and the group effect exhibited during the freezing process was also revealed in this paper. On this basis, the basin-shaped freezing method (BFM) is put forward as an application of AGF used in underground engineering. BFM structure consists of two parts: the frozen curtain (basin wall) around the excavation scope and the horizontal frozen body (basin bottom) at the bottom of the station. Physical model test and numerical simulation were conducted to study temperature field expansion of BFM under two different conditions. The results show the following: (1) The group effect refers to the cooling effect of different freezing pipes influencing each other during freezing process. Under the condition of still water, the group effect expands the freezing area, and it shows the gradual development of freezing from back water surface to front water surface under seepage condition. (2) BFM can effectively play the role of water proofing, and although different parts of basin structure show different frozen order under different conditions, both basin wall and basin bottom can form an effective thickness during the freezing process.

Effect of Freeze Pipe Eccentricity in Artificial Ground Freezing Applications

2020 ◽  
Author(s):  
Ahmad F. Zueter ◽  
Minghan Xu ◽  
Mahmoud A. Alzoubi ◽  
Agus P. Sasmito
Keyword(s):  
Energy Consumption ◽  
Radiation Heat Transfer ◽  
Conservation Equation ◽  
Underground Mines ◽  
Phase Front ◽  
Two Phase ◽  
Ground Freezing ◽  
Deep Underground ◽  
Artificial Ground Freezing ◽  
Conjugate Model

Abstract Building concentric tubes is one of biggest practical challenges in the construction of freeze-pipes of artificial ground freezing (AGF) applications for deep underground mines. In this study, the influence of tubes eccentricity on phase-front expansion (i.e., expansion of the frozen body) and energy consumption of AGF systems is analyzed. A 1+1D semi-conjugate model that solves two-phase transient energy conservation equation is derived. The model is firstly validated against experimental data and then verified with a fully-conjugate model from the literature. After that, the model is extended to a field scale of typical deep underground mines to study freeze-pipe eccentricity. The results show that an eccentric freeze pipe can reduce the phase-front expansion by around 25%, as compared with a concentric one. Also, the geometrical profile of the phase-front is significantly influenced by the freeze-pipe eccentricity. Furthermore, in the passive zone, where AGF coolants are isolated from the ground to reduce energy consumption, freeze pipe eccentricity can increase the coolant heat gain by 10%. This percentage can increase up to 200% if radiation heat transfer is minimized.

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