A practical method for predicting ground surface deformation induced by the artificial ground freezing method

2021 ◽  
Vol 130 ◽  
pp. 103925
Author(s):  
Lifu Zheng ◽  
Yongtao Gao ◽  
Yu Zhou ◽  
Ting Liu ◽  
Shuguang Tian
Keyword(s):  
Surface Deformation ◽  
Ground Surface ◽  
Practical Method ◽  
Freezing Method ◽  
Ground Freezing ◽  
Artificial Ground Freezing

scholarly journals Structural Monitoring of Metro Infrastructure during Shield Tunneling Construction

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
L. Ran ◽  
X. W. Ye ◽  
G. Ming ◽  
X. B. Dong
Keyword(s):  
Ground Surface ◽  
Structural Monitoring ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Construction Monitoring ◽  
Infrastructure Monitoring ◽  
Ground Freezing ◽  
Artificial Ground Freezing ◽  
Metro Tunnel ◽  
General Architecture

Shield tunneling construction of metro infrastructure will continuously disturb the soils. The ground surface will be subjected to uplift or subsidence due to the deep excavation and the extrusion and consolidation of the soils. Implementation of the simultaneous monitoring with the shield tunnel construction will provide an effective reference in controlling the shield driving, while how to design and implement a safe, economic, and effective structural monitoring system for metro infrastructure is of great importance and necessity. This paper presents the general architecture of the shield construction of metro tunnels as well as the procedure of the artificial ground freezing construction of the metro-tunnel cross-passages. The design principles for metro infrastructure monitoring of the shield tunnel intervals in the Hangzhou Metro Line 1 are introduced. The detailed monitoring items and the specified alarming indices for construction monitoring of the shield tunneling are addressed, and the measured settlement variations at different monitoring locations are also presented.

scholarly journals In situ monitoring of frost heave pressure during cross passage construction using ground-freezing method

2016 ◽  
Vol 53 (3) ◽  
pp. 530-539 ◽  
Author(s):  
Lei Han ◽  
Guan-lin Ye ◽  
Yuan-hai Li ◽  
Xiao-he Xia ◽  
Jian-hua Wang
Keyword(s):  
Pressure Gauge ◽  
Earth Pressure ◽  
In Situ Monitoring ◽  
Frost Heave ◽  
Freezing Process ◽  
Groundwater Levels ◽  
Freezing Method ◽  
Ground Freezing ◽  
Artificial Ground Freezing

The artificial ground-freezing method has the dual effect of ground reinforcement and waterproof sealing, and the frozen curtain can be designed flexibly. It is widely used in the construction of cross passages for shield tunnels in soft ground with high groundwater levels. However, due to the lack of in situ monitoring data, it remains difficult to determine the frost heave pressure acting upon a tunnel. In this study, based on the use of an anti-freezing pad-type earth pressure gauge, in situ monitoring was carried out to measure the frost heave pressure acting upon tunnel segments during the construction of cross passages for the Shanghai Yangtze River Tunnel. The monitoring results show that the earth pressure acting upon the tunnel could decrease dramatically during freezing, and this kind of decrease can take place suddenly and unpredictably, which can be illustrated using the finite element method. The maximum measured frost heave pressure during freezing and cross passage excavation was approximately 0.2 MPa, which was much smaller than the predicted value. Combining the distribution of temperature in the ground and construction countermeasures, the observed phenomena are mainly related to three factors: water migration during the freezing process, the tunnel–ground interaction, and the countermeasure of pressure release holes. The tunnel showed a horizontal extension–deformation, which was consistent with the releasing frost heave pressure acting upon it.

Properties of Frozen Soils for Cross Passage Construction in Line 1 and 2 of Wuxi Metro

2013 ◽  
Vol 353-356 ◽  
pp. 1662-1665 ◽  
Author(s):  
Xiang Dong Hu ◽  
Yan Guang Han
Keyword(s):  
Mechanical Properties ◽  
Laboratory Tests ◽  
Freezing Point ◽  
Frozen Soil ◽  
Frost Heave ◽  
Soil Test ◽  
Frozen Soils ◽  
Freezing Method ◽  
Ground Freezing ◽  
Artificial Ground Freezing

Artificial ground freezing method (AGF) was applied in cross passage constructing of line 1 and 2 of Wuxi Metro. Mechanical properties of frozen soils such as uniaxial compressive strength, modulus of elasticity, Poissons Ratio, frost heave rate and freezing point are prerequisite for design and construction of AGF. In order to obtain the parameters mentioned, laboratory tests were conducted. One was the basic geotechnical test. Another was the frozen soil test.

scholarly journals Factor’s Influence Analysis of Frost Heave during the Twin-Tunnel Construction Using Artificial Horizontal Ground Freezing Method

2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Rong-bao Hong ◽  
Hai-bing Cai ◽  
Meng-kai Li ◽  
Ya-ru Li
Keyword(s):  
Ground Surface ◽  
Frozen Soil ◽  
Frost Heave ◽  
Tunnel Construction ◽  
Displacement Curve ◽  
Finite Element Program ◽  
Freezing Method ◽  
Twin Tunnel ◽  
Ground Freezing ◽  
Clear Distance

In order to analyze the influence of different twin-tunnel parameters on the frost heave of the ground, six tunnel clear distances (0.25 D, 1.00 D, 1.50 D, 2.00 D, 2.50 D, and 3.00 d), three tunnel buried depths (6 m, 12 m, and 18 m), and two freezing orders (simultaneous freezing and sequential freezing) are selected to establish the two-dimensional numerical calculation models, using ABAQUS finite-element program and the user subroutine of frost heaving deformation, and considering the orthotropic deformation characteristics of frozen soil. Numerical simulation results show that the interaction of twin-tunnel freezing is weakened with the increase in tunnel clear distance. Correspondingly, the heaving displacement of the ground surface also decreases. Besides, the heaving displacement curve of the ground surface gradually changes from the unimodal N-type to bimodal M-type as the tunnel clear distance increases. However, the trough of the bimodal M-type curve gradually disappears as the tunnel buried depth increases. SPSS mathematical analysis results show that tunnel clear distance has the highest significance, tunnel buried depth ranks the second, and freezing order ranks the last. It is important to select the appropriate tunnel clear distance during the design of the twin-tunnel construction using the artificial horizontal ground freezing method.

scholarly journals Investigation of Frost-Heaving Characteristics of Horizontal- Cup-Shape Frozen Ground Surface for Reinforced End Soil Mass in Shield Tunnel Construction

2017 ◽  
Author(s):  
Yongxing Zhang ◽  
Ting Zhang ◽  
Ping Yang
Keyword(s):  
Ground Surface ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Frozen Ground ◽  
Frost Heaving ◽  
Freezing Method ◽  
Ground Freezing ◽  
Artificial Freezing ◽  
Shape Frozen ◽  
Artificial Freezing Method

Artificial freezing method is commonly adopted for reinforcingend soil mass of shield tunnel in the weak and rich aqueousformation, which is expected to prevent the construction riskin the originating and arriving of shield machine, whereas thearrangement of freezing pipes is sometimes varied due to variouscomplex limitations, and the corresponding frost-heavingcharacteristics of ground surface also differs from others. Inthis paper, a case of artificial freezing end soil mass with cupshape arrangement of horizontal freezing pipes is studied byfield investigation and numerical analysis, in which a numericalmodel coupled with water-heat-force interactions is proposedfor appropriately evaluating the frost-heaving characteristicsof ground surface in artificial freezing method. Theresults demonstrate that all the considered factors on brinetemperature, buried depth and cup bottom thickness have significantlyinfluences of frost-heaving characteristics of groundsurface in the artificial ground freezing (AGF) with cup shapearrangement of horizontal freezing pipes, in which the frostheave displacement of horizontal-cup-shape frozen groundsurface is increased with the increasing brine temperature andburied depth, whereas that is decreased with the increasing cupbottom thickness.

scholarly journals Advanced ground freezing method and its applications in underground construction

2019 ◽  
Vol 265 ◽  
pp. 04021
Author(s):  
Mikhail Shuplik ◽  
Petr Nikolaev
Keyword(s):  
Urban Areas ◽  
Ground Improvement ◽  
Solid Carbon ◽  
Underground Construction ◽  
Solid Carbon Dioxide ◽  
Freezing Method ◽  
Ground Freezing ◽  
Improvement Method ◽  
Artificial Ground Freezing ◽  
Construction Works

During underground construction works in complex geological environment, special ground improvement techniques have to be used. One of them is artificial ground freezing (AGF). It can be applied in diverse projects in dense populated urban areas that place constraints on an application of other ground improvement methods. In Russia in the late 1980th was developed one new method of ground freezing. It uses solid carbon dioxide (SCD) that is loaded directly into freeze pipes, where it sublimates. As the result, the quite low temperature of freezing can be achieved easily. In this article are discussed several first application cases of this method. The results of these projects allow SCD freezing became widely used ground improvement method in Russia.

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.

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