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 3D MODELLING OF TUNNEL EXCAVATION USING PRESSURIZED TUNNEL BORING MACHINE IN OVERCONSOLIDATED SOILS

2013 ◽  
Vol 35 (2) ◽  
pp. 3-17 ◽  
Author(s):  
Rafik Demagh ◽  
Fabrice Emeriault
Keyword(s):  
Numerical Simulation ◽  
Urban Areas ◽  
Three Dimensional ◽  
Ground Surface ◽  
Tunnel Boring Machine ◽  
Confining Pressure ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Tunnel Boring ◽  
Boring Machines

Abstract The construction of shallow tunnels in urban areas requires a prior assessment of their effects on the existing structures. In the case of shield tunnel boring machines (TBM), the various construction stages carried out constitute a highly three-dimensional problem of soil/structure interaction and are not easy to represent in a complete numerical simulation. Consequently, the tunnelling- induced soil movements are quite difficult to evaluate. A 3D simulation procedure, using a finite differences code, namely FLAC3D, taking into account, in an explicit manner, the main sources of movements in the soil mass is proposed in this paper. It is illustrated by the particular case of Toulouse Subway Line B for which experimental data are available and where the soil is saturated and highly overconsolidated. A comparison made between the numerical simulation results and the insitu measurements shows that the 3D procedure of simulation proposed is relevant, in particular regarding the adopted representation of the different operations performed by the tunnel boring machine (excavation, confining pressure, shield advancement, installation of the tunnel lining, grouting of the annular void, etc). Furthermore, a parametric study enabled a better understanding of the singular behaviour origin observed on the ground surface and within the solid soil mass, till now not mentioned in the literature.

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.

Study on the Frost Heave Characteristics of Artificial Frozen Soil Under Different Freezing Mode

2012 ◽  
Vol 204-208 ◽  
pp. 599-603
Author(s):  
Jun Hao Chen
Keyword(s):  
Structural Design ◽  
Computer Control ◽  
Frozen Soil ◽  
The Self ◽  
Frost Heave ◽  
Test Machine ◽  
Freezing Method ◽  
Artificial Freezing ◽  
Similarities And Differences ◽  
Artificial Freezing Method

At the self-developed DZL-001 computer control of frozen soil frozen-heave test machine, use artificial freezing method carry out vertical and lateral freezing two modes frost heave test of remoulded clay, each mode test includes under no replenishment and replenishment conditions. Monitor the temperature, moisture and frost heave of frozen soil at different location. Compare the similarities and differences of frost heave characteristics of two modes, master the frost heave characteristics of artificial frozen soil. The results provide a certain guidance and reference meaning to layer sidewall structural design.

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 Study on environmental impact of artificial horizontal freezing method in subway connecting passage

2020 ◽  
Vol 198 ◽  
pp. 04023
Author(s):  
Changyi Yu ◽  
Mingyue Lu
Keyword(s):  
Numerical Simulation ◽  
Environmental Impact ◽  
Simulation Method ◽  
Simplified Model ◽  
Thermophysical Parameters ◽  
Freezing Method ◽  
Geological Conditions ◽  
Complex Boundary ◽  
Artificial Freezing ◽  
Artificial Freezing Method

When the subway is built in complex urban strata, especially when excavating near buildings, it is necessary to strictly control the freezing amount by adopting artificial freezing method. At present, the theoretical calculation is aimed at the frozen rise under ideal conditions, but for complex geological conditions, the simplified model results are difficult to meet the actual requirements. However, numerical calculation can adapt to complex strata and complex boundary conditions. Therefore, in this paper, the environmental impact of artificial horizontal freezing method in subway connecting passage is studied by numerical simulation, and the change of thermophysical parameters with the change of temperature field is considered in the simulation. The simulation method in this paper provides guidance for actual construction.

scholarly journals STUDY OF APPLE RESISTANCE TO SPRING FROSTS BY ARTIFICIAL FREEZING METHOD

2019 ◽  
Vol 58 (1) ◽  
pp. 226-232
Author(s):  
Z. E. Ozherelieva ◽  
◽  
N. G. Krasova ◽  
A. M. Galasheva ◽  
◽  
...  
Keyword(s):  
Freezing Method ◽  
Artificial Freezing ◽  
Spring Frosts ◽  
Artificial Freezing Method

Frost heave – pipeline interaction using continuum mechanics

1983 ◽  
Vol 20 (2) ◽  
pp. 251-261 ◽  
Author(s):  
J. F. Nixon ◽  
N. R. Morgenstern ◽  
S. N. Reesor
Keyword(s):  
Continuum Mechanics ◽  
Applied Pressure ◽  
Soil Mass ◽  
Structural Member ◽  
Frozen Soil ◽  
Frost Heave ◽  
Flexible Pipe ◽  
Frozen Ground ◽  
Frost Heaving ◽  
Differential Frost Heave

As a chilled pipeline crosses a transition from frozen to unfrozen ground or shallow permafrost, a differential frost heave problem may develop causing strains in the pipe. Soil–structure interaction models that are currently available to handle this problem concentrate on the pipe as the dominant structural member and represent the soil mass as a series of unconnected springs. This paper considers the soil to be an elastic or nonlinear viscous continuum and imposes a nonlinear boundary condition to represent the frost heaving soil and the dependence of frost heave on applied pressure. The pipe is assumed to be a completely passive structural member and the soil strains at the pipe elevations are studied. The dependence of the maximum pipe strains on the length of the heaving section and on the thickness of frozen ground beneath the pipe have been established for a typical set of soil and frost heaving conditions. It is found that, for the conditions studied, when the thickness of shallow permafrost or frozen soil is greater than about 7–8 m, the strains that a flexible pipe experiences are less than the strain criteria currently in use on many pipeline projects. Keywords: frost heave, pipeline, interaction, stress analysis, finite elements, continuum mechanics, thermo-elasticity.

Passive Cooling of Permafrost Foundation Soils Using Porous Embankment Structures

2000 ◽  
Author(s):  
Douglas J. Goering
Keyword(s):  
Land Surface ◽  
Thermal Characteristics ◽  
Ground Surface ◽  
Element Model ◽  
Passive Cooling ◽  
Frozen Ground ◽  
Foundation Soil ◽  
Dimensional Finite Element ◽  
Permafrost Thawing ◽  
Surface Construction

Abstract Permafrost (permanently frozen ground) underlies approximately 25% of the world’s land surface. Construction of surface facilities in these regions presents unique engineering challenges due to the alteration of the thermal regime at the ground surface. Even moderate disturbance of the pre-existing ground surface energy balance can induce permafrost thawing with consequent settlement and damage to buildings, roadways, or other man-made infrastructure. The present work examines the thermal characteristics of embankments constructed of unconventional, highly porous materials. Using these materials, a passive cooling effect can be achieved due to the unstable density stratification and resulting natural convection that occur during winter months. The convection enhances transport of heat out of the embankment, thus cooling the lower portions of the embankment and underlying foundation soil and preserving the permafrost layer. Numerical results obtained with an unsteady two-dimensional finite element model are compared to experimental measurements taken in full-scale field installations for the cases of open and closed (impermeable) side-slope boundary conditions.

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