scholarly journals An Analytical Solution for the Frost Heaving Force considering the Freeze-Thaw Damage and Transversely Isotropic Characteristics of the Surrounding Rock in Cold-Region Tunnels

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Jiabing Zhang ◽  
Xiaohu Zhang ◽  
Helin Fu ◽  
Yimin Wu ◽  
Zhen Huang ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Transversely Isotropic ◽  
Frost Damage ◽  
Surrounding Rock ◽  
Cold Region ◽  
Frost Heaving ◽  
Power Series Method ◽  
Variable Theory ◽  
Freeze Thaw ◽  
Bedding Angle

Frost damage is a frequent occurrence in cold regions and can threaten the normal use and structural stability of tunnel engineering projects. To accurately determine the frost heaving force and effectively evaluate the frost damage in cold-region tunnels, an analytical solution for the frost heaving force considering the freeze-thaw (F-T) damage and transversely isotropic characteristics of surrounding rock is presented based on complex variable theory and the power series method. The calculation results indicate that the frost heaving force acts on the lining considering that the transversely isotropic characteristics of surrounding rock are significantly greater than those when assuming the surrounding rock is homogeneous isotropic media. This demonstrates that the transversely isotropic characteristics of surrounding rock have a considerable impact on the frost heaving force and should be considered. The frost heaving force continuously increases as the bedding angle increases from 0° to 90°, and the maximum frost heaving force in the Guanjiao tunnel (the rock mass bedding angle is 30°) of the Xining-Geermu Railway in China is approximately 1.04 MPa. In addition, the influence of F-T cycles on the frost heaving force in cold-region tunnels is investigated based on the analytical solution of the frost heaving force proposed in this paper. The frost heaving force acting on the lining decreases with an increasing number of F-T cycles due to the deterioration of the mechanical parameters of the surrounding rock.

Numerical Analysis of Optimization Design for Insulation Layer in Cold Regions Tunnel

2014 ◽  
Vol 1065-1069 ◽  
pp. 368-372 ◽  
Author(s):  
He Song ◽  
Chao Liang Ye ◽  
Jun Feng Mi
Keyword(s):  
Optimization Design ◽  
Frost Damage ◽  
Surrounding Rock ◽  
Temperature Fields ◽  
Insulation Layer ◽  
Cold Region ◽  
Element Analysis ◽  
Penetration Length ◽  
Dimensional Finite Element ◽  
Frost Penetration

Setting of insulation layer is widely recognized to prevent frost damage for tunnels constructed in cold region. Optimization design of insulation layers, however, still need deeply investigate. In this paper, taking Houanshan tunnel as example, two-dimensional finite element analysis on the optimization design of insulation layers has been carried out by ABAQUS. The tunnel temperature fields due to various thickness and length of insulation layer are numerically analyzed. It shows that ,1)4.85°C increased at backside of insulation layer with thickness of 5cm, while 5.8°C increased for thickness of 7cm;2) frozen depth of surrounding rock decrease with the increase of insulation layer thickness. The farther distance to tunnel portal, the smaller thickness of insulation layer required to prevent the surrounding rock from freezing;3)According to analysis, frost penetration length should be 450~500m before tunnel holing-through ,while 720m~830m after tunnel holing-through.

The transversely isotropic poroelastic wave equation including the Biot and the squirt mechanisms: Theory and application

Geophysics ◽  
1997 ◽  
Vol 62 (1) ◽  
pp. 309-318 ◽  
Author(s):  
Jorge O. Parra
Keyword(s):  
Wave Equation ◽  
Fluid Flow ◽  
Analytical Solution ◽  
Seismic Waves ◽  
Transversely Isotropic ◽  
P Wave ◽  
Fluid Properties ◽  
Permeability Anisotropy ◽  
Attenuation And Dispersion ◽  
Maximum Permeability

The transversely isotropic poroelastic wave equation can be formulated to include the Biot and the squirt‐flow mechanisms to yield a new analytical solution in terms of the elements of the squirt‐flow tensor. The new model gives estimates of the vertical and the horizontal permeabilities, as well as other measurable rock and fluid properties. In particular, the model estimates phase velocity and attenuation of waves traveling at different angles of incidence with respect to the principal axis of anisotropy. The attenuation and dispersion of the fast quasi P‐wave and the quasi SV‐wave are related to the vertical and the horizontal permeabilities. Modeling suggests that the attenuation of both the quasi P‐wave and quasi SV‐wave depend on the direction of permeability. For frequencies from 500 to 4500 Hz, the quasi P‐wave attenuation will be of maximum permeability. To test the theory, interwell seismic waveforms, well logs, and hydraulic conductivity measurements (recorded in the fluvial Gypsy sandstone reservoir, Oklahoma) provide the material and fluid property parameters. For example, the analysis of petrophysical data suggests that the vertical permeability (1 md) is affected by the presence of mudstone and siltstone bodies, which are barriers to vertical fluid movement, and the horizontal permeability (1640 md) is controlled by cross‐bedded and planar‐laminated sandstones. The theoretical dispersion curves based on measurable rock and fluid properties, and the phase velocity curve obtained from seismic signatures, give the ingredients to evaluate the model. Theoretical predictions show the influence of the permeability anisotropy on the dispersion of seismic waves. These dispersion values derived from interwell seismic signatures are consistent with the theoretical model and with the direction of propagation of the seismic waves that travel parallel to the maximum permeability. This analysis with the new analytical solution is the first step toward a quantitative evaluation of the preferential directions of fluid flow in reservoir formation containing hydrocarbons. The results of the present work may lead to the development of algorithms to extract the permeability anisotropy from attenuation and dispersion data (derived from sonic logs and crosswell seismics) to map the fluid flow distribution in a reservoir.

Optimization Research of Mix Proportion of Frost Resistance Construction of Concrete Based on the MATLAB Language

2014 ◽  
Vol 584-586 ◽  
pp. 1917-1921
Author(s):  
Jun Jie Zhang ◽  
Rui Hong Shao ◽  
Xiang Yi Meng
Keyword(s):  
Compressive Strength ◽  
Objective Function ◽  
Frost Resistance ◽  
Unit Volume ◽  
Influence Factors ◽  
Multi Objective Optimization ◽  
Cold Region ◽  
Freeze Thaw ◽  
Performance Indexes ◽  
Mix Proportion

Analyze the influence factors of mix proportion affecting concrete freeze-thaw damage. Use the five main performance indexes of the concrete, which are compressive strength, strength of extension, impermeability grade, and frost resistance grade and per unit volume cost concrete, as the objective function of multi-objective optimization equation. Invoke the fgoalattain function in the MATLAB Optimization Toolbox to solve. The optimized parameters of mix proportion of frost resistance construction of unit concrete in cold region are: concrete 1532.6kg, water 910kg, sand 5510.6kg, 5-20mm cobblestone 3747.2kg、20-40mm cobblestone 3658.6kg、40-80mm cobblestone 4733.5kg、80-150mm cobblestone 4738.1kg, and the dosage of water reducing agent is 7.3kg.

scholarly journals EXAMINATION OF FROST DAMAGE RESISTANCE FOR FREEZE-THAW OF LIGHTWEIGHT CONCRETE TYPE 2

2014 ◽  
Vol 20 (46) ◽  
pp. 851-854
Author(s):  
Toshiyuki UEMATSU ◽  
Yasumichi KOSHIRO ◽  
Kenichi ICHISE
Keyword(s):  
Lightweight Concrete ◽  
Frost Damage ◽  
Damage Resistance ◽  
Freeze Thaw ◽  
Concrete Type

Effect of Saturation Degree on Concrete Deterioration due to Freeze-Thaw Action

2011 ◽  
Vol 477 ◽  
pp. 404-408 ◽  
Author(s):  
Wen Cui Yang ◽  
Yong Ge ◽  
Bao Sheng Zhang ◽  
Jie Yuan
Keyword(s):  
Frost Resistance ◽  
Water Pressure ◽  
High Water ◽  
Frost Damage ◽  
Critical Value ◽  
Cold Weather ◽  
Saturation Degree ◽  
Freeze Thaw ◽  
Air Content ◽  
The Difference

Freezing-thawing durability of cement concrete is extremely important in cold weather, to better understand mechanism of frost damage and air-entraining，saturation degree of pores in concrete and its relation with frost resistance were studied in this paper. Concrete specimens with different saturation degree from 0 to 100% were prepared used a sealed tin with a high water pressure pump. Then these specimens were subjected to six freezing-thawing cycles and the relative dynamic modulus of elasticity was examined. The results showed that critical saturation degree of concrete with water- binder ratio of 0.30 and 0.47, air content of 1%, 4% and 6% were from 0.60 to 0.80. When its saturation degree exceeded the critical value, concrete was deteriorated significantly after only six freeze-thaw cycles. The critical saturation degree was mainly related to the air content of concrete mixture, and it decreased with the increasing of air content. The difference between the saturation degree and the critical value can be used to evaluate potential frost resistance of concrete, and its result was consistent with the result of frost tests very well.

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