scholarly journals Karst Aquifer Water Inflow into Tunnels: An Analytical Solution

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Chong Jiang ◽  
Haixia Han ◽  
Hansong Xie ◽  
Jing Liu ◽  
Zhao Chen ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Permeability Coefficient ◽  
Water Pressure ◽  
Karst Aquifer ◽  
Seepage Force ◽  
Finite Element Software ◽  
Reduction Coefficient ◽  
Pressure Water ◽  
Initial Support ◽  
Secondary Lining

This study gives two new analytical solutions to the tunnel by high-pressure water in the cavern. Firstly, it deals with the analytical solution for the seepage inflow in unsupported karst aquifer tunnels considering the boundary condition. Secondly, it focuses on the study of the seepage force and gives the reduction coefficient of lining water pressure. A comparison of the analytical solution and the finite element software shows a curve relationship as the relevant permeability coefficient β increases. The results show that the analytical solution and numerical solution are consistent. As d increases, β decreases gradually. β increases as r w increases or the grouting circle and initial support become thinner or the secondary lining becomes thicker. In summary, the analytical solution of β can be used to predict the seepage inflow and the seepage force of the actual engineering.

scholarly journals Analytical Solution of Seepage Field in Karst Tunnel

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Chong Jiang ◽  
Han-song Xie ◽  
Jia-li He ◽  
Wen-yan Wu ◽  
Zhi-chao Zhang
Keyword(s):  
Analytical Solution ◽  
Permeability Coefficient ◽  
Complex Function ◽  
Great Influence ◽  
Pressure Head ◽  
Seepage Flow ◽  
Seepage Field ◽  
Karst Tunnel ◽  
Lining Structure ◽  
Initial Support

An analytical solution for the seepage field in water-filled karst tunnel is derived based on the inversion of complex function and groundwater hydraulics theory. The solution considers the distance between the tunnel and the cavern, the size of the cavern, and the properties of the lining structure, such as the permeability coefficient as well as the radius of the grouting ring. This paper also performed numerical simulations for two cases: the application of gravity and the absence of gravity. The numerical solution was obtained to verify the analytical solution, and a good agreement was found. Then, the effect of parameters is discussed in detail, including the distance between the tunnel and the cavern, the radius of the cavern, the grouting ring, and the initial support. The results show that when the radius of the cavern is constant, the pressure head and seepage flow decrease as the distance between the tunnel and the cavern increases. When the distance is constant, the pressure head and seepage flow increase with the increase of the radius of the cavern. In addition, the pressure head and the seepage flow decrease with the increase of the thickness of the grouting ring and decrease with the decrease of the permeability coefficient. As the thickness of the initial support increases, the pressure head gradually increases and the percolation decreases. Furthermore, due to the great influence of the grouting ring and initial support on the pressure head and seepage flow, the thickness and permeability coefficient of the grouting ring and initial support should be taken into account carefully during construction.

Water Pressure Numerical Analysis of Lining Structure in Mountain Tunnel

2011 ◽  
Vol 71-78 ◽  
pp. 4026-4030
Author(s):  
Xing Hua Wang ◽  
Peng Tu
Keyword(s):  
Permeability Coefficient ◽  
Water Pressure ◽  
Tunnel Construction ◽  
Distribution Rule ◽  
Close Relationship ◽  
Lining Structure ◽  
Equivalent Continuum Model ◽  
Pressure Water ◽  
Equivalent Continuum ◽  
Mountain Tunnel

It is hard to control the high pressure water in mountain tunnel construction. Distribution of seepage field, stress field and displacement field of tunnel are analyzed by numerical method with equivalent continuum model. And distribution rule of groundwater in rock, grouting circle and lining are also analyzed. The results of the study show that water pressure behind lining has a close relationship with rock, grouting circle, thickness of lining, permeability coefficient and drainage of tunnel.

scholarly journals Seepage Force on a Buried Submarine Pipeline Induced by a Solitary Wave

2020 ◽  
Vol 8 (5) ◽  
pp. 324
Author(s):  
Meng-Yu Lin ◽  
Li-Jie Wang
Keyword(s):  
Solitary Wave ◽  
Young’S Modulus ◽  
Permeability Coefficient ◽  
Pore Water Pressure ◽  
Young's Modulus ◽  
Water Pressure ◽  
Vertical Force ◽  
Submarine Pipeline ◽  
Seepage Force ◽  
Poroelastic Seabed

In this study, a finite element method was used to establish a two-dimensional numerical model to solve the problem of the Biot equation describing the poroelastic seabed, and to analyze the seepage force on a buried submarine pipeline under the propagation of a solitary wave. The model provides a solution to the displacement of the poroelastic seabed and the variation of the pore-water pressure. By means of numerical simulation, the effects of Young’s modulus and permeability coefficient of the soil on the pore-water pressure and seepage force are discussed. In the simulation of solitary waves passing through fully buried submarine pipelines, numerical results indicate that the smaller the permeability coefficient in dense sandy bed the greater the vertical force acting on the pipeline, and the smaller the permeability coefficient in loose sand bed the smaller the vertical force acting on the pipeline. In general, when the permeability coefficient is large, the smaller the Young’s modulus the more obvious the influence of the vertical force on the pipeline, and when the permeability coefficient is small, the larger the Young’s modulus the more obvious the influence of the vertical force on the pipeline.

Research of Seepage Influence on the Lateral Water-Earth Pressure in Underground Structures

2013 ◽  
Vol 838-841 ◽  
pp. 1663-1666
Author(s):  
Dai Kui
Keyword(s):  
Force Field ◽  
Pressure Field ◽  
Water Pressure ◽  
Earth Pressure ◽  
Underground Structures ◽  
Seepage Force ◽  
Foundation Pit ◽  
Field Coupling ◽  
Pressure Water ◽  
Supporting Structures

Earth pressure field and hydrostatic water pressure field are usually considered for classical earth pressure theories. Nonconsideration of groundwater seepage field is one of the main reasons why measured values of water-earth pressure on supporting structures are generally very different from those calculated values.Under the action of seepage,seepage force changes soil effective stress and affects soil shear strength.Through calculating the interraction of the hindering force field and seepage force field,a multi-field coupling problem is solved, a new calculation expressions on the foundation pit is presented.Key words : multi-field coupling; seepage ; lateral pressure ; water-earth pressure ; hindering force

scholarly journals Grouting Design of Rich Water Tunnels and the Calculation of Distance between Annular Blind Pipes

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Helin Fu ◽  
Pengtao An ◽  
Kai Li ◽  
Guowen Cheng ◽  
Jie Li ◽  
...  
Keyword(s):  
Permeability Coefficient ◽  
Water Pressure ◽  
Drainage System ◽  
Design Parameters ◽  
Seepage Discharge ◽  
Water Seepage ◽  
Lining Structure ◽  
Grouting Reinforcement ◽  
Design Value ◽  
Secondary Lining

The rich water tunnel often uses “water blocking and drainage limiting” waterproofing and drainage systems. On the one hand, the drainage system is set behind the lining to reduce the water pressure. On the other hand, the stratum grouting is used to control the discharge flow of groundwater. In the drainage system, it is important to determine the distance between the annular blind pipes, but there is no clear calculation formula, which leads to the designer often relying on experience. First, the groundwater drainage system is constructed. Based on Darcy’s law and the law of conservation of mass, the formula for calculating the seepage discharge and the seepage pressure with the parameters of annular blind pipe spacing is derived. At the same time, the design parameters of the grouting circle are optimised, and then the formula of annular blind pipe spacing is derived according to the design value of the antiwater pressure of the secondary lining structure and the allowable seepage discharge of the tunnel. Finally, based on the case study of the Hongtu extra-long tunnel under construction, it is verified by field monitoring data. The results show that (1) grouting reinforcement is an important means to reduce water seepage, and tunnel water seepage can be adjusted by changing the thickness and permeability coefficient of the grouting reinforcement circle, in which the thickness of the reinforcement circle should not be too large, and the permeability coefficient should not be less than 1/80 of the surrounding rock permeability coefficient; (2) according to the derived formula, the water pressure of the secondary lining structure decreases in a parabolic manner from the middle of the two rows of annular blind pipes to the place where the annular blind pipes are set; (3) the allowable water seepage of the tunnel and the design value of the water pressure resistance of the lining structure should be considered when determining the distance between annular blind pipes; and (4) based on the derived formula, the distance between the annular blind pipes in the test section of the Hongtu extra-long tunnel is determined to be 8 m.

The Analysis of Soil Slope Transient Seepage Consider the Change of Permeability Coefficient in Rainfall Condition

2012 ◽  
Vol 446-449 ◽  
pp. 1888-1892
Author(s):  
Zhong Ming He ◽  
Yan Qi Qin ◽  
Zhong Xin Cai
Keyword(s):  
Pore Water ◽  
Permeability Coefficient ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rainfall Infiltration ◽  
Water Infiltration ◽  
Soil Slope ◽  
Seepage Field ◽  
Finite Element Software ◽  
Transient Seepage

In order to study the transient seepage field of soil slope when the saturated permeability coefficient changes under rainfall infiltration condition, the finite element software is used to build the numerical analysis model, the influence of slope seepage field and pore water pressure caused by the change of saturated permeability coefficient are emphatically discussed. The results show, under the condition of the certain sustained rainfall strength and rainfall duration, the rain water infiltration rate and infiltration depth are proportional to slope soil saturation permeability coefficient; Pore water pressure along the elevation direction shows the characteristic of “two big heads, among small” under the influence of rainfall infiltration.

scholarly journals Study on Fracture and Permeability Characteristics of Unloading Rock with High Water Pressure

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhi-tao Ma ◽  
Yong-qiang Cui ◽  
Ke-yu Lu ◽  
Dai-fu Song ◽  
Ya-chao Yang
Keyword(s):  
Permeability Coefficient ◽  
Failure Modes ◽  
Water Pressure ◽  
Water Inrush ◽  
High Stress ◽  
High Water ◽  
Permeability Characteristics ◽  
Finite Element Software ◽  
Seepage Characteristics ◽  
High Water Pressure

Research on the damage and seepage characteristics of unloading rock with high water pressure can help to further understand the mechanism of water inrush in deep mine floor and prevent water inrush. This paper used the RFPA2D-flow finite element software to study the failure and seepage characteristics of unloading rock with high water pressure and high stress and comparatively analyzed the failure modes and seepage characteristics of unloading rock with and without water pressure. The effects of different water pressure differences on the failure of unloading rock and the law of seepage were investigated by analyzing the change of acoustic emission and permeability coefficient with stress. The results showed that the unloading rock without water pressure was brittle failure, and the initial damage of the unloading model with water pressure was earlier than that of the model without water pressure and showed greater brittleness, and its cracks first break through at the bottom of the sample with higher osmotic pressure. With the increase in unloading, the permeability of rock increased gradually until it appeared an abrupt change. The failure mode and permeability law of the rock with different water pressure differences were basically the same, but the greater the pressure difference, the smaller the effective unloading capacity when the permeability coefficient changes suddenly, and the greater the possibility of water inrush in the rock.

scholarly journals The Hydromechanical Interplay in the Simplified Three-Dimensional Limit Equilibrium Analyses of Unsaturated Slope Stability

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 73
Author(s):  
Panagiotis Sitarenios ◽  
Francesca Casini
Keyword(s):  
Analytical Solution ◽  
Slope Stability ◽  
Slope Failure ◽  
Failure Modes ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Three Dimensional ◽  
Stability Limit ◽  
Smooth Transition

This paper presents a three-dimensional slope stability limit equilibrium solution for translational planar failure modes. The proposed solution uses Bishop’s average skeleton stress combined with the Mohr–Coulomb failure criterion to describe soil strength evolution under unsaturated conditions while its formulation ensures a natural and smooth transition from the unsaturated to the saturated regime and vice versa. The proposed analytical solution is evaluated by comparing its predictions with the results of the Ruedlingen slope failure experiment. The comparison suggests that, despite its relative simplicity, the analytical solution can capture the experimentally observed behaviour well and highlights the importance of considering lateral resistance together with a realistic interplay between mechanical parameters (cohesion) and hydraulic (pore water pressure) conditions.

scholarly journals Analysis of Tunnel Water Inrush Considering the Influence of Surrounding Rock Permeability Coefficient by Excavation Disturbance and Ground Stress

2021 ◽  
Vol 11 (8) ◽  
pp. 3645
Author(s):  
Helin Fu ◽  
Pengtao An ◽  
Long Chen ◽  
Guowen Cheng ◽  
Jie Li ◽  
...  
Keyword(s):  
Permeability Coefficient ◽  
Water Pressure ◽  
Water Inrush ◽  
Surrounding Rock ◽  
Water Inflow ◽  
Calculation Error ◽  
External Water Pressure ◽  
Ground Stress ◽  
External Water ◽  
Inflow Prediction

Affected by the coupling of excavation disturbance and ground stress, the heterogeneity of surrounding rock is very common. Presently, treating the permeability coefficient as a fixed value will reduce the prediction accuracy of the water inflow and the external water pressure of the structure, leading to distortion of the prediction results. Aiming at this problem, this paper calculates and analyzes tunnel water inflow when considering the heterogeneity of permeability coefficient of surrounding rock using a theoretical analysis method, and compares with field data, and verifies the rationality of the formula. The research shows that, when the influence of excavation disturbance and ground stress on the permeability coefficient of surrounding rock is ignored, the calculated value of the external water force of the tunnel structure is too small, and the durability and stability of the tunnel are reduced, which is detrimental to the safety of the structure. Considering the heterogeneity of surrounding rock, the calculation error of water inflow can be reduced from 27.3% to 13.2%, which improves the accuracy of water inflow prediction to a certain extent.

Analytical solution and evolution process of gas permeability coefficient on typical hard-soft composite coal seam

2021 ◽  
Vol 14 (15) ◽  
Author(s):  
Yikuo Wang ◽  
Hongbao Zhao ◽  
Tong Wu ◽  
Lei Wang ◽  
Jinyu Li ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Coal Seam ◽  
Permeability Coefficient ◽  
Gas Permeability ◽  
Evolution Process ◽  
Soft Composite
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