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 effect of pore-water pressure on NATM tunnel linings in decomposed granite soil

2005 ◽  
Vol 42 (6) ◽  
pp. 1585-1599 ◽  
Author(s):  
J H Shin ◽  
D M Potts ◽  
L Zdravkovic
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Drainage System ◽  
Tunnel Lining ◽  
Natm Tunnel ◽  
Decomposed Granite ◽  
Secondary Lining ◽  
Granite Soil ◽  
Functional Components

Tunnelling in a water bearing soil often produces a long-term interaction between the tunnel lining and the surrounding soil. With respect to lining design, infiltration and external pore-water pressures are often one of the most important factors to be considered. Development of pore-water pressure may accelerate leakage and cause deterioration of the lining. This can be particularly troublesome to structural and functional components of the tunnel and can often lead to structural failure. However, as a result of the complicated hydraulic boundary conditions and the long times often required for pore pressure equilibration, research on this subject is scarce. Consequently, most design approaches deal with the effects of pore-water pressure on the tunnel lining in a qualitative manner. In this paper, the development of pore-water pressure and its potential effects on the tunnel lining are investigated using the finite element method. In particular, the deterioration of a drainage system caused by clogging is considered. It is shown that the development of pore-water pressure on the lining is dependent on the lining permeability and the deterioration of the drainage system, particularly for a tunnel with both a primary and a secondary lining. The magnitude of pore-water pressure on a new Austrian tunnelling method (NATM) tunnel constructed in decomposed granite soil and the effect of tunnel shape are investigated. Design curves for estimating pore-water pressure loads on a secondary lining are proposed.Key words: numerical analysis, tunnel lining, decomposed granite.

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.

Coupled Fluid-Mechanical Analysis of Deep Tunnel in Water-Soaked Karst Stratum

2012 ◽  
Vol 170-173 ◽  
pp. 1744-1748
Author(s):  
Xun Li ◽  
Chuan He ◽  
Guo Wen Xu
Keyword(s):  
Permeability Coefficient ◽  
Water Pressure ◽  
Drainage System ◽  
High Water ◽  
Mechanical Analysis ◽  
Surrounding Rock ◽  
Shield Tunnel ◽  
Deep Tunnel ◽  
Initial Water ◽  
The Impact

To reduce the impact on water resource and the environment, the ‘controlled drainage principle’ is complied with when designing waterproof and drainage system of tunnel in recent years. For deep tunnel in Water-soaked Karst Stratum, the lining would sustain high water pressure that was caused by the unreasonable design of waterproof and drainage system. Taking a railway shield tunnel as an engineering background, the water shut-off effect of grouting circle, minimum controlled discharge of tunnel and the water pressure of lining properties were studied. The results indicated that, under the condition of high initial water pressure and adequate groundwater recharge, to achieve the desired water shut-off effect, the permeability coefficient of grouting circle should be less than that of surrounding rock over one quantitative grade; the water pressure of lining decreased with the increase of discharge, and showed a linear relationship; the lining could meet the requirement on the design water pressure load, when the permeability coefficient of grouting circle less than 1/20 of the surrounding rock’s, and the controlled discharge greater than or equal 1/2 of uncontrolled discharge; the full-sealing waterproof lining would sustain initial water pressure and the calculation value of water pressure couldn’t be discounted, if the grouting wasn’t waterproof.

Numerical Simulation of Grout Curtain in a DEWPR Tunnel

2011 ◽  
Vol 250-253 ◽  
pp. 1873-1876
Author(s):  
Jian Xiu Wang ◽  
Bo Feng ◽  
Pei Wang ◽  
Yi Qun Tang ◽  
Ping Yang
Keyword(s):  
Discharge Rate ◽  
Water Pressure ◽  
Unit Length ◽  
Water Discharge ◽  
Drainage System ◽  
Grout Curtain ◽  
Control Factor ◽  
External Water Pressure ◽  
Grouting Reinforcement ◽  
External Water

Grouting is often adopted in a tunnel to resist high external water pressure; the tunnel is defined as External Water Pressure-Resistant Tunnel (EWPR Tunnel). When the grouting reinforcement does not seal the high pressure groundwater completely and the leakage groundwater is drained by drainage system, the tunnel can be called a Drained External Water Pressure -Resistant Tunnel with limited Drainage (DEWPR Tunnel), the grouting reinforcement and waterproof/drainage system of which are great important and should be considered specially. Take the traffic tunnels of Jinping Second Cascade Hydropower Station as an example, a numerical method is adopted to simulate the influence of grouting reinforcement thickness on the distribution of external water pressure. The results indicate that the discharge rate per unit length is 7.82m2/d with single tunnel drainage and 5.28m2/d with double-tunnel drainage, and the external water pressure can be reduced less than 0.6MPa when the thickness of grouting reinforcement is 12m based on the control factor of volume of water discharge.

Experimental Study on Deformation Properties of Lining Structure of Hydraulic Tunnel

2011 ◽  
Vol 105-107 ◽  
pp. 1320-1325
Author(s):  
Shi Lang Xu ◽  
Wei Shen
Keyword(s):  
Bearing Capacity ◽  
Water Pressure ◽  
Interaction Force ◽  
Surrounding Rock ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Water Seepage ◽  
Deformation Properties ◽  
Lining Structure ◽  
Stress And Deformation

A large-scale indoor model test with water pressure is conducted in order to investigate the stress and deformation properties of reinforced concrete lining structures with circular cross-sections. After lining structure cracks, the stress and deformation of reinforcement in lining structures tend to decrease. Although the interaction force between lining structure and surrounding rock increases with the increase of water pressure, but the ratio of interaction force and water pressure decreases, which reveals that the load-bearing capacity of lining structures decreases, and surrounding rock gradually performs as the primary load-bearing body. The internal water pressure carried by lining structure is about 20%~40% of water pressure before cracking and less than 30% after cracking. Test results illustrate that surrounding rock and inner water seepage significantly influence the stress and deformation properties of lining structure, and inner water seepage is the main reason for the reduction of load-bearing capacity of lining structures.

scholarly journals Distribution Law of Water Pressure on the Lining in Tunnels with Water Blocking and Drainage Control Design

2020 ◽  
Vol 15 (5) ◽  
pp. 749-755
Author(s):  
Hongyuan Huang ◽  
Guoyin Wu ◽  
Yao Rong
Keyword(s):  
Water Pressure ◽  
Complex Function ◽  
Drainage System ◽  
Distribution Law ◽  
Water Blocking ◽  
Mountain Tunnels ◽  
Drainage Capacity ◽  
Secondary Lining ◽  
Composite Lining ◽  
Analytical Expressions

For mountain tunnels in water-rich areas, the water pressure on the lining (WPOL) has a significant impact on the parameter selection and operation safety of the lining. Based on the theory of groundwater dynamics and complex function, this paper derives the analytical expressions of the WPOL and the seepage pressure outside the grouting ring. Under different supporting conditions, the authors analyzed how the WPOL was influenced by the head of groundwater, the permeability of the surrounding rock, and the permeability of the grouting ring. The results show that the permeability of the secondary lining not only affects the drainage capacity of the drainage system, but also greatly impacts the WPOL on the composite lining; the WPOL decreases linearly with the growing drainage capacity. To control the WPOL on the composite lining, designers of mountain tunnels in water-rich areas should carefully plan the water blocking and drainage control in accordance with the surrounding environment.

Fluid-Solid Coupling Numerical Simulation for Tunnel in Fracture Zone Based on 2D-FLAC Software

2012 ◽  
Vol 503-504 ◽  
pp. 167-170
Author(s):  
Jin Xing Lai ◽  
Hao Bo Fan ◽  
Fei Zhou
Keyword(s):  
Ground Water ◽  
Water Pressure ◽  
Drainage System ◽  
Rupture Zone ◽  
Hydraulic Pressure ◽  
Tunnel Structure ◽  
Fault Rupture ◽  
Lining Structure ◽  
Water Blocking ◽  
Tunnel Design

To understand the stressed characteristic of fault rupture zone under high hydraulic pressure, based on the F3 fault of Guanshan tunnel the software 2D-FLAC is adopted to found the fluid-solid coupling numerical model of ground water seepage and evolution in the process of tunnel structure in fault rupture zone under high hydraulic pressure and analyze the mechanical character of tunnel structure in three schemes of whole block, free discharge and limit discharge. The result shows that in the whole block condition, the partial seepage of ground water happened and the lining thickness should be more than 60cm; Regardless of water pressure, the rock is damaged at a large range, and the minimum safety factor of the lining structure meet the tunnel design standard; In the limit discharge condition, the grouting reinforced ring makes the effect of limiting drainage and keeping the tunnel’s stability in the construction. The tunnel drainage gets smaller with the increase of grouting ring’s thickness and the decrease of grouting ring’s penetration parameter; setting the drainage system can decrease the hydraulic pressure at the back of lining as well as grouting and water blocking.

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.

Interaction between water pressure in the basal drainage system and discharge from an Alpine glacier before and during a rainfall-induced subglacial hydrological event

1997 ◽  
Vol 24 ◽  
pp. 288-292 ◽  
Author(s):  
Andrew P. Barrett ◽  
David N. Collins
Keyword(s):  
Water Level ◽  
Water Pressure ◽  
Drainage System ◽  
Water Levels ◽  
Drainage Network ◽  
Alpine Glacier ◽  
Hydraulic Conditions ◽  
Borehole Water ◽  
Progressive Growth ◽  
Resultant Increase

Combined measurements of meltwater discharge from the portal and of water level in a borehole drilled to the bed of Findelengletscher, Switzerland, were obtained during the later part of the 1993 ablation season. A severe storm, lasting from 22 through 24 September, produced at least 130 mm of precipitation over the glacier, largely as rain. The combined hydrological records indicate periods during which the basal drainage system became constricted and water storage in the glacier increased, as well as phases of channel growth. During the storm, water pressure generally increased as water backed up in the drainage network. Abrupt, temporary falls in borehole water level were accompanied by pulses in portal discharge. On 24 September, whilst borehole water level continued to rise, water started to escape under pressure with a resultant increase in discharge. As the drainage network expanded, a large amount of debris was flushed from a wide area of the bed. Progressive growth in channel capacity as discharge increased enabled stored water to drain and borehole water level to fall rapidly. Possible relationships between observed borehole water levels and water pressures in subglacial channels are influenced by hydraulic conditions at the base of the hole, distance between the hole and a channel, and the nature of the substrate.

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.

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