Loads on Sprayed Waterproof Tunnel Linings in Jointed Hard Rock: A Study Based on Norwegian Cases

Holter, Karl Gunnar

doi:10.1007/s00603-013-0498-0

Cited by 28 publications

(8 citation statements)

References 4 publications

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“…A study of the possible loading of rock support linings based on sprayed concrete and rock bolts from the groundwater and rock mass has been undertaken (Holter 2014). The current practice with the use of rock mass classification according to the Q-system (NGI 2013) normally ensures rock stability with a high factor of safety.…”

Section: Loads From the Rock Massmentioning

confidence: 99%

“…Hence, possible water pressures acting on the tunnel lining need to be considered. A study including monitoring of groundwater pressures around sprayed concrete tunnel linings with drained inverts has been conducted (Holter 2014). These results indicate water pressures lower than the hydrostatic pressure in the immediate vicinity of the tunnel lining.…”

Section: Ground Water Induced Loadsmentioning

confidence: 99%

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Performance of EVA-Based Membranes for SCL in Hard Rock

Holter

2015

Rock Mech Rock Eng

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The bonded property of multi-layered sprayed concrete tunnel linings (SCL) waterproofed with sprayed membranes means that the constituent materials will be exposed to the groundwater without any draining or mechanically separating measures. Moisture properties of the sprayed concrete and membrane materials are therefore important in order to establish the system properties of such linings. Ethyl-vinyl-acetate based sprayed membranes exhibit high water absorption potential under direct exposure to water, but are found to be significantly less hygroscopic and exhibit lower sorptivity (water absorption rate) than sprayed concrete. This material behavior explains the relatively dry in situ condition of the membrane that was observed. Measured in situ moisture content levels of the membrane material in tunnel linings have been found to vary within the range of 30-40 % of the maximum water absorption potential, and show a decreasing trend over the first 4 years after construction has been completed. A model for the mechanical loading, moisture condition and thermal exposure of the membrane and the resulting realistic parameters to be tested is presented. Laboratory testing methods for the membrane materials are evaluated considering possible loads, moisture and freezing exposure. Material testing of membrane materials was conducted with preconditioning to realistic moisture contents and under different temperature conditions including relevant freezing temperatures for tunnel linings. The main effects of the in situ moisture condition of the tested membrane materials are favorable tensile strengths in the range of 1.1-1.5 MPa and low risk of freeze-thaw damage. The crack bridging capacity of the tested membranes is found to be sensitive to temperature. With membrane thicknesses in the range of 3-4 mm, crack bridging capacity up to 4-6 mm opening of the crack width at 23°C and approximately 1 mm opening at -3°C was measured for the tested membranes. No significant reduction of the tensile bond strength could be demonstrated after 35 freeze-thaw cycles with -3°C minimum temperature at the membrane location in the lining. Further work is required to verify the performance of the SCL system under exposure to high hydrostatic pressures and the effects of long term mechanical exposure.

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Section: Loads From the Rock Massmentioning

confidence: 99%

Section: Ground Water Induced Loadsmentioning

confidence: 99%

Performance of EVA-Based Membranes for SCL in Hard Rock

Holter

2015

Rock Mech Rock Eng

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“…Generally, rock bolts are aimed to support the tunnels of motorways or railways for more than 100 years, whereas several months or a year can be enough for requirements of the mine production galleries (Kolymbas 2005;Hoek 2006;Holter 2014;Komurlu and Kesimal 2013).…”

Section: Introductionmentioning

confidence: 99%

Improved Performance of Rock Bolts using Sprayed Polyurea Coating

Komurlu

Kesimal

2014

Rock Mech Rock Eng

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“…Many practices have shown that preserving a certain thickness of the antioutburst layer in actual projects can effectively prevent the occurrence of water inrush disasters. For this reason, many studies have been performed on the issue of tunnel stability or safe rock stratum of water inrush disasters and can be divided into three main categories: empirical analysis [9,10], numerical simulation [11][12][13], and experimental analysis [14]. Gan et al [15] comprehensively considered the perturbation depth of the surrounding rock mass by drilling and blasting, the relaxation thickness of the surrounding rock after tunnel excavation, the expansion of waterbearing fissures under high water pressure, and the rock mass in situ stress state and magnitude.…”

Section: Introductionmentioning

confidence: 99%

Study on the Safety Thickness of Rock Strata for Outburst Prevention in Deep Tunnel Based on Numerical Modeling and Backpropagation Neural Network

et al. 2023

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Water inrush and mud inrush pose a serious threat to safe construction in underground engineering, but it is very difficult to determine the safe distance of outburst prevention rock mass. Based on deep-buried tunnel engineering, this paper proposes a method to determine the safe distance from water inrush disaster between the tunnel and the fault fracture zone. This method combines numerical modeling and backpropagation (BP) neural network. By means of numerical simulation, the internal influence law of the water pressure, lateral pressure coefficient, fault fracture zone width, and tunnel burial depth on the surrounding rock is analyzed. The evolution law of the minimum safe strata thickness under a single variable and the correlation degree between minimum safe strata thickness and various disaster factors are revealed. Based on the BP neural network analysis of the simulation results and the measured data of Wulaofeng Tunnel, the calculated values of safe strata thicknesses of fault fracture zone (F10) were determined. The results show that the thickness of the safe rock strata increases with increasing water pressure, lateral pressure coefficient, fault fracture zone width, and tunnel burial depth. The minimum safe thickness of F10 of the tunnel ranges from 7.1 m to 7.4 m, and 10 m is reserved in the actual project. The calculated results are consistent with the reserved thickness value in the construction. This conclusion can provide a reference for similar projects.

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Loads on Sprayed Waterproof Tunnel Linings in Jointed Hard Rock: A Study Based on Norwegian Cases

Cited by 28 publications

References 4 publications

Performance of EVA-Based Membranes for SCL in Hard Rock

Performance of EVA-Based Membranes for SCL in Hard Rock

Improved Performance of Rock Bolts using Sprayed Polyurea Coating

Study on the Safety Thickness of Rock Strata for Outburst Prevention in Deep Tunnel Based on Numerical Modeling and Backpropagation Neural Network

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