Creep behaviour analysis of thin spray-on liners

Güner, Doğukan
Thin Spray-on Liner (TSL) is a relatively thin (2–5 mm) and fast-setting liner material used by spraying onto rock surfaces to support underground excavations. Areal support materials that are sprayed onto the rock, such as shotcrete or liners, are able to generate support resistance at small rock deformations and can prevent underground rockfalls from happening in the first place. However, where large ground convergence occurs, the more flexible TSLs may provide superior support over the full range of rock deformations. In this study, the creep behaviour of two TSLs were determined in the laboratory environment. Under constant stress levels, strain-time behaviours of two TSLs were determined up to 2 months of the testing period. For this purpose, dogbone shape test samples were prepared with different curing times (1-2, 7, and 14 days) and were tested under 23 ± 2 °C laboratory conditions according to the ASTM standards. Four different constant stress levels (80%, 60%, 40%, and 20% of the tensile strength) were applied until rupture of the specimens. The resultant correlations are explained using inter-related equations to make a forecast about the service life of the material (creep rupture envelopes) were derived. The proposed correlations may offer an insight into both the effective permanent support time and the strain amount at the liner failure. Experimental data were used to construct viscoelastic and viscoplastic models. A good agreement was generally observed between the presented models and the experimental results.In addition, the developed constitutive stress-strain-time relations were introduced to finite element software ABAQUS with a new subroutine. After verification of the implemented subroutines, the support performance of the TSLs on the global stability in the underground openings has been investigated. As a result of this study, the creep behaviours of TSLs were investigated for the first time in the literature and it has been found that TSLs are extremely sensitive to creep behaviour. The effective block bearing time of TSL’s with different wedge dimension scenarios of underground excavations were determined. As a result of the numerical studies, performed in 4 different representative rock mass squeezing behaviours with different TSL application thicknesses, it was concluded that the effect of TSL on global stability was extremely small.


Creep modelling study of a surface support liner
Güner, Doğukan; Öztürk, Hasan (2018-06-24)
Surface supports are widely used in underground excavations. Since conventional surface support liners have inherently-brittle characteristics and require longer curing period, an alternative support system using polymer based surface support liner, thin spray-on liners (TSLs), has been observed to have a promising ductile and fast-curing potential for underground operations. TSLs can exhibit a good performance for highly-stressed, deep, rock bursting conditions as well when used together with rock bolts an...
Fracture mechanics interpretation of thin spray-on liner adhesion tests
Öztürk, Hasan (2012-04-01)
Thin spray-on liners (TSLs) are relatively thin (2-5 mm) fast setting liner materials that are sprayed onto rock surfaces to support mining excavations. The adhesive strength between a TSL and a rock surface is an important property controlling the design and performance of TSL rock support systems. In this study, direct pull-off TSL adhesion tests were interpreted based on a fracture mechanics approach. An edge crack propagation equation for a generic case (nu not equal 0.5) was derived and the failure mod...
Creep behaviour investigation of a thin spray-on liner
Güner, Doğukan; Öztürk, Hasan (Elsevier BV, 2018-08-01)
Thin spray-on liner (TSL) is a fast-setting multi component polymeric material applied on a rock surface with a thickness of 2-5 mm. TSLs are primarily used as an areal support element in a support system that also incorporates rock bolts. Different laboratory and field tests were performed to understand the support performance of the TSL for underground design. The research described in this paper presents laboratory studies of the tensile creep behaviour of a cement based TSL for the first time in the lit...
Failure analysis of thin spray-on liner coated rock cores
Öztürk, Hasan (2017-09-01)
Thin spray-on liners (TSLs) are surface support materials used in mining and civil engineering projects since 1990s with a wide ranging area of application from bolt/mesh support replacement to pillar reinforcement systems. This study presents the investigation of pillar reinforcement capacity of the TSL coated andesite rock core by compression test to mimic pillar reinforcement effect. The uniaxial compressive strength (UCS), modulus of elasticity (E), and energy absorbance capacity of uncoated and 5 mm co...
Stiffness requirements for wind girders in open-top cylindrical steel tanks
Zeybek, Özer; Topkaya, Cem (2022-07-01)
© 2022 Elsevier LtdAboveground cylindrical storage tanks are very thin shell structures which are prone to buckling when subjected to wind pressure. Both external and internal pressures are developed due to wind action, and the magnitudes of the pressures generally vary around the circumference. A wind girder is generally used in open-top cylindrical tanks to increase their resistance against buckling. The wind girder must have adequate strength and stiffness in order to fulfill its function properly. Widel...
Citation Formats
D. Güner, “Creep behaviour analysis of thin spray-on liners,” Thesis (Ph.D.) -- Graduate School of Natural and Applied Sciences. Mining Engineering., Middle East Technical University, 2020.