Analytical and experimental assessment of mechanical borehole sealing performance in rock

This paper examines the bond strength of cement grout plugs cast in rock. The bond strength has been determined through push-out testing in which an axial load is applied to cement grout plugs emplaced in boreholes in welded tuff cylinders. The push-out tests have been performed as a function of borehole (plug) radius and plug length. The use of four different borehole radii and three different plug length-to-radius ratios enables the evaluation of size effects. A power law obeying strength decrease with increasing plug radius and decreasing plug length results. The exponents of the power law extrapolation are about 0.5 for the borehole (plug) radius size effects and about 1.1 for the size effects on plug length-to-radius ratio. The mean axial strength, mean bond strength and mean peak shear strength range from 15.0-170 MPa, 3.90-11.0 MPa and 17.0-115 MPa, respectively. The tensile stresses in and near the vicinity of an axially loaded borehole plug are analyzed. Implications of the tensile stresses and peak shear stresses on plug design are discussed. The main conclusion is a recommendation to design friction plugs in shafts, drifts, tunnels, or boreholes with a length-to-radius ratio of at least eight. (C) 1997 Elsevier Science B.V.


Performance assessment of cement grout borehole plugs in basalt
Akgün, Haluk (Elsevier BV, 1994-01-01)
Flow tests have been conducted on expansive cement grout plugs with diameters of 160 mm and 200 mm, and length-to-diameter ratios of one, in boreholes in basalt blocks and in steel pipes. Two types of flow tests have been performed: pseudo-constant head tests and transient pulse tests. Hydration temperatures of cement grout plugs have been monitored in steel pipes with inside diameters ranging from 110 mm to 200 mm. During flow tests, basalt blocks have fractured, presumably due to water injection pressure,...
An empirical method for design of grouted bolts in rock tunnels based on the Geological Strength Index (GSI)
Osgoui, Reza R.; Unal, Erdal (Elsevier BV, 2009-08-14)
The procedure presented in this paper has been developed for the design of grouted rock bolts in rock tunnels during preliminary design stage. The proposed approach provides a step-by-step procedure to set up a series of practical guidelines for optimum pattern of rock bolting in a variety of rock mass qualities. For this purpose, a new formula for the estimation of the rock load (support pressure) is recommended. Due to its wide-spread acceptance in the field of rock engineering, the Geological Strength In...
Residual Shear Strength Measured by Laboratory Tests and Mobilized in Landslides
Mesri, Gholamreza; Huvaj Sarıhan, Nejan (American Society of Civil Engineers (ASCE), 2012-05-01)
Drained residual shear strength measured by multiple reversal direct shear or ring shear tests has been successfully used for over four decades for stability analyses of reactivated landslides in stiff clays and clay shales; A body of literature has accumulated in recent decades, claiming that "healing" or "strength regain" is realized in time on preexisting slip surfaces already at residual condition. In other words, the shear stress required to reactivate a landslide is claimed to be larger than the drain...
Experimental and modelling study on nonlinear time-dependent behaviour of thin spray-on liner
Güner, Doğukan; Öztürk, Hasan (Elsevier BV, 2019-02-01)
Thin spray-on liners (TSLs) are fast-setting multi component polymeric materials applied on rock or coal surface with a thickness of 2-5 mm that have fairly high tensile strength, adhesion, and elongation capabilities. Compared to conventional surface support elements, TSLs with polymer content exhibit different material responses over time. As a matter of fact, the creep behaviour of TSLs under a constant load has a significance for the evaluation of the long term performances of TSLs. This paper investiga...
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...
Citation Formats
H. Akgün, “Analytical and experimental assessment of mechanical borehole sealing performance in rock,” ENGINEERING GEOLOGY, pp. 233–241, 1997, Accessed: 00, 2020. [Online]. Available: