dependent behaviors of rock-concrete interface. Shear strength is determined by the bond strength for bonded shotcrete–rock interfaces under lower normal stress (0.2–0.5 MPa), but largely inﬂuenced by friction under higher normal stress ([1.0 MPa) (Saiang et al. 2005). The similar shear behaviors were also observed by Tian et al. (2015).Cited by: 14Publish Year: 2016Author: Jianjun Tong, Jianjun Tong, Murat Karakus, Mingnian Wang, Congyu Dong, Xinghua Tangsp.info Shear strength characteristics of shotcrete–rock interface ...Sep 19, 2016 · Abstract. The shear behavior of shotcrete–rock interface same as the bond behavior plays a significant role on shotcrete behaviour in a tunnel. The shear strength of shotcrete–rock interface is noticeably affected by high temperature in high rock temperature tunnels. However, there are limited number of studies dedicated to investigate behaviour of shotcrete-rock interface in high …Cited by: 14Publish Year: 2016Author: Jianjun Tong, Jianjun Tong, Murat Karakus, Mingnian Wang, Congyu Dong, Xinghua TangEstimated Reading Time: 13 minssp.info How is the flexural strength of a shotcrete measured?The flexural strength of the FRS is one of the key physical property parameters for ground support design calculations. The RDP test provides design engineers with a measurement of the shotcrete’s peak flexural load at first break. As the shotcrete undergoes further displacement See all results for this questionsp.info What causes a shotcrete shell to break in flexure?As the ground starts to unravel, the shotcrete shell between the bolts is loaded by the dead weight of the loose rock in the mine roof. The shotcrete provides a resistive force, supporting this dead weight load until the weight of the loose rock exceeds the tensile strength of the shotcrete, causing the shotcrete shell to break in flexure.See all results for this question
The surface texture provided on the shotcrete can affect the coating application. A hard, smooth steel trowel finish will tend to be quite slick, and the coating may not bond as well as a floated or sponge finish. A light abrasive blast may be considered to roughen the surface and give more bond.See all results for this questionsp.info Which is the best test for shotcrete loading?A shotcrete testing standard, ASTM 1550-05 round deter- minate panel (RDP) test, was designed to replicate the typical shotcrete loading conditions in a mine or tunnel and gives the best representation and test repeatability. An explanation of the theory behind the round panel test can be reviewed in Johnansen (1972).See all results for this questionsp.info Shear strength characteristics of shotcrete–rock interface ...The shear strength of shotcrete–rock interface is noticeably affected by high temperature in high rock temperature tunnels. However, there are limited number of studies dedicated to investigate ...Estimated Reading Time: 5 minssp.info Shear strength characteristics of shotcrete–rock interface ...Sep 19, 2016 · The shear humidity level, and at 80 u0003C curing temperature when strength of shotcrete–rock interface is noticeably the relative humidity is 95 %. The shear stress- affected by high temperature in high rock temperature displacement curve presents various shapes in the tunnels.
Based on numerous on-site direct shear tests, Andjelkovic et al.  found that the significant effect of adhesion force between concrete and rock surface cannot be ignored; thus, they developed a shear strength model at the contact between rock and concrete, which is significantly different from the rock mass “saw-tooth” model , expressing the shear strength along the discontinuities and …Cited by: 23Publish Year: 2015Author: Vladimir Andjelkovic, Nenad Pavlovic, Zarko Lazarevic, Velimir Nedovicsp.info An Analysis of Flexural Strength and Crack Width for …a large rock mass loads the shotcrete lining to produce a mo-ment that breaks the shotcrete at the mid span near the bolts. The weight of the block mass illustrated in Fig. 2 is held by the shear strength of the shotcrete lining around the block perimeter. This shear failure mode is …sp.info ASSESSING THE MECHANICAL BEHAVIOR OF LARGE …unreinforced shotcrete is stiff and can providehigh initial strength , and it also has the additional benefit of bonding directly with the rock, promoting stability through interface shear strengthand filling of rock fractures [Stacey 2001]. However, unreinforced shotcrete losessp.info Mechanical behavior and constitutive model of shotcrete ...Dec 10, 2020 · The shear force at the interface is transferred from shotcrete to the interior of the surrounding rock by means of tangential stress, which is helpful to form the vaulted compressive stress zone inside the surrounding rock, thus reducing the stress concentration caused by unloading of the surrounding rock.
On the other hand, the shear properties of S rock-shotcrete interface have not attracted so much attention, and only a few tests were performed , including the interfacial shear ...sp.info InfluenceofGroundTemperatureonShotcrete-to-Rock ...Concrete has the characteristics of high compressive strength, high early strength, good durability, and wide ... introduced a test method for testing the shear strength of thin-layer shotcrete and rock contact surfaces ... the adhesion strength of the shotcrete-to …sp.info Influence of Ground Temperature on Shotcrete-to-Rock ...On further research on shotcrete-to-rock adhesion strength, Tong et al. believed that, in high-temperature tunnels, temperature and humidity will indirectly affect the speed and extent of concrete hydration, making rock-concrete interface failure; at this time, the degree of adhesion of the shotcrete-to-rock depends on the roughness of the interface, the rock-concrete interface is ineffective, and …sp.info Technical Questions and Answers Archive - American ...Thus, using the low value of the range with a 150 psi tensile bond strength yields a shear strength of at least 285 psi (2 MPa), well above the 200 psi needed. You may find more information on the bond between concrete and shotcrete layers in the article “ Shotcrete Placed in Multiple Layers does NOT Create Cold Joints ” that can be found in our article archive.
217 10.3.8 Shear Strength of Intact Rock The shear strength is most commonly expressed in terms of the Mohr-Coulomb criterion that is a linear approximation to the strength envelope: = + â where = maximum shear stress (= shear strength) = effective cohesion intercept = effective normal stress = effective stress friction angle The interrelationships between shear strength, uniaxial compressive …sp.info Experimental evaluation of geosynthetics as …Shotcrete strength abstract One of the commonly used stabilization systems for rock tunnels is shotcrete. This ﬁne aggregate mortar is usually reinforced for improving its tensile and shear strength. In deep tunnels, its capacity to absorb energy has been recentlyconsidered for designpurposes, as large displacements of the wall are expected.sp.info 1. IntroductionAn interlayer shear zone is a poor rock mass system with a loose structure, weak mechanical properties, variable thickness, random distribution, strong extension, and high risk due to the shear motion of rock masses via tectonism, resulting in a variety of stability problems and geological hazards. In particular, there is a potential threat to the overall stability of rock masses with interlayer shear zones in large …sp.info Experimental Study of the Shear Strength of Bonded ...The shear strength of the concrete–rock interface is a key factor to justify the stability of a hydraulic structure foundation. The Mohr–Coulomb failure criterion is usually used as shear strength and evaluated by extrapolating shear tests results carried out in a laboratory on small-sized samples. This paper presents an experimental study on the concrete–rock interface shear behavior.
Oct 11, 2021 · In deep roadways, there are mostly big loosen zone, and the support theory is based on the extruded arch and stresses protecting roadway surface by laying reinforcement mesh, shotcrete to prevent the surrounding rock from falling off in pieces, and forming an extruded arch structure with rock bolts and cable bolts, which will improve the shear strength parameters and control stability by …sp.info (PDF) Structural dynamic and stress wave models for the ...There is no known investigation on the adhesive analysis where the rock corresponds to the vibrating ground and strength in shear sad between shotcrete and rock but tests of the the shotcrete layer is the structure of which the response is to be adhesive bond between old concrete and shotcrete is presented determined.sp.info Performance and working mechanism of …Jul 18, 2019 · Researches on the performance and working mechanism of T-anchorage system have been carried out [11, 16, 17]: (1) The excavation of the damaged T-anchorage system can be observed: sites soil and slurry remained intact; slurry–soil interface remained tight; debonding and decoupling occurred at the bolt–slurry interface (Fig. 1).In T-anchorage system, there is a sequential …sp.info State of the Art of the Fibre Reinforced Shotcreteshotcrete support efficiency of rock depends on bond strength between the shotcrete and the rock. The bond strength on different rock surfaces are given in the following table 6 conducted by Prof. U.K. Singh ISM Dhanbad using pull out testing machine. The bond strength is given by
optimized to the existing rock profile. The shotcrete reinforcement comprised lattice girders, steel wire ... strength tests were carried out in accordance with the ... reinforcement spanning the interface was provided. In accordance with the Contract Design, the water- ...sp.info (PDF) Shear-bond strength testing of thin spray-on liners ...A testing method for assessing the shear-bond strength of thin spray-on liner (TSL) on rock substrate was developed at Wits University Rock Mechanics Laboratories. The gap between a 20 mm thick steel ring and a rock core is filled with TSL along thesp.info 10.1016/j.ijrmms.2010.05.006 | DeepDyveJun 11, 2020 · Bandis  discussed a range of studies of the shear behaviour of rock joints as being theoretical or empirical. The theoretical approaches usually utilise numerical methods coupled with advanced constitutive laws to model the behaviour of the joint interface. Although advanced mathematically, these constitutive laws are still empirically ...sp.info Chinese Journal of Underground Space and EngineeringAiming at the ultimate bearing capacity of rock foundation at pile tip of caved rock-socketed pile in karst area,the failure mode of rock foundation at pile tip of caved pile was analyzed in this paper.Based on the shear stress form of Hoek-Brown strength criterion,the calculation method of ultimate bearing capacity of hollowed rock foundation ...
This study analyzes the phenomenon of performance deterioration in fully grouted rock bolts in tunnels with a dry, hot environment and high geothermal activity with a focus on temperature effects on interfacial bond performance. Three groups of fully grouted rock bolt specimens were designed based on similar mechanical principles. They were produced and maintained at 20 °C, 35 °C, and 50 °C.sp.info Failure Patterns and Morphological Soil–Rock Interface ...Prior studies have largely focused on internal components in SRMs such as the rock block proportion, rock size, and rock block shape in terms of macroscopic strength response [7,8,9,10,11,12,13,14].In recent decades, many studies have shown that the soil–rock interface is the weak area inside SRMs at normal temperature and that cracks are typically initiated here.sp.info Pipe flow of pumping wet shotcrete based on lubrication ...Jun 30, 2016 · Wet shotcrete can reduce dust and improve supporting strength, however, safe and efficient pipage is a key technical part of wet shotcrete process. The paper studied the pipe flow law of wet shotcrete based on lubrication layer by build the experimental pumping circuit of wet shotcrete that can carry out a number of full-scale pumping tests.sp.info Geotechnical Engineering Online Library | Geoengineer.orgThis process basically requires many aggregate samples and special instruments, and thus is time-consuming. The main purpose of this research is to evaluate the possibility of estimating the AD characteristics using rock strength tests and to investigate the relationships between AD properties and rock strength tests.
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