Correlation of granite rock properties with longitudinal wave velocity in rock bolt
Introduction
The physico-mechanical properties of rock mass are fundamental factors in the design and construction of mining, tunneling, and stabilizing slopes. The physico-mechanical properties of rocks are typically investigated using rock core samples via laboratory tests. Ultrasonic testing is one of the most widely used nondestructive testing methods to indirectly infer the physico-mechanical properties of a rock by measuring the elastic wave velocity. Therefore, ultrasonic transducers are used to generate and detect elastic waves at a certain frequency, and then the velocity of elastic waves in rock specimens is obtained. Based on the dependence of elastic waves on density and the elastic properties, the elastic wave velocity in rock has been correlated with porosity, density, elastic modulus, uniaxial compressive strength, and weathering degree.1, 2, 3, 4, 5, 6 However, it is difficult to accurately represent the in-situ condition of rock masses based on laboratory tests owing to the stress relief and vibrations generated by extraction and transportation, respectively. Hence, an appropriate method for predicting the physico-mechanical properties of in-situ rock using data measured from field tests is necessitated. Herein, the propagation velocity of longitudinal waves in a rock bolt is proposed as an alternative indicator for predicting in-situ rock properties.
Rock bolts are widely used to reinforce rock masses and improve rock stability in rock engineering or geotechnical engineering, such as mining, tunneling, and excavation. In general, the length of a rock bolt is significantly greater than its diameter. In this regard, longitudinal waves propagate in the rock bolt with both longitudinal and radial motions, and the relevant elastic modulus is the Young's modulus. This longitudinal wave is similarly known as a bar or rod wave. The propagation of longitudinal waves in terms of the Young's modulus is significantly affected by the surrounding materials of the medium. It is well known that the propagation characteristics of longitudinal waves in rock bolts depend on the surrounding rock properties.7, 8, 9 Hence, the prediction of rock properties based on longitudinal waves in rock bolts may be a feasible concept.
The objective of this study was to investigate the feasibility of using longitudinal waves in a rock bolt to predict the properties of surrounding rock masses, as well as to correlate the physico-mechanical properties of a granitic rock with the longitudinal wave velocity in a rock bolt. Laboratory tests were performed on granitic rock specimens acquired from eight different sites in Icheon, Korea, and their physico-mechanical properties were diversified through artificial weathering processes. The measured rock properties were employed in numerical simulations as properties of the rock mass surrounding a rock bolt and correlated with the velocity of the simulated longitudinal waves in the rock bolt. Correlation equations were proposed via regression analyses and validated by calculating the root mean square error (RMSE) and mean absolute percentage error (MAPE) between the estimated and measured values. A t-test was conducted to evaluate the statistical significance of the correlation coefficient. In the remainder of this paper, the theoretical background, materials and methods, results and discussion, and summary and conclusions are presented.
Section snippets
Longitudinal wave velocity in rod
For a longitudinal wave propagation in an elastic continuum whose length is much greater than its cross-sectional dimension (e.g., rods, bars, beams, columns, and pipes), the relevant material stiffness can be used to approximate the Young's modulus (E) instead of the constrained modulus (M). This approximation is excellent if the wavelength (λ) of the longitudinal waves is much greater than the cross-sectional dimension because the propagation of longitudinal waves tends to result in lateral
Rock specimen and sampling
The geology of Icheon in Korea comprises primarily igneous rocks and partially sedimentary rocks, as shown in Fig. 1. Jurassic igneous rocks are distributed throughout most parts of the Icheon and are dominated by biotite granites. Precambrian igneous rocks are widely distributed along the northwestern edge of Incheon and are characterized by biotite gneiss. Quaternary alluvium, which is composed of sedimentary rocks, encompasses certain regions of Icheon. Igneous rock samples without any
Physico-mechanical properties of rock specimens
In this study, rock samples were acquired from four boreholes at sites A–H. Hence, the number of specimens used in the laboratory experiments was 32. However, the properties of the specimens were diversified over 12 stages of the artificial weathering process, resulting in 384 specimens with different properties. The measured physico-mechanical properties of the rock specimens, including the velocities (vp and vs), density (ρ), Young's modulus (E), Poisson's ratio (μ), porosity (η), compressive
Summary and conclusions
This study was conducted to investigate the feasibility of using the vL in rock bolts to predict the physico-mechanical properties of in-situ granitic rocks without performing additional laboratory tests. Granite rocks were acquired from Icheon, Korea, and artificial weathering processes were conducted to obtain rock specimens with different properties. Physico-mechanical rock properties including the elastic wave velocities related to constrained and shear moduli (i.e., vp and vs,
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (NRF-2021R1C1C2005687).
References (72)
- et al.
Correlating sound velocity with the density, compressive strength and Young’s modulus of carbonate rocks
Int J Rock Mech Min Sci
(2004) - et al.
Experimental and numerical studies on group velocity of ultrasonic guided waves in rock bolts with different grouted ratios
Comput Geotech
(2019) - et al.
Monitoring early age properties of cementitious material using ultrasonic guided waves in embedded rebar
J Nondestr Eval
(2017) - et al.
Nondestructive evaluation of steel-concrete composite structure using high-frequency ultrasonic guided wave
Ultrasonics
(2020) - et al.
Influence of microfractures and porosity on the physico-mechanical properties and weathering of ornamental granites
Eng Geol
(2005) - et al.
Behavior of circular stainless steel stub columns internally strengthened by longitudinal carbon steel bars
Eng Struct
(2019) - et al.
Critical embedment length and bond strength of fully encapsulated rebar rockbolts
Tunn Undergr Space Technol
(2016) - et al.
Effects of rock weathering on guided wave propagation in rock bolts
Tunn Undergr Space Technol
(2021) - et al.
Modeling elastic wave propagation in waveguides with the finite element method
NDT E Int
(1999) - et al.
Experimental relation between shear strength under low pressure and S-wave velocity of rock subjected to mechanical weathering
Soils Found
(2019)
Predicting long-term stability of tunnels considering rock mass weathering and deterioration of primary support
Tunn Undergr Space Technol
Weathering of the Oporto granite: geotechnical and physical properties
Catena
Prediction of the mechanical behavior of the Oporto granite using Data Mining techniques
Expert Syst Appl
New weathering classifications for granitic rocks based on geomechanical parameters
Eng Geol
Rock-weathering rates as functions of time
Quat Res
Dynamic elastic tests for rock engineering
Poisson's ratio values for rocks
Int J Rock Mech Min Sci
Correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from Turkey
Eng Geol
Investigating the dependence of shear wave velocity on petrophysical parameters
J Petrol Sci Eng
Relation between uniaxial compressive strength and elastic wave velocity of soft rock
Longitudinal waves propagation in a limestone: the relationship between velocity and density
Rock Mech Rock Eng
A correlation between P-wave velocity, impact strength index, slake durability index and uniaxial compressive strength
Bull Eng Geol Environ
Determinations of correlation relationships between strength and some physical characteristics of rocks
Physical and mechanical properties of serpentinized ultrabasic rocks in NW Turkey
Pure Appl Geophys
Guided Wave Inspection of Embedded Cylindrical Structures
Evaluation of rock bolt integrity using guided ultrasonic waves
Geotech Test J
Wave Motion and Vibration in Continuous Media
Soils and Waves
Wave Propagation in Structures: Spectral Analysis Using Fast Discrete Fourier Transforms
The influence of the boundary conditions on longitudinal wave propagation in a viscoelastic medium
Phys Med Biol
Nongrouted ratio evaluation of rock bolts by reflection of guided ultrasonic waves
J Geotech Geoenviron Eng
Nondestructive integrity evaluation of soil nails using longitudinal waves
J Geotech Geoenviron Eng
Empirical correlation of p-wave velocity to the density of weathered granite
Durability of ornamental stone exposed to various weathering environments in Korea
Effect of salt crystallization on stone durability
Economic and Environmental Geology
Shales as Embankment Materials. Doctoral dissertation
Cited by (8)
Instantaneous nondestructive evaluation of elastic modulus by using knocking ball test on sedimentary and metasedimentary rock slope
2023, Measurement: Journal of the International Measurement ConfederationA machine learning-based strategy for predicting the mechanical strength of coral reef limestone using X-ray computed tomography
2023, Journal of Rock Mechanics and Geotechnical EngineeringEffect of intermittent joint distribution on the mechanical and acoustic behavior of rock masses
2023, Journal of Rock Mechanics and Geotechnical EngineeringAssessment on anisotropy degree and fracture modes for weakly anisotropic sandstone using the acoustic emission technique
2023, Fatigue and Fracture of Engineering Materials and Structures