Physico-mechanical Properties Of Rocks Research Articles

Prędkość ultradźwiękowa analizy wpływu zawartości wody na kredę fosfatyczną

Water content may have a crucial effect on the petrophysical and mechanical properties of high porosity rocks such as chalk. Consequently, the water fluctuations may significantly influence the behaviour of engineering structures that are constructed in chalks. It is the aim of this study to illustrate how the elastic and strength properties of chalk can evolve considering water content variation using P-wave velocity and analytical analyses. To study the influence of water on the ultrasonic compressional wave velocity (VP), measurements of travel time of three samples subjected to different water content were performed. The Uniaxial Compressive Strength (UCS) in dry and saturated chalk specimens was also estimated. To clarify the possible influence of lithology on the physicomechanical properties of rocks, three samples of phosphatic chalk were studied in thin sections. Automated mineral analysis and textural imaging of the samples were performed using an FEI QEMSCAN®. The analyses of the Ultrasonic tests reveal that changes in the water content are associated with variations in the P-wave velocity. Based on P-wave velocity changes as a function of water content, analytical models have been used to predict the elastic and strength properties. The data indicate that the presence of water significantly reduced the elastic and strength parameters of the chalk, a result that is in agreement with the UCS laboratory tests. The derived equations can be used for predicting the elastic and strength properties of high-porous chalk from the P-wave velocity as a function of water content. This approach may avoid the necessity for time-consuming laboratory testing.

An overview of the applications of soft computing methods for predicting the physico-mechanical properties of rocks from indirect methods

An overview of the applications of soft computing methods for predicting the physico-mechanical properties of rocks from indirect methods

A review study of thermal conductivity and influencing physico-mechanical properties of rocks

A review study of thermal conductivity and influencing physico-mechanical properties of rocks

An Overview of the Applications of Soft Computing Methods for Predicting the Physico-Mechanical Properties of Rocks from Indirect Methods

An Overview of the Applications of Soft Computing Methods for Predicting the Physico-Mechanical Properties of Rocks from Indirect Methods

A Review Study of Thermal Conductivity and Influencing Physico-mechanical Properties of Rocks

A Review Study of Thermal Conductivity and Influencing Physico-mechanical Properties of Rocks

Predicting the brittleness of sandstones from the Leeb hardness test

Brittleness is an important rock property that examines the mechanical behavior and failure properties of rocks in engineering applications. Although there is no standard method for measuring rock brittleness, it can be calculated indirectly as a function of rock mechanical properties based on the rock strength ratio. The aim of this study was to investigate the relationship between the Leeb hardness (HL) values and the brittleness properties of rocks using the simple statistical method. For this purpose, 18 sandstone rock samples were collected and tested in the laboratory to determine the HL and physico-mechanical properties of rocks. In addition, the brittleness properties of rocks were examined with S20 brittleness (BI8) test and five different empirical methods (BI4, BI5, BI11, BI13, and BI14) calculated from rock strength ratios. New models were proposed to predict the brittleness of the rocks, taking into account the HL. Based on the statistical analysis, the proposed models were in good agreement with those measured (for all of the data, R2: 0.76–0.77, for sandstone, R2: 0.78–0.81).

Correlation of granite rock properties with longitudinal wave velocity in rock bolt

Physico-mechanical rock properties are typically investigated via laboratory tests using core samples. However, sample coring is time consuming and expensive. The longitudinal wave velocity in rock bolts embedded in a rock mass depends on the surrounding rock properties. Hence, the longitudinal wave velocity in rock bolts can be utilized to predict rock properties. This study presents the relationship between granite rock properties and longitudinal wave velocity ( v L ) in rock bolts to predict rock properties using the longitudinal wave velocity in a rock bolt. Chemical (saline solution) and mechanical (slake durability test) weathering processes are employed to diversify the properties of the rock specimens. Laboratory tests are conducted on rock specimens to measure the physico-mechanical rock properties, including the velocities ( v p and v s ) associated with constrained and shear moduli , density ( ρ ), Young's modulus ( E ), Poisson's ratio ( μ ), and porosity ( η ), compressive strength ( f c ), and slake durability index ( SDI ). The measured rock properties are used in the rock mass model, and variations in v L in the rock bolt with different properties are investigated via numerical simulations. Results show that v p , v s , ρ , E , and f c are correlated significantly with v L ( R 2 > 0.9), whereas η and SDI are moderately correlated with v L ( R 2 > 0.7). However, a meaningful correlation between μ and v L is not obtained. The root mean square and mean absolute percentage errors are estimated to validate the correlation equations, and errors are not considered. Results of the t -test show that the calculated t -value is higher than the critical t -value, and the p -value is smaller than the significance level of 0.05, indicating that the correlation coefficient is significant. This study shows that the velocity of longitudinal waves in a rock bolt can be a useful indicator for predicting in-situ rock properties.

A Geological-Geophysical Model of the Lens in the Junction Zone of the Chu Basin and the Kyrgyz Range (Northern Tien Shan) by the Results of Seismic Tomography and Magnetotelluric Sounding

Abstract —Along the submeridional seismic and magnetotelluric profiles, crossing the junction zone of the Kyrgyz Range and the Chu basin of the Northern Tien Shan, the models of density, Poisson’s ratio, elastic modulus, silica content, temperature, and porosity have been constructed. Based on the joint analysis of the constructed profiles of physicomechanical rock properties, a geological-geophysical lens model has been constructed. This model addresses the sources of geophysical anomalies (found at the northern border of the lens) and possible mechanisms of the lens formation.

Carbonate strength classification based on depositional textures and fossil content of the Lower Eocene Drunka Formation, Assiut Area, central Egypt

The present study reports petrographic and physico-mechanical analyses conducted on the lower Drunka Formation in the Assiut Area of Central Egypt. The study investigated the percentage of carbonate content and percentage of allochems “Ach” and their impact on the petrophysical features using correlation and multivariate regression analyses. This study analyzes the petrophysical characterization of Drunka Formation rocks and the effect of fossil content on them. The carbonate rock samples derived from the lower Drunka Formation were studied to evaluate the compressive strength , dry and saturated unit weight, porosity, and acoustic wave velocities. The petrographic examination of the rock samples was conducted to understand the facies characteristics, size and percentage of grains, matrix type and extent of diagenesis . Various microfacies associations were also detected within the examined samples, such as lime-mudstone, echinoidal bioclastic wackestones, nummulitic/miliolid wackestones, bioclastic peiodal packstone, echinoidal packstone and nummulitic grainstone . Petrophysical analyses displayed a wide range of porosity and dry bulk density values from 1.3 to 2.75% and 2.31–2.48 g/cm 3 , respectively. The wet bulk density and grain densities are between 2.33˗2.50 and 2.35˗ 2.57 g/cm 3 , respectively. The dry ultrasonic wave velocity “V p” was observed between 2926 and 5549 m/s, whereas the saturated ultrasonic wave velocity “V p “was estimated between 3067 and 5875 m/s. The Unconfined Compressive Strength (UCS) of the tested samples was 22 ≤ UCS ≤ 82 MPa while the slake durability index was recorded as 94.37 ≤ SDI ≤ 98.7%. The Brazilian test indices characterized the studied rock samples as highly porous rocks and showed the values of 1.47 ≤ Brazilian ≤ 5.13 MPa. Finally, for all tested facies, the Böhme test data have a minimum, maximum, and an average of 12.98, 25.95, and 19.04 cm 3 /50 cm 2, respectively. The study's findings showed that, except for the mineral grain scale, the physico-mechanical properties are highly dependent on the petrographic characteristics. The study also revealed that the Ach% and the rock's carbonate content significantly affect the rock's petrophysical and mechanical properties under investigation. The mechanical properties such as UCS, tensile and point load test. increase with increasing carbonate content and decreasing with increasing Ach% of the rock. This paper presents an extensive dataset of physical parameters of a carbonate formation in Egypt; many empirical relationships are presented for predicting mechanical properties. This provides site-specific predictive value; the relationships can be used for all carbonate rocks worldwide with broader international significance. • Classification of strength from texture is proposed based on fossil and carbonate content. • This study analyzes the petrophysical characterization of Drunka Formation rocks and the effect of fossil content on them. • This paper introduces a new strength classification of carbonate rocks based on allochems and carbonate content. • The depositional texture of carbonate rocks has a significant impact on variations of physico-mechanical properties of rocks. • Diagenesis has a remarkable effect on rock strength.

New approach for prediction of specific energy using sound levels produced during core drilling operations

ABSTRACT Specific energy (SE) is the energy required to excavate a unit volume of rock. It is a very important variable in the planning and designing of excavation projects, mining, and petroleum industry and depends on rock properties. This investigation reports about the prediction of SE, the effect of properties of rocks on SE, and the effect of operational variables on SE using sound levels created during the drilling process. Initially, SE was determined for all selected rock types and a correlation was developed between SE and physico-mechanical rock properties (PMRP) and operating variables. The developed prediction models were validated using determination coefficients (R2), the t-test, F-test, and performance predictions i.e. values account for (VAF), root mean square error (RMSE) and mean absolute percentage error (MAPE). For SE, the R2 values obtained a range from 75.58% to 78.76%, RMSE values obtained a range from 0.074411 to 0.578601, VAF values obtained a range from 72.826808 to 84.155813 and MAPE values obtained a range from 0.061218 to 2.321007 for selected rock samples and also, t and F values obtained below the tabulated values. Concerning SE’s relation to PMRP, it was observed that SE increased with increasing uniaxial compressive strength, Brazilian tensile strength, and dry density and decreased with increasing abrasivity. For PMRP, the R2 values obtained from 92.25%, 90.99%, 47.15%, 93.39%, corresponded to uniaxial compressive strength, Brazilian tensile strength, density, and abrasivity. Similarly, regarding SE’s relation with operational variables, it was observed that SE decreased with increasing drill bit diameters, penetration rates, and drill bit speed. The developed models can be served in the exploration and excavation projects for the prediction of specific energy.

Determining the relationship between shear wave velocity and physicomechanical properties of rocks

Thorough knowledge of physicomechanical properties of rocks is crucial during the primary and secondary stages of designing a rock engineering project. Laboratory examination of these properties requires high-quality rock specimens. However, preparing such high accuracy samples is a difficult, expensive, and time-consuming task, especially in weak and fractured rocks. Hence, indirect approaches seem an attractive research area for determining these properties. The main object of this study is to develop some empirical relations to determine different physical and mechanical properties of sedimentary and metamorphic rocks based on the shear wave velocity index. To do that, several schist, phyllite, and sandstone core samples were collected from the drilled boreholes in the Marivan Azad dam in western Iran. Then, the shear wave velocity and some physical and mechanical properties of rocks were measured in dry and saturated conditions. Subsequently, statistical analyses were conducted to develop shear wave velocity-based equations to determine different rock properties, including uniaxial compressive strength, modulus of elasticity, porosity, Poisson’s ratio, slake durability index, density, and water absorption. An equation with the maximum correlation coefficient was proposed as the optimum equation to determine each of the above rock properties. Finally, the results of the proposed empirical equations were compared with those of laboratory measurements. This comparison proved the proposed equations to have high accuracy for determining the physicomechanical properties of rocks and can be used in practical projects with similar geological conditions to save time and money.

Artificial neural network for prediction of rock properties using acoustic frequencies recorded during rock drilling operations

Determining properties of rocks in rock mechanics/engineering applications such as underground tunnelling, slope stability, foundations, dam design and rock blasting is often difficult due to the requirements of high quality of core rock samples and accurate test apparatus. Prediction of the geomechanical properties of rock material has been an area of interest for rock mechanics for several years now. Nowadays, soft computing methods are used as a powerful tool to estimate the rock properties, cost and duration of the project. This has led to a lack of necessity to develop a model to predict rock properties in the field of rock mechanics. ANN (artificial neural network) models were developed to predict geomechanical properties of the sedimentary rock types using dominant frequencies of an acoustic signal during rock drilling operations. A set of experimental drilling operations test conditions around 875 were used as input parameters including drill bit spindle speeds (rpm), drill bit penetration rates (mm/min), drill bit diameters (mm) and dominant frequencies of the acoustic signal (Hz). The response (output) was uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), density ( $$\rho $$ ) and abrasivity (%). The developed models were checked using various performance indices. The results from the analysis show that the suggested ANN model approach is efficient, fits the data and accurately reflects the experimental results. The ANN models predicted physico-mechanical rock properties through the dominant frequency of acoustic signals during rock drilling operations.

Characterization of the Petrographic and Physicomechanical Properties of Rocks from Otanm\xe4ki, Finland

Intact rock properties are important for mining and geotechnical engineering because they are important design parameters for tunnels, rock foundations, rock slopes, among others. Some of the properties are also used as input parameters in some rock mass classification systems. Therefore, as rock properties are site-specific, there is need to investigate rock properties at a site especially when such site is used for engineering purpose. This paper documents the petrographic and X-ray fluorescence analyses, and physical and mechanical tests conducted to estimate the physical and mechanical properties of the two rock types (i.e. gabbro and granite) selected from quarries at Otanmäki, Finland. Mineral composition, grain size and chemical composition, water content, porosity, Brazilian tensile strength, uniaxial compressive strength, Young’s modulus, and Poisson ratio of the rock types were determined. Both gabbro and granite samples have fine to medium grained texture. The results of laboratory experiments conducted show that rock properties investigated have low to high variability. Simple and multiple regression analyses were performed and useful predictive models for estimating Brazilian tensile strength from physical test results were developed and validated.

Effect of the rock properties on sawability of granite using diamond wire saw in natural stone quarries

Sawability of diamond wire saw is a cost-sensitive parameter in natural stone quarries that affects directly the production planning and equipment selection. The present study intended to investigate the effect of rock properties on sawability of diamond wire saw in granite quarries by considering the cutting rate and unit wear as the main sawability criteria. Hourly cutting rate of stone and unit wear of diamond impregnated beads of diamond wire saw were measured during the stone sawing process in 9 granite quarries. Moreover, physico-mechanical rock properties were determined in the laboratory. Statistical regression models were built to quantitatively analyze the effect of individual rock property on the cutting rate and unit wear. Further, the principal component analysis (PCA) and best subset regression with Bayesian information criterion (BIC) were performed in order to determine the combined effect of most influential rock properties on sawability. Valid for all tested granites, the experimental results indicated that the tensile strength, abrasivity, and brittleness are the most influential rock properties for the prediction of stone cutting rate, whereas compressive strength, elasticity, and abrasivity are dominant for prediction of unit wear of diamond beads.

CHANGES IN THE COMPOSITION AND PROPERTIES OF THE HOST ROCKS OF COAL DEPOSITS IN YAKUTIA UNDER THE INFLUENCE OF CRYOGENESIS

The results of laboratory tests carried out on rock samples of the Kharbalakhskoye coalfield located in Central Yakutia revealed significant secondary changes having taken place in the host rocks containing the coal. Evidently, under transformation processes, it is not only the composition of the rocks that had changed, but also the nature of structural bonds that have a great influence on their physical and mechanical properties. Thus, the ultimate strength values of coal-containing sandstone and siltstone samples under uniaxial compression vary from 20 to 30 MPa, while under uniaxial tension, the ultimate strength values range from 6 to 10 MPa. These relatively low numerical values pertaining to the physicomechanical properties of rocks, which are generally atypical for long-flame coal deposits, are almost 50% lower than those of analogous rocks hosting other coal deposits in Russia. It is considered that the mechanical strength properties of the rocks of the Kharbalakhskoye field are due to significant cryogenic processes. A comparative analysis of the properties of core samples obtained from boreholes drilled in 2019 with samples from a quarry obtained several decades ago reveals signs of transformation of rocks in the Kharbalakhskoye field due to phase transitions of freezing and thawing water.

Production and Environmental Monitoring at PAO Surgutneftegaz

This paper analyzes the performance of systems for removal of sludge from the drilling mud. It shows that the solid-phase particle-size distribution, which depends on the mineral composition and the physico-mechanical properties of rock, the drilling mud process parameters and the type of the rock cutter, as well as the drilling parameters affect the performance of vibrating screens, hydrocyclones, and centrifuges. The paper proposes upgrading the cleaning system by installing a second layer of fine-meshed sieve cassettes where hydrocyclones discharge their output. This improvement reduces the unproductive drilling time.

ОЦЕНКА ВАРИАНТОВ ОТРАБОТКИ ПРИБОРТОВЫХ И ПОДКАРЬЕРНЫХ ЗАПАСОВ РУДНИКА «ОЛЕНИЙ РУЧЕЙ»

Актуальность исследования обусловлена необходимостью отработки новых рудных тел, появившихся в ходе проведения опережающей эксплуатационной разведки. За проектными контурами рудников остаются запасы, которые необходимо доработать либо подземным, либо комбинированным способами. При технологии доработки прикарьерных запасов возникают наибольшие сложности, поскольку их отработка вызывает нарушение обеспечения устойчивости откосов борта карьера. Поэтому поиск, выбор и определение главных параметров системы разработки прикарьерных запасов при доработке месторождений, обеспечивающих эффективное и безопасное освоение запасов, представляет весьма актуальную задачу. Цель: рассмотреть возможные варианты отработки прибортовых и подкарьерных запасов с учетом залегания новых рудных тел апатит-нефелинового месторождения и соблюдением необходимых условий для заданного направления развития горных работ в границах горного отвода и произвести технико-экономическую оценку предложенных вариантов. Объект: крупное месторождение апатит нефелиновых руд «Олений ручей». Методы: горно-геологический анализ верхнего яруса месторождения апатит-нефелиновых руд «Олений ручей» и анализ существующих данных о физико-механических свойствах горных пород, слагающих массив рассматриваемого месторождения, анализ возможных схем развития горных работ при отработке прикарьерных запасов с оценкой возможности внутреннего отвалообразования при доработке карьера. На примере разработки месторождения апатит-нефелиновых руд «Олений ручей» авторами рассмотрены возможные варианты отработки и вскрытия прибортовых и подкарьерных запасов верхнего яруса месторождения с соблюдением условий развития горных работ в границах горного отвода. Предложено оптимальное развитие горных работ по варианту, предусматривающему минимальный коэффициент вскрыши.

Effects of high-temperature heating and cryogenic quenching on the physico-mechanical properties of limestone

This paper is designed to investigate the influence of high-temperature heating and cryogenic quenching using liquid nitrogen (LIN) cooling on the physico-mechanical properties of limestone such as compressive strength, tensile strength, ultrasonic pulse velocity (UPV) and morphological characterization. The main aim is to provide a better understanding on influence of the temperature shock including high temperature pre-treatments and combined process with heating followed by LIN quenching on the physico-mechanical properties of rock. The samples were subjected to different thermal treatment using high-temperature of 100 °C, 200 °C, 400 °C and 600 °C for 4 h. In addition, the combined process of heating at 600 °C for 4 h and LIN quenching for 15 min, 30 min, 45 min and 60 min has also been explored. The obtained results indicate that pre-treatments in limestone depict decreasing trend in strength values. Limestone samples show 62% drop in uniaxial compressive strength (UCS) and 84% drop in Brazilian tensile strength (BTS) for 600 °C pre-treatment for 4 h, whereas the decrease in 70% of UCS and 89% of BTS are also observed for the combined process with 60 min of LIN quenching. The influence of pre-treatment on UPV and microstructure of rock has been investigated in detail. Due to thermal stress, very low UPV has been obtained for the pre-treated samples compared to untreated. SEM analysis has been carried out to understand the fracture morphology for both untreated and treated rock samples.

Experimental Investigation of Mechanical Behavior of Sandstone with Different Moisture Contents Using the Acoustic Emission Technique

The moisture content is a critical factor tightly related to rock deformation and its failure process since it leads to a significant change in the physicomechanical properties of rock during the underground engineering construction. As a result, engineering construction accidents take place frequently. To figure out the influence of the moisture content on the physicomechanical properties of water‐bearing rock and then effectively avoid engineering accidents, multiple tests including the uniaxial compression test, Brazilian splitting test, and the acoustic emission (AE) test were carried out in this study. The experimental results showed that the water absorption rate of the sandstone gradually stabilizes after 5 h, and its uniaxial compressive strength, tensile strength, and elastic modulus all decline with the increase of the moisture content. Compared to the dry state of the sample, the reduction amplitudes of the elastic modulus, compressive strength, and tensile strength of water‐saturated rock samples can reach up to 27.3%, 35.2%, and 38.1%, respectively. It indicates that the tensile strength is more sensitive to the softening effect of the moisture. Through the AE test, it can be found that the internal state of water‐saturated rock samples is greatly changed; the compressive strength of rock samples drops, so the rock can be damaged after absorbing less energy. Thus, moisture shows a certain softening effect on rock. The research results are expected to provide a basis for underground engineering construction and rock fracture and failure.

Influence of paleodislocation intensity and modern movements on the stressed state of massif

To study the nature of the forces determining the stress state of the massif, the results of experimental studies of determining numerical values and spatial orientation of the main components of the active stress field using the local hydraulic fracturing method in coal mines of Central Region of Donbas are compared with maps characterizing the intensity of the distribution of paleo-and modern tectonic processes in the area of Donbas. Statistical relationships between indicators characterizing the stress state and the physicomechanical properties of rock are established. The results of performed studies show that the stress fields measured under the conditions of the mines of the Central Region of Donbas are mainly due to modern movements, but the paleological disturbances of tectonic blocks with disjunctive dislocations have a significant effect on the change in the stress state of the massif.