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1.
Prediction of specific energy of carbonate rock in industrial stones cutting process 总被引：2，自引：2，他引：0
Specific energy (SE) measurements of circular saws were conducted on 12 different carbonate rocks. Rock samples were collected from the factories for laboratory tests. Bulk density, apparent porosity, uniaxial compressive strength, Brazilian tensile strength, flexural strength, Schmidt rebound hardness, Shore hardness, point load strength index, Los Angeles abrasion values, and P-wave velocity values were determined in the laboratory. SE and rock properties were evaluated using simple regression analysis and empirical equations were developed. The equations were verified by statistical tests. Regression analysis showed that high correlations exist between SE and uniaxial compressive strength, Shore and Schmidt hardness, bulk density, apparent porosity, and flexural strength. It was found that the SE value of rocks in cutting process was highest for those rocks having the high density, compressive strength, flexural strength, Schmidt and Shore hardness, point load strength index, and P-wave velocity values. 相似文献
2.
A rippability classification system for marls in lignite mines 总被引：1，自引：0，他引：1
3.
Abdolazim Azimian 《Acta Geotechnica》2017,12(2):321-333
Uniaxial compressive strength (UCS) of an intact rock is an important geotechnical parameter for engineering applications. Using standard laboratory tests to determine UCS is a difficult, expensive and time-consuming task. The main purpose of this study is to develop a general model for predicting UCS of limestone samples and to investigate the relationships among UCS, Schmidt hammer rebound and P-wave velocity (V P). For this reason, some samples of limestone rocks were collected from the southwestern Iran. In order to evaluate a correlation, the measured and predicted values were examined utilizing simple and multivariate regression techniques. In order to check the performance of the proposed equation, coefficient of determination (R 2), root-mean-square error, mean absolute percentage error, variance accounts for (VAF %), Akaike Information Criterion and performance index were determined. The results showed that the proposed equation by multivariate regression could be applied effectively to predict UCS from its combinations, i.e., ultrasonic pulse velocity and Schmidt hammer hardness. The results also showed that considering high prediction performance of the models developed, they can be used to perform preliminary stages of rock engineering assessments. It was evident that such prediction studies not only provide some practical tools but also contribute to better understanding of the main controlling index parameters of UCS of rocks. 相似文献
4.
The Schmidt hammer in rock material characterization 总被引：2，自引：0，他引：2
The Schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material. However, a number of issues such as hammer type, normalization of rebound values, specimen dimensions, surface smoothness, weathering and moisture content, and testing, data reduction and analysis procedures continue to influence the consistency and reliability of the Schmidt hammer test results. This paper presents: a) a critical review of these basic issues; and b) the results of tests conducted on granitic rocks of various weathering grades in the light of the conclusions of this review. It was found that a very good correlation exists between L and N hammer rebound values and that both hammers are fairly sensitive to the physical properties, particularly to dry density though less so to effective and total porosities. The N hammer, producing a lesser scatter in the data, proved to be more efficient than the L hammer in predicting uniaxial compressive strength and Young's modulus. The exponential form of the correlation curves was found to reflect microstructural changes during the course of weathering and the differences in the probing scales or mechanisms in the means of measuring these mechanical properties, and could be generalized to other crystalline igneous rocks. The possibility of predicting weathering grades from rebound values was also explored. The changes in the rebound values during multiple impacts at a given point produced a better indication of the weathering grade than a single impact value. It was concluded that increasing the impact energy and plunger tip diameter should significantly reduce the scatter in coarse-grained weathered rocks and hence improve the reliability of the Schmidt hammer as a rock material characterization tool. 相似文献
5.
Summary A weathering classification for granitic rock materials from southeastern Brazil was framed based on core characteristics.
The classification was substantiated by a detailed petrographic study. Indirect assessment of weathering grades by density,
ultrasonic and Schmidt hammer index tests was performed. Rebound values due to Schmidt hammer multiple impacts at one representative
point were more efficient in predicting weathering grades than averaged single impact rebound values, P-wave velocities and
densities.
Uniaxial compression tests revealed that a large range of uniaxial compressive strength (214–153 MPa) exists in Grade I category
where weathering does not seem to have played any role. It was concluded that variability in occurrences of quartz intragranular
cracks and in biotite percentage, distribution and orientation might have played a key role in accelerating or decelerating
the failure processes of the Grade I specimens. Deterioration of uniaxial compressive strength and elastic modulus and increase
in Poisson’s ratio with increasing weathering intensity could be attributed to alteration of minerals, disruption of rock
skeleton and microcrack augmentation. A crude relation between failure modes and weathering grades also emerged.
Correspondence: Prof. T. B. Celestino, Universidade de S?o Paulo, S?o Carlos, Brazil 相似文献
6.
This study aims to express the relationships between Schmidt rebound number (N) with unconfined compressive strength (UCS) and Young's modulus (Et) of the gypsum by empirical equations. As known, the Schmidt hammer has been used worldwide as an index test for a quick rock strength and deformability characterisation due to its rapidity and easiness in execution, simplicity, portability, low cost and nondestructiveness. In this study, gypsum samples have been collected from various locations in the Miocene-aged gypsum of Sivas Basin and tested. The tests include the determination of Schmidt hammer rebound number (N), tangent Young's modulus (Et) and unconfined compressive strength. Finally, obtained parameters were correlated and regression equations were established among Schmidt hammer rebound hardness, tangent Young's modulus and unconfined compressive strength, presenting high coefficients of correlation. It appears that there is a possibility of estimating unconfined compressive strength and Young's modulus of gypsum, from their Schmidt hammer rebound number by using the proposed empirical relationships of UCS=exp(0.818+0.059N) and Et=exp(1.146+0.054N). However, the equations must be used only for the gypsum with an acceptable accuracy, especially at the preliminary stage of designing a structure. Finally, by using the obtained Schmidt hammer rebound number from this study, unconfined compressive strength was calculated and compared with the calculated value from different empirical equations proposed by different authors. It can be said that it is impossible to obtain only one relation for all types of the rocks. 相似文献
7.
Weathering processes cause important changes in the engineering properties of rocks. In this study, dunites in the Bursa region
in western Turkey were investigated and the changes in engineering properties due to weathering were evaluated. The studies
were initiated with field observations including measurement of the characteristics of discontinuities such as spacing, aperture,
fill material, roughness, and Schmidt hammer rebound value. Subsequently, laboratory studies were conducted in two stages.
The first stage comprised mineralogical, petrographic, and chemical analyses. The second stage included physicomechanical
tests to determine specific gravity, unit weights, water absorption, effective porosity, uniaxial compressive strength, P-wave
velocity, and slake-durability index. According to these evaluations, the changes in engineering properties were determined
to be mostly related to serpentinization at every stage of weathering. The most suitable parameters for characterizing the
degree of weathering of the studied dunites are loss-on-ignition values, specific gravity, unit weight, water absorption,
and effective porosity. 相似文献
8.
Preparing high-quality samples, which can fulfill testing standards, from weak and block-in-matrix conglomerate for laboratory tests, is a big challenge in engineering projects. Hence, using indirect methods seems to be indispensable for determination uniaxial compressive strength (UCS). The main objective of this study is to estimate the relation between sonic velocity (Vp), Schmidt hammer rebound number (SCH) and UCS. For this reason, some samples of weak conglomeratic rock were collected from two different sites of dam in Iran (Bakhtiari and Hezardareh Formations). In order to evaluate the correlation, the measured and predicted values utilizing simple and multivariate regression techniques were examined. To control the performance of the proposed equation, root mean square error (RMSE) and value accounts for (VAF%) were determined. The VAF% and RMSE indices were computed as 94.34 and 1.56 for the relation between Vp and UCS from simple regression model. These were 94.39 and 1.6 between SCH and UCS, while these were 97.24 and 1.34 for uniaxial compressive strengths obtained from multivariate regression model. 相似文献
9.
《Geomechanics and Geoengineering》2013,8(1):53-61
In many rock engineering applications such as foundations, slopes and tunnels, the intact rock properties are not actually determined by laboratory tests, due to the requirements of high quality core samples and sophisticated test equipments. Thus, predicting the rock properties by using empirical equations has been an attractive research topic relating to rock engineering practice for many years. Soft computing techniques are now being used as alternative statistical tools. In this study, artificial neural network models were developed to predict the rock properties of the intact rock, by using sound level produced during rock drilling. A database of 832 datasets, including drill bit diameter, drill bit speed, penetration rate of the drill bit and equivalent sound level (Leq) produced during drilling for input parameters, and uniaxial compressive strength (UCS), Schmidt rebound number (SRN), dry density (ρ), P-wave velocity (Vp), tensile strength (TS), modulus of elasticity (E) and percentage porosity (n) of intact rock for output, was established. The constructed models were checked using various prediction performance indices. Goodness of the fit measures revealed that recommended ANN model fitted the data as accurately as experimental results, indicating the usefulness of artificial neural networks in predicting rock properties. 相似文献
10.
Analysis of Impact Hammer Rebound to Estimate Rock Drillability 总被引：6，自引：0，他引：6
Summary ?In this paper, the piston rebound common to both the Schmidt Impact Hammer and down-hole hammer drills has been analyzed
and calculated by means of stress wave theory and the energy conservation law. A quantitative relationship between the amount
of rebound of the piston and the impact resistance index, or hardness of the rock, has been established. Those analytical
results will not only be of benefit in acquiring a deep understanding of the usable range and condition of the Schmidt Impact
Hammer, but also provide a definite answer to the feasibility of using the hammer rebound in drills with down-hole hammer
tool to carry out a real time measurement of the nature of the formation under the bit. 相似文献
11.
Engineering properties of rocks vary as they are heterogeneous materials by nature because of mineralogical composition, texture, porosity, and alteration, etc. This study focuses on the investigation of the relationship between internal structure and engineering parameters of basalt samples by digitizing the textural properties. Thin sections studies of basalts were made into three groups: aphanitic, amygdaloidal, and vesicular on the basis of texture. Further, the textural properties were digitized in thin sections and the texture coefficient (TC) of each group was calculated. Uniaxial compressive strength, dry unit weight, point load strength index, Schmidt hammer rebound, and P-wave velocity of the samples were determined in the laboratory. Simple regression analyses were performed using the laboratory results incorporating first TC and engineering parameters and the second phase of the analysis focused on the relationship between uniaxial compressive strength and the rest of the parameters of samples with different texture coefficients. The highest texture coefficient was found to be 0.50 in aphanitic basalts while vesicular basalts have the lowest TC of 0.37. As the TC increases, rock strength increases. Strong-very strong correlations between uniaxial compressive strength and the rest of the engineering parameters of aphanitic and amygdaloidal-basalts with a TC of 0.50 and 0.45 are in agreement with the findings in the literature while there are no meaningful correlations between uniaxial strength and the aforementioned parameters except dry unit weight in vesicular basalts. These results indicate that the presence of empty pores in vesicular basalts reduced the uniaxial compressive strength and TC by increasing the heterogeneity. 相似文献
12.
Amin Jamshidi Mohammad Reza Nikudel Mashallah Khamehchiyan Reza Zarei Sahamieh Yasin Abdi 《Arabian Journal of Geosciences》2016,9(10):568
As known, P-wave velocity and Schmidt hardness are non-destructive tests, which have been used for many years in geological, geotechnical, and civil engineering as an index tests for a quick assessment of rocks mechanical properties due to its rapidity and easiness, and non-destructiveness. The purpose of this study is to investigate the correlation between P-wave velocity and Schmidt hardness with some of mechanical properties of travertine building stones by empirical equations. Moreover, we have compared the accuracy of P-wave velocity and Schmidt hardness to estimate the mechanical properties of rocks. For this purpose, 15 types of travertine have been collected from various quarries of Iran and tested. The tests include the determination of P-wave velocity and Schmidt hardness, and mechanical properties include the unconfined compressive strength, Brazilian tensile strength, and point load strength. Using data analysis, empirical equations have been developed for estimating the mechanical properties from P-wave velocity and Schmidt hardness. To check the validity of the empirical equations, a t test was performed, which confirmed the validity of the proposed empirical equations. Moreover, the results show that P-wave velocity appears to be more reliable than the Schmidt hardness for estimating the mechanical properties. Consequently, we propose empirical equations avoiding from cumbersome and time consuming tests for determining the mechanical properties of rocks. 相似文献
13.
Fuzzy and Multiple Regression Modelling for Evaluation of Intact Rock Strength Based on Point Load, Schmidt Hammer and Sonic Velocity 总被引：4，自引：0，他引：4
Summary. Uniaxial Compressive Strength (UCS), considered to be one of the most useful rock properties for mining and civil engineering
applications, has been estimated from some index test results by fuzzy and multiple regression modelling. Laboratory investigations
including Uniaxial Compressive Strength (UCS), Point Load Index test (PL), Schmidt Hammer Hardness test (SHR) and Sonic velocity
(Vp) test have been carried out on nine different rock types yielding to 305 tested specimens in total. Average values along
with the standard deviations (Stdev) as well as Coefficients of variation (CoV) have been calculated for each rock type. Having
constructed the Mamdani Fuzzy algorithm, UCS of intact rock samples was then predicted using a data driven fuzzy model. The
predicted values derived from fuzzy model were compared with multi-linear statistical model. Comparison proved that the best
model predictions have been achieved by fuzzy modelling in contrast to multi-linear statistical modelling. As a result, the
developed fuzzy model based on point load, Schmidt hammer and sonic velocity can be used as a tool to predict UCS of intact
rocks. 相似文献
14.
An Empirical Correlation of Index Geomechanical Parameters with the Compressional Wave Velocity 总被引：2，自引：0，他引：2
The geomechanical strength of rockmass plays a key role in planning and design of mining and civil construction projects.
Determination of geomechanical properties in the field as well as laboratory is time consuming, tedious and a costly affair.
In this study, density, slake durability index, uniaxial compressive strength (UCS) and P-wave velocity tests were conducted
on four igneous, six sedimentary and three metamorphic rock varieties. These properties are crucial and used extensively in
geotechnical engineering to understand the stability of the structures. The main aim of this study is to determine the various
mechanical properties of 13 different rock types in the laboratory and establish a possible and acceptable correlation with
P-wave velocity which can be determined in the field as well as laboratory with ease and accuracy. Empirical equations were
developed to calculate the density, slake durability index and UCS from P-wave velocities. Strong correlations among P-wave
velocity with the physical properties of different rock were established. The relations mainly follow a linear trend. Student’s
‘t’ test and ‘F’ test were performed to ensure proper analysis and validation of the proposed correlations. These correlations can save time
and reduce cost during design and planning process as they represent a reliable engineering tool. 相似文献
15.
The uniaxial compressive strength (UCS) of rocks is a critical parameter required for most geotechnical projects. However, it is not always possible for direct determination of the parameter. Since determination of such a parameter in the lab is not always cost and time effective, the aim of this study is to assess and estimate the general correlation trend between the UCS and indirect tests or indexes used to estimate the value of UCS for some granitoid rocks in KwaZulu-Natal. These tests include the point load index test, Schmidt hammer rebound, P-wave velocity (Vp) and Brazilian tensile strength (σt). Furthermore, it aims to assess the reliability of empirical equations developed towards estimating the value of UCS and propose useful empirical equations to estimate the value of UCS for granitoid rocks. According to the current study, the variations in mineralogy, as well as the textural characteristics of granitoid rocks play an important role in influencing the strength of the rock. Simple regression analyses exhibit good results, with all regression coefficients R2 being greater than 0.80, the highest R2 of 0.92 being obtained from UCS versus σt. Comparison of equations produced in the current study as well as empirical equations derived by several researchers serves as a validation. Also illustrate that the reliability of such empirical equations are dependent on the rock type as well as the type of index tests employed, where variation in rock type and index tests produces different values of UCS. These equations provide a practical tool for estimating the value of UCS, and also gives further insight into the controlling factors of the strength of the granitoid rocks, where the strength of a rock is a multidimensional parameter. 相似文献
16.
O. Yaralı 《Geotechnical and Geological Engineering》2017,35(4):1605-1614
This paper examines the relationships between Cerchar hardness index (CHI) and some mechanical properties of coal measure rocks in Zonguldak Hard Coal Basin. Some index properties (Cerchar hardness index, Shore scleroscope hardness, in situ Schmidt rebound hardness and point load strength) and strength (uniaxial compressive strength and Brazilian tensile strength) properties of 29 sedimentary rock samples are determined. Then, relationships between (CHI) and strength as well as and some other index values are evaluated using statistical methods. Linear relationships are found between CHI and uniaxial compressive strength, Schmidt rebound hardness. Power relationships are determined between CHI and Shore scleroscope hardness, diametral point load strength, point load strength anisotropy index. Besides, CHI tests are performed by means of bits having tip angles of 99° and 125° and excellent linear relationships are identified between them. 相似文献
17.
The process of drilling, in general, always produces sound. Though sound is used as a diagnostic tool in mechanical industry, its application in predicting rock property is not much explored. In this study, an attempt has been made to estimate rock properties such as uniaxial compressive strength, Schmidt rebound number and Young's modulus using sound level produced during rotary drilling. For this purpose, a computer numerical controlled vertical milling centre was used for drilling holes with drill bit diameters ranging from 6 to 20 mm with a shank length of 40 mm. Fourteen different rock types were tested. The study was carried out to develop the empirical relations using multiple regression analysis between sound level produced during drilling and rock properties considering the effects of drill bit diameter, drill bit speed and drill bit penetration rate. The F-test was used to check the validity of the developed models. The measured rock property values and the values calculated from the developed regression model are fairly close, indicating that the developed models could be efficiently used with acceptable accuracy in prediction of rock properties. 相似文献
18.
Performance Prediction of Large-Diameter Circular Saws Based on Surface Hardness Tests for Mugla (Turkey) Marbles 总被引：1，自引：0，他引：1
Avni Güney 《Rock Mechanics and Rock Engineering》2011,44(3):357-366
Surface hardness tests such as Shore hardness (SH) and Schmidt hammer rebound hardness (SR) may provide a quick and inexpensive
measure of rock hardness, which may be widely used for estimating the mechanical properties of rock material such as strength,
sawability, drillability and cuttability. In the marble industry, circular sawing with diamond sawblades constitutes a major
cost in the processing. Therefore, several models based on the relations between hourly slab production (P
hs), rock surface hardness (SH and SR) and mineral grain size (S
cr) were developed using the data obtained from field and laboratory measurements on five different marbles quarried in the
Mugla Province of Turkey. The models which include surface hardness and crystal size may as well be used for the prediction
of sawability (hourly slab production) of carbonate rocks using large-diameter circular saws. 相似文献
19.
The Cerchar abrasivity index (CAI) is one of the most widely known index method for identification of rock abrasivity. It is a simple and fast testing method providing reliable information on rock abrasiveness. In this study, the relationships between the CAI and some rock properties such as uniaxial compressive strength (UCS), point load strength, Brazilian tensile strength and Schmidt rebound hardness, and equivalent quartz content (EQC) are examined. The relationships between the CAI and drill bit lifetime is also investigated and the type of drill bit wear observed is mentioned. Additionally, the CAI is modeled using simple and multiple linear regression analysis based on the rock properties. Drill bit lifetime is also modeled based on the CAI. The results show that the CAI increases with the increase of the UCS, point load strength, Brazilian tensile strength, L-type and N-type Schmidt rebound hardness, and the EQC. It is concluded that the higher and the lower bit lifetime are obtained for marl and andesitic-basaltic formation, respectively. Moreover, flushing holes, inserted button, button removal, and failures of button on the bits are determined as the type of drill bit wear. The modeling results show that the models based on the UCS and the EQC give the better forecasting performances for the CAI. 相似文献
