共查询到20条相似文献，搜索用时 15 毫秒
1.
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
2.
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
3.
《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
4.
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
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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.
孕镶金刚石钻头通过钻头胎体的持续磨损实现金刚石的自锐和高效破岩。因此,研究金刚石钻头磨损的影响因素及其影响程度和影响机理,对孕镶金刚石钻头的设计和使用非常重要。本次研究探讨了岩石物理力学性质、钻头胎体性能和钻进工艺参数等因素对孕镶金刚石钻头磨损过程和磨损机理的影响。分析表明,对钻头磨损最为显著的影响因素是岩石中的硬质颗粒导致的磨粒磨损,其次是钻头胎体与岩粉之间的粘着磨损,以及冲洗液中岩粉颗粒导致的冲蚀磨损。在此基础上,以不同硬度的钻头胎体摩擦磨损试验结果为例,探讨了钻头胎体性能及其内部硬质点对钻头磨损的影响机理。该研究成果可为科学设计与合理使用孕镶金刚石钻头提供依据。 相似文献
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9.
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
10.
Study of Dominant Factors Affecting Cerchar Abrasivity Index 总被引：2，自引：1，他引：1
Jamal Rostami Amireza Ghasemi Ehsan Alavi Gharahbagh Cihan Dogruoz Filip Dahl 《Rock Mechanics and Rock Engineering》2014,47(5):1905-1919
The Cerchar abrasion index is commonly used to represent rock abrasion for estimation of bit life and wear in various mining and tunneling applications. Although the test is simple and fast, there are some discrepancies in the test results related to the equipment used, condition of the rock surface, operator skills, and procedures used in conducting and measuring the wear surface. This paper focuses on the background of the test and examines the influence of various parameters on Cerchar testing including pin hardness, surface condition of specimens, petrographical and geomechanical properties, test speed, applied load, and method of measuring wear surface. Results of Cerchar tests on a set of rock specimens performed at different laboratories are presented to examine repeatability of the tests. In addition, the preliminary results of testing with a new device as a potential alternative testing system for rock abrasivity measurement are discussed. 相似文献
11.
Abrasivity Assessment of Granitic Building Stones in Relation to Diamond Tool Wear Rate Using Mineralogy-Based Rock Hardness Indexes 总被引：1，自引：1，他引：0
Nurdan Güneş Yılmaz 《Rock Mechanics and Rock Engineering》2011,44(6):725-733
The objective of the present study was to determine the abrasive wear potential of granites in circular sawing using some
mineralogy-based rock hardness indexes. A literature study indicated that little or no attention has been given to assessing
this kind of relationship in the field of stone processing. To accomplish this objective, sawing experiments were performed
on nine different granites used widely as building and decorative stone materials. The measured sawblade-specific wear rates
were correlated with three different rock hardness indexes attained by combining the percentage content of hard mineral constituents
with their known hardness values. Statistical analysis of the experimental data revealed that rock hardness indexes that are
based on both Vickers hardness number and Rosiwal hardness could be accepted as reliable indicators of granite abrasivity.
These two indexes were also found to correlate well with the average power drawn during the process. However, the rock abrasivity
index based on Mohs relative scratch hardness did not show statistically significant correlations with sawblade wear rate
and power drawn. Although quartz percentage content is regarded as an important abrasivity parameter by practitioners, the
observations made here indicate that consideration of quartz percentage content alone is not sufficient to describe the abrasive
potential of granites, and thus incorporation of other hard mineral constituents could be more suitable. 相似文献
12.
A model of tunnel boring machine performance 总被引：2，自引：0，他引：2
G. Wijk 《Geotechnical and Geological Engineering》1992,10(1):19-40
13.
Continuous Monitoring of Pin Tip Wear and Penetration into Rock Surface Using a New Cerchar Abrasivity Testing Device 总被引：1，自引：0，他引：1
Mohammad-Taghi Hamzaban Hossein Memarian Jamal Rostami 《Rock Mechanics and Rock Engineering》2014,47(2):689-701
Evaluation of rock abrasivity is important when utilizing mechanized excavation in various mining and civil projects in hard rock. This is due to the need for proper selection of the rock cutting tools, estimation of the tool wear, machine downtime for cutter change, and costs. The Cerchar Abrasion Index (CAI) test is one of the simplest and most widely used methods for evaluating rock abrasivity. In this study, a new device for the determination of frictional forces and depth of pin penetration into the rock surface during a Cerchar test is discussed. The measured parameters were used to develop an analytical model for calculation of the size of the wear flat (and hence a continuous measure of CAI as the pin moves over the sample) and pin tip penetration into the rock during the test. Based on this model, continuous curves of CAI changes and pin tip penetration into the rock were plotted. Results of the model were used for introduction of a new parameter describing rock–pin interaction and classification of rock abrasion. 相似文献
14.
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
15.
Nurdan Günes Yılmaz 《Rock Mechanics and Rock Engineering》2013,46(1):95-106
The Equotip hardness tester (EHT) is a portable and non-destructive instrument used mainly for the dynamic rebound hardness testing of metals. Although various versions of the ‘single impacts’ and ‘repeated impacts’ testing procedures have been employed by different authors for different applications, it is not yet known whether a particular testing procedure is more relevant for a specific application in rock engineering. To be able to contribute to the subject, the present study was carried out to determine the suitability of different rebound testing procedures with this instrument for uniaxial compressive strength (UCS) estimations of some selected carbonate rocks. To achieve this goal, as well as four different existing rebound testing procedures, a newly proposed testing methodology involving the parameter hybrid dynamic hardness (HDH) was also employed. The statistical analyses performed on the experimental data, on the whole, showed that the test procedures which are based on single impacts test procedures outperformed the repeated impacts test procedures in terms of UCS prediction accuracy. The prediction capability of the newly introduced testing methodology was found to be superior to those of other procedures considered in this work, suggesting that it could be an efficient tool in practice for preliminary estimates of rock strength. The statistical analyses also indicated that, in practical applications of the EHT using different test procedures, it may be possible to predict the UCS more accurately when apparent density data is available. For the range of specimen sizes considered, no clear evidence of size effect was observed in the mean rebound values. The argument raised by some other authors that the EHT might not be a convenient instrument for the dynamic rebound hardness determination of relatively high-porosity rocks was not confirmed in this study. 相似文献
16.
This study aims to establish new correlations to assess uniaxial compressive strength (UCS) of northern Algeria sedimentary rocks. This estimation is based on the measurements of density, porosity, and Schmidt hammer hardness. To achieve this goal, a geological and geotechnical characterization campaign was conducted on 19 types of sandstone and carbonate rocks which have been collected from different geological areas of the Maghrebides chain. Petrographic analyses were conducted to identify the geological characteristics of each kind of rock. Subsequently, physico-mechanical tests (i.e., density, porosity, hardness, and uniaxial compressive strength) were carried out for all the sampled rocks. The results were then used to develop correlations between UCS values and the other parameter values determined. Finally, the UCS predictive equations which have the best predictive powers (coefficient of determination R 2 of 0.75 to 0.94) were discussed taking into account the geological specificities of the rocks, and then compared to similar studies developed by other authors in different areas of the world. 相似文献
17.
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
18.
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
19.
Akbar Balani Hamid Chakeri Ghodrat Barzegari Yilmaz Ozcelik 《Geotechnical and Geological Engineering》2017,35(6):2747-2762
The Cerchar test is one of the appropriate and routine tests for determining the rock abrasion; but as for the costs and pin wear measurement errors in laboratory procedures and lack of access to laboratory equipment, using of numerical modeling can lead to use of greater number of samples required during the course of mechanized excavation and reduce the costs and errors in the laboratory test. In this study, the Cerchar abrasivity test was modeled using PFC3D (Particle Flow Code in 3 Dimensions) software. In order to verify the simulation results, Cerchar laboratory test results obtained by Rostami (Rock Mech Rock Eng 47(5):1905–1919, 2014) were compared with the numerical modeling results. In modeling studies, the effects of some parameters such as apply load, test speed, pin hardness and scratching distance on pin wear were investigated. As a conclusion of the study, good agreement between modeling and experimental results was obtained for a given condition. As in the experiment with various loads in both laboratory tests and modeling, with increasing applied load the Cerchar abrasivity index also increased in the experiment with Rockwell hardness HRC (An abbreviation for Rockwell Hardness measured on the C scale. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload, that on the C scale use from a indenter with 120° cone and 150 kgf load) 42. 相似文献
20.
金刚石钻头是勘探工作中的常见破岩工具,但金刚石热稳定性较差,在钻进过程中会不断产生热量,干旱缺水条件下钻头自冷却对钻进效率的提高具有非常重要的意义。为降低干钻条件下钻头胎体与岩石界面间的摩擦因数从而减少钻进过程中金刚石的热损伤,在热压Fe基金刚石钻头胎体中添加二硫化钼(MoS2),研究MoS2含量对Fe基钻头胎体相对密度、洛氏硬度、抗弯强度以及与白刚玉砂轮干磨时的磨损量和摩擦因数的影响,并用扫描电子显微镜(SEM)和能谱仪(EDS)等测试仪器分析了抗弯强度和摩擦磨损试验后的试样断口和表面的形貌及物相成分。试验结果表明,在试验范围内,Fe基胎体相对密度与MoS2含量关系不大,但是与未添加MoS2的Fe基胎体相比,其相对密度提高了约2.5%,达98%以上。Fe基胎体洛氏硬度随着MoS2含量的增加先增大后减小,在MoS2体积分数为8%时胎体硬度最大,洛氏硬度HRB值达101.3。Fe基胎体抗弯强度随着MoS2含量的增加先增大后减小,在MoS... 相似文献