Performance of roadheaders in low strength pyroclastic rocks, a case study of cold storage caverns in Cappadocia

Roadheaders are one of the mechanical excavators widely used in mine roadway excavation or tunneling projects. Therefore, researchers have usually investigated the performance of roadheaders only for these working areas. However, roadheaders can be also used in excavations of the other underground spaces which can be designed as cold storages, hotels, restaurants etc. In Cappadocia region, cold storage caverns (CSC) are excavated also by roadheaders and CSCs are generally constructed in tuff formations that are very soft, homogeneous, and can be carved out easily. The use of roadheaders for the excavation of CSCs may show some different characteristics in mining and tunneling projects. For example, the excavated formations are generally accepted as massive and since the drainage problem, water is not used during the excavations of CSCs. For such reasons, the performance of a roadheader may differ from the estimated performance calculated in the previous models. In this study, field performance of roadheaders were analyzed in eight different CSCs excavated in low strength pyroclastic rocks, in Cappadocia region. The excavation performance and cutter consumptions of the roadheaders were recorded in detail and the instantaneous cutting rates (ICRs) of the machines were determined. The Cerchar abrasivity tests and physico-mechanical tests were carried out on the core samples collected from the project areas. Relationships between field ICRs and results of physico-mechanical tests were analyzed. Based on the uniaxial compressive strength (UCS), a new site specific model for predicting roadheader performance was proposed for low-strength rocks with up to 10 MPa UCS. The ICRs of the roadheaders were calculated using some previously developed empirical models and compared with the field performance of the roadheaders and the results of the newly developed model. Similarly, a new model based on the Cerchar abrasivity index (CAI) for predicting cutter consumption rate of roadheaders was proposed to excavate low-strength tuffs. The amount of cutter consumption was also calculated using some previous models for each CSC project and compared with the field data. © 2019 Elsevier LtdThis study has been supported by the Scientific Research Project Unit of Niğde Omer Halisdemir University ( FEB2016/27-BAGEP ) and the Scientific and Technological Research Council of Turkey ( TUBITAK 217M171 ). The author greatly appreciates the HOYUK Construction Company for giving permission in the CSC projects and KEMPAR Company for their supports

Evaluation of the physico-mechanical properties of plutonic rocks based on texture coefficient

Understanding rock properties is of vital importance in mining and civil engineering. Rock properties are generally determined through laboratory tests, which require a large number of uniformly shaped samples and technicians who use indirect methods to determine rock properties. The texture coefficient (TC), which represents various textural parameters including the size, shape, orientation, and relative proportions of grains and the matrix, is an efficient means for indirectly evaluating the mechanical behaviour of rocks. In this study, 12 different rocks (ten granites, one diorite, and one gabbro) were collected and their engineering properties. including specific gravity, porosity, P-and S-wave velocities, Schmidt rebound hardness, uniaxial compressive strength, and elasticity modulus, were investigated. Relationships between TC and these measured properties were assessed. Statistically significant (at the 95% confidence level) correlations were found between the TC and compressive strength, elasticity modulus, sound velocity (both compression and shear waves for dry and saturated samples), but no significant correlation was found with Schmidt rebound hardness. The results suggest that it is possible to use the relationships between TC and the mechanical properties of rocks in rock classification. © The Southern African Institute of Mining and Metallurgy

A correlative study on textural properties and crushability of rocks

Rock texture is a term representing the mineral grains, grain sizes, and matrices of rocks. Crushability properties of rocks are very important parameters on an industrial scale and they can be determined by different methods. This study investigated the effects of textural properties of rocks on their crushability. For this purpose, some physical and mechanical tests were carried out on 12 different rock samples, which were divided into igneous, metamorphic, and sedimentary rock groups. All rock samples were crushed by using jaw and roll crushers, and crushability indices (CI) and particle sizes (d50, d80) were determined for all rock samples. The textural properties of rocks were defined by using the texture coefficient (TC) approach on thin section images. The test results were statistically analyzed, and firstly the physical and mechanical properties were correlated with CI and TC, respectively. Positive linear correlations were found between TC and uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), and Schmidt hammer hardness (SHH). When the rock samples were grouped based on their geological origins, there were strong or good linear relationships between CI and UCS and BTS for both the jaw and roll crushers. Then, TC was correlated with CI, d50, and d80. It was found that TC was influential on CI especially for the roll crusher. However, when the rocks were separated as igneous, metamorphic and sedimentary, strong linear relationships were found for both crushers. The same was observed for the relationship between TC and both d50 and d80; the correlation coefficients were higher and more reliable for the roll crusher than the jaw crusher. The results of this study showed that the textural properties of rocks are more influential on the results obtained in a roll crusher than a jaw crusher. However, more rock samples are required to verify the results of this study. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature

The Usability of Noise Level from Rock Cutting for the Prediction of Physico-Mechanical Properties of Rocks

WOS: 000346908300006Because the indirect tests are easier and cheaper than the direct tests, the prediction of rock properties from the indirect testing methods is important especially for the preliminary investigations. In this study, the predictability of the physico-mechanical rock properties from the noise level measured during cutting rock with diamond saw was investigated. Noise measurement test, uniaxial compressive strength (UCS) test, Brazilian tensile strength (BTS) test, point load strength (Is) test, density test, and porosity test were carried out on 54 different rock types in the laboratory. The results were statistically analyzed to derive estimation equations. Strong correlations between the noise level and the mechanical rock properties were found. The relations follow power functions. Increasing rock strength increases the noise level. Density and porosity also correlated strongly with the noise level. The relations follow linear functions. Increasing density increases the noise level while increasing porosity decreases the noise level. The developed equations are valid for the rocks with a compressive strength below 150 MPa. Concluding remark is that the physico-mechanical rock properties can reliably be estimated from the noise level measured during cutting the rock with diamond saw.scientific research project unit of Nigde University [FEB 2009/03]; Alexander von Humboldt FoundationThis study has been supported by the scientific research project unit of Nigde University, under the project number FEB 2009/03. The automatic cutting machine used in the study was financed by Alexander von Humboldt Foundation

Relieved specific energy estimation using FLCM and PLCM linear rock cutting machines and comparison with rock properties

World Tunnel Congress, WTC 2019 and the 45th General Assembly of the International Tunnelling and Underground Space Association, ITA-AITES 2019 -- 3 May 2019 through 9 May 2019 -- -- 226789Specific energy is defined as the amount of work required to break a unit volume of rock and used to predict the performance of mechanical miners. This value can be obtained from full-scaled laboratory linear (FLCM) or portable linear rock cutting (PLCM) experiments at different cut spacings and depths, respectively. For this purpose, full-scaled linear and portable linear rock cutting experiments are performed on 5 different blocks of rock samples including Beige marble, Kufeki limestone, Travertine, Sandstone and Limestone. Cutter forces acting on a cutter in three orthogonal directions (cutting force, normal force, and sideway force) and, specific energy values are measured during testing. In addition, some physical and mechanical property testing are carried out and the relationships between optimum specific energy values and rock mechanical properties are analyzed using regression analysis. Statistical analyses suggest that the relieved specific energy values can be predicted reliably from rock mechanical properties to select the most efficient mechanical miners for a given rock or mineral. © 2019 Taylor & Francis Group, London.Türkiye Bilimsel ve Teknolojik Araştirma Kurumu Istanbul Teknik Üniversitesi ASCRS Research FoundationThis paper is based on the PhD thesis of Ramazan Comakli. The authors are grateful for the support of Istanbul Technical University (ITU) Research Foundation, the Scientific and Technological Research Council of Turkey (TUBITAK 112M859), the company of E-BERK Tunneling and Foundation Technologies for supplying mini discs and all research people involved in this project

NOISE LEVEL MEASUREMENT TEST TO PREDICT THE ABRASION RESISTANCE OF ROCK AGGREGATES

WOS: 000330234800003Compared to the indirect tests, the determination of the Los Angeles abrasion loss is time consuming and expensive, and requires a large amount of samples. For this reason, the prediction of Los Angeles abrasion loss from some indirect tests is useful for preliminary studies. In this study, Los Angeles abrasion, noise level (NL) measurement, density, and porosity tests were carried out on 27 different rock types such as igneous, metamorphic, and sedimentary. The test results were evaluated using the simple and multiple regression analysis. A good relation was found between the Los Angeles abrasion loss and the NL. In order to check the possibility of obtaining more significant relations, multiple regression analysis was performed by including density and porosity values. However, the regression analysis showed that the correlation coefficients of the multiple regression equations were slightly higher than that of the simple regression equation. Since the simple regression equation is practical and statistically significant, it is suggested for estimation purpose. In conclusion, it can be said that Los Angeles abrasion loss of aggregates can be reliably estimated from NL measurement.Scientific Research Project Unit of Nigde University [FEB 2009/03]; Alexander von Humboldt FoundationThis study has been supported by the Scientific Research Project Unit of Nigde University, under the project number FEB 2009/03. The automatic cutting machine used in the study was financed by Alexander von Humboldt Foundation

Comparison of blood carbonic anhydrase activity of athletes performing interval and continuous running exercise at high altitude

The effects of high-intensity interval and continuous exercise on erythrocytes carbonic anhydrase (CA, EC 4.2.1.1) activity levels were scarcely investigated up until now. Here we present a study focused on the CA activity from erythrocytes of athletes experiencing interval and continuous training for 6 weeks, during cold weather and at high altitude (> 1600 m). We observed a 50% increase in the blood CA activity at the second week after initiation of the training in both interval and continuos running groups, whereas the control group did not experience any variation in the enzyme activity levels. In the trained individuals a mild decrease in their body mass, BMI and an increased (Formula presented.) were also observed. The CA activity returned at the basal values after 4–6 weeks after the training started, probably proving that a metabolic compensation occurred without the need of an enhanced enzyme activity. The unexpected 50% rise of activity for an enzyme which acts as a very efficient catalyst for CO2 hydration/bicarbonate dehydration, such as the blood CA, deserves further investigations for better understanding the physiologic basis of this phenomenon. © 2018, © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group