Cerchar Abrasivity Index Research Articles

Predicting the Performance of Chain Saw Machines Based on Shore Scleroscope Hardness

Shore hardness has been used to estimate several physical and mechanical properties of rocks over the last few decades. However, the number of researches correlating Shore hardness with rock cutting performance is quite limited. Also, rather limited researches have been carried out on predicting the performance of chain saw machines. This study differs from the previous investigations in the way that Shore hardness values (SH1, SH2, and deformation coefficient) are used to determine the field performance of chain saw machines. The measured Shore hardness values are correlated with the physical and mechanical properties of natural stone samples, cutting parameters (normal force, cutting force, and specific energy) obtained from linear cutting tests in unrelieved cutting mode, and areal net cutting rate of chain saw machines. Two empirical models developed previously are improved for the prediction of the areal net cutting rate of chain saw machines. The first model is based on a revised chain saw penetration index, which uses SH1, machine weight, and useful arm cutting depth as predictors. The second model is based on the power consumed for only cutting the stone, arm thickness, and specific energy as a function of the deformation coefficient. While cutting force has a strong relationship with Shore hardness values, the normal force has a weak or moderate correlation. Uniaxial compressive strength, Cerchar abrasivity index, and density can also be predicted by Shore hardness values.

세르샤 마모시험을 통한 암석의 마모도 측정에 관한 연구

본 연구에서는 암석 절삭 장비의 마모에 직접적인 영향을 주는 인자인 암석의 마모도(abrasiveness) 측정에 관한 연구를 수행하였다. 몇 가지 방법 중 세르샤 마모 시험(Cerchar abrasiveness test)을 통하여 암석의 마모도에 영향을 미치는 인자를 확인하고 효율적인 시험을 수행하기 위한 조건들을 연구하였다. 국내 19종 암석에 대한 시험 결과를 통하여, 세르샤 마모 지수(CAI, Cerchar Abrasiveness Index)에 영향을 미치는 암석의 역학적 물성(단축압축강도, 간접인장강도, 탄성계수, 포아송비, 공극률, 쇼어경도)과의 상관관계를 찾아보았고 X선 회절 분석을 통하여 암석의 구성 광물 중 마모도에 가장 큰 영향을 미치는 석영 함량, 등가 석영 함량과의 관계도 확인하였다. 그 결과로 암석의 입자 결합 특성보다 광물의 특성이 CAI에 영향을 더 미치는 것으로 관찰되었고, 단축압축강도와 등가 석영함량의 함수로 CAI를 예측하는 모델을 제시하였으며 핀의 경도가 커질수록 CAI값이 선형적으로 작아짐을 확인하였다. 수치해석적 연구를 통해 세르샤 마모 시험을 모사한 결과 초기 긁힘 거리에서 대부분의 마모가 발생함을 확인하였고 하중이 증가할수록 CAI값이 증가함을 확인하였다. Abrasiveness of rock plays an important role on the wear of rock cutting tools. In this study, Cerchar abrasiveness tests were carried out to assess the abrasiveness of 19 different Korean rocks. Cerchar abrasiveness test is widely used to assess the abrasiveness of rock because of its simplicity and inexpensive cost. This study examines the relationship between Cerchar Abrasiveness Index (CAI) and mechanical properties (uniaxial compressive strength, Brazilian tensile strength, Young's modulus, Poisson's ratio, porosity, shore hardness of rock), and the effect of quartz content, equivalent quartz content, which was obtained from XRD analysis. As a result of test, CAI was more influenced by petrographical properties than by the bonding strength of the matrix material of rock. CAI prediction model which consisted of UCS and EQC was proposed. CAI decreased linearly with the hardness of the steel pin. Numerical analysis was performed using Autodyn-3D for simulating the Cerchar abrasiveness test. In the simulations, most of pin wear occurred during the initial scratching distance, and CAI increased with the increase of normal loading.

Cerchar abrasivity index (CAI) and its relation to strength and abrasion test methods for marble stones

The Cerchar abrasivity index (CAI) is the most widely known test method for identification of rock abrasivity. The CAI value is related directly to cutter life in the field. On account of this, it is significant for building and constructions materials especially for the dimension stones. This paper presents strength tests, which are uniaxial compressive (UCS) and direct shear (DSS) influencing the CAI value. Additionally, the relationship between CAI and abrasion test methods that are Bohme abrasion (BA) and Wide-Wheel (WW) values are investigated. In the study tests were performed on 15 different marbles stone specimens. Results show that a strong correlation exists between CAI value, strength and abrasion test values. Based on this information, two converter charts were developed using multi regression analysis method.

The usability of Cerchar abrasivity index for the prediction of UCS and E of Misis Fault Breccia: Regression and artificial neural networks analysis

The derivation of some predictive models for the geomechanical properties of fault breccias will be useful due to the fact that the preparation of smooth specimens from the fault breccias is usually difficult and expensive. To develop some predictive models for the uniaxial compressive strength ( UCS) and elastic modulus ( E) from the indirect methods including the Cerchar abrasivity index ( CAI), regression and artificial neural networks ( ANNs) analysis were applied on the data pertaining to Misis Fault Breccia. The CAI was included to the best regression model for the prediction of UCS. However, the CAI was not included to the best regression model for the prediction of E. The developed ANNs model was also compared with the regression model. It was concluded that the CAI is a useful property for the prediction of UCS of Misis Fault Breccia. Another conclusion is that ANNs model is more reliable than the regression models.

Correlating index properties of rocks with P-wave measurements

Abstract The determination of index properties of rock, such as Cerchar Abrasivity Index, Shore Hardness, Protodyakonov Index and Vickers Hardness in laboratory or insitu conditions is time-consuming and requires special equipment and expertise. However, the use of P-wave technology to measure the P-wave velocity of rock is a relatively simple task because the portable equipment can be used in the laboratory or in the field without tedious preparation of rock cores and it is non-destructive. This paper presents an experimental study of the measurement of P-waves of several types of igneous, sedimentary and metamorphic rock. The index properties were also determined in the laboratory to obtain correlations between P-waves and various index properties. Good linear relationships were found between all the index properties determined and the P-wave measurements.

The Influence of the Parameter “Temperature” on the Abrasiveness of Rock

AbstractThe article deals with the influence of temperature produced in the cutting process on rock abrasiveness and tool wear. Basically it was to clarify which effects take place when quartz or rock with significant quartz content is heated up to a certain temperature. Does the quartz jump from low into high quartz happening at 573 °C cause an increase in abrasiveness of mineral and rock or not? To find out, a certain number of Cerchar abrasiveness index tests were done for a detailed investigation of this topic. Additionally, to get a better understanding what really happens inside rock structure additionally other rock parameters like unconfined compressive strength, Brazilian tensile strength, ultrasonic wave velocity and density were determined on untreated and heated and subsequently cooled down rock samples. The final output of the research work showed that rocks show a very specific and significant reaction to thermal stresses induced into their structure resulting in a different behaviour regarding abrasiveness and fracturing.

A study of rock abrasivity and tool wear in Coal Measures Rocks

This paper examines the relations between Cerchar abrasivity index (CAI) and petrographic properties of Coal Measures Rocks in the Zonguldak Coal Basin, Turkey. In this study, petrographic properties and abrasivity indices of 29 sedimentary rock samples were determined and the values of CAI and petrographic analysis results were compared. A good linear relationship between CAI and average quartz grain size parameters was found. The test results also showed that abrasivity was affected by the mineralogical composition, cement type, degree of cementation, quartz content, and average quartz grain size. It was found that abrasivity of rock was decreased by the low grade of cementation between abrasive minerals. CAI values and petrographic properties were used to estimate tool consumption in underground works in the Zonguldak Coal Basin. It was observed that when CAI values increased, tool consumption increased.

Stress dependency of the Cerchar abrasivity index (CAI) and its effects on wear of selected rock cutting tools

The abrasiveness of rocks is often described by the Cerchar abrasivity index CAI. However, the state of stress of the rock sample with the standard CAI test in the laboratory is different from the state of stress of rock to be excavated at the face of any underground opening. Until this work, no attempt has been made to estimate if and how the CAI is effected by in situ stresses. This paper demonstrates that the CAI is definitely stress-dependent. A novel test procedure in which the CAI tests is conducted on samples in a triaxial cell shows the stress dependency for various rock types by higher CAI values upon confining pressure. Additionally, the states of stress at the face of different underground openings are discussed and application of the elevated CAI values for estimating wear of roadheader picks and TBM discs is given.

Abrasivity characteristics of rocks from India and Nepal

Over the years, many attempts have been made to define and characterise rock abrasiveness. However, it is found that abrasiveness of rocks is not only difficult to define but also hard to measure. A number of relative rock abrasiveness tests have emerged but their results do not always faithfully reflect the characteristics of the rocks that may be useful in the excavation process. Under the circumstances, an in­ depth study of rock abrasiveness is warranted. The present study may provide additional help to fill a gap in this area.
 The study has addressed a number of issues on abrasivity of rocks and the objectives included inter-alia the following: 1. Developing and standardising appropriate testing techniques for evaluation of the abrasiveness and microhardness of the mine rocks. 2. Evaluating the abrasivity characteristics of mine rocks from Mosaboni copper mine, Jhinkpani limestone quarry and Indian coal-measure strata, Jharia, all from the Bihar State of India. 3. Evaluating the characteristics of a suite of rocks from Nepal (limestone from Nigale and quartzite from Bhedetar, Dhankuta District, Nepal).
 In this study a number of testing methods have been used to evaluate rock abrasiveness of rocks, specially the Cerchar Abrasivity Index (CAI), Schimazek Index and Indian School of Mines Abrasivity Test (ISMAT). The tests were performed in the rock mechanics laboratory of Indian School of Mines (ISM), Dhanbad, India. The results of these tests are discussed in detail. Hopefully, this study on abrasivity characteristics of rocks will aid in the selection of appropriate tools and excavation systems thereby enhancing the work performances and reducing the costs in excavations.

A model of tunnel boring machine performance

A mathematical model for the performance of a tunnel boring machine (TBM) is presented. In particular an equation for the TBM cutter wear is proposed. The rock mechanics are described via simple strength parameters and the Cerchar abrasivity index (CAI). Thus one obtains a complete description of TBM tunnelling with instantaneous and accumulated values for the tunnelling rate, the tool consumption, the costsetc. as output parameters when the tunnelling proceeds through rock with variable properties (strength and CAI). Two different types of cutter tools are considered, namely wedge-shaped tools and constant wear flat tools. For wedge-shaped tools the tunnelling costs are shown to be minimized if old tools are replaced by new tools when a certain wear flat tool has been reached. Similarly there is an optimum design (=wear flat) for the constant wear flat tools.

Cerchar abrasivity index and its relation to rock mineralogy and petrography : Rock Mech, V15, N1, June 1982, P1–8

Cerchar abrasivity index and its relation to rock mineralogy and petrography : Rock Mech, V15, N1, June 1982, P1–8

The Cerchar Abrasivity Index and its relation to rock mineralogy and petrography

The Cerchar Abrasivity Index and Its Relation to Rock Mineralogy and Petrography To evaluate the relation between the Cerchar Abrasivity Index (a parameter used in calculating advance rates of full face tunnelling machines) and the petrography of the rocks, measurements were made on minerals and monomineralic rocks. From these data a theoretical abrasivity (quartz equivalence) can be calculated for every rock composition. From the comparison of the theoretical and experimentally determined abrasivity the influence of fabric and other factors besides mineralogical composition were deduced.

Friction and wear : F. T. Barwell, Proc. South Wales Inst. Engrs., 81 (2) (1966) 33–48; 7 figs., 3 tables, 51 refs

Schmidt hammer hardness values (SHH1, SHH2, and deformation coefficient) are used to determine the performance of large diameter circular saws. The measured Schmidt hammer hardness values are correlated with the physical and mechanical properties of natural stones and areal slab production rates of large diameter circular saws. Two statistical models for prediction of the areal slab production rates for these machines are developed, which is very important in decision making for engineers. A simple statistical model is suggested taking into account the deformation coefficient and a multiple regression model is also suggested by using the deformation coefficient and Cerchar abrasivity index. The reliability of these models is tested against actual performance of large diameter saws. Verifications and comparisons showed that the models suggested in this study may be a very useful and reliable tool for prediction of areal slab production rates for large diameter circular saws.