Chau K.T. and Wong R.H.C. (1996) "Uniaxial compressive strength and point load strength of rocks" International Journal of Rock Mechanics and Mining Science & Geomechanics Abstract, Vol. 33, No. 2, February, pp. 183-188 (SCI journal published by Elsevier). (original) (raw)
Related papers
Point-load strength: An index for classification of rock material
Bulletin of the International Association of Engineering Geology, 1991
Point-load strength (Is) as a measure for the determination of rock strength and for estimating uniaxial (unconfined) compressive strength (UCS) are described and both put together and used for rock strength classification of brittle and hard rocks. The estimated point-load strength values of ~,pecimuns of ',';trying sizes and also the ',alue~, corrected t,) a standard thickness (d" 50 ram, and die resultant point-load strength ,,,;dues (Is-50) have been used tt~ estimate the uniaxial (unconfined) compre~,sive strength which c~wrelates well v. ith actual recorded uniaxial (unconfined) compression test results. Using graphical and mathematical relations, hips between the obser'~ed and estimated tICS and ls values, a conversion factor of 16 is obtained for estimating uniaxinl (unconfincdl compressixe strengtb ',';dues from point load strength resulb, A nomogram for computing point-load strength index and a system for the classification of rock material are presented. Rdsumd La resistance au fendage sous charge ponctuelle (Is) constitue une d.valuation de ]a resistance de la roche et permet d'estimer la resistance en compressi~m uniaxiale (UCS): les deux ess;,is sont utilis,Ss pour dtablir une classification des roches rdsistantes de type fragile. l_es valeurs de resistance au fendage sous charge ponctuelle rdalisdes sur des dchantilhms de differentes tallies, ainsi que les valeurs ramendes par corrections :', une dpaisseur standard de 50 mm fournissent une valeur resultante Is-50 qui a ere utilisde pour estimer la resistance en compression uniaxiale a,,ec uric bonne correlation. En utilisant des comparaisons graphiques et math,Smatiques entre les valeurs UCS et b,. un facteur de conversion de 16 est obtenu pour a;oir la valeur UCS b. partir de la valeur Is. Un nomogramme pour calculer la valeur de resistance au fendage sous charge ponctuelle, et un syst~me de classification des roches son presentes.
Correlation between uniaxial strength and point load index of rocks
Japanese Geotechnical Society Special Publication, 2016
Determination of rock engineering properties is important in civil, mining and geotechnical engineering. Uniaxial Compressive Strength (UCS) is one of the most important properties of rocks. Point Load Test (PLT) is practically used in geotechnical engineering to determine rock strength index. Despite that the PLT is fast, economical and simple in either field or laboratory, Uniaxial Compressive Test (UCT) is time-consuming and expensive. UCS can be estimated using Point Load Index (PLI). So, implementation of correlation between results of PLT and UCT is of interest. In this research correlation between the results of point load test and uniaxial compressive test are presented for rock samples from three sites in Iran. Two rock types including Shale and Marlstone have been utilized in this research. Correlations between UCS and PLI in this study are verified with proposed equation by pervious researchers.
A Unified Strength criterion for rock material
A non-linear Unified Strength criterion for rock material is presented. It is the development of the Unified Strength Theory (in: M. Jono, T. Inoue (Eds.), Mechanical Behaviour of Materials-VI (ICM-6), Pergamon, Oxford, 1991, pp. 841-846) and the modification of the Hoek-Brown strength criterion (Underground Excavations in Rock, The Institution of Mining and Metallurgy, London, 1980). The effect of intermediate principal stress on rock strength is considered in the non-linear Unified Strength criterion. The
Evaluation of empirical methods for measuring the uniaxial compressive strength of rock
International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1990
Eight sandstones, three limestones, one dolomite, one marble and one syenitic gneiss were tested to evaluate the correlations between the compressive strength values, as determined by the standard uniaxial compression test, and the corresponding results of the point load, the Schmidt hammer, the Los Angeles abrasion, and the slake durability tests. Ten cores of each rock type were used for the uniaxial compression, point load and Schmidt hammer tests, whereas an average of three tests for each rock type was used to determine the Los Angeles abrasion loss and the slake durability indices. Results indicate that strong linear correlations exist between the results of uniaxial compression vs the point load and Schmidt hammer tests, the correlation for the Schmidt hammer being dependent on rock type. The correlation between uniaxial strength and the Los Angeles abrasion loss in non-linear but becomes linear when a log-log scale is used. The slake durability index does not exhibit a significant correlation with the uniaxial strength for the rocks tested. The correlation equations for predicting compressive strength using different methods are presented along with their confidence limits. All empirical tests used, other than the slake durability test, provide reliable estimates of compressive strength, with Schmidt hammer slightly underestimating at higher strength (> 150 MPa).
Characterizing Intact Rock Strength using Field Estimates and the Point Load Index Test
A number of guidelines for the field estimate of intact rock strength are available. Although all vary slightly in terms of the boundaries of the strength classes, they generally rely on reaction to a number of simple index tests. The errors and uncertainties associated with estimation of strength using these schemes are high and strength estimates need to be treated with caution. Undertaking point load index testing in the field is a useful tool that can provide data to augment field strength estimates and laboratory test data. Field point load index test data can be converted to an equivalent uniaxial compressive strength (UCS) but this relationship should be calibrated through twinned UCS and point load index tests. A case study is presented for an investigation in highly anisotropic banded iron formation of the Hamersley Province, West Australia. The relationship between UCS and point load index strength for the site is shown to be strength dependent. The calibrated field point load index test data is provides additional information on the variability of the rock strength that could not be captured by limited laboratory testing.
Scale effects in rock strength properties
In rock mechanics and engineering geology, the point load test often serves as a "last chance" for estimating the unconfined compressive strength − when core samples cannot be gained out of faulted or weathered rock mass, − when a value for foliated metamorphic rock has to be obtained perpendicular to schistosity and foliation is inclined in the cores, or − when the strength of small components is to be determined for special purposes e.g. drilling or cutting problems. Since the test is very simple, problems arise due to calculation of the point load strength, standardization of specimen shape and size and the calculation of the unconfined compressive strength out of the point load index.
Determination of the uniaxial compressive strengths of rocks
Soviet Mining Science, 1970
The most used parameter in rock engineering practice is the Uniaxial Compressive Strength (UCS). It is often estimated on the field or trough Index-to-strength conversion factors proposed by various researchers for a specific rock type. The research presented in the paper involved field estimation of Uniaxial Compressive Strength using Schmidt rebound hammer and Point Load laboratory testing on limestone rock samples. The results of the estimated UCS were compared to the Uniaxial Compression Strength laboratory testing results on limestone specimens taken from the same location, in order to compare corresponding UCS of limestone rocks. These results can contribute to better estimation of the local design parameters, when direct determination of the UCS in the laboratory is not possible, rather than adopting the values from around the world case studies.
Point load testing is used to determine rock strength indexes in geotechnical practice. The point load test apparatus and procedure enables economical testing of core or lump rock samples in either a field or laboratory setting. In order to estimate uniaxial compressive strength, index-to-strength conversion factors are used. These factors have been proposed by various researchers and are dependent upon rock type. This study involved the extensive load frame and point load testing of coal measure rocks in six states. More than 10,000 individual test results, from 908 distinct rock units, were used in the study. Rock lithologies were classified into general categories and conversion factors were determined for each category. This allows for intact rock strength data to be made available through point load testing for numerical geotechnical analysis and empirical rock mass classification systems such as the Coal Mine Roof Rating (CMRR).