It measures the percentage of good rock within a borehole. Engineering judgement may be necessary to determine if a piece of core qualifies as being intact. Response of rocks to applied loads earth materials rocks. Rock mass classification 5 deeres rqd was widely used, particularly in north america, after its introduction. Read using rqd to estimate the deformation modulus of rock masses, international journal of rock mechanics and mining sciences on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Rock mechanics sectional committee, ced48 foreword this indian standard part i was adopted by the bureau ofindian standards, after the draft finalized by the rock mechanics sectional committee had been approved by the civil engineering division council. Pdf determination and applications of rock quality designation. Engineering application of rock mass classifications systems proceedings of 24th thiserd international conference, seoul, south korea, january 2016, isbn. Modular ratio for limepop mix double joint specimen. Rock quality designation rock quality designation rqd 2 is a fracture index used in many rock classification systems.
Samani fb, goudarzi mt 2006 a proposal for the modification of rqd mrqd. Core recovery and rqd rock quality designation the easiest way to characterize the amount of material recovered during rock coring is to calculate core recovery as the amount i. This is useful knowledge for engineers in the design of foundations for structures, during dam building and tunneling for road or. Pdf rock quality designation rqd was introduced by don deere in the. Determination and applications of rock quality designation rqd. Rqd is defined as the percentage of intact core pieces longer than 100 mm 4 inches in the total length of core. Rock mechanics concerns the behavior of rock when such rock is subjected to forces that are either natural or those applied to the rock by engineers when they build their structures or other applications that use the qualities of the rock for their own purposes.
It means rock quality designation and representative cross sections of the core sample must reach, or exceed 90 100 mm in length for it to be considered excellent in. The empirical methods based on rqd provide a convenient way for estimating the mechanical properties of rock masses but, whenever possible. Rqd rock quality designation rock mass classification rsr rock structure rating rock mass classification rmr rock mass rating rock mass classification viii rmr basic. American society for testing and materials reprinted from the. The recording of rqd has since become virtually standard practice in drill core logging. Many researches have been conducted to relate rqd and rock mass fracture. Rock quality designation rqd rough is the measure of the degree of jointing or fractures in a rock mass, measured as a percentage of the drill core in lengths of 10 cm or more.
Feb 27, 2015 great geotech problem for the pe exam. Rock quality designation rqd 2 is a fracture index used in many rock classification systems. Rock quality designation, rqd, is based on core recovery procedure which, in turn, is based indirectly on the number of fractures and amount of softening or alteration in the rock mass as observed in the rock cores. Milne university of saskatchewan, saskatoon, canada j. Rock quality designation rqd, was introduced by don deere in the mid1960s as a means of using diamond core to classify rock for engineering purposes. Determining rock quality designation rqd of rock core1 this standard is issued under the. Since in many cases rock quality designation rqd is the onlyrock mass classi.
Since in many cases rqd is the only information available for describing rock discontinuities, this paper focuses on the determination of rqd and its utilization for evaluating the engineering properties mainly deformation modulus and unconfined compressive strength of rock masses. Highquality rock has an rqd of more than 75%, low quality of less than 50% table 1. Proceeding of 4th asian rock mechanics symposium, rock mechanics in underground construction. Terminology and descriptions for discontinuities general. Rockquality designation rqd rough is the measure of the degree of jointing or fractures in a rock mass, measured as a percentage of the drill core in lengths of 10 cm or more. Standard test method for determining rock quality designation. American society for testing and materials reprinted from. Pakalnis the university of british columbia, vancouver, canada abstract.
Using rqd to estimate the deformation modulus of rock masses. When evaluating rock core, the engineering geologist should make note of the following. Introduction rock quality designation rqd, uniaxial compression strength ucs, hardness and rock abrasion all place a significant role in rock mechanics. Rock quality designation rqd was introduced by don deere in the mid1960s as a means of using diamond core to classify rock for engineering purposes. Rock slope stability assessment through rock mass classification systems, international journal of rock mechanics and mining sciences, 462, 315325. Determining rock quality designation rqd of rock core1. Rock mass characterization for underground hard rock mines. Insitu characterization of rocks 4 rock mass is a volume of rocks intersected by discontinuities. Determination and applications of rock quality designation rqd author links open overlay panel lianyang zhang. Today rqd is used as a standard parameter in drill core logging and forms a basic element value of the major mass classification systems. Rock quality designation rqd is a standard technique in the mining industry for the qualitative and quantitative assessment of rock quality and degree of jointing, fracturing, and shearing in a rock mass.
A proper description of rock obtained in drill cores is a valuable aid to the engineering geologist in determining the properties of bedrock with regard to rock slope and structure foundation design. Local and general shear failure is associated to brittlegeneral shear failure is associated to brittle and ductile rock respectively. Bearing capacity of rocks intact rock massintact rock mass a rock mass with joint spacing greater than 4 to 5 times the width of the footing. Astm 2008 standard test method for determining rock quality designation rqd of. Rock mass rating bieniawski 1976 published the details of a rock mass classification called the geomechanics classification or the rock mass rating rmr system. Rock quality designation rqd is a rough measure of the degree of jointing or fracture in a rock mass, measured as a percentage of the drill core in lengths of 10 cm or more. What is the bearing capacity of rock on surface an at depths.
Rqd is an acronym for a technique that is used in geotechnical engineering principles in which that determines the quality of rock that was recovered when taking a core sample. Since in many cases rock quality designation rqd is the only. Using rqd to estimate the deformation modulus of rock. Over the years, this system has been successively re fined as more case records have been examined and the reader should be aware that bieniawski has made significant changes in the.
A number in parentheses indicates the year of last reapproval. Rock mechanics problemsrock mechanics problems how will rock react when put to mens use. The engineering geologist is responsible for the determination of rqd. The rqd is a modified core recovery percentage in which unrecovered core, fragments and small pieces of rock, and altered rock are not counted so. Rock mechanics sectional committee had been approved by the civil engineering division council. When properly carried out, rqd forms a basic element in most used rock mass classification systems in engineering geology and geotechnical engineering. Estimation of gsi in terms of rqd and joint condition scale a in figure 2 represents discontinuity surface conditions while scale b represents the blockiness of the rock mass. In this post, i will take you through the process of calculating the hoekbrown failure criteria in.
This paper was prepared for presentation at the 47th us rock mechanics geomechanics symposium held in san francisco, ca, usa, 2326 june 20. Genesis and definition of rock mass designation rqd in 1964 and 1965, whilst working on sites in granite at the nevada test site for nuclear bombs, deere and coworkers see deere 1968 and deere and deere 1989 devised an index, rqd, to differentiate between relatively good quality rock and poor rock when logging rock core, as an alternative to just judging quality on the basis of core recovery. Simple correlations between rock abrasion and other. Rock mass rating basic value, rmr for dry conditions and no adjustment for joint orientation rmr 76 rock mass rating based on the version from 1976 q the rock mass quality system rock mass classification, ngiindex q a modified qsystem, which is stress reduction free and where the ratings given for joint orientation are ignored. Rocky ground is rock mass subjected to stresses and ground water. Rock quality designation an overview sciencedirect topics.
Characterization of rock masses and evaluation of their mechanical properties are important and challenging tasks in rock mechanics and rock engineering. Use and misuse of rock mass classification systems with particular reference to the qsystem 5 2. The rock quality designation rqd index was introduced 20 years ago at a time when rock quality information was usually available only from geologists descriptions and the percent of core recovery. The rqd is an index of rock quality in which a modified core recovery per. Hadjigeorgiou universite laval, quebec city, canada r. One indicator of rock quality and the degree of fracturing is a simple characterization known as the rock quality designation rqd. In this post, i will take you through the process of calculating the hoekbrown failure criteria in python. Rqd was intended as more than an index of fracture spacing. Characterization is the process of giving numerical values to rock mass features such as joint density, joint roughness, rock type, etc. In the context of this discussion, the most important use of rqd is as a component of the rmr and q. Highquality rock has an rqd of more than 75%, low quality of less than 50%. Division geotechnical manual which is as described by. Rock quality designation rqd is a modified core recovery percentage in which the lengths of all sound.
A new method for improving the rqd determination of rock. Rock mechanics is the theoretical and applied science of the mechanical behaviour of rock and rock masses. Oct 18, 2012 an instructional video about rqd, a strength determining technique used by geologist and geological engineers. Cording and deere 1972, merritt 1972 and deere and deere 1988 attempted to relate rqd to terzaghis rock load factors and to rockbolt requirements in tunnels. Subsequently, it was incorporated into the rock mass rating rmr and q system classification methods that, worldwide, now play substantial roles in rock mechanics design, whether for tunnels.
Many variations and it s impossible to know them all for any rock mass. The rqd in percent is obtained by dividing the sum of all the. The qsystem for rock mass classification is developed by barton, lien, and lunde. Rock quality designation rqd has several definitions. A simple guide to calculate the hoekbrown failure criteria. Study of scale effects of rock quality designation rqd. What is the response of rocks under dynamic earthquake type loading. Assessment of the quality of rock mass rqd rock quality designation, table 7. Like rqd, hardness exhibits the quality of the rock where the. Rock quality designation rqd is a measure of quality of rock core taken from a borehole. It is a leading indicator for lowquality rock zones. To determine the rqd value, add the total length of solid core that is 4 inches 100 mm or more long regardless of core diameter. The first term rqd rock quality designation divided by j n. Rock quality designation index rqd the rock quality designation index rqd was developed by deere deere et al 1967 to provide a quantitative estimate of rock mass quality from drill core logs.
Prediction of side resistance in poor quality rock. In deeres words from 1989, rqd is an index of rock quality in that problematic rock that is highly weathered, soft, fractured, sheared, and jointed is counted against the rock mass. Rock mass characterization for underground hard rock mines d. Study of scale effects of rock quality designation rqd measurements using a discrete fracture network approach by rongzhen wang b. Rqd even though they possess the requisite 4 in, 100mm length. Rqd was introduced for use with core diameters of 54. Field group sub roup drill core rock classification rqd fracture frequency rock mechanics ins. Feb 01, 2004 read using rqd to estimate the deformation modulus of rock masses, international journal of rock mechanics and mining sciences on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
Rock mass characterization is an integral part of rock engineering practice. Note therock mass quality in equation 1 is rela ted with the ultimate support pressure requirements. Lectures on rock mechanicslectures on rock mechanics. An instructional video about rqd, a strength determining technique used by geologist and geological engineers. Rqd is defined as the percentage of intact drill core pieces longer than 10 cm recovered during a single core run abzalov, 2016, and the general equation is expressed as. D6032 d6032m17 standard test method for determining rock quality designation rqd of rock core rock quality designation drill cores geophysical logging classification rock cores. The soil profile rock or soil material, derived by geologic processes, are subject to physical and chemical changes brought.
Pdf determination and applications of rock quality. What is rqd rock quality designation and how to calculate it. Engineers and geologists must take this effect into account to predict failure in slope faces and tunnel excavations. Characterization is the process of giving numerical values to rock mass features such as joint density. Fracture frequency rock mechanics insitu modulus rock auality 19, abstract continue on reverse if necessary and identify by block number twenty years of experience is now available in the use of the rock quality designation rqd in practice. Determination and applications of rock quality designation. It expresses the quality of the rock mass in the socalled qvalue, on which are based design and support recommendations for underground excavations. Quantitative classification ofrock masses has many advantages. Determination and applications of rock quality designation rqd article pdf available in journal of rock mechanics and geotechnical engineering 83 march 2016 with 4,380 reads. The rock quality designation rqd is a modified measure of recovery, calculated in order to estimate the quality of the intact rock mass. Abstract continue on reverse if necessary and identify by bock number twenty years of experience is now available in the use of the rock quality designation rqd in practice. The rqd is an index of rock quality in which a modified core recovery per centage is.
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