Bulletin of the Geological Society of Malaysia, Volume 49, April 2004, pp. 51 – 55
Pusat Pengajian Sains Sekitaran & Sumber Alam, Fakulti Sains & Teknologi, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor
Abstrak: Penanda Mutu Batuan (RQD) seringkali digunakan sebagai ukuran mutu jasad batuan. Indeks RQD ini dikira berdasarkan peratus jumlah teras gerudi yang diperolehi semasa penggerudian. Nilai RQD mempunyai hubungan secara empirikal dengan jarak retakan dan darjah luluhawa pada jasad batuan. Skema pengelasan jasad batuan yang berdasarkan kepada hubungan diantara nilai RQD dan kualiti jasad batuan telah dikenalkan oleh Deere (1968). Singh & Goel (1999) telah membuat pengiraan nilai RQD menggunakan halaju gelombang mampatan (Vp) yang diukur di lapangan (menggunakan kaedah biasan dan pantulan seismos) dan halaju Vp sampel teras gerudi batuan yang diperolehi melalui ujian ultrasonik di makmal. Kertas kerja ini membincangkan teknik baharu bagi pengiraan nilai RQD menggunakan kaedah analisis spektral gelombang permukaan yang pada masa ini telah digunakan dan dikembangkan untuk menentukan kekukuhan daripada tanah dan jasad batuan serta jalan raya dan konkret. Dalam teknik baharu ini, halaju gelombang ricih (Vs) yang diukur melalui kaedah Analisis Spektral Gelombang Permukaan (SASW) beserta halaju Vs yang diperolehi daripada ujian ultrasonik sampel teras batuan di makmal digunakan bagi mengira nilai RQD melalui persamaan,
RQD (%) = 100(1-δ), dimana δ = [(Vsµ – Vsß)2/(Vsµ + Vsß)2]2
dan Vsβ serta Vsμ adalah halaju gelombang ricih yang diukur dengan kaedah SASW serta ujian ultrasonik. Kaedah baharu ini telah diuji kebolehgunaanya ditiga tapak kajian iaitu Bandar Tasik Selatan, Kepong dan Bandar Sri Damansara dan hasil yang diperolehi bersesuaian (tidak melebihi 10%) dengan nilai RQD yang diperolehi daripada data lubang gerudi.
Abstract: Rock quality designation (RQD) is often utilised as a measure of overall quality of rock mass. The RQD index is based on a modified computation of percent rock core recovery during drilling. The RQD value can be empirically related to the relative frequency of discontinuities and condition of weathering of the rock mass. A rock mass classification scheme based on the relationship between the RQD and rock mass quality has been designed by Deere (1968). Singh & Goel (1999) had calculated the RQD values using compressive wave velocity (Vp) measured in the field (using the conventional refraction and reflection seismics) and compressive wave velocity (Vp) obtained from the standard ultrasonic test of the core samples in the laboratory. This paper describes a new proposed method of RQD computation using Spectral Analysis of Surface Wave (SASW) method which is currently used and developed for determining the stiffness of subsurface soil and rocks as well as for pavement and concrete materials. In this new technique, the velocity of shear wave (Vs) derived from the SASW measurement together with the ultrasonic shear wave velocity test of the core samples in the laboratory were used to compute the RQD values using the following equation,
RQD (%) = 100(1-δ), where δ= [(Vsµ – Vsß)2/(Vsµ + Vsß)2]2
and Vsβ and Vsμ are the shear wave velocities derived from the SASW and ultrasonic velocity test respectively. This new method has been tested at three study sites, Bandar Tasik Selatan, Kepong and Bandar Sri Damansara. The calculated RQD values were in good agreement (within 10% difference) with those of RQD values obtained from the bore hole data.
https://doi.org/10.7186/bgsm49200409
