Sains Malaysiana 43(5)(2014): 751-756

Korelasi Pekali Kekasaran Kekar (JRC) dengan Sudut Geseran Puncak Satah Ketakselanjaran Batuan Granit, Semenanjung Malaysia

(Correlation of Joint Roughness Coefficient (JRC) with Peak Friction Angles of Discontinuity Planes of Granites, Peninsular Malaysia)

T.L. GOH*, A. GHANI RAFEK & M. HARIRI ARIFIN

Program Geologi, Pusat Pengajian Sains Sekitaran dan Sumber Alam, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E. Malaysia

Received: 24 August 2012/Accepted: 19 August 2013

ABSTRAK

Kekasaran permukaan satah ketakselanjaran adalah parameter penting untuk penilaian kestabilan struktur pengorekan dalam jasad batuan kerana ia mempengaruhi tingkah-laku ricihan dan nilai sudut geseran puncak satah tersebut. Beberapa kaedah boleh digunakan untuk menentukan kekasaran permukaan ketakselanjaran. Kertas ini memperkenalkan satu pendekatan yang mudah dalam bentuk tiga (3) persamaan polinominal untuk mengkorelasikan sudut geseran puncak ketakselanjaran (ø_p) batuan granit segar, terluluhawa sedikit dan terluluhawa sederhana dengan pekali kekasaran kekar, (JRC). Persamaan polinominal ketakselanjaran batuan granit segar ialah ø_p1 = -0.071JRC² + 3.56JRC + 35.6. Persamaan polinominal ketakselanjaran batuan granit terluluhawa sedikit dan terluluhawa sederhana masing-masing ialah fp2 = -0.087JRC² + 4.32JRC + 34.1 dan ø_p3 = -0.133JRC² + 5.08JRC + 29. Hasil kajian ini memberikan satu kaedah alternatif penganggaran nilai ø_p satah ketakselanjaran daripada penentuan nilai PKK pada permukaan ketakselanjaran batuan granit di lapangan.

Kata kunci: Granit; pekali kekasaran kekar; sudut geseran puncak; ujian kemiringan

ABSTRACT

Surface roughness is an important parameter in the evaluation of the stability of structures excavated in rock masses as it controls the shear behaviour and the value of the peak friction angle of a discontinuity plane. Several approaches can be adopted for the determination of surface roughness of discontinuities. This paper presents a simple approach in the form of three (3) polynomial equations to correlate the peak friction angle (ø_p) with the Joint Roughness Coefficient (JRC) for discontinuity planes in fresh, slightly weathered and moderately weathered granites. For fresh granite discontinuities, the polynomial equation is fp1 = -0.071JRC² + 3.56JRC + 35.6. The polynomial equations for slightly and moderately weathered granite discontinuities are ø_p2 = -0.087JRC² + 4.32JRC + 34.1 and ø_p3 = -0.133JRC² + 5.08JRC + 29, respectively. These results offer an alternative method for the estimation of the fp of the discontinuity planes by measuring the JRC values of the granite discontinuity planes in the field.

Keywords: Granites; joint roughness coefficient; peak friction angle; tilt test

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*Corresponding author; email: gdsbgoh@gmail.com