Sains Malaysiana 41(3)(2012): 293–297

Korelasi Pekali Kekasaran Kekar dengan Sudut Geseran Puncak Satah Ketakselanjaran Batuan Syis, Semenanjung Malaysia

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

A. Ghani Rafek & M. Hariri Ariffin

Program Geologi, Pusat Pengajian Sains Sekitaran dan Sumber Alam

Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor D.E. Malaysia

T.L. Goh*

Geoscience Department, Subsurface Division, Petronas Research Sdn. Bhd.,

Lot 3288 & 3289, Off Jalan Ayer Itam, Kawasan Institusi Bangi, 43000 Kajang

Selangor D.E. Malaysia

Diserahkan: 26 April 2011 / Diterima: 19 Ogos 2011

ABSTRAK

Kekasaran permukaan amat mempengaruh tingkah-laku ricihan dan nilai sudut geseran puncak sesuatu satah ketakselanjaran. Oleh yang demikian, kekasaran permukaan merupakan faktor yang penting yang perlu dinilai dalam menentukan kestabilan struktur pengorekan dalam jasad batuan. Beberapa kaedah boleh digunakan untuk menentukan kekasaran permukaan ketakselanjaran. Kertas ini memperkenalkan satu pendekatan yang mudah dalam bentuk dua rumus polinominal yang boleh digunakan untuk mengkorelasi sudut geseran puncak ketakselanjaran (φp) batuan syis segar dan terluluhawa sedikit dengan pekali kekasaran kekar, PKK. Rumus polinominal ini ialah φp= -0.022PKK2 + 3.21PKK + 28.1 untuk ketakselanjaran segar dan φp= -0.025PKK2 + 3.24PKK + 26.6 untuk ketakselanjaran terluluhawa sedikit. Kedua-dua rumus ini memperlihatkan nilai pekali penentuan, R2 = 0.98. Hasil kajian ini menawarkan satu kaedah alternatif penganggaran φp satah ketakselanjaran daripada nilai PKK yang diukur pada permukaan ketakselanjaran di lapangan.

Kata kunci: Pekali kekasaran kekar; sudut geseran puncak; syis; ujian kemiringan

ABSTRACT

Shear behavior and value of peak friction angle of a discontinuity plane is strongly controlled by its surface roughness. As such, surface roughness is an important factor to be evaluated in determining the stability of structures excavated in rock body. Several approaches can be adopted for the determination of surface roughness of discontinuities. This paper presents a simple approach, in the form of two polynominal equations to correlate the peak friction angle (φp) with the Joint Roughness Coefficient (JRC) for discontinuity plane in fresh and slightly weathered schists. The polynomial equations are φp= -0.022JRC2 + 3.21JRC + 28.1 for fresh discontinuities and φp= -0.025JRC2 + 3.24JRC + 26.6 for slightly weathered discontinuity. Both equations exhibited coefficient of determination R2= 0.98. These results offer an alternative method to estimate φp of discontinuity planes by measuring the JRC values of the discontinuity planes in the field.

Keywords: Joint roughness coefficient; peak friction angle; schists; tilt test

RUJUKAN

Baizura Yunus, N., Ghani Rafek, A., Goh, T.L. & Hariri Arifin, M. 2009. Quantification of granite rock material weathering grades employing the Schmidt hammer rebound testing: Malaysian examples. Proceeding of Regional Conference on Environmental & Earth Resources pp. 169-174.

Barton, N. 1973. Review of a new shear strength criterion for rock joints. Engineering Geology 7: 287-332.

Barton, N. & Choubey, V. 1977. The shear strength of rock joints in theory and practice. Rock Mechanics 10: 1-54.

Fecker, E. & Rengers N. 1971. Measurement of large scale roughness of rock planes by means of profilograph and geological compass. Rock Fracture, Proc. Int. Symp. Rock Mech, Nancy 1: 18.

Gobbett, D.J. 1964. The lower palaeozoic rocks of Kuala Lumpur, Malaysia. Fed. Museums Jour. 9: 67-70.

Goh, T.L., Ghani Rafek, A., Hariri Arifin, M. & Baizura Yunus, N. 2011. Ujian ricih terus permukaan satah ketakselanjaran granit. Sains Malaysiana 40(5): 419-423.

Hariri Arifin, M., Ghani Rafek, A., Goh, T.L. & Baizura Yunus, N. 2009. The use of Schmidt rebound hammer as a method to estimate the degree of weathering for metamorphic rocks from Malaysia. Proceedings of Regional Conference on Environmental and Earth Resources pp.175-180.

ISRM. 1981. Rock Characterization, Testing and Monitoring. ISRM Suggested Methods, Dlm. Brown (pnyt.), Oxford: Pergamon Press. pp. 101.

Oh, H.T. 2008. Pemetaan geologi sepanjang KM14-KM27 Jalanraya Kg. Raja, Cameron Highland, Pahang – Pos Selim, Perak. Tesis Sarjana Muda Sains, Universiti Kebangsaan Malaysia (tidak diterbitkan).

Patton, F.D. 1966. Multiple modes of shear failure in rock. Proceedings 1st International Congress of Rock Mechanics, Lisbon 1: 509-513.

Priest, S.D. 1993. Discontinuity Analysis for Rock Engineering. London: Chapman & Hall.

Supiah Mukhtar. 2007. Pencirian geomekanik jasad batuan syis amfibol di KM 15 jalan baru Kuala Kubu Bahru-Bukit Fraser, Selangor. Tesis Sarjana Muda Sains Universiti Kebangsaan Malaysia (tidak diterbitkan).

Zhao, J. 1997a. Joint surface matching and shear strength, Part A: Joint matching coefficient (JMC). Int. J. Rock Mech. Min. 34(2): 173-178.

Zhao, J. 1997b. Joint surface matching and shear strength, Part B: JRC-JMC shear strength criterion. Int. J. Rock Mech. Min. 34(2): 179-185.

*Pengarang untuk surat-menyurat; email: gdsbgoh@gmail. com