Sains Malaysiana 40(5)(2011): 419–423

Ujian Ricih Terus Permukaan Satah Ketakselanjaran Granit

(Direct Shear Test of Granite Discontinuity Plane Surfaces)

T. L. Goh*, A. Ghani Rafek, M. Hariri Ariffin & N. Baizura Yunus

Program Geologi, Pusat Pengajian Sains Sekitaran dan Sumber Alam

Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor D.E., Malaysia

Diserahkan: 5 Januari 2010 / Diterima: 14 April 2010

ABSTRAK

Parameter kekuatan ricih seperti sudut geseran permukaan ketakselanjaran batuan merupakan antara data penting bagi reka bentuk struktur kejuruteraan batuan seperti pengorekan bawah tanah dan cerun potongan. Ujian ricih terus beban normal tetap telah dilakukan pada permukaan buatan potongan gergaji batuan granit segar dan terluluhawa sedikit untuk menentukan sudut geseran asas permukaan satah ketakselanjaran. Sampel granit diperoleh dari Kuari Kajang Rock, Semenyih, Ulu Langat, Selangor, Lebuhraya Silk Kajang (km 14.6), Selangor, Jalan Pos Selim-Kampung Raja (km 30-29), Cameron Highland, Pahang/Perak dan Kuari JKR Bukit Penggorak, Kuantan, Pahang. Sebanyak 84 ujian ricih terus telah dijalankan pada batuan granit iaitu 65 ujian pada batuan segar dan 19 ujian pada batuan terluluhawa sedikit. Untuk batuan granit segar, sudut geseran asas ialah 42° ± 0.6° dengan sisihan piawai sebanyak 2.26 dan pekali penentuan, R2 sebanyak 0.98. Untuk granit terluluhawa sedikit, sudut geseran asas ialah 38° ± 1.9° dengan sisihan piawai sebanyak 3.99 dan pekali penentuan, R2 sebanyak 0.97. Nilai-nilai ini adalah lebih tinggi daripada nilai yang selalu dianggap untuk batuan granit segar iaitu 30°-35°.

Kata kunci: Granit; sudut geseran asas; ujian ricih terus

ABSTRACT

Shear strength parameters such as friction angle of discontinuity surfaces of rock are among the essential data for the design of rock engineering structures like underground excavation and cut slopes. Constant normal load direct shear test has been employed on artificially sawn surfaces of fresh and slightly weathered granite to determine the basic friction angle of the discontinuity plane surfaces. The granite samples were collected from Kajang Rock Quarry, Semenyih, Ulu Langat, Selangor, Kajang Silk Highway (km 14.6), Selangor and Pos Selim-Kampung Raja road (km 30-29), Cameron Highland, Pahang/Perak and JKR Quarry Bukit Penggorak, Kuantan, Pahang. A total of 84 direct shear tests were carried out, comprising 65 and 19 tests on fresh and slightly weathered granite, respectively. For fresh granite, the basic friction angle is 42° ± 0.6° with standard deviation of 2.26 and coefficient of determination, R2 of 0.98. For slightly weathered granite, the basic friction angle is 38° ± 1.9° with standard deviation of 3.99 and coefficient of determination, R2 of 0.97. These values are considerably higher than the often assumed value of 30°-35° for fresh granite.

Keywords: Basic friction angle; direct shear test; granite

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