Sains Malaysiana 41(2)(2012): 193–198

Kekuatan Geomekanik Batuan Granit dan Syis di Semenanjung Malaysia

(Geomechanical Strength of Granites and Schists of 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

Received: 12 April 2011 / Accepted: 19August 2011

ABSTRAK

Kekuatan geomekanik bahan batuan memainkan peranan penting dalam mempengaruhi kestabilan struktur seperti pemotongan cerun dan pengorekan bukaan dalam jasad batuan. Ciri kekuatan jasad batuan di mana struktur-struktur ini dibina adalah dipengaruh oleh ciri bahan dan keadaan luluhawa. Kertas ini memperkenalkan hasil kajian sistematik pengkuantitatifan ciri-ciri mekanik batuan granit dan syis segar dan terluluhawa sedikit daripada beberapa lokaliti di Semenanjung Malaysia. Sejumlah 1,013 ujian kekuatan geomekanik telah dijalankan untuk bahan batuan segar dan terluluhawa sedikit dengan menggunakan ujian kekuatan mampatan sepaksi, ujian kekuatan regangan Brazil dan indeks kekuatan beban titik. Analisis statistik hasil ujian pada aras keyakinan 95 peratus memaparkan bahawa purata kekuatan mampatan granit segar dan terluluhawa sedikit ialah 113.6±7.0 dan 68.9±3.6 MPa, sementara nilai bagi syis segar dan terluluhawa sedikit pula ialah 137.3±9.2 dan 84.8±5.1 MPa. Seterusnya, nilai purata kekuatan regangan granit segar dan terluluhawa sedikit ialah 8.8±0.4 dan 5.3±0.1 MPa manakala nilai purata syis segar dan terluluhawa ialah 17.1±0.9 dan 10.5±0.4 MPa. Purata kekuatan beban titik granit segar dan terluluhawa sedikit ialah 9.4±0.30 dan 5.6±0.10 MPa manakala nilai syis segar dan terluluhawa sedikit ialah 10.9±0.42 dan 7.0±0.10 MPa. Hasil kajian menunjukkan bahawa kekuatan geomekanik bahan batuan segar menyusut lebih kurang 1/3 setelah tahap perluluhawaan bahan batuan tersebut menurun ke peringkat luluhawa sedikit.

Kata kunci: Granit; ujian indeks kekuatan beban titik; ujian kekuatan mampatan sepaksi; ujian kekuatan regangan Brazil; syis

ABSTRACT

The geomechanical strength of rock materials plays a significant role in influencing the stability of structures like cut slopes and excavation of opening in rock mass. The strength characteristics of rock mass where these structures are constructed are influenced by both material characteristics and the condition of weathering. This paper presents the results of a systematic research to quantify the mechanical characteristics of fresh as well as slightly weathered granites and schists of Peninsular Malaysia. A total of 1,013 geomechanical strength tests were conducted for both these lithologies for fresh as well as slightly weathered rock materials employing the uniaxial compressive strength test, Brazilian tensile strength as well as the point load strength index test. Statistical analysis of the results at 95 percent confidence level showed that the means of compressive strength for fresh and slightly weathered granites were 113.6±7.0 and 68.9±3.6 MPa while the respective values for fresh and slightly weathered schists were 137.3±9.2 and 84.8±5.1 MPa. Subsequently, the respective mean values of tensile strength for fresh and slightly weathered granites were 8.8±0.4 and 5.3±0.1 MPa while the values of mean for fresh and slightly weathered schists were 17.1±0.9 and 10.5±0.4 MPa, respectively. For the point load strength, the means for fresh and slightly weathered granites were 9.4±0.30 and 5.6±0.10 MPa whereas the respective values for fresh and slightly weathered schists were 10.9±0.42 and 7.0±0.10 MPa. The results of this research revealed that the geomechanical strengths of fresh rock material deteriorated by approximately 1/3 when weathering grade of the rock material reduces to slightly weathered rock materials.

Keywords: Brazilian tensile strength test; granite; point load strength index test; schist; uniaxial compressive strength test

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*Corresponding author; email: gdsbgoh@gmail.com