Sains Malaysiana 38(5)(2009): 645–653

Survei Pengimejan Elektrik dan Georadar dalam Kajian Tanah Runtuh

Taman Hill View, Ampang, Selangor

(Survey of Electrical Imaging and Georadar on Landslides Investigation at Taman Hillview, Ampang, Selangor)

Umar Hamzah*, Nurul Fairuz Diyana Bahrudin

Pusat Pengajian Sains Sekitaran dan Sumber Alam

Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E., Malaysia

Mohd. Azmi Ismail & Amry Amin Abbas

Agensi Nuklear Malaysia Bangi

43000 Kajang, Selangor D.E.,  Malaysia

Diserahkan: 21 Ogos 2007 / Diterima: 5 Mac 2009

ABSTRAK

Satu kajian menggunakan kaedah pengimejan elektrik dan georadar telah dijalankan di Taman Hill View, Ampang, Selangor yang telah mengalami kejadian tanah runtuh. Gelinciran ini adalah susulan daripada tiga kejadian tanah runtuh yang berlaku di sekitar kawasan Hulu Klang, Selangor terutamanya di sekitar Bukit Antarabangsa. Tujuan kajian adalah untuk mengenal pasti ciri-ciri bahan runtuhan dan kedalaman batuan dasar melalui survei pengimejan elektrik serta pencirian kawasan rekahan, retakan dan zon lemah melalui survei georadar. Survei dilakukan berhampiran dengan lubang-lubang gerudi di sepanjang beberapa teres potongan cerun. Jarak elektrod yang digunakan ialah 2.0-2.5 m. Berdasarkan jumlah elektrod yang digunakan ialah 41, ini bermakna jarak maksimum elektrod arus ialah 80-100 m dan kedalaman maksimum yang diukur ialah 20 hingga 25 m. Kaedah Radar Penusukan Bumi pula menggunakan gelombang elektromagnet berfrekuensi 100 MHz. Model keberintangan elektrik menunjukkan profil luluhawa batuan granit dengan julat keberintangan antara 2 hingga 7000 Ωm. Pola atau zon keberintangan rendah yang berada di antara zon keberintangan tinggi ditafsirkan mewakili rekahan dan sesar dalam batuan granit yang mengalami luluhawa dan berkemungkinan berisi air pada kedalaman 4 hingga 5 m. Keratan rentas keberintangan menunjukkan kedudukan kawasan rekahan, retakan dan zon lemah tersebut. Keratan rentas yang diperolehi hasil survei radar penusukan bumi juga membuktikan dengan lebih jelas akan kehadiran sesar dan retakan yang terdapat dalam zon luluhawa batuan granit di kawasan kajian melalui kewujudan anjakan-anjakan pemantul dan ciri-ciri pemantul yang terputus.

Kata kunci: Retakan; survei keberintangan elektrik; survei radar penusukan bumi; tanah runtuh; sesar; zon luluhawa

ABSTRACT

Electrical resistivity and Ground Penetrating Radar (GPR) surveys were carried out at Taman Hill View, Ampang, Selangor landslide area. This landslide site was a part of three similar landslides which occurred at Bukit Antarabangsa, Hulu Klang, Selangor. The landslide had occurred along the road to Bukit Antarabangsa and Athenaeum Tower. The objectives of these studies were to characterise the sliding material and to determine the depth of bedrock below the sliding surface using the electrical resistivity imaging technique as well as to recognise the fractured or weak zone using the GPR technique. The spacing between electrodes used in the survey was 2 to 2.5 m and the survey lines were chosen close to the borehole locations. With a total of 41 electrodes and spacing between each electrode of 2 to 2.5 m, the maximum current electrode spacing in this survey would be between 80-100 m resulting in the deepest subsurface depth investigated approximately at 20 to 25 m. A 100 MHz electromagnetic wave was used in the Ground Penetration Radar survey. The resistivity imaging result showed the weathered granite profile with resistivity value ranging from 2 to 7000 Ωm. The patterns also show that this area had a lot of fractured or weak zones up to a depth of 4 to 5 m based on the occurrence of low resistivities zones in between the high resistivities. These highly fractured and faulted zones also appeared in the GPR sections as shown by the presence of shifted reflectors and layer discontinuity.

Keywords: Electrical resistivity survey; ground penetrating radar survey; landslide; fault; cracks; weathered zone

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*Pengarang untuk surat-menyurat; email: umar@ukm.my