Bulletin of the Geological Society of Malaysia, Volume 69, May 2020, pp. 39 – 51

Integrasi pemetaan lapangan, tafsiran lineamen dan survei tomografi keberintangan geoelektrik dalam pencirian jasad batuan granit terlindung shotcrete

Hamzah Hussin^1,2,*, Mohd Hariri Arifin¹, Tajul Anuar Jamaluddin¹, Muhammad Fahmi Abdul Ghani¹, Nadzari Ismail³, Abdul Manan Abdullah⁴

1Pusat Pengajian Sains Bumi & Alam Sekitar, Fakulti Sains & Teknologi,
Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia
2 Jabatan Geosains, Fakulti Sains Bumi, Universiti Malaysia Kelantan, 17600 Jeli, Kelantan, Malaysia
3 TNB Research Sdn. Bhd., No 1, Kawasan Institusi Penyelidikan, Jalan Ayer Hitam, 43000 Kajang, Selangor, Malaysia
4 Geo Technology Resources Sdn Bhd, 31-1, Jalan Mawar 5b, Taman Mawar, 43900 Sepang, Selangor, Malaysia
* Corresponding author email address: hamzah.h@umk.edu.my

Abstrak: Pencirian jasad batuan penting bagi mengenalpasti keadaan jasad batuan terutamanya jika melibatkan binaan struktur utama seperti terowong. Pencirian jasad batuan boleh dilakukan samada sebelum, semasa atau selepas pembinaan. Dalam kajian kes ini, pencirian jasad batuan dilakukan selepas terowong siap dibina dan telah aktif beroperasi menghampiri 20 tahun. Pencirian tidak dapat dilakukan secara cerapan terus dilapangan kerana separuh daripada jasad batuan sepanjang terowong telah ditutupi oleh lapisan shotcrete. Pendekatan intergasi melibatkan tiga kaedah iaitu pemetaan lapangan, tafsiran imej satelit dan survei tomografi keberintangan geolektrik telah digunakan untuk mengatasi permasalahan ini. Tafsiran imej satelit menekankan kepada surihan struktur lineamen negatif manakala pemetaan lapangan menekankan kepada lokasi resapan air bawah tanah dan struktur tektonik major seperti sesar, kekar dan zon ricih. Survei tomogafi keberintangan geoelektrik dijalankan pada bahagian dinding terowong menggunakan sistem ABEM SAS 4000 dan susunatur dwikutub-dwikutub. Data mentah diproses menggunakan perisian Res2DINV. Analisis data menunjukkan kehadiran tiga nilai keberintangan bahan yang berbeza iaitu berkeberintangan tinggi (> 1500 Ω.m), sederhana (100-500 Ω.m) dan rendah (< 25 Ω.m). Dapatan daripada pemetaan lapangan dan tafsiran lineamen digunakan dalam tafsiran keratan rentas pseudo. Ketiga-tiga nilai ini ditafsirkan sebagai zon tinggi kandungan air (berkeberintangan rendah), jasad batuan terkesan lineamen dan terkekar kuat (berkeberintangan sederhana) dan batuan granit kurang terkekar (berkeberintangan tinggi).

Kata kunci: Pemetaan lapangan; pencirian jasad batuan; survei keberintangan tomografi keberintangan geoelektrik; tafsiran imej satelit

Integration of field mapping, lineament interpretation and electrical resistivity tomography survey to characterize granitic rock mass lining by shotcrete

Abstract: Rock mass characterization is important to identify the condition of rock especially in major infrastructure like a tunnel. Rock mass characterization can be done either before, during or after construction completed. In this case study, this characterization was done after almost 20 years of tunnel operation. Characterization could not be done directly to the field as half of the rock mass along tunnel was covered by shotcrete layer. To overcome this problem, three integration methods which are field mapping, satellite image interpretation and geoelectrical tomography resistivity survey been approached. Satellite image interpretation is to emphasise negative lineament structure tracing while field mapping is to emphasis the location of groundwater intrusion and major tectonic structures like fault, joint and shear zone. Geoelectrical tomography resistivity survey was conducted using ABEM SAS 400 system and dipole-dipole array while raw data were processed using Res2DINV software. Data analysis showed three difference resistivity values which are high resistivity (> 1500 Ω.m), moderate (100-500 Ω.m) and low (<25 Ω.m). Findings from field mapping and lineament interpretation were used to interpret pseudosection. All three resistivity values were interpreted as high water content zone (low resistivity), lineament effected and highly fractured granitic rock mass (moderate resistivity) and low fractured granitic rock (high resistivity).

Keywords: Electrical resistivity tomography survey; field mapping; rock mass characterization; satellite image interpretation

DOI: https://doi.org/10.7186/bgsm69202004