Sains Malaysiana 46(11)(2017): 2187-2193

http://dx.doi.org/10.17576/jsm-2017-4611-20

 

Laboratory Study of Acoustic Velocity in Different Types of Rocks at Seismic Frequency Band

(Kajian Makmal Halaju Akustik dalam Pelbagai Jenis Batuan pada Jalur Frekuensi Seismos)

 

 

YUNLAN HE¹,²*,SUPING PENG², WENFENG DU², XIAOMING TANG² & ZENG HU²

 

¹State Key Laboratory of Water Resource Protection and Utilization in Coal Mining, Beijing 100011, China

²State Key Laboratory of Coal Resources and Safety Mining, China University of Mining & Technology (Beijing), Beijing 100083, China

 

Diserahkan: 22 Januari 2017/Diterima: 30 Mei 2017

 

ABSTRACT

In order to understand the characteristics of acoustic wave propagation in rocks within seismic frequency band (<100 Hz), the velocities of longitudinal and transverse waves of four different types of rocks were tested using low-frequency stress-strain method by means of the physical testing system of rock at low frequency and the experimental data of acoustic velocities of four different types of rocks at this frequency band were obtained. The experimental results showed that the acoustic velocities of four different types of rocks increased with the increase of temperature and pressure within the temperature and pressure ranges set by the experiment. The acoustic velocity of fine sandstone at 50% water saturation was smaller than that of dry sample. The acoustic velocities of four different types of rocks were different and the velocities of longitudinal waves of gritstone, fine sandstone, argillaceous siltstone and mudstone increased in turn under similar conditions and were smaller than those at ultrasonic frequency. Few of existing studies focus on the acoustic velocity at seismic frequency band, thus, further understanding of the acoustic characteristics at this seismic frequency band still requires more experimental data.

 

Keywords: Acoustic velocity; pressure; seismic frequency band; temperature

 

ABSTRAK

Untuk memahami ciri penyebaran gelombang akustik dalam jalur frekuensi seismos (< 100 Hz) batuan, halaju gelombang membujur dan melintang empat jenis batuan berbeza telah diuji menggunakan kaedah frekuensi rendah strain-tegasan melalui sistem ujian fizikal batuan pada frekuensi rendah dan data uji kaji halaju akustik daripada empat jenis batuan pada jalur frekuensi ini diperoleh. Keputusan uji kaji menunjukkan bahawa halaju akustik daripada empat jenis batuan meningkat dengan peningkatan suhu dan tekanan dalam julat suhu dan tekanan yang ditetapkan oleh uji kaji ini. Halaju akustik batu pasir halus pada 50% air tepu adalah lebih kecil berbanding dengan sampel kering. Halaju akustik daripada empat jenis batuan berbeza dan halaju daripada gelombang membujur batu grit, batu pasir halus, batu lodak argil dan batu lumpur meningkat pada keadaan yang serupa tetapi lebih kecil berbanding dengan kekerapan ultrasonik. Beberapa kajian sedia ada memberi tumpuan kepada kelajuan akustik pada jalur frekuensi seismos, oleh itu, pemahaman lanjut terhadap ciri akustik pada jalur frekuensi seismos ini masih memerlukan lebih data uji kaji.

 

Kata kunci: Halaju akustik; jalur frekuensi seismos; suhu; tekanan

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