A meaningful correlation between shallow seismic refraction data to borehole data in site investigation work

Abstract

In site investigation work the subsurface characteristic is mainly determined from boreholes data such as the bore log, standard penetration test and other suitable test. Surface geophysical survey including seismic refraction has been routinely used to compliment the borehole data. In many small scale site investigation boreholes are made mainly using the wash boring method and are normally very shallow. The standard penetration test value N = 50 is used to end the borehole and it occurs normally within the weathered zone or above the bedrock surface. The seismic work determines the depth and characteristic of the bedrock as well as the strata above the bedrock. The seismic refraction data is compared to the boring data and often used to extrapolate the subsurface condition between the boreholes. Correlation of seismic refraction data to wash boring data is often difficult because the wash boring bore log description is mainly grain sized based and not lithological based. Comparison to both the bore log and the standard penetration test values allows a better correlation. In addition, at the shallower level the Mackintosh probe test value and the water table has been used. The two sites studied show that comparison of the seismic refraction data to an integrated data gives a more meaningful and useful correlation. Abstrak: Dalam kerja penyiasatan tapak ciri ciri subpermukaan biasanya di tentukan dari data lubang bor termasuk log lubang bor, ujian tusukan piawai atau dari ujian ujian lain yang bersesuaian. Survei geofizik permukaan termasuk seismos biasan selalu di gunakan bersama dengan lubang bor. Dalam penyiasatan tapak skala kecil pengrudian biasanya mengunakan kaedah pemboran basuhan dan hujung lubang bor biasanya cetek sahaja. Nilai ujian tusukan piawai N = 50 digunakan mengakhiri pemboran dan biasanya ia berada di zon luluhawa dan di atas paras batudasar. Kerja seismos biasan menentukan kedalaman batudasar dan ciri strata di dari batudasar. Data seismos di bandingkan kapada data lubang bor dan biasanya di gunakan bagi menganggarkan ciri subpermukaan antara lubang bor. Pengkaitan antara data seismos kapada data lubang bor dari pemboran basuhan sahaja biasanya sukar kerana penerangan log lubang bor dari kaedah ini adalah berdasarkan kapada saiz butiran dan bukan litologi. Perbandingan data seismos kapada data lubang bor bersama nilai ujian tusukan piawai memberikan perkaitan yang lebih baik. Pada kedalaman cetek perbandingan juga di buat kapada uji prob Mackintosh dan aras air tanah. Kajian di dua tapak menunjukan perbandingan data seismos kepada data bersepadu lubang bor dapat memberikan perhubungan yang lebih bermakna dan berguna.