Conference Paper

THE APPLICATION OF SEISMIC REFRACTION SURVEY FOR SUBSURFACE PROFILE INVESTIGATION

Conference: International Conference in Building, Science and Engineering (ICON BSE'09)

ABSTRACT The information of the subsurface profile is important to be use in civil engineering design and construction. The problem such as structure defect and failure may arise if the information gathered from the site investigation works was unreliable. This study determines the solution approaches for subsurface profile determination by using seismic refraction survey and borehole exploration method. From past experienced, borehole exploration which consider as a conventional method was a very popular used in site investigation compared to other method. The subsurface profile data used from the conventional method for design and construction sometimes creates cases of structure defect and failure due to lack of information about subsurface profile. This situation proves that the site investigation works by borehole exploration should be supported with other method due to its limitation and the uncertainties of
soil. This study is carried out for investigating other method which reliable to be considered in studying subsurface profile. Hence, this study introduced the seismic refraction survey which used the seismic waves generated by one of several types of energy sources and detected by arrays of sensitive devices called geophones for subsurface profile data compared with borehole exploration. Those methods are used to determine the information of the subsurface profile such as depth layers, type of soil/rock and the groundwater table. It was found that the seismic refraction survey produce the results which almost similar to the borehole method. This proved that the seismic refraction survey was a good technique to be applied together with a conventional method in civil engineering site investigation in order to produce much reliable information.

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    ABSTRACT: The subsurface profile investigation plays a major role during the failure of many civil engineering structures. The problem of structure defect and failure can unpredictably occur and this creates a challenge to an expert to investigate and solves the situation. This study determines the solution approaches for subsurface profile forensic study by geoelectrical method. It was difficult to carry out a forensic study especially to investigate the problem involving the underground profile such as the stability of foundation and slope. The problems arise because of the difficulty to select and apply the most suitable equipment that can produce clear information since the nature of underground profile which has lots of uncertainties. This study was carried out to assist the civil engineering forensic team for solving their investigation especially to contribute the subsurface profile information regarding the causes of the failure. Hence, the geoelectrical method which used the direct current generated by energy source and detected by arrays of sensitive devices for subsurface profile investigation was introduced. The geoelectrical method is one of the geophysical methods used for mapping the underground profile such as detecting the boulder, groundwater, soil and rock. It was found that the geoelectrical method can detect and identify the causes of the failure in our site studied at Bangi and Bentong such as detecting the presence of weak layer saturated with water that cause the structure to failed. The image produced by the survey can give an expert some of the valuable information for solving their forensic job and it was a good technique to be applied together with a conventional method in order to produce a reliable information and answer.
    Malaysian Technical Universities Conference on Engineering and Technology; 01/2010
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    ABSTRACT: Surface geophysical method was used in studying the effect of natural disaster impact and subsurface physical changes located in an active geohazard zone at the Kundasang area in Sabah, Malaysia. The natural disaster impact was a previous surface and subsurface ground damage caused by a landslides activity, and the consequent civil engineering infrastructure failure. 2D seismic refraction tomography (2DSRT) was used in evaluating the continuous subsurface ground damage with particular reference to geomaterials and landslide features based on compressional wave (Primary velocity, vp) results. A total of four spread lines were conducted in two different zones (Northeast and Southwest zone) in Kundasang Secondary School (SMK Kundasang). Primary velocity data was acquired and recorded using ABEM Terraloc MK6 seismograph with the seismic wave being triggered by an impact and detected by arrays of sensitive devices called geophones. 2D seismic refraction primary velocity results representing subsurface profile for each survey line were calculated to determine time and depth of the subsurface profile investigated based on linear and delay time analysis supplied by Optim software package and supported by previous borehole data. The seismic refraction method identified three main layers of geomaterials which contained a subsurface landslides anomaly within the layers. The results consist of top soil/residual soil (330 600 m/s) 0 6 m, weathered zone with a mixture of soil, boulder and rock fractured (500 1900 m/s) 2 25 m and fresh rock/bedrock (> 2300 m/s) from 8 m depth. The landslides geometry was determined inconsistently within the survey line from 3 25 m (thickness), 57 and 75 m (width) and 100 m and more (length) with a primary velocity of 700 1800 m/s. The seismic refraction profiles obtained also revealed that the landslide occurrence extends from the southeast zone and continuously heading towards the northeast zone. A good matching seismic refraction results was obtained and calibrated using borehole results which shows that this technique was appropriate to be applied in near-surface landslide assessment which can further substantiates and compliments borehole data and others physical mapping data rapidly in a lower cost. Furthermore, this geophysical method adopts a surface technique that can minimise the disruption and damage to the site thus preserving a sustainable environment during the site investigation data acquisition stages.
    Procedia Engineering. 10/2012; 50:516 – 531.