Nordiana Mohd Muztaza

Integration of Magnetic and Geotechnical methods for Shallow Subsurface Soil Characterization at Sungai Batu, Kedah, Malaysia

Magnetic and geotechnical methods were used for shallow subsurface soil characterization at Sungai Batu, Kedah, (Malaysia). Ground magnetic data were collected along a survey line of length 160 m long at 2 m constant station spacing, while soil drilling using hand auger was conducted at 21 m on the survey line using 0.2 m sampling interval drilled to a depth of 5 m. Result from the processed magnetic profile data shows distribution of magnetic residuals in the range of -4.55 to 1.61 nT, with magnetic low (-4.55 nT to -0.058 nT) and were identified at distances 4 m, 10 to 16 m, 20 to 26 m, 58 m, 82 m, 104 to 106 m, 118 m, and 124 to 140 m. The magnetic lows are attributes of sediments. The result from the soil drilling shows sticky samples with variable sizes, greyish to brownish / reddish in colour, and some of the samples show the presence of shiny and black spots. The characteristics of the samples suggest the soil as a by-product of completely weathered rock; weak with high water content and classified as Grade V soil. The study concludes; integration of geophysical and geotechnical methods aided in characterizing the subsurface soil at Sungai Batu. The result was correlated with previous studies and confirms the importance of integrated approach in minimising ambiguity in interpretation.

Correlation of Geophysical and Geotechnical Methods for Sediment Mapping in Sungai Batu, Kedah

Exploration geophysics is widely used to map the subsurface characteristics of a region, to understand the underlying rock structures and spatial distribution of rock units. 2-D resistivity and seismic refraction methods were conducted in Sungai Batu locality with objective to identify and map the sediment deposit with correlation of borehole record. 2-D resistivity data was acquire using ABEM SAS4000 system with Pole-dipole array and 2.5 m minimum electrode spacing while for seismic refraction ABEM MK8 seismograph was used to record the seismic data and 5 kg sledgehammer used as a seismic source with geophones interval of 5 m spacing. The inversion model of 2-D resistivity result shows that, the resistivity values 500 Ωm as the hard layer for this study area. The seismic result indicates that the velocity values 3600 m/s interpreted as the hard layer in this locality.

Determination of slope failure using 2-D resistivity method

Landslides and slope failure may give negative economic effects including the cost to repair structures, loss of property value and medical costs in the event of injury. To avoid landslide, slope failure and disturbance of the ecosystem, good and detailed planning must be done when developing hilly area. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. The study on landslide and slope failure was conducted at Site A and Site B, Selangor using 2-D resistivity method. The implications of the anticipated ground conditions as well as the field observation of the actual conditions are discussed. Nine 2-D resistivity survey lines were conducted in Site A and six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed in Site B. The data were processed using Res2Dinv and Surfer10 software to evaluate the subsurface characteristics. 2-D resistivity results from...

Imaging geological contact utilizing 2D resistivity method for light rail transit (LRT) track alignment

The purpose of this study was to locate the geological contact using 2D resistivity method for Light Rail Transit (LRT) track alignment. The resistivity method was conducted on eight survey lines with the length of line 1 was 600m. The length of line 2, 3, 4, 5, 6, and 7 were 200m each while line 8 is 115m. All the survey used minimum electrode spacing of 5m and using Pole-dipole array with minimum current is 2mA and maximum was 20mA. The result obtained from the pseudosection showed that the area generally divided into three main zones, fill materials/residual soil with a resistivity value of 2000 Ωm. Three fractured zones were detected along line L1 and a lot of boulders were detected at L1, L3, L4, L5 and L6. The geological contact was between the residual soil and granite bedrock.

Identification Of Rippability And Bedrock Depth Using Seismic Refraction

Spatial variability of the bedrock with reference to the ground surface is vital for many applications in geotechnical engineering to decide the type of foundation of a structure. A study was done within the development area of Mutiara Damansara utilising the seismic refraction method using ABEM MK8 24 channel seismograph. The geological features of the subsurface were investigated and velocities, depth to the underlying layers were determined. The seismic velocities were correlated with rippability characteristics and borehole records. Seismic sections generally show a three layer case. The first layer with velocity 400–600 m/s predominantly consists of soil mix with gravel. The second layer with velocity 1600–2000 m/s is suggested to be saturated and weathered area. Both layers forms an overburden and generally rippable. The third layer represents granite bedrock with average depth and velocity 10–30 m and >3000 m/s respectively and it is non‐rippable. Steep slope on the bedrock are probably the results...

Testing Of Resistivity Imaging Method with Different Protocols to Detect Void Using Miniature Model

Sinkholes, cavities, boulders and faults in rock and soil could lead to major engineering and environmental problems. Resistivity variation is an important property in shallow subsurface investigation. Resistivity values of rock and soil are severely affected by pore connectivity and fluid type. Resistivity method is one of the geophysical surveys employed to map the subsurface structures. Resistivity data was collected using three different arrays (Wenner, Wenner‐Schlumberger and Pole‐dipole) on the homogenous ground with 5 cm electrodes spacing. Subsequently, two identical square holes (20 cm×7 cm×30 cm) were made 10 cm below the ground surface and 20 cm apart. The resistivity data was collected again using the three different arrays across the two holes. The result for the homogenous ground shows a low resistivity value, while the homogenous ground with holes show high resistivity value around the holes. The results of the three arrays are then compared. The Pole‐dipole array produced the best image of...