No abstract

The pre-construction works include the geotechnical investigation which comprises the surface and subsurface exploration. Sub-surface exploration often causes several difficulties such as high cost, time consuming, localized investigation and intrusive. Furthermore, investigation on soft soil such as peat often raises several additional problems such as high risk of sample disturbance, difficult access for heavy equipment and inconsistent data due to the heterogeneity of peat. The advancement of geophysical method such as Electrical Resistivity Tomography (ERT) allows the determination of soil profile in time-efficient manner, economic, larger volume of investigation and non-intrusive. This study focused on the determination of soil profile, particularly peat layer using ERT method with complement from peat sampler data. The study was conducted at Parit Nipah, Johor. The results revealed a high accuracy profile delineated by the ERT method with only less than 8% percentage of error as compared to peat sampler profile. The comparison between Schlumberger and Wenner array showed that; the Schlumberger showed superior depth of penetration, with almost 3 times deeper penetration relative to Wenner. The Schlumberger array is also able to delineate lateral variation within the peat layer. Finally, the resistivity value of peat obtained ranged from 100.8 to 139.5 ohm.m with both arrays having consistent results.

Geotechnical design commonly requires that the in-situ stiffness, strength and permeability of the ground be obtained. Laboratory based investigation often related with risk of sample disturbance and difficulties to replicate the in-situ stress condition which results in overestimation or underestimation. Application of geophysical methods in geotechnical investigation previously was limited to targeting and dimensioning sub-surface features due to lack of resolution. However, rapid developments of geophysical methods result in the application of these methods in providing geotechnical design parameters. Multichannel analysis of surface waves (MASW) and seismic refraction were among the geophysical methods capable of obtaining stiffness parameters including the maximum shear modulus (Gmax) and maximum elastic modulus (Emax). The study revealed the efficiency of these methods to measure the small strain stiffness of peat soil with high accuracy as the results obtained were found to be similar to those obtained by previous researchers. Overall, the Gmax and Emax values of peat soil obtained range from 0.49 to 1.72 MPa and 1.46 to 5.15 MPa respectively. The Gmax and Emax values obtained shows significant increase with depth governed primarily by the effective stress. Other parameters such as degree of decomposition and peat thickness also shows potential influence on the Gmax and Emax values obtained.

The effect of rare earth metal erbium (Er) modification on the microstructure and mechanical properties of aluminium alloys (A380) were investigated using Optical Microscope (OM), Scanning Electronic Microscope (SEM) attached with Electron Dispersive Scanning (EDS), Vicker’s hardness test and Ultimate Tensile Test (UTS). The results show that the addition of Er reduces the size of the silicon particle and improve mechanical properties of the aluminium alloy. In addition, by adding 0.1 wt. % of Er, the mean area (μm2) and aspect ratio value decreased. The coarse plate like existed in the unmodified alloy transformed into fine particle and short rod. The mechanical properties were investigated by using tensile test and Vicker’s hardness test. The ultimate tensile strength test shows that the tensile and the elongation increased 1.32 % and 9.1 % with 0.1 wt. % Er content of the aluminium alloys, respectively. The hardness improved from the addition of 0.1% Er aluminium A380 alloy.

The degree of composition for peat soil in geotechnical engineering may affected the shear strength of the peat soil based on their types (sapric, hemic and fabric). The strength was affected by many factors such as its origin, water content, organic matter and arrangement of peat fibric. The aims of this paper was to investigate the influence of segregation peat sizes and preconsolidation pressure on the effective shear strength properties of reconstituted peat 1.000 mm (<RS1.00) and reconstituted peat 2.360 RS2.36). All the reconstituted peat samples were segregated through passing opening sieve size 1.00 mm and 2.36 mm with the aid of water to obtain homogeneous reconstituted peat slurry and were preconsolidated with 50 kPa, 80 kPa and 100 kPa pressure to obtain samples for triaxial tests. The Triaxial Consolidated Undrained Test was selected to test the shear strength properties of the reconstituted peat samples by using confining pressure 25 kPa, 50 kPa and 100 kPa. Both of the effective shear strength properties result such as cohesion and angle of friction obtained recorded <RS2.36 has higher strength than <RS1.00. The main factors that contribute to the differences shear strength value between two size reconstituted peats were segregation of peat size which affected by peat size (fiber size) and also pre-consolidation pressure applied which reduced the voids, water content and also improved the stiffness and strength of the specimen. All specimen and testing was conducted at RECESS, UTHM.