Numerical Modelling of Slope Stability and Transient Seepage Analysis: Jalan Puncak Borneo Road Case Study

A slope failure event in 2015 at KM 6+500 of Jalan Puncak Borneo in Padawan, Kuching was modelled using Seep/w and Slope/w software of commercial geotechnical programme GEOSTUDIO. The failure was occurred after a prolonged three days of heavy rain. The state road which connected the villagers from Puncak Borneo was cut off and caused traffic congestion.  In this study, the slope stability was evaluated based on finite element and limit equilibrium method by considering the transient seepage analysis due to rainfall infiltration.  The slope failure was modelled based on ground investigation report and published data to replicate the field condition.  A hyetograph was plotted using daily rainfall data and cumulative rainfall depth was determined to obtain the total rainfall during the wet monsoon. As a result of numerical analyses, the factor of safety was observed to fluctuate with time of infiltration. Based on this case study, the factor of safety or FOS reduced with time and a perched water table also has been observed developed just below the pavement.  However, the factor of safety calculated from Slope/w could not replicate the actual failure.  Nevertheless, it can be observed that factor of safety had decreased with respect to infiltration in the analyses.  The steady state condition provided FOS 1.33 and had reduced to 1.27 after 110 days of rainfall event.  Thus, the analyses of this current study have illustrated that the transient analysis is essential to model the seepage behaviour and infiltration event that caused slope failure along Sarawak’s roads

Numerical Modelling of Slope Stability and Transient Seepage Analysis: Jalan Puncak Borneo Road Case Study

A slope failure event in 2015 at KM 6+500 of Jalan Puncak Borneo in Padawan, Kuching was modelled using Seep/w and Slope/w software of commercial geotechnical programme GEOSTUDIO. The failure was occurred after a prolonged three days of heavy rain. The state road which connected the villagers from Puncak Borneo was cut off and caused traffic congestion.  In this study, the slope stability was evaluated based on finite element and limit equilibrium method by considering the transient seepage analysis due to rainfall infiltration.  The slope failure was modelled based on ground investigation report and published data to replicate the field condition.  A hyetograph was plotted using daily rainfall data and cumulative rainfall depth was determined to obtain the total rainfall during the wet monsoon. As a result of numerical analyses, the factor of safety was observed to fluctuate with time of infiltration. Based on this case study, the factor of safety or FOS reduced with time and a perched water table also has been observed developed just below the pavement.  However, the factor of safety calculated from Slope/w could not replicate the actual failure.  Nevertheless, it can be observed that factor of safety had decreased with respect to infiltration in the analyses.  The steady state condition provided FOS 1.33 and had reduced to 1.27 after 110 days of rainfall event.  Thus, the analyses of this current study have illustrated that the transient analysis is essential to model the seepage behaviour and infiltration event that caused slope failure along Sarawak’s roads

Structural dynamic response of an unreinforced masonry house using non-destructive forced vibration

The results of non-destructive forced vibration tests on a small-scale unreinforced masonry house with a flexible timber diaphragm are presented. The primary purpose of this study was to investigate the dynamic responses between the as-built and retrofitted structures. This includes assessment of diaphragm response, wall-diaphragm connection details, in-plane wall response, out-of-plane wall response, and the response of wall corners. The test protocols were designed to investigate two types of retrofit techniques consisting of a plywood-retrofit on the diaphragm, and a connection-retrofit between the wall and diaphragm. From the results, one can see that the natural frequency and mode shapes of the first translational mode were affected. The force transfer mechanism of the as-built structure was significantly improved after applying both retrofits whereas each technique shows distinctive enhancements on the structure overall response

CHEMICAL STABILIZATION OF SARAWAK CLAY SOIL WITH CLASS F FLY ASH

Chemical stabilization of Sarawak clay soil was studied via Fly Ash (FA) due to their potential benefit. FA is a by-product produced from thermal power plant and disposal of FA causing an environmental hazard. Investigation on the feasibility of FA as a potential stabilizer to stabilize the Sarawak clay soils was performed via Unconfined Compression Strength (UCS) and Triaxial Consolidated Isotropic Undrained (CIU). From the compaction results, the Maximum Dry Density (MDD) and the Optimum Moisture Content (OMC) for all mixtures increased and decreased respectively compared to natural soil. Based on the UCS test, the addition of 20% FA and 40% FA achieved a significant improvement in compressive strength and recommended as optimum stabilizer amount. The plasticity index and linear shrinkage for the FA stabilized soil decreased compared to the natural soil. The triaxial test was performed for the optimum amount of stabilizer and obtained significant improvement in effective cohesion and effective internal friction angle compared to natural soil. The deviator stress for FA stabilized soil also increased compared to the natural soil corresponding to the confining pressure. The morphology of stabilized soil shows the existence of cementitious product, which contributed to strength increased as observed via Scanning Electron Microscopy (SEM)

Graphene array antenna for 5G applications

Fifth generation (5G) needs to provide better coverage than the previous generation. However, high frequency and millimeter wave experience penetration loss, propagation loss and even more loss in energy for long distance. Hence, a graphene array antenna is proposed for high gain to cover a long distance communications since array antenna enables in providing more directive beams. The investigation is conducted on three types of substrates with gain achieved is more than 7 dBi. The gain obtained is good since it is comparable with other studies. In addition, these antennas consume small numbers of elements to achieve high gain