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

Monitoring strain development of soil slope using distributed optical fibre sensor

Rainfall infiltration is well-known as one of the important factors that lead to slope failure in tropical areas such Malaysia because it's significant fluctuation of pore water pressure due to monsoon seasons. In this paper, a distributed sensing optical fibre system named Brillouin Optical Time Domain Analysis (BOTDA) is used to monitor the strain development of a laboratory soil slope model. The aim of study is to determine the plane failure of a residual soil slope under rainfall infiltration and subsequent loading impact using BOTDA technology. A soil slope model was constructed from Malaysian residual soil slope and tested under various rainfall infiltration patterns and sequential loadings. A continuous ribbon optical fibre has been directly embedded in the soil slope to measure the soil strain. The paper only presented on soil strain response due to rainfall infiltration and relations to the pore pressure development within the finite slope. From the experiments, it has been observed that the optical fibre has been able to capture soil strain during infiltration which proven the sensitivity of optical fibre to measure soil strain. The maximum strain observed was about 850 microstrain (μϵ) which occurred at the third layer of slope height (L1) at 8-hour of infiltration. After 24-hours of infiltration, the strain was observed to be constant for all layers; Layer 1 (L1) = 302 μϵ, Layer 2 = 210 μϵ and Layer 3 (L3) = 190 μϵ in which the whole sample was clearly seen in a fully saturated condition and the negative pore pressure has remained constant throughout the depth

Landslide Susceptibility in Relation to Correlation of Groundwater Development and Ground Condition

Rainfall is inevitably one of the main factors that trigger landslides. However, not much study has been conducted on the impact of groundwater rise on slope stability. Thus, this study is intended to focus on the rise of the groundwater level from the bottom of the slope which would lead to landslides due to pore pressure development by eliminating other landslide-triggering factors (i.e., infiltration and surface runoff). Saturated sand was used for slope modeling, and sand densities of 1523 kg/m3, 1562 kg/m3, and 1592 kg/m3 were tested with a constant slope angle of 45°. Another set of experiments was also performed on slopes having angles of 25°, 45°, and 60° and with a maintained density of sand at 1562 kg/m3. Through observation, failure was initiated first at the toe of the slope before minor and major slips or total collapse occurs. Dimensions of slip surfaces were measured and included in SLOPE/W for the computation of the safety factor. In conclusion, safety factors are found to be higher in denser soil and in the lowest slope angle. However, faster occurrence of collapse in denser soil was identified and could be contributed by the faster pore water pressure development

Trend and status of air quality at three different monitoring stations in the Klang Valley, Malaysia

Over the last decades, the development of the Klang Valley (Malaysia), as an urban commercial and industrial area, has elevated the risk of atmospheric pollutions. There are several significant sources of air pollutants which vary depending on the background of the location they originate from. The aim of this study is to determine the trend and status of air quality and their correlation with the meteorological factors at different air quality monitoring stations in the Klang Valley. The data of five major air pollutants (PM10, CO, SO2, O3, NO2) were recorded at the Alam Sekitar Sdn Bhd (ASMA) monitoring stations in the Klang Valley, namely Petaling Jaya (S1), Shah Alam (S2) and Gombak (S3). The data from these three stations were compared with the data recorded at Jerantut, Pahang (B), a background station established by the Malaysian Department of Environment. Results show that the concentrations of CO, NO2 and SO2 are higher at Petaling Jaya (S1) which is due to influence of heavy traffic. The concentrations of PM10 and O3, however, are predominantly related to regional tropical factors, such as the influence of biomass burning and of ultra violet radiation from sunlight. They can, though, also be influenced by local sources. There are relatively stronger inter-pollutant correlations at the stations of Gombak and Shah Alam, and the results also suggest that heavy traffic flow induces high concentrations of PM10, CO, NO2 and SO2 at the three sampling stations. Additionally, meteorological factors, particularly the ambient temperature and wind speed, may influence the concentration of PM10 in the atmosphere

Ethnic Differences in Survival after Breast Cancer in South East Asia

Background: The burden of breast cancer in Asia is escalating. We evaluated the impact of ethnicity on survival after breast cancer in the multi-ethnic region of South East Asia. Methodology/Principal Findings Using the Singapore-Malaysia hospital-based breast cancer registry, we analyzed the association between ethnicity and mortality following breast cancer in 5,264 patients diagnosed between 1990 and 2007 (Chinese: 71.6%, Malay: 18.4%, Indian: 10.0%). We compared survival rates between ethnic groups and calculated adjusted hazard ratios (HR) to estimate the independent effect of ethnicity on survival. Malays (n = 968) presented at a significantly younger age, with larger tumors, and at later stages than the Chinese and Indians. Malays were also more likely to have axillary lymph node metastasis at similar tumor sizes and to have hormone receptor negative and poorly differentiated tumors. Five year overall survival was highest in the Chinese women (75.8%; 95%CI: 74.4%–77.3%) followed by Indians (68.0%; 95%CI: 63.8%–72.2%), and Malays (58.5%; 95%CI: 55.2%–61.7%). Compared to the Chinese, Malay ethnicity was associated with significantly higher risk of all-cause mortality (HR: 1.34; 95%CI: 1.19–1.51), independent of age, stage, tumor characteristics and treatment. Indian ethnicity was not significantly associated with risk of mortality after breast cancer compared to the Chinese (HR: 1.14; 95%CI: 0.98–1.34). Conclusion: In South East Asia, Malay ethnicity is independently associated with poorer survival after breast cancer. Research into underlying reasons, potentially including variations in tumor biology, psychosocial factors, treatment responsiveness and lifestyle after diagnosis, is warranted

Development of dense void-free electrospun SPEEK-Cloisite15A membrane for direct methanol fuel cell application: optimization using response surface methodology

Response surface methodology (RSM) was utilized to design the experiments at the settings of solution concentration, voltage and the collector distance. It also imparted the evaluation of the significance of each parameter on the resultant physico chemicals (proton conductivity, methanol permeability and water uptake). The investigations were carried out in the two-variable process domains of several collector distances as applied voltage and the solution concentration were varied at a fixed polymer molecular weight. The result showed that all three factors were found statistically significant in the production of void free electrospun SPEEK/Cloisite membrane. All responses were correlated to these variables by using a second order polynomial function. The optimum condition for void free electrospun SPEEK/cloisite was at 0.17 wt% concentration with applied voltage of 22.15 kV and 18.83 cm distance from needle tip to screen collector