Slope stability analysis with applicability of lime in capillary barrier effects

Many hill slope areas in Malaysia are vulnerable to soil erosion and shallow slope failures due to tropical climate and intense and frequent rainfall events. This failure can be attributed to the surface erosion, loss of shear strength, and formation of tension cracks on the surface. Lime as a construction material has been used to improve soil properties for long time. In this study a series of laboratory tests were performed on natural soil and soil artificially mixed with 3, 5, 7 and 9% of hydrated lime, based on dry unit weight of the soil. Numerical analysis was conducted using finite element method to simulate capillary barrier effects at the interface of soil and soil-mixture due to change in permeability. The results demonstrate that, for the soil used in this study, an addition of 7% lime is considerable to improve properties of the soil surface with optimum thickness of 30 cm in capillary barrier effects. The improvement of soil at slope surface not only prevents erosion and crack formation but also limits deep infiltration of rainwater into the slope which was achieved through numerical modeling. This study can be contributed to the path of stability of surficial slope failures

Study on water quality parameters of Linggi and Melaka rivers catchments in Malaysia

The Linggi and Melaka rivers catchments are among the most significant watersheds in the west coast of Peninsular Malaysia. However, Malaysia is a tropical country with approximately similar seasonal climate, in the monsoon period, water level of catchment is different. Recently in the supposed domain, due to raising the population and expanding urban areas, demand for water consumption is increased gradually. On the other hand, problem of water pollutions due to industrial activities have been signed out. Therefore, study on water quality and sources of pollutions in these regions became vital for public and private sections. This study was conducted to assess the water quality conditions in both rivers catchments. The observed water quality data for 5 years period (2004-2008) were obtained from Departments of Environments’ water quality monitoring stations in Malaysia. Statistical analyses have been carried out on three water quality constituents which are BOD5, NH3-N and TSS. The observed data were compared with the water quality criteria to identify the water quality violation level in both river catchments. Furthermore, the differences in water quality between base and storm flow events were examined using Box and Whisker Plots. Results of this study indicate that TSS and NH3-N are the primary causes for water quality impairment in Linggi River with concentration of about 78.3% and 81.8% respectively. However, for Melaka catchment, TSS is identified as the main cause of water quality impairment, when 64.4% of the total water samples exceed the standard. There are some point sources and non-point sources of water quality impacts in both watersheds. The results of this study would be contributed to development of best management practices for the Linggi and Melaka catchments and similar study areas

Improving soil properties to prevent surficial slope failure

Many hill slope areas in Malaysia are vulnerable to soil erosion and shallow slope failures due to intense and frequent rainfall events. Rainfall induced slope failure can be attributed to: seepage force and seepage erosion, the loss of shear strength of the soil, and formation of tension cracks. Lime was used to improve soil properties and resistance against failure. When mixed with in-situ soil, the lime can reduce the potential for swelling and shrinkage; therefore inhibit the formation of cracks at the surface. Lime can also reduce the soil’s dispersibility, therefore reduce the erosion potential. Soil mixed with lime has lower permeability, therefore enhance of capillary barrier effect and limit the rainfall infiltration into the soil. This study focuses on the improvement of soil properties to prevent surficial slope failure. Laboratory tests have been performed on soil and soil mix with deferent percentage of lime to evaluate properties of blended soil. The results show that the optimum lime content to be used in the mix design is 7%. A two dimensional finite element model of the slope was used to evaluate the performance of the optimum lime – soil mix as capillary barrier. The analysis revealed that the optimum thickness of slope cover system as capillary barrier is 30cm