3D numerical modelling of shallow tunnel in weathered granite incorporating multi-stage excavation and pre-support

Generally tunnelling in urban ground condition is not always favourable due to the tunnels’ susceptibility to major displacement especially when excavated in the soft soil and/or weak weathered rock formation. Apart from conventional support systems, pre-support measure like forepoling umbrella arch is frequently used to reinforce the ground. Modern computational tools allows the inclusion of multi-stage excavations and pre-support which was not possible in two dimensional (2D) plane strain. This paper demonstrates the three dimensional (3D) finite element analysis of Pahang-Selangor raw water transfer tunnel, as a reference case, where multi-stage excavation and pre-support are incorporated as intrinsic part of the model. The New Austrian Tunnelling Method (NATM)-3 segments which encountered Grade III weathered granite, having shallow overburden cover, was selected for numerical analysis using RS3 software. Comparison between simulated and observed data has shown good agreement during verification

The effect of vehicle weight on the sound produced by transverse rumble strips

Transverse rumble strips (TRS) are commonly used as traffic calming measure in the vicinity of premises. So far research have been extensively concentrated on the effect of vehicle type and speed on the noise produced by TRS, and very little research focused on the effect of vehicle weight. Do these vehicles produce extremely higher sound level parallel to their heavier weight? This is important as in reality, traffic flow consist of light, medium and heavy vehicles, which are also important sources of noise. This study investigated the effect of vehicle weight, such as gross vehicle weight (GVW) when transited on TRS, particularly with emphasis on impulsivity content. The objectives of this research were to: (1) determine the effect of GVW on noise generation when a vehicle transits on TRS and (2) assess the effect of GVW on the impulsivity of noise. Data from vehicles with weight between 800 kg - 8000 kg were collected based on previous research where these vehicles were tested on speed values of 30km/h and 50km/h. It was found that when the vehicles transited on TRS, the generated noise was strongly related with the vehicle weights (R2=0.71) higher than those normal road surface (R2=0.49). However, the changes of noise were not well represented by direct relation. It was found that TRS can increase and decrease the sound pressure level, depending on GVW, but on average, TRS can increase the sound pressure level by 1 dBA. Despite that, TRS was found to have an impulsive characteristic within the tested speed range. This finding can facilitate the authority to evaluate the environmental noise produced by TRS

Strength behaviour of kaolin treated by demolished concrete materials

Kaolin has claynite structure in nature, presenting several properties which may justify in many engineering and industrial applications. However, this type of soil is categorised as problematic soil because the presence of claynite properties eventually resulting the kaolin to have low shear strength and high compressibility as other clay soil. Due to that weakness, kaolinite does not meet the requirements necessary for any construction purposes particularly at the preliminary stage. Hence, to overcome this issue, soil stabilisation process is needed prior any construction works. The aim of this study is to determine the strength characteristics of stabilised soft clay soil (Kaolin S300) with demolished concrete materials (DCM). The selection of DCM as the stabilizer for the purpose reutilisation of waste materials that currently has been a great concern for the environmental sustainability. The percentages of DCM content used were 5%,10%,15%20%,25%,30% with varying curing time of 7days, 14 days and 28 days, respectively. Based on the result it was reported that, the unconfined compressive strength (UCS) test shows that the highest strength value obtained of 595.6 kPa kaolin treated with 30% DCM at 28 curing days. It is equivalent to 92% increment from the untreated kaolin sample at 0 days. However, the optimum amount of DCM which provides significant strength improvement was found when more than 20% of DCM is presented after 14 curing days. Hence, it shows the possible usage of DCM as waste material to effectively stabilize kaolin at specific amounts sufficiently

Interrelationship between borehole lithology and electrical resistivity for geotechnical site investigation

In the modern era of geophysics, Electrical Resistivity Tomography (ERT) is an important tool to be use for early prediction of subsurface mapping. ERT act to inject electric current to the ground to study the chargeability or the resistivity value of a material. Engineers, geologist and researchers can apply ERT for their subsurface investigation since ERT proves to be very efficient and effective for subsurface mapping in term of cost, time and data coverage. 2D Electrical Resistivity Tomography survey was performed in Kuala Krau, Temerloh, Pahang to assist geotechnical site investigation. There are two available boreholes (BH 1 and BH 2) lithological data which can be correlated directly with the resistivity profile. One of the boreholes report hard rock layer at 9 m depth overlain by silt and clay. This hard layer was represented by resistivity value higher than 600 Ω m and 10–70 Ωm low resistivity layer overlain the hard layer. The low resistivity layer is associated with saturated silt and clay. Another borehole shows the existence of weathered sandstone at depth 11 m–17 m also overlain by silt and clay. Resistivity profile show the weathered region from the said borehole contacted edge side of sandstone boulder which also represented by higher than 600 Ω m resistivity value. 3D voxel was also generated from inversed resistivity value. The 3D voxel has successfully shown the lateral distribution of the geotechnical target. In conclusion, from this study, it is proven that results from ERT can be verified with the results from borehole lithology since the results obtained were almost accurate

Load-deformation analysis on a slope at Gunung Pulai water treatment plant, Sultan Ibrahim reservoir

The Sultan Ibrahim Reservoir located at Gunung Pulai catchment area was previously managed by the Singapore's Public Utilities Board before the Board handed over the reservoir to Johor State Government under current management of the Syarikat Air Johor. At the present time, the Syarikat Air Johor is operating a Gunung Pulai Water Treatment Plant consisted of two main plants, i.e. Water Sedimentation Plant and Water Filtration Plant for treating raw water from the reservoir before supplying to the consumers. However, the integrity of water treatment plant's structure should be checked due to several cracks were observed, and moreover the structure was built over more than 90 years. The formation of the cracks in the Gunung Pulai Water Treatment Plant may be induced by movement of the sloping area to the south-east of Water Sedimentation Plant. The calculated Factor of Safety (FOS) via sensitivity analysis for cross sections of original slope indicates any decrease in friction angle and/or cohesion strength or increase in horizontal seismic load will further cause instability on slope. Also, the results of Load-Deformation analysis on cross sections of original slope show significant vertical displacement and horizontal displacement on the bottom and both sides of sedimentation tanks, respectively. The results indicate applied structural and water loads significantly affect deformation at both vertical and horizontal directions which could have contributed to FOS < 1 in slope stability analysis

Effect of ground granulated furnaces blast slag on kaolin properties

Kaolin is widely known to possess high compressibility and low strength that leads to infrastructure collapse. Nevertheless, it is crucial to produce soil with such properties because of its immense demand by the infrastructure section amidst the rapidly growing population in Malaysia. The soil must be stabilised before construction so that several critical characteristics can be enhanced. Soil stabilisation finds extensive use in the treatment of the subgrade layers concerning road building. The objective of the study is to ascertain how the physical characteristics of kaolin change upon treatment with different concentrations of granulated ground furnaces blast slag (GGBS); changes in particle size and compaction properties are some areas of interest. Furthermore, the study assesses how a specific quantity of GGBS may be used for enhancing kaolin strength when it is cured for up to 28 days. Seven days curing time for 20% and 25% GGBS-kaolin blend leads to strength enhancement that exceeds the subgrade layer requirement. Considering the case of 25% GGBS-kaolin blend cured for 28 days, the maximum strength was determined to be 8.4 MPa. The inclusion of GGBS leads to changes in crystal phase and structure which can be observed using microstructure analysis

Estimation of soil water characteristic curves (SWCC) of mining sand using soil suction modelling

Soil water characteristic curve (SWCC) is widely known as the relationship between matric suction and water content. It is used as a tool to determine the hydraulic and mechanical behaviour of unsaturated soils and to predict soil water storage. Direct measurement is difficult and time-consuming. Many empirical models have been developed to represent SWCC. The objective of this study is to validate the Van Genuchten and Fredlund and Xing models. The SWCC was obtained from pressure plate tests for different soil gradations of mining tailing sand samples taken from Kuala Trong, Taiping, Perak, Malaysia. The results presented include moisture content and degree of saturation versus matric suction. The constructed SWCCs were fitted using the Van Genuchten and Fredlund and Xing equations, and the behaviour of the parameters analysed and discussed. The study found that this method is good for the SWCC for mining tailing sand, and that SWCC is greatly affected by initial water content and the grain size of the sample

Review on traffic noise problem in Malaysia

Malaysia is now experiencing rapid improvements in fulfilling its goal of achieving the status of a developed nation by year 2020. The nation's economy has grown rapidly with the opening of many new industrial and residential areas as well as infrastructure which in turn influence the ease in transportation and mobility. The Ministry of Transportation Malaysia has reported increases in the number of registered vehicles by a rate of 45 percent per annum from 2012 to 2014. All these have undoubtedly add to the road traffic noise that is linked to various health diseases, even though the Malaysian government has made tremendous efforts to improve the noise environment by introducing new guidelines. This paper presents the extent of the traffic noise problem in Malaysia together with the development of a traffic noise model and the current steps taken for traffic noise mitigation. The paper also discusses the challenges in overcoming this problem and concludes with a proposed traffic noise control plan for further consideration by town planners and land developers

Application of Digital Image Processing Technique in Monitoring LNAPL Migration in Double Porosity Soil Column

This paper investigates the phenomenon of light non-aqueous phase liquid (LNAPL) migration in double porosity soil. Investigation on the migration of LNAPL in double porosity soil was performed on aggregated kaolin using the digital image analysis. The photographic technique was used to capture the migration of LNAPL in aggregated soil samples. The captured digital images were fed through an image processing code to convert them to the hue-saturation-intensity (HSI) format which were subsequently used to plot the 2D LNAPL migration behaviour. The results of Experiment 1 and 2 show that the LNAPL moved downward faster when the moisture content increased. Another observation was that the kaolin granules started to disintegrate at a water content of 35%. In conclusion, using image analysis technique has enabled the researchers to monitor and visualize the LNAPL migration in the double porosity soil columns based on HSI values. The contour plots of HSI intensity value has provide detailed and useful information for future research

Application of unmanned aerial vehicle (UAV) for slope mapping at Pahang Matriculation College, Malaysia

This paper discusses the applications of unmanned aerial vehicle (UAV) for slope mapping which located at Pahang Matriculation College, Malaysia. Mapping is very important to obtain the terrain profiles for study area. By using UAV and commercial software, important information of slopes including perimeter, area and volume will be determined. With the development of modern technology, the utilization of UAV to gather data for mapping becoming easier as it is quick, reliable, precise, cost-effective and also easily to operate. High imagery quality is essential for the effectiveness and nature of normal mapping output such as Digital Surface Model (DSM) and Digital Orthophoto. With the help of established software, the dimensions of selected study area can be determined easily which can be considered as the main interest in this study. In addition to that, the cross-section of selected area can be obtained which help to determine the highest and lowest point of each area together with the terrain profiles. These slope profiles are determined according to their respective axis (vertical and horizontal) since both axis give different terrain profiles for each slope. Other than that, this research was further extended by determining the potential slope hazard based on their respective angles. These determinations are very important as early precautionary steps for engineers and researchers to prevent from any danger, injuries and accidents that for worse may cause fatalities