Physical classifications and engineering characteristics of in situ boulders in tropically weathered granite

The issues of boulder in tropically weathered granitic rock masses have roused a lot of problems and risks to the work performances and design quality in civil engineering. Although the presence of in situ boulder could be predicted through several methods and classified in several weathering classification schemes, the behaviour of tropically weathered in situ boulder is not well understood. The aim of this study is to establish physical classification and engineering characteristics of granite boulders and to catalogue the boulders in tropical weathering profile. A total of 46 panels of granitic profile consist of 88 in situ boulders from five quarry sites located in Johor, Malaysia were investigated involving several field and laboratory test programs. The field test programs conducted include geological field mapping, discontinuity survey and classification of physical characteristics of boulder as well as its surrounding material in various weathering zones. The physical characteristics examined include occurrence of boulders in moderately to completely weathered zone, shape, size and rindlets characteristics from respective weathering zone. The laboratory test programs involve determination of physico-mechanical properties and mineralogical analysis. The field study revealed five dominant weathering profiles with different significant types of weathering zone and occurrence of in situ boulder. This finding indicated that in situ boulder is the main character in the formation of heterogeneous zone in weathering profile especially in the moderately weathered (Zone 3), highly weathered (Zone 4) and completely weathered zone (Zone 5). The angularity, size and rindlets characteristics of the boulder from moderately to completely weathering zones significantly differ from each other. Due to these significant differences, the in situ boulders formed in completely, highly and moderately weathered zones are classified into three major types, namely Type A, Type B and Type C, respectively. Boulder Type A is surrounded by double rindlets zones which classified as inner and outer rindlets, while boulder Type B possess single rindlets zone which is classified as inner rindlets. On the other hand, boulder Type C has no rindlets and it is surrounded by joints and fractures. The differences in physical characteristics of boulders Type A, B and C could be used to predict their existence in different weathering zones. The result obtained from the laboratory study revealed the physico-mechanical properties which include dry density, porosity, durability, strength and permeability of rindlets and saprolites found in completely weathered zone showed significant variance compared to highly and moderately weathered zone. In conclusion, the in situ boulders formed in moderately to completely weathered zones possessed significant variance of physical and mechanical characteristics which can be used as an indicator in weathering classification and engineering design purposes

Effect of Surcharges to The Stability of Mechanically Stabilized Earth Wall Using Finite Element Method: Back Analysis Study Case in Senai City Airport

Abstract: Mechanically Stabilized Earth (MSE) wall is a composite retaining structure construction made up of alternating layers of compacted backfill and soil reinforcing components. Surcharges on top of MSE wall is one of the factors that can lead to the failure of the MSE wall. In Senai City Airport, a MSE wall with high 9 m and length up to 400 m has been constructed. However, the effect of various surcharges of the MSE wall slope did not well investigate and was poorly understood. This study aims to investigate the effect of surcharge to the stress behaviour and the factor of safety of Mechanically Stabilized Earth Wall (MSE) wall using Finite Element Method (FEM). The study conducted using different loads in order to determine the stress behaviour and the safety factor of MSE wall using PLAXIS software. The geometry and parameters of sandy silt slope of Senai City Airport, Senai, Johor was taken from design consultant and previous soil investigation report, respectively. The soil parameters were used in this study are the unit weight of the soil, cohesion, Poisson Ratio, Young Modulus and the friction angle. This study gave the best result in order to determine the effect of surcharges to the behaviour of stress and safety factor of MSE wall. The highest total displacement was at 100 kN with total displacement 19.23m with 0.884 factor of safety. This study revealed the effect of various surcharges on the behaviour of stress and factor of safety of the MSE wall. The increase of surcharge increased the stress behind the wall and increased the factor of safety (FOS) when the loads was increased

Electrical resistivity and induced polarization techniques for groundwater exploration

Abstract: Electrical resistivity and induced polarization surveys have been conducted for groundwater exploration at two different sites of geological aged i.e. Carboniferous and Quaternary. This study discussed the earth materials resistivity and chargeability for metasedimentary rock and unconsolidated sediment for groundwater exploration at Kampung Jongok Batu, Dungun and Kampung Paya Rawa, Besut, respectively. For this study Terrameter LS2, cable, electrode, cable connector, battery and remote cable are tools for measurement. The spacing between electrodes is 5 m, maximum length of spread line is 400 m and using Pole-Dipole protocol. Via comparing between the resistivity and chargeability values able to provide better interpretation for ground water exploration for metasedimentary rock and unconsolidated quaternary sediment. The result shows the important of chargeability for refining the resistivity value for locating the groundwater position.Â

The Slope Failure of Weathered Granite Boulders by Using the Finite Element Method

An assessment of weathered granite profile of a research area at Mukim Senai, Kulai, Johor was conducted using PLAXIS 2D method. The slope stability of weathered granite is closely related to the geometric strength of the slope, slope height, soil type (sand or clay), slope gradient and depth to determine factor of safety. The aim of this research is to model and determine the factor of safety of the weathered granite slope with homogeneous characteristics using Plaxis 2D. In addition, it also aims to analyses and correlate the effect of shapes, size and distribution of boulders to the safety factor of the slope. Finite Element Method (FEM)) had been used through the application of PLAXIS 2D software. By comparing between the 2 methods that have been analyzed, safety factors for the slopes analyzed together with groundwater data is less safe. The Safety Factor has found less than 1.5 indicates a slope prone to landslides

Assessment of Tube Well Pumping Test Performance on Different Geological Formation

Water supply-demand is increasing in line with the increment in population. Natural water resources are declining due to a few factors of a reduction of water catchment areas, river pollution and drought. This causes the raw water quantity to decrease and its quality to be contaminated and resulting in higher water treatment costs. Groundwater usage is able to solve this problem due to its less pollution and requires minimal water treatment. The groundwater is preserved in aquifer within the geological formations, i.e., in the alluvium and fractured rock. However, the groundwater yield of each formation is unknown unless constructing the tube well and performed the pumping test. The study aim is to evaluate the tube well performance via pumping test on different geological formations. This research focuses on the effect of transmissivity, hydraulic conductivity, and efficiency of the aquifer, which are step-drawdown test, constant-rate test and recovery test in tube well in the geological formation of alluvium and fractured rock. Three well-pumping tests at each formation of alluvium and fractured rock were conducted at IBS Universiti Malaysia Kelantan (UMK), Kelantan, Sekolah Kebangsaan Chantum, Kelantan, Sekolah Menengah Kebangsaan Agama Tok Bachok, Kelantan, FRU Wakaf Tapai, Terengganu, Kampung Dada Kering, Kuala Lipis, Pahang, and Kampung Seri Gunung Pulai, Johor, respectively. The aquifer efficiency is obtained from the relationship between transmissivity and hydraulic conductivity. The suggested value of 75% efficiency is selected for presenting its well efficiency. The wells efficiency indicate that the alluvium formation was constantly higher between 9.39m3/h and 23.38m3/h. Meanwhile in the fractured rock formation were highly varied between 1.00m3/h and 32.33m3/h. The alluvium aquifer showed uniform water production compared to the fractured hard rock aquifer. Meanwhile, the water quantity in the fractured hard rock formation is unpredicted, which is subjected to the fractured rock characteristic

Physical characteristics of boulders formed in the tropically weathered granite

Deep weathering profile is a common phenomenon for humid tropic especially in Malaysia. The reactions of deep weathering under soil surface are decomposition of the massive rock and formation of thick stratum of soil and boulders. However, the occurrence of embedded boulders or loose blocks in the highly to completely weathered in the hilly area is not fully understood and investigated. This paper investigates the occurrence and physical characteristics of boulders in the granitic area. The parameters investigated are boulder’s discoloration, size, shape, rindlet properties and their distribution. Colour and shape were determined based on rock colour chart by Krumbein and Croft’s chart respectively. Size, rindlet and its distribution were determined based on field observation. Field results revealed that boulders in the hilly area can be found as shallow as 2 m from ground surface. In addition, it is found that boulder that embedded in deeper zone became larger in size and surrounded by thicker rindlet of up to 50 cm thick. Boulders embedded in soil stratum at weathering zone 4 and 5 are mostly independent and scattered around the weathering profile. The boulders can also be presented in various shapes; the smaller boulder is located at the upper zone more to flat to very spherical shape and rounded to well rounded edges, while the larger boulder that is located at lower zone more to sub-spherical shape and well rounded edges

Physical field characterization of boulders in tropical weathering profile - A case study in Ulu Tiram, Johor Malaysia

Boulder is known as one of the weathered products that formed by the disintegration and decomposition process of jointed rock mass, forming into spherical form by the reaction of concentric spheroidal weathering process. However, the physical characteristic of boulder in weathering profile where it is formed is not well understood. This paper is aimed to investigate the physical field characterization of boulders in term of its size, shape and distance from bedrock in the weathering profile. The study has been carried out towards six panels located at a granite quarry in Ulu Tiram, Johor. The initial finding indicated that the shape and the diameter of boulder were changing by the increment of the distance from bedrock but the pattern of the shape of the boulder showed that it did not depend on its diameter. It can be concluded that there are significant pattern and correlation between shape, size and the distance of boulder in the weathering profile

Peat Stabilization by Using Sugarcane Bagasse Ash (SCBA) as a Partial Cement Replacement Materials

Malaysia are covered approximately 2.6 million hectare of peat and facing serious geotechnical problems to develop infrastructure on peatland area. This study is to observe the basic geotechnical properties, strength and compressibility behavior of Pontian peat that stabilized by cement (OPC) and sugarcane bagasse ash (SCBA). The whole laboratory test standards and regulation that had been used in this study was adopted from American Society for Testing and Materials (ASTM) and British standards (BS). In order to understand an improvement of peat stabilization, unconfined compressive strength (UCS) and 1D-Oedometer consolidation test were conducted on untreated and stabilized peat. The results show that Pontian peat can be considered as hemic peat with average acidic. It was observed that the treated peat with 5% of SCBA (PCB5) has the highest UCS of 190 kPa and was discovered to be equivalent to PC specimen. There was a noteworthy decrease of void ratio, e for optimum PCB and PC mixtures as compared to untreated peat. The value of Cc and Cα was quite low at small effective stresses, however it improved after beyond preconsolidation pressure, σ’c. Compared to untreated Pontian peat which contributed the ratio of Cα/Cc about 0.056, stabilized peat for PC and PCB5 gave better ratio with 0.0316 and 0.0273 respectively. Results shows that the treated peat Cα/Cc ratios were drop dramatically from untreated peat which is representing the stabilized mixture can efficiently reduce the secondary compression

Keberkesanan kaedah pembelajaran berasaskan masalah dalam meningkatkan kemahiran berfikir aras tinggi dan menyelesaikan masalah dalam kalangan pelajar

Aspirasi negara yang diilhamkan dalam Wawasan 2020 ialah mencapai taraf negara maju. Hal ini telah meletakkan kepentingan yang sangat tinggi terhadap pendidikan sebagai pemacu untuk mencapai matlamat menjadi sebuah negara maju yang mampu mendepani cabaran dan permintaan ekonomi yang dipacu oleh sains dan teknologi, seperti yang telah digariskan dalam Pelan Pembangunan Pendidikan Malaysia. Pembelajaran Berasaskan Masalah (PBM) adalah satu pendekatan pengajaran berasaskan masalah sebenar, yang melibatkan penggunaan pelbagai kemahiran untuk menyelesaikannya. Kajian kuasi-eksperimental ini bertujuan mengkaji keberkesanan kaedah PBM dalam meningkatkan Kemahiran Berfikir Aras Tinggi (KBAT) dan kemahiran menyelesaikan masalah pelajar. Kajian ini mengambil masa selama lapan minggu. Instrumen yang digunakan dalam kajian ini ialah soalan ujian pra-pasca, senarai semak dan soal selidik. Kajian ini melibatkan 71 orang responden dari Sekolah Menengah Kebangsaan Tun Ismail yang terbahagi kepada dua kumpulan, iaitu kumpulan rawatan dan kumpulan kawalan. Kesemua responden ini ialah kumpulan pelajar yang mengambil mata pelajaran sains tingkatan empat. Data yang diperoleh dianalisis secara deskriptif dan inferensi menggunakan perisian Statistical packages for Social Science Version 21.0 (SPSS). Hasil dapatan kajian ini membuktikan kaedah PBM berjaya meningkatkan Kemahiran Berfikir Aras Tinggi (KBAT) dan kemahiran menyelesaikan masalah pelajar. Pelajar juga menunjukkan persepsi positif terhadap kaedah PBM ini. Dapatan kajian ini menggambarkan teknik pengajaran dan pembelajaran yang berbeza, menarik serta berkesan dari kaedah tradisional mampu meningkatkan kemahiran pelajar

Back Analysis and Potential Remedial Approach for Failure Slope at Bukit Nanas, Kuala Lumpur

This study aims to validate the design parameters and stability of the slopes failure and propose acceptable remedial work by assessing the slope stability in Bukit Nanas, center of Kuala Lumpur. The slopes’ height is around 40 and 60 m with the gradient around 30°-45°. Totally 7 boreholes be carried out and the pertinent engineering properties were analyzed from laboratory testing and back analysis (in situ test). An established computer program SLOPE/W was used to carry out for slope stability analysis. The analysis method adopted was Morgenstern-Price’s Method. Based on the result of the field investigation and numerical analysis, the model of lowest factor of safety (FOS) that evaluated from the existing slope in critical section were selected and recommended for remedial work. Two option of remedial slope design had been proposed. The first option is soil nailing with grid beam and proposed drain while the second option is hybrid anchor with grid beam and proposed drain. Both options are used to improve the slope stability, but first option had been chosen as higher FOS and more efficient option. This remedial approach based on the main cause of slope failure in Malaysia can applied as reference in future slope remedial design