Slope stability of landfill with waste degradation

Nowadays, a large amount of municipal solid waste (MSW) is generated due to the rapid urbanisation in developing countries leads to the demand for larger and higher capacity landfills. Bioreactor landfill technology has been introduced to accelerate the stability of landfill and to solve the issue of limited landfill area. However, the accelerated degradation of the refuse in bioreactor landfills also considerably changes the geotechnical characteristics of the waste in the landfill and thereby increases the concern for waste stability. Hence, this study aims to analyse the stability of both conventional and bioreactor landfill slope with the effects of waste degradation. Finite element method has been used in the slope stability analysis and the stability is presented by the factor of safety. The objectives of this study are i) to determine and assess the main parameter which influences the stability of the waste slope, ii) to determine the effects of waste degradation to the waste properties and iii) to obtain the factor of safety of the landfill slope using numerical analysis by finite element method. From the literature review, it is found that slope stability of a landfill mainly depends on the geotechnical properties of waste, such as moisture content, unit weight, shear strength parameters and hydraulic conductivity of waste. After the degradation process, engineering properties of field refuse are affected which includes the increased pore-water pressure and unit weight, decreased strength and lower hydraulic conductivity. Based on the analysis of conventional landfill slope stability by using Plaxis software, slope ratio of 1:3, 1:4 and 1:5 calculated safe with 1.69, 2.3 and 2.8 whereas the analysis of bioreactor landfill slope stability calculated safe only for slope ratio of 1:4 and 1:5 with 1.60 and 1.97. Moreover, the factor of safety for steeper slopes is lower and vice versa. From the parametric analysis, it is found that the full height of slope and unit weight of waste input affect the result analysis. This study is significant to evaluate the landfill slope stability with the effects of waste degradation and to ensure both conventional and bioreactor landfill slope stability for long periods. © BEIESP

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

The potential of shear wave velocity as an erosion risk index

Soil erosion is a captious environmental problem in regions of hot tropical climates, causing loss of land and natural disasters such as river sedimentation, flooding, and slope failures. Based on soil properties and their response to erosion agents, efforts have been made to develop simplified models and indices for the estimation of erosion. ROM scale is proven to be effective in forecasting risk levels for erosion assessment. However, the method requires soil sampling and laboratory experimentation, which is time-consuming and laborious, especially when analyzing huge areas. Therefore, this study aims to develop a relation between ROM scale and shear wave velocity estimated by the spectral-analysis-of-surface-waves (SASW) method. For this purpose, 36 soil samples were extracted, and twelve SASW tests were conducted at twelve sites identified along Sungai Langat. Soil particle distribution was carried out to calculate the ROM erosion index value for all the extracted soil samples. The fast Fourier Transform (FFT) algorithm was used to transform the time-recorded signals into the frequency domain, and the dispersion curves were generated after the masking process. The shear wave velocity erosion risk ranged from 10 m/s to 120 m/s, indicating critical risk and low risk, respectively. Low erosion risk levels were observed for high shear wave velocity values, representing a decaying pattern in exponential relation. The resulting correlation between ROM scale and shear wave velocity produced a coefficient of determination value of 0.71, indicating a strong relation. This study indicated the potential of shear wave velocity as an erosion risk index

Prediction of bearing capacity of shallow sites by seismic method

This paper presents a study of estimating bearing capacity of shallow sites using an alternatives method, which is nondestructive in nature without performing any borehole. Initially, two important parameters, which are, shear wave velocity profile and damping collected by means of Spectral Analysis of Surface Waves method. Shear waves velocity used to provide an elastic Shear Modulus G, and Young’s Modulus, E. Damping at current strain is obtained by using Halfpower Bandwidth Method with various sources from possible low to high frequency. Both parameters, which is measured at low strain, used to adjust to larger strains through hyperbolic relationships with reference strains obtained from the equation. Comparison to conventional method Plate Load Tests and an empirical equation provided previous researcher were made and good agreement achieved by different of 10%

Persepsi pelajar mengenai aplikasi quizizz dan padlet bagi kursus kejuruteraan geoteknik

Kejuruteraan Geoteknik adalah salah satu sub bidang didalam kejuruteraan awam. Kursus ini melibatkan penggunaan prinsip asas geologi dan mekanik tanah dalam penentuan rekabentuk dan pembinaan struktur tanah yang selamat. Dalam konteks pengajaran di kuliah, kaedah tradisional seperti slaid and buku teks dilihat membosankan kerana pengajaran hanya berbentuk satu hala dan pelajar tidak mempunyai medium untuk berinteraksi. Oleh itu, pendekatan di dalam kuliah yang berkesan dapat memastikan pemahaman yang lebih baik serta penguasaan terhadap konsep asas dalam kejuruteraan geoteknik. Objektif kajian ini adalah untuk mendapatkan persepsi para pelajar mengenai pendekatan pengajaran yang sesuai dijalankan di kuliah menggunakan aplikasi Quizizz dan Padlet bagi kursus Kejuruteraan Geoteknik. Seterusnya, ia juga bertujuan untuk mengenal pasti kaedah terbaik yang wajar digunapakai bagi kursus Kejuruteraan Geoteknik. Sekain itu, kajian ini turut menilai kesan pendekatan mengunakan kedua-dua aplikasi tersebut terhadap tahap pemahaman pelajar serta keterlibatan pelajar secara aktif semasa sesi kuliah berlangsung. Kajian ini melibatkan soal selidik ke atas pelajar prasiswazah Tahun 3 sesi akademik 2022/2023, Ijazah Sarjana Muda Kejuruteraan Awam, Universiti Kebangsaan Malaysia yang mengikuti kursus ini. Soal selidik bagi kajian ini dilakukan secara atas talian, dimana pelajar perlu mengisi tinjauan tersebut pada hari terakhir sesi kuliah dijalankan. Daripada kajian yang dijalankan, didapati sebanyak 82.10% pelajar bersetuju dengan perlaksanaan aplikasi Quizizz dan 57.10% pelajar bersetuju dengan perlaksanaan Padlet semasa kuliah diajalankan. Namun, terdapat 35.70% pelajar menjawab tidak pasti, 5.40% tidak setuju, dan 1.80% sangat tidak setuju dengan penggunakan aplikasi Padlet kerana mereka seringkali mempunyai kesukaran ketika ingin memuat naik fail. Aplikasi Quizizz turut dilihat mempunyai potensi untuk dijadikan sebagai e-penilaian. Hal ini kerana aplikasi tersebut dapat mengira markah pelajar secara automatik dan sekali gus dapat meringankan beban tugasan pelajar serta beban ahli akademik untuk menanda markah tugasan

THE EFFECTIVENESS OF INDUSTRIAL TRAINING FROM THE PERSPECTIVE OF STUDENTS OF THE CIVIL AND STRUCTURE ENGINEERING DEPARTMENT

This paper discusses the effectiveness of the industrial training from the perspective of students who have undergone 12 weeks of industrial training. A questionnaire was distributed to 47 Third Year students at the Civil and Structural Engineering Department (JKAS), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM). The sample comprise of 21 male and 26 female students. The questionnaire consists of three parameters, namely students’ knowledge, skills, and attitude towards industrial training. These parameters were identified as three domains of educational activities based on Bloom’s Taxanomy. Students were required to answer 23 questions to assess their perception before and after undergoing industrial training. The Likert scale used in the questionnaire comprises of a one to five level of satisfaction scale (1 = not at all satisfied to 5 = extremely satisfied).The Winstep and Microsoft Excel software was used to analyse the survey. Winstep was used to evaluate the validity and reliability of the questions, while Microsoft Excel was used to assess the effectiveness of the industrial training from students’ perspective, namely whether their perception has improved, remain unchanged, or decreased. The Rasch Model analysis showed that the questionnaire is reliable and valid. Fifty percent of the students said that industrial training had increased their knowledge and skills, while 39 percent of the students admitted that their attitude remain unchanged after completing their industrial training. Findings on knowledge and experience acquired by the students during industrial training could serve as guidance when planning for a better career in the future as well as to the industrial training programme

Soil Parameters Model Prediction via Resistivity Value Limit to Shallow Subsurface Areas

Geotechnical engineering design necessitates a study of soil parameters for calculation purposes. As a complement to the conventional method, a resistivity survey can give preliminary results in a short amount of time. This study uses a statistical analysis program to show a correlation and regression for predicting soil parameters based on the resistivity value. Sixty-six data points for each soil parameter and resistivity were used for statistical analysis from six profiles of the study area as a part of the investigation. The soils are sampled by drilling the borehole up to a depth of 3 meters. The Wenner array was applied to conduct a resistivity survey. The collected data were utilized to establish a correlation between resistivity (ρ) and soil parameters such as moisture content (w), clay content (clay), plasticity index (PI), friction angle (ϕ), bulk density (γ), and porosity (n). The generated statistic model was improved through several iterations for each correlation. For the ρ-w, ρ-clay, ρ-PI, ρ-ϕ, ρ-γ, and ρ-n relationship, the total iterations are 5, 4, 7, 6, 5, and 4 for each correlation, respectively. Resistivity and moisture content showed a significant power correlation, followed by a modest relationship between resistivity and porosity. Between resistivity and other parameters, relationships such as clay content, bulk density, friction angle, and plasticity index were found to have very weak or no association. However, some trends can be seen clearly. This study aims to offer the geotechnical engineer a quick preliminary way of obtaining the associated soil parameters for various geotechnical calculations employing the resistivity approach based on the developed numerical equation

The evolution of spectral analysis of surface wave method – a review

Spectral analysis of surface wave (SASW) method for in-situ non-destructive testing of stiffness profiles of soil and pavement sites have undergone various improvements since its inception during the 1980s. Improvements have been in both data-acquisition (sampling and sensors) as well as in data-processing (forward calculation and inversion algorithm) aspects. The present study explores the relative effectiveness of using SASW and its automation. Precise recording of amplitude value has the potential to further improve the effectiveness and develop the surface wave testing methods. Different approaches for interpreting the dispersion curve and their potential regarding sensitivity to noise, reliability, and capability to extract significant information were investigated. Finally, the suitable algorithms, finite element modelling, data acquisition and processing and the inversion procedure to provide the reliable and robust stiffness profile were illustrated in this study. After reviewing a few inversion analysis techniques, a non-linear minimization technique could perform reasonably well, which is fully automated despite some limitations. The artificial neural network could be implemented to generate the shear wave velocity profile from the dispersion curve and perform well for the upper layer’s parameters

Study of residual soil slope stability with the application of horizontal drainage

This study determines the effectiveness of horizontal drains on a slope which refers to a landslide at Putrajaya, Malaysia, in 2007. The incident buried 27 cars, and about 1200 people were transferred to a safe place. The main cause was identified as continuous and heavy rainfall. In Malaysia, abundant rainfall is common during the wet season. Therefore, one of the remedial measures to improve slope stability is applying horizontal drain to flush out rising groundwater and increase soil strength. In this study, the finite element method package, Plaxis, is used to analyze the slope stability changes in terms of the factor of safety (FOS). The simulation of slope behavior includes the horizontal drain conditions in lowering the groundwater level based on three parameters: the heights, appropriate depth, and inclination angle. The horizontal drains are installed at four different heights of 1 m, 2 m, 8 m, and 28 m from the toe of the slope. Based on the results, the horizontal drain is most efficient to be installed with 15 m long and zero degrees angle at the height of 1 m from the toe of the slope. At 2 m height, the drain should be installed with 26 m long and an angle of 1.8 degrees, and at 8 m height, the drain should be installed with 12 m long and an angle of 4.8 degrees. Moreover, at 28 m, the horizontal drain should be installed 20 m long and at an angle of 8.5 degrees. Therefore, this paper highlights the exceedingly appropriate design of horizontal drains at different heights, lengths, and tilt angles along the slope surface