Habib Musa Mohamad
Faculty of Engineering, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah,

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Maximum Strain Effect and Secant Modulus Variation of Hemic Peat Soil at large Deformation due to Cyclic Loading Habib Musa Mohamad; Adnan Zainorabidin; Mohamad Ibrahim Mohamad
Civil Engineering Journal Vol 8, No 10 (2022): October
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2022-08-10-015

Abstract

This study presents the findings obtained in post-cyclic behaviour and degradation of shear strength from the static triaxial test, cyclic triaxial test and post-cyclic monotonic triaxial test to study the dynamic loading relationships with the degradation of shear strength after cyclic loading to the maximum strain effect due for Hemic peat soil and aim of this research was to assess the post-cyclic loading condition that brought to the understanding of secant modulus by using dynamic triaxial apparatus. It begins with a visual inspection of fibre characteristics. This is followed by an analysis of static, cyclic, and post-cyclic loading with stress-strain behaviour. Shear strength decreased and notched lower strength than its initial strength. As a matter of fact, PNpt-25 kPa from 1, 2, and 3 Hz are accumulated in the adjacent maximum strain. With regards to this maximum strain, the undrained shear strength ratio shows sequent decreases from higher to lower frequency applied. For instance, PNpt-25 kPa-1Hz to PNpt-25 kPa-3Hz recorded 1.16 to 1.13 undrained shear strength ratios, respectively. The secant modulus (Esec) for all specimens reflects decrement. The secant modulus for BSpt at an effective stress of 100 kPa in static monotonic is about 18.74 MPa, while in post-cyclic, the secant modulus expanded to 19.630 MPa cyclically loaded with 1 Hz. Unfortunately, the secant modulus returned to decline position when higher frequency applied at 2 Hz, where the secant modulus is about 12.781 MPa and continues to decline with 3 Hz at 7.492 MPa. Doi: 10.28991/CEJ-2022-08-10-015 Full Text: PDF
Post-cyclic Loading Relationship Effects to the Shear Stress and Cyclic Shear Strain of Peat Soil Habib Musa Mohamad; Adnan Zainorabidin
Civil Engineering Journal Vol 8, No 12 (2022): December
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2022-08-12-08

Abstract

Peats originate from plants and denote the various stages in the humification process. This condition renders the peat extremely soft and can be considered problematic soil. Thus, this study is conducted to examine and comprehend the particularities of peat engineering behaviour in respect to the relationship effects to the shear stress and cyclic shear strain of peat soil various characteristics to establish suitable correlation. This study carried out by using triaxial testing described by geotechnical test standards BS-1377: Part 8: 1990. Methods of Testing Soils for Civil Engineering Purposes: Shear Strength Tests (Effective Stress) that required for consolidated undrained and consist of five main stages: saturation, consolidation, static, dynamic, and post-cyclic loading using the GDS Enterprise Level Dynamic Triaxial Testing System (ELDYN). The parameters of shear strength were obtained in the peak deviator stress at a maximum of 20% of axial strain by using an undisturbed sample with an effective pressure imposed of 25, 50, and 100 kPa. In this study, all specimens are subjected to cyclic loading up to 100 cycles based on a one-way loading system with strain-controlled conditions. Based on the analysis conveyed, the post-cyclic shear stress decreased compared to its initial value of about 65.56 kPa (PNpt-100 kPa) in static and decreased to 14.9616 kPa in post-cyclic (PNpt-25 kPa-1 Hz). The principal stress ratio (σ'1/σ'3) shows the maximum values of this ratio that are located in the narrow zone of 1.61 to 1.12. Doi: 10.28991/CEJ-2022-08-12-08 Full Text: PDF
Peat Soil Compaction Characteristic and Physicochemical Changes Treated with Eco-Processed Pozzolan (EPP) Mohd Syeddre Sutarno; Habib Musa Mohamad
Civil Engineering Journal Vol 9, No 1 (2023): January
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2023-09-01-07

Abstract

Peat soil was defined as the highly organic surface layer derived primarily from plant remains. Peat, on the other hand, was the subsurface of wetland systems, consisting of unconsolidated superficial layers with a high non-crystalline colloid (humus) content. Peat soils have a low shear strength of 5 to 20 kPa, a high compressibility of 0.9 to 1.5, and a high moisture content of >100%. The purpose of the study was to prognosticate the potential of Eco-Processed Pozzolan (EPP) as peat soil stabilization material with improved technique and its consequence of the methods, which was the peat soils index properties and analyse the characteristics of the peat soil stabilization before and after treatment using Eco-Processed Pozzolan (EPP). The soil was mixed with 10, 20, and 30% Eco-Processed Pozzolan (EPP) and then compacted (compaction test) in a metal mould with an internal diameter of 105 mm using a 2.5 kg rammer of 50 mm diameter, freefalling from 300 mm above the top of the soil Three layers compaction of approximately equal depth and 27 blows spread evenly over the soil surface for each layer. The expected result to accomplish the main purpose was to prognosticate the potential Eco-Processed Pozzolan (EPP) as peat soil stabilization material with improved technique and its consequence of the methods. According to the findings, peat soil treated with EPP will transform its qualities from peat to usable soil. However, the presence of moisture will reduce the mixture's ability. According to the findings of this study, the optimum EPP for stabilizing peat soils was 30-40%. Correspondingly, the elemental composition of peat soil mixed with EPP improved regardless of Carbon, Ca composition. Comparatively, the amount of Silicon, Si increased from 6.5% (Peat + EPP 10%) to 12.9% (Peat + EPP 40%) due to the crystallization of EPP and peat. Doi: 10.28991/CEJ-2023-09-01-07 Full Text: PDF
Stress Path Behaviour and Friction Angle Transition Due to the Cyclic Loading Effects Habib Musa Mohamad; Adnan Zainorabidin; Adriana Erica Amaludin
Civil Engineering Journal Vol 9, No 4 (2023): April
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2023-09-04-010

Abstract

In various aspects, peat soil is different from mineral soil. Peat is a biogenic deposit that emerged within the last 10,000 years, during the post-glacial (Holocene) era. Peat is a soft soil that is unable to support external loads without experiencing significant deformations. Tyre pressure from automobiles and/or aeroplane wheels on paved surfaces creates traffic load, which can manifest as static or dynamic types of loading. To resolve the problem with peat soils, a thorough understanding of the static and dynamic behaviour of peat is still required. Many people who live near regularly used highways feel traffic vibration, and it is important to comprehend the nature of this issue to make predictions about potential solutions to this problem. As such, this study aims to investigate the cohesion (c) and friction angle (φ) properties of peat soil after it has been subjected to cyclic stress. Monotonic triaxial tests are conducted to ascertain the initial shear strength characteristics of the soil. Cyclic triaxial tests are performed with half of their maximum deviator stress to simulate the behaviour of peat soil under various effective stresses and frequencies of loading that are applied with 100 number of cycles. After applying various numbers of cycles of dynamic loading, the post-cyclic monotonic shear strengths were subsequently evaluated. It has been noted that irregular behaviour tends to occur more frequently at higher frequencies, particularly between 2 and 3 Hz. With higher frequencies being applied, the reduction in cohesion and friction angle becomes more evident. Doi: 10.28991/CEJ-2023-09-04-010 Full Text: PDF
Relationship of Rainfall Intensity with Slope Stability Mohammad Haziq Rosly; Habib Musa Mohamad; Nurmin Bolong; Noor Sheena Herayani Harith
Civil Engineering Journal Vol 9 (2023): Special Issue "Innovative Strategies in Civil Engineering Grand Challenges"
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-SP2023-09-06

Abstract

The impact of rainfall on landslides is not an uncommon issue worldwide, including in Malaysia. It is a major challenge for geotechnical engineers to ensure the constructed slope is safe and can sustain longer periods of time, including during heavy rainfall. Kota Belud, Sabah, has been selected as the study area to meet the study objectives. Heavy rainfall has been recorded every year within Kota Belud, which has caused a repetition of landslide occurrences within the hilly areas, especially during the monsoon season. Presently, there is no local procedure for determining the rainfall intensity value for slope stability analysis. This study utilized the rainfall intensity value from Hydrology Procedure 26. Seepage analysis conducted shows rainwater infiltration has caused the groundwater level to increase from rainfall starts until 0.5 m below ground level and decrease after rainfall stops, creating fluctuations in the groundwater level during the wet and dry conditions within the wetting front. The factor of safety of the slope shows a decreasing trend, with a reduction of around 27 to 33% after 24 hours of rainfall in conjunction with the changes in groundwater level. However, the factor of safety increased by around 3% from the initial condition after 48 hours. The objective of this study is to identify the factor of safety of a rainfall-induced slope within Kota Belud utilizing the rainfall intensity design limits from Hydrology Procedure 26. Doi: 10.28991/CEJ-SP2023-09-06 Full Text: PDF
Characteristic and Physicochemical Properties of Peat Soil Stabilized with Sodium Hydroxide (NaOH) Habib Musa Mohamad; Mohd Fahmie Izzudin Sharudin; Adriana Erica Amaludin; Siti Nor Farhana Zakaria
Civil Engineering Journal Vol 9, No 9 (2023): September
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2023-09-09-09

Abstract

Peat in various phases of decomposition has poor shear strength and high compressive deformation. For this research study, it will focus on stabilizing peat soil using NaOH. There are two main tests that were conducted in this research study, which are index property testing and the compaction test. For index property testing, there were six (6) experiments conducted to study the index properties of disturbed peat soil, which are moisture content, fiber content, organic content, liquid limit, pH, and specific gravity. Then, for the compaction test, a 4.5kg rammer was used to determine the best mixture of stabilizer blended with different volumes of 5%, 7%, and 9% stabilizer. The desired outcome of this study is to stimulate further research into the use of the chemical NaOH as a peat soil stabilizer for improved soil usage. 7% and 9% of NaOH only have a slightly different percentage, and it can be concluded that this was the optimum percentage of NaOH as a chemical stabilizer for peat soil. It can be seen clearly that 5% is the higher dry density with a lesser moisture content of the peat. When the percentage of NaOH was increased, the graph pattern also changed. NaOH has been observed as an alteration agent for peat soil dry density. It can be seen clearly that 5% NaOH is the higher dry density of the peat with the lesser moisture content and is suitable as a peat soil stabilizer. The increment of oxygen content recorded changes from 13.3% to 23%, while the sodium (Na) content decreased significantly with the increment of oxygen (O). Sodium content decreased from 8.7% for untreated specimens to 4.5% and 5.5% when peat was treated with NaOH, with 5% of NaOH and 9% of NaOH. Doi: 10.28991/CEJ-2023-09-09-09 Full Text: PDF