Ramli Nazir

Behaviour of expanded piles under upward loading due to radial preloading in soft clay

A two-dimensional numerical analysis was employed to evaluate the radial preloading effects on the bored piles bearing capacity under upward loading. Verification of the numerical model was conducted by comparing the calculated allowable load capacity based on a series of physical models in the small scale. Interpretations of the finite elements models were focused on the load-displacement behaviour, the effect of the increase in the pile diameter on the pile load capacity, deformation of the surrounding soil due to radial preloading and comparison of different constitutive models. The results revealed that the bearing capacity is increased due to impose of radial preloading for bored piles, meaningfully. In addition, the effect of the radial preloading is increased on the bearing capacity with increase in the pile diameter. In another aspect, the simulation of the pile behaviours based on the different constitutive models demonstrated that soft soil model can properly simulate pile behaviour due to radial preloading in comparison with Mohr-Coulomb model.

Peaty Soil Improvement by Using Cationic Reagent Grout and Electrokintic Method

Peat is known as soft soil with low shear strength and high compressibility. Electrokinetic injection technique is being used by applying a direct electrical potential across the soil specimens to improve physicochemical characteristics of the peat. Such applications cause electrochemical effects on the soil, leading to changes in the soil’s chemical, physical, and mechanical properties. This paper presents the results of the undrained shear strength, pH, water content across the electrokinetic box after injecting the cationic grouts. Four cationic grouts namely; calcium chloride, calcium oxide, Aluminum hydroxide, and sodium silicates were selected as grout. The microstructures of the stabilized peats were investigated by scanning electron microscopy and energy dispersive X-ray spectrometer analysis. The result showed that the cationic stabilizer injected by the electrokinetic technique could significantly increase the peat soil’s shear strength. Furthermore, the result showed that the effect of calcium oxide was the highest on the shear strength of peat due to its physico-chemical properties. The shear strength, pH and moisture content of peats across the electrokinetic box also altered depending on the used electrolytes and time.

Uplift Resistance of Buried Pipelines Enhanced by Geogrid

Failure of an oil or gas pipeline due to low uplift resistance of soil has serious economic and environmental consequences; hence, increasing the uplift resistance through soil reinforcement is of interest. The main purpose of this paper is to investigate the possible use of geogrid to enhance the uplift resistance of buried pipelines. For this reason, 11 small-scale laboratory tests were performed. The tests were conducted to investigate the effect of pipe diameter, burial depth, as well as length and number of geogrid layers on the uplift resistance of sandy soils. The experimental results suggest that although pipe diameter and burial depth are directly related to uplift resistance, the direct effect of geogrid incorporation is more pronounced. While Peak Uplift Resistance (PUR) is of interest, findings indicate that the number of geogrid layers does not have a pivotal influence on PUR. In addition, for verification purpose, the PUR of 11 laboratory tests were back analyzed numerically using finite element software PLAXIS 3D TUNNEL. The findings show that numerical and experimental results are in good agreement.

Removal of Suspended Colloids through the Control of Their Zeta Potential

The effect of CaO, Na2SiO3, Al(OH)3, Al2(SO4)3, and CaCl2 on the surface charge and the diffuse double layer (DDL) thickness of a natural tropical peat were investigated in this study. Consequently, the flocculation and coagulation behavior of peat colloids were studied. As result, the thickness of DDL were changed significantly due to the addition of each electrolytes. The compression of the DDL thickness causes a weaker electrostatic repulsion and therefore a higher settlement rate. The surface charge of pure peat was almost zero at pH 3.2. The pH at the isoelectric point was increased by increasing the electrolyte concentration. The resulted flocculation and coagulation behavior of suspended peat in cationic reagents was in contrary with the surface electrical charge characteristics where the Na2SiO3 and the Al2(SO4)3 electrolytes showed the lowest and highest settlement rate, respectively.

Investigating the Effect of Lignosulfonate on Erosion Rate of the Embankments Constructed with Clayey Sand

Internal erosion is known as the most important cause of dam failure after overtopping. It is important to improve the erosion resistance of the erodible soil by selecting an effective technique along with the reasonable costs. To prevent internal erosion of embankment dams the use of chemical stabilizers that reduce the soil erodibility potential is highly recommended. In the present study, a lignin-based chemical, known as lignosulfonate, is used to improve the erodibility of clayey sand specimen. The clayey sand was tested in various hydraulic heads in terms of internal erosion in its natural state as well as when it is mixed with the different percentages of lignosulfonate. The results show that erodibility of collected clayey sand is very high and is dramatically reduced by adding lignosulfonate. Adding 3% of lignosulfonate to clayey sand can reduce the coefficient of soil erosion from 0.01020 to 0.000017. It is also found that the qualitative erodibility of stabilized soil with 3% lignosulfonate is altered from the group of extremely rapid to the group of moderately slow.

Systematic Review of Screw Anchors in Cohesionless Soils

The behavior of a screw anchor under a pull-out load in a cohesionless soil was investigated on the basis of analysis of previous investigations conducted primarily under laboratory conditions. Results of laboratory investigations of the behavior of a screw anchor under a pull-out load in a cohesionless soil are presented. It is indicated that the limiting uplift capacity depends on the shear strength of the cohesionless soil under drained/undrained conditions, and the ratio of the depth of embedment to the thickness of the soil layer.

Prediction of bearing capacity of thin-walled foundation: a simulation approach

In the recent past years, utilization of intelligent models for solving geotechnical problems has received considerable attention. This paper highlights the feasibility of adaptive neuro-fuzzy inference system (ANFIS) for predicting the bearing capacity of thin-walled foundations. For this reason, a data set comprising nearly 150 recorded cases of footing load tests was compiled from literature. Footing width, wall length-to-footing width ratio, internal friction angle, and unit weight of soil were set as inputs of the predictive model of bearing capacity. In addition, a pre-developed artificial neural network (ANN) model was utilized to estimate the bearing capacity of thin-walled foundations. The results recommend the workability of ANFIS in predicting the bearing capacity of thin-walled foundation. The coefficient of determination (R2) results of 0.933 and 0.875, and root mean square error (RMSE) results of 0.075 and 0.048 for training and testing data sets show higher accuracy and efficiency level of ANFIS in estimating bearing capacity of thin-walled spread foundations compared to the ANN model (R2 = 0.710, RMSE = 0.512 for train, R2 = 0.420, RMSE = 0.529 for test). Overall, findings of the study suggest utilization of ANFIS, as a feasible and quick tool, for predicting the bearing capacity of thin-walled spread foundations, though further study is still recommended to enhance the reliability of the proposed model.

Development of new attenuation equation for subduction mechanisms in Malaysia water

The attenuation equation for far field earthquake is important because the earthquake occurring in neighboring countries can be felt in Malaysia. In this study, a new attenuation was generated using the regression method. It was developed to calculate the peak ground acceleration (PGA) onsite (offshore platform). The database consisting of more than 150 PGAs from 9 events of earthquakes recorded by the Seismology Station in Malaysia was used to develop the relationship. In addition, attenuation relationships for subduction mechanisms from previous researchers are then compared with the newly generated ones in this research. The new attenuation equation was also validated and used to calculate the acceleration for far field earthquake in a case study of offshore platform at a Terengganu seaside. The result of PGA from the new generated attenuation relationship was in a good match with previous attenuation equations.

Determination of Reliable Stress and Strain Distributions Along Bored Piles

The present research aims to measure and analyze the most reliable stress and strain distributions transferred in bored piles embedded within multilayer site conditions. Extensive data are summarized to measure changes in the stresses and strains in a bored pile. The effect of weak geological zones on multilayer site conditions can significantly change the design criteria since most of the dominant factors change with depth.

Coagulation of the Suspended Organic Colloids Using the Electroflocculation Technique

Electroflotation is an unconventional separation process owing its name to the bubbles generation method (i.e., electrolysis of the aqueous medium) caused by the hydrogen and hydroxide development. Collecting the colloidal particles in surface water has been a long-term issue all over the world, because of their adverse influence. In the present research, the electroflocculation technique have been use to collect the humus particles throughout the polluted wastewater. The uses of different chemical additives namely, Al2(SO4)3, Al(OH)3, CaCl2, CaO, and Na2SiO3 were also successfully examined and enhanced the electroflocculation technique. Although high negatively surface electrical charge of humus causes difficulties in the conventional flocculation and coagulation technique, it enhances the flocculation process when the electroflocculation techniques have been used. The results of both Jar test and electroflocculation technique are further compared. It can be concluded that the polluted water were fully decontaminated (i.e., all of the suspended colloids through the water were removed) by using the electroflocculation technique. The removal rate after electroflocculation test were 91.8%, 98%, 93.5%, 85.3%, 95.4%, and 94% for neutral, Al2(SO4)3, Al(OH)3, CaCl2, CaO, and Na2SiO3, respectively. While the removal rate after Jar test were 84.8%, 83.79%, 71.44%, 84.83%, 77.09%, and 77.09% for neutral, Al2(SO4)3, Al(OH)3, CaCl2, CaO, and Na2SiO3, respectively.