Model test on the axial capacity of displacement ribbed piles

The capacity, hence the load-settlement behaviour of a pile is governed by the collective behaviour of the base and shaft. It is highly desirable, sustainable and economical to accommodate the increasing demand for deeper and wider foundations through the use of higher capacity piles. This research investigated the performance of preformed displacement ribbed piles in a unit gravity model test. Four tests were carried out to replicate the constant rate of penetration (CRP) test in the field. Two lengths corresponding to short and long piles for each of plain and ribbed piles were employed. Compacted Kaolin S300 type was employed as the model soil. The failure load of the piles was determined using six different methods. An increased capacity of 32% and 20% was obtained in the short and long ribbed piles, respectively. Also, it was observed that the closer the distance between the ribs, the higher the capacity produced for equal number of ribs. The ribbed piles gave higher capacities through the increase in their shaft capacity which is associated with the presence of ribs along their lengths. An increase in the axial capacity of displacement piles can be attained by modifying the profile of the pile shaft through the use of ribs

Correlation between Liquidity Index (LI) & unconfined compressive strength of stabilized silty clay

This paper presents the correlation between Liquidity Index (LI) and Unconfined Compressive Strength (UCS) of stabilized silty clay of Permas Jaya Distric, Johor State of Malaysia. In this study, a number of 9 samples of soil cement were prepared under various cement and moisture contents and cured for 7-days. Ordinary Portland Cement (OPC) of 7% and 13% of soil weight is added to the soil with different level of moisture content based on the Optimum Moisture Content (OMC) value from the compaction test (0.9, 1.0 and 1.1 from OMC) in order to study the effect of moisture content on the compaction characteristic and compressive strength. The result from the compaction test found that the highest and optimum maximum dry density (MDD) was obtained from 7% of cement content. The UCS increases as the cement content increases. Based on the LI and UCS relationship, the strength reached a minimum value of subgrade design strength for low volume road (0.8MPa) when the range of the LI is -0.27 and -0.15 at 7% of cement content

Enhancing the bearing capacity of rigid footing using limited life kenaf geotextile reinforcement

This research focuses on soft clay improvement by using Kenaf textile as a natural geotextile reinforcement. A series of small-scale laboratory tests were conducted to study the impact of the geotextile reinforcement depth, d, the vertical spacing between reinforcement, S and the number of reinfor- cement layers, N on the bearing capacity of the soil model. The test results were verified using the numerical simulation by PLAXIS 2D. In this study, the influence factors included four different d/B ratios of 0.25, 0.5, 0.75 and 1.0; three different S/B ratios of 0.25, 0.5 and 0.75, and a different number of reinforcement layers, N from 1 to 4 were investigated where B is the footing width. The results clearly showed that the bearing capacity of rigid footings was significantly improved with the Kenaf geotextile layers in the kaolin. The measured and predicted bearing capacity results were in good agreement. The optimum d/B ratio and S/B ratio, which resulted in the maximum ultimate bearing capacity of the Kenaf-reinforced model ground were about 0.25 and 0.25, respectively. The optimum N was 3, i.e., the bearing capacity insignificantly improved even with N > 3

Numerical Modeling of Encased Stone Columns Supporting Embankments on Sabkha Soil

The present research work is concerned with the construction of road embankments on a specific soil called Sabkha in Algeria. This soil is not only soft and very humid during the flooding seasons but also has frequent small areas of very soft soil which we here call Locally Weak Zones (LWZ). LWZ is characterized by low strength and high compressibility. The paper presents the results of two-dimensional axisymmetric numerical analyze that were carried out using PLAXIS 2D 2017, for the modeling of an embankment supported by stone columns on Sabkha soil. The study focuses on the evaluation of the maximum bulging of the stone column and on the settlement of the embankment. It has been demonstrated that Ordinary Stone Columns (OSC) were ineffective due to excessive bulging (221.16 mm) caused by the lack of lateral pressure. On the other hand, the Encased Stone Columns (ESC) showed good behavior, namely a much reduced bulging (42.09 mm) and a reasonable settlement (0.962 m vs. 1.560 m for an OSC) so that it is possible to build safe very high embankments. The numerical analysis also shows that the length of the encasement should just be greater than the depth of the LWZ. Besides, an extensive parametric study was conducted to investigate the effects of the variations of embankment height, stiffness of geosynthetic, the depth of the locally weak zone, area replacement ratio (ARR), and the stone column friction angle, on the performance of the (ESC) - embankment composite in (LWZ). Some important guidelines for selecting the ideal encased stone column (ESC) to support embankments on over locally weak zone were established through this numerical study

Time-dependent physicochemical characteristics of Malaysian residual soil stabilized with magnesium chloride solution

The effects of non-traditional additives on the geotechnical properties of tropical soils have been the subject of investigation in recent years. This study investigates the strength development and micro-structural characteristics of tropical residual soil stabilized with magnesium chloride (MgCl2) solution. Unconfined compression strength (UCS) and standard direct shear tests were used to assess the strength and shear properties of the stabilized soil. In addition, the micro-structural characteristics of untreated and stabilized soil were discussed using various spectroscopic and microscopic techniques such as X-ray diffractometry (XRD), energy-dispersive X-ray spectrometry (EDAX), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer, Emmett and Teller (BET) surface area analysis. From the engineering point of view, the results indicated that the strength of MgCl2-stabilized soil improved noticeably. The degree of improvement was approximately two times stronger than natural soil after a 7-day curing period. The results also concluded the use of 5 % of MgCl2 by dry weight of soil as the optimum amount for stabilization of the selected soil. In addition, the micro-structural study revealed that the stabilization process modified the porous network of the soil. The pores of the soils had been filled by the newly formed crystalline compounds known as magnesium aluminate hydrate (M-A-H).Ministry of Education Malaysia under the Fundamental Research Grant (FRGS) (R.J130000.7822.4F658); Universiti Teknologi Malaysia (UTM); Construction Research Centre UT

Numerical and physical modelling of Kaolin as backfill material for polymer concrete retaining wall

The failure mechanism of backfill material for retaining wall was studied by performing a numerical analysis using the finite element method. Kaolin is used as backfill material and retaining wall is constructed by Polymer Concrete. The laboratory data of an instrumented cantilever retaining wall are reexamined to confirm an experimental working hypothesis. The obtained laboratory data are the backfill settlement and horizontal displacement of the wall. The observed response demonstrates the backfill settlement and displacement of the retaining wall from the start to completion of loading. In conclusion, numerical modelling results based on computer programming by ABAQUS confirms the experimental results of the physical modellin

Deformation model of deep soil mixing using finite element method

Soil improvement is required to decrease the construction impact on the adjacent underground structures, when a deep excavation is carried out. Deep soil mixing (DSM) is a common method to control deformation caused by deep excavation. This method is an in situ soil mixing technology that mixes existing soil with cementitious materials. This paper presents a numerical modeling of DSM columns, which was conducted to compare the affected zone achieved by installing two different partially penetrated soil-cement columns using a small scale physical modelling. Test procedure and the finite element analysis that verify ground displacement patterns were described. The finite element method (FEM) was focused on the plane strain numerical modeling in ABAQUS. It was found that higher numbers of piles increase the effect of soil deformation where it will extend the soil in much deeper depth before it fails

Development of slope monitoring device using accelerometer

There are many types of instruments that have been used for monitoring the high risk slopes as a precaution to prevent the loss of lives. Unfortunately, there is no such works of installation slope monitoring instrumentation as detectors and preventive actions before the slope failure. Automatic Wireless Accelerometer Monitoring System (AWAM) is a new device of monitoring system using accelerometer, introduced in this research. It is more efficient than conventional techniques and less expensive. The application and operation of this system does not interrupted by physical obstacles, different climate conditions, and the construction works at site. In addition, no contact is required since the accelerometers are installed on the slope. Consequently, geomorphology limitations are not considered as limitations of the system operation. This paper discusses the sensor database system by AWAM and shows the effectiveness of the device to monitor slope failures and act as a warning sign. It was presented in two parts; the first part consisted of the physical modelling calibration test from sensor database system (AWAM device) and from load cell test while the second part discussed on the numerical model simulated by using software (Slope/W and LimitState) and the data from vane shear test. The AWAM device can be used as a monitoring system to detect soil movements. However, accelerometer was able to give AWAM’s readings if the device is moving in tilting modes

Bearing capacity of sandy soil treated by Kenaf fibre geotextile

Bio-based materials are widely used recently in order to introduce a more sustainable construction material. Kenaf is a type of bio-based material that can be easily obtained in a tropical country, which could be a potential material to be utilised as a geotextile material because it has good tensile strength. The geotextile could be used to improve the bearing capacity of a loose soil. This paper presents a series of small-scale physical modelling tests to investigate the bearing capacity performance of Kenaf fibre geotextile laid on and inside the sand layer. A rigid footing was used to replicate a strip footing during the loading test, and sand was prepared based on 50% of relative density in a rigid testing chamber for ground model preparation. In order to treat the soil, Kenaf fibre geotextile was laid at four difference locations which are on the soil surface and underneath the ground model surface at 50, 75 and 100 mm deep. It was found that the usage of the Kenaf fibre geotextile has improved the bearing capacity of the sandy soil up to 414.9% as compared to untreated soil. It was also found that the depth of the Kenaf fibre geotextile treated into the soil also affects the soil performance. © 2017, Springer-Verlag GmbH Germany

Control of microbiologically influenced corrosion using ultraviolet radiation

Baram Delta Operation had been producing oil and gas since 1960’s and serious pipelines failure was reported in the year of 2005. The final investigation has concluded that one of the species of bacteria that has been identified to cause microbiologically influenced corrosion, specifically known as sulfate reducing bacteria (SRB) was found to be one of the potential contributing factors to the incidents. This work investigates the potential use of ultraviolet (UV) radiation to inhibit the SRB consortium that was cultivated from the crude oil in one of the main trunk lines at Baram Delta Operation, Sarawak, Malaysia. The impact of UV exposure to bio-corrosion conditions on carbon steel coupon in certain samples for 28 days was discussed in this study. The samples were exposed to UV radiation based on variations of parameters, namely: time of UV exposure; and power of UV lamp. The significant changes on the amount of turbidity reading and metal loss of the steel coupon were recorded before and after experiment. The results showed that SRB growth has reduced rapidly for almost 90% after the UV exposure for both parameters as compared to the abiotic samples. Metal loss values were also decreased in certain exposure condition. Additionally, field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS) was performed to observe the biofilm layer formed on the metal surface after its exposure to SRB. The evidence suggested that the efficiency of UV treatment against SRB growth could be influenced by the particular factors studied