An Investigation of an Embankment Failure in Soft Clay

A number of embankment founded on soft clays have become unstable during construction of a major highway project in Malaysia. One of the embankment was back analysed based on its geometry before the failure. Measured in-situ vane shear strength was used in total stress analysis to determine the factor of safety at failure. Performance of the soft clay subsoil with regards to vertical and horizontal displacements, and piezometric response, when the failure was imminent is also described

Pile Embankment on Soft Clay: Comparison Between Model and Field Performance

The paper describes the performance of a full scale pile embankment on soft clay foundation which has been built and instrumented in Malaysia. Reference is made to a parallel design study carried out using centrifuge modelling technique

Effects of Cyclic Test in Decreasing Damages to Structures and Roads on Gypsum Soils

Fine gypsum soils, when saturated and loaded, because of their high porosity, have large settlements. Compaction of the soil and removal of the load causes the soil to swell. These properties of gypsum soils cause many problems for structures built on them. For instance unsymmetrical settlement, uneven ground floor and cracks in façade are some of the problems. Likewise in road engineering, swelling of this type of soil located under the asphalt after absorbing water is one of it most important problem. So realizing and identifying the behavior of gypsum soils and effort in finding solutions for decreasing the amount of settlement and swelling are the main objectives of this study. The soil samples were from the City of Mashhad, which is the second largest city in Iran. These soils naturally contain high amount gypsum and hence have a special behavior. In this study, samples with different amount of gypsum were gathered and classified to seven sample groups. Preliminary tests done showed that the increase in the amount gypsum causes the soil plasticity index and unit weight to decrease, which in turn increases settlement. In order to investigate the influence of degree of compaction, all samples were compacted with different unit weight and the swelling potential and swelling pressures were measured after saturation. The results show that with increasing unit weight and amount of gypsum, the soil swelling potential increases. Cycles of wetting and drying and also cycles of loading and unloading were performed to investigate their influence on the gypsum soil

Application of Geophysical Techniques for 3D Geohazard Mapping to Delineate Cavities and Potential Sinkholes in the Northern Part of Kuala Lumpur, Malaysia

This work describes the application of the electrical resistivity (ER) method to delineating subsurface structures and cavities in Kuala Lumpur Limestone within the Batu Cave area of Selangor Darul Ehsan, Malaysia. In all, 17 ER profiles were measured by using a Wenner electrode configuration with 2 m spacing. The field survey was accompanied by laboratory work, which involves taking resistivity measurements of rock, soil, and water samples taken from the field to obtain the formation factor. The relationship between resistivity and the formation factor and porosity for all the samples was established. The porosity values were plotted and contoured. A 2-dimensional and 3-dimensional representation of the subsurface topography of the area was prepared through use of commercial computer software. The results show the presence of cavities and sinkholes in some parts of the study area. This work could help engineers and environmental managers by providing the information necessary to produce a sustainable management plan in order to prevent catastrophic collapses of structures and other related geohazard problems

Analysis of Longitudinal Cracks in Crest of Doroodzan Dam

Doroodzan earth dam is located in 85 km north western of Shiraz. Because of the unusual seepage flow in the left abutment, in 1992 an impermeable vane was grouted there. Soon after that, obvious changes in water Table profile occurred and simultaneously some incremental number of cracks in left abutment crest was appeared. In present study seepage through left abutment has been analyzed by considering water Table changes. Different phreatic surface line was carried out from recent 20 years in order to find the most vulnerable one. In addition, Seismic loading used to get proper perception of seismic stability. First, by gathering data from piezometric head through the left abutment, most critical phreatic line in left abutment section of dam was observed. Then by using present phreatic surface in numerical modeling of critical section in the left abutment of dam, long term stability of downstream in different situation were calculated. The conditions were changed by increasing the saturation zone and the time which saturation zone stay through the downstream body

Three point bending flexural strength of cement treated tropical marine soil reinforced by lime treated natural fiber

Marine soil in the Selangor State of Malaysia was characterized with respect to its engineering properties as pavement layer in road constructions. Samples were collected from North Klang area in Selangor, Malaysia and subjected to physico-chemical, mineralogical and geotechnical analyses. Quick lime or calcium oxide (CaO) treated coconut fibers were introduced to soil cement mixture to enhance the flexural strength of tropical marine soil. Three point bending tests were carried out on treated samples after 7, 14 and 28 days respectively. The tests results showed improvements in the flexural performance of the mixture as it could be seen by the increase in the flexural strength, Young’s modulus and the toughness index especially when the treated fibers were incorporated into the mixture. It was found that, the bond strength and interaction between treated fibers and soil was the dominant mechanism controlling the reinforcement benefit. It can be concluded that, the application of the CaO treated coconut fiber reinforced cement treated marine clay from Peninsular Malaysia is useful both in strength and ductility as pavement layer in road constructions

The effect of size and replacement content of nanosilica on strength development of cement treated residual soil

In this study, effects of size and replacement content of nanosilica on physical, chemical, and microstructural characteristics of cemented residual soil were investigated. Accordingly, UCS and electrical resistivity tests were conducted on cemented specimens with replacement contents of 0.2%–1% nanosilica of 15 and 80 nm at 7, 14 and 28 days. XRD, Zeta potential, CEC, FTIR, and SEM tests were performed to identify chemical and microstructural changes over time. The results showed that smaller size nanosilica had an accelerated influence on samples while nanosilica of larger size was more effective at ages after 14 days of curing

Sugars from sago frond as prebiotic substrate to enhance the growth of Lactococcus lactis IO-1 and production of L-lactic acid

Sago palm is often discredited for exhibiting long maturity period and barrenness of pre-harvest products, which restrain its potentials as an alternative and eternal starch provider. The use of sago fronds to produce prebiotic and fermentable sugars from pruned palms and fronds discarded upon harvesting is a possible enterprise to provide income for the cash-strapped sago farmers while waiting for the sago trunks to be harvestable. Dried sago frond powder coupled with the cellulolytic enzyme and incubated for 48 hours, producing a maximum recovery of cellobiose at 25%. This is of great advantage in reducing the cost of large-scale processes since the yield and productivity from SFS is comparable to the Standard Medium and SFS amended with yeast extract at 0.85g/g and 85%, respectively. Meanwhile, the composition of cellobiose as main sugar component increase the viability of the Lactococcus lactis I0- 1 by prolong the lifespan of the cell by perform as slow release carbon source, in fact, cellobiose was protected by β (1-4) glycosidic bond made it consumable to specific probiotic in human digestive system conceive that cellobiose as potential prebiotic component for human. Clearly, the use of sago frond is highly economical and sustainable as the raw material for the manufacturing of fermentable sugars and subsequently as the sustainable substrate for large-scale production of L-lactic acid