Geotechnical Engineering Works Research Articles

Stabilization Of Marine Clay Using Biomass Silica-Rubber Chips Mixture

Marine clay is found widely along the coastal area and had caused expensive solutions in the construction of coastal highways. Hence, soil stabilization was suggested by some consultant to increase the strength of this soil in order to meet the highway construction requirement and also to achieve the specification for the development. Biomass Silica (BS), particularly the SH85 as a non-traditional stabilisation method, has been gaining more interest from the engineers recently. Rubber chips (RC), derived from waste rubber tyres, are considered ‘green’ element and had been used previously in some geotechnical engineering works. This paper presents the effect of using BS and RC as a mixture (BS-RC mixture), to increase the strength of marine clay for highway construction. Samples of marine clay, obtained from the West Coast Expressway project at Teluk Intan, Perak, were oven dried and grind to fine-grained sized. The marine clay was mixed with 9 % by weight proportion of BS- RC; that were 8%-l% and 7%-2%, respectively. For comparison purposes the result of BS-RC was compared to the result of stabilization by using 9% BS only. Laboratory tests were then carried out to determine the Atterberg limits and compaction characteristics of the untreated and treated marine clay. The Unconfined Compressive Strength (UCS) of the untreated and treated marine clays, compacted at the optimum moisture content was later obtained. The treated marine clay was tested at 0, 3 and 7 days curing periods. The results show that the Plasticity Index of BS-RC treated marine clay was lower than the untreated marine clay. From the UCS test results, it is shown that BS-RC mixtures had significantly improved the strength of marine clay. With the same percentage of 9% BS-RC, the increased of BS from 7% to 8% increased the UCS further to about six times more than untreated marine clay soils in 7 days curing period. The strength gained by using BS-RC at 8%-1% is slightly below the strength by using 9% BS only. From the experimental results, it is shown that BS, in the form of SH85, admixed with rubber chips could significantly improve the strength of marine clay soils.

PROPERTIES OF COAL BOTTOM ASH FROM POWER PLANTS IN MALAYSIA AND ITS SUITABILITY AS GEOTECHNICAL ENGINEERING MATERIAL

Coal is one of the world’s most important sources of energy, fuelling almost 40% of electricity worldwide. Some power plants in Malaysia use coal as a raw material in generating the electricity since the year 1988. During the burning process of coal for the electricity generation, coal waste is produced which includes coal ash in the fraction of about 75-85 % Fly Ash (FA) and 15-25 % Bottom Ash (BA). The FA has been widely used in the cement industry but the BA is still not largely utilised in Malaysia. This might be due to the fears on the environmental hazard that might be occurred as a result of possible leaching of metal from the BA to the ground water. Research on the possible usage of BA in Geotechnical Engineering work has been taken place in Universiti Teknologi Malaysia since 2008, in collaboration with the Tanjung Bin, Sultan Salahuddin Abdul Aziz Shah (or Kapar) and Sultan Azlan Shah (or Manjung) power plants in Johor, Selangor and Perak, respectively. This paper presents the physical, morphological, mineralogical, chemical and mechanical properties of BA and explores the possibility of using BA as alternative materials in Geotechnical Engineering works. Analysis of the results from the laboratory and physical model tests show a huge potential of utilising this BA.

Shear Strength of a Crushed Sandstone-Mudstone Particle Mixture

The present study focuses on the shear strength of a crushed sandstone-mudstone particle mixture. The mixture is widely used as a main filling material in many geotechnical engineering works. In order to investigate the shear strength of the mixture, triaxial tests under different confining pressures in laboratory are performed for 108 specimens with different dry densities and water contents. The dry density of the specimens ranges from 1.80 to 2.10 g/cm3, and the water content from 4.00 to 9.00 % and to saturation. In the tests, four confining pressures, which are 100, 200, 300 and 400 kPa, are applied. The testing results indicate that the angle of shearing resistance of the mixture in unsaturated state ranges from 16.90 to 32.98°. The angle of shearing resistance is generally decreasing with the increase of the confining pressure. With the increase of the dry density, the angle of shearing resistance increases. The angle is generally increasing then decreases as a parabola with the increase of the water content. The wetting may decrease the value of the angle about 0.4 to 2.7°.

The Strength of Fly Ash-Bottom Ash (FA-BA) Mixtures as Backfill Material in Ground Improvement Works

In Malaysia, coal has been used as a raw material to generate electricity since 1988. In the past, most of the wastage of coal burning especially the bottom ash was not managed properly as it was dumped in the waste pond and accumulated drastically. This research has been conducted to explore the physical characteristic and geotechnical properties of fly ash-bottom ash (FA-BA) mixtures that consist of 30% FA, 50% FA, 70% FA and 90% FA by weight. The physical characteristics, that include the specific gravity, particle size distribution and compaction, were tested for each mixture without any curing. However, the geotechnical properties of the mixtures that include the permeability and shear strength had been studied at various curing periods (0, 14 and 28 days) to review the effect of time on the geotechnical properties of the mixtures. The results show that mixtures with higher FA composition have lower value of specific gravity, well-graded, and need less moisture to be compacted efficiently compared to those mixtures with lower FA composition. The results also show that mixtures with higher FA composition have less drainage characteristics but can be improved by prolonging the curing period. The maximum shear strength was obtained at mixture with 50%FA and the value increased with curing periods. The friction angle obtained ranged from 270 to 370. It is also found that the mixtures with lower FA composition are more compressible compared to the mixtures with higher FA composition. The results obtained could be used by others to determine the suitability of different FA-BA mixtures for various usage in Geotechnical Engineering work such as for soil improvement work in weak soils or as backfill materials in embankment construction.

Design Engineering to Control Geological Environmental Problems of Limestone Mine in Fengshan, Guangxi

Geo-environmental treatment projects had not been implemented in many old mines of China. Those mines environment has got increasingly deteriorated. So the government provides specialized policies and funding to solve the environmental problems of those mines. Based on the characteristics of the geological environmental treatment projects of old mines, the paper puts forward the principle and index of the treatment projects design and applies in the design of Fengshan limestone mine, Guangxi. It indicated that: (1)The geological environment problems are complex and diverse, and the treatment projects involve a multi-disciplinary cross which are environmental geology, ecology geology, geotechnical engineering, environmental engineering and landscape works. It needs to consider the follow key indicators: Geo-environment problems, Feasibility, Benefit, and social demand. (2) the limestone mine in FengShan is high 134m, and there had happened a collapse which had 2.1×104 m3, and killed 6 people. The geo-environment problems include rockfall, rock collapse, land and vegetation destruction, and landscape damage. The mine local in the Leye-Fengshan International Geological Park in Guangxi, the requests for travel security and sight-viewing environment are extremely high. Therefore, drainage, anchoring, rockfalls platforms and rock carvings would be implemented for the purpose of transforming the mine into a sight spot in the park.(3) The treatment projects eliminate the geo-hazard and build the world-class carving attractions reflect the benefit of the project management from the environment, economy and society aspects.

Compressive and Tensile Strength of Artificially Cemented Dune Sand

Artificial cementation is a technique commonly used to improve the mechanical properties of soils for use in geotechnical engineering works, because it often provides economic and environmental advantages. In order to study the factors that influence the behavior of cemented dune sand from Natal, series of unconfined compression and splitting tension tests were performed. These tests showed that increasing the cement content and decreasing void ratio are effective ways to improve compressive strength. The same applies to tensile splitting strength. It was also established that both unconfined compressive and splitting tensile strengths can be related to a quotient between volume of void-space and cement content.

Installation effects of auger cast-in-place piles

Since their introduction in Europe and North America some 50years ago, auger cast-in-place piles (ACIP) have become increasingly popular all over the world. These piles offer considerable environmental advantages during construction including minimal vibration, and low noise beside their high productivity. The most severe limitation of the ACIP is its sensitivity to operator performance, which can lead to a pile of poor integrity or inconsistent quality. Thus the improper use of ACIP equipment can result in piles containing defects or can cause instability of nearby structures. Three case studies are presented and discussed in an effort to illustrate learned lessons. First case study highlights the misuse of ACIP equipment leading to unreliable defective pile foundations. Second and third case studies show the adverse effects of installing ACIP on the stability of nearby structures. The study revealed that it is essential to employ a clever pile crew during the installation of ACIP to observe, interpret, and take corrective actions for unusual situations. The authorities worldwide should oblige pile contractors to employ only experienced and qualified workers in charge of geotechnical engineering works. Tender documents should include precise clauses related to the technological factors affecting the quality of ACIP. Unfavorable side effects of installing ACIP in saturated loose and medium sand can cause tilt of adjacent existing structures; even they are on either shallow or deep foundations. A row of micro-piles and/or soil grouting adjacent to the existing buildings were successfully used to reduce the adverse effects of ACIP. Implementation of different codes on the results of pile loading tests produced different pile working loads. Therefore tender documents should specify the code upon which interpreting the pile test results. At the meantime the geotechnical engineer should implement his experience and judgment during application of the specified code. Finally this work indicates that the outcome prediction of ACIP may deviate from the actual performance.

Laboratory Research on EPS Blocks Used in Geotechnical Engineering

Geosynthetic geofoam has a cellular structure made of expanded polystyrene (EPS) and has been used as a lightweight material for geotechnical use in embankments, bridges seat, base and sub-base of roads pavements and infrastructure protection applications. This paper presents research data on EPS laboratory tests aiming to characterize Brazilian EPS for geotechnical use. The mechanical tests comprised unconfined axial compression (with variation of temperature, specimens dimensions and rates of deformation velocity), interface shear friction (EPS – EPS) and creep under compressive load. A simple loss weight test by mice attack was also conducted in an attempt to quantify the damage in samples of EPS by biological attack. Samples of 10 kg/m3 , 14.5 kg/m3 , 17 kg/m3 , 20 kg/m3 , 30 kg/m3 and 40 kg/m3 densities with virgin material and 10 kg/m3 with recycled material were used. The results have shown that EPS has a great strength in compression and creep solicitation and high interface friction strength despite its very low density, and good geotechnical properties for applications in geotechnical engineering works. In the weight loss test it was found that the mice only attach the material mainly for a specific situation.

Estimating shear wave velocity of soil deposits using polynomial neural networks: Application to liquefaction

Geophysical and geotechnical field investigations have introduced several techniques to measure in-situ shear wave velocity of soils. However, there are some difficulties for the easy and economical use of these techniques in the routine geotechnical engineering works. For the soil deposits, researchers have developed correlations between shear wave velocity and SPT-N values. In the present study, a new database containing the measured shear wave velocity of soil deposits have been compiled from the previously published studies. Using polynomial neural network (PNN), a new correlation has been subsequently developed for the prediction of shear wave velocity. The developed relationship shows an acceptable performance compared with the available relationships. Three examples are then presented to confirm accuracy and applicability of the proposed equation in the field of liquefaction potential assessment.

Morphological and Strength Properties of Tanjung Bin Coal Ash Mixtures for applied in Geotechnical Engineering Work

In Malaysia, coal has been used as a raw material to generate electricity since 1988. In the past, most of the wastage of coal burning especially the bottom ash was not managed properly as it was dumped in the waste pond and accumulated drastically.This paper focuses on some properties of coal ash mixtures (fly ash and bottom ash mixtures) from Tanjung Bin power plant. The characteristics studied were morphological properties, compaction behaviour and strength properties. Strength properties of coal ash mixtures are carried out by conducting direct shear test and unconfined compression test. Besides, morphology and mineralogy of coal ash mixtures are studied using scanning electron microscope (SEM) and x-ray diffraction (XRD). The coal ash mixtures were compacted at 95% of maximum dry density, sealed and cured for 0, 14, and 28 days before they were analysed for shear strength, morphological and mineralogical analyses. The shear strength of coal ash mixtures varied depending on the fly ash compositions. The maximum shear strength was obtained at mixture with 50%FA: 50%BA and the value increased with curing periods. The friction angle obtained ranged from 27° to 37°. Morphological analysis showed that the number of irregular shaped particles increased confirming change in material type with curing period. From mineralogical analysis, the crystalline compounds present in Tanjung Bin coal ash were Mullite, Quartz, Calcium Phosphide, Calcite, Cristobalite and Hematite. It can be concluded that the coal ash mixtures can advantageously be applied in the construction of embankments, roads, reclamation and fill behind retaining structures.

Tailings-nonwoven geotextile filter compatibility in mining applications

Nonwoven geotextiles have been commonly used in filtration and drainage of geotechnical engineering works. This paper presents a study on the use of such materials in drainage and filtration systems of tailings dams. Different combinations of tailings and geotextiles were submitted to gradient ratio (GR) tests under confinement in the laboratory with varying values of stress levels and hydraulic gradients. The results of GR tests under confining stresses up to 2000 kPa are presented and discussed. The dimensions of the tailings particles entrapped in the geotextile specimens and those that piped through the geotextile were also assessed. Geotextile specimens from the drainage system of a tailings dam were exhumed for analyses, as part of the research programme. The results obtained showed that stress levels and the hydraulic gradients used in the tests influenced the behaviour of the system. Physical and microscopic analyses of the specimens tested showed greater geotextile impregnation by tailings particles in the field than in the laboratory. The overall performance of the geotextiles tested under laboratory conditions was satisfactory. However, in the field segregation of tailings particles and transport of fines in suspension can subject the filter to more complex and severe clogging mechanisms, not properly simulated in current standard testing procedures.

Controlling suction by the vapour equilibrium technique at different temperatures and its application in determining the water retention properties of MX80 clay

Problems related to unsaturated soils are frequently encountered in geotechnical or environmental engineering works. In most cases, for simplicity, one can study the problems by considering the suction effects on volume change or shear strength under isothermal conditions. Often, under these conditions, a temperature-independent water retention curve is considered in the analysis — obviously a simplification. When the temperature changes are too significant to be ignored, it is necessary to account for the thermal effects. This note presents a method for controlling suction with the vapour equilibrium technique at different temperatures. First, calibration of various saturated saline solutions was carried out at temperatures ranging from 20 °C to 60 °C. A mirror psychrometer was used to measure relative humidity generated by saturated saline solutions at different temperatures. The results obtained were in good agreement with the data from the literature. This information was then used to determine the water retention properties of MX80 clay, which showed that the retention curve shifts downward with increasing temperature.Key words: vapour equilibrium technique, hygrometer, water retention curve, temperature effects, compacted bentonite.

Channel Tunnel Rail Link section 1: ground engineering

Some of the most innovative engineering design on the first section of the £5·2 billion Channel Tunnel Rail Link related to groundworks—ranging from dynamic analysis of trackbeds and pile slabs to dry soil mixing techniques and 3D groundwater modelling. This paper provides a brief overview of the geotechnical engineering work on section 1 and explains how the need to reduce design risk to a minimum resulted in valuable new industry guidance.

Channel Tunnel Rail Link section 1: ground engineering

Some of the most innovative engineering design on the first section of the £5·2 billion Channel Tunnel Rail Link related to groundworks—ranging from dynamic analysis of trackbeds and pile slabs to dry soil mixing techniques and 3D groundwater modelling. This paper provides a brief overview of the geotechnical engineering work on section 1 and explains how the need to reduce design risk to a minimum resulted in valuable new industry guidance.

Foundation design for the refloat of the Maureen steel gravity platform

The Maureen Oil Field, located in the UK sector of the North Sea, was developed in the early 1980s, with the installation of the world's largest steel gravity platform, together with the installation of an export pipeline to an offshore concrete articulated loading column. Production in the field ceased in October 1999, and the facilities at the Maureen location were removed in the summer of 2001 as part of the decommissioning process. The largest element for removal and decommissioning was the steel gravity platform of about 1100 MN (110 000 t). This paper describes all the geotechnical engineering works, associated with the hydraulic skirt extraction/jacking of the gravity platform from the seabed, which were executed prior to the refloat and tow of the platform to deep water inshore moorings, together with a summary of results from the actual skirt extraction/jacking process, which was executed in June 2001.

Airborne electromagnetic bathymetry

An experimental airborne electromagnetic (AEM) survey was carried out in the Cape Cod Bay area to investigate the potential of extracting bathymetric information over a shallow ocean. A commercially available Dighem III AEM System was used for the survey without any significant modification. The helicopter-borne system operated at 385 Hz and 7200 Hz, both in horizontal coplanar configurations. A concurrent ground truth survey included extensive included acoustic profiles, as well as spot water conductivity measurements. Because of the lack of knowledge about the absolute system calibration, a postsurvey calibration was made for each flight line, using a small portion of AEM data to derive the zero-level signal, amplitude, and phase calibration factors for each coil pair. The interpreted bathymetric profiles show excellent agreements with corresponding acoustic depth profiles up to one skin depth (possibly more) of the source frequency. It is envisioned that with further improvements in hardware and software, the bathymetric resolution may extend beyond the skin depth. AEM data can also produce (as by-products) conductivity profiles of both seawater and bottom sediments that may find potential applications in various offshore geotechnical engineering works.

Geotechnical engineering work for the restoration of the Temple of Apollo Epicurius, Bassae : Costopoulos, S D Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug-10 Sept 1987V1, p327–330. Publ Rotterdam: A A Balkema, 1987

Geotechnical engineering work for the restoration of the Temple of Apollo Epicurius, Bassae : Costopoulos, S D Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug-10 Sept 1987V1, p327–330. Publ Rotterdam: A A Balkema, 1987

Geotextiles in India

Applications of geotextiles in civil engineering have been successfully developed and offer benefits in terms of economics, durability and p performance. Geotextiles play an important role in geotechnical engineering works, especially highways and railroads, reinforced soil, stabilisation of soil or rock slopes, drainage control, embankments and dams, tunnel constructions, reservoirs, coastal engineering and canals. This paper mainly gives information about the development and use of geotextiles in India.