Perth, Australia
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Ben-Awuah E.,Mining Consultant | Baah-Frempong E.,Geotechnical Engineer | Akayuli C.F.A.,Building and Road Research Institute
Dams and Reservoirs | Year: 2013

Ghana Bauxite Company Ltd operates an open cast bauxite mine at Awaso in the western region of Ghana. As part of its mining activities, a 36 000 m3 water storage facility has been constructed to store water for use in the processing plant. The facility consists of a 4 m high embankment built across a valley on a silty sandy gravel foundation. Seepage forces and pore pressures in the foundation and embankment have raised some stability concerns. The principal objective of this study is to carry out an assessment of the stability of the water storage facility embankment and foundation and propose measures to improve it. The stability assessment procedures include: (a) investigating the geological, geotechnical and engineering properties of the embankment and foundation material, (b) evaluating possible failure factors such as piping, erosion, sliding and seepage; and (c) reviewing operational parameters of the facility. From the qualitative and quantitative assessments, it was concluded that the embankment of the facility was susceptible to failure resulting from inadequate compaction, seepages and overgrown tree roots. The foundation, on the other hand, was found to be susceptible to failure resulting from seepages. Recommendations for improving the embankment integrity include the construction of a toe drain, implementation of a vegetation cover management scheme and documented periodic monitoring. © 2013, Dams and Reservoirs. All rights reserved.

Nazari Afshar J.,Islamic Azad University at Tehran | Hemmati K.,Asilsazan Abniye Co. | Azimi S.,Geotechnical Engineer.
Geotechnical Special Publication | Year: 2016

The use of sand or gravel column which is generally called a stone column is an effective method in modifying soil in order to increasing the bearing capacity or decreasing soil settlement and reduction of soil liquefaction in the earthquake. In stone column construction, usually 15 to 35 percent of weak soil volume is replaced with stone column material. In most equations of stone columns design it is used of the unit cells concept to model granular columns and surrounding soft soil. Laboratory study was conducted to better understand the reinforcing impact of sand column in the fine soil on stress strain behavior and shear strength of soft soil. The laboratory experiment consisted of series of the triaxial tests with a diameter of 100 mm and height of 200 mm.To simulate the effect of soil reinforcing, sand column with diameter of 37.5 and 51 mm was introduced in the center of the soft soil. The results indicate that by using of sand column the shear strength of fine soil has increased substantially. The results also showed increasing the diameter and confining pressure increases the shear strength of the soft soil reinforced by sand column. Details of tests including testing methods and results of the experiments and description of diagrams are provided in the original paper. © ASCE.

Aziz M.,Islamic University | Saleem M.,Geotechnical Engineer | Irfan M.,University of Engineering and Technology Lahore
Geomechanics and Engineering | Year: 2015

The rapid urbanization in Pakistan is creating a shortage of sustainable construction sites with good soil conditions. Attempts have been made to use rice husk ash (RHA) in concrete industry of Pakistan, however, limited literature is available on its potential to improve local soils. This paper presents an experimental study on engineering properties of low and high plastic cohesive soils blended with 0-20% RHA by dry weight of soil. The decrease in plasticity index and shrinkage ratio indicates a reduction in swell potential of RHA treated cohesive soils which is beneficial for problems related to placing pavements and footings on such soils. It is also observed that the increased formation of pozzolanic products within the pore spaces of soil from physicochemical changes transforms RHA treated soils to a compact mass which decreases both total settlement and rate of settlement. A notable increase in friction angle with increase in RHA up to 16% was also observed in direct shear tests. It is concluded that RHA  treatment is a cost-effective and sustainable alternate to deal with problematic local cohesive soils in agro-based developing countries like Pakistan. © 2015 Techno-Press, Ltd

Mccook D.K.,Geotechnical Engineer | Grotrian K.O.,Soil Mechanics Center
Association of State Dam Safety Officials Annual Conference 2010, Dam Safety 2010 | Year: 2010

The late James L. Sherard's published several important articles on the phenomenon of hydraulic fracturing in earthen embankments. The articles were the most comprehensive discussions on this important mechanism of failure of earthen embankments at the time. In some of his studies of hydraulic fracture performed for the NRCS (formerly SCS), he employed finite element computer analyses. Those studies were limited in scope because of the time and expense involved in using computer programs at that time (1970's and 80's). Recently, relatively inexpensive computer programs such as SIGMA/W, combined with the computing capability of modern desktop computers, allow routine use of what were formerly specialized and very time-consuming analyses. This paper includes a discussion of hydraulic fracture and the factors that can affect the susceptibility of an embankment being subjected to hydraulic fracture. It explores the potential uses of finite element programs such as SIGMA/W in evaluating hydraulic fracture in an embankment. The paper compares the results of these SIGMA/W analyses with empirical rules of thumb that have historically been used to assess the potential for hydraulic fracture. Parametric analyses were performed for an idealized abutment section of an embankment to evaluate the effect of assumptions on the predicted hydraulic fracture potential. Parameters that can affect the modulus and Poisson's ratio that are used in the analyses include: (1) the effect of placement water content, (2) plasticity, (3) compressibility of foundation horizons and (4) degree of compaction. Parameters also important to results are (1) abutment geometry, and (2) bedrock profiles. The paper includes a summary of a several parametric analyses together with conclusions of the authors related to these results. The conclusions should be helpful in supplementing the presently available relatively empirical guidelines available to embankment designers. The parametric analyses use the program SIGMA/W to compute the lateral minimum effective stress, σ3, in the profile of the embankment. The results from the analyses allow one to compare the minimum effective lateral stress to the potential hydrostatic heads, thus predicting the potential for hydraulic fracture. Additional discussions are included on available empirical estimates for parameters such as Poisson's ratio and Young's modulus, both of which are important to the finite element results obtained.

Thomas J.,Geotechnical Engineer | Berry A.D.,Principal Maritime Structures Engineer | Terwijn R.J.M.,WorleyParsons Services Pty Ltd
Australian Geomechanics Journal | Year: 2013

This paper describes the design, driveability and deflection monitoring results of a piled cantilever retaining wall at Port Hedland, Western Australia. The retaining wall was required to stabilise an existing access road and conveyor foundations to an existing wharf, prior to the dredging operations for a new export facility in the port. By designing the dredging profile (in front of the retaining wall) as an underwater batter, a cantilever retaining type structure made up of steel tubular piles was found to be feasible. The stability and deflection criteria requirements indicated that some of the retaining wall piles were required to be driven to a toe level of -30 mCD, penetrating through approximately 25 m thick very weak to medium strength rock. General experience of driving piles at Port Hedland area is that the piles are very likely to refuse on a 4 m thick medium strength Conglomerate rock layer starting at about -14 mCD. The piles equipped with external and internal shoe thickening were found to be easier to drive. Measured wall deflections were found to be lower than the initially predicted deflection due to difference in the as-built dredging profile and the assumed design dredging profile. The predicted wall deflection was found to be very similar to the measured deflection when a reanalysis was carried out considering the post dredging as-built batter slope profile. Data from static tension load test carried out on a 610 mm OD and a 1050 mm OD piles for wharfs near the retaining wall is also provided.

Vyse C.H.,Geotechnical Engineer
Dams and Reservoirs | Year: 2013

As a result of leakage along the downstream face of the dam, a section 10 inspection carried out in February 2006 contained a recommendation for a study to be undertaken into the uplift pressures and stability of the concrete gravity dam impounding Llyn Alaw reservoir. The study was subsequently carried out and showed the dam to have inadequate factors of safety for stability during an extreme seismic event. Dwr Cymru Welsh Water awarded a contract to undertake the design and supervision of works to ensure the stability of the structure. The selected method of stabilising the structure was to install 44 no. post-tensioned strand anchors along the length of the dam, vertically through the crest and into the bedrock foundation. This paper describes the stages of the project from feasibility studies and design through to construction of the scheme, which was completed in mid-2013. © 2013, Dams and Reservoirs. All rights reserved.

Thompson A.,Geotechnical Engineer
Dams and Reservoirs | Year: 2013

The Yarrow embankment was built in 1857 and comprises one of two embankments that form the Upper Rivington reservoir. The embankment is approximately 300 m long, 12 m high and is of Pennine type construction with a thin central puddle clay core extending 2 m into a cut-off trench. Following a major leak in 2002 and remedial grouting works, quantitative assessments were carried out by United Utilities (UU) using adapted methodologies referenced in the ‘Risk analysis for dam safety’ document. The assessment identified a significant risk of failure by internal erosion caused by erosion of the clay core within the fissured rock foundation. UU invested in a remedial solution comprising tube-a-manchette (TAM) grouting to supplement the previous 2002 works and methodologies. The grouting was undertaken within 2012 and comprised TAM holes along the crest at 1 mspacing both upstream and downstream of the clay core. During the works significant fracturing and erosion of the bedrock was recorded at various points and was accompanied by significant interconnectivity between the upstream and downstream TAM. The areas of high grout takes indicate a good correlation with the underlying geological conditions and the previous geophysical survey. © 2013, Dams and Reservoirs. All right resedrved.

Ramakrishna A.M.,Hardesty and Hannover LLC | Mankbadi R.R.,Hardesty and Hannover LLC | Tuckman D.S.,Hardesty and Hannover LLC | Guirguis A.,Geotechnical Engineer
Geotechnical and Structural Engineering Congress 2016 - Proceedings of the Joint Geotechnical and Structural Engineering Congress 2016 | Year: 2016

Assessing the potential damage to nearby existing structures from vibrations induced during foundation construction is a complex task. The current practices to prevent damage to existing structures suggest limiting the peak particle velocity (PPV) created during foundation construction activities. Numerous existing structures have suffered damage from foundation construction activities even after full compliance to the current methodology of limiting the PPV. This paper presents an approach to safeguard existing structures adjacent to construction activity through real time dynamic structural evaluation. © ASCE.

Birid K.C.,Geotechnical Engineer
Geotechnical and Geological Engineering | Year: 2016

The unconfined compressive strength (UCS) of rock is a basic parameter for the design of foundations resting on rock. However, it is often very difficult to retrieve intact rock core specimens for the UCS test due to mechanical breaking or natural fracturing of the rock core during the drilling process. In such cases, it becomes obligatory to correlate UCS values based on the point load strength index test results. Correlation between the UCS and the point load strength index test results has been observed to be inconsistent in many instances and hence a need for another such correlation with a relatively higher degree of accuracy to predict UCS values of rock sample has been generated. An endeavor has been made to correlate the UCS value based on the test results of a splitting tensile strength test (STS) by conducting both the tests on various rock samples. Though the UCS test provides compressive strength and the STS test provides tensile strength of a rock, a dimensional analysis technique has been used to correlate these properties. The predicted UCS results are compared with the actual lab UCS test results to validate the mathematical equation thus developed. It has been observed from comparison that this equation can be used to predict UCS values from STS results with a fair degree of accuracy. Thus the Dimensional analysis has established a provisional rule-of-thumb to correlate the UCS with STS test results and further proved that, it is an easy and sufficiently accurate analytical tool. © 2015, Springer International Publishing Switzerland.

Shiau J.,University of Southern Queensland | Buttling S.,Geotechnical Engineer | Sams M.,University of Southern Queensland
Electronic Journal of Geotechnical Engineering | Year: 2015

The current methods of engineering education are under significant pressure to reform. Increasing complaints from industry regarding graduates being inadequately prepared, high failure rates among most engineering programs, and results from a number of engineering education research studies showing problems with traditional teaching methods; this is forcing a push towards different approaches. In an undergraduate geotechnical engineering course at the University of Southern Queensland (USQ), a project-based learning (PBL) assignment has been developed and used for the past three years. It is for slope stability and bearing capacity problems revolving around a real life building collapse in Shanghai in 2009. During this assignment, students are tasked with determining the cause of collapse using computer software, and presenting it in a technical report. Feedback from students has been positive, and samples of this have been provided. This paper describes the development of this assignment, with both the advantages and the challenges. © 2015 EJGE.

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