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Perth, Australia

Trani L.D.O.,Geotechnical Engineer | Trani L.D.O.,University of Wollongong | Indraratna B.,University of Wollongong
Australian Geomechanics Journal | Year: 2010

In rail track environments the loading system is cyclic unlike the monotonie seepage force that usually occurs in embankment dams. The mechanisms of filtration, interface behaviour and time-dependent changes of the drainage and filtration properties occurring within the filter medium require further research to improve the design guidelines. A novel cyclic process simulation filtration apparatus was designed and commissioned at the University of Wollongong, and a standard testing procedure was established. The test apparatus was designed to simulate heavy haul train operations. Key parameters that influence the change in porosity and pore water pressure within the subballast layer under cyclic conditions in rail track environments were identified. Source

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. Source

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. Source

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. Source

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. Source

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