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Trumbull, CT, United States

Baxter C.D.P.,University of Rhode Island | Sharma M.S.R.,Ocean and Coastal Consultants Inc.
Geotechnical Special Publication | Year: 2012

There is increasing use of small strain shear modulus, calculated from the shear wave velocity (vs), in geotechnical site characterization, analysis and design. Shear wave velocity is significantly influenced by stress state of the soil among many other parameters. In this paper the effect of shear stress on shear wave velocity of weakly cemented sands during drained and undrained triaxial compression is evaluated. The results showed that shear wave velocity during drained shear is dependent on σ'1 and during undrained shear it is dependent on σ'3. During drained compression, vs increased with σ'1 up to a principal stress ratio of 6-12, depending on the level of cementation and beyond this stress ratio vs decreased significantly even as σ'1 continued to increase up to failure. It is hypothesized that the observed behavior of vs during shear could be used as a precursor to failure for projects involving sensitive or structured soils. © 2012 American Society of Civil Engineers. Source

Weggel J.R.,Drexel University | Dortch J.,Drexel University | Gaffney D.,Ocean and Coastal Consultants Inc.
Geotextiles and Geomembranes | Year: 2011

In order to investigate the use of geotextile bags for dewatering slurries, an analytical model for a fluid draining from a hanging geotextile bag is derived and presented in dimensionless form. A data analysis procedure is proposed. Experimental results using water as the fluid with specially constructed geotextile bags are compared with the model and show excellent agreement. The model is applied to data for slurry-filled bags and used to determine the overall permittivity of a hanging bag dewatering system and the fraction of the bag's volume drained as fluid. © 2010 Elsevier Ltd. Source

Ludwig M.,Ocean and Coastal Consultants Inc. | Clarke D.,U.S. Army
Coastal Engineering Practice - Proceedings of the 2011 Conference on Coastal Engineering Practice | Year: 2011

This paper discusses innovative environmental compensation used in port development. Sustainable development can be complicated by costly regulatory requirements. These requirements stem from the National Environmental Policy (NEPA) and Clean Water Acts (CWA). Federal and state NEPA and CWA versions require identification and evaluation of adverse impacts and methods to avoid, minimize or mitigate them. While some projects find political support helpful in addressing environmental and social conflicts more frequently, designs are used that are environmentally compatible but may limit development. Environmental issues are routinely related to physical attributes that control a site's ecological importance and sensitivity. Taking advantage of local physical attributes to re-nature sites and avoiding maintenance often provides missing but significantly important ecological functions and values with wide ranging benefits. Using natural conditions in designs that create maintenance free habitats that otherwise do not exist, can generate significant benefits. Good projects are environmentally compatible, great ones are beneficial. © 2011 ASCE. Source

Sharma R.,Ocean and Coastal Consultants Inc. | Baxter C.,University of Rhode Island | Jander M.,University of Rhode Island
Soils and Foundations | Year: 2011

Small strain shear modulus (G max) has been a parameter of choice used to assess the strength and deformation behavior of cemented and other sensitive soils. The influence of density, effective confining stress, stress anisotropy, and cement content on shear wave velocity (v s)/shear modulus has been studied extensively and published. There are, however, very few studies on the effects of cement/strength degradation during shear on the shear wave velocity/shear modulus, which may be important for reliable and accurate prediction of mechanical behavior of cemented sands. The objective of this study is to evaluate the effect of cement degradation on shear wave velocity/shear modulus by measuring continuously the shear wave velocity during shear. A laboratory testing program was performed using samples of silty sand artificially cemented with Ordinary Portland Cement (OPC). Shear wave velocity was measured continuously within the triaxial cell during the shear phase using torsional ring transducers. G max was calculated using the shear wave velocity and the corresponding density during shear. Results from this study suggest that G max reaches a peak value before σ 1 reaches a failure stress and this behavior is believed to be an indicator of bond breakage or destructuring. G max calculated at various stages during shear showed that the cement and modulus degradation can be represented by a simple index using G max. The results of this study suggest that there may be a unique relationship between small strain shear modulus and effective stresses at failure for dilative soils implying that in situ shear wave velocity measurements may be used to estimate effective stress strength parameters or as a precursor to failure in weakly cemented soils. Source

Jones B.N.,Ocean and Coastal Consultants Inc. | Decas K.,06 Co Op Wharf
Ports 2010: Building on the Past, Respecting the Future - Proceedings of the 12th Triannual International Conference | Year: 2010

Once the world's most famous whaling-era seaport, New Bedford now stands as the number one fishing port in the nation based on total value of catch. With a fleet of over 470 commercial fishing vessels and only 160 public berths, New Bedford is challenged with increasing demand for adequate space to safely accommodate the fleet. Overcrowding of commercial fishing vessels at the docks is common, and captains will often raft their vessels together up to six (or more) abreast at the piers during storms. Not only does overcrowding of the facilities pose obvious threats to the safety of vessels and crew; but also the associated pier structures, which were not designed to handle the berthing loads to which they are currently subjected. In 2007, the City explored engineering alternatives to relieve the congestion at its five public commercial docking facilities. The study analyzed the current berthing situation and provided a cost-effective engineering "action plan" that would provide additional berths for the fleet within the next three to five years. Establishing these alternatives was accomplished through both correspondence with members of the fishing community, city officials and industry stakeholders and the analysis of the current berthing situation. The proposed alternatives were a result of the evaluation of various layouts, including (1) the construction of new facilities, (2) establishment of mooring fields, (3) floating dock systems and (4) fixed pier expansion. The final recommendation from the study included the installation of a concrete floating dock extension to one of the existing piers, in conjunction with a partial de-authorization of an obsolete maneuvering area within the harbor's US Army Corps Federal Navigation Project to accomodate the expansion. © 2010 ASCE. Source

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