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By D. K. ] [Gupta

The Foundations of the Shear keys and alround cut off for Power House -IV of the Western Yamuna Canal Hydroelectric Project at Bhudkalan, Haryana were to be laid at a depth of 26M below the N.S.L and 24.4M below ground water table. The foundation of the drainage sump was to be laid at still higher depth, Viz 29.OM below N.S.L. The Sub soil at the site consisted of Gravel with some amount of sand. The laying of the foundation at such a great depth, at a large depth below the ground water table and that too under such difficult sub-soil conditions encountered a large no of Geotechnical problems-viz excessive seepage, side slope sloughing and sand boiling during excavation. Under the circumstances at the site, the modified foundation construction procedure i.e a battery of M. S. Troughs was placed in flowing water conditions and concreted thereafter, resulting in a sizable cut in dewatering and reducing a significant amount of time and cost of construction affecting a saving of crores of rupees at the state exchequer. Sheet Piling was used to prevent side sloughing in the foundation pit.

Jan 1, 1996

By Fabio Santillan, Michael F. Zoccola

"Wolf Creek Dam and Lake Cum berland in Russell County Kentucky is operated by the United States Army Corps of Engineers (USAGE) Nashville District It is a combination 3,940 ft long (1,200 m) non-zoned clay embankment, a maximum of 215 ft (65.5 m) above top of rock and 1,796 ft long (547 m) concrete gravity section. Built in the 1940s, the limestone beneath the embankment is characterized by an extensive interconnected network of solution feature; varying from fist size to largecaves.In 2005, studies conducted by the Nashville Distrect concluded that a new seepage cut-off wall was needed as the existing cut-off wall, installed in the 1970s, did not go deep enough and did not extend laterally far enough to intercept all major karst features The dam was classified as a ""Dam Safety Action Classification I (DSAC 1) – Urgent and Compelling,"" the highest risk under USAGE risk category rankings. Also in 2005, under a USAGE risk screening program of its entire dam portfolio, Wolf Creek was classified as a Dam Safety Action Classification 1-Urgent and Compelling, which put it in the highest category. In 2007, an Independent External Peer Review from outside USAGE, concluded there was compelling evidence that a piping failure mode had re-initiated and was in an ""advanced continuation"" stage of development.Impounding approximately 6 million acre-ft (7.4x102m3) of water at flood storage, Lake Cumberland is the largest reservoir east of the Mississippi River and ninth largest in the United States. Catastrophic failure would result in widespread flooding, Ices of life and economic losses in billions of dollars.In 2008, the Nashville District partnered with a joint venture between finns Treviicos and Soletanche (ISM through a ""Best Value"" contract to construct a new seepage barrier wall. This acquisition method was used in lieu of a low bid contract due to complexity of the work and dam safety concerns. It took advantage of the experience and innovation of contractors by soliciting technical proposals that were evaluated independent of cost. Those proposals deemed technically qualified and responsive then underwent a trade-off analysis between ccst and technical approach and a selection was made of the one deemed to give the best combination."

Jan 1, 2013

By Wei Tu

A grade separation was required to allow uninterrupted traffic crossing for a busy rail spur and a county road. The grade separation was achieved by creating a 30-foot (9-meter) high embankment that incorporates two multiplate tunnels and allows the passage of a rail spur and an existing county road. The site is located in an abandoned meander channel in the floodplain of the Mississippi River, near Osceola, Arkansas, and is underlain by more than 40 feet (12 meters) of soft clay and interlayered clays, sands and silts. Without soil improvement, the post-construction settlement would exceed 3 feet, slowly crushing the proposed tunnel structure and cutting off the railroad. Preloading, combined with vertical drains, was used to accelerate the consolidation of the underlying soil layers and to reduce the post-construction settlement under working loads. Six settlement plates were installed to monitor the progress of consolidation under surcharge load. The Asaoka observational method and the hyperbolic fitting method were used to analyze the measured settlement data to predict the end of primary settlement. The in-situ consolidation coefficient, ch, was back calculated from the measured settlement data. The stress release caused by the removal of the preloading surcharge load and the tunnel installation was determined using a Plaxis 3-D finite element model. The measured and predicted settlement using Hansbo's analytical solution demonstrated reasonable agreement. Early removal of the surcharge and construction of the tunnel prior to reaching the end of primary settlement was accomplished by analyzing the post-excavation stress reduction achieved via tunnel construction.

Jan 1, 2009

By Alan G. MacKinnon

The current piling practices in the U. S. have, to a great degree, been influenced by our founding fathers. When our constitution was written by the delegates from the original thirteen colonies, it was a document of compromise. Generally, the individual states retained their sovereign power over those duties that they had historically performed. The concept of States Rights has been tested throughout our history and has been preserved as of today. An example of the extent of this protection is occurring in the State of Ohio where I currently live. Each of the 50 states receives funds for highway construction from the federal government, approximately in proportion to its population. Congress, when it allocates the funds, quite often attaches amendments to the funding bill to exercise their authority. The major amendment prior to the most recent increase in the speed limit to 65 mph from 55 mph was to increase the legal drinking age to 21 from 18 years old. Embodied within the bill was the provision that the Federal government deduct a percentage from the allocation of any state that did not revise its legal drinking age law from 18 to 21. In the State of Ohio, this change in the law was put to a vote of the people and it was defeated. The federal government now is deducting funds

Jan 1, 1987

By Roderic A. Ellman

The new Woodrow Wilson Bridge (WWB) will replace the existing bridge over the Potomac River to connect Alexandria, Virginia to Prince Georges County, Maryland. The new WWB will extend approximately 1.1 miles across the river, with a 367-ft long bascule span in the main river channel where the water depth is about 36 ft. The subsurface soil profile consists of up to 50 ft of a soft organic silty clay layer that is very vulnerable to scour, underlain by a deep deposit of hard sandy clay. Foundation construction in the Potomac River required the use of cofferdams to allow structural concrete work to be performed in the dry. This paper will the present the types of cofferdams used to construct the foundations for the WWB replacement project. The bridge is primarily comprised of fixed spans in relatively shallow water and a bascule span over a navigation channel in relatively deep water. Foundation construction included the installation of 48" to 72" open end steel pipe piles and cast-in-place concrete pile caps. To achieve the desired bridge appearance, pile caps were required to extend below the water surface and below the existing river bottom in shallow water locations. Conventional steel sheet pile cofferdams with tremie concrete seal were used to construct fixed span, shallow water piers. Selection of deep water bascule span foundation cofferdams was governed by several factors including contraction scour, environmental considerations and cost. Potomac River cofferdams, i.e., relatively shallow depth cofferdams that are supported by the foundation piling were selected. This cofferdam system provided a shallow profile which minimized contraction scour and the amount of filling in the river. Design issues include load selection and cofferdam stability in very soft alluvial soils. Construction issues include erection sequence, tremie concrete mix design and placement procedures.

Jan 1, 2005

By Z. Q. Bian

The wireline sampling originates from core drilling in rocks. The authors combined the wireline sampling technique with conventional undisturbed soil samplers, including Osterberg sampler, Denison sampler and double tube barrel, and then developed the wireline samplers of WPS, WSS and WSR models. These samplers are able to sample various soils. They reserve all the advantages of the original samplers, and moreover, they are noted with quick hoisting and lowering by wire rope. Therefore, it becomes an efficient new technique of sampling undisturbed soil from deep foundation.

Jan 1, 2010

By W. Morgan NeSmith

Drilled displacement (DD) piles often develop significantly larger unit shaft resistance values than other drilled or augered pile systems in coarse grained materials. Minimal vibration and limited spoil development are also associated with DD pile installation and these factors are frequently additional financial and/or environmental benefits of the system. The application of DD piles in North America dates to the mid-1990s and their use in the Midwestern United States has been significant, particularly in the past 10 years. The authors have collected an extensive database of DD pile performance in the United States. The alluvial and glacial deposits of the Midwestern U.S. provide conditions where drilled displacement piles perform very efficiently when compared to coastal and residual geologies. This paper presents a summary of the authors? experience regarding installation and performance of DD piles in the Midwestern U.S. Information presented includes summary presentations of DD performance across a range of site conditions as well as a discussion of the relationship of DD performance and installation effort in the Midwest as compared to other geologic settings in the U.S.

Jan 1, 2009

By H. Mori

Construction of cast-in-place piles with enlarged bases has become popular in the cities in Japan facing to the sea coast, where the subground soil is soft alluvium deposited to depths often exceeding 30 m. The groundwater table is a few meters below the ground surface. Skin friction of piles may become negative due to ground subsidence or reduced due to liquefaction of loose sand during an earthquake. To support highrise buildings, depths of bearing strata to which piles are embedded often exceed 50 m. Due to such geotechnical conditions, methods and equipment to build cast-in-place concrete piles mainly built by the reverse circulation method have been developed since the 1970s. In the first half of this paper, the authors review the cur-rent practise of building cast-in-place piles with enlarged bases. Then they introduce the TFP system developed in recent years, and discuss about the procedures to control and monitor enlarging of bases.

Jan 1, 1989

By D. E. Sherwood

Twelve toe grouted, and eleven ungrouted piles, founded in very dense sands have been analysed to establish how toe grouting enhances pile performance. It is shown that pile stiffness is greatly increased, and that pile bases work effectively. This is in contrast to ungrouted piles, where some milli­meters of base movement may be required before the base is mobilised. Grouting appears to recover most of the disturbance caused during construc­tion, but in general does not enhance the ultimate bearing capacity of undisturbed ground.

Jan 1, 1989

By C. Michael Morgano

Static tests are costly and time consuming, so they are not always the best answer [ ]

Jan 1, 2005

By Ryan Law

Ground energy systems are being installed in increasing numbers in the United Kingdom. This is particularly true in London where planning regulations require larger scale developments to provide at least 10% of their entire energy demands from renewable sources. A common approach has been to use the groundwater from the Chalk aquifer as a source of energy. This paper explains the potential long and short term sustainability problems with groundwater based systems sited in central London (or any other urbanized area). It also outlines an approach to site testing and numerical modelling to ensure that the system functions well throughout its lifetime. This approach is then applied to a project located in central London.

Jan 1, 2008

By B. Francis

Literature provides only limited information regarding the behaviour of laterally loaded piles socketed into weak rock masses. A laboratory program, comprising a number of tests of scaled models of the pile/rock mass system has been conducted. A synthetic rock, known as Johnstone was used to simulate a naturally weathered and fractured siltstone. The load-deflection behaviour of the test piles was measured, and strain gauges were fixed to the model piles to assess the bending moments. The laboratory results are compared with the results from several theoretical models, some of which are in the form of commercial software packages. This study highlights the inadequacy of existing methods to adequately model the influence of rock joint orientation in geotechnical design. Additionally, numerical modelling of the pile/rock mass system was carried out using the discrete element program UDEC. The importance in modelling the system using discontinuum mechanics is highlighted, particularly to capture the anisotropy of the rock mass.

Jan 1, 2004