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By F. Keith Jacobson

To be involved in the construction of a deep dredged caisson for a major bridge pier is one of the most rewarding and professionally challenging experiences one can have in the bridge construction business. That experience was doubled in the construction of the two deep dredged caissons for the Highway 82 Bridge over the Mississippi River near Greenville, Mississippi. The challenges and the construction risks associated with constructing these two dredged caisson pier foundations highlight the construction engineering innovation associated with major bridge pier construction. The 1,378-foot Main Span of the Highway 82 Bridge makes it the longest cable stayed bridge span over the inland rivers of the United States. The main piers for this bridge are supported on two dredged caissons measuring 80-feet by 122-feet in plan, founding 200-feet and 170-feet below the river surface. The challenges of constructing these caisson structures, sinking them through 70-feet of water to the river bottom and then excavating and further sinking them to the founding grade without exceeding the design tolerances, were enormous. The construction engineering opportunities for innovation included major breakwater structures to create a friendly environment in 11 ft/sec currents, the first time use of Articulated Concrete Mattresses for river bottom scour control, unique air dome design to maximize the buoyancy of the caisson structure while floating, a caisson guide system to assure positive control and positioning of the caisson during the initial sinking phases, and a comprehensive sinking plan to assure maximum control and minimum risk. Many of the innovative solutions to the construction challenges on this bridge will be incorporated into future caisson construction projects on the lower Mississippi River.

Jan 1, 2013

By David K. Crapps

The drilled shaft load tests at Port Orange were part of a demonstration project sponsored by the Federal Highway Administration (FHWA) and the Florida Department of Transportation (FDOT). Three load tests were conducted. Test 1 was a conventional test with the test shaft loaded from the top. Test 2 included an Osterberg load cell at the tip and a conventional load test from the top. Test 3 used an Osterberg load cell at the tip of a production drilled shaft. All three test shafts were socketed into limerock and were carried to failure. This paper describes the test program and presents a summary of the test results. Figure 1 presents some photographs of the load test setups and Figure 2 shows the location of the drilled shaft load tests. SITE CONDITIONS The Port Orange Bridge is located on US A1A over the Intercoastal Waterway in Port Orange, Florida (south of Daytona Beach). The new bridge will provide four lanes of traffic with a 65 foot vertical clearance for Intercoastal Waterway traffic. The channel and flanking piers will be supported by 54" drilled shafts socketed into the rock. The bridge is being constructed in two phases. The southern half will be completed first, the old bridge removed and then the northern half will be constructed. The first phase is scheduled to be opened to traffic in October 1989. Each of the four piers near the channel will be supported by 12 drilled shafts with 6 shafts per pier being constructed in each phase.

Jan 1, 1989

By H. S. Radhakrishna

Foundations supporting power transmission and communications towers are subjected to both compression and uplift loads, often of a cyclic nature. Some novel foundations, combining the beneficial features of grouted and helix anchors with that of compression piles and grillages, were developed by Ontario Hydro during the construction of high voltage transmission lines in Ontario, Canada. In addition to meeting the load requirements, the foundations permit easy installation in swampy areas and also minimize impact on environmentally sensitive terrain. This paper describes the features of these composite foundations and outlines the performance criteria used for their design and installation on the basis of load test results.

Jan 1, 2010

By James D. Hussin

The Florida limestone is a relatively soft rock which presents many challenges to engineers when designing deep foundations. One alternative is micropiles which have grown significantly from their early days as very small diameter, light capacity elements. Also known as minipiles, pin piles, needle piles or root piles, micropiles offer an attractive deep foundation alternative for sites with tight access, low headroom, and where difficult subsurface conditions or obstructions necessitate a small diameter, high capacity deep foundation. The ability to confirm the competence of the limestone bearing formation by drilling in a rock socket has made micropiles a growing deep foundation selection in Florida.

Jan 1, 2003

By David C. Kraft

Atlas Systems, Inc. (ASI) resistance type piers were used to underpin a 100 year old historic structure at Fort Monroe, Virginia. This 3-story structure with basement was underpinned with 155 steel tubular push piers (4" OD) that were hydraulically installed to depths ranging between 90 and 110 ft. and to installing forces in excess of 60,000 lb. Project requirements included lowering the basement floor by 1-1/2 ft. and constructing new footings and adding stem walls to connect to the existing masonry walls. Additionally, the underpinning piers were temporary which required the development of a decoupling system to permit the transfer of the building loads from the underpinning piers to the new footings. The structural loads at the foundation level required a c. to c. pier spacing of 3.75 ft. in order to meet project requirements of a minimum Factor of Safety of 3.0 on the pier load capacity. Project requirements included a load test on the selected underpinning pier (ASI - AP2 4000.219) in order to establish installation depths for seating the piers to 60,000 lb. The project was successful in supporting the full load of the structure during the construction phase. Considerable savings in time and cost were achieved as well as avoiding any vibrations or noise during installation of the piers.

Jan 1, 2002

By K. K. S. Ho

In Hong Kong the design of excavated piles in weathered granite has conventionally been based on a rule-of-thumb which relates the allowable base bearing capacity to the SPT N value, with no allowance for skin friction. This rule-of-thumb has been shown to generally lead to conservative designs. To improve the overall understanding of load-transfer mechanism of excavated piles in weathered granite, instrumented pile load tests have been conducted. This paper summarises a selection of instrumented pile load test data in Hong Kong and the observations made of the results, which indicate that there was considerable scatter in the back-calculated skin friction values. However, the mobilized skin friction was shown to be significant which can lead to substantial savings in design.

Jan 1, 1996

By Matthew C. Pierson

Due to space limitations for transportation projects, many times sound walls must be constructed above mechanically stabilized earth (MSE) walls. These sound walls must resist lateral loads from wind or impact and must therefore be constructed on drilled shafts passing through the reinforced fill for the MSE Wall. Current design methods for the drilled shafts are believed to be overly conservative. Full scale lateral load testing of three foot diameter shafts contained within and solely supported by a 20 foot tall MSE block wall was conducted and the lateral capacity was evaluated. Shafts were tested individually and as a group. The data collected from full scale testing was then used to calibrate numerical models. This paper contains a discussion of how the facing type and stiffness affects the behavior of the numerical model as well as selected comparisons between the actual test data and selected model simulation results.

Jan 1, 2009

By Khamis Y. Haramy

Curing temperature, density, and moisture significantly affect the velocity measured in the crosshole sonic logging, the rate of strength gain, and the final strength of concrete in drilled shafts and, thereby, affect their structure capacities. Non-destructive field measurements can enhance the QA/QC program by measuring temperature, density, moisture, and sonic velocity of curing concrete during the construction and curing of drilled shafts. The curing environment can greatly affect the concrete strength, and requires close attention during construction. This article shares the experience with the NDE technology used in the QA/QC program in the drilled shaft construction. To understand the mechanism by which a drilled shaft cures under field conditions, two newly constructed drilled shafts were monitored for up to seven days, immediately following concrete placement using the following geophysical logging methods: a) temperature logging; b) crosshole sonic logging; c) gamma-gamma density logging; and d) neutron-moisture logging. One additional drilled shaft was also monitored to a shorter duration. Temperatures were monitored using the sensor in access tubes and/or thermocouples embedded at the center of a drilled shaft and near its reinforcing cage. For a small shaft under 1m diameter, curing temperatures appeared to peak at 41° ? 68° C at different depths at around 24-hour curing time and decreased to and stabilized at around 23° ? 35° C in 6 days. The shaft curing rate varied with depth, shaft diameter, surrounding geo-material types, and the depth of ground water. CSL logging was performed in one shaft from top to bottom from six access tubes and limited monitoring in another shaft. The velocity increased with curing time till 4 to 7 days, and, at a specific time, the velocity appeared to be inversely correlated to curing temperatures. The gamma-gamma density log (GDL) results from 5 different depths were obtained at a source-detector separation of 355 mm. The average density was found to increase with curing time, but decrease slightly in 3 to 5 days. At a given time the GDL density curves seemed to correlate with the neutron monitoring logging (NML) moisture curve. The NML moisture was monitored from 1st to 6th day after concrete placement. The moisture was highest when surrounded by bedrock, then clay, and sand due to different hydration rates.

Jan 1, 2007

By Clifford J. Wren

A geotechnical foundation solution was required to halt and prevent further structural distress suffered by a residential four storey apartment building in Hamilton, Scotland. Residents of the ten year old building started to notice cracking and signs of distress approximately one year after moving into the property. A detailed intrusive inspection of the structure revealed that the building was moving and had suffered significant settlement and structural distress at the shared party wall between it and an adjoining building. Roger Bullivant Limited (RBL) was appointed Principal Contractor to carry out an agreed remedial works contract which included a complete structural ?strip-out? of the ground floor, underpinning, contiguous bored pile retaining wall and reinstatement. The paper describes how a proprietary pile and needle beam underpinning system was used to prevent further differential movement and provide a new secure foundation for the residential building. The case study illustrates how a flexible problem solving approach can be applied to a difficult and sensitive geotechnical project.

Jan 1, 2008

By Mohammad T. Izadi

Piles are, often, used for transferring load from the super structure through soft consolidating strata onto relatively stiff uncompressible soils. Downward movement of the soft soil strata develops negative skin friction and dragload around the pile shaft, with time. Traditionally the induced dragload is considered in determining the pile bearing capacity. On the other hand, field measurements on instrumented piles show that negative skin friction is reduced by the magnitude of applied live load. A method for calculating the pile bearing capacity, driven through soft consolidating strata is presented. In this method, two allowable load-bearing capacities are calculated for each pile, live load plus dead load and dead load. The proposed method, substantially, increases the allowable load bearing capacity of piles compared to calculated values by the traditional methods.

Jan 1, 2001

By X. L. Chen

The diaphragm walling has been recently adopted in one of the largest excavation of deep foundation engineerings in Shanghai, China with dimension of 90m in length, 50m in width and 13m in depth to solve its stability problem. In this paper the field test for monitoring the stability of the diaphragm wall is discribed, in which the excess pore water pressure and the horizontal displacement of the clay layers were monitored during the period of the excavation. The data measured in the field test are efficient for the safety during construction.

Jan 1, 2010

By Frank Borda

Two recent projects were completed in Ontario, Canada for major hospital additions that involved excavation support of heritage masonry structures. Conventional continuous caisson wall schemes were replaced, with significant cost savings, by tied back shotcrete systems. Using a combination of conventional design and FLAC analysis, excavation support was designed to permit excavation in competent to weak soils that limited horizontal movements of the existing structures to between 3 and 8 mm. The use of vertical wall elements (micropiles) integral to the shotcrete wall to support both the vertical wall loads and the face of the excavation was deemed to significantly reduce lateral and vertical wall movements. FLAC analysis was used successfully to predict wall movements and optimize design. The shotcrete method proved to be flexible and adaptable to design changes during the project. This permitted convenient accommodation of changes to the building geometry after excavation support had commenced. In addition the method accommodated staged demolition and excavation support of portions of the existing structure at low cost, conveniently and without delays.

Jan 1, 2004

By Narong Thasnanipan

Performance of diameter 1.5 m toe-grouted bored pile founded at depth 44 m in sand-gravel formation of Chiang Mai City is presented in this paper. Toe grouting was applied by using tube-a-manchette method. Effectiveness of toe grouting was observed from the standard penetration tests conducted immediately below pile toe through grouting pipes at two stages, prior to grouting and three weeks after completion of grouting. Improvement of pile end resistance by toe-grouting is demonstrated with a series of back analyses carried out by load-transfer method employing hyperbolic transfer function. Construction experience of large diameter deep-seated bored piles in multi-layered subsoil and practical aspects of toe-grouting are also briefly discussed.

Jan 1, 2002

By James C. Scott

Compression and tension load testing were performed on bored concrete piles installed to depths of 18 to 34 meters below excavation levels for a large mixed-use development in Kuala Lumpur, Malaysia. The 900 mm diameter piles were installed in weathered graphitic schist bedrock. Load testing confirmed the side shear and end bearing capacities of the piles. The work formed part of the investigations for the 56,000 m2 site which includes a 79-story office tower, hotel tower, apartment tower, retail complex, and plaza area underlain by 4 to 6 basement levels. The paper provides the results of the site investigations, pile-load testing procedures, pile-load settlement behavior, and shaft load distribution.

Jan 1, 2007

By Tony Amis

There is very limited information relating to the potential impact of temperature cycles, outside the variation that occurs naturally, on the behaviour of foundation piles. Such thermal loading occurs when piles are used as heat exchange elements within a Ground Sourced Heat Pump system, in addition to carrying building loads to competent strata. An investigation has been undertaken where a conventional load test has been extended to include a period in which the load is maintained and temperature cycles applied. Instrumentation was installed in the test pile, an adjacent borehole, two of the anchor piles and the heat sink pile in order to be able to develop an understanding of the temperature variation and associated strain changes within and between the various elements. Conventional electronic strain and temperature gauges have been used in conjunction with optical fibre sensors which also measure strain and temperature changes. The results have confirmed the validity of the assumption made in the thermo-dynamic design of the system, the compatibility of the differing measurement systems and differing installation methods for the optical fibres, and initial assessment suggests that the load-settlement response of the pile is not adversely affected by the temperature cycles applied.

Jan 1, 2008

By Bill Paparis

The thirty year old wharf structures at the Port Authority of New York & New Jersey?s Port Elizabeth Marine Terminal are being modernized for the next generation of Post-Panamax container ships, which require deeper water and larger container cranes. The terminal operator is upgrading the wharf in order to remain competitive, now and into the future. The upgrade coincides with the Army Corps of Engineers? $733 million project to deepen the main shipping channel in New York Harbor. This paper focuses on the structural modifications to accommodate berth deepening and to support the heavier loads of the new cranes. An overview is provided of the design and actual construction, including typical problems encountered when combining new and existing structures. The wharf improvements included: ? Installation of a steel king pile/sheet pile cutoff wall along the face of the wharf to permit increasing the depth from ?12.2 m + 0.61 m to ?15.2 m + 0.61 m ( ?40 ft + 2 ft to ?50 ft + 2 ft) ? Removal of the existing crane rail support beams and installation of new piles and beams to support the increased crane loads ? Replacement of the existing timber fender system with a new system capable of resisting the berthing energy of a 152,000 MT displacement vessel, and having dedicated sections for berthing barges ? Replacing the existing overhead, landside crane electric feeder system with a waterside, cable reel trench system. The work included upgrading the transformer capacity at the terminal for increased crane power demands This paper provides a case history for port administrators, terminal operators, engineers, and shipping lines challenged with upgrading aging terminals.

Jan 1, 2013

By Ehab S. Shatnawi

It is common in practice to design laterally loaded rock-socketed drilled shafts using the p-y curve methods. However, the existing p-y curve criteria for rock were derived either semi-empirically or based on the assumption that the rock is an elastic isotropic continuum. The assumption of isotropy may be invalid for rocks with intrinsic anisotropy or for rocks with joints and bedding planes. Therefore, there is a need to develop a new p-y curve criterion to take into account the effects of rock anisotropy on the response of laterally loaded shafts. This paper presents a method for estimating the initial tangent Ki to the p-y curve for rock that can be characterized as transversely isotropic elastic continuum. Examples of transversely isotropic rock formation can be seen in most sedimentary rock where dominant bedding planes exist. The knowledge of the initial tangent to p-y curve is important, because it controls to a large extent the predicted deflection of laterally loaded drilled shaft in rock. The 3-D finite element parametric study results of a laterally loaded drilled shafts socketed in transversely isotropic continuum are employed to develop a series of design charts for estimating Ki as a function of transversely isotropic elastic constants.

Jan 1, 2007

By Andrew Cushing

This paper presents the design and construction of the foundation for a major high-rise real estate development on the west side of Manhattan. Arup was retained by Underpinning and Foundation Skanska to design a secant pile wall as excavation support for a proposed two-level basement of a new 23-story residential building located at 100 11th Avenue and West 19th Street. The secant pile wall will also act as the permanent basement retaining wall for the new building. The site is bounded on two sides by existing structures and is underlain by a thick deposit of very soft organic silt and clay. Therefore, the potential for ground movements and their impact on an adjacent structure bearing on shallow footings were of the utmost concern. This paper addresses the design and construction considerations associated with this secant wall, as well as installation details. Measured wall movements are also used to assess the validity of the pre-construction soil strength and stiffness design parameters.

Jan 1, 2008

By Ernest Naesgaard

Post-grouted micro-piles were used for the seismic upgrading of the Vancouver International Airport Domestic Terminal Building (DTB). The micro-piles provided vertical resistance to both uplift and compression loads to supplement the existing timber pile foundations ability to resist the earthquake induced forces, and to provide foundation support at locations where the installation of traditional driven piles was difficult. This paper describes the site conditions, design rationale, installation method and quality control testing procedures. Site and Subsurface Conditions Vancouver International Airport is located within the central portion of Sea Island, Richmond, British Columbia (Fig. 1). Sea Island is bordered by branches of the Fraser River on the northeast and south sides and the Strait of Georgia along the west side. The natural grade of the island is part of a large delta that has been built up over several thousand years. The general pattern of sediment deposition has followed the direction of the Fraser River flow from east to west, and has built up soft sediments of about 200 m thickness at Sea Island (Luternauer, et al. 1993, Mathews and Shepard 1962). The original grade in 1962 prior to the existing Airport Terminal Building development was at about geodetic elevation 1.1 m with a grass and topsoil cover.

Jan 1, 2004

By R. A. Fraser

Large diameter (1.0 to 2.5m) bored piles have been widely used to support buildings and elevated roadways in Hong Kong. Most of these piles are founded on a hard bearing stratum such as granitic or volcanic bedrock, in the newly reclaimed areas along the water-front, the bedrock stratum can be as deep as 70-80 metres below ground surface, and construction of bored piles to bedrock in this case is difficult and unjustified. Nevertheless, Building Ordinance Regulations in Hong Kong require piles to be founded on bedrock. To overcome this problem for elevated roadways, trial piles have been designed founded on dense, completely decomposed granite. A number of piles have been constructed and subsequently load-tested to allow the rate of mobilisation of skin friction to be measured. This paper outlines the design, construction and testing method, and comments on the test results from several trial piles. GEOLOCICAL CONDITIONS The geology of Hong Kong consists predominantly of acid volcanic rocks intruded by granite. The granite has been deeply weathered, and variations in sea level have produced a drowned coastline with sequences of alluvial, colluvial and marine deposits overlying the weathered bedrock. Reclamation has extended this coastline. Typical site conditions are described later in the paper.

Jan 1, 2010