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By Maurice Bottiau

When dealing with displacement auger piling, some general and fundamental issues have to be considered, irrespective of the system. More than with other pile types, the interplay between the soil conditions and the design and execution is of outstanding importance. This paper intends to address these issues and to summarize some critical matters in terms of design, execution and control such as : ? Importance of a reliable soil investigation ; ? Summary of the design as it is addressed in Europe for this category of piles ; ? Criteria for a good choice and control of the correct asset of the piles ; ? Importance of the concreting phase; ? Relation between the power and the engine characteristics of the drilling equipment with the final bearing capacity. For each of these issues detailed examples will be given as well as results of load tests and in-situ control during execution.

Jan 1, 2003

By John R. Davie

This paper describes the design and construction of two 5.6 MN capacity drilled piers installed to support the main loading elements of a large cantilevered gantry crane. The critical crane columns were located within and at the edge of an existing sheet-pile cofferdam, which had been filled with loose coal slag when it was originally constructed Due to the presence of the slag and the age and questionable condition of the sheet-piles, the drilled piers were installed to provide vertical and lateral supports for these columns. The lateral capacity of the piers was supplemented by two smaller drilled piers and two large spread footings that were linked by a system of grade beams.

Jan 1, 2006

By Frank Haehnig, Harald Krenn, Harm-Christoph Claassen

"The Wadi Dayqah Dam Water Supply Scheme represents one of the most important projects implemented by the Sultanate of Oman to ensure sustainability of water resources. The principal components of the project comprise two dams to impound the Wadi Dayqah, to store and supply drinking water to the local area and to Muscat, the capital city of the Sultanate.The Main Dam with a central spillway is a RCC Gravity Dam with a maximum height above foundations of 75m, crest length 400m; the Saddle Dam is a rockfill dam with central clay core, max height above foundations is 49m and crest length 360m. During construction of the Saddle Dam a key trench was excavated to 10m depth and filled with compacted clay connected to the central core of the embankment. Grouting utilizing cement grout was performed as a single line grout curtain prior to each filling operations. Both Dams are founded on soft Siltstone, Claystone, Sandstone and inter-bedded harder limestone.After construction of the Saddle Dam, once water was in the reservoir it became evident in early 2010 that some seepage was occurring apparently from the right abutment. This seepage became more marked when the reservoir first filled to discharge over the spillway in June 2010. In order to reduce the seepage, additional sealing works by drilling and grouting of a three row curtain up to 80 meter target depth were initiated to supplement the existing single row curtain. Part of this project for the sealing works has also been to drill additional investigation holes to provide more information and confirm extend of the additional sealing works and its limits.Züblin Ground Engineering was awarded the Additional Sealing Works Contract. Whilst Equipment was on Site, the opportunity was taken to carry out drilling and grouting on the Left Abutment of the Main Dam to reduce seepage through that abutment and to install additional standpipe piezometer for future monitoring of seepage patterns.Work on this Contract started on site in January 2013 and was substantially completed in January 2015.At the time of Tender Züblin Ground Engineering propose and Alternative Design in the form of a Secant PileCut-Off Wall, 85m long to a depth of 40m with additional drilling and grouting below the foot of the cut-off which was then included in the contractual scope."

Jan 1, 2016

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 Jason N. Scott

It is now possible using low-cost wireless technology and rugged hand-held devices to record data on site electronically and for that data to be instantly available to others. This could potentially eliminate many problems that traditionally lead to remedial work, such as poor communication and the late detection of non­conformances. However, determining how best to implement such a system and integrate it with the rest of the business process is far from simple. This paper looks at Stent's experience of these issues by way of a case study of the SHERPA system. This is a wireless site data collection system developed for use with rotary bored piling.

Jan 1, 2006

By Jinung Do, Sung-Ryul Kim, Juhyung Lee

"Model tests have been performed to investigate the vertical, horizontal and cone tip resistances of bucket pile embedded in sand by different installation methods; suction force by pump and jacking force by actuator. Micro-cone penetrometer is used to evaluate the variation of the effective stress inside and outside of the pile after installation. As a result of vertical pull-out test, the jacked pile shows 3 times larger resistance than the suction-installed pile. For horizontal pull-out test, the ultimate horizontal capacity and the slope of load-displacement curve on the suction-installed pile decreases by 22% and 40%, respectively, compared to the jacked pile. In cone penetration test, inside cone tip resistance of the suction-installed pile is about 40% smaller than the jacked pile, which indicates that the effective stress is reduced due to upward seepage of bucket pile in sand by suction force. Therefore, installation methods can affect the behavior of the bucket pile significantly.INTRODUCTIONA suction force occurred when bucket pile penetrates into sandy soils induces seepage flow into the bucket pile so downward seepage near the outside of bucket pile causes to increases the effective stress, while upward seepage inside the bucket pile decreases the effective stress (Mahn, 2005; Fig. 1). The effect of induced seepage causes to reduce the penetration resistance during installation. On the other hand, reduced effective stress can decrease the horizontal and vertical capacities of bucket pile by significant disturbance at the tip of the bucket pile due to the flow net. Due to the complexity and difficulty considering the effects of suction installation, many previous researchers generally have neglected the effect of suction installation in their experiments. Therefore in this study, the effects of suction installation on resistance of bucket pile is examined."

Jan 1, 2016

By Martina Balic

Dynamic properties of the drilled shaft foundations supporting Doremus Avenue Bridge were determined by forced vibration testing. The main objectives of the substructure testing at Doremus Avenue Bridge were: (1) site evaluation with respect to the dynamic soil properties, and, (2) shaft evaluation for the purpose of definition of their dynamic stiffness. The site characterization entailed crosshole testing for the purpose of evaluation of the shear modulus profile. The drilled shaft impedance evaluation was done through forced excitation using an electromagnetic shaker. The responses of the tested shaft, as well as the response of adjacent shafts, were measured for the purpose of evaluation of the shaft interaction. To gain a better insight into the shaft dynamics, one of the shafts was instrumented with five triaxial geophones distributed along the full length of the shaft. The scope and results of the site characterization, shaft impedance and shaft interaction evaluation are presented.

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

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 Roberto Nova

The selection of the Osterberg Cell (O-Cell) technology as the standard testing method for deep foundations of the Railways Po Viaduct in Northern Italy offered a relevant number of field measures on large bored pile behaviour in alluvial soils. The assessment of pile response during such ?non standard? testing procedure was performed through the comparison with standard top load tests on companion piles as well as by numerical models of the tests including a simplified pile-soil interaction scheme. As shown in this paper, the O-Cell technology allowed a careful assessment of the non-linear pile behaviour even at quite small loading levels as those required by a posteriori proof tests on production piles. Simple numerical models proved to be very effective in the simulation and the interpretation of pile behaviour during such unconventional testing procedure.

Jan 1, 2008

By Daniel Levacher

Pile load tests in site require extensive means of action and time. To get outstanding tests, the environmental test conditions must be perfectly known and acceptable. They concern the support installation, the loading, the access and instrumentation site conditions and the economical aspects. In particular cases as offshore areas, the load tests are not feasible. Moreover the variability of soil characteristics limits the interpretation results at the considered tested site. The use of centrifuge modellling offers an other way to study the loaded pile behaviours. Centrifuge tests lead to parametric approaches which constitute for geotechnical engineers an important data base tor recommendations and design codes. To accurately simulate pile behaviours by checking similitude laws linked to the studied problems, the installation of model-piles must be also representative of the in-situ piles. Driven piles account for a large part of the piles installed through the world, mainly for offshore or harbour constructions. So, to explore driven pile problems by centrifuge tests, miniature pile driving hammers must be developed and tested under macro-gravities. The paper describes two types of these ones in details. They are commonly used at the centrifuge centre of the Laboratoire Central des Ponts et Chaussées - (LCPC) - [Réf. 1] for different deep foundations researches. Performances and limitations are given for both miniature pile drivers and some results from their use are presented to illustrate the suitability of these apparatus.

Jan 1, 1996

By Serge Borel

An efficient design method is proposed for "piled-footing" and "piled-raft" foundation under lateral loads. It combines the methods used for the displacement design of shallow and deep foundations and takes into account the interactions between the piles and the cap or raft. This method has been applied to previous full-scale tests carried out in the United States. Two groups of six instrumented driven piles were laterally loaded several times: first with the concrete pile cap in direct contact with the soil, and then, after a thin layer of soil had been removed beneath the cap. The proposed method models well the real behavior of piled-raft foundations. It highlights the positive effect of the cap in contact with the soil, which reduces significantly the displacements and the maximum pile bending moments. These are divided by two for the analyzed case histories.

Jan 1, 2002

By Lawrence Piccagli

This past spring of 2006, BENCOR installed the concrete reinforced diaphragm walls for the COSMOPOLITAN RESORT & CASINO in Las Vegas, Nevada. The project highlights include the excavation of approx. 326.000 square feet of reinforced diaphragm slurry wall with a thickness of 30 inches and a depth of 100 feet using three reverse circulation trench cutters (hydromills) at the same time. The reinforcing steel cages were fabricated on the 8 acre jobsite and approximately 12,000 cubic yards of 4500 psi concrete was placed via tremie. The jobsite logistics of coordinating three trench cutters and three separate desanding/slurry plants as well as the reinforcing steel fabrication and concrete placement all under a very tight schedule was quite challenging. A second main exercise was the execution of a temporary excavation support. As the excavation depths extends between 66 and 72 feet, five to six rows of temporary tieback anchors were required. Anchor lengths range from 43 -83 feet at a maximum design load of 235 kips.

Jan 1, 2007

By Kyle M. Rollins

To improve our understanding of lateral resistance of pile groups, a series of lateral load tests were performed on a full-scale pile group using both static and dynamic loads. The pile group consisted of nine 0.6 m-diameter steel pipe piles driven into clay. During the static tests, the load was cycled fifteen times to evaluate the drop in lateral resistance that would occur due to repeated loading and the formation of a gap. The peak load typically decreased by about 15% from the initial cycle to the last cycle. The load carried by each pile was also measured and there was a significant drop in resistance for the piles in the trailing row relative to the leading row. The dynamic force was applied using the Statnamic loading system which produced a lateral force of 3500 kN (787 kips) in about 0.1 seconds. In two cases, dynamic loads were applied following application of 15 static load cycles. In these cases, the dynamic lateral resistance was about the same as the static resistance, likely due to gaps around the pile. In three other cases, the dynamic force was applied prior to the cyclic loading. In these cases, the dynamic resistance was 30 to 60% higher than the static resistance. Simplified analyses suggest that the difference in resistance could be attributed to damping produced by the soil surrounding the piles during the virgin loading.

Jan 1, 2002

By Denis Huber

The technical assessment of the final works on the "Stéphany Palace" project at Menton in France's Alpes-Maritimes region shows the importance of daily project monitoring based on the observation method recommended by the European standard Eurocode 7 which applies to Foundations and Geotechnical Engineering. Excavation operations to a depth of 10 m near the France-Italy railway track and adjacent buildings required precise observation of land deformations, regular piezometric monitoring as well as special design arrangements. Temporary active tie-rods were thus placed in phases in order to control deformations in the retaining structures resulting from excavation operations. The Menton region, terminating the Alpine arc of mountains, naturally required the consideration of seismic forces in phase in the lower floors of the building, directly linked to the buried walls. These calculations were carried out in accordance with the PS69/92 rules, calling for an increase in dynamic thrust under the effect of gravity field rotation.

Jan 1, 2002

By C. W. Sheng

In this paper conventional construction procedure is briefly described for the installation of stone columns in soft ground in China. A viewpoint concerning the mechanism of ground improvement by use of stone columns is presented for discussion. Based on the information obtained from field measurement and observation three important problems relating to the construction and design of stone columns are discussed. Finally, a case history is given to show that short stone columns floating within the weak soil layers may in some instance be used to improve the weak strata of great thickness.

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 Xuhui

Pile foundations are underground projects which are carried out under complicated site conditions, so it is difficult to summarize their characteristic patterns from the everchanging practical pile foundations. In combination with theories, the paper analyses the effects of sound reinforced concrete piles and various types of defective piles on the propagations of stress waves. Through testing on prototype pile models, by use of the transient dynamic method and comprehensive analysis in both time domain and frequency domain, their reflection characteristics and patterns are acquired. In addition, discussions are carried out in combination with some real projects. Our model tests include comparison of large scale pile models of 20X20cm in cross section, 5. 0m in length respectively in air, standard sand, and natural stratum; prototype model tests of digged piles of 0. 7-1. 2m in diameter, and 18m, 30m in length; prototype model tests of bored piles of 0. 6m, 0. 8m in diameter, 12-20m in length. Test results show that no matter in air or buried in medium, the intrinsic characteristics of sound piles and various types of defective piles are fixed. In their time domain waveforms and spectral diagrams, obvious regularity are shown, which proves that the relations between the pile natures and their dynamic responses are fixed, which provide basis for correct judgement of pile soundness and natures of defective piles.

Jan 1, 1991

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 Jesús E. Gómez

A recent bridge underpinning project provided a unique opportunity to obtain information on the load-deflection response of 260 hollow-core bar micropiles. All production micropiles were proof-tested to a maximum load of 125 percent of the design load. In addition, four verification tests were performed on sacrificial micropiles to at least two and a half times the design loads. This paper presents the results of the verification and proof tests performed for this project, and provides recommended values for design of hollow core bar micropiles in soils similar to those encountered. This work shows that hollow core bar micropiles provide a significant unit bond capacity in both granular and fine soils, which may be greater than that typically expected in pressure-grouted (Type B) micropiles. The hollow core bar system allows faster installation rates in the soil types encountered than other traditional micropile techniques, and can be installed with relatively simple quality control procedures.

Jan 1, 2007