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By Hayel M. El-Naggar, Sherif A. Akl

Although grouted piles have been used for several decades since the idea was proposed in the 1970s, their design is mostly based on experience and unpublished proprietary methods. There is little research on grouting drilled shaft tips and even less on grouting shaft sides. This paper presents the analysis of 4 instrumented pile loads tests on base and shaft grouted piles from different sites in Egypt; with emphasis on one of the tests, to demonstrate the analysis process. The data from the tests are analyzed to model the development of unit side friction (USF) with relative displacement. A numerical model using the finite element software PLAXIS is used to investigate the effect of grouting on the surrounding soil stress state. The paper combines the observations from full scale pile load tests and results from the numerical model to suggest an idealized behavior of side friction development with relative displacement of the grouted part of the shaft. The suggested model considers an envelope of Unit Side Friction (USF) with relative displacement, initially dominated by the grout resistance then at higher relative displacements, the friction with radially pressured soil takes over. The grout provides very high USF values up to a relative displacement of 2mm. Then, the USF drops to a typical pile soil side friction behavior; however, this friction is affected by the contact stress between pile and soil, which significantly increases due to compaction grouting. INTRODUCTION Base and shaft pile grouting has been significantly developing in recent years to accommodate the unfavorable conditions in major projects such as the high loads in high rise building and founding on problematic soil formations. Grouting aims to decrease settlements and increase the capacity of the pile under axial load. The technique is first introduced by Kraft (1974) but gained popularity in the 1980s. Typically there are two types of grouting; compaction, and permeation. Compaction grouting is more common in pile foundations practice, and many researchers have provided case histories of pile load tests on base grouted piles and base and shaft grouted piles (Gouvenot and Gabaix,1975; Stocker, 1983; Ghazali et al., 1988; Fleming, 1993; Kusakabe et al., 1994; Robson and Wahby,1994; Joer and Randolph, 1998; Hamza and Leoni, 1998; Mullins et al. 2000; Littlechild et al., 2000; Suckling and Eager, 2001; Dapp and Mullins, 2002; Ho, 2003; Fu and Zhou, 2003; Brettmann and NeSmith, 2005; Ruiz, 2005; Mullins, 2006; Dapp and Brown, 2010; Beadman et al., 2012; Nguyen et al., 2013; Miller et al., 2013; Sinnreich and Simpson, 2015; Hui and Lin, 2015). Compaction grouting is meant to densify the soil around the pile and below the base rather than permeate this soil and increase its cohesion. Research showed that grouting increases the capacity of the piles by a factor of 2~5. The variation in capacity increase depends on pile type, grouting process, and especially grouting pressure. Although there are many case histories of pile load tests on grouted piles but there is no well-defined agreed-upon method to predict grouted pile capacity as typically done in ungrouted piles. Few lab experiments discussed the shaft grouting effects on the soil especially the compaction grouting. The experiments concluded that the compaction grouting forms a homogeneous layer between the pile and the soil, and a residual effective stress is achieved simultaneously with a significant densification of the soil around the pile with noticeable decreasing in void ratio. (Fattahpour et al., 2015; Wang et al., 2015). Recently, studies used numerical analysis to investigate the behavior of the grouted piles and the changes in the surrounding soil (Chiang et al., 2013). That study presents a simulation of the base pressure grouting with a simple FE model and predicts the reduction of the pile settlement by 10 to 20%. Another numerical study using a complex model conducted by Zhou et al. (2017), pr

Jan 1, 2018

By Michel Bustamante

The original Cistercian Lure abbey situated in eastern France and built in the second half of the 16th century, has become nowadays an administrative building. Because it has been founded on poor ground conditions and inadequate foundation scheme, the abbey has suffered severe structural distortion. In 1992 an inspection revealed new extensive damages which led to a general refection together with a foundation underpinning. Micropiling was the selected method. Movements recorded over a period of 6 years after underpinning completion are presented.

Jan 1, 2002

By Eric S. White, Thomas J. Sabourin, Khuram R. Mohib

"This paper presents the challenges associated with the design and construction of a steel sheet pile cofferdam supported with one level of grouted anchors in clean to silty sand with gravel. The initial assessment of the subsurface conditions indicated loose to medium dense soil with intermittent dense to very dense layers with no occurrence of cobbles and boulders. Sheet piles were proposed to be installed to a depth of 24 m below the ground surface to limit dewatering requirements for the cofferdam. During sheet pile installation, refusal of piles occurred at multiple locations forming passages for increased flow into the cofferdam. Modifications were made in the design of the dewatering system as a result of the increased flow. Finite element modeling was used to select the necessary modifications to the dewatering system within the cofferdam. Wells were installed based on the findings of the numerical model. Model simulations showed good comparison with monitoring of the field installed dewatering system.INTRODUCTIONIt is necessary to consider the impact of the ground water, subsurface stratigraphy, strength, and drainage behavior of the soil for the design and construction of cofferdams. This paper presents a case history of the construction of a cofferdam in Northern Ontario, Canada. The project consists of the construction of a powerhouse, intake, and tailrace which will generate around 28 MW of renewable clean energy by diverting water from New Post Creek through a power house and discharge into the Abitibi River. The focus of this paper is the dewatering and excavation support required to permit construction of the powerhouse. The layout of the cofferdam is shown in Fig. 1. The cofferdam for the powerhouse is rectangular in shape with sheet piles on all four sides intended to be driven to the design toe El. 101 m. The east and west walls have a length of 46.3 m. North and south sides are 47.6 m long; and in addition, two cantilever sheet pile walls bound the tailrace on the west side and two cantilever walls were installed on the east for construction of the penstock inlet. The ground surface in the powerhouse cofferdam area, before commencement of sheet pile driving, was brought to El. 125; the ground then slopes up to the East, toward New Post Creek, and the site is bounded on the West by the Abitibi River. 186 pairs of sheet piles were used to create the cofferdam and cantilever walls. The deepest excavation is to elevation 114.4 m. Within the west half of the cofferdam footprint, the base of excavation slopes upward at 3H: 1V to facilitate the tailrace discharge into Abitibi River.SOIL STRATIGRAPHYThe cofferdam design was based on the geotechnical investigation conducted by AECOM (2014) which included two relevant boreholes near the powerhouse footprint. The ground elevation at the time of investigation varied between 131 to 129 m. The material observed to the full depth of investigation was comprised generally of coarse to fine sand and gravelly sand or a sand matrix with gravelly inclusions. Some intermittent layers of clay and silt intrusions were also observed. Generally the soils grade finer away from the river. SPT N60 values were recorded in two borings during the field investigation with values reported from 3 to 92. The in-situ conditions ranged from compact to dense with some loose and some very dense zones. Figure 2 shows the variation in SPT N60 values with elevation."

Jan 1, 2017

By Gordon Demetrick

3900 Yonge St. was not a typical site on which to build a condominium apartment. A steep hill covered the majority of the site. In order to use as much of this site as possible, the rear of the building was to have nine stores cut into the face of the hill. A permanent shoring system was required as the building structure was not designed to provide sufficient stabilizing elements to support the total earth pressure. The total excavation depth required was 36 m (120'-0") with the upper 12 m (40'-0") to be backsloped. The vertical face of soil to be supported was 24 m (80'-0'). The shoring system originally designed by the Structural Engineer was to support this face by installing soldier piles and inclined earth anchors. During bid preparation it became evident to us that the system as designed would be difficult and expensive to install due to wet soil conditions. An innovative design was required to overcome these problems. Anchor Shoring hired John Stephenson Consultants Ltd. to aid them in accomplishing this goal. After extensive investigation together with The Trow Group, a unique design was proposed which provided a practical solution to the shoring problem.

Jan 1, 1987

By Anuj K. Singh, Shuvranshu Rout, Manos De

"Foundation for tracks of coke transfer car and dust extraction pipe was designed as series of isolated foundations spaced at 11.0m along length of coke oven battery resting on soil at depth of 2.5m. In one region the foundations are close to adjacent 12m deep underground junction house. Five foundations in this zone were constructed on backfilled soil without proper compaction instead of engineering soil fill or concrete fill. The foundations settled under loads and the supported frame structure tilted after equipment erection and during trials endangering the safety of the structure and equipment operation. The distorted structure had to be rectified in-situ by arresting settlement. In order to stabilize the foundation and supported structure the supporting soil had to be strengthened in situ without any dismantling, reconstruction and adverse effect to equipment operation. This paper presents the case study on the evaluation of defects for the foundation failure and analysis of the problem, proposed rectification of the situation by appropriate soil stabilization scheme, monitoring of the stabilization operations and verification of effectiveness of the rectification work by measurement of settlements. The implemented solution has ensured safety of the structure and equipment without any adverse impact on normal operation.INTRODUCTION AND BACKGROUNDNew Coke Oven Battery was being installed for an integrated Steel Plant. The hot coke from oven is pushed out after completion of coking process through a coke transfer car onto a hot coke receiving car. The coke transfer car runs on rail track parallel to the line of ovens forming the coke oven battery. One rail is supported on the structure of the operating platform of the battery and the second rail rests on independent structure of track beams. A large diameter pipe for extraction of the dust emitted during coke pushing operation is also supported on the same structure that supports the track beams. The entire structure rests on columns spaced at approximately 11.0m along the length of the battery. The columns transfer load to ground through individual foundations resting on competent subsoil strata.Two sets of foundations for the rail track beam support and dust extraction pipe support are adjacent to deep underground junction house of coke carrying conveyor. The depth of the pit for the junction house is 12m. The layout and arrangement of the foundations in this region around the junction house (JH-1) is shown in the “Figs. 1a, 1b”."

Jan 1, 2017

By W. Lum

In the U.S., flexible metal pipe culverts are designed by ring compression theory because the pipes are capable of deflecting and deriving side support from surrounding ground. For economy, tunnel liners are often designed as flexible structures that depend on the lateral pressure of the surrounding ground to maintain stability. In this paper, simple formulas are presented to determine the maximum deflection a concrete tunnel liner may assume and the ring compressive strength of the deflected liner. A tunnel can then be constructed to work within these limits. Similar techniques may be used to design concrete pipes.

Jan 1, 2010

By Vidyaranya Bandi, Madhav Madhira, Kota Vijay Kiran

"Using hyperbolic relationships for the non-linear responses of shaft and base resistances, a method is proposed for estimating initial shaft and base stiffnesses and ultimate shaft and base resistances of a pile from pile load test results. An iterative procedure is used to arrive at the values of shaft-soil and base stiffnesses and the ultimate shaft and base resistances. The method is applied to load - displacement data available from pile load test results to illustrate its efficacy.INTRODUCTIONA pile foundation is the most effective and economical solution in transferring large vertical loads to deeper depths. As the pile is subjected to axial load, the soil mass surrounding the pile is vital in providing vertical support for the pile. The nature of pile–soil interaction is three dimensional and to complicate the problem further, response of soil is nonlinear. Finding a closed form solution to such problem is extremely difficult. Several methods were developed to study and predict the response of the composite pile–soil system. Faruque and Desai (1982) implemented both numerical and geometric non-linearities in their three dimensional finite element model. Rajashree and Sitharam (2001) developed a nonlinear finite element model of batter piles under lateral loading using a hyperbolic relation for static load condition and modified hyperbolic relation, including degradation and gap for cyclic load condition.The ultimate capacity of the pile is estimated considering the strengths and unit weights of soil layers with depth, overburden pressure and other relevant parameters. The estimated capacities always need to be validated by conducting initial maintained load test. The estimated capacity may differ with the actual at site since the values of strength, stiffness, interface resistance between pile and soil, lateral earth pressure coefficient with depth and soil stratification, etc., differ from the design parameters considered for estimating the ultimate capacity of pile. The estimation of axial capacity of piles involves considerable uncertainties in selection of appropriate design parameters and the design rules are not always consistent with the installation procedures/processes involved."

Jan 1, 2017

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 W. Sondermann

"AbstractThe construction of a distribution centre of minerals for a global mining and resources cooperation demanded the control of deformations and displacement of the stack reclaimer facilities on very inhomogeneous subsoil conditions. The variation of quality from soft clay with CPT values below 1 MPa up to rock formations were the challenge in design and execution of all the foundation works.The advanced design considerations were resulting in a barrier wall system to limit the deformations of the up to 40 m deep bored pile of the stacker-reclaimers, whereas the layout of the barrier wall and the stiffness of the elements had a major impact on the residual lateral forces to be absorbed by the bearing structure.IntroductionA large international raw material distribution organisation is currently building an iron ore and pellet distribution centre on the north-western coast of Malaysia. The distribution centre will handle around 90 MTPA (million tons per annum) of iron ore and includes accompanying plants for loading and unloading iron ore and pellets, pelletizing plants as well as corresponding storage space for these raw materials. The total storage space extends about 800m north to south respectively 1400m east to west and is about 200m from the coastline. The project area is located in a wide valley basin, bounded by a range of hills to the north. The existence of soil with low bearing capability in the area designated for the plant meant that measurements for ground improvement were required in the storage areas, in order to combine the needs of iron ore and pellet storage areas with requirements of the loading facilities as the overall project demand.Project LayoutThe iron ore distribution centre and the pelletizing facility both consist of an import/export jetty, material handling facilities, pellet plant and the associated infrastructure. This publication describes the execution of ground improvement and foundation works for the loading and storage system, which consists of five rows of stockpiles and four intermediate rows of stacker-reclaimers. The total area of these systems comprises 278,881 m2 (Fig. 1)."

Jan 1, 2014

By Frederick C. Rhyner

Drilled shafts have become an economical foundation choice for bridges in the northeast United States, especially when they can be constructed over water without the use of cofferdams. For the Boscawen-Canterbury Bridge over the Merrimack River in New Hampshire, an unusual design was used to avoid the use of cofferdams and avoid the need for pier caps at the waterline. This design used a pair of integral drilled shaft ? columns to form a bent type of substructure for support. Drilled shafts were 8-foot diameter, about 90 feet deep, with 16-foot long rock sockets. These are integrally constructed with 6-foot diameter reinforced concrete columns extending 37 feet from the waterline to the superstructure. Design load cases focused on lateral loads from ice flows, stream flows, wind and seismic events. Alternative analyses using different methods were made to check the design results. This paper discusses the subsurface conditions, design of the drilled shafts and columns, rebar and joint detailing issues, and construction of the drilled shafts.

Jan 1, 2004

By Eric S. Lindquist

High groundwater levels combined with variable soil and rock profiles present challenges to the design and construction of deep excavation support systems. Increasingly, secant piling techniques are the preferred technical solution for shoring in these cases. Recent developments in drilling equipment, tooling and procedures allow cost-effective construction of deep, overlapped pile systems to tight tolerances in extremely difficult ground conditions. This paper summarizes critical design considerations for secant pile shoring systems, detailing recent advances in installation procedures and verification techniques that allow secant piles to be used for an expanding range of project conditions. Technically- and commercially-viable secant pile shoring designs require that stringent drilling tolerances be achieved in order to successfully provide combined structural support and groundwater cutoff systems, particularly for unreinforced circular secant pile shafts acting in ring compression. Modern drill rigs and tooling can advance fully cased shafts in geotechnical conditions which range from cohesionless soils below the groundwater table to hard rock, within a single drillhole. Down-hole instrumentation provides verification that tolerance requirements are met and allow secant pile shoring to be used at sites previously considered unacceptably risky. In California, secant pile shoring systems are being used for excavation depths of over 100 ft (30 m) on projects with challenging site conditions. Two case studies are presented detailing severe geotechnical conditions and excavation depths which represent the regional state of practice in secant piled excavation support. These projects provide real world examples of the design, construction and construction verification techniques that permit secant pile shoring to be used in more demanding geotechnical conditions and to greater depths than ever before.

Jan 1, 2011

By Shaw-Shong Liew

This paper presents the processes of investigation, analysis, design, construction and monitoring of soil nail stabilisation work to facilitate a 14.5 m deep excavation at an uncontrolled fill ground. An extensive instrumentation programme had been implemented to monitor the performance of the stabilisation solution, to provide validation for the designed nail resistance and groundwater variation. From the monitoring results, it was proved that the soil nail stabilisation technique is effective for loose saturated fill provided that substantial care is taken during implementation. Construction difficulties, solutions to overcome the problems and lessons learned will be discussed in the paper.

Jan 1, 2006

By Luca de Sanctis

The analysis of piled raft foundations in layered soils may be performed by 3D finite elements or by approximate procedures. Among the latter, the code NAPRA (Russo, 1998) is based on the method of the interaction factors and accounts for soil layering by the so called Steinbrenner approximation. A comparison between the results of 3D FEM and NAPRA for some reference layered soil profiles shows that the approximation is fully acceptable for engineering purposes, provided the stiffness of the single pile is properly selected. The interest of the conclusion lies in the fact that the amount of work needed to model a practical problem by NAPRA is but a fraction of that needed by FEM modelling.

Jan 1, 2002

By Anthony L. Reynolds, Clifford J. Wren

"The adoption of a significant pile testing regime, the use of Eurocode 7 as the design standard, the development of lean construction techniques, and lateral thinking in overcoming some considerable construction challenges allowed Stent Foundations to construct the foundations for the new Wembley Stadium, London, on time and within budget. In addition to the piling works for the main stadium, and after significant design development, a large number of extra piles were required to raise the new iconic roof Arch to its final position some 133 metres above the ground. A 1,400m long contiguous bored pile wall was also constructed to allow for excavation and formation of the new pitch. INTRODUCTIONHjstorjcal lntrodyctionWembley Stadium is the 'home of English football'. As long ago as the 1880's, Wembley Park leisure grounds had football pitches and running tracks.In 1918 the British Government began planning a British Empire Exhibition with a stadium as its centrepiece. The Exhibition area covered 219 acres and the area on which a former abandoned tower called Watkins Folly had stood was chosen as the site for the new stadium (http://www.wembleystadium.com).The Empire Stadium, as it was originally known, was designed by architects Sir John Simpson and Maxwell Ayerton and the engineer Sir Owen Williams. It took just 300 days to complete at a cost of £750,000 ($1.4m), and was built using 25,000 tons of ferro concrete, 1,000 tons of steel, and over half a million rivets.The Empire Exhibition was a remarkable event, containing fountains, lakes, gardens, and many pavilions, each representing the architectural style of the countries exhibiting. It was opened on 23rd April 1924 and the final attendance was over 27 million, with 4.5 million admissions to the Empire Stadium alone."

Jan 1, 2005

By Jogeshwar P. Singh, Aser I. Abbas, Mohamed Ashour

The presented methodology predicts the pile head response (i.e. pile head load - displacement curve) and develops the load transfer (t-z) curve of piles in sandy soils under tension forces based on soil/pile properties and soil-pile interaction. The proposed approach improves the prediction of the t-z curve in sandy soils compared to current practice. The method employs a nonlinear soil constitutive model to calculate the mobilized shear stress/strain in soil at the soil-pile interface induced by pile upward displacement. The approach accounts for the influence of the pile slenderness ratio on the predicted t-z curve and is validated through comparisons with measured pile head response and t-z curves from full-scale pile load tests. INTRODUCTION Piles may be subjected to axial uplift forces due to either static loading or cyclic loading. The majority of methods are only concerned with the pile ultimate tensile capacity. However, the mobilized pile stiffness (i.e., pile-head load-displacement relationship) is essential to determine the interaction between the foundation and the superstructure and consequently the performance of the whole structure. Methods that assess the pile ultimate tensile capacity usually assume the failure surface at the soil-pile interface and estimate the local side shear resistance using a lateral earth pressure approach. The Naval Facilities Engineering Command (NAVFAC 1986) and the US Army Corps of Engineers (USACE 1991) employed Eq. 1 to assess the ultimate shear stress (τ) developed at the soil-pile interface.

Jan 1, 2018

By Dale E. Berner

A new navigation dam at Olmsted on the Ohio River will be built "in-the-wet" using a lift-in construction method by the Washington Group/Alberici Joint Venture for the U.S. Army Corps of Engineers, Louisville District. Up to 4,000-ton precast concrete dam shell segments will be prefabricated on the Illinois riverbank and lowered into the river on a marine skidway and cradle. A 4,500-ton capacity catamaran crane barge will lift the precast concrete shells and lifting frames from the cradle, and transport them partially submerged to a piled foundation pre-installed underwater. Tremie concrete will be used to compositely connect the shells, piles and sheet pile cut-off walls. This paper focuses on the pipe-pile foundations for this half-mile long navigation dam, and for the temporary precast yard and marine skidway. The dam foundations are designed to resist large ground motions from the New Madrid Fault Zone, and selected production piles are designed to serve as landing piles to support the shells during the construction process. Specific foundation issues addressed in the paper include: pile load tests; production field testing requirements; controlled fixity 24-inch diameter pipe-pile design including seismic considerations; cut-off wall design; sheet pile cellular fixed weir design; isolation jOint design; and temporary works foundation designs for both the precast yard and the marine skidway, including testing of 42-in diameter pipe piles.

May 11, 2007

By Leong, William. Chong, Kam Weng

Deep Vibro Techniques namely Vibro Compaction (VC) and Vibro Replacement (VR) are widely used in ground improvement to densify sands and strengthen cohesive soils. This paper describes the application of these techniques for the construction of 20 Ha Iron Ore Stockpile Yard with the maximum stockpile height of 14 m in Quang Ngai, Vietnam. The challenges of this project are to limit the stockpile allowable settlement and the surrounding pile’s lateral movement. The soil condition can be summarized as 12m – 18m thick of loose to medium dense SAND with qc around 5-18MPa and followed by 2.0 – 6.0 m thick soft clay with qc around 0.4 – 0.8MPa. Localized very dense sand layer was found. VR using stone columns were installed in soft clay layer while VC was adopted to densify sand layer. Additional shallow stone columns were built in sand strata to minimize pile top lateral movement. The post construction performance was verified by a large 6 m by 12 m plate load test (PLT). The predicted PLT deformation using Priebe’s improved properties for the VR will be presented and compared with the measured plate load test results.

Nov 1, 2022

By M. England

Test equipment has been developed to record automatically both the displacement of the pile head and the load applied during a conventional maintained load pile test. Some systems also have, in addition, been fitted with the facility for maintaining the applied load, as set by the operator, at very constant levels. The advantages are both commercial and technical, but a well trained operator has to be in attendance to control the test. Since typical test specifications in the UK require more than 19 hours to complete, it became inevitable that at least one equipment operator remained on site to expedite the test for its duration. Although electronic measurement and data logging of load tests may be more safe than previous direct observation of dial gauges. A single person remaining on a construction site alone is not to be recommended, even if they are just supervising the test. Further development of the testing system produced equipment which will perform the entire test specification as required without operator intervention. To achieve this, full automation is employed. The patented method particularly addresses the safety requirements and by using additional sensors, detects any uncharacteristic behaviour of the pile under test or of the reaction system and the equipment takes appropriate action in a controlled and safe manner. The quality of test data returned from these automated systems is a key element when analysing pile behaviour with models such as CEMSOLVE? and TIMESETTM. These analysis methods often indicate ground disturbance resulting from installation technique and have allowed pile design to be optimised using actual field data rather than theoretical considerations alone. An additional feature is remote access, this allows the data recorded to be transferred and the progress of the test to be viewed from practically any location. This permits experts to view the data 'live' and allows rapid diagnosis of any problems with the expected pile behaviour.

Jan 1, 2002

By Erik M. Westerberg

The Soilex Pile combines a slender shaft, for quick and easy installation, with an enlarged pile toe, for high capacity. The key component is the Expander Body, which is inflated by injecting cement grout when in position. The latest development in the Soilex Pile System results in a reduction of the total cost of Soilex Piles, in many cases values that are competitive with pre­cast concrete piles and displacement piles. Soilex Piles can now be installed on top of a bearing soil layer, instead of 3 to 4 m into that soil as previously required, further minimising the ground disturbance. Soilex Piles achieve high capacity in relatively loose soils, with ultimate loads typically between 1000 and 2000 kN in a sand with CPT qc = 5 to 10 MPa or SPT N= 10 to 20. It is possible to pre-load and proof-load all piles with dynamic testing up to 2000 kN or using built-in jacks, thereby verifying the capacity. The vibratory installation method, which is extremely quick and causes very little soil disturbance and noise, is exemplified by two case histories.

Jan 1, 2000

By R. H. Wright

This paper describes the design philosophy and methods employed in constructing the foundation elements for the Little Britain Project in the City of London. The Contract is a design and construct package for the foundations of a 3-storey basement which will be built using "top-down" construction techniques and is to be carried out by Fairclough Piling and Marine on behalf of Wimgrove Nominees. The Project includes 8000 sq.m. of diaphragm wall and barrettes 139 No. large diameter piles ranging from 900mm to 3000mm in diameter and up to 45m deep, and 9 No. cruciform barrettes for the heaviest column loads. Major factors influencing the design of these foundations include differential settlement, heave analysis and a fast track construction approach. Little Britain will provide 43000 sq.m. of space in two linked buildings which will bridge a new road joining London Wall to Newgate Street. The foundation contract is well advanced and the building is due for completion in the Summer of 1990.

Jan 1, 1989