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By Walid El Kamash, Sadik Oztoprak

"Soft soil presents a challenge against multistory buildings in some cities of Egypt such as Port Said due to the consolidation settlement. Deep mixed (DM) columns are used to improve the soft foundation soil in order to reduce the total and differential settlements. Latest research revealed that this improvement technique also increases the rate of mechanical consolidation due to column yielding caused by stress concentration from the soft soil. In this study, extended poly-styrene (EPS) Geofoam is used to replace the soft soil over DM columns in order to control the stress concentration and settlement. To understand the effect of EPS geofoam on the degree of consolidation, stress concentration and settlement, a parametric study was carried out through a mechanically and hydraulically-coupled numerical method. A unit cell model is used, in which the soil was considered linear elastic; DM column and EPS Geofoam are elasticplastic materials. Results reveal that EPS geofoam is helpful for reducing the settlements and accelerating the consolidation. Increasing the length of the column of the deep mixed foundation with EPS geofoam has a significant effect on accelerating the consolidation.INTRODUCTIONExpanded polystyrene (EPS) geofoam is a lightweight polymeric material which is made by expansion of raw plastic beads. The expansion of the EPS beads are spherical-shaped particles containing closed hollow cells. EPS which plays an important role as an innovative lightweight construction material is now well recognized due to its low density in addition to high compressive and rupture strength. Inglis (1996) reported the first use of EPS geofoam as a seismic buffer to reduce potential seismic loads against a nonyielding basement wall. Gaskin (2000) and Bathurst et al. (2007) carried out reduced-scale shaking table test on a rigid retaining wall protected by EPS geofoam. The test data showed that the peak lateral loads acting on compressible model walls were reduced below values measured for nominally identical structure but with no compressible inclusion. Abdelrahman and El Kamash (2014) investigated the behavior of EPS Geofoam beneath raft foundation on soft soil of Port Said. They showed the ability of EPS to control vertical displacements. The investigation of the behavior of EPS geofoam with DM column has not attracted more attention of previous researchers. In this paper, the behavior of replacing the soft soil by EPS geofoam was examined in the presence of DM column."

Jan 1, 2015

By Federico Pagliacci

Continuous Flight Auger (CFA) technique represents an important technological advance in the construction of piles in soft soils. The possibility of excavation under the water table with no need for drilling fluids, along with high productivity, have resulted in this technique?s becoming widespread in many countries. However, CFA technology has limitations because of its difficulty in penetrating hard layers and cross strata with cobbles and boulders. In these situations, pile verticality may be an additional problem. The Cased Augered Pile (CAP) technique consists of penetrating the soil with an auger housed in a casing. Two independent rotary heads sliding along the rig mast operate the auger and the casing. By adjusting the height of the casing shoe and auger bit according to soil type, it is possible to drill piles in very severe conditions - in the presence of cobbles and boulders - and to socket the pile into the rock. The use of a steel casing enables improved pile verticality. Therefore, the CAP technique is also used to construct secant piles to be used as diaphragm walls. The limitations of this technology are the depth, usually no more than 27 m (88 feet), and the size of the rig that supports the drilling tool, no less than 70 t (77 short tons) in working conditions. This paper illustrates CAP technology, the drilling system, and the characteristics of concrete and steel reinforcement and offers a case study of the Palermo-Carini second railway line, which used CAP to construct the new 30 km (18.6 mi) railway line, 20 km (12.4 mi) of which passes through the very congested downtown area of Palermo. More than 300,000 m (186.4 mi) of piles have been drilled in dense calcarenite formations with unconfined compressive strength of 15-25 MPa (2,200-3,600 lb/inch2), soft clay, and silt formations.

By Federico Pagliacci

Continuous Flight Auger (CFA) technique represents an important technological advance in the construction of piles in soft soils. The possibility of excavation under the water table with no need for drilling fluids, along with high productivity, have resulted in this technique’s becoming widespread in many countries. However, CFA technology has limitations because of its difficulty in penetrating hard layers and cross strata with cobbles and boulders. In these situations, pile verticality may be an additional problem. The Cased Augered Pile (CAP) technique consists of penetrating the soil with an auger housed in a casing. Two independent rotary heads sliding along the rig mast operate the auger and the casing. By adjusting the height of the casing shoe and auger bit according to soil type, it is possible to drill piles in very severe conditions - in the presence of cobbles and boulders - and to socket the pile into the rock. The use of a steel casing enables improved pile verticality. Therefore, the CAP technique is also used to construct secant piles to be used as diaphragm walls. The limitations of this technology are the depth, usually no more than 27 m (88 feet), and the size of the rig that supports the drilling tool, no less than 70 t (77 short tons) in working conditions. This paper illustrates CAP technology, the drilling system, and the characteristics of concrete and steel reinforcement and offers a case study of the Palermo-Carini second railway line, which used CAP to construct the new 30 km (18.6 mi) railway line, 20 km (12.4 mi) of which passes through the very congested downtown area of Palermo. More than 300,000 m (186.4 mi) of piles have been drilled in dense calcarenite formations with unconfined compressive strength of 15-25 MPa (2,200-3,600 lb/inch2), soft clay,

Jan 1, 2017

By Adrian Mercer, Ashkan Ameri

Due to general degradation, increased traffic levels, and historical ground movement, this road and rail bridge which provides an essential link between the interior of the country and the Port of Abidjan, required significant repair and reinforcement. This included strengthening the pre-stressed concrete box girders and replacement of the existing bored pile foundations. Replacement piles had to be adjacent to, and no longer than, the existing piles, in order to not compromise the stability of the operational bridge during the works. The underlying geology, however, meant that the pile loads had to be predominantly transferred into the ground through end bearing. Rather than installing a greater number of piles or larger diameter piles, innovative thinking changed the usual mind-set of designing the piles to the prevailing ground conditions, to designing the ground conditions to suit the piles. Jet grouted columns were installed beneath the toes of the new piles to increase the bearing capacity of the ground. This significantly contributed to the sustainability of the project and reduced carbon emissions through saving concrete, steel, plus transportation and disposal of spoil.

Sep 8, 2021

By Donald Deardorff

"Helical piles often rely on the final installation torque for ultimate capacity verification. When helical piles are designed using traditional bearing capacity equations for deep foundations and field monitored for a specified final installation torque, a factor of safety equal to 2 is often allowed for the design. One of the more common methods of determining torque during helical pile installation is by correlating the differential pressure across a hydraulic gear motor to a torque. Most drive head manufacturers provide multipliers to convert differential pressure to torque for different drive head models. These multipliers are based on theoretical torque equations and vary with the planetary gear ratio, hydraulic gear motor displacement and drive head efficiency. Drive head manufacturers show a linear fit between the differential pressure and output torque with no scaling effect. Previous drive head testing performed by the author has confirmed that the drive head differential pressure to torque relationship is generally linear however there is a scaling adjustment needed. This results in a variation of multipliers across the differential pressure range for a given drive head.Eight hydraulic drive heads from three manufacturers were field tested by Foundation Supportworks, Inc. to compare the torque versus differential pressure curves with varying installation equipment, hydraulic line sizes and hydraulic flow rates. Differential pressure was monitored using three methods including pressure gages, PT-Tracker and an Ashcroft AT-100. Flow and temperature was measured using a Webtech system analyzer. Torque was measured using a Pro-Dig in-line torque transducer, a TruTorque indicator and a Chance Mechanical Dial in-line torque indicator. The current testing indicates that a change in installation equipment and/or a change in hydraulic flow rate may affect the torque versus differential pressure curve of a given drive head. The results of this testing also show that some of the methods for determining torque during helical pile installations may be unconservative, thereby resulting in safety factors less than required."

Jan 1, 2017

By Donald Deardorff

Helical piles often rely on the final installation torque for ultimate capacity verification. When helical piles are designed using traditional bearing capacity equations for deep foundations and field monitored for a specified final installation torque, a factor of safety equal to 2 is often allowed for the design. One of the more common methods of determining torque during helical pile installation is by correlating the differential pressure across a hydraulic gear motor to a torque. Most drive head manufacturers provide multipliers to convert differential pressure to torque for different drive head models. These multipliers are based on theoretical torque equations and vary with the planetary gear ratio, hydraulic gear motor displacement and drive head efficiency. Drive head manufacturers show a linear fit between the differential pressure and output torque with no scaling effect. Previous drive head testing performed by the author has confirmed that the drive head differential pressure to torque relationship is generally linear however there is a scaling adjustment needed. This results in a variation of multipliers across the differential pressure range for a given drive head. Eight hydraulic drive heads from three manufacturers were field tested by Foundation Supportworks, Inc. to compare the torque versus differential pressure curves with varying installation equipment, hydraulic line sizes and hydraulic flow rates. Differential pressure was monitored using three methods including pressure gages, PT-Tracker and an Ashcroft AT-100. Flow and temperature was measured using a Webtech system analyzer. Torque was measured using a Pro-Dig in-line torque transducer, a TruTorque indicator and a Chance Mechanical Dial in-line torque indicator. The current testing indicates that a change in installation equipment and/or a change in hydraulic flow rate may affect the torque versus differential pressure curve of a given drive head. The results of this testing also show that some of the methods for determining torque during helical pile installations may be unconservative, thereby resulting in safety factors less than required.

By Richard Stone, Rouzbeh Afsharhasani, Moses Karakouzian

"Caliche, a hardened sedimentary deposit of calcium carbonate that occurs worldwide, generally in arid or semiarid regions, is frequently encountered in Las Vegas, Nevada. The presence of a caliche layer in a soil profile affects the response of deep foundations to axial load. This paper studies the stiffening effect of caliche layers on the elastic settlement of a pile foundation. In order to evaluate the response in a layered soil-caliche profile, finite element analyses were performed on a typical-sized single pile and a pile group, both having constant diameter and length of the pile. The results indicate that the stiffening effect from the caliche is noteworthy, and a layer with a relative thickness of at least one pile width, regardless of its location, reduces the pile settlement for both single piles and group of piles systems by at least 50%.IntroductionThe presence of cemented materials in the soil profile influences the settlement response of foundations. One type of cemented material that can be found in arid places around the world is a sedimentary deposit of calcium carbonate called caliche. Caliche, a hardened sedimentary deposit of calcium carbonate, is common in arid and semi-arid urban areas, such as Las Vegas, Nevada (Wyman, et al. 1993).Caliche is mostly observed in lacustrine, river, and alluvial fan deposits (Jr.C.C 1970). It is also found in Central and Western Australia, the Kalahari Desert, the High Plains of the Western U.S., and the Sonoran Desert of the U.S. and Mexico.Some conditions required for the formation of caliche are that country or basement rocks must be a carbonate type, carbonate must be present in the soil zone of the area, climate regime is semi-arid to arid, there exists widespread capillary activity, and carbon dioxide (CO2) is present in the environment. As a result, caliche occurs as a product of the carbonization process (Atabey, Atabey and Kara 1998). In such areas where foundations are constructed on thin rock layers (caliche), special geotechnical design conditions should be considered, particularly if the supporting rock layer is underlain by a weaker material."

Jan 1, 2015

By Kamil Nuzha, Jianchao Li, Bashar S. Qubain

"The Philadelphia Water Department is rehabilitating Belmont Raw Water Basin. As part of this work, a 500-ft long, temporary cofferdam was designed to retain 35 ft of combined water and soil at the western half during the reconstruction of the eastern half. A cofferdam that comprises two integral rows of sheet piles was selected to take advantage of the soil’s weight between the sheet piles for increased stability. To fine tune the design, a geotechnical investigation was carried out to verify the subsurface conditions and, in particular, the top of rock variations along the centerline of the cofferdam. A detailed finite element analysis was performed based on the subsurface findings and incorporating the construction sequence to evaluate the behavior of the cofferdam at the following stages: installation of tie rods to connect to the two rows of sheet piles; partial excavation and installation of tiebacks; complete excavation of the east basin, and demolition of the cofferdam. Inclinometers and survey markers were installed every 100 ft along the cofferdam and were monitored throughout construction. The deformation measurements were in good agreement with the finite element results.INTRODUCTIONThe Philadelphia Water Department (PWD) Belmont Raw Water Basin is located at the intersection of City Line and Belmont Avenues in Philadelphia, PA. The facility actually contains two raw water basins, east and west, separated by an earthen dividing dike. Water leakage at the bottom of the basins and through the dividing dike together with increasing demand for a larger storage capacity dictated the replacement of the wide earthen dike with new narrower concrete structure. The temporary cofferdam was designed for a two-year period to facilitate excavation support, water cutoff, removal of the existing earthen dike and replacing it with a new concrete dike. During this construction sequence, the water level in the west basin had to be maintained at or near its full capacity.Various excavation support systems were considered for this project prior to the selection of a double wall sheet pile cofferdam. Fig. 1 shows a plan view of the cofferdam and the new dividing dike. A typical cross section of the two structures is shown in Fig. 2. Double row sheet pile walls are commonly used as both temporary and permanent retaining systems in open water applications such as construction works, quaywalls, breakwaters and revetments for storing industrial waste as indicated by Ohori, et al. (1984), Ohori et al. (1988), and Khan, et al. (2001). There are many advantages to double row sheet pile systems as recognized by Ohori, et al. (1984; 1988): (1) It can be installed and removed in the presence of water easily and quickly; (2) it provides stability with small width to height ratio, utilizing the existing soils between the installed sheet pile rows; and (3) it serves well as a means for water cutoff. These advantages meet the specific project requirements."

Jan 1, 2016

By Alexander Scheuermann, Martin D. Larisch, David J. Williams

"Drilled displacement piles (DDP) have been used around the world for decades as foundation elements for structures and embankments. Typically the pile toes are designed to penetrate into stiff or dense soil formations to achieve sufficient base resistance. Recent research at The University of Queensland in Brisbane, Australia has discovered that the in situ stress conditions in stiff to hard clays is directly related to pile installation rates, which in turn are a function of the piling rig capacity and ground conditions. With adequate and constant pile penetration rates in situ stress conditions in the stiff to hard clay are increased by about 40%, resulting in significantly higher pile capacities. If pile penetration rates are too slow the in situ stress conditions are reduced considerably by remoulding and shearing of the clay, potentially causing reduced pile capacities. The paper presents the results of full-scale test piles at a stiff to hard clay site installed using different full-scale piling equipment.INTRODUCTIONDrilled displacement piling (DDP) is a piling technique in which a hollow stem, fitted with a purpose built displacement tool at the bottom, is drilled into the ground. Dissimilar to non-displacement piles, like Continuous Flight Auger (CFA) piles or conventional rotary bored piles drilled with kelly bars, the soil is not excavated during the DDP penetration process, but is displaced laterally and to a lesser extent vertically. The cavity created by the drilling tool is filled with highly workable concrete during the extraction process. The DDP technique is very economical providing high production rates and creating only marginal drill spoil, which has led to its increased global usage during the last decade. The typical DDP installation process is described in Figure 1."

Jan 1, 1900

By Dr. Anup Kumar Mandal, Partha Roy, Shuvranshu Kumar Rout, Dipak Mandal, Biswajit Das

Installation of a new scalping station with bunker, apron feeder, scalping screen, ramp -retaining wall and approach bridge was planned in an existing integrated complex of phosphate fertilizer at a remote place in West Africa. Rock phosphate ROM, transported from mines by a combination of 100 Ton and 150 Ton dumper, would be fed to a steel bunker having capacity of 180 m3. Different options were studied for retaining wall at the junction of ramp and approach bridge. Initially options with conventional RCC Retaining Wall, Gravity Retaining Wall with Precast Concrete Blocks and Reinforced Earth walls were studied. Option with Reinforced Earth was selected as this option was much more cost effective compared to other options. But real engineering challenges cropped up when competent execution contractors were not available nearby the site. To minimize the cost, an innovative option with Stepped Retaining wall was then studied. Geotechnical parameters of native soils, selected for the construction of the approach ramp were determined and it was found that with available poor geotechnical parameters of the native soils, design of stepped retaining wall would not be feasible with respect to available bearing capacity, subjected dead load, live load, operational load and earth pressure. A conscious effort was then made to make the design feasible by improving the geotechnical parameters of the retained earth of ramp near the retaining wall. In view of that, mix design with locally available materials like Silexite, Sand, Laterite, Gravel and Silt at different proportions was made and samples were tested in the laboratory to determine relevant geotechnical parameters. Based on the test results, a suitable mix was selected that had high shear strength, enhanced bearing capacity and improved coefficient of earth pressures. Design of stepped retaining wall was then made with the selected construction materials and construction completed. The plant was successfully commissioned in December. 2021.

Sep 1, 2022

By Karen Dawson

This paper presents a case study of the deformation-based design, construction, and performance of stone column ground improvement (GI) beneath a mechanically stabilized earth (MSE) wall and bridge abutment with heights up to 50 feet. As part of the widening of Interstate 5 (I-5) to allow High Occupancy Vehicle (HOV) lanes in Tacoma, Washington, a new approach and span over the Puyallup River will be constructed. During the soils investigation and design phase of the project, low plasticity silts (ML) inter- bedded with silty sand layers and organic silt where identified as being potentially liquefiable. Stone column ground improvement was designed using a deformation-based approach to address static settlement and seismic stability of the proposed MSE embankments. The deformation-based design of the stone columns resulted in significant savings over a limit equilibrium-based approach. This paper presents the results of sonic coring taken from the initial stone columns installed and compares these results to the real-time data acquisition reports from the stone column installations. Vibration monitoring results during stone column installation are included. Settlement monitoring at the face of the MSE wall and buried vibrating wire settlement monitoring elements are presented and compared to the original settlement predictions.

By Dominic Parmantier, Karen Dawson, Suthan Pooranampillai, Seungcheol Shin

"This paper presents a case study of the deformation-based design, construction, and performance of stone column ground improvement (GI) beneath a mechanically stabilized earth (MSE) wall and bridge abutment with heights up to 50 feet. As part of the widening of Interstate 5 (I-5) to allow High Occupancy Vehicle (HOV) lanes in Tacoma, Washington, a new approach and span over the Puyallup River will be constructed. During the soils investigation and design phase of the project, low plasticity silts (ML) inter- bedded with silty sand layers and organic silt where identified as being potentially liquefiable. Stone column ground improvement was designed using a deformation-based approach to address static settlement and seismic stability of the proposed MSE embankments. The deformation-based design of the stone columns resulted in significant savings over a limit equilibrium-based approach. This paper presents the results of sonic coring taken from the initial stone columns installed and compares these results to the real-time data acquisition reports from the stone column installations. Vibration monitoring results during stone column installation are included. Settlement monitoring at the face of the MSE wall and buried vibrating wire settlement monitoring elements are presented and compared to the original settlement predictions.IntroductionStone column ground improvement was implemented as a means of supporting mechanically stabilized wall approaches for a new bridge over the Puyallup River, part of HOV improvements to I-5 in Tacoma, Washington. The work discussed in this case history was part of the Washington State Department of Transportation (WSDOT) I-5/Portland Avenue to Port of Tacoma Road, Stage 1 Northbound HOV contract, developed as an early work element to a follow-on bridge construction project. The area requiring stone column ground improvement is shown in Figure 1. The improved ground supports permanent geosynthetic walls and embankments up to 50 feet high. This wall can be seen in Figure 1. The selected ground improvement primarily provides global stability of the soils beneath the walls during anticipated seismic loading and also reduces the time and magnitude of consolidation settlement under the weight of the planned embankment.Approximately 74,000 cubic yards of liquefiable alluvial soils were improved by stone columns. Stone column construction occurred in late 2010 and early 2011. This was followed by the embankment and wall construction. Settlement monitoring began with the embankment construction and continued into 2012."

Jan 1, 2017

By M. Hesham El Naggar, Tony Sangiuliano, Alper Turan

"Bridge abutments supported on pile foundations are often constructed over weak and compressible soils. The consolidation settlements induced by the embankment loads are known to result in downdrag and lateral forces on the piles supporting the bridge abutments. The performance of a pile group including inclined piles embedded in consolidating soils was investigated numerically considering surcharge loads from approach embankment construction. A two-dimensional numerical model was constructed using commercial finite element software PLAXIS and calibrated against field measurements of the abutment movements observed on Brookdale Avenue Underpass Structure located on the Macdonald-Cartier Freeway in Ontario between Cornwall and the Quebec border. The soft soil model (SSM) was used to simulate the constitutive behavior of the compressible soil deposit. The SSM model parameters were determined based on the laboratory tests. Subsequently, time dependant development of downdrag effects was comparatively evaluated for vertical and inclined single piles as well as a pile group that included both vertical and inclined piles.Results showed that drag loads increased with the consolidation time. However, majority of accumulation of drag loads took place within first 120 days after installation of piles. The results also indicated that the shear forces and bending moments are controlled by the lateral spreading of foundation soil and their accumulation is proportional to consolidation time. The large axial strains caused by large downdrag forces are considered to have yielded the piles and this is a possible reason for unusual abutment movements. The results presented in this study are considered to be of interest to researchers and practitioners.1. IntroductionDeep foundation units are widely used for supporting bridge piers and abutments, where weaker surficial soils preclude shallow foundations. Particularly in Ontario, semi-integral and integral abutment bridges are typically supported on end-bearing steel driven piles. The construction of approach embankments over weaker, compressible soils results in significant vertical and lateral soil movements, which induce additional loads on piles supporting the abutments. In order to minimize such effects, preloading and surcharging are commonly employed approaches to avoid unanticipated settlements prior to the installation of piles. Other alternatives such as aggregate pier supported approach embankment are also being studied as the schedule restrictions imposed by preloading and surcharging becomes cost prohibitive (Turan et al. 2012)."

Jan 1, 2015

By Masaki Kitazume

Five papers were presented orally to the topics of Jet Grouting and Deep Mixing. The session was started with a brief introduction by the moderators. Following the oral presentation, floor discussions were directed by the moderators. A brief introduction of each of the oral presentations is provided before each discussion.

Feb 10, 2003

By Salim Mezazigh

Usually different methods for designing a single pile submitted to a lateral loading are available. They are based on theory of elasticity with the parameters E,v or subgrade reaction method using the p-y curves. The subgrade reaction methods are commonly used. They allow determining the efforts exerted along the piles and their corresponding displacements. Before any design the reaction curves P-y must be well defined for each foundation soil layer. These curves link the pile horizontal displacement y to the subgrade reaction of soil P. Different in situ tests such as the static penetrometer or the pressuremeter give a possibility to get the P-y curves in the case of a single pile installed in sand with an horizontal surface and statically laterally loaded. These ideal conditions are not always respected on the site around the pile if appear slopes, embankments, or buildings... The behaviour of such configurations of piles is more sophisticated due to the proximity ( slope, embankment, earthworks, buildings,..). A research program has been conducted to determine the influence of a slope on the P-y curves by centrifuge modelling. The centrifuge tests constitutes an experimental approach allowing parametric studies in respect with similitude laws in geotechnique. Before all, repeatable tests have demonstrated that the test conditions, the instrumentation equipment and the installation method for piles are well controlled. By this way, the obtained results from centrifuge tests can be transferred to the prototype i.e. the in situ piles. Many tests have been performed on piles in sand to determine the influence of a pile on the p-y curves. The main objective is to give for practice some coefficients to apply to p-y single pile curve to take into account the proximity slope effect. Here the experimental set up is described and in particular the proximity slope effect is discussed. Deduced subgrade reaction reduction factors are proposed for piles in sand under lateral loading.

Jan 1, 2002

By Ana Pereira, Naomi Norris, Donald Bruggers

The city of Christchurch, New Zealand is predominantly founded on alluvial sediments consisting of interbedded layers of loose to medium dense sand, soft to stiff silt and clay mixtures, and pockets of organics. These soil deposits have high liquefaction potential. Following the 2010/2011 Canterbury Earthquake Sequence several ground improvement trials were undertaken within Christchurch to understand the effectiveness of different types of ground improvement in these silty sand geological conditions. This paper presents a discussion of a stone column ground improvement trial undertaken at a Christchurch site with high fines content soils. Stone columns were installed using two types of installation methods and a range of Area Replacement Ratios (ARR) to assess the effectiveness of these ground improvement methods in high fines content soils as well as the influence on the type of installation method. Pre- and post-column installation CPTs, seismic Dilatometer Tests (sDMTs), cross-hole shear wave velocity tests, and plate load tests have been undertaken to assess the effectiveness of the ground improvement. Results of the testing are presented in this paper. INTRODUCTION This paper presents the results of a stone column ground improvement trial undertaken in Christchurch, New Zealand (Fig.1). In 2010 and 2011, four large earthquakes (greater than magnitude 5.9) and thousands of smaller aftershocks occurred in the greater Christchurch region. These events are referred to as the Canterbury Earthquake Sequence (CES). Liquefaction occurred across large portions of the city during the stronger earthquakes, particularly the February 2011 event. Following the CES a large amount of data was collected across the city including the location and volume of sand boils, and the location and magnitude of ground cracks. Additionally, data from thousands of ground investigations have been uploaded into a public database. As a result, there is clear evidence that silt and silty sands liquefy in addition clean sands. The CES and resulting liquefaction motivated a series of studies and trials from different organisations aiming to better understand the available technologies for liquefaction mitigation. The subject of this paper is a ground improvement trial undertaken by a local contractor specialising in deep foundations and ground improvement. They were interested in understanding the effectiveness of stone column ground improvement in high fines content (silty) soils using two different installation techniques, vibratory and non-vibratory. Different arrays and Area Replacement Ratios (ARRs) were used for each of the two methods of columns installation.

Jan 1, 2019

By Nicolas Denies, Jeroen de Leeuw, Bart Lameire, Jan Maertens, André Vervoort, Flip Hoefsloot, Noël Huybrechts, Flor De Cock

"In recent years, the Deep Mixing Method has increasingly been applied for the construction of earth and water retaining structures. From practice, it has been experienced that there is a real need to develop execution and design rules adapted to the function of the soil mix wall (retaining wall, water barrier, foundation solution or a combination) including the temporary or permanent character of the application. Based on the results of the BBRI Soil Mix project (2009-2013), a design approach has been developed in collaboration with the SBRCURnet. The present paper briefly discusses the principles of this design approach which takes into account the function of the soil mix wall and the characteristics of the soil mix material. The interaction between the soil mix material and the steel reinforcement can be considered in the calculations depending on the function of the soil mix wall. Design and quality control requirements are given in function of the application and take the lifetime of the structure into account. Durability aspects of the soil mix material are therefore considered in the present design approach.INTRODUCTIONSince several decades, the deep mixing method is used for ground improvement works. A more recent application is the use of soil mix as structural elements such as in the case of the earth-water retaining soil mix walls. Since 2000, due to the economic and environmental advantages of the method, this particular application has shown an amazing growth in Belgium and in the Netherlands. A typical excavation (16 m depth), realized with CSM (Cutter Soil Mix) panels, is shown in Fig. 1. For temporary applications, the questions related to the mechanical characteristics of the material, its permeability and its adherence with steel have been investigated with success within the framework of the BBRI Soil Mix project (2009- 2013) (see Denies et al. 2012 for more details). The durability of the soil mix material remains a complex topic while permanent applications are more and more observed in practice. In order to define an obvious design approach, it was necessary to clarify the potential functions of soil mix walls and to establish the requirements related to their design and construction. The BBRI (in Belgium) and SBRCURnet (in the Netherlands) have therefore worked together to publish guidelines in the form of a handbook titled ‘Soil Mix Walls’ (publication foreseen in 2015). In this handbook, a methodology is proposed for the design of the soil mix walls for which the interaction between steel and soil mix can possibly be taken into account dependent upon the application. Each potential function of the soil mix wall is described (e.g. earth retaining wall, cut-off wall, etc.) and the temporary or permanent character of the application is always considered."

Jan 1, 2015

By Timothy Flaherty

We observed the boiling in the water very close to the water adjacent to where we were drilling. That only happened at the very beginning before it was switched to water flushing. Yes, it was performed with water flush.

Feb 10, 2003

By David White

When finished (projected completion in 2016) the Hong Kong-Zhuhai-Macau Bridge Project will comprise three cable-stayed span bridges and a 4.15 mile immersed tube tunnel - linking Hong Kong to Macau and the mainland Chinese city of Zhuhai. The design included two artificial Islands to serve as the transition structures for the tunnel to bridges, entailing a massive seaborne land reclamation project, and the use of thousands of sheet piles, and man-hours. The challenges of driving individual steel sheet in 100? of water are well known, let alone in the open waters of the South China Sea. In 2010 a joint effort between American Piledriving Equipment (APE) and Allnamics Pile Testing Experts convinced the Chinese contractor First Harbor Marine Group China that a massive multi-vibro hammer can be used to drive 130? long, 72? diameter steel pipe piles weighing 662 US tons each into the sea bed of the South China Sea for the Hong Kong - Zhuhai - Macau bridge artificial islands. Combining APE?s hammer design, production and operation know-how with the pile driving simulation and installation know-how of Allnamics made it possible to show the feasibility of driving these gigantic piles into bottom of the sea to the required depth.

By David White

"When finished (projected completion in 2016) the Hong Kong-Zhuhai-Macau Bridge Project will comprise three cable-stayed span bridges and a 4.15 mile immersed tube tunnel - linking Hong Kong to Macau and the mainland Chinese city of Zhuhai. The design included two artificial Islands to serve as the transition structures for the tunnel to bridges, entailing a massive seaborne land reclamation project, and the use of thousands of sheet piles, and man-hours. The challenges of driving individual steel sheet in 100’ of water are well known, let alone in the open waters of the South China Sea.In 2010 a joint effort between American Piledriving Equipment (APE) and Allnamics Pile Testing Experts convinced the Chinese contractor First Harbor Marine Group China that a massive multi-vibro hammer can be used to drive 130’ long, 72’ diameter steel pipe piles weighing 662 US tons each into the sea bed of the South China Sea for the Hong Kong - Zhuhai - Macau bridge artificial islands. Combining APE’s hammer design, production and operation know-how with the pile driving simulation and installation know-how of Allnamics made it possible to show the feasibility of driving these gigantic piles into bottom of the sea to the required depth.INTRODUCTIONThe challenges of driving individual steel sheets in deep water are well known, let alone in the open waters of the South China Sea. Often the challenges of construction are overcome with engineering or equipment. The challenges of China’s Hong Kong-Zhuhai-Macau Bridge, on the drawing board since 1983, were to overcome both. The challenges of overcoming the skepticism of the Chinese Engineering community would be another story.The finished project will comprise three cablestayed span bridges and a 4.15 mile immersed tube tunnel linking Hong Kong on an eastern span to the China mainland cities of Zhuhai and Macau via two western spans."

Jan 1, 2017