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By C. M. Haberfield

"1 INTRODUCTION Around the world, there is a demand for larger structures, tall buildings and large bridges. While good footing design is important for all structures, it is even more important in the case of large structures. Recent experience with footing design for tall buildings (e.g. Burj Al Alam development and Nakheel Tower in Dubai, the Gate of Kuwait in Kuwait, the City Centre Project in Bahrain and Eureka Tower and Freshwater Place in Melbourne) has shown the benefits of investing in footing planning, design and construction (Haberfield, 2011, Poulos and Bunce, 2007). The footing systems for most of these projects include the use of deep bored piles or barrettes (piles of rectangular cross-section). Many use piled rafts where the piles, while acting to support the load, are primarily used to reduce settlements. A clear understanding of the factors controlling the behaviour of the footing system is needed to enable a good engineering design to be achieved. This starts with a sound understanding of the ground characteristics and individual pile performance, including adequate collection of data and testing. The best footing solution can then be found using recent improvements in data collection and analytical techniques, complex and highly capable computer-based models and the availability of high speed computers. This paper focuses on the axial performance of deep bored piles socketed into rock – both their individual performance and their performance as part of a larger footing system. Recent research and construction practice is discussed. In practically all cases, serviceability conditions control the behaviour of the footings. Methods of establishing the parameters for input into sophisticated computer programs are described. Application of the methods to case studies is included and it is shown that the behaviour of individual piles can be closely predicted. These developments lead to lower construction costs, better constructability and shortened construction time because of the better understanding of footing behaviour. 2 FACTORS AFFECTING PERFORMANCE OF FOOTINGS ON ROCK For a typical pile-supported footing, it is necessary to consider both individual pile, pile group and raft performance. These require consideration of the behaviour of the ground immediately beneath the surface raft or footing, along the pile shaft, and at and beneath the pile toe (Figure 1). Immediately beneath the surface raft or footing, the important factors are strength for bearing capacity and stiffness for settlement and interaction effects. Along the pile shaft, of most interest are strength for bearing, excavatability and stability; stiffness for settlement and interaction effects; geology and permeability for pile stability and, most importantly, pile shaft resistance. At the pile toe all the above factors for the pile shaft are present and in addition the pile end bearing is of interest. Below the toe, stiffness for pile settlement is important to at least a depth of twice the building width."

Jan 1, 1900

By Dan Brown

Renewal and revitalization of transportation presents a challenge in the need for replacement, repair, and improvements of existing bridges, as well as increased construction of transit systems within existing transportation rights of way. Difficulties with conventional deep foundation systems occur because of the limited site access, adjacent structures, the need to maintain traffic, and other constraints on construction activity. Major projects are often performed in a design-build contract environment in which the schedule is aggressive, and where speed and reliability represent major considerations. Foundation designers are confronted with a need to solve problems with a construction-oriented mindset, where typical experience with lowest cost solutions may not reflect the most effective approach. This presentation presents an overview of the challenges that may affect design and construction of deep foundations in this environment and the methods that have successfully been employed on several large transportation projects in the U.S.

Jan 1, 1900

By Min Sunn Ye, Wei Wang, Huawen Xiao, Kai Yao, Fook Hou Lee, Siang Huat Goh

"Previous research have shown that introducing fibers to cement soil mixture is effective in improving the ductility as well as maintaining the strength of cement-treated soil. A good knowledge of stiffness of the improved soil at small strain is essential for realistic predictions of ground movements that may affect adjacent buildings or underlying infrastructure. This paper presents a triaxial system with local strain measurement developed for studying shear modulus degradation of cement treated clay with fibers. Cylinder specimens (70mm diameter by 140mm height) with 50% cement, 100% water, 0% to 1% polypropylene fibers by mass, and 7 days of curing period were used. A local strain measurement system with floating type miniature submersible LVDT is introduced in this paper. Configuration of the mounts including the pin size, length and distance are presented and discussed. Based on the experimental results, a reasonable configuration of the mounts is recommended for fiber reinforced cement treated clay. Results showed that the proposed local strain measurement system is effective for testing the shear modulus degradation of cement treated clay with fibers under both unconfined and confined condition. Comparisons with results from resonant column and bender element tests served to verify the reliability of the local strain measurements using the proposed method.INTRODUCTIONIn many geotechnical engineering problems, the operational strain domain ranges from 10-3% to 10- 1%. A good knowledge of stiffness at small strains is essential for realistic predictions of the ground movements that may affect adjacent buildings or underlying infrastructure. As such, during the last 3 to 4 decades, the importance of using the small strain stiffness of soils for the design of foundation and underground structures has widely been accepted. Triaxial testing has been widely used to study the stress-strain behavior of soil in the laboratory. However, the stiffness obtained from the conventional triaxial apparatus is usually far smaller than those back-calculated from field measurements. This is mainly attributed to the overestimation of axial strains from the external strain measurements, which usually includes compliance effects of the loading and load measuring system as well as sitting, bedding and alignment errors between sample and system (Baldi et al., 1988). The poor resolution of the external strain measurements is another important contribution. Therefore, conventional procedures are inappropriate for small-strain stiffness evaluation due to low accuracy and resolution."

Jan 1, 1900

By Andrew Middleton, Mark Wyatt

"The Brickworks Marketplace Project is a significant shopping centre development in inner north west Adelaide constructed by Badge Constructions in 2014 and 2015. The site was a former brickworks with a deep pit containing various extents of uncontrolled fill which was to remain on site, and with a remaining void up to 6 m in depth. The existing uncontrolled fill was improved using the High Energy Impact Compaction system, and the pit backfilled using a quarry crusher byproduct selected by trial and a recycled crushed concrete and bricks and compacted in deep lifts. This approach resulted in significant savings in compaction time, cost and building foundations. The settlements of various parts of the completed works have been monitored since February 2015 and this monitoring has demonstrated small settlements which meet the user’s constraints.INTRODUCTIONThe Torrensville Brickwork Markets project involved the transformation of a former brickworks and clay pit site into a regional 17,000m2 shopping centre, opening in June 2015.The site was a former brickworks with adjoining clay borrow pit. The clay pit had been partially backfilled over many years with ‘uncontrolled’ fill comprising ‘clean’ soil, bricks and kiln dust typically of the following thicknesses:??of the order of up to 7 m to 10 m but locally up to 15 m in the western part of the site??2 m to 5 m in the south-eastern part of the site; and??less than 0.5 m in the north-eastern part of the siteAnecdotal reports suggested compaction of some of the fill may have been undertaken, although this not able to be confirmed nor records obtained.Initially it was proposed to take up the existing uncontrolled fill, sort and recompact or remove to landfill, followed by backfilling in conventional means over 500,000 cubic metres of imported filling to a thickness of up to approximately 6m to backfill the former pit. This work represented a significant cost and was not economically viable.During early negotiations, the contractor proposed an alternative to retain and ground improve the existing filling on site, and to backfill the pit with fill placed and compacted in deep lifts, thereby significantly improving the economics, environmental and community impacts of the proposed works.The developer agreed to the proposal with the following performance criteria:??a settlement of =10 mm after 10 passes by the Impact Compactor (on existing subgrade areas);??a bearing capacity of 250 kPa for high level footings;??a maximum long term differential settlement of 40 mm (measured over 16 m), ie. 1 in 400; and??a minimum modulus of 40MPa."

Jan 1, 1900

By Sastry Putcha, Santosh Mummaneni, Swamy Avasarala, Vamshi Vemula

"This paper presents the results from a case study on the comparison of two strain acquisition instrumentation technologies, Geokon rebar strainmeters and Embedded Data Collectors (EDC) for the DC Water Main Pump Station project, in Washington D.C. These two instrumentation systems were installed by AVER in a single 18-inch (0.45 m) diameter augercast pile (with one-1.25 inch (3.175 cm) dywidag bar) at critical locations to determine the load transfer mechanism and establish a comparison between strain/load measured with these two systems along the pile. A quick static load test was performed on the test pile as per ASTM D1143 standard.Prior to the installation of the pile, a 24-inch (0.6 m) diameter outer casing was installed to the proposed cutoff elevation of -22.5 feet (-6.85 m) to discount the frictional resitance within the upper overburden zone. The pile was then drilled through the outer casing to the tip elevation of -65.02 feet (-19.8 m) with inner casing within the overburden zone. Strainmeters along with EDC were installed on dywidag bar at various locations and then wet set into the concrete following auger retrieval. The loads measured with EDC and Geokon sensors were within 15% percent of each other.PROJECT BACKGROUNDProject Background & Requirements:Like any other foundation piles, augercast piles are extensively used in the public and private sector structures in the United States for many years. It is a common practice to perform static compression (ASTM D1143), tension (ASTM D3689), and lateral load tests (ASTM D3966) depending on the project requirements. In recent years, embedded strain sensors, manufactured by Smart Structures, USA has gained prominence for its use to collect both static and dynamic measurements for driven piles. In addition, AVER has successfully used EDC for collecting long term static measurements for an abutment drilled shafts for I-95 Hotlanes project in Virginia, USA.Geokon sisterbar strain gages are widely used in the foundation industry to monitor the load transfer mechanism within pile foundations throughout the world. As the Geokon strainmeters are vibrating wire and are welded to a sister bar, there is often a debate within the engineering community with regards to what modulus to use when converting measured strains to loads. EDC sensors, unlike Geokon strain gages are embedded directly into the concrete and therefore do not have the same concern."

Jan 1, 1900

By J. Gniel, L. King, C. Gaudin, C. O’Loughlin

"This paper presents some recent advancements in centrifuge modelling, which enable the installation of displacement piles to be performed in-flight while measuring ground responses. Details and results are provided from a series of experiments where 21 full-displacement piles were installed into a sample of consolidated kaolin clay at 40g. The piles were pushed into the sample at a constant rate of penetration, with installation reaction loads and pore pressures measured. Insight into the installation effects of the full-displacement piles was obtained by undertaking in-situ testing pre- and postinstallation of piles. The findings show that centrifuge testing has the potential to play an important role in furthering the current understanding of displacement pile behaviour and installation effects.INTRODUCTIONDisplacement piles and displacement ground improvement columns cause soil to undergo significant distortion and shearing during installation, which alters the soil properties. It is essential to consider these changes in soil properties to estimate the behaviour of pile foundations with higher degree of accuracy. However, the installation effects of displacement piles are widely considered as one of the most difficult geotechnical mechanisms to model, both analytically and numerically, and experimental data is needed to advance the current state of knowledge.Theories, analytical and semi-analytical, have been developed to describe the displacement pile installation process. Randolph et al. (1979) applied the cylindrical Cavity Expansion Method (CEM) to model the installation of a displacement pile in a fine grained cohesive soil. However, cylindrical CEM only considers the field variables in radial coordinates, and hence the soil-pile interface can only be modelled as a frictionless material. Baligh (1985) introduced the Strain Path Method (SPM), which assumes soil flows around the tip of a displacement pile. SPM was shown to model the stress and strain fields, particularly within close proximity to the pile, more accurately compared to the cylindrical CEM. While these methods account for the installation effects of a displacement pile and can be used to estimate a resulting ultimate bearing capacity, they are unable to describe the load-settlement behaviour of such piles. With the added complexity of group effects, existing analytical methods do not provide a means to accurately calculate the ground response to the installation of a group of displacement piles in a cohesive soil.The advancement of computational power, numerical techniques and constitutive models has improved the accuracy of numerical analysis, particularly in regard to modelling pile installation. However, even with advanced techniques, Finite Element Method (FEM) suffers a number of disadvantages due to the large deformations, which results in mesh distortion and tangling. Mesh-free methods such as Discrete Element Method (DEM), Smoothed Particle Hydrodynamics (SPH) and Material Point Method (MPM) are the next generation of computational techniques that are able to deal with large deformation problems. However, these advanced techniques are computationally expensive, complex and yet to be incorporated into commercial packages. Such methods are considered to still be in the development stage and are yet to provide a complete solution to pile installation problems."

Jan 1, 1900

By Stuart Coutts

"This paper presents an overview of the author’s experience related to the assessment of the base capacity of straight shafted and enlarged-base bored piles in sand. A design approach based on CPT qc is described which has been calibrated using a database of load tests. The importance of correct installation techniques with instrumentation are illustrated and a discussion is presented on the current use of high strain dynamic testing to validate compliance with design. An example of a recent project with high quality instrumented load test data illustrates the close match to the proposed best practice approach and also highlights the importance for consideration of the effects of stress relief for deep foundations installed in deep excavations.1 INTRODUCTIONContinuous Flight Auger (CFA) piles are the bored foundation pile of choice for sand deposits across Australia. The evolution of the determination of the base resistance of CFA piles has been shaped by available investigative techniques, calculation methods, and calibration of designs with laboratory and field testing. The Cone Penetration Test (CPT) has been widely used in Western Australia (WA) where the test has been commercially available via multiple contractors for more than 25 years. On the East coast, the adoption of CPT testing has been slower with a transition from traditional Standard Penetration Testing (SPT) still occurring. Dynamic pile load tests are often used to derive parameters. The influence of pile installation on performance is commonly misunderstood and is an important element on any discussion of pile capacity for CFA pile types. The interface between the base of the constructed pile and the in-situ soil has an influence on capacity such that a poorly constructed pile base will have limited (if any) contribution to pile performance within the normal working range, generally within a 10 mm movement. The research presented in this paper pertains to CFA piles (no drilling fluids) and enlarged base piles constructed using CFA techniques under drilling fluids such that clean pile/base interface is targeted. Developments in modern piling equipment and instrumentation allow the pressure and volume of delivered concrete/grout to piles to be accurately monitored at various stages of installation such that repeatable ‘best practice’ can be achieved. The changes in soil conditions that occur due to the disturbance of the install technique are also important.Although the results of this research are likely applicable to bored piles, the interface between the pile and in-situ soil (shaft and base) need to be considered for various installation techniques. The effects of stress relaxation (due to removal of soil above pile base and adjacent shaft), time to concreting, and the zone of disturbed soil around the pile shaft are paramount.2 INSTALLATION CONSIDERATIONS The pile mix (concrete/grout) and interface with the in-situ soil are also an important consideration. For example, coarse grained, poorly graded, dry, clean sand will be partially permeated by most pile mixes; such that the influenced soil will be enhanced and in instances the overall effective pile dimensions increased. Permeation of the disturbed zone of a pile or anchor shaft along with scale effects (Lehane 2009) can have significant effect on shaft capacity and shaft frictions significantly exceeding expected are not uncommon based on ‘theoretical’ dimensions. Advancements in mix technology and mix techniques also have a large influence on the pile/soil interface. The ability of the piling rig and augers to excavate a plumb and gauge hole can also have a large influence on the zone of soil disturbed adjacent the constructed pile with a resulting influence on capacity."

Jan 1, 1900

By Mohammed Faizal, Abdelmalek Bouazza

"The operation of ground source heat pumps combined with foundation piles can have an effect on the thermal behaviour of the pile and the surrounding soil. This paper presents the effects of continuous heating, continuous cooling, and alternate heating and cooling operations on ground and pile temperatures as well as the thermo-mechanical behaviour of a field scale energy pile. The effect of pile operation on the ground temperatures is highest near the pile and reduces with increasing radial distance. The results of the present studies generally showed that the thermal elasticity of the pile is not affected.INTRODUCTIONGeothermal energy piles are foundation piles used as underground heat exchangers to maintain thermal comfort in buildings, via the use of ground source heat pumps (GSHPs). Ground source heat pumps are more economical and environmental friendly compared to conventional heat pumps. Energy piles can be combined with supplemental surface heaters or coolers, known as hybrid systems, for forcefully recharging the ground during non-operational times of the GSHP. Alternative heating and cooling of the GSHP improves geothermal energy usage and alleviates heat build-up in the ground and provides a balance of ground temperatures around the heat exchanger (Jalaluddin and Miyara, 2012).The temperatures induced in the piles during GSHP operation can lead to a complex response of thermal strains and stresses in the pile concrete. An assessment of the thermo-mechanical response of energy piles for various thermal loads may assist engineers in the design process. Furthermore, an assessment of ground temperatures will also highlight any potential thermal interactions with other energy piles in actual building operations.At present, the thermal strain and stress distribution in field scale energy piles has mostly been studied for continuous operation (Laloui et al., 2006; Bourne-Webb et al., 2009; McCartney and Murphy, 2012; Akrouch et al., 2014; Mimouni, 2014; Murphy and McCartney, 2014; Murphy et al., 2014; Wang et al., 2015). These studies have contributed considerably to the understanding of the axial thermal strain and stress distributions in the piles and have shown that pile thermal behaviour is mostly thermo-elastic without inducing major structural concerns.The present paper adds to the current knowledge by assessing the pile thermo-mechanical and ground thermal response for continuous and alternating thermal loads of a field scale energy pile. The operation modes studied are 24 hours continuous cooling (Faizal et al., 2015), 24 hours continuous heating, (Wang et al., 2015) and alternate heating and cooling operation (Faizal and Bouazza, 2016). The forced ground thermal recharging is done during the non-operating times of the cooling unit, simulating a solar hybrid GSHP system for a scheduled intermittent mode of operation."

Jan 1, 1900

By Gang Guo, Zhong Liu

"In response to an increasing demand of anchored structures for underground space and transportation infrastructure in China, an innovative underreamed ground anchorage system was created. The novel anchorage system has provided more efficient functions with higher capacity at lower cost, because of the enlarged cylindrical body (known as ECB) sealed in capsule at bottom of anchorage. This paper presents the detailed structure of innovative anchorage system and its special features. To investigate the bearing mechanism of new anchorage, we evaluate its performance and failure mode based on the experimental results, and also indicate its strain-hardening load-displacement relationship. Unlike the shaft anchorages, it is identified no overall failure to be found in soil surrounding the underreamed anchorage. More importantly, the anchorage capacity is governed by the base resistance, which takes more than 80% of total pullout capacity resulting from the contribution of ECB. Finally a case history of anti-floating project introduces the new combined construction approach and procedure, which has provided the contribution to the quality control and cost efficiency.INTRODUCTION AND BACKGROUNDThe construction boom over two decades in China has resulted in an increasing demand for underground space and slope stability. The infrastructures market requires the more efficient anchorage systems for retaining structures, resisting uplift forces and slope protection. The major concern focuses on gaining higher capacity and lower cost resulted from perfecting anchorage systems. There are three main anchorage systems designed to achieve the above objectives: ? single bore multiple anchorage system (Barley 1997), ? regroutable anchorage system (Smoltczyk 1991), ? underreamed anchorage systems (Xanthakos 1991). Generally, the concept ? comparing with the other two, can be more competitive due to its distinct advantages. To improve the performance and durability of ground anchorages under the complex geological conditions and diversified engineering requirements, a number of different underreamed anchorage technologies had been used, which included cone - shape anchorage described by Liao, Wu and Shu (1997) in Taiwan, Soilex anchorage developed in Sweden (Massarsch et al. 1997), Soletanche anchorage proposed in France, blasting anchorage used in Czechoslovakia (Hobst and Zajic 1986), jet-grouting anchorage innovated in Europe (Anon 1988), as well as deep mixing anchorage created in Japan (Cheng et al. 2000).The underreamed anchorage systems have the remarkable advantages compared to the shaft anchorage system. However, there are also some weaknesses inherent in the underreamed systems. For instance, the mechanical underreamed anchorage is unsuitable in sand or waterbearing ground, because the enlarged hole is easy to collapse, and it is hard to ensure the quality of anchorages. On the other hand, relying on the blasting in deep hole, the geometrical space and dimension of enlarged hole is uncontrollable, meanwhile, the continuous blasting operations may easily cause the serious ground deformation and the negative effects to the completed anchorages."

Jan 1, 1900

By Bruno Vingiani, Alessandro Bertero

"The use of Artificial Ground Freezing (AGF) for temporary soil strengthening and seepage control is an effective alternative to grouting when dealing with soils whose degree of finesses would imply the use of highly expensive chemical grouts. However, compared to grouting, the application of this improvement technique usually needs a more accurate preliminary soil investigation campaign and a design assisted by specific calculation software. Besides a general description of the main features of this technique, the paper will describe a recent application of AGF carried out in Rome to underpass an existing metro station.INTRODUCTIONNatural ground freezing occurs seasonally or permanently (permafrost) in some areas of the globe close to the poles and can negatively affect the engineering performance of underground structures. On the other hand, Artificial Ground Freezing (AGF) is man-made controllable freezing process that can be used in foundation engineering to temporarily strengthen the ground and create a barrier to the passage of groundwater. During the process, the heat is extracted from the soil in a cylindrical shape around a number of freezing pipes installed into the ground. This action produces columns of frozen soil, which expand gradually till they merge and create continuous frozen wall. The thickness of this barrier can be regulated according to the specific project requirements. Nowadays, AGF technique is applied to a wide range of foundation engineering problems where soil stability and groundwater flows are an issue (Pimentel et al. 2011, Haß and Schäfers, 2013). Typical applications include the temporary stabilization and waterproof of the ground around the excavation profile of mined tunnels until the construction of the final lining (Figure 1).The case history described in this paper deals with a recent application of AGF carried out during the construction of metro Line “C” in Rome. Specifically, this technique has been applied to allow the construction of two single-track mined tunnels running underneath an existing metro station belonging to Line “A”. In that case, the AGF has been evaluated by the Designers as the only possible solution for improving the mechanical and hydraulic characteristics"

Jan 1, 1900

By Clifford Taylor, Alexander Zöhrer

"The execution of deep basement excavations under narrow conditions is one of the most challenging tasks in geotechnics. The vicinity of neighbouring buildings, roads, and underground structures such as sewers or power lines, quite often prohibits the application of standard solutions. In addition, legal considerations in the use of adjacent properties is becoming increasingly difficult. This paper will present some innovative approaches to overcome the above-mentioned challenges based on several case studies from central Europe. For every project the design approach as well as the techniques used for execution will be explained, detailing both the advantages and the limitations of the applications. One case study shows a deep basement excavation (approx. 17m) in the centre of Prague, Czech Republic. This project featured many challenging boundary conditions (narrow construction area, high ground water table, jet grouting column embedment into bedrock, constraints regarding use of ground anchors due to property rights, etc). The realisation of the complex design is described and illustrated in detail. Other case studies will show the combined application of bored piles with jet grouting and also explain the design of vertical prestressed anchors for retaining walls.INTRODUCTIONThe development of urban areas has always presented challenges, from access for equipment and materials to the rectification of existing foundations in unknown condition. Compounding these is the increasingly stringent requirements to retain, maintain and reduce impact on culturally and historically significant structures. As available space is becoming more limited, optimisation of real estate has resulted in buildings getting higher and their basements deeper below ground. Two or more basement levels are quite common, with typical excavation depths ranging from 5 to more than 10m. Additionally, we are faced with neighbouring buildings that are equally high, deep and massive. These buildings directly adjacent the retaining structure require underpinning to limit settlement, and in cases where they are within just a few meters, this building mass generates additional earth pressure for the retaining wall to support, resulting in complex loading cases.This paper highlights several common challenges and explores the measures implemented to overcome them. The challenges and examples of either design based solutions or practical applications will focus on the following topics – the limitations of conventional geotechnical construction methods, overcoming challenging geology and the requirement for watertight basement constructions."

Jan 1, 1900

By Stephen Buttling, Zhong Rui

"A single unit gas fired power station was being built on the edge of the Gulf of Thailand in 2001. The soil conditions consisted of very soft to soft Holocene Marine Clay, and the site was part of a coast line which had been subsiding below high water mark for some time. In order to provide access around the power station a road system in a figure-of-eight formation was required, and this also needed to be above the design flood level, allowing for future settlement. A ground improvement scheme was proposed and constructed, which consisted of two spacings of prefabricated vertical drains (PVD) over two depth ranges, vacuum consolidation and pre-loading, and rigid inclusions.During the construction phase, the vacuum consolidation was applied for 202 to 221 days in different zones, and monitoring allowed a prediction that the future settlement, including secondary consolidation over a period of 25 years, would be within the range of 175 to 355 mm, which met the contract requirement of less than 400 mm.The power plant was completed and became operational in 2003. Monitoring of the road levels continued, as did the settlement, and in early 2010 the total settlement since the end of vacuum consolidation had reached about 800 mm. The monitoring data both during the ground treatment and for the following 7 years is presented and analysed. This is supported by numerical analysis using 3D finite element methods which shows good agreement with the measured data, and allows a preliminary explanation as to why the predictions were so far out.BACKGROUNDAfter a period of bidding and negotiation, the Eastern Power and Electric Co Ltd (EPEC), an Independent Power Producer, entered into an agreement with the Electricity Generating Authority of Thailand (EGAT) in November 1997 to sell them power. In 1999 an Engineering, Procurement and Construction (EPC) contract and an Operation and Maintenance contract were signed with a supplier to provide a gas-fired (with oil as a back-up fuel) 350 MW combined cycle power plant in Bang Bo, Samut Prakarn Province, east of Bangkok. The site of the plant at Bang Bo is located immediately to the east of the Samut Prakarn Wastewater Treatment Plant, adjacent to the Gulf of Thailand (see Figure 1) in an area of very soft to soft marine clay (Bangkok clay) having low shear strength and potential for excessive settlement. The site layout comprises the main Power Plant components of generating block, cooling towers, fuel unloading area and storage tanks, switchyard and administration block, separated by access roads."

Jan 1, 1900

By Serhat Baycan, Mikias Yohannes

"Kuala Lumpur Karst is a complex limestone formation that is characterized by presence of cavities, solution channels, pinnacles and floaters. Basement excavations in such geological formations are usually challenging, mainly owing to the unpredictable rock head depths and potential for groundwater inflow. Any excavation support system should have adequate robustness and water tightness. Traditionally, Secant Bored Pile walls (SBP) with struts are the preferred option for karst ground. This paper discusses a cost effective and innovative alternative solution for a particular site – using Deep Soil Mixing (DSM) and using Contiguous Bored Piles (CBP) together with Ground Anchors (GA). The site, located around one of the busiest areas of Kuala Lumpur, is a 5,700 m2 commercial and residential development. A 16.0 m deep excavation was needed for four levels of basement and excavation support along the 275 m perimeter of the development. Within the site, the depth to rock head varied from 6 m to 19 m. The basis for each solution and conditions for its suitability are discussed in detail. Some design considerations and construction challenges are also presented. The performance of the two retention systems during excavation are presented, together with comparisons versus design predictions. Suggestions for future development are also given. Advantages of this approach compared to other traditional approaches are highlighted.1. INTRODUCTIONThe geology of Kuala Lumpur is among the most complicated and geotechnically challenging formations in South East Asia. The majority of the city falls into the Kuala Lumpur Limestone formation; which is a thick, highly-weathered and cavernous limestone. This formation is pure calcitic to dolomitic in composition, having infrequent schist and phyllite interbedding (Gobbett et al., 1973).The KL limestone has a highly karstic topography dotted with cavities, ravines, interconnected subterranean channels, pinnacles, overhangs, floaters and slump zones (Tan, 2006). This results in erratic bedrock profiles even within short distances. It is not uncommon to see a precipitous rock head incidence within short distances in the same site. In most parts of the City, the bedrock is typically encountered ranging from very shallow depths to about 30.0 m. The exception to this is at the heart of the City, where Kenny Hill formation prevails above the KL limestone. In such cases the limestone bedrock can be encountered much deeper. The erratic rock head profile and the highly karstic nature of the KL limestone makes it a geotechnical challenge requiring careful consideration of suitable engineering solutions.1.1 – Site DescriptionThe site, located in downtown Kuala Lumpur, is abutted by a busy street on the North. Before development, the site previously served as a car park. To the west an access road separates the site from an empty lot; while on the east, the lot is bounded by light weight residential and commercial buildings. On the south side, the site is bordered by a road that separates it from a prominent Shopping Mall in the City. A layout plan and an artist’s impression of the finished development is shown in Figure 1."

Jan 1, 1900

By Jim Slatter, Ben Collingwood

"It is well known that the adoption of an appropriate construction methodology is critical to quality outcomes for bored piles (drilled shafts). Many case studies have been published documenting quality issues that have arisen due to a range of causes involving ground conditions, ground support, drilling and cleaning techniques, groundwater, concrete properties and concreting methods, amongst other things. Despite the body of published information, pile defects remain common in practice. The authors share over 40 years’ experience in the Australian piling industry and have participated in many hundreds of projects involving bored piles in design, construction and testing roles. It is the authors’ experience that many defects are caused by conditions or practices that are known to be problematic, but that are often not recognised or addressed at the time of the works. This paper provides an overview of industry practices and key factors relevant to quality outcomes. The authors draw upon their own construction experience, published case studies and guidelines, and observations from independent pile testing activities they have been involved in across the Australian piling industry. The intent of the paper is to provide a consolidated review of typical industry practices and to highlight key areas in which construction quality can be enhanced.INTRODUCTIONThere are many published studies of cases where bored piles have been constructed and found to have concrete defects. The authors have had personal involvement in many cases where the outcomes and learnings are not publically available. The nature and cause of defects is always dependent on site and project specific factors, and therefore methodologies and materials that produce satisfactory outcomes in certain circumstances may be problematic elsewhere. The process of bored pile construction encompasses the following key areas:??excavation and ground support;??pile preparation and cleaning;??pile reinforcement and fitments.??concrete supply and mix performance;??concrete placement methodology;Each of these elements is equally important and can influence construction quality in completed piles. In the authors’ experience, it is often a combination of seemingly minor issues that leads to significant defects in piles. Conversely, attention to detail in all aspects of bored pile construction is required to produce outcomes of a consistently high standard."

Jan 1, 1900

By Stefano Pirrello

"Sydney’s booming real estate market has pushed property developers to invest in historically “no-go” areas, which were previously too expensive to develop. These areas are usually near rivers where the sites are underlain by deep alluvial and estuarine sediments. In these ground conditions conventional bored pile techniques are often not competitive. Contiguous Flight Auger (CFA) and Drilled Displacement Piles (DD) techniques are on the other hand suitable for these ground conditions. This paper deals with the design and construction challenges encountered with these piling techniques for a series of high-rise towers in Sydney’s West. The advantages of DD over CFA piles such as reduced overall spoil with substantial cost savings and achievable rock sockets in medium strength bedrock are discussed. Design validation through interpretation of real-time data from the piling rigs’ on-board computer data, and low and high strain pile dynamic testing (PDA) is discussed. Testing data is presented as CAPWAP (Case Pile Wave Analysis Program) analyses for different concrete grades.INTRODUCTIONThe booming real estate market in Sydney has pushed property developers in investing in historically “no-go” areas, which were previously too expensive to develop. These areas are usually near rivers where the sites are underlain by deep alluvial and estuarine sediments. In these ground conditions conventional bored pile techniques are often not competitive. Contiguous Flight Auger (CFA) and Drilled Displacement (DD) Pile techniques are on the other hand suitable for these ground conditions and were utilised using concrete injection methods. This paper deals with the design and construction challenges encountered with these piling techniques for a series of high-rise towers in Sydney’s West.GEOLOGY & GEOTECHNICAL CHARACTERIZATION OF THE SITEThe Sydney 1:100 000 Geological Series Sheet shows that the site is underlain by man-placed filling and alluvial/estuarine sediment. The sediment comprises silty to peaty sand, silt and clay. Shell layers are also expected to be present within the soil profile. The Prospect/Parramatta River 1:2500 Acid Sulphate Soil Risk Map shows the site as ‘Disturbed Terrain’ in which soil investigations are required to assess acid sulphate soil potential. Several Cone Penetration Tests and Boreholes were carried out during the geotechnical investigation. All boreholes were extended to bedrock and NMLC-sized diamond core drilling was used to obtain 50mm continuous core of the rock, enabling unconfined compression strength testing to be carried out on selected samples. A summary of the ground conditions encountered on this site and inferred from the CPTs can be described as follows:"

Jan 1, 1900

By Cheng Lin, Guoming Lin

"This paper presents a case history for the design, construction and long-term performance monitoring of a driven prestressed concrete (PSC) piled foundation supporting a large liquefied natural gas (LNG) tank in Savannah, Georgia, USA. Following a geotechnical investigation, a design stage pile test program was performed with three objectives: to study the densification effect from pile driving on the liquefaction resistance, to test axial and lateral pile capacities, and pile behavior under lateral loads. The test program comprised five piles driven on a test pad constructed adjacent to the tank foundation. Cone penetration testing (CPT) was performed before and after pile installation to test soil densification effects from the pile driving and liquefaction potential was re-evaluated based on the soil densities after pile installation. The axial load tests involved static load testing, high strain dynamic testing, and Statnamic testing. This paper presents the findings of the densification effects, compares results from different axial testing methods and discusses the procedures to use the load test results in the pile design. The paper also comments on the construction issues and presents performance data with 10 years of monitoring.1. IntroductionThe project site is located at the Kinder Morgan’s Elba Island LNG Terminal on the Savannah River which is three miles downstream of the downtown Savannah, Georgia. This LNG terminal was initially developed in the 1970s as an LNG import terminal. The facility includes five LNG storage tanks with two larger tanks which were constructed in 2003 and 2006, respectively. The terminal is currently being converted into a liquefaction and export facility. This paper discusses pile foundations for Tank D4 which is a double walled insulated steel tank built to hold one million barrels of LNG in 2003. This tank has an outer tank diameter of 258 feet, an inner diameter of 252 feet, and liquid height of 113 feet. A number of geotechnical challenges were present in the foundation design and construction.??The site is a typical coastal deposit site featuring a thick layer of very soft under-consolidated clay (up to 40 feet in thickness);??The bedrock is a couple of thousand feet deep;??There is a sand layer that is liquefiable under a high seismic design category (0.5% possibility of exceedance in 50 years)."

Jan 1, 1900

By Lucie Spencer, Craig Butterworth

"This paper presents the design of a raft enhanced pile group recently constructed for a hotel development in Perth, WA. At the time of construction in 2016 the hotel was the tallest prefabricated hotel in Australia.The structure covers the entire 12 m by 32 m development footprint, located in an inner city environment, and directly surrounded by existing structures. The small site and lack of space required innovative thinking in terms of the substructure design.The ground conditions comprise a layer of medium dense sand underlain by variable layers of stiff clay, silts and sands. Groundwater was around 1.5 m below ground level.The substructure design was carried out on the basis of a raft enhanced pile group. This allowed the use of much shorter piles than a conventional pile solution, thereby permitting the adoption of CFA piling techniques. This also allowed the raft thickness to be reduced to such that the substructure works were maintained above the groundwater level.The design was carried out in general accordance with the Australian Standard AS 2159 and using conventional piled raft design techniques involving iteration between elastic soil settlement software and structural analysis software until spring reactions were obtained with convergence of the two models. Following this springs were introduced to model piles in the structure.Due to the variable nature of the ground and resulting uncertainty in pile base capacity it was not considered appropriate to design the system as a pile assisted raft with piles loaded beyond their ultimate geotechnical design strength. As a result, all piles were designed based on a maximum load maintained within the elastic response region, with the majority of the load taken by the piles. However, the combined capacity of the raft and the piles allowed for a saving in pile lengths and numbers of around 40%, when compared to a conventional pile group designed in accordance with the Australian Standard AS 2159.The raft slab was monitored during construction in order to check the actual displacements against the design displacements. At the end of construction, the settlements were found to be within 2 mm of the design values.INTRODUCTIONThe Wellington Street area of Perth in the CBD is undergoing recent regeneration which includes the King’s Square development, Perth Arena and the Wellington Street Bus Station. The proposed hotel development is close to the recent developments on a Lot previously occupied by a low rise development. Due to the small size and constrained nature of the site, the substructure design for the tower needed to take into account available space and the impact of the works on adjacent properties. This paper presents reasoning for the choice of substructure design, details of the design methodology adopted, results from limited post construction monitoring and potential improvements that could be considered for similar future developments."

Jan 1, 1900

By Nasr Sheta

"After Hurricane Sandy, the stability of an earth slope in the Atlantic Highlands, New Jersey in the United States was deteriorating due to slumping soils and erosion from flooding. A slope stability evaluation indicated the slope did not satisfy the requirements of the local building code. A triple-tier, pile-supported and mechanically stabilized earth wall was designed and constructed to stabilize the slope. The construction was planned from a 3-m-wide roadway and, because of rough terrain and limited work space at the site, a cast-in-place drilled-pile construction was deemed impractical due to slow pile production. An alternative procedure was utilized by pre-drilling holes, and installing precast tip-and-shaft-grouted (PCTSG) piles, which extended to competent soils to improve slope stability. A grade beam, connecting the PCTSG piles along with soldier beams and concrete lagging were used to form the lowest tier of the slope stabilization, while the middle and higher tiers were built as mechanically stabilized earth. The stability of the proposed stabilization was analyzed using 2-D non-linear finite elements. After construction, monitoring of the wall continued for about 8 months to check its performance, and indicated lateral and vertical wall movements were less than 25 mm and 6 mm, respectively, indicating effective slope stabilization.INTRODUCTIONStabilizing earth slopes using piles to connect near-surface unstable soils to underlying stable ground masses has been investigated by many researchers, who presented various approaches to evaluate the contribution of the pile system towards improving the stability of the slope. Some of these approaches consider the piles as structural elements receiving forces from the upper sliding ground mass and transmitting these forces to the underlying stable one. The force from the top sliding mass is applied at between one third and one half of the pile embedment into the top sliding mass, Anagnostopoulos et al. (1990), Fukuoka (1977) and Matsui et al. (1988). The point of application of the sliding force was explored based on successful case histories while addressing the safety factors for both geotechnical and structural design, Vessely A. et al. (2007). The development of numerical analysis techniques utilizing the method of finite elements (FE) also enabled better analysis and design of slopes stabilized using piles. A FE-based approach was successfully utilized to design slope stabilization with target safety factor based on the shear and bending demands and the spacing of the piles, Pradel D. et al. (2010).After Hurricane Sandy in October 2012, the stability of many properties constructed atop earth slopes located along the coast of the Atlantic Ocean has become a concern due to storm-induced erosion. This paper presents the analysis, design and construction of a hybrid slope stabilization system utilized at one of these storm-impacted properties, which is located in the Atlantic Highlands, New Jersey in the United States. The subject property consisted of a two-story residential dwelling and a parking structure, and was built on top of an about 8-m-high earth slope having crest at about elevation 10 m (el 10) and toe at about el 2."

Jan 1, 1900

By J. Racinais, P. Vincent

"In September 2011, Menard Oceania (MO) was engaged by Mac Mahon John Holland Joint Venture (MJHJV) to provide ground improvement solution for the $34bn Ichthys LNG development. With close to 400,000m2 of mangrove swampland set to be reclaimed and improved, this project was a great opportunity to showcase the technical, commercial and environmental benefits that Dynamic Replacement (DR) ground Improvement technique can provide. The ground improvement works involved complete design and construction for the Ichthys LNG site located at Blaydin Point on a low lying peninsula in Darwin Harbour. Dynamic replacement and stone columns technique were selected to treat intertidal mangrove mud to achieve required bearing strength, stability and limit settlement to an acceptable levels. The site is underlain by a 3m to 5m thick layer of highly organic mangrove muds with very soft shear strength ranging from 0kPa to 12kPa at depth. The site is exposed to daily sea water level tidal variations of up to 8m, which created significant constructability constraints and slope instability risks. This paper presents the design philosophy, the process involved in the selection of the construction methods, the site constraints encountered during the works and a review of the results achieved, quality control and post constructions performance.INTRODUCTIONInpex Browse, Ltd (Inpex) and its partner Total are developing the Ichthys gas field to pipe gas to onshore facilities at Blaydin Point on the south side of East Arm in Darwin Harbour. The proposed LNG plant consists of gas receiving facilities, 2 x 4.2Mtpa nominal capacity LNG trains, LPG and condensate production facilities, product storage and export facilities, a module offload facility (MOF), a flare pad (FP) and associated off plot facilities.The proposed on-shore facilities are located on extremely soft intertidal mangrove muds, therefore an appropriate ground improvement was required to achieve required strength and stability of site works and limit long term settlement to an acceptable level.Various ground improvement techniques were studied to select the most suitable for the ground conditions and site constraints encountered at the Blaydin point site. Dynamic replacement technique was selected for onshore section to improve soft mangrove mud to depths of 5.5m and Stone Columns (SC) technique was selected for MOF off-shore section to improve intertidal deposits to a depth of 2.5m.This paper presents DR design and construction works performed between December 2012 and August 2013 at Flare Pad Area."

Jan 1, 1900

Jan 1, 1900