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By Brian Littlechild

Whilst there is much innovative work being undertaken in South East Asia in the space allowed in this paper we have settled on describing in more detail the work that has been done with shaft grouting of deep foundations and piles founded in rock both in end bearing and socket friction. The paper is necessarily in two parts. The first part is about the application of shaft grouting since its introduction to the region some eight years ago. It describes, for the first time, much of the detail of the different techniques used and the construction and the design benefits achieved with shaft grouting in five countries in the region. The second part outlines the enhancements achieved in the design of piles founded in rock and brings together the results of 10 years of test loading. This includes the load testing of 1.2m to 1.5m diameter piles to a maximum of 30MN on granite and a recent programme of tests on a wide range of strong rock types in Hong Kong. The ground conditions for these deep foundations vary widely, from sedimentary soils to in situ weathered granite and meta-sedimentary rocks. The construction techniques include barrettes constructed using mill techniques and bored piles formed under bentonite and water using both oscillators and rotators.

Jan 1, 2000

By Peter Deming

"PART 2 OF 2 (CONTINUED FROM SUMMER 2006 EDITION) CONSTRUCTION ISSUES (cont’d) The Influence of Ground Conditions on Collapse Sand and gravel strata provide frictional resistance to support active earth pressure. The angle of internal friction has only slight influence on computed stability. Sand and gravel material design parameters can be defined with SPT N-values. Silt strata should be analyzed using internal friction. Definition of soil parameters should be performed by laboratory testing. Cohesive materials, especially soft clay and peat, require careful definition for design. Shear strength should be determined by laboratory testing. Work platforms constructed over granular strata improve the ground resistance by increasing confining pressure. However, temporarily increasing overburden stress on cohesive ground reduces trench stability. If the ground contains soft cohesive deposits which are not normally consolidated to the construction overburden, these must be stabilized before attempting trench construction. Use of wick drains and surcharge fill to improve the ground is recommended. Ground stabilization work requires time, and should be performed by the Owner prior to trench excavation. The addition of cement, stone columns, or other measures to support trench excavation equipment is typically determined to be more expensive and less dependable than ground improvement. Excavation through peat can be especially problematic. Peat materials rapidly compress when earth pressures exceed preconsolidation stresses. Backfill materials provide a horizontal stress on the trench wall which can exceed the bearing capacity of peat. As the peat compresses, the trench becomes wider, and slurry levels drop and trench stability can rapidly deteriorate. If the peat is the closure layer, a shallow key is recommended. If peat is present on the trench wall, preconsolidation with surcharge is recommended. Bottom preparation and Backfill Placement Trench wall stability is a temporary condition which must be controlled by proper design and construction of work platforms and slurry features which influence ground support. Backfill materials and intimate contact of the backfill with the closure layer are permanent conditions which are the end goal of the work. The most common reason slurry trenches fail to provide working barriers is improper bottom closure. Either the closure layer is not engaged, or the backfill is not in intimate contact with the closure layer. This can result from construction problems associated with sidewall collapse described above, slurry performance and/or degradation, backfill placement methods, and failure to maintain the trench bottom clear of sediment prior to placing backfill."

Jan 1, 2006

By Roderic A. Ellman

The new Woodrow Wilson Bridge (WWB) will replace the existing bridge over the Potomac River to connect Alexandria, Virginia to Prince Georges County, Maryland. The new WWB will extend approximately 1.1 miles across the river, with a 367-ft long bascule span in the main river channel where the water depth is about 36 ft. The subsurface soil profile consists of up to 50 ft of a soft organic silty clay layer that is very vulnerable to scour, underlain by a deep deposit of hard sandy clay. Foundation construction in the Potomac River required the use of cofferdams to allow structural concrete work to be performed in the dry. This paper will the present the types of cofferdams used to construct the foundations for the WWB replacement project. The bridge is primarily comprised of fixed spans in relatively shallow water and a bascule span over a navigation channel in relatively deep water. Foundation construction included the installation of 48" to 72" open end steel pipe piles and cast-in-place concrete pile caps. To achieve the desired bridge appearance, pile caps were required to extend below the water surface and below the existing river bottom in shallow water locations. Conventional steel sheet pile cofferdams with tremie concrete seal were used to construct fixed span, shallow water piers. Selection of deep water bascule span foundation cofferdams was governed by several factors including contraction scour, environmental considerations and cost. Potomac River cofferdams, i.e., relatively shallow depth cofferdams that are supported by the foundation piling were selected. This cofferdam system provided a shallow profile which minimized contraction scour and the amount of filling in the river. Design issues include load selection and cofferdam stability in very soft alluvial soils. Construction issues include erection sequence, tremie concrete mix design and placement procedures.

Jan 1, 2005

By Bora Okumusoglu, Devon K. V. Mothersille

"AnchorTest is an innovative software package, specifically developed for tablets, that permits ground anchor test data assessment and management in real time. The solution has two components: a front-end tablet app runs on the Apple iPad platform, and a back-end Cloudbased system running on Amazon Web Services with an online cross-platform website, which can be accessed from any PC, tablet or even mobile smartphone. This tool provides full data analysis and data management capabilities and portability to create greater efficiency in the anchor testing process. AnchorTest is programmed to accommodate the major international anchor testing codes and incorporates an intuitive user interface, which is revolutionary compared to conventional engineering software designs. The use of this tool creates an environment where the testing of ground anchors has effectively become a paperless exercise with greater efficiency and access to instantaneous feedback on the performance of anchors in relation to established acceptance criteria.Historically, project personnel record and analyze the results from anchor load tests using spreadsheets and a laptop computer and/or on predesigned paperbased test sheets (usually as a backup of the testing). In addition, the processing of the test results is not typically performed in real time as the testing progresses — the calculations and analysis are performed either afterward while still on site (if a field office is available) or after returning to the office. Undoubtedly, on larger projects containing numerous anchors where multiple anchor tests may be performed at the same time, processing, analyzing and accepting the load test data and results can be especially time consuming, which could cause delays to the construction schedule.DevelopmentThe need for a more automated and digitized approach to record, process and analyze the data from anchor load tests was highlighted at a deep basement project for a mixed-use development complex in Moscow, Russia. The diaphragm wall supporting the structure was approximately 1,970 ft (600 m) in perimeter length and about 148 ft (45 m) deep, with an excavated depth of about 82 ft (25 m), which required six levels of single bore multiple anchors (SBMAs). This project provided a challenge to recording, processing and signing off on the data generated from some 3,600 3-unit SBMAs. More specifically, for this project, three hydraulically synchronized stressing jacks were used to stress and proof test each 3-unit SBMA, which resulted in nearly 10,800 data plots of the load-extension tests being generated. This project served as the main impetus in the conceptual design and optimization of AnchorTest."

Jan 1, 2017

By Nabil F. Ismael

Load tests were carried out to examine the ultimate bearing capacity of short, large diameter bored piles in connection with the construction of a multistory building on the Arabian Gulf in Kuwait. Testing included 0.45 m, 1.0 m, and 1.2 m piles installed through loose sand into a bearing stratum consisting of very dense cemented sands. All tests were carried out to failure. The base resistance and shaft friction were calculated using the Meyerhof method for a layered soil profile. The method employs the standard penetration test N-values. The results indicate that the piles are end bearing piles with a great portion of the pile capacity due to base resistance. The mobilized skin friction is small. The calculated pile capacities were very close to the measured values with the maximum difference not exceeding 10%.

By R. A. Fraser

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

Jan 1, 2010

By Ben C. Gerwick

This publication is intended to document recent innovations and technologies that have the best potential for effectively improving the quality of marine foundations while reducing the cost, time and risk of construction. Marine foundations originated in Neolithic times with the Swiss Lake Dwellers who constructed pile-supported houses, safe from invading tribes. The Queen of Babylonia built the first recorded bridge in 1500 BC across the Tigris. The foundations were large flat stones laid on the river bottom. About the same time in India, builders extended their water well techniques to the construction of ?well? foundations in the beds of their rivers. These were really the first open caissons; brick walls were built up in a circular ring while divers excavated sand from the bottom, sometimes at a depth of 100 feet. The Romans extended the clay-filled cribs of the Middle East to shallow cofferdams, which they sealed by underwater concrete made with pozzolanic cement from Mt. Vesuvius.

Jan 1, 2013

By Jakub Szary

Excavation and shoring adjacent to the above-grade Gilmore train station and elevated guideway was undertaken in 2019. A perimeter secant pile cut-off wall was constructed to a depth 37 m (121 ft) below ground surface consisting of 1.0 m (3.3 ft) diameter drilled piles spaced 750 mm (2.5 ft) on-center, tied back with soil anchors, and reinforced with W610 steel sections every 4th pile. A bracing/jacking system was also constructed to support 3 free-standing guideway caissons within the excavation. An automated instrumentation program was installed to monitor movements of shoring walls and train infrastructure in real time and consisted of a robotic total station, inclinometers, tiltmeters, strain gauges, extensometers, and anchor load cells. Baseline monitoring was able to establish diurnal and seasonal movements within the structure, strongly correlated with temperature. The system actively monitored various shoring elements and train infrastructure in real time and alerted the project team when values exceeded predetermined threshold values. Remote reconfiguration of the automated system allowed for more frequent monitoring during jacking of Pier 29 in March 2022. Monitoring data was in agreeance with on-site manual surveying results and jacking dial gauges, and proved to be a reliable monitoring system for construction applications.

Sep 1, 2022

By Danny Déry-Chamberland, Peter Bowman, Michael Byle

"The Barrage des Quinze dam is a concrete sluice dam consisting of 19 spillway sections, each of which is approximately 7.6 metres wide and 14.5 metres deep. Rehabilitation efforts being performed on the dam including demolition and improvement of the roadway and spillway sections and grouting to mitigate underseepage. Initially, conventional cement grouting was attempted and was successful in 14 of the spillway sections, but unsuccessful in 5 of the sections due to the high water flows which washed the grout away. The removal of the roadway and portions of the piers during construction temporarily reduced the stability of the structure limiting grouting pressures that could be applied. This and the substantial high water flows (leakage) beneath the dam between the concrete/rock contact and within fractures in the upper rock formation created a challenging situation to create a cutoff.A grouting solution was developed that involved implementing several different grouting methods and materials including balanced high mobility grouts (HMG); low mobility grouts (LMG); polyurethane grouts; and sodium silicates. Because of the critical scheduling for the work, multiple approaches were planned and made available on site so that the work could proceed with the best technology with little, if any, time loss. The end goal of the grouting program was to create a seepage cutoff beneath the 5 sections of the dam in a stepwise process. The initial step was to fill the large openings and create a grout barrier to reduce the high water flow. The second step was to seal the contact between the base of the dam and the bedrock; and the third step was to complete closure by grouting a deep grout curtain into the underlying rock. Other features of the work included an extensive grout mix testing program, water pressure testing, borehole camera survey, and monitoring of the grout injections."

Jan 1, 2016

By Takeo Asanuma, Sachihiko Tokunaga, Hirofumi Taguchi, Yasuhiro Ootsuka, Yosuke Tanaka

The Cement Deep Mixing Method (CDM Method) is a ground improving method that has been used for mainly offshore sites to strengthen the soft ground below the sea bottom by injecting and adequately mixing cement slurry with soft soil into the ground to form a ground-improving column. In recent years, the CDM Method has increasingly been adopted for ground- improving work as part of liquefaction countermeasures and earthquake-resistant reinforcement in the shallow waters of river mouths and inland waters. In consequence of that, a pontoon-mounted CDM Method (CDM- FLOAT Method) has been developed for shallow waters, which is equipped with a land-type mixing machine combined with system management equipment and a tide level-based control function. This CDM-FLOAT Method can be deployed at work sites where the conventional offshore-use CDM barge cannot be employed. This report describes the CDM-FLOAT Method and the scope of applications together with construction work procedures, and a representative case of use of the CDM-FLOAT Method is introduced as an example of earthquake-resistant reinforcement of the existing embankment of a canal.

Jan 1, 2015

By K. C. Foye

Use of load and resistance factor design (LRFD) of foundations is growing, from offshore applications to bridge applications and beyond. The development of load and resistance factors for design has traditionally relied on calibration to traditional factors of safety. This technique, however, offers little insight into the challenges of pile design. This paper discusses an approach to LRFD factor development that seeks to isolate the various sources of design uncertainty. Using this approach, reliability analysis is used to develop resistance factors for the design of driven pipe piles in sand. These findings shed light on many aspects of the ongoing discussion of how LRFD can be successfully applied to pile design.

Jan 1, 2008

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 D. Dreher Whetstone, Paul M. Blakita, Christopher M. Reith, Ravi P. Malviya

"Micro-piles are small diameter (5 to 10 inches), cast-in-place piles which can develop high load capacities by bonding with soil or rock. Micro-piles are particularly well-suited for moderate to heavily loaded structures requiring deep foundations in difficult subsurface conditions, such as karst, bouldery mine spoil, or unsuitable fills with concrete debris or other obstructions. Attempts to install conventional deep foundations including driven piles, drilled piers, or auger-cast piles are likely to be fraught with construction difficulties and disputes, delays, cost overruns, and may be unfeasible in some cases. Micro-pile installation equipment is very effective in installing foundations through such overburden or rock materials.This paper presents case histories of Micro-pile installations on two projects with difficult soil/rock materials. The project sites are located in Charles Town, West Virginia and Masontown, Pennsylvania.Charles Town, West Virginia ProjectThe Charles Town project entailed construction of a four-story pre-cast concrete garage. Triad Engineering, Inc. performed a geotechnical investigation for this project (Triad, 2001). The subsurface, geologic, and project specific information described in th is paper are largely based on the aforementioned geotechnical report.Ground ConditionsThe project site is located in Jefferson County, West Virginia, and is mapped to be underlain by the Elbrook Formation. This formation is described as argillaceous, dolomitic limestone with beds of dolomite and aphanitic and algal limestone (Dean, et al. , 1990). The carbonate rocks at the site were characterized as ""moderately solution-prone, highly calcareous and weathers differentially to produce a pinnacled or ""sawtooth"" top of rock profile. (Triad, 2001 )"" Overburden soils consist of low to high plasticity, fine grained residual soils formed by weathering of the parent carbonate rock. The residual soils include variable proportion of sand and rock fragments."

Jan 1, 2005

By Frederick C. Rhyner

The United States government sponsored the construction of a new vehicular bridge over the Diyala River in Bubriz, Iraq. This paper describes the geotechnical engineering for design and construction of drilled shaft foundations for this bridge. An Iraqi geotechnical engineering firm made borings and laboratory tests while analysis and design recommendations were provided in the United States. Despite the severe challenges of engineering in a war zone, excellent cooperation was the key to a successful effort. Three drilled shafts designs were necessary to accommodate the different subsurface conditions: a) medium-compact to compact sands, b) stiff to hard clays and c) mixed soil profile. The alpha and beta methods were used to estimate capacities for a conservative design, recognizing that quality control during construction might be less than what is normally provided in the United States. Iraq has a high seismic risk and LPILE was used to estimate the drilled shaft response during earthquake loading conditions. Settlement estimates were made using FHWA methods. Construction was carried out entirely by local Iraqi firms, despite the challenges of working in an active conflict area.

Jan 1, 2009

By Toshio Yonezawa, Helmut Florian, Herbert Kuh, Masamichi Aoki, Takao Koono, Franz-Werner Gerressen

"To increase the bearing capacity of the ground, soil improvement technique is often adopted. One advantage of soil improvement techniques is the fact, that the impact to the environment is low, as the system utilizes the existing soil. Recently, compressive strength of soil improvement gets more into the focus for the use of building foundation. To prevent brittle fracture, which is a weak point of soil improvement, fiber reinforced soil improvement has been developed. Laboratory tests were conducted to examine the fibers suitable for reinforced soil improvement, and examine the optimum mix design for fiber cement slurry. Based on the laboratory tests, polypropylene fiber and cellulosic viscosity admixture was selected. For the laboratory tests a scaled model of CSM mixing head was used to examine the dispersion of the fibers in the ground. Using the CSM mixing head, the outer periphery fibers of soil improvement seemed to be arranged in the vertical direction, toughness performance of the soil improvement could be improved. Furthermore, full scale field test was performed using actual CSM unit, modified to enable the use of fiber mixed slurry. The validity of the material as well as the toughness performance of the soil improvement, determined from lab test results, was confirmed. In addition, it was confirmed that fiber reinforced soil improvement can be constructed appropriately by CSM method.2 INTRODUCTIONSoil improvement technique to improve the strength and deformation performance of ground has been used for a long time. Cement improved methods, with the increase of the deep Mixing Method, which has been disseminated since the 1970's, was often used since. Cement used soil improvement technology has been utilized to stabilize excavations, slopes in embankment and much more. Recently, it can be used for preventing liquefaction by building soil improvement in a grid (Suzuki et al. (1996)), and also as basis of the structure by increasing the compression strength of soil improvement (Yamashita et al. (2011)). Cement used soil improvement method, a technique for mixing the in-site soil and cement, can effectively utilize natural resources, and it can be expected that its use will increase further in the future. Therefore, soil improvement technique will be able to minimize the impact on the environment. Cement improved soil is a mixture of soil particles and cement with high compressive strength but low tensile strength. Since tensile strength of soil improvement is low, brittle destruction occurs. Therefore, it is not possible to use soil improvement in conditions acting with bending stress. If a horizontal impact force occurs in the improved soil, the width of the soil improvement needs to be increased to reduce the bending stress. If preventing the brittle fracture of soil improvement, the width of soil improvement could be reduced, then less resources would be needed. In order to increase the tensile strength of the soil improvement, several studies for the mix of fiber and soil were performed. Victor (1992) indicates cracking deterrent effect by fiber based on laboratory tests. Moreover, based on laboratory tests, Hayasaki (1982) illustrated the effect on the tensile strength of the fiber types, the type of fiber, the diameter of and the length of fiber."

Jan 1, 2015

By Douglas G. Baker, Jason K. Braund-Read, Megan R. Sheffer

"Mica Dam, owned by British Columbia Hydro, is an 820 ft high earthfill embankment dam that was completed in 1973. The dam consists of a thin central impervious till core supported by upstream and downstream compacted sand, gravel and cobble shell zones, founded on bedrock and valley bottom alluvium deposits. In 2012, a project was started to install new piezometric instrumentation within the dam’s foundation and downstream shell zone.Deep drilling in large embankment dams is very difficult and requires careful planning to select a methodology capable of reaching the target locations, while ensuring that no damage is done to the surrounding dam fill zones. At Mica Dam, the drilling could only be carried out from the Dam Crest and drillholes had to be carefully oriented to avoid intersecting any existing dam instrumentation. The drilling work therefore required angled drillholes, at depths of up to 855 ft, through heavily compacted sands, gravels and cobbles, and to significant depths below the standing water table.During the planning stages for the Project, in early 2013, the preferred drilling method was selected and a drilling contractor was engaged for the drilling work. Critical dam safety concerns were identified and addressed during the design stage of the Project with the drilling contractor, so that risk mitigation measures and response plans could be effectively developed.This paper explains how background information and prior drilling experience influenced the final design and implementation of the drilling techniques used in 2013 to successfully drill the deep holes and carry out the piezometer installations in Mica Dam. Drilling procedures, instrumentation design and installation methods, as well as risk mitigation measures, are discussed."

Jan 1, 2017

By Daiki Takano, Naoki Takahashi, Hidenori Takahashi, Ikuo Towhata, Yoshiyuki Morikawa

"The method in this study, in which cement-treated piles are installed into the ground to decrease the amount of liquefied lateral flow, has been studied. The authors are also investigating the most effective arrangement of piles to optimize cost-effectiveness. In their investigation, they propose shifting the position of the piles to prevent lateral flow in various directions. The present study conducted centrifuge model tests to clarify the improvement effect of piles against the lateral flow of liquefied soil and the effect of the pile arrangement. Then, numerical fluid analyses were conducted to consider the improvement mechanism. As a result, the model tests and numerical analyses showed that the pile improvement dramatically reduced the lateral displacement and that the average total flow velocity decreased in the irregular case.INTRODUCTIONLiquefied ground subjected to seismic motion loses its stiffness and strength, and lateral flow often occurs in sloping areas and backfill areas behind collapsed quay walls. In the Hyogoken–Nanbu Earthquake in 1995, the reclaimed island that was surrounded by collapsed quay walls expanded toward the sea and the amount of displacement reached a few metres (Hamada et al., 1996). Two countermeasures can be considered to guard against lateral flow: preventing liquefaction and reducing lateral displacement. The former method is ideal; however it is costly and time-consuming. Based on these considerations, the authors (Takahashi et al., 2013; Morikawa et al., 2014) are currently studying a method in which cement-treated piles are installed into the ground (see Fig. 1) to decrease the amount of liquefied lateral flow. The countermeasure cost using this method is relatively low because of the low replacement ratio. The authors are also investigating the most effective arrangement of piles to optimize cost-effectiveness. It has been proposed that the position of the piles should be shifted so that lateral flow can be prevented in various directions, as described in Fig. 2."

Jan 1, 2015

By Joseph T. Coe, Siavash Mahvelati, Philip Asabere

Characterization of existing foundations remains an important issue as foundation reuse and rehabilitation continue to garner increased attention. In the case of unknown foundations, geophysical and nondestructive testing (NDT) methods have been utilized in the past to evaluate foundation geometry and could serve as useful tools in the case of foundation reuse. A comprehensive study was initiated in the late 1990’s and early 2000’s that evaluated the effectiveness of the available geophysical and NDT technologies to characterize unknown foundations for scour evaluation purposes. At the time of that study, the Multichannel Analysis of Surface Waves (MASW) geophysical method was in its infancy and not widely used. Since then, MASW has become increasingly prevalent in geotechnical applications as the method presents a number of potential advantages when characterizing the subsurface, including rapid testing, increased signal to noise ratio, and ability to resolve velocity inversions. This paper presents a case study that explores the abilities of MASW as an unknown foundation characterization tool. MASW was applied to determine subsurface stiffness at a bridge foundation site in the Philadelphia metropolitan area. One MASW survey line was performed immediately over the foundation of interest and another was performed over a control zone adjacent to the foundation to establish a baseline site profile. The purpose of this testing was to examine whether MASW could establish the geometry of the foundation at this site. This paper presents the site conditions and MASW testing procedures, followed by a discussion of data analysis and interpretation.

Jan 1, 2016

By Racquel Nottingham, Marc Mastrantuono

Micropiles often provide a favourable solution for many deep foundation problems especially when significant site constraints such as confined construction sites or vibration limitations have been identified. Often the durability of buried steel elements are heavily scrutinized in order to effectively determine the rates of corrosion and methods to reduce this while still maintaining the structural integrity of the engineered solution. Practices such as sacrificial corrosion loss and the introduction of plastic sheaths have become the go-to methods of corrosion protection. Since the introduction of the micropile, other solutions have been developed, namely protection with an adequate grout encapsulation. This paper will explore corrosion protection of micropiles and the guidelines provided in the published codes and norms. Since few codes define the exact way to verify the durability of these micropiled structures, the existing data is presented and the analysis of grout encapsulation as an effective corrosion protection method is evaluated.

Oct 1, 2022

By Cen Guoji

The foundation of bored pouring concrete pile have been adopted in the bridge engineering of China since early in the sixties. They demonstrated tremendous technical advantage and achieved notable economic benefit. With improvement of bridge technique including construction technique work equipment, design theory, examination in quality and applicable range etc, the pile diameter became bigger and the foundation changed from shallow to deep-water. This paper examples Jiujiang Bridge of Guangdong in China, which is single-tower cable-staged bridge, total length of 1675m, and expouds adopted successfully the foundation of variable section large bored pile (upper part d=3m, central part d=2. 4m and lower part d=2m) on the conditions of complicated technique that the load is tremendous (it require specially to resist 12000 kN ship impact) and the piles have free length 30m. The paper will be to describle design project and construction practice of pile foundation with variable section, and to compare schemes of equal section pile and pile in sinking-well.

Jan 1, 1991