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By Ivan Jackson Madura

The new Paradisus Coco Beach Resort in Rio Grande (PR) is located on an old swamp area, which has been filled with relatively clean to silty sands. The swampy deposits consists of organic silts, peat and loose fine to medium sand and silty sand. The project requires the placement of 1.0 to 1.5 meters of additional fill together with the construction of light structures. The need for the fill will trigger the development of settlements in the underlaying weak and compressible stratum. Furthermore, the susceptibility of the loose sand to liquefaction during an earthquake was considered. This paper describes the soil improvement by means of vibro-replacement, the purpose of which was threefold: reduction in total and differential settlement, acceleration of settlements during the surcharge period and densification of the loose sand to reduce its liquefaction potential. The predesign is presented together with relevant construction details of the preliminary trial areas from which the final column diameter and grid spacing were derived. Instrumentation together with settlement observations during the surcharge period are presented as well and compared with the initial predictions.

Jan 1, 2002

By Guan Jichang

An abandened breakwater, located at the rear of No. 2 berth in Dongdu Port area of Xiamen City, was not cleaned thoroughly when the backfilling of sand started. The uncleaned stone layer was about 2 to 3 meters deep, with the average piece of stone weighing about 1 to 3 kN. A large grain storing house, 220X 60m2 in area, was designed and built at the above mentioned complicated site. The foundation of the grain house are made up of the cast-in-situ piles. It is well known that it is difficult for the submarine engineering drill to go down through such large-sized stones. Having com-pared the various plans, a final decision has been made which involves explosions with small amounts of charge plus cone bit in the enlarging of the size of the pores. Such a method has successfully prevented the pores from slumping and made it possible to fulfill the project without any difficulties. This paper also introduces the ways in effectively dealing with each individual stone.

Jan 1, 1991

By Jom Gentry

Acrylamide chemical grout (C3H2NO) has been successfully used for over 50 years to control groundwater and stop infiltration. This paper will address three unique projects involving the control of groundwater with each study providing special circumstances and geological conditions: encapsulation of radioactive hazardous waste in the United States, a tailings dam for a large copper/gold mine in Argentina and 27 miles of leaking subway in Canada. The primary reasons for selecting acrylamide grout were based on the following characteristics: thinnest chemical grout on the market, a true solution grout which contains no suspended solids in the blended product, flexible gel set times, and a 362 year half-life in soil as determined by the U.S. Department of Energy.

By F. H. Chen

the Rocky Mountain Region since 1950, drilled pier foundations have been widely used to combat structural movement problems in expansive soils. It is now an accepted practice for engineers to use drilled pier foundations in expansive soil areas. Piers are generally drilled into bedrock in a zone unaffected by moisture change. With some exceptions, such system has successfully prevented damage incurred in the structures as the result of soil expansion. In the last 15 years, no significant advancement has taken place in the design of the drilled pier system on expansive soils. Numerous failures continued to be reported. Causes for the failures were placed on poor drainage, inadequate void under the grade beams or mushrooms on top of the piers. Engineers realize that these are certainly not the major problems. The basic design criteria should be critically reviewed. It is the purpose of this paper to point out the actual problems confronted by designers, the failure module and remedial measures, The writer does not claim to have the solutions. In fact, it will be a long time before real solutions can be found, yet the writer believes the engineering communities, the construction industry and the general public should be aware of the true picture of the problem.

Jan 1, 2010

By Victor Li, Joley Lam

"INTRODUCTIONJacked piles are piles that are pressed into the ground, usually by hydraulic jacks. For this reason, jacked piles are also known as pressed in piles. Jacked piles are mainly used for the following applications.• Underpinning worksJacked piles have been commonly used for strengthening the foundation of existing structures. In pressing the pile into the ground, the hydraulic jacks will jack against existing pile caps or ground beams that support the structure or against a steel frame connected to the floor slabs or structural walls of the structure. The self weight of the structure provides the reaction force for pile jacking. Jacked piles used for underpinning works usually have lower design ultimate capacities, typically less than 2000 kN (225 tons).• New foundationsJacked piles can be used to support new structures. A heavy pile jacking machine is employed to provide the reaction force for jacking the piles into the ground.• Retaining structuresJacked piles can be installed at close spacings to form a retaining wall. For relatively large and easily accessible sites, the piles can be installed using a conventional pile jacking machine. For sites that are smaller and are more difficult to access, a more compact patented equipment called the Silent-Piler developed by Giken Seisakusho Co. Ltd. in Japan can be used.Jacked piles have several distinct advantages. The vibration and noise induced during pile jacking are minimal. Jacked piles are 100 percent proof-tested to a load level equal to the maximum applied jacking force. The pile jacking machine can also be treated as mobile kentledge for static loading test. In this article, discussion will focus on jacked piles used for supporting new structures.HISTORICAL DEVELOPMENTThe People’s Republic of China (PRC) is perhaps one of the earliest countries in which jacked piles were used as new foundations. Jacked piles had been installed in the PRC since the 1960s. The capacities of jacked piling machines used in the country are usually in the range of 3000 to 6000kN (337 to 675 tons). High capacity jacking machines with a capacity of 9000 kN (1000 tons), presently used by the construction industry in Hong Kong, were also manufactured in the PRC. There are also plans to produce machines with a capacity exceeding 10000 kN (1125 tons). It was projected by Wang (1999) that jacked prestressed spun concrete piles would become one of the most popular pile types in the PRC in the 21st century."

Jan 1, 2004

By Robert Bittner

The following is a report on the development of two unique and separate cofferdam systems used in the construction of the marine foundations for the I-205 Columbia River Bridge at Portland, Oregon for the Oregon Department of Transportation. The first of these two systems utilized interlocking H-pile 100 ft long to form a cofferdam 145 ft by 58 ft in plan and 100 ft deep. The second system consisted of two immense bell shaped steel forms. The larger of the two forms was 83 ft by 66 ft in plan, 62 ft high and weighed 450 tons. This form was externally stiffened for a designed hydrostatic head of 54 ft. Both forms were designed, except for the top 14 ft, to be set and stripped in one solidly welded unit. The supporting geological formation for the bridge foundations is the Troutdale, a cemented sand and gravel. This formation is at the ground surface on the Washington Shore and slopes downward to a depth of 115 ft below normal high water at about mid-channel. In this area the Troutdale formation is covered with a layer of fine to medium sand 90 to 100 ft thick. It was the variable depth of the Troutdale which determined the two types of foundations and the corresponding to the two cofferdam systems.

Jan 1, 2013

By Andrew Higgins, Jamey Rosen

This presentation will demonstrate some recent advancements in the applications of Project Information Systems (PIMS) technology to seepage barrier walls in the context of evolving Owner Specifications. The use of geospatial technology in particular is used to track, visualize, and analyze data from a variety of sources and serve those data to contractors and owners via dashboards and as-built drawings. Data describing the geometry of construction elements (including diaphragm panels, secant piles, and jet grout columns) is of particular importance on these projects, and this presentation will include case studies in the United States of how these data are used to determine if a barrier wall is constructed as designed and if it meets the owner specifications with respect to tolerance (i.e., if each element is sufficiently close to vertical) and overlap (i.e., do adjacent elements overlap sufficiently to prevent leakage).

May 1, 2022

By Guo Qian, Du Guangyin, Deng Yongfeng, Liu Songyu, Wang Ningping

"Metakaolin (MK) can efficiently enhance the strength and the impermeability of concretes and mortars. However, it has rarely been attempted in admixtures of cement-stabilized soils until presently. As deep mixing method is wildly used in ground improvement, the strength of cemented soils (soilcrete) and the applicability of the MK should be considered. This paper focuses on the macro-strength development of cement-stabilised silty soil mixed with MK. The result shows that the addition of MK can enhance the unconfined compressive strength of the soilcrete, which attributes to a combination of the rates of OPC hydration and the MK-CH reaction. Note that the strength of soilcrete was influenced by the properties of soil, water-to-binder mass ratio (W/B) in admixtures, which needs to be reconsidered since the binder mass composes that of cement and MK totally.INTRODUCTIONCement was used in ground modification techniques, such as the jet grouting, deep mixing method (DMM) which was put into practices in Japan and Nordic countries in the middle of the 1970s, and then spread to China, South East Asia[1]. For last decades, fly ash, slag or silica fume was mixed with cement to form the new cement base stabilizing agent in the view of economy and performance improvement. The mechanical behavior of these soil-binder admixtures (nominated as “soilcrete”), was investigated. But the soilcrete modified with the metakaolin (MK) was still not investigated much and lots of further work needs to be conducted.Some laboratory experiments of the soilcretes modified with MK have been taken[2~4]. Kolovos et al. (2013) indicates that the unconfined compressive strength has a more significant improvement when W/B equals 0.4 than that when W/B equals 1.20 concerning the water-to-binder mass ratio (W/B). Sonebi et al. (2013) investigates the mechanical behaviors of cement grouting containing MK with W/B equals 0.4, and also found the effectiveness of the addition of MK. Zhang et al. (2014) performed the studies on Lianyungang marine clay improvement showed that MK obviously enhanced the quality of cemented soils.In this paper, the strength of soilcrete modified with MK is further investigated, where the unconfined compressive strength at different curing time, the content of MK and cement (w/w) in lab conditions was discussed."

Jan 1, 2015

By Tianfei Liao

Extensive site investigations revealed that abandoned shallow mine workings exist under a site planned for construction of a major new facility. Since the mine voids were susceptible to collapse, they were stabilized by grouting. After completion of the mine remediation, three types of deep foundations (micro-piles, auger-cast piles, and drilled piers) were considered for this site. Micro-piles spread the load via the bond between the pile and the bedrock. Without significant length socketed in rock, the axial load of auger-cast piles and drilled piers has to be concentrated on end bearing. Although spreading the load is preferable in this environment, economic consideration dictated the choice of drilled piers for construction.

Jan 1, 2009

By Sebastian Fischer, Rolf Katzenbach, Steffen Leppla

"The risk management in the case of liquefaction is one of the most serious and also difficult issues in geotechnical engineering because failure caused by liquefaction is always a sudden failure without ahead indication. For that reason ground improvement technologies for the prevention of liquefaction are necessary. The paper explains the responsible and effective risk management. Methods for the risk management and stabilizing the soil sustainably are described in detail.1. INTRODUCTIONDue to population growing more and more settlement area is needed, which is often including improper regions (e.g. mountain and coast regions) with raised risk of various kinds of disasters. But also in densely populated areas the risk of disasters like landslides can occur. One reason for the raising of risk in densely populated regions can be the opencast mining for raw material production. An essential element of the opencast mining is the loose deposition of the removed overburden, the so-called “overburden dump”. When an opencast mining is running out of the raw material, an opencast hollow remains in landscape. The slope areas of these hollows mostly consist of loose bedded material of the overburden dump. Due to the end of groundwater conservation these loose bedded slope areas are flooded. In consequence the slopes are in extreme danger of becoming liquefied. The result of a liquefaction in these slopes will unavoidably be a slope slide. Such a slope slide can extend up to several hundred meters into the landscape and can move several million cubic meters of material. An upsetting example for such a landslide is the slope failure in the German city of Nachterstedt on July, 18th 2009, which made necessitate remedial measures and also prevention works for the further utilisation of the region. The phenomena of liquefaction is not limited of slopes in series of opencast mining. Especially in regions with a highly appearance of earthquakes the phenomena of liquefaction is well known.2. RISK MANAGEMENTAn essential part for the stability assessment of slope systems is the investigation of sensitivity against liquefaction. In the case of given sensitivity against liquefaction there is no calculation method according to soil mechanics to determine the factor of safety against slope failure. Just for the case that sensitivity against liquefaction is not met, a comparison of the load (effect) E and the resistance R which is the traditional verification of stability against slope failure, can be calculated (Figure 1)."

Jan 1, 2015

By A. Daouadji, P. Cazes, S. Grange, L. Briançon, R. Milane

Construction in congested urban areas is often accompanied by geotechnical problems due to high loads and the impact caused by nearby buildings. For this reason, it is important to understand the behavior of the soil and the structure without forgetting the essential role of the interaction between them. Experiments, instrumentation and numerical modeling are the main methods used to study this behavior. To this end, pressure cell, strain gages, vibrating wire extensometers and optical fiber sensors are installed on the reinforcement steel of pile and raft foundations to monitor stresses and induced deformation in these elements during and after construction. A fiberglass rod extensometer is placed in the soil to help measuring the displacement due to excess loading, knowing that the pile foundations are embedded in the Rhône’s alluviums and reach the molasse, a particular and challenging soil with properties that are not yet well understood. The objective of this paper is to present the geotechnical instrumentation program carried out for the tower Silex2 in Lyon, France, and to describe the types of sensors used and their installation on site. INTRODUCTION The complexity of geotechnical structures like dams, bridges or high-rise buildings requires a sound understanding of the behavior of the soil, the structure itself and the interface. Therefore, a geotechnical instrumentation program can be essential in many ways. During the site investigation stage, it can help determine the initial conditions experienced by the soil in the field by measuring parameters such as the compressibility index or the permeability. During the construction stage, real time measurements can protect the structure from premature failure, help validate and optimize the design if needed. In addition, sensors measuring pore-water pressure, loads, deformations and settlements allow for monitoring the performance of the structure. This is called the observational method. Finally, during the operating phase, instrumentation aims to study the long-term behavior of the structure (Nicholson et al., 1999).

Jan 1, 2019

By Sam X. Yao

In construction of drilled shafts under water, placing concrete in the shafts is technically demanding and involves complex construction logistics. Past construction experience has demonstrated that high quality concrete can be placed in drilled shafts under water with a proper concrete mix and proper placement techniques. However, a significant number of failures have occurred which have resulted in excessive cost overruns and delays. These problems may have occurred because proper underwater concrete construction techniques have not been widely disseminated within the industry. This is a technical area where competent design and sound construction planning can achieve a significant reduction in both risk and cost. This paper will discuss some key technical issues in the concrete mix design, concrete production and placement for the drilled shaft construction. The paper also describes two lesson-learned case histories from drilled shaft construction projects.

Jan 1, 2013

By Anil Bhandari

Using subsurface data collected at each drilled shaft location is an ideal approach for conducting drilled shaft design. However, conducting subsurface tests at each drilled shaft location and subsequently performing the drilled shaft design can be a daunting task for a noise barrier wall that is divided into six (6) sections and stretches for approximately four (4) miles. In addition, having individual drilled shaft designs complicates the construction process. Grouping the subsurface conditions into broad categories and performing the design for each of those categories is an attractive alternative to the design per boring approach. Currently there are no existing guidelines to aid a designer on grouping the subsurface conditions for the drilled shaft design for the noise barrier walls. Therefore, a method was developed based on the Standard Penetration Test (SPT) N values of the near surface soils to categorize the soil profiles into distinct categories. Since the soil engineering properties of the near surface soils are known to be critical for drilled shaft lateral capacity, these soils were emphasized in the methodology. This method was successfully implemented for the design of drilled shafts supporting the noise barrier walls along the I-20 in Columbia, SC. For this project, two distinct soil profiles, labeled as ?strong? and ?weak?, were used. An overview of the soil profile grouping methodology is presented as well as the vertical and lateral drilled shaft capacity analyses for this project for the two general soil profiles. The analyses indicated that the axial capacity governed the design in the ?weak? soil profile and the lateral capacity controlled the design in the ?strong? soil profile. However, this is not a generalization and whether the axial or the lateral capacity governs the design of drilled shaft depends on the soil profile and design loads. Nonetheless, our findings emphasize that both lateral and axial capacity should be checked for drilled shaft design even when the vertical load are minor.

Jan 1, 2011

By Spencer Ness, Yazen Khasawneh, William Tjaden, Mohammad Nassim

The evaluation of long-term performance of the wind turbine structures is essential in lowering the Levelized Cost of Electricity (LCOE) from wind sources. The required maintenance of the wind turbine foundation during the design-life time of the wind turbine may result in escalated cost, if not properly evaluated during the planning and designing phases. The degradation of the foundation soils’ stiffness due to the accumulation small plastic strains resulting from normal and/or extreme operating cyclic loading may result in escalating the O&M cost. The foundation’s stiffness degradation will result in a shift of the wind turbine system natural frequency, which may result in amplifying the vibrations generated at the hub. The anticipated shift of the wind turbine system natural frequency during the design-life time should be investigated through numerical simulations of the anticipated dynamic loading utilizing soil constitutive models that are capable of capturing the foundation stiffness degradation due to the accumulation of such small plastic strains. This study presents the validation of an element model that will be used to evaluate the performance of existing and/or proposed constitutive model.

Oct 1, 2022

By Feng Yongxuan

Anchored sheep pile is normally used in deep excavations, many of which only require stability in accordance with Terzaghi theory. In this paper, based on the experience, new lateral earth pressure method is adopted taking account into interaction among soil, anchors and sheet piles so that a group for the project under very difficult conditions and very severe requirments, especially, for the displacements are determined according to that mentioned above. During and after construction, displacements monitoring were carried out for about four months, which was proved that there was a little difference between calculation and practice.

Jan 1, 1991

By Zhu Tonghao

A method of calculating anti-slide pile, sheet pile, underground diaphragm and structure with anchors etc. is proposeed in the paper. The effect of the various layers of soil, anchors and bracings etc. on laterally loaded structures may be considered in the model. In the analysis the structure is divided into a series of elements. The transfer matrices of both deformation and internal force are established for each element. According to continuous condition neighbouring element should be connected. Thus the deformation and internal force of each element can be found out in conbination with boundary conditions. The method has a wider adaptability and it can be applicable to a great variety of the analysis of interaction between various structure and soil. If parameters in model are selected properly, the computed results would be in good agreement with the measured data.

Jan 1, 1991

By John P. Turner

The behavior of tieback retaining walls depends on many factors, including soil properties, groundwater conditions, construction sequence, spacing and stiffness of tiebacks and soldier piles, tieback loads, and others. The primary design considerations for tieback walls are 1) adequate stability and 2) limiting wall movements. Traditional design methods rely on apparent earth pressure diagrams and experience to predict the forces which must be supported by the tiebacks to provide adequate stability. The required soil properties depend upon whether the soil is sand, soft clay, or stiff clay. Design to limit wall movements is more difficult and the usual approach is to design the wall with an adequate factor of safety for stability and then evaluate wall movements during construction through the use of load tests on individual tiebacks and monitoring of wall movements by optical surveying, slope indicators, and extensometers. If excessive movements are likely to occur, it is often not known until construction is well underway. This approach is reflected in the fact that few tieback walls fail due to a lack of adequate stability, while most litigation involving tieback wall performance is related to excessive movements. Much progress has been made in recent years in methods for predicting the movement of all types of insitu retaining walls (Clough et al. 1989, Clough and O'Rourke 1990). These methods are based upon both experience and analytical methods. This paper reviews the methods currently available for evaluating both the stability and movements of tieback retaining walls. Case histories involving excavations constructed in the downtown Seattle area are used to evaluate the applicability of the available methods to Seattle conditions and to illustrate the importance of soil behavior in tieback wall performance.

Jan 1, 1990

By H. Mori

The session chairman, Dr. H. Mori, welcomed the delegates to Discussion Session 8. AUTHORS PRESENTATIONS 1 . G. Price, Building Research Establishment. UK Mr. Price expanded on the content of his paper and presented elements of various case histories of bored piles instrumented by the Building Research Establishment. In particular, the interpretation of data from instrumented piles is critically related to: (i) the construction process (ii) concrete stiffness and variability (iii) the effects on the pile due to installing instruments The main role of the instrumentation in the examples presented was to establish pile performance under service loading conditions. Of particular interest is the mobilisation of skin friction and soil shear modulus.

Jan 1, 1991

By Richard J. Hartman

This presentation identifies some of the more common problems associated with cofferdam construction. After the various problems are identified, they are briefly explained and possible solutions and preventive measures are noted. Photographic slides used during the seminar illustrate the conditions. This discussion is limited to cofferdams which are braced structures excavated inside to allow access for construction. The common procedure is to drive sheet piling and then alternatively install bracing and excavate. They can be located either on land or in water. Loads are applied by soil, water, surcharge pres-sure, eccentricities, and impact loads. The loads are resisted by the sheet piling, the bracing, and the soil below the bottom of the excavation; each of these three components must be capable of resisting the applied loads.

Jan 1, 1987

By I. K. Ozaydin

Analysis of piles groups loaded with large bending moments and both vertical and batter piles can be best performed by matrix analysis. In this paper, a case history about a tall marine control tower is presented. The soil conditions at the site and the results of the computer analysis of the piled foundation are summarized. It is shown that the pile loads are indeed less than the allowable load for a single pile. Pile head loads and moments are used in the analysis of the raft foundation.

Jan 1, 2010