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By Martin J. Pedley

The use of soil nailing has grown steadily in the UK over the last 15 years and it has recently become more popular in the Republic of Ireland. This paper presents three soil nailing temporary works case histories where the technique has been used to support steep excavations in difficult ground conditions. It demonstrates the effectiveness of soil nailing when applied in appropriate conditions. Details of design methods and construction techniques are described and those aspects of soil nailing that will benefit from further study and development are identified.

Jan 1, 2000

By Ganesh Kumar S.

"Soil reinforcement using stone columns is one of the well-developed ground improvement techniques for soft clay deposits. The load carrying capacity can be further improved by encasing it with geosynthetic material around the column which offers effective lateral confinement, prevents column contamination with improved drainage and strength characteristics. Improvement of undrained shear strength using vacuum consolidation is a type of hydraulic modification technique in which negative pore pressure will be developed which increases the effective stresses in soil without changing the total stress. The improvement in effective stress resulted in improved undrained shear strength of surrounding soil. In this research work, combined geosynthetic encased stone column and vacuum treatment method is examined for improving of extremely soft clay soils. The improvement in the time rate of consolidation and load carrying capacity of stone columns after vacuum treatment was studied using experimental investigations. It was observed that both load carrying capacity and stiffness of the encased stone column increased significantly with vacuum application. Also, application of vacuum accelerates rate of primary consolidation settlements. With this reduction in time, the construction activity can be accelerated which makes the project economically beneficial.INTRODUCTIONThe rising demand for the land for country’s infra-structure compels the engineers to work with even soft clay deposits which are not suitable for construction activities. As these soils have low bearing capacity and excessive settlement characteristics, ground improvement methods will be required before commencing construction. Among all available treatment methods, soil reinforcement and hydraulic modification technique are well-known popular techniques for its reduction in time required for consolidation settlement with improvement in load carrying capacity. When stone columns are used as a reinforcing member, it creates drainage with improves bearing capacity (Greenwood, 1970; Mitchell & Huber, 1983). However, the limitation includes lack of lateral confinement in very soft clay deposits, possibility of contamination, reduction in drainage path all which leads to the failure of stone columns (Mckenna et al, 1975). To overcome these limitations, encasement using geosynthetic material was adopted around the column which offers better lateral confinement, prevents intrusion of finer clay particle inside the column and provides effective drainage path with improved load bearing capacity characteristics (Van Impe, 1986; Raithel et al. 2005; Short et al. 2005; Borkemper et al. 2006; Murugesan & Rajagopal 2010; Kumar et al. 2014)"

Jan 1, 2017

By Seffen Leppla, Rolf Katzenbach, Matthias Seip

"Abstract The economic and safe design of deep foundation systems in difficult soil conditions is based on a reduction of construction material used, construction time spent, energy consumed and a high-level modelling of the soil-structure-interaction. The special foundation system Combined Pile- Raft Foundation (CPRF), in-situ load tests on the construction site and a sufficient soil investigation allow cost optimised constructions. In any case at challenging projects the observational method has to be applied for verification and quality control of the design. Regarding the 4-Eye-Principle as basis of the quality control management an independent peer review of the planning, design and construction phases is the guarantee for safety, serviceability and optimisation of all projects. Main execution standards for the construction of deep foundations based on the Eurocode 7 are summarised and discussed. The paper presents the basics of the safe and qualified design and construction of foundation systems including quality assurance. The application in engineering practice is shown on achallenging project of high-rise buildings with difficult boundary conditions.IntroductionThe construction of deep foundation elements in inner cities are special challenges due to the limited space for the construction works and the effects on existing buildings (Figure 1).An economic and safe design of deep foundation systems in difficult soil conditions is based on the following main aspects:•,qualified experts for planning, design and construction•,interaction between architects, structural engineers and geotechnical engineers•,adequate soil investigation•,design of deep foundation systems using the Finite-Element-Method (FEM) in combination with•,enhanced in-situ load tests for calibrating the soil parameters used in the numerical simulations•,quality assurance by an independent peer review process (4-eye-principle) combined with theobservational method if necessary"

Jan 1, 2014

By A. Lyndon

Combined loading tests are described to three 1.2m diameter cast-in-place bored piles, 12m long, formed through cohesionless material into stiff sandy clay. The maximum loading conditions imposed at the pile head were 2400 kN vertical, 160 kN lateral and 3120 kNm in bending, corresponding to twice the working load. Settlements, deflections and rotations of the piles were measured during the tests. An interesting finding which the test results suggest is that, in the short term, vertical movement had apparently no marked effect on lateral performance for piles working at design loadings.

Jan 1, 1989

By J. Matos e Silva

"Abstract Although one can think that it is very low the probability of a seism occurrence during the execution of an excavation in an urban lot protected by a diaphragm wall curtain, reality shows that whenever a seism occurs in an urban area several diaphragm walls will be affected by it. So it is advisable to consider the seismic action when designing a diaphragm wall curtain. The paper refers the main information about the seismic design of diaphragm walls according to the Eurocodes 7 and 8 and to the Portuguese Norms related to them (respectively NP EN 1997-1 2010 and NP EN 1998-5 2010), as the Eurocodes consider the possibility of each European country to adopt their own seismic parameters as the seismic risk is different in each country. Thus the so-called National Document of Application (in our case the Portuguese Norms) prescribes the seismic local parameters.1 - EUROCODES AND PORTUGUESE NORMS PRESCRIPTIONSAccording to Eurocode 8 - Part 5 and to the related Portuguese Norm NP EN 1998-5 2010, seismic actions on soils should be quantified adopting the Mononobe-Okabe method that gives goodapproaches when compared with reality.From paragraph 7.3.2.2 of the referred Norm, the horizontal seismic coefficient kh will be:"

Jan 1, 2014

By David G. Winter

The first test pile for the carrier pier and south wharf at NAVSTA Puget Sound was driven on December 27, 1989, and the final pile was tested on February 26, 1990. Implementation and modification of the test pile program were done by the owners (WESTDIV and ROICC-Everett), the engineers (ABAM and Hart Crowser), and the contractor and his subcontractor (General Manson Joint Venture and GRL). The site is located as shown on Figure 1. SUMMARY OF THE SOIL CONDITIONS A soil profile along the pier is shown as Figure 2. The soil units can be generalized as follows: ? Upper Silts - Fill, sandy silt, and clayey silt extending from the mudline to an elevation of about -80 feet; ? Intermediate Sand - A medium dense to very dense silty sand unit which is about 30 feet thick near the shore, but thins and disappears offshore; ? Lower Silts - Sandy silts and clayey silts in a medium stiff to stiff condition; ? Deep Sand - A very dense overconsolidated sandy soil encountered at an elevation of about -145 feet.

Jan 1, 1990

By Stefan Larsson, Sebastian Adevik, Sadek Baker, Razvan Ignat

"Abstract Uncertain strength, deformation and flow properties in dry deep mixing columns often lead to conservative choices concerning design values where the design is regularly complemented with a surcharge fill. The surcharge not only leads to increased cost but also to logistical problems where the surcharge is a physical obstacle. The deformation properties of a ground improvement were studied by means of two small embankment load tests. The settlement measurements were also used in FEM analyses, where the effect of surcharge on creep settlements was investigated. Based on the results, the effects of the surcharge were considered negligible and could safely be ignored. The project is an example how the contractor can use a field test as an effective design approach.IntroductionGround improvement of soft soils with dry deep mixing columns, or lime-cement columns, is often combined with a surcharge fill. The main reason for using a surcharge is to force the primary settlement and some of the secondary settlement that would have occurred under the final embankment height alone, to take place under the surcharge loading. Another reason is to level out uneven settlements. Strength and deformation properties in improved soil cannot be sufficiently assessed in advance, before columns have been tested on-site, and this uncertainty often lead to conservative choices concerning design values. In order to compensate for a slow forecasted consolidation process, the design is regularly complemented with a surcharge. The surcharge not only leads to increased cost but also to logistical problems where the surcharge is a physical obstacle.Extensive research undertaken by Åhnberg (2006, 2007) shows, by means of triaxial and oedometer tests, that cementation processes and a load acting on the columns during hardening, makes the improved soil to behave as a heavily over-consolidated soil due to an increase in quasi pre-consolidation pressure. The effects of using a surcharge on the time for consolidation and creep properties are thus probably small, since the stress level does not normally exceed this quasi pre-consolidation pressure. A study presented by Venda Oliveira et al. (2013) shows that the stress level within small ranges has limited effect on the creep properties.This paper presents a case study where the deformation properties of a ground improvement using dry deep mixing columns was investigated by load tests on two small test embankments. The tests were performed at the Interchange Värtan project site, which is part of the Norra länken infrastructure project in Stockholm. The tests were not performed as a research project but simple load tests performed by the contractor with the purpose of rationalizing the design delivered by the client. One purpose of the load tests was to assess the deformations when the columns are loaded temporarily by overlaying concrete works. Another purpose was to provide some input data to a study of the effects of using surcharge on creep settlements. The analysis was conducted as finite element modeling using the commercial code PLAXIS, where creep settlements can be simulated using the built-in Soft Soil Creep model."

Jan 1, 2014

By Richard Short

Shallow rainfall-induced landslides in residual and colluvial hillslopes and steep embankments are a common occurrence in many settings [1, 2, 3]. While occasionally posing a threat to property and life-safety, they more often present an ongoing maintenance problem and can lead to the initiation of larger failures. Typically, these slides consist of 2 to 4-foot thick translational movements of silty and clayey soils down slope through the reduction of strength from increases in pore water pressures. Direct surficial infiltration and indirect groundwater seepage are the normative triggers for failure. In the residential community of Blackhawk, California, located east of the San Francisco Bay, these types of landslides are a common occurrence (Figure 1). However, shallow landslides have also been a repetitive and constant problem along many state highways where steep embankments have been constructed in close proximity to busy thoroughfares. Given the real threat to property values in residential and commercial settings and the constant maintenance problem posed to lifeline structures such as utilities, roadways, and pipelines, new methods to deal with these landslides are needed.

Jan 1, 2007

By Bret N. Lingwall, Byron Foster

The problem of reliable extreme event modeling of large diameter piles under enormous structural or kinematic loads has gained more attention in recent years. In particular, the soil response around the foundation and impacts to buried adjacent infrastructure has gained interest. One of the principal shortcomings with analysis of large diameter pile foundations under extreme event lateral loading is the reliance on conventional beam on elastic foundation methods, which do not model the soil field response around the pile. These methods are limited for large displacement problems, and for large diameter piles. However, the fundamental interactions between steel and concrete, and structure to soil are difficult to constrain, especially in large strain problems where the structural elements become inelastic. The non-linear interaction of the structural materials and soil is desirable so that assessment of stress changes in the field and effects on adjacent facilities can be modeled. A numerical modeling methodology that addresses these shortcomings has been developed. This method utilizes the interaction of brittle concrete with discrete steel reinforcing and casing in a robust manner capturing inelastic non-linearity in both soil and structure. This paper presents a comparison study of the method, wherein three different validation studies were made to data from full scale laterally loaded pile testing. INTRODUCTION Extreme event lateral loading of deep foundations comes in many forms including earthquakes, landsliding, tsunamis, hurricanes, surface fault rupture, liquefaction induced lateral spreads and many more. These extreme events induce loads on foundations far greater than service or strength loads. Perhaps the most dangerous extreme event loads are those of large soil displacements such as landslides, lateral spreads, and surface fault rupture, wherein the soil surrounding the foundations can move laterally 100 mm to 3 m! In these extreme event loading scenarios, small diameter foundations are pushed past their limits and many engineers prefer large diameter deep foundations for these situations. These deep foundations of diameter 900 mm or greater may be auger cast in place piles, cast in drilled hole piles, cast in steel shell piles, cased or uncased drilled shafts, bored precast piles, etc. For convenience in this paper, large diameter deep foundations will be referred to as Large Diameter Shafts (LDS). In LDS, steel may or may not used as a shell around the perimeter of the concrete and/or as internal tensile reinforcement. The interaction between brittle concrete and ductile steel within and/or along the perimeter of the LDS is critical to understanding the non-linear inelastic behavior of LDS for problems of large lateral displacements from extreme events.

Jan 1, 2018

By Jean-Louis Briaud

The following is a summary of a very recent report prepared at Texas A&M University for the National Cooperative Highway Research Program and entitled "Downdrag on Bitumen Coated Piles". Anytime the soil settles more than the pile, downdrag or negative skin friction will develop. The load in the pile increases with depth up to a certain point and then decreases down to the pile point. This phenomenon has been quoted as being the number one culprit for deep foundation failures. In Chapter 1, an introduction to downdrag is given. The most common criterion for downdrag is to consider it in design as soon as the settlement of the soil surface after pile driving exceeds 0.5 in. Coating piles with bitumen is an effective way of reducing downdrag forces and therefore allows to use smaller piles for the same load. This results in cost savings. Coating piles with bitumen increase the cost of piles by about 33% and therefore the decision to use bitumen is generally based on economic considerations.

Jan 1, 1989

By Brian R. Zuckerman

The Capitol Area East End Complex is currently being constructed under contract with the State of California Department of General Services on two sites adjacent to the grounds of the California State Capitol Building in downtown Sacramento. The complex will consolidate the headquarters of the Departments of Health Services and Education, which currently occupy several facilities located throughout Sacramento. When completed in 2003, the complex will be the largest civic office project in California history, with approximately 1.5 million square feet of office space and housing nearly 6,300 state workers. The total project is being constructed on five separate blocks in downtown Sacramento, Blocks 171 through 174 and 225. Separate design/build contracts were executed for the construction on Blocks 171 through 174 and the construction on Block 225. The scope of this paper is limited to construction on Blocks 171 through 174, which comprise a square, two blocks on a side, bounded by 15th, 17th, L, and N streets, located immediately to the east of Capitol Park and the State Capitol Building, as pictured in the image shown below.

Jan 1, 2002

By Harpal Parmar

This paper evaluates dynamic methods of pile capacity prediction by comparing their results to static load test results. Dynamic and static pile load test data were assembled from four southeastern states of the U.S. End-of-drive and restrike capacities were evaluated using the Pile Driving Analyzer (PDA) and by wave equation (WEAP) analyses. These were compared to static (Davisson criterion) loads. The best comparison was obtained for restrike PDA results; restrike wave equation analyses values also compared well. The end-of-drive results for both methods-showed relatively poor comparisons. The PDA was recognized as an important tool to measure energy transferred to the pile; this transferred energy was recognized as an uncertainty when conducting wave equation analyses. A statistical analysis showed restrike capacity results to be associated with higher precision and accuracy as compared to end-of-drive methods. The authors believe that restrike dynamic testing is essential to establish long term static soil strength and that it will lead to accurate and cost-effective design of piles.

Jan 1, 1996

By Drew Floyd

Five full-scale pile load tests were performed on pairs of PZ-22 sheet piles installed with a vibratory pile driving hammer. The sheet piling was installed in several locations in soil generally consisting of miscellaneous granular fills overlying soft organic silts, inorganic silt interbedded with sands and gravels, very dense glacial till and shale bedrock. The test program also included the use of tip tell tales to determine what capacity could be attributed to tip resistance and skin friction. During the design phase of the project, it was assumed that the capacity of the sheet piles driven with the vibratory hammer could be correlated with the rate of penetration. The correlation between vertical capacity and rate of penetration would be used as a basis for determination of a driving criteria from driving the production sheet piling. The sheet piling load tests demonstrated that it was not possible to correlate the capacity of sheet piling driven with a vibratory hammer and the rate of penetration. It was also demonstrated that the capacity of the sheet piles was directly related to the density of the soil at or just below the tip. The results also tend to agree with empirical equations provided by Meyerhof (1976).

Jan 1, 1989

By Mazin Adnan

The 80m high dam at the Peribonka river in the Canadian province of Quebec was designed for the generation of 385 MW of hydro electrical power (Fig.1). The complex ground conditions required the employment of a variety of geotechnical construction methods stretched to limits never experienced before. Innovative grouting and trenching techniques were used for the construction of a plastic concrete cut-off wall down to a depth of about 116m, to cut hydraulic seepage through alluvial deposits forming the dam foundation. The bedrock where the cut-off wall is embedded forms a glacial gully with steeply sloped flanks, which created further challenging conditions. [ ]

Jan 1, 2008

Jan 1, 2002

By David R. Beadman

This paper discusses how modern techniques of design and construction were used to create the deep stations for the Copenhagen Metro. The deep stations are located in small squares within the city adjacent to many old and sensitive buildings. The architectural design provides a large open atrium to allow natural light to reach the column free platforms to give the citizens of Copenhagen a feeling of safety and security and encourage them to use the Metro. The design and construction contract was undertaken using the relatively new and untried Eurocodes. The resulting stations set new standards of design for underground metros and have pushed forward the frontiers of what is appropriate construction practice to protect the existing and enhance the future environment.

Jan 1, 2000

By Michael Lane

With the success of their existing casino operation on the Ohio River in Lawrenceburg, Indiana, the Indiana Gaming Co., LP planned a major expansion of the current facilities. This expansion includes a second 1400+/- car parking garage, a new surface parking lot, elevated walkways, and a new floating casino that will double their present square footage and consolidate all of the gaming activity to one floor. In March of 2006 Richard Goettle, Inc. was awarded the general contract to construct a 260? x 520? boat slip for the new Argosy VII floating casino. An Open Cell® bulkhead system was specified as the means for constructing the new slip. Our contract included the purchase and installation of 300,000 square feet of PS27.5 sheet pile, excavation of 230,000 cubic yards of soil, and a 3300 square foot Mechanically Stabilized Earth wall.

Jan 1, 2008

By S. H. Miller

Biodegradable hydraulic fluids can save tens or hundreds of thousands of dollars in fines and clean up costs in the event of a hydraulic fluid leak or spill. When properly selected, applied, maintained and monitored, a biodegradable fluid will have a long useful life and will protect equipment as well as or better than conventional petroleum based hydraulic fluids.

Jan 1, 2000

By F. Z. Suo

Baoahan Iron and Steel Complex is situated at lower beaches of the Yangtze River. The subsoils 50~70 M below the surface is a deposite of Yangtze River delta, consisting mainly of weak silty clay and loam, with low soil bearing capacity. Consequently, to build on such a weak soil a grant iron and steel integrated works weak soil improvement at the Complex, pile foundation is the effective type. It is estimated that at the first stage of Baoshan project 60,000 piles have been driven, of which 60% are steel pipe piles and 40% reinforced concrete piles. To provide reliable basis for pile foundation design, on-site loading tests were carried out for long reinforced concrete piles 27,45 60 M in length ,with strain gauges on the chief reinforcement of pile shaft and strain rod on pile tip. Based on loading tests, the paper discusses and analyses some issues, including determination of load transfer mechanism distribution of frictional resistance. Tests show that as far as long friction piles in soft clay are concerned, regardless of the properties of pile tip's bearing stratum, loads are mainly carried by shaft frictional resistance which it is effective to determine pile capacity in terms of P ~ S relationship.

Jan 1, 2010

By M. England

A method for the analysis and prediction of single pile displacement behaviour is described. It is the displacement in time, under constant load, based on the use of hyperbolic functions to characterise individual constituents of the displacement-time behaviour. Extensive use of this technique has confirmed its validity in a variety of soils and that consolidation and creep settlement appear to be indistinguishable. The algorithms employed are suitable to model the displacement behaviour from the onset of load to infinite time for all types of piles and surface foundations. Until the advent of computer controlled static load testing, analysis of the displacement-time characteristic during pile load tests has been hindered by the quality of the data recorded and inconsistency of loading. This has hitherto made the development of suitable behavioural models very difficult. Understanding the soil deformation within a proper time framework allows the subject of pile instrumentation and testing to be developed. The equipment required is basically a computer controlled loading and pile head displacement measuring system which allows accurate analysis of the settlement characteristic in almost every situation.

Jan 1, 1993