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By Lawrence F. Johnsen

In 1989, the Connecticut Department of Transportation authorized the evaluation and design for a reconstructed Route 1 bridge over the Quinnipiac River in the City of New Haven, Connecticut. The project extends from the intersection of Route 1 with East Street, easterly for approximately 3/4 mile to the intersection of Route 1 with Wheeler Street and Stiles Street. The reconstructed roadway will be relatively on-line and widened to provide for four lanes of vehicular traffic and a single-track railway line. The existing bascule bridge and approach spans, which were constructed in 1924, will be replaced by a 270-foot span lift bridge and new approach spans. The lift bridge will have a main lift span weighing approximately 3000 tons, second largest after the Burlington Northern Bridge over the Williamette River in Portland, Oregon. The new bridge will widen the navigation channel to 24 0 feet and provide vertical clearances of 13 feet when closed and 62 feet when open. The project is located in an industrial area. Adjacent properties include retail gasoline sales, auto repair, railroad transport and bulk storage of petroleum. Existing structures include the Yale Boathouse and several retaining walls serving as containment dikes for petroleum storage tanks. The Yale Boathouse, located on the east bank of the river, was constructed in 1909-1910 and is eligible for listing in the National Register of Historic Places.

Jan 1, 1993

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

By Marie-Pierre Bourdouxhe-Barnich

Since 1997, in partnership with the Laboratoire Central des Ponts et Chaussées in Strasbourg, ProfilARBED has been carrying out a vast study to qualify the improvements jetting can make to vibratory driving of steel sheet piles, and to understand its effect on the surrounding ground and on the sheet piles themselves. The process basically involves discharging a fluid (mostly water, sometimes in association with air) at controlled pressure and/or flow rate near the toe of the sheet pile being driven. The steel jetting pipes are attached to the sheet pile and are connected to the pumps by hoses. The jet of fluid loosens the soil, thus reducing the resistance at the toe of the sheet pile. Depending on ground conditions, the fluid that flows along the pile can reduce skin friction. Four soil types were involved in our experiments. Each site was instrumented: the driving parameters and the geotechnical characteristics of the soil before and after vibratory driving and jetting-assisted driving were recorded. Each test provided its own particular information which contributes to overall thinking on the matter and is of help to project managers who are often confronted with rapid driving to the final depth.

Jan 1, 2002

By Sam Yao, Ali Naeem, Sara Barrett

Brooklyn Basin Project is a multi-billion-dollar development of the former Port of Oakland 9th Avenue Terminal located along the Oakland Estuary of California. A centerpiece of the development is the 10-acre shoreline park which will be built on a 1,200 ft long by 225 ft wide historic wharf. The wharf was built in the 1930’s on concrete and timber piles with a flat concrete slab. Prior to constructing the wharf, a rock dike was placed to protect the shoreline. The presence of the rock dike increased the hazards from lateral spreading of the underlying bay mud and non-ductile shear failure of piles driven through the dike. To open the park to the public, the wharf required a seismic retrofit in compliance with the California Building Code. The paper presents the results and conclusions of the following topics: • Structural condition assessment and repair strategies for the existing wharf deck, piles and jackets • Application of the California Building Code (CBC Ch31F) for the performance-based seismic evaluation of existing piers and wharves • Nonlinear pushover analysis of the wharf including the combination of inertial and kinematic effects • Impact of rock dike on lateral spreading and kinematic effects and the significance of existing piles in stabilizing the lateral spreading of the rock dike • Retrofit strategies for the wharf to meet the required seismic performance requirements per the California Building Code and reduce the demands on existing piles which were driven through the rock dike INTRODUCTION The 65-acre Brooklyn Basin Development project is located in Oakland, California. The project consists of 3,100 housing units, 200,000 sq. ft of retail and commercial space, along with various parks and public access improvements along the Oakland Estuary. A centerpiece of the development is the 10-acre Shoreline Park which will be built on a 1,200 ft long by 225 ft wide historic wharf. The wharf was built in the 1930’s on concrete and timber piles with a flat concrete slab. As shown in Figure 1, the wharf deck and piles support the 9th Avenue Terminal Building.

Jan 1, 2018

By Frederick C. Rhyner

Drilled shafts have become an economical foundation choice for bridges in the northeast United States, especially when they can be constructed over water without the use of cofferdams. For the Boscawen-Canterbury Bridge over the Merrimack River in New Hampshire, an unusual design was used to avoid the use of cofferdams and avoid the need for pier caps at the waterline. This design used a pair of integral drilled shaft ? columns to form a bent type of substructure for support. Drilled shafts were 8-foot diameter, about 90 feet deep, with 16-foot long rock sockets. These are integrally constructed with 6-foot diameter reinforced concrete columns extending 37 feet from the waterline to the superstructure. Design load cases focused on lateral loads from ice flows, stream flows, wind and seismic events. Alternative analyses using different methods were made to check the design results. This paper discusses the subsurface conditions, design of the drilled shafts and columns, rebar and joint detailing issues, and construction of the drilled shafts.

Jan 1, 2004

By Daryl W. Wurster

The Liberty Bridge in Greenville, South Carolina is a curved, cable-stayed, pedestrian bridge with primary support provided by two towers. The bridge is part of the Falls Park redevelopment. The bridge was originally designed to be supported on drilled piers. Alternately, the bridge was supported on a combination of micropiles and anchor piles because of difficult access and subsurface conditions. The use of micropiles and anchor piles led to improved construction scheduling and reduced costs. Micropiles were used to resist compressive loads. Anchor piles were used to resist tensile forces and to eliminate excessive settlement of pile caps into underlying fill during pre-stressing. This paper describes the site history, bridge construction, site and subsurface conditions encountered, and the decisions that led to support of the bridge using micropiles and anchor piles and foundation construction.

Jan 1, 2006

By J. Brian Anderson

Jointed micropiles were investigated to support bridge foundations where shallow rock was present. In this application, micropiles would have some amount of unsupported length, and would be subject to nominal lateral loads. Five lateral load tests were conducted on micropiles to demonstrate the impact of casing joints and rock socket embedment on lateral behavior. Load tests were simulated with FB-Multipier, a hybrid-finite element program for analysis of deep foundations, for proper design of the loading apparatus and instrumentation. The micropile sections were 2 m (6.56 ft) long, 273 mm (10.75 in) in diameter, 13 mm (0.5 in) thick walled, with a 50-mm (2-in) long threaded joint. Micropiles were made of one to three casing sections and were embedded 0.3, 0.6, 1.5, or 3.0 m (1, 2, 5, or 10 ft) into rock. In each test, two identical micropiles were pulled together using a simple frame until the weaker pile failed. All micropiles were instrumented with inclinometer casings while two contained strain gages at 0.76 m (2.5 ft) intervals. Load and displacement were measured at the pile heads. Tests showed the embedment of 0.6 m, 1.5 m, and 3.0 m (2 ft, 5 ft and 10 ft) sufficiently carried lateral loads over 180 kN (20 tons). The piles embedded 0.3 m (1 ft) were not able to maintain lateral load. In general, all micropiles tested to failure exhibited a brittle failure mode where there is small lateral deflection followed by a sudden failure at the casing joint. This was demonstrated in three of the load tests. In most cases, the micropiles were stiffer and stronger in the load tests than originally predicted numerically. The final test, where piles were not loaded to failure, verified that embedding vibrating wire rebar strain meters in the grout captured the bending moment profile of the micropile. The results showed the maximum moment in this case being carried directly across the threaded joint as predicted by the preliminary models. The results of these tests were used to calibrate the FB-Multipier numerical model. Using a load test that included bending strain measurements for a match, the soil properties were adjusted to produce reasonable matches for all of the load tests.

Jan 1, 2011

By G. G. Goble

Significant progress has been made in the past decade in determining the load bearing capacity of pile foundations. Developments in the means of prediction of pile capacity as limited by soil strength have been substantial, particularly in the use of dynamic methods. The use of currently available equipment, analytical procedures, and practices in the field, will often produce material economies on a job by allowing increased loads with proven factors of safety. This approach justifies the minimum number of piles required for a safe foundation in a wide range of job sizes and soil conditions. To avoid exposing the reader to excessive detail in the body of this paper, technical topics have been covered more thoroughly in several appendices. I. Wave Equation Analysis of Piles Appendix A II. Dynamic Monitoring and the Pile Driving Analyzer Appendix B III. Case Method Capacity Calculation Appendix C IV. Case Pile Wave Analysis Program Appendix D 1 Preliminary Analysis In designing driven pile foundations, there must be a close relationship between design, construction control procedures, driving practices, and the size of the job. Small commercial buildings or residences involving loads that are only a fraction of the pile capacities do not justify the expense of detailed design processes or elaborate construction controls. Nevertheless, some preliminary analysis of the job requirements and a limited subsurface investigation must be made to understand existing conditions and the possible foundation solutions. In other words, it is necessary to determine that driven piling is the best overall choice of foundation.

Jan 1, 1988

By Donald A. Bruce

Pin Piles are small diameter, bored, cast-in-place piles used to underpin structures. They were first employed over 40 years ago in Italy, and have been used in the U.S. since the late 1970's. However, it is only in the last few years that their full potential in terms of load holding capacity has been exploited: whereas 100 kip working loads typified former practice, ultimate loads approaching 700 kips have recently been recorded for Pin Piles founded in sand. In order to better understand the actual performance of these piles, fundamental research has been conducted by a consortium of industry and academia. This paper describes the advances made in the laboratory and full scale field testing programs. In particular, the extensive field tests have been conducted in a variety of materials in which different pile configurations have been cyclically tested to failure. By using this test method, the elastic performance of the piles has been examined and so the progressive interfacial debonding phenomenon has been studied. This has led to the development of the Elastic Ratio concept which is proving extremely useful in analyzing and predicting Pin Pile performance. Data are provided from the full scale Test Pile Programs conducted at Mobile, AL and Port Vancouver, WA. Given that Pin Piles are usually installed in areas of low headroom or restricted access, and through difficult, occasionally contaminated soils, the paper also describes key aspects of construction.

Jan 1, 1993

By J. M. N. P. C. Teles, Venda Oliveira P. J., Correia A. A. S.

"AbstractA laboratory work was performed to study the mechanical behavior of a Portuguese soft soil chemically stabilized with binders and reinforced with metallic fibers when subjected to tensile stresses. To this end and in order to compare the tensile strength results done by two different tests, there were conducted two types of experimental tests: Tensile Split Strength Tests (TS) and Direct Tensile Strength Tests (T). The samples tested had the same binder quantity and different fiber contents, which allowed the characterization of the tensile behavior of the stabilized and reinforced soil, as well as the definition of the best fiber content. Results show that the binder is the main parameter controlling the behavior of the stabilized and reinforced soil until failure, while the influence of the fibers is noticed mainly at the post-failure behavior. The comparison between the tensile strength done by T and TS tests shows that the tensile split test can be used to estimate the tensile strength, although its results are lower than those obtained by the direct tensile tests in general.IntroductionDue to its poor mechanical characteristics, the construction on soft soils presents difficulties that require the use of soil improvement techniques such as chemical stabilization. However, even when mixed with binders, the tensile strength of the stabilized soil is poor, requiring, in certain cases, the use of expensive steel reinforcement or metallic beams, with obvious impact on the final cost of the work. Thus, for the cases where the tensile strength is a design requirement, the soil stabilization should be design with another element, whose primary role is to give tensile strength to the improved soil (Teles 2013).To fill the lack of published studies focused on soft soils both chemically stabilized and reinforced with metallic fibers, the present research aims to analyze the behavior of the improved soil when subjected to tensile stresses. To support the research there were conducted direct tensile tests (T) to directly measure the tensile strength of the samples and tensile split tests (TS) or Brazilian tests to obtain it indirectly. The samples tested had the same binder quantity but five different fiber contents in order to study the influence of the fibers in the improved soil behavior. In addition, a comparison between the results of both tests was made."

Jan 1, 2014

By Henk E. Brassinga

In Rotterdam a number of underground parking facilities have been built and are under development in the inner city, and in the suburbs. These parking facilities are located at already densely built areas. The design of these constructions has to take into account the impact of the building activities and that of the final construction on the surroundings. In this paper some examples of the different building methods of newly realized underground parking facilities are described, and problems that occurred during the construction are pointed out. In the soil conditions as present in Rotterdam the cost effectiveness of underground facilities can be improved by deepening the parking facility, and at the same time reducing the surface area so that the total parking volume remains constant. In this way the total volume of the diaphragm walls and the costs of the project is reduced.

Jan 1, 2006

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 George Piscsalko

There are numerous methods currently available to assess the integrity of drilled shaft and ACIP piles. Each method has its advantages and limitations. This paper will compare the various available methods as well as introduce a new method for assessing integrity of drilled shafts and ACIP piles. This new method, known as Thermal Integrity Profiling, determines the integrity of the shaft both inside and outside the reinforcing cage by measuring the hydration temperature of the concrete along the length of the shaft. These temperature measurements can be made by either passing a thermal probe through a standard Cross Hole access tube, or from embedding thermal wires within the shaft. This Thermal Integrity Profile method will be described in detail and one case history will be presented. Additional testing methods which will be compared include low strain Pile Integrity Testing and Cross Hole Sonic Logging. Advantages and limitations for each method will be discussed.

Jan 1, 2011

By Geoffrey C. Hebner

Augered, cast-in-place piles (ACIP) have become a very common foundation type in Atlanta and the Southern Piedmont Province as well as much of the United States in the past 20 years. Prior to the introduction of ACIP foundations in Atlanta, the most common deep foundation type was Raymond piles. Raymond piles are basically a driven, thin-walled step-tapered steel pile filled with concrete. Drilled piers were also relatively common and continue to be used, particularly in shallow bedrock or high column load situations. Driven piles, including pipes, H-sections, and timber piles were previously common with working loads typically in the 30 to 50-ton range. Initially, ACIP foundations had similar allowable capacities, however, over time improvements in installation techniques and equipment have resulted in an increase in allowable ACIP capacities. Correspondingly, they have become a more cost-effective and trusted foundation for geotechnical and structural engineers. Over the next several decades many other deep foundation alternatives began to lose popularity. ACIP are one of the predominant deep foundations in Atlanta and the Southern Piedmont today. Although ACIP foundations have widespread popularity in the private sector, they have not been readily accepted currently by government transportation agencies. ACIP may be used by some of the smaller municipalities, but to the author's knowledge, have not been used with regularity by larger, state agencies.

Jan 1, 2003

By Joram M. Amir, Ernst Niederleithinger, Nikolaus Schneider

"Abstract: Diaphragm walls are used to provide a stable and watertight confinement for the construction of tunnels, underground railway stations, deep basements and other structures requiring deep excavations. Water seepage and soil loss through the joints have occurred on several occasions, causing extensive damage. This may have been due to uncontrolled concrete flow between the joints, unexpected geologic conditions or just poor workmanship.Different ways of quality assurance are applied on construction sites. Most of them rely on recording parameters of the construction equipment and conventional concrete quality control. In the frame of the EUREKA/ZIM project DiWaQ we have looked at several ways to perform non-destructive quality control. Some methods are to be applied after excavation before concreting (phase 1); others after the wall is completed (phase 2).For phase 1 we have used two different principles for checking the shape of the excavation, especially the joint to existing panels. A mechanical device which can be adapted to the excavating equipment was developed; field tested and validated on test and construction sites. It is described in detail in another paper in the same volume. A sonar-based device with a 10 mm resolution has shown good performance in the lab, but is still under development.For phase 2 different temperature sensors have been lowered into access holes to monitor the hydration heat developed during concrete curing. The same tubes can also be used to perform electromagnetic and ultrasonic crosshole measurements across or along joints to detect flaws. Especially the ultrasonic method has shown promising results on validation specimen at the BAM test site at Horstwalde, but limitations as well. Success substantially depended on the joint type, flaw size and distance of the sensors to the joint."

Jan 1, 2014

By Tomohide Takeyama, Yuki Yoshida, Masaki Kitazume

"Abstract A series of centrifuge model tests was conducted to investigate the failure pattern and stability of cement treated clay ground having an unsupported vertical slope. The model ground was subjected to monotonically increasing centrifugal acceleration until it failed due to the enhanced self-weight. The test results were compared with the numerical analyses in which the treated soil was simulated by the Smoothed Particle Hydrodynamics (SPH) method. In the simulation, the Dracker- Prager model is employed as the constitutive model. In order to simulate the brittle behavior of the cement treated soil, it is assumed that the unconfined strength is gradually reduced to a certain value which corresponds to the residual strength due to accumulated plastic strain. It was found that the simulation by using SPH method can express the brittle failure observed in the centrifuge model tests.IntroductionBecause of economical and environmental concerns it has become more difficult in recent years to obtain enough soil to construct reclaimed land for airports, electric power plants, manufacture plants and so on. On the other hand, it has become difficult to find and construct disposal sites for waste subsoil or dredged soil. These circumstances have encourage geotechnical engineers at present to use these poor quality materials as filling materials more than they were used one or two decades ago. Several soil admixture methods have been developed to improve their properties and to manufacture high quality fill materials.The deformation and strength characteristics of cement treated soils have been investigated in Japan, which have revealed that the treated soil is characterized by a brittle behavior with quite high compressive strength and quite small strain at failure, and the treated soil with relatively high strength shows tensile failure instead of shear failure. Regarding to evaluate the stability of structures adjacent to or buried in the treated ground, Kitazume (1998) and Kitazume et al. (2003) investigated the earth pressure of cement treated ground by the centrifuge model tests. And they emphasized that the failure pattern of the cement treated ground was much different from that of ordinary ground. After the Hyogoken- Nambu earthquake in 1995, many design codes for the seismic stability were revised in Japan, so that seismic stability must be evaluated more precisely. The dynamic earth pressure of ordinary grounds is usually calculated by a pseudo-static limit equilibrium method based on the Mononobe- Okabe’s method (Okabe, 1924; Mononobe and Matsuo, 1929). This calculation method is also applied to the cement treated ground, although its applicability has not been thoroughly clarified."

Jan 1, 2014

By Lars Richter, Franz-Werner Gerressen

"The Eglinton Crosstown Line was conceived as the Eglinton Crosstown LRT, a partially underground light rail line, announced in 2007 as part of the Transit City plan, which included the implementation of six other light rail lines across Toronto.There were 43 stops planned for the Eglinton Crosstown LRT, 13 of which would be underground . For those underground stations a lot of specialty foundation works needed to be carried out. King piles, soldier piles with lagging and secant piles were mainly required fulfilling the tasks of installing the retaining wall system.The paper will focus on the original design and alternative solutions, discussing the benefits and limits of these. It will also explain the installation process in general as well as some specific features related to specific site conditions, e.g. limits in installation depth, soil characteristics etc. The required equipment will be explained showing the benefits and limits.INTRODUCTIONThe Eglinton Crosstown project is a 19-kilometre LRT line that will bring much needed relief to the transit woes of Torontonians. Traversing the city in an east-west slice across the midtown artery of Eglinton Avenue, the Crosstown rail line involves a combination of 15 underground stations and 10 atgrade surface stops. It is one of the largest transit infrastructure projects under way in North America today. Aecon has joined partners ACS Infrastructure Canada, Ellis Don, and SNC-Lavalin to form Crosslinx Transit Solutions (Crosslinx).As with many of today’s mega public transportation projects, the Crosstown LRT follows the Public- Private Partnership (P3) model. Aecon is an equal partner in the $5.3-billion Crosslinx consortium to develop the Eglinton Crosstown LRT project in Toronto. Upon the LRT's completion in 2021, Metrolinx, the region’s transit authority and also the project client/owner, will turn to the Toronto Transit Commission (TTC) to operate it. The impact of this highly anticipated LRT line on commuters in the Greater Toronto Area (GTA) is expected to be dramatic and immediate once the first train leaves the station five years from now. In fact, Metrolinx is estimating that within its first 10 years of service, the Crosstown line will be carrying 5,500 passengers per hour (in peak direction) and making 100 million passenger trips annually."

Jan 1, 2017

By J. Stacho, Frankovská. J.

"Abstract The use of continuous flight auger (CFA) piles in Slovakia has increased significantly in recent decades. High-rise building of administrative centre Lakeside Park in Bratislava is based on piled-raft foundation. The technology of CFA has been used due to the advantages of this technology in comparison with driven and bored piles in local geotechnical conditions. Piles have been designed in accordance with Eurocode 7. Resistance of piles was calculated by using an analytical calculation model for bored piles according to Slovak technical standard and CFA technology has been taken into account by coefficient equal to 1.1. Settlement of piles was calculated by using a calculation model which is being used in Czech Republic and Slovakia. Two well instrumented static load tests were carried out to verify the pile design. The results of static load tests showed that the design was conservative. The paper presents analysis of numerical modelling of CFA pile and static load tests. Load-settlement curves and load distribution curves over pile shafts are compared. Software Plaxis 2011 has been used for numerical modelling. Hardening soil model allows considering over consolidation of Tertiary Silts and water pressure in deep sandy lenses. The article also presents the parametric study where the influences of pile-soil interface reduction factor, over consolidation ratio and material models of soils are analysed. The results of numerical modelling showed that the most appropriate results have been obtained when the interface reduction factor equal 0.9 and real behaviour of groundwater were considered. The conclusion of the paper confirms that mechanical behaviour of the ground can be better understood and determined by using FEM than analytical methods.1. IntroductionPiles are among the most frequently used elements of deep foundations. Piles transfer loads down to a suitable bearing stratum when the soil immediately below a construction is unsuitable. Piles are also used to reduce settlement of structure. At present, the requirements of limit settlement of structures are more stringent. Examples of these structures are commercial and administrative centres that form a complex of different tall buildings. High-rise buildings cause greater contact stresses than connected low-rise buildings. Pile foundations in such cases should be placed under the high-rise buildings to achieve an appropriate settlement.Resistance of piles can be determined from static load test results, in-situ tests and empirical experiences or calculations. Static load tests give the most reliable results, but these tests are also the most expensive. This is the reason for constant development of computational methods. Especially numerical methods give more accurate results by using more sophisticated material models e. g. hardening soil or hypoplastic model."

Jan 1, 2014

By Mark H. Balfe

Over the last decade, Fenway Park has undergone annual improvements to modernize the facility for players and fans. These renovations include the Monster Seats, the Right Field Roof expansion, a new pavilion behind home plate, expansion of the Red Sox clubhouse, additional roof seating, and concourse improvements. Retrofitting the historic ballpark to bring it up to current standards required installation of foundations to support the new structural loads for each of the alteration projects. This required evaluation of existing conditions, and in many cases augmentation of the foundations at existing columns to accommodate the structural changes to the park. New foundations, generally consisting of drilled-in micropiles, were installed in numerous configurations and conditions. Since 2003, a total of 215 drilled-in micropiles have been installed to augment various columns around the park. The micropiles range in capacity between 40 and 70 tons and are installed through Fill and Organic Soils and embedded into the dense Glaciofluvial Sand and Gravel layer. Issues and learning related to the foundation augmentation include schedule constraints (work is typically conducted during the off-season and schedule is very aggressive), encountering old/abandoned utilities or foundations, ventilation of equipment, and management of spoils during micropile installation.

Jan 1, 2011

By Michal Topolnicki

"Discussed is the use of wet Deep Soil Mixing, generally executed with single mixing tools 0.8 to 1.6m in diameter, employed in the foundation of viaduct supports. The applications involve economical patterns of ground improvement, covering in average about 40% of the foundation area or less, which contribute to the competitiveness of DSM solutions when compared to traditional piling. The focus is on selected aspects of the geotechnical design, applicable for geo-composite systems in which the interaction between the stabilised and the native soil should also be considered. Evaluation of settlement can be carried out with simplified methods, accounting for punching effects, or with more advanced FE models in case foundation tilt or differential settlements become important. Potential bending of DSM columns should be considered when evaluating column stresses, especially when dealing with deep deposits of soft soil and/or foundations loaded with overturning moments and/or high horizontal forces. Statistical evaluation of UCS data using lognormal distribution is recommended, and a new classification system for DSM application is proposed. Field investigations and monitoring data from completed projects are also presented.INTRODUCTIONThe first applications of wet Deep Soil Mixing in foundation of road viaducts constructed across and along the newly built A2-highway in Poland took place in 2002. Following detailed analyses, it was concluded that 39 viaducts, originally designed to rest upon large diameter piles in order to reduce excessive settlement of individual supports, could also be founded directly on the ground improved with DSM columns, fulfilling all relevant requirements of serviceability and ultimate limit states (SLS and ULS, respectively). It was also noticed that shorter construction times and lower costs of ground improvement with DSM contributed to substantial economical savings as compared to classical piling. Since then, more than 250 road and railway viaducts have been successfully founded on DSM treated ground in Poland, and wet soil mixing is now seen as a reliable and widely accepted technology for this purpose. These applications, together with a parallel use of wet DSM for foundation of buildings, industrial halls and wind turbines, have drawn international attention to the state of practice of wet DSM in Poland for foundation of engineering objects. What follows is an attempt to summarise experience gained during planning and execution of DSM works for foundation of the majority of road and railway viaducts constructed in the last 13 years, with emphasis on selected design aspects and evaluation of collected data and observed performance.The design process of DSM treatment is iterative, as described e.g. in Annex B of EN 14679, and typically involves two main steps, i.e., the selection of the design strength of cemented soil, called soil-mix design, and the adoption of suitable column pattern, referred to as geotechnical design. Soil-mix design was initially based on purposely arranged simple laboratory tests, involving mixing of soil specimen with different cement types and dosages and subsequent strength testing. However, with a growing number of completed projects the accumulated field strength data of different stabilised soils have been more and more frequently used, reducing the need for preceding laboratory testing of soil-mix to special projects only. Information on cement factors utilised in Poland and the range of recommended compressive strengths for different stabilised soils, as well as on mixing tools and characteristics of the wet method applied, can be found in Topolnicki (2008). Consequently, soil-mix design is not further discussed herein. Selected aspects of the geotechnical design are the main focus."

Jan 1, 2015