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By Anne Lemnitzer

When a major storm system stalled over Western Europe last summer, it pro- duced the deadliest flood on European territory in the last two decades. Beyond record-setting rainfall over countries such as Luxembourg, Switzerland, France and the Netherlands from the storm's "Bernd" low pressure system, more than 230 people were killed in Germany and Belgium. The storm system also caused over an estimated $20 billion (€17.7 billion) of damage. A team from the Geotechnical Extreme Events Reconnaissance (GEER) Association, supported by the National Science Foundation, was mobilized to investigate the potential impacts of the widespread flooding in Germany, Belgium and the Netherlands. Members of the DFI Europe regional chapter closely collaborated with the U.S.-based GEER team and many other engineers and scientists in Europe to collect perishable data and study flooding effects and the event's resulting impacts on geostructures, such as bridges, retaining walls, dikes and embankments. This article features some of the vast information collected by the team, which has recently been published in a comprehensive reconnaissance report and made available for free at geerassociation.org. All data will also be accessible at the NEHRI DesignSafe Cl data repository.

Feb 1, 2022

By Renee Fippin

Several projects are underway in Nassau County, New York, to improve water quality in the Western Bays of Long Island. A major piece in accomp­lishing this is the Bay Park Conveyance Project. When completed, it will divert most of the treated effluent away from the Western Bays to an existing ocean outfall at the Cedar Creek Water Pol­lution Control Plant. The ongoing works include 3.6 mi (5.8 km) of micro­tunneling, 7 mi (11.3 km) of sliplining, 14 shafts and a 75 million gal (284 mil­lion L) per day pump station. In February 2021; Western Bays Constructors (WBC) - a joint venture of John P. Picone and Northeast Remsco Construction - was awarded the design-build contract. For final design, WBC retained Delve Underground to lead the design team for the project. Delve Underground worked in concert with WBC and its subcontractor, Keller, to determine optimal shaft construction methodologies, and during tender, evaluated options that would limit groundwater inflows to the allowable limits. This article focuses on how support of excavation {SOE) was selected for the 14 primary shafts for the microtunneling efforts as well as key design components to address shaft performance needs.

Feb 1, 2024

By Don C. Warrington

This paper describes a new wave equation analysis program called ZWAVE, which is a program specifically for external combustion hammers. The program is de-scribed in detail, the discussion dealing with topics concerning the program such as 1) the numerical method the program uses to integrate the wave equation, which is different from most other wave equation programs; 2) the modelling process of both cushioned and cushionless hammers; 3) the automated generation of mass and spring values for both hammer and pile; 4) the method of dealing with plastic cushions; 5) the use of a recently developed model for computing shaft resistance during driving; 6) the computation and generation of values based on basic soil properties such as shear modulus, Poisson's Ratio and soil density; 7) the completely interactive method of feeding data to the program; 8) the method used to compute the anticipated rebound and the energy used to plastically deform the soil; and 9) the format of the inter-active input of the program and the program's output. Sample problems for the program, along with comparison of the program results with data gathered in the field, are presented.

Jan 1, 1988

By Shoichi Tsukuni, Akihiko Uchida, Kazuo Konishi

"In order to investigate the effect of grid-form deep mixing walls as a countermeasure for liquefaction damage to roads and private houses in Urayasu, Japan, three dynamic centrifuge model tests were conducted. Urayasu is located in the Tokyo Bay area, and private houses in the city incurred severe damage due to liquefaction during the 2011 Tohoku earthquake. In grid-form deep mixing walls design, the distance between grid-form walls is critical to prevent liquefaction. This study clarifies the relationship between the settlement of private houses and the distance between grid-form walls under the conditions that exist in Urayasu.INTRODUCTIONMany private houses in Urayasu, Japan suffered severe damages due to liquefaction during the 2011 Tohoku earthquake (Photograph 1). Fig. 1 shows the location of Urayasu and the maximum acceleration of the observed seismic waves in the Tokyo Bay area. At Urayasu, the duration of the seismic waves (hereafter called the Urayasu Wave) was about 2 min. The maximum acceleration was 1.57 m/s2 (Fig. 2), which is relatively small. The damages occurred in the land reclamation areas that consist of loose sand with an SPT-N value less than 10.To prevent liquefaction in future, it is necessary to adopt suitable countermeasures in the areas where many private houses suffered severe damages. Grid-form deep mixing walls are one such countermeasure. Fig. 3 and Photograph 2 show grid-form deep mixing walls. Walls are constructed using the deep cement mixing method. Fig. 4 shows a plane view of planned grid-form deep mixing walls for roads and existing private houses in Urayasu."

Jan 1, 2015

By Anthony T. C. Goh

"For deep excavations in soft clay, it is common to use jet grouting piles (JGP) prior to excavation to minimize wall deflections and ground settlement, and to prevent basal heave instability. In this paper, finite element analyses were carried out to assess the basal heave factor of safety for excavations in soft clay supported by JGP. Comparison of the factor of safety from the finite element analyses with limit equilibrium methods was then performed. Subsequently, to account for the uncertainties in the soil and JGP properties, a simplified reliability analysis procedure is proposed to estimate the probability of basal heave failure for deep excavations supported by JGP.INTRODUCTIONJet grout piles (JGP) are often used to prevent basal heave instability and to minimize excessive wall and ground movements associated with deep excavations in soft clay deposits (Shirlaw 2003; Wen 2005; Ou 2006). The jet grouting process which is carried out prior to any excavation works produces a series of short overlapping grout columns resulting in a “continuous” base slab (commonly termed as jet grout pile or JGP) below the final excavation level that spans across the entire excavation (Gaba 1990; Hsieh et al. 2003; Ho and Hu 2006). Typically, the JGP thickness ranges from 2 m to 4 m.The focus of this paper is on the assessment of basal heave instability for deep excavations in clay stabilized with JGP. Finite element analyses were first conducted to determine the basal heave factor of safety for deep excavations in clay with JGP. Comparisons were then carried out with factors of safety based on conventional limit equilibrium methods. Since the conventional factor of safety approach does not explicitly reflect the uncertainties of the soil and JGP properties, it is demonstrated in this paper that a simple reliability based approach (Hasofer and Lind 1974) can be used to assess the probability of basal heave failure.LIMIT EQUILIBRIUM METHODFor excavations is clay, the Terzaghi (1943), Bjerrum and Eide (1956) and Eide et al. (1972) methods which are based on bearing capacity theory, are commonly used to determine the basal heave factor of safety. Another commonly adopted method in Japan and Taiwan is the slip circle method which involves taking moments about the lowest strut level (JSA 1988; Hsieh et al. 2008; Luo et al. 2012). The slip circle method has also been applied for excavations with a JGP at the base by incorporating the undrained shear strength of the JGP. In the slip circle method, the basal heave factor of safety FSslip is assessed by taking moments about the lowest strut level (Fig. 1)"

Jan 1, 1900

By Jeremy G. Kress

We propose the discrete element method (DEM) as a complimentary alternative to analytical solutions and FEM models for the analysis of pile response. DEM is a novel approach to the engineering design of deep foundations which can be used to provide insight into the mechanics of soil-soil and soil-structure interaction. It is common to use analytical, empirical, and semi-empirical methods to predict pile behavior, where if granular properties, pile length, or load orientation change, then significant adjustments are made in the design sequence. DEM provides a more uniform approach in granular soils. Based on constitutive force-displacement relationships and laws of motion in rigid and elastic bodies, few changes must be made for a wide variety grain types, pile types, embedment, and load orientation. Preliminary results for simulation of a single pile are qualitatively consistent with results from conventional design procedures and also provide significant information not available from other analyses (e.g., local information about interface failure during shear). Importantly, these analyses are portable to a variety of pile types and installation procedures, which may not be the case for empirical approaches. Given consistent increases in computing power and rapid advances in model speed and sophistication, the DEM should prove to be a robust method for design and the analysis of pile response in granular soils.

Jan 1, 2010

By Tsuyoshi Honda, Kazuhiro Kaneda, Masayuki Imai, Kazuo Konishi, Kunio Higashinaka

"In recent years, the demand for measures to control liquefaction of existing airport runways and harbor structures has increased. However, from the perspectives of constructability and cost, application of grid-form deep mixing walls to these types of structures requires the formation of wider grid spacing as compared with conventional designs. In this research, we focused on the extent of liquefaction and ground surface settling when grid spacing is made wider than conventional designs. We conducted centrifuge model tests, and confirmed the liquefaction suppression effect when grid-form modifications involving wide grid spacing are adopted under asphalt pavement. The tests were conducted under conditions that included changing the grid spacing and groundwater level. When the groundwater level was high, an increase in water pressure was observed, even within the grid. However, when the groundwater level was low, the increase in water pressure inside the grid was suppressed. We also found that if the generation of water pressure can be suppressed, the amount of settling due to liquefaction can also be controlled.INTRODUCTIONOne construction technique used as a countermeasure to liquefaction is grid-form deep mixing walls. Grid-form deep mixing walls are a construction technique for which improved grid-shaped wall bodies are built into the ground below the surface using a deep mixing method. This construction technique minimizes shear deformation by surrounding liquefied ground with improved wall bodies, thereby preventing liquefaction (Fig.1). With conventional designs, grid-form deep mixing walls determine the grid spacing that can deter liquefaction based on a ratio of the grid spacing L to the improved depth H (ratio = L/H). Ordinarily, designs are implemented with an L/H ratio of 0.8 or less (PWRI, 1999).In recent years, a demand for measures to control liquefaction of existing airport pavement and harbor structures has increased. However, when liquefaction countermeasures are implemented at these types of facilities and structures, the construction work must be implemented while the facilities and structures remain in service. Therefore, temporal and spatial constraints must be considered. In addition, unlike conventional liquefaction countermeasures, performance requirements are such that, even if some degree of liquefaction is allowed, the performance is acceptable as long as the amount of settlement is within a predetermined value. Therefore, if grid-form deep mixing walls are applied to these structures, grid spacing that is wider than conventional standards is desired."

Jan 1, 2015

By Walid El Kamash, Sadik Oztoprak

"Soft soil presents a challenge against multistory buildings in some cities of Egypt such as Port Said due to the consolidation settlement. Deep mixed (DM) columns are used to improve the soft foundation soil in order to reduce the total and differential settlements. Latest research revealed that this improvement technique also increases the rate of mechanical consolidation due to column yielding caused by stress concentration from the soft soil. In this study, extended poly-styrene (EPS) Geofoam is used to replace the soft soil over DM columns in order to control the stress concentration and settlement. To understand the effect of EPS geofoam on the degree of consolidation, stress concentration and settlement, a parametric study was carried out through a mechanically and hydraulically-coupled numerical method. A unit cell model is used, in which the soil was considered linear elastic; DM column and EPS Geofoam are elasticplastic materials. Results reveal that EPS geofoam is helpful for reducing the settlements and accelerating the consolidation. Increasing the length of the column of the deep mixed foundation with EPS geofoam has a significant effect on accelerating the consolidation.INTRODUCTIONExpanded polystyrene (EPS) geofoam is a lightweight polymeric material which is made by expansion of raw plastic beads. The expansion of the EPS beads are spherical-shaped particles containing closed hollow cells. EPS which plays an important role as an innovative lightweight construction material is now well recognized due to its low density in addition to high compressive and rupture strength. Inglis (1996) reported the first use of EPS geofoam as a seismic buffer to reduce potential seismic loads against a nonyielding basement wall. Gaskin (2000) and Bathurst et al. (2007) carried out reduced-scale shaking table test on a rigid retaining wall protected by EPS geofoam. The test data showed that the peak lateral loads acting on compressible model walls were reduced below values measured for nominally identical structure but with no compressible inclusion. Abdelrahman and El Kamash (2014) investigated the behavior of EPS Geofoam beneath raft foundation on soft soil of Port Said. They showed the ability of EPS to control vertical displacements. The investigation of the behavior of EPS geofoam with DM column has not attracted more attention of previous researchers. In this paper, the behavior of replacing the soft soil by EPS geofoam was examined in the presence of DM column."

Jan 1, 2015

By Piotr D. Moncarz

As major urban areas begin to run out of "good-terrain" for their expansion, they begin to claim high water-table areas within or adjacent to water fronts or swamps. Similarly, major infrastructure projects encroach on or cross high organic content areas. The associated major structures often require deep foundations located in soils investigated through core samples removed at a discrete number of locations. The investigation is nearly always preoccupied with soil mechanical properties, sometimes with soil non-organic chemistry for concrete and metal corrosion, seldom, if ever, for organic-chemistry and bio-conditions as related to concrete longevity. Not surprisingly so, bio-corrosion of concrete is one of the least understood phenomena by practicing civil engineers. This paper shows how low-iron, organic-rich sediments may trigger sulfate degradation of concrete, even when standard pre-construction chemical analyses indicate only a moderate sulfate level. The discussion is illustrated with a case of a pile foundation in the United States driven into marine channel sediments and sediment-derived fill material. The concrete piles lost their structural integrity due to secondary ettringite formation and depletion of iron in the cement paste. Disintegration of concrete occurred only where it contacted superficial marine sediments and sediment-derived fill material. Concrete in direct contact with seawater or native sand and silt materials appeared to be sound. Sediments in contact with the degraded concrete were highly anoxic and had a history of sewage contamination, contained low concentrations of total iron (<2%), Fe(III) (<0.3%) and moderate levels of sulfate (1500ppm), and exhibited high bacterial activity. This environment resulted in the microbial dissolution of Fe(lll)-rich ferrite in hardened cement paste. Iron depletion in the cement paste had made the concrete vulnerable to degradation by sulfate, even at moderate levels of sulfate concentrations in the sediments.

Jan 1, 2002

By Alain Pecker

The choice of a design concept for a bridge foundation is guided by various factors; several of these factors are indeed of technical origin, like the environmental conditions in a broad sense, but others non technical factors may also have a profound impact on the final design concept. The foundations solutions adopted for the Rion Antirion bridge are described and an attempt is made to pinpoint the major factors that have guided the final choices. The Rion Antirion bridge is exemplar in that respect: the foundation concept combines the simplicity of capacity design, the conceptual facility of construction and enhances the foundation safety. The design of these foundations was a very challenging task which required full cooperation and close interaction with all the parties involved: concessionaire, contractor, designers and design checker.

Jan 1, 2013

By Damir Dedic, Wörle. Patrick

"Soil properties within a construction project area are analyzed during the planning phase. However, it is only possible to achieve selective soil exploration, even in the case of very extensive investigatory programs, which results in a certain soil risk and uncertainties for planning and execution.Therefore, the application of monitoring systems is becoming increasingly important in the field of geotechnics. The application of suitable monitoring systems for these particular purposes provides considerable knowledge relating to the load bearing behavior of the soil and the ground anchor. Applications that present major challenges to measuring anchor forces include back-anchorages of long-lasting and very deep construction pits, construction pits in urban areas, slope and embankment supports for track and vehicular routes, port and lock structures, and uplift control. Apart from overseeing individual construction stages, monitoring systems analyze the interaction between the soil and structure throughout the latter’s entire life cycle and safeguard the functional capability of the applied system components. Geotechnical construction projects can be adapted, optimized and carried out with enhanced safety from the information obtained.Conventional Monitoring SystemsThere are numerous approaches for determining anchor forces of bar or strand anchors. Lift-off tests and measurements with load cells are the most common methods.Lift-off Test: Lift-off tests provide a possibility to monitor the prevailing force in strand or bar anchors. The entire anchor head structure is lifted using the appropriate equipment. The steel tendon is prolonged, or in the case of strand anchors, a screw-on cap holds the wedge carrier so that a tensioning jack can be mounted above it. Then, the tendon is prestressed until the lower anchor nut (bar) or wedge carrier (strand) is lifted off from the anchor plate. The intersection of the two straight lines in the figure represents the force at which the anchor nut or the wedge carrier lifts off from the anchor plate. Thus, the intersection displays the actual load of the anchor. This form of anchor force control gives conclusive results, but at the same time requires extensive accessories and extra personnel to execute the test. For this test, a sufficient bar overhang must be available, the wedge plate must possess an external thread, or there must be a strand overhang of at least 24 in (60 cm). Furthermore, the anchor head must be freely accessible and in a position to be reached with the necessary equipment."

Jan 1, 2017

By Takefumi Takuma, Tsunenobu Nozaki

Light rail transit (LRT) systems have been built in cities all over the world in order to cope with increasing population and heavy car traffic in their downtown cores and surrounding areas. Light rail tracks are often sharing the roadways with automobile traffic while some of them are on the dedicated trackage for safer and faster transit. For example, the twin cities of Minneapolis and St. Paul in the state of Minnesota in the U.S. have their Blue and Green LRT lines in operation with the latter line being extended by 23km to a southwestern suburb of Minneapolis. The mostly dedicated extension alignment includes an 875m long cut-and-cover tunnel because the alignment there is just next to a high-rise condominium complex, a cluster of townhouse buildings, and a parallel running railroad track. Sheet pile walls were selected as part of the earth retaining structures needed for this section of the extension project. The distance between the buildings and the sheet pile alignment is a mere 3m at their closest point. In order to minimize negative impacts to these existing structures from sheet pile installation, press-in piling was utilized. The soil conditions were alternating sand and silt layers with the SPT value varying between 23 and above 50, which necessitated the use of auger attachments. It took two press-in piling machines 14 months to install approximately 2,500 pairs of Z-shaped sheet piles with their lengths between 7.6m and 19.8m. After the sheet pile wall installation, excavation between the walls, installation of internal bracing, and construction of a concrete tunnel box followed. &nbsp;&nbsp;

Oct 7, 2024

By David Sherwood

The paper has been prepared as the basis for the 2008 John Mitchell Memorial Lecture. It reviews major developments in ground engineering over the last 20 years, not from the point of view of technical processes, but from the drivers that have driven these developments and the needs that they have met. It concludes with a glimpse into the future and suggests to where current trends will probably lead us. By its nature such a review is closely aligned with personal experience and it relies heavily on case histories largely from within the writer?s own experience over that period.

Jan 1, 2008

By Sitotaw Y. Fantaye

"The first segment of the Second Avenue Subway extension is approaching construction completion. The new extension will operate along Second Avenue from 96th Street to 63rd Street, where it will divert west along the existing 63rd Street line, stopping at the Lexington Avenue/63rd Street Station. The new line will have stateof-the-art stations at 96th, 86th, 72nd and 63rd streets.Most of the two-track, twin-tunnel subway was constructed using bored tunnel methods (Figure 1), with a tunnel boring machine (TBM). The launch and retrieving box of the TBM was strategically located at the south end of the 96th Street Station where bedrock exists approximately 70 ft (21.3 m) below street level. The TBM launch box and the 96th Street Station (Figure 2), including the ancillary facilities adjacent to the station, were constructed by the cut-and-cover method. The cut-and-cover work required the contractor to design and implement a stiff, tightlybraced retaining wall, approximately 100 ft (30.5 m) long, to tie the existing tunnel constructed in the 1970s to the new station, temporary street decking over the entire excavation, and a wide range of excavation support systems at various locations.The cut-and-cover construction posed significant challenges including: installation of street decking on busy Second Avenue, relocation and suspension of the myriad utilities beneath the streets, and configuration of a lateral support system that would minimize movement of adjacent structures but not slow down excavation activities. This article describes the innovative solutions developed to manage and facilitate safe and efficient construction without disrupting Second Avenue, a major southbound one-way thoroughfare.The work was performed in several phases involving: (1) preconstruction condition survey of existing buildings, (2) installation of instrumentation and monitoring, (3) major utility relocation efforts to move vital utilities from within the alignment of the slurry wall on both the east and west sides of the avenue, (4) implementation of maintenance and protection of traffic plans, (5) installation of temporary street decking across the entire avenue and over the excavation to allow an orderly movement of traffic and pedestrians, (6) staged excavation and installation of an intricate temporary bracing system beneath the decking (7) step-by-step construction of the new subway station’s structure and (8) staged removal of the bracing as the structure gained sufficient strength to resist the lateral loads. The main focus in this article is the design and construction of the temporary street decking and lateral bracing systems; the utility suspension system and the north tie-in that allowed the daunting task of excavation and construction of a new subway station in bustling New York City, with minimal disruption to the community, businesses and everyday traffic."

Jan 1, 2016

By José Carlos A. Cintra

This paper addresses a new experimental procedure to measure the shaft friction and the base resistance of bored piles during static load tests. It is proposed that a set of polystyrene foam discs, placed between the shaft and the base of the pile, be used instead of the usual instrumentation. Throughout the initial stages of the loading test, the foam discs will allow only the mobilization of the shaft friction. The load x settlement curve clearly shows that the shaft friction vanishes at low settlement values. As the load test proceeds, the base resistance is also mobilized. This procedure was used in two belled piles bored at the Experimental Foundation Field of the University of São Paulo, at São Carlos, Brazil. Both piles were 8 m long and had a shaft diameter of 0.6 m. The enlarged base had a diameter of 1.5 m and a height of 0.9 m. Twenty foam discs with a thickness of 20 mm each were placed between the enlarged base and the shaft of the pile. The load tests indicated ultimate shaft frictions of 28 and 30 kPa for measured settlements of 8.98 and 7.39 mm. Base resistance values at failure were 617 and 499 kPa, for a chosen settlement of 10% of the pile base diameter. The proposed approach seems to be straightforward, efficient and inexpensive.

Jan 1, 2002

By Gerald Verbeek

There are certain concepts that seem to invite responses from some, including some in the foundation industry and even some within DFI, that are at best surprising. Business owners and their employees share the desire that their company does well and continues to operate. Maybe company growth is not always realistic but maintaining the current level of activity is in the least what they hope for. In other words, they hope that their company is sustainable, and they are fully behind that notion. But when the concept of sustainability is raised, there is, at least with some, suddenly doubt that that is a good thing. And yet, that concept only aims to achieve at a grander scale what the owners and employees desire for their company. There are many definitions of the term sustainability, but probably the most commonly used description is that framed by the United Nations in 1987. It states that sustainability is the concept of meeting the needs of the present without compromising the ability of future generations to meet their own needs. Arguably that definition is too abstract and does not provide the type of specific goals and targets we are used to. To help with that, to some extent, in 2015 the United Nations formulated 17 Sustainable Development Goals (SDGs), to provide "a shared blueprint for peace and prosperity for people and the planet, now and into the future." And undoubtedly those SDGs are fodder for those that question the concept of sustainability in the foundation industry. How can our industry, they wonder, ensure that there is no poverty or hunger (SDG 1 and 2), and the climate action goal (SDG 13) immediately leads to the hot button topic of global warming. And maybe this is where advocates lose (some of) the sceptics of the sustainability concept, but hopefully they will continue to read this article that lays out why sustainability simply makes sense, also for the foundation industry and especially for DFI.

Nov 1, 2022

By Mario Mauro

Tuttle Creek Dam was constructed by the U.S. Army Corps of Engineers in the 1950?s on the Big Blue River in north-east Kansas. Since the dam is located in a seismic area, the safety of the dam was re-evaluated under the national U.S. Army Corps of Engineers Dam Safety and Assurance Program. After a series of studies and analyses performed by the Kansas City District of the U.S. Army Corps of Engineers, in 2003 the Department of the Army authorized the implementation of the plan ?Stabilize Foundation Soil without Drawdown Alternative?, during a 7-10 year construction period. As part of this plan, in 2006 Treviicos South carried out a large scale jet grouting and deep mixing test program downstream the dam. The test program included the installation of twenty-seven double and triple-fluid jet grout columns and twenty-seven jet-assisted deep mix columns. The jet grout columns were constructed at different levels of specific energy and cement content. The deep mix columns ranged in diameter between 3 ft and 6 ft. During column placement, the drilling and grouting parameters, pore pressures, and soil movements were instrumented in real-time. The downstream test area was enclosed by a cement-bentonite wall extended to bedrock, which allowed a 35-ft deep open excavation around the 45-ft deep columns. The exposed jet grout columns measured up to 15 ft in diameter, exceeding the anticipated target diameter. In addition to coring, some of the jet grout and soil mix test columns were saw-cut along the group axis, providing useful information on the internal column structure.

Jan 1, 2008

By X. M. Wu

The paper describes four different types of support for deep excavations, which are currently used in China. Local experiences were illustrated by presenting case histories for each type of support. For braced excavation in soft clays in Shanghai, the earth pressure against bracings were found to be in conformity with the trapizoidal estimation given by Terzaghi and Peck (1967). For tie-back support of excavations in Beijing and Shengyang, earth pressures were found to be much less than those predicted by ordinary rules. In the construction of a mining shaft in coarse sand below ground water level, high pressure jet grouting has been successfully used to form a circular impervious lining of the shaft. As an effective anti-slide measure, large diameter reinforced concrete piles constructed by open shaft method have been widely used with success.

Jan 1, 2010

By Wolfram Groh

New underground floors comprising the complete footprint area of the building structure, were constructed under an existing building in sand, located in the Verdun district of Beirut / Lebanon. The works for the rehabilitation and extension of the Verdun 528 building were carried out between December 1999 and August 2000. A restriction of differential vertical movement of existing load bearing walls and columns had to be respected throughout the construction phase of the new basements. Support measures for the building were taken based on a underpinning system with Bauer SVV preloaded micropiles. The specialty of this underpinning job was that the building loads at the time of preloading and excavation of new basements was substantially less than at final stage. The design of the preloading system was particularly challenging in view of the transition from temporary to final load transfer under variable load conditions. Load transfer was based on the Bauer SVV micropile head system applied in several technical variants. Monitoring of levels of structural elements performed throughout the construction works confirmed that the differential movements of adjacent load bearing columns and walls were maintained within the specified limits.

Jan 1, 2002

By J. G. La Fonta

The rapid development of real-time monitoring technology for the construction of large underground structures in urban areas can be attributed to: the zero-risk objective, the need for transparency between all parties involved and the control of real cost within the budget. Real-time monitoring can be an integral part of the construction contract (for example when compensation grouting is required) or independent, in particular when measurements of existing structures and buildings bordering the project are to be taken before construction starts. Three examples of extensive field instrumentation schemes are described: a large road tunnel in the Moscow suburbs, a new metro line in Amsterdam and major redevelopment works at a busy Central London rail interchange.

Jan 1, 2006