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By Vishal Pathak, Shailesh A. Godhuly

Ground Modification System in terms of Jet Grouting for soil strengthening and mass stabilization was engaged for a power plant project in an international power project, engineered by L&T-S&L. The site Geology consist of cohesionless type of sandy alluvial deposits (silty fine sand) as the main formation. Ground water table is encountered at shallow depth. Geological interpretation is done using soil investigation data along with CPT’s. This paper discusses design and implementation of jet grout technique to improve the mechanical behaviour of soil. To distribute load evenly from superstructure, a layer of growmast (drainage blanket) is laid above jet grout columns. Settlement evaluation is done using Finite element analysis with Plaxis 2D and Settle 3D. In the project, selected equipment foundations are resting on jet-grout columns including vibratory equipment like 144MW Gas Turbine etc. The project has been commissioned in September 2021 and operating with full capacity.

Sep 1, 2022

By Rüdiger Wunsch

The new high speed Vienna - St.Pölten line and the Lainzer tunnel are to be connected to the existing Western railway line in Vienna. This involves building an underground cut and cover branching tunnel which will be connected to the Western railway line by ramps. A key structure is the Herzmansky Street tunnel, which has a length of some 820m. It is to be constructed as a cut and cover tunnel using the top down method. The walls of the tunnel are designed as a water resistant structure consisting of double walls, an outer wall of bored piles and an inner reinforced concrete wall. The bored pile wall will be used as a temporary retaining wall during the construction phase and will also be a structural part of the per­manent tunnel wall. The retaining walls of the open pit, which will have a depth of up to 14m and a width of 12m, were investigated as a non-contiguous bored pile wall and overlapped bored pile wall. Preventing ground water from penetrating into the pit is of paramount importance. The high ground wa­ter level is the determining factor for the dimensioning of the bored pile wall and results in the require­ment for a water resistant concrete structure. It has been necessary to adopt adequate measures, therefore, in order to reduce the hydrostatic water pressure during the construction phase, assuming economical pile dimensions.

Jan 1, 2000

By Luo Yang

A one-dimensional wave equation based algorithm for estimation of shaft and toe resistance of driven piles using High Strain Testing (HST) data is presented. The pile is represented by a uniform elastic bar, while the soil around the pile is assumed as a homogenized isotropic medium, and Smith model is adopted to represent soil-pile interaction in the wave equation analysis. In most cases, the displacement of pile particles along pile shaft is greater than recoverable soil deformation (i.e., soil quake in Smith model). Therefore, static shaft resistance could be reasonably assumed to be totally mobilized during pile driving. Smith damping factor is used to account for combined dynamic and rate effect. Force and velocity time histories measured at the pile head are used as input boundary conditions in an analytical solution of the one-dimensional wave equation. As a result, two unknown parameters, static shaft resistance and Smith damping factor, can be incorporated into the one-dimensional wave equation and determined analytically for the time duration prior to the first downward wave reaching the pile toe. Then, soil resistance and Smith damping factor at pile toe can be further determined. The advantage of the proposed analysis technique is that the Smith damping factor and the static soil resistance can be directly determined based on the closed-form solution of the one-dimensional wave equation, which is computationally efficient. Numerical examples are given to illustrate the use of the proposed method to determine the pertinent Smith model constants and the static resistances.

Jan 1, 2006

By Dileej M. Dewaikar, Poonam A. Patil

"In this paper, the ultimate lateral resistance of a long, flexible, unrestrained vertical pile in a cohesive soil is computed under static loading condition using py curves. A simple and improved method for the construction of hyperbolic p-y curves for a cohesive soil is proposed for static loading conditions. An iterative analysis is employed with secant modulus approach, using a matrix method known as moment area method developed by Sawant and Dewaikar. The loadground line displacement relationship is obtained for different load eccentricities using p-y curves developed by Matlock, Georgiadis et al. and the proposed hyperbolic p-y curves for different eccentricity ratios. These values are compared with the values computed from model test performed by Rao et al. and with the limit equilibrium solution given by Broms. The comparison shows that, the results obtained using hyperbolic p-y curves shows a better agreement with the model test data with the maximum difference within 15% using other methods; whereas Broms' limit equilibrium solution shows some agreement with the results based on Matlock's p-y curves.INTRODUCTIONPile foundations are used for jacket type offshore structures, which are subjected to large magnitudes of lateral loads due to lake or ocean waves, winds and ice forces. The failure of a pile-soil system is catastrophic and excessive deflection of the pile creates operational difficulties. In the view of this, bending moment in the pile is required to be predicted in a rationar manner. The p-y concept developed by Reese and Matlock (1956) is popularly being used to estimate the pile top deflection and bending moments.The ultimate lateral load which causes collapse of a pile-soil system is generally estimated using Broms' (1964) method, which is based on limit equilibrium considerations. The p-y curves are basically nonlinear in nature and include ultimate pressure at the depth where they are generated. Therefore, if the lateral deflection of pile top against different magnitudes of lateral load is obtained, it should be possible to obtain the ultimate lateral load from this load-deflection relationship."

Jan 1, 2005

By Michael Hughes, Selva Selvamohan, Ray Costa

"Cutoff walls are commonly used to mitigate underseepage problems for levee remediation projects. At abrupt changes in seepage cutoff wall depths there is a potential for water to flow around the back of the deeper cutoff wall leading to elevated seepage pressures on the landside that could result in exit gradients exceeding design criteria. This condition is referred to as end-around-effects and is a complex problem that requires detailed and time consuming 3-D numerical modeling to represent accurately. This paper presents a simple approach for assessing end-around-effects using the results of 2- D seepage analysis to determine if lateral extension of the deeper portion of the cutoff wall is required. This simplified approach provides a pragmatic solution to a complex 3-D problem. The presented procedure was used as part of the Feather River West Levee Project in Yuba City, California, to assess end-around-effects at 26 locations. The results showed that wall extensions of up to 100 feet were needed at only 2 locations.INTRODUCTIONAs the lead geotechnical consultant for the Feather River West Levee Project, AECOM were responsible for designing levee remediation works for approximately 35 miles of levee protecting the area around Yuba City, California, and communities to the north and south. Due to land use constraints, seepage cutoff walls were the main remediation alternative selected to address underseepage issues for the project.As part of the design review process, the California Department of Water Resources (DWR) requested AECOM to look at 26 locations along the levee alignment where the depth of cutoff wall changed abruptly from shallow to deep, or vice versa. At these locations there was the potential for seepage pressures to pass behind the deeper section of cutoff wall and stress the blanket layer landward of the cutoff wall. A condition referred to as end-around-effects.End-around-effects involve complex 3-D ground conditions that have traditionally been addressed by laterally extending the deeper section of cutoff wall an arbitrary distance based solely on engineering judgment. In discussions with DWR, AECOM developed a simple procedure to provide a more objective assessment of end-around-effects without the need for detailed and time consuming analysis. This procedure allows the engineer to make an informed decision of whether end-around-effects are a problem at the location of a cutoff wall transition rather than laterally extending the deeper section of cutoff wall an arbitrary distance based on engineering judgment alone."

Jan 1, 2015

By Satyajit Vaidya, Rudolph Frizzi, Quadri Owokoniran

"This paper presents a case history in the design and construction of high-capacity drilled shafts for the iconic New York Wheel presently being constructed along the St. George area waterfront in northern Staten Island, New York. Although the site is located in an area that offers views of the Statue of Liberty, the Manhattan skyline, and New York Harbor, the variable and challenging subsurface conditions at the site and the structural loading requirements for Wheel erection and service conditions presented geotechnical design and construction challenges. The paper focuses on site and subsurface conditions, drilled shaft design and construction details, results of Osterberg-cell and lateral load testing, and load test data analysis and evaluation.PROJECT DESCRIPTIONThe proposed 630-foot (190 m) -tall New York Wheel (the Wheel) is projected to be one of the tallest observation wheels in the world. Upon completion, the Wheel will be capable of carrying over 1,400 passengers in its 36 capsules. The Wheel site is located along New York Harbor offering views of the Statue of Liberty, the Manhattan skyline, and the New York Harbor; see Fig. 1. The Wheel structure is sited along the waterfront, and served by a 3-story terminal located south of the Wheel in the eastern portion of the site and having a footprint area of about 34,250 sq-ft (3,180 sq-m). A 4-story parking Garage, with a footprint of about 112,840 sq-ft (10,480 sqm), is to be constructed south of the Wheel in the central and western portions of the site.SITE AND SUBSURFACE CONDITIONSThe site’s close proximity to the New York Harbor presented geotechnical challenges because the site is located in an area that was once beyond the historic shoreline of Staten Island. The site is an about 350,000-sq-ft (32,500-sq-m) parcel generally bounded by the Richmond County Bank Ballpark to the southeast, the 9-11 Memorial to the east, Bank Street to the north and northeast, and Richmond Terrace and an associated retaining wall to the southwest and south. A 50-ft (15-m) -wide New York City Transit Easement, with an active on-grade service area and tracks, is located in the southern portion of the site. See Fig. 2 for site location and approximate location of the Wheel foundation footprint."

Jan 1, 2016

By Onur Guvener, Kalaiarasi Vembu, C. Vipulanandan

"Installation procedure and the quality of the material used in the construction have significant effects on the behavior of the Auger Cast in Place (ACIP) piles. In this study, Installation and curing of a 760 mm (30 in.) diameter and 12 m (39 ft) long ACIP pile with a design capacity of 1140 kN (128 tons) in hard clay was investigated. Construction quality was monitored using the automated monitoring system where the volume of grout pumped and the pressures were monitored with depth. The curing of the pile was monitored using axial vibrating wire strain gages at four levels and lateral vibrating wire strain gages at two levels. The residual strain and temperature profile in the curing pile was monitored over a period of week to determine the appropriate time for load testing the pile. Axial behavior of Auger Cast in Place (ACIP) Piles in hard clay was studied using full scale load test on an instrumented pile. The load-settlement and load transfer relationships of the pile was investigated based on the load test results. Development of skin friction in the load test pile and the reaction pile was also investigated.INTRODUCTIONAugered cast-in-place piles (ACIP) are drilled foundation installed by drilling a hole with a continuous flight auger to a predetermined depth. Non-displacement Augered Cast-in-Place (ACIP) piles are increasingly used for supporting building, bridges, sound barrier walls and many other structures around the world. In an ACIP pile, depending on the soil type and rate of the auger advance, ground stresses are maintained near the value that existed before construction by using a continuous flight auger, which is never withdrawn until the cementitious material (fluid Portland cement grout) is placed by pumping the grout beneath the withdrawing auger under pressure through the hollow stem of the auger (Vipulanandan, 2005). ACIP piles are typically installed with diameters ranging from 0.3 to 1.0 m and lengths up to 30 m (Brown, 2005) although longer lengths have occasionally been installed. Comparing to the drilled shafts and driven piles of equivalent size ACIP piles can be installed more rapidly with fewer disturbances to the surroundings in favorable geological conditions. Hence the installation procedure and the quality of material used in the construction have significant effects on the behavior of ACIP piles (Vipulanandan, et al. 2007). In this paper construction quality control technique for ACIP piles was investigated. Load displacement and load transfer behavior of pile in compression and tension in hard clay was also studied. The development of side resistance in compression and tension for the load test piles and the reaction pile were also investigated."

Jan 1, 2017

By Dan Brown

A method is outlined for computing the contribution of a micropile group to global stability of a sliding mass. The forces in the micropile are computed in a way which accounts for the effect of soil mass movement on the mobilization of axial and shear forces and which maintains compatibility between shear and axial force as a function of displacement. The method provides a rigorous model to incorporate the pile forces into the stability calculations, including the effect of pile forces on the resultant shear and normal forces at the sliding surface. This paper demonstrates the proposed solution using a simple example slope.

Jan 1, 2007

By T. J. Snell

Bolnore Village in Haywards Heath, Sussex, England, is a large development covering 8 to 10 hectares and expected to provide 1500 homes in five phases to assist in the continuing demand for new homes in the London area. Part of the development required housing on a relatively shallow slope found to have deep seated failure planes which are fairly prevalent in this part of Sussex. Locally the slope angle was around 20 degrees but more typically the gradient was 6 to 7 degrees. There were significant concerns about slope stability and bearing capacity due to pre-existing shear surfaces and the complex geotechnical profile. There was some evidence of instability in the form of residual shear surfaces and tension cracks. The development required terracing the site with retaining structures up to 5 meters in height, formation of access roads and foundations of new houses. The developer Crest Nicholson adopted a collaborative approach with consulting engineers Powell Tolner and specialist geotechnical contractor Keller Ground Engineering. The solution consisted of a novel combination of contiguous bored piling, ground anchors, and both block work and timbacrib retaining walls to ensure the geotechnical issues were adequately addressed within the time and cost constraints set by the team. The paper describes the geotechnics of the problem together with the design, practical implementation, and site progress achieved

Jan 1, 2006

By Aly M. Mohammad

The 12th and 14th Street Viaducts, which carry Route 139, are located west of the Holland Tunnel in Jersey City, New Jersey. The two viaducts, provide access to and from the Holland Tunnel (which connects New York City and New Jersey) and carry upwards of 50,0000 vehicles per day from Jersey City and New York City to points west. The New Jersey Department of Transportation (NJDOT) selected AECOM to perform design services including rehabilitation and seismic retrofit for the 12th Street and 14th Street Viaducts while maintaining traffic at all times. Building a new parallel bridge just north of the 14th Street Viaduct was essential in avoiding extremely costly traffic delays. Installation of the new foundation, in close proximity to the existing viaduct, required drilling through some of the existing timber piles supporting the bridge. As a result, the existing bridge was required to be reanalyzed for this new foundation configuration. This proposed structure consisted of 8 piers each supported on a single six (6) foot diameter drilled shaft. Currently this portion of the bridge structure has been constructed. The shafts were constructed with rock sockets that were five feet six inches (5?- 6??) in diameter and were extended 11.2 feet (3.4 meters) into rock. A 2300 ton Osterberg Load Test was performed on one production shaft to confirm the capacity of the shaft. The rock socket for the test shaft was in sandstone. This paper will present a description of the design methodology and construction methods adopted for the foundations. In addition, the paper will illustrate the Osterberg Load Test including: equipment used, number and locations of strain gages, and interpretation of results. Additionally, regarding the close proximity of the new foundation, the paper will present the type of equipment used to drill through the existing timber pile foundation while minimizing the impact on the integrity of the existing foundation. We will also present the method of analysis for analyzing the redistribution of load on the remaining piles. The results presented in this paper will assist the design engineer by providing a comparison between the geotechnical design assumptions and the actual measurements obtained by field measurements for this rock formation.

Jan 1, 2009

By Alexander Filotti, Stanley Merjan

"Abstract. The paper shows the benefits and accomplishments of this relatively new but established product on the pile foundations market in the United States. The first part of the paper describes general aspects of the design, construction, and geotechnical capacity (designed and in situ) of Tapertube piles. The qualities resulting from the design and manufacturing of the Tapertube pile will be presented first.The second part of the paper describes the installation of Tapertube piles for an addition to Terminal One at JFK International Airport and The Edge development. A carbon print analysis for both projects is developed using the EFFC-DFI carbon print calculator. For the JFK project the benefits of using BIM in redesigning the project for Tapertube piles are explored.General description.The tapertube pile consists of a tapered tubular bottom section attached to a conventional pipe extension. The 50 ksi steel for the taper is mechanically folded into a polygonal cross-section (usually 12-sided) with a longitudinal welded seam. The tapers are fabricated in many sizes with bottom diameters varying from 8 to 14 inches, top diameters from 12 to 20 inches, lengths from 10 to 35 feet, and steel thicknesses from 3/16 to 1/2 inch. A conical steel shoe or a flat plate is welded to the bottom of the taper and the top of the taper is circularized to match the outside diameter of the pipe extension. The inclination of the tapers is generally between 1.5% and 2.5%.The pipe extension is fully butt welded to the taper and has the necessary length for the pile to develop the requisite capacity. Concrete fill for the piles is generally 4,000 p.s.i. or more. Typically the piles are shopassembled and shipped to jobsites in lengths to 80 feet."

Jan 1, 2014

By Gary Kuhns

Central Florida is among the fastest growing urban areas in the United States, and its rapid development has required the steady construction of various types of civil engineering works. The karst geologic terrain and variable geotechnical conditions, however, present special challenges to the design and construction of deep foundations. The subsurface profile can be idealized as a surficial layer of Pleistocene sands, underlain by the highly variable Miocene-age Hawthorn Group, consisting of various combinations of sand, silt, clay, phosphate and highly weathered limestone. The Hawthorn Group is underlain by Eocene-age limestone that comprises the Floridan aquifer. Vast networks of solution cavities are present throughout the Eocene limestone, sometimes allowing downward raveling of the overlying soils and the creation of sinkholes. In some cases, the relic sinkholes can be filled with soft compressible organic soils extending to depths greater than 100 feet (30.5 m). Driven piles are frequently employed as a deep foundation alternative, although occasionally cast-in-place piles/shafts have also been used. Piles are often driven for bearing in the weathered limestone within the Hawthorn Group, but are sometimes installed as friction piles in the upper soil and intermediate geomaterials. Dynamic pile testing is routinely performed during pre-construction test pile programs, or during production for quality control and assurance purposes. This paper presents discussions on the design and construction aspects of deep foundations unique to Central Florida subsurface conditions and local practice. Foundation issues such as subsurface variability, soil setup, pile damage, negative skin friction, and sinkhole conditions are discussed with the aid of demonstrative case histories.

Jan 1, 2003

By George Filz, Morales, Carlos, Bertero, Filippo Maria, Alessandro, Leoni

"The Deep Mixing Method (DMM) represents a viable solution to improve adverse geotechnical properties of foundation soils for many practical applications. A pre-construction soil investigation campaign is necessary to assess soil properties and to retrieve samples of different soil layers for a laboratory Bench Scale Testing program (BST). The BST has to be designed using various binder types, binder contents, and water/cement ratios in each of the soil types. Following the laboratory program, a full scale Field Test (FT) is typically necessary to verify the results of the BST. This paper will highlight the differences and the importance of performing both pre-construction laboratory tests and field tests to ascertain the proper mixing parameters in the different soil layers. Comparative analyses and interpretations between the lab and field stages, along with accumulated information about soil properties and quality control (QC) results, allow fine-tuning the production parameters throughout a project. Three Deep Mixing Method projects, where both laboratory and field tests were executed, are illustrated: (1) The LPV 111 Project (New Orleans, LA, USA): DMM was used for ground improvement/foundation strengthening to stabilize and support the burden of a new levee raise; (2) The Rio Puerto Nuevo Project (San Juan, PR, USA): DMM was applied to improve the soils adjacent to a 90"" forced sewer main relocation and to improve the soils for the base of a new drainage channel; and (3) State Road 83 (US 331) over Choctawhatchee Bay project (Walton County, FL, USA): DMM was applied to stabilize the causeway sections of the bridge enhancement project. Data recorded during laboratory and field tests for these projects were analyzed and interpreted to select the most appropriate construction parameters to provide a final high-quality product.INTRODUCTIONThe Deep Mixing Method (DMM) represents a viable solution to improve adverse geotechnical properties of foundation soils in many situations. The effectiveness of working parameters depends largely on the physical and mechanical properties of the soil to be treated. Therefore, well designed laboratory and field test programs, aimed to disclose the interaction between the site-specific soils and the mixing parameters, are essential to achieve the desired end product.Generally a pre-construction soil investigation campaign has to be performed to assess soil properties and to retrieve samples of different soil layers for the laboratory Bench Scale Testing programme (BST). The BST has to be designed using various binder types, binder contents (or cement factors - CF), and grout water/cement ratios (W/C) in each of the soil types; the selection of the different combinations and dosages for the BST is based on past extensive experiences on similar materials. Following the laboratory programme results, a full scale Field Test (FT) has to be designed and executed, installing several DMM elements to verify the results of the BST and fine tune the construction parameters, with the appropriate binder type and dosage and the most effective equipment and tool configuration."

Jan 1, 2015

By Nuno Cruz, Saúl Rodríguez

"When executing offshore bored piles there are several specific factors and problems to consider in order to guarantee excavation stability. One of the methods employed to carry out this type of work consists in setting up a floating work platform, typically a barge, and implementing a soil stabilization system that combines a partial steel guiding casing with third generation polymeric drilling fluids. The main aspects to take into consideration when performing offshore pile boring works are soil stabilization, project design, work methodology and operational aspects. An example of a work methodology problem arises before any pile boring work takes place as the steel guiding casing contains water, sometimes salt water. What to do with this water in order to replace it by an adequate polymer fluid will determine the stabilization capacity as soon as the shaft advances below the protection of the casing. Another example of operational problem may derive from barge movements while executing boring activities. This study is the result of extensive field data collection and concrete logging analysis from marine projects using polymers in different continents. The bored pile stability target was set ranging between 2% to 15% of concrete overbreak. Values above 15% or below 2% mean that there is a stability problem. Then the off-target pile’s data is collected, analyzed and classified under categories. Thus, a direct correlation is established between the problem category and the final results. Modifying steps in the pre-established construction methods or operational variables guarantees target results without the need to replace the approved construction methods. As a general conclusion, the worldwide experience in large diameter marine works, allows to provide truthful information and solutions for these problems. In knowing how to follow a logical sequence of work and applying adequate work methodology will be the key for success.GENERALBackgroundTo carry out the drilling process of offshore bored piles there are two main options to take into consideration: drilling the pile by using full guiding casing until final depth; or using a combined system of partial steel guiding casing and support drilling fluids.The knowledge and situations described in this paper come from the experience acquired in different projects where the second method was employed. This construction method consists in installing a steel guiding casing by vibration and thus covering the water table and further stabilizing the soil below it with polymeric fluids until reaching the pile’s final depth. The Fig. 1 schematic shows an example of this method where H corresponds to the length of the steel guiding casing whereas the remainder of the shaft’s length is stabilized by polymer fluid. The entire bored length is full of slurry up to top of casing.In most cases this kind of civil works results from the need to build a bridge or executing port structures in places where the creation of temporary artificial peninsulas with fill material is impracticable or not allowed. Hence the need to use floating work platforms, commonly referred to as barges."

Jan 1, 2017

By Ke Yang, Robert Liang

"Drilled shaft foundations are widely used for many types of structures, especially for highway bridges, high rise buildings, and costal structures. The lateral design considerations are crucial for those structures that are subjected to lateral thrust forces, winds, waves, and earthquakes. The p-y analysis is the most widely used method for the analysis and design of drilled shafts for lateral load applications in soils. However, existing p-y criteria were developed based on the lateral load tests on small diameter drilled shafts in soils. Although, a lot of lateral load tests have been conducted, there are a limited number of lateral load tests on large diameter drilled shafts embedded in clay. In this paper, a lateral load test on 2.44 m diameter fully instrumented drilled shafts in clay is presented. The site specific p-y curves are derived based on strain gage readings. The existing p-y curves are found to be much softer than the site specific p-y curves. Correspondingly, the deflection at the top of the test shaft under the maximum applied load is predicted to be eight times larger than the measured value using existing p-y criteria. A new p-y criterion is proposed in this paper. The proposed p-y criterion is proven to be able to capture the site specific p-y curves of the load test and to predict closely the deflections at the top of the test shaft. INTRODUCTIONDrilled shaft foundations are widely used for many types of structures, especially for highway bridges and costal structures. The lateral design considerations are crucial for those structures that are subjected to lateral thrust forces, winds, waves, and earthquakes. Although efforts have been made on studying lateral response of drilled shafts; nevertheless, only limited studies have been published on the behavior of large diameter drilled shafts under lateral loads and the corresponding design methods."

Jan 1, 2005

By Anthony H. Tawil

Modern, high-speed machines used in the manufacture of paper require foundations with stringent settlement constraints. To fulfill this requirement, caisson piles, extending into bedrock, were selected to support a paper machine in Baie Comeau for the Quebec North Shore Paper Company (QNSPCo.). This was the fourth machine in an existing paper mill, and its construction was part of an expansion program which included the building of associated structures such as a wood room and chip storage building, and other facilities, Figure 1. The paper mill in Baie Comeau, Quebec, is located in an area which has extensive deposits of sensitive marine clay which are transformed into a viscous liquid when disturbed by external forces such as the driving of piles. Loss of ground and soil disturbance as affected by piling activity assumed considerable importance in the design and construction of the caissons particularly in view of the proximity of existing plant facilities, including another paper machine.

Jan 1, 1987

By Patrick E. Durnal

A joint venture of Ben C. Gerwick Inc., Sverdrup (now Jacobs) and DMJM (now DMJM Harris) designed the $779 mill seismic upgrade of the Richmond - San Rafael Bridge over the San Pablo Bay in the San Francisco Bay Area and provided construction support to Caltrans. Construction of the marine foundation retrofit was completed by a joint venture of Tudor Saliba/Tidewater/Koch-Skanska and their subcontractors: Pomeroy Precast Construction, AGRA Foundations, Dutra Construction and Vortex Divers. Construction management and inspection was performed by Caltrans with support of various consultants.

Jan 1, 2013

By Paolo Heiniger

The aim of this paper is to present the operative solutions devised and then adopted to implement the underexcavation (soil extraction) of the Tower of Pisa, by means of soil extraction. The intervention has been performed by the Consorzio Progetto Torre di Pisa, a joint venture made of five qualified Italian companies (Trevi S.p.A. , Rodio S.p.A., Italsonda S.p.A., Ismes -Enel Hydro S.p.A., Bonifica S.p.A.), selected for their experience in the field of monitoring and restoration of monuments, structural design, foundation engineering and specialised works in underground conditions. Since 1991 the Consorzio has been charged with the specific task of implementing, within the contractual frame of a Concession, all the decisions made by the International Multidisciplinary Commission appointed by the Italian Government the previous year, with the aim at solving the «problem» of the Tower, strengthening the structure and stabilising its foundation. The Trevi Group, which is represented by Trevi S.p.A. in the above mentioned Consorzio, has given and is giving its direct and constant contribution and is engaged in supplying the special equipment to the operation and the drilling technology which has been successfully adopted to date.

Jan 1, 2000

By Zachary Q. Maassen

The purpose of this paper is to highlight the environmental benefits of properly managing slurry waste as it is generated on site. The following projects will be used to illustrate the importance of proper onsite waste management. Project: Jet Grout Backflow Dewatering The goal was to dewater the backflow directly onsite to produce a dry, solid waste and reusable water. The backflow spoil was pumped directly to the dewatering system as it was generated. Utilizing mechanical separation equipment and flocculation polymer the waste volume was reduced by 44%. Due to the site footprint and high volumes, slurry waste removal and onsite processing were the only two feasible options. Onsite dewatering proved to be the environmentally beneficial option as it eliminated the need for slurry waste hauling and disposal. The benefits of utilizing a dewatering system are listed below: Project: Soil Mixing Spoil Recycling for Slurry Wall Construction In this application the spoils generated contain bentonite mud, cement mixture and organic ground soils. The goal of this project was to process the backflow mixture to recover reusable bentonite mud and separate the soil as a dry, stackable waste product. The treatment system replaced the traditional method of vacuum truck extraction and facility disposal. The environmental benefits of properly handling the backflow is a decrease in fresh water usage, bentonite additive reduction, and the reduction of CO2 emissions. The paper will consist of a project scope, technical equipment and process description, environmental impact reduction calculations and lessons learned for each project.

Jan 1, 2018

By Emre Biringen

Over the past decades, there has been an increasing recognition of the strategic use of pile-supported rafts in design of heavily-loaded structures to reduce total and differential settlements. However, such a hybrid foundation construction method has not been widely utilized in many countries, including the U.S., due to code limitations. In current practice, the foundation design is based on either (i) the bearing capacity of the raft supported by the subgrade soils, or (ii) solely the pile capacity. This paper addresses the potential use of such hybrid piled-raft systems, where the structural load is shared by both by the piles and the subgrade soils directly beneath the raft, in foundation design of power plant structures. The study assessed some of the characteristics of piled-raft behavior by undertaking three-dimensional finite element analyses of two raft sizes, and various pile layout patterns, including the rafts with piles distributed evenly and only in the central area of the raft. The computer software PLAXIS 3D with the Mohr-Coulomb constitutive soil model was used to facilitate the modeling of such cases. The results presented in this paper indicate how strategically locating the piles could reduce the differential and total settlements.