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By P. Seethalakshmi, Yatakuri Yaswanth Naidu

The use of a single pile, group of piles with pile cap, piled raft foundation system, etc., are prevalent in transferring the superstructure load from the soft soil layers to the firm underground layers to reduce the settlement and improve the bearing capacity. The recent development of disconnected piled raft foundation has gained greater importance in improving the load transfer mechanism among the pile, raft, and subsoil by reducing the vulnerability of the greatest axial force on the pile head which leads to pile failure. The present study aims at analyzing the performance of unreinforced and Geogrid reinforced disconnected piled raft foundations under vertical loading using the commercially available finite element software PLAXIS-3D. A parametric study was conducted on unreinforced and reinforced disconnected piled raft foundations to explore the effect of varying pile stiffness as well as the inclusion of Geogrid layer on the load vs settlement, the load sharing ratio of piles and raft, and the distribution of axial load and bending moment along the length of the pile. The Mohr-Coulomb model was used for the granular cushion layer while the Modified Cam Clay model was used for soft clay underlain the sand layer. Raft and piles were assumed to be rigid and linear elastic. The results showed that axial force taken by piles with higher stiffness was maximum while settlement at the bottom tip of the pile with higher stiffness was maximum in both reinforced as well as unreinforced disconnected piled raft systems.

Sep 1, 2022

By Unnikrishnan Nair, Sandeep S. Nikam, Sanjay D. Patil, Prabir C. Basu

"Mumbai Metropolitan Region Development Authority (MMRDA) entrusted to implement Monorail Systems in various parts of Mumbai Metropolitan Region (MMR) with the objective to supplement the present transport system in MMR. The stretch of Monorail is starting from Sant Gadge Maharaj Chowk (SGMC) and extending up to Chembur Railway Station, divided into 2 phases. Construction of Phase 1 (Chembur to Wadala Depot) is complete and Phase 2 (Wadala Depot to SGMC) is under construction.Monorail runs on prestressed girder (guide beam) of span ranging from 20m to 28m supported on pier founded upon group of end bearing piles embedded in rock, pile group ranging from 2-4 piles of diameter 1000mm each.For the purpose of site characterization, geo-technical investigations were carried out along the alignment of Monorail system as mentioned above. These investigations included field and laboratory tests. The subsurface strata mainly consist of silty sand, gravel, underlain by marine clay extending up to stronger basalt rock with volcanic breccia. Overburden consisting of mainly marine clay ranging from 5.5m to 11m at all locations within the influence zone of settlement.The existing rigid pavement along of Sion-Koliwada and Anik-Wadala were constructed about 5 years prior to the construction of Monorail piers. Before laying the rigid pavement, to improve the geotechnical strength of subsoil (mainly marine clay), ground improvement using stone columns was undertaken by MMRDA. In light of limited right of way, the Monorail piers have been constructed in the median portion of the road. The line became operational on February 2014, in few months it was noticed that, in the vicinity of the Monorail piers, along Sion-Koliwada link and Anik-Wadala link, the Road Pavement Quality Concrete (PQC) panels adjacent to the Monorail piers started showing distress in form of nonuniform settlement of the concrete panels.Effect of pile foundation on pavements/PQC slab distress and possible causes of distress were investigated. Initially the distress was thought to be upheaval of monorail pier cap, but further investigations revealed the same to be soil settlement occurring over time. This paper describes the investigation carried out for identifying the cause of this settlement."

Jan 1, 2015

By Brandon T. Buschmeier, Sonia S. Swift, Michael P. Walker, Frederic Masse

"Ground improvement has undoubtedly become a cost-efficient and effective solution to support the development of poor soil sites. Ground improvement elements, such as Controlled Modulus Columns (CMCs), replace piles by improving the subsurface soils and reducing settlement. As ground improvement becomes more popular, the applications become more creative and ground improvement is being used to control settlements under large structures with tight settlement tolerances.In this paper, we will discuss the use of CMCs to support two (2) large industrial warehouses where soil conditions would normally lead to the use of deep foundations and a structural slab, grade beams, and hung utilities to prevent excess settlement. Each of the sites we will discuss had poor soil conditions in the form of very soft or compressible soil, heterogeneous fill of varying thickness, and environmental contamination. At each site, we developed a design that would allow for the use of Controlled Modulus Columns (CMCs) with a Load Transfer Platform (LTP) in place of the previously-proposed deep foundations. The use of the CMCs also allowed for the use of spread footings and slab on grade construction. The benefits of this value-engineering approach include economy in the foundation system, risk mitigation by not disturbing contaminated soils requiring expensive removal, and ease of access for future sub-slab upgrades with new tenants. Additionally, the use of recycled concrete aggregate as an LTP is more environmentally friendly than placing structural slabs with heavy steel reinforcement.Designing for the settlement of large warehouses is challenging because it requires changing how we typically perform our designs. For most structures, the slab loads are relatively light when compared to the footing loads, whereas for warehouses, the slab is heavily loaded compared to the relatively light footing loads. Thus, it becomes essential to perform three-dimensional analyses to confirm that the proposed CMC layout will provide uniform support of the slab and footing across a variety of loading scenarios (loaded bays vs unloaded or travel bays). The complexity of the designs for these warehouses generated interest in conducting large area load tests over a grid of multiple columns. The performance of the area load tests provided invaluable information on the effectiveness of the LTP and CMC spacing. In this paper, we present a general description of CMC ground improvement, the differences between ground improvement and traditional pile foundations, our typical design methodology for CMC design, and the modifications to that methodology for warehouses."

Jan 1, 2017

By Sastry Putcha, Santosh Mummaneni, Avasarala Swamy

"Inspection of bored pile hole bottom prior to placement of concrete is one of the most crucial element of foundation design and construction, especially for end bearing piles. Pile hole bottoms that are not cleaned well for sediments could potentially result in settlement. Although many projects have specifications in-place for drilled pile hole inspection, they are rarely implemented as the current available tools are either unsafe or cumbersome and costly, thus making it very unattractive for owners and contractors. Further, sometimes the post-construction nondestructive quality control testing such as PIT or sonic logging on piles resulted in unanswered questions related to soft bottom. This generates costly disputes with additional testing including concrete coring and possible repairs. Currently, there are several bored pile bottom inspection devices in USA, namely, SID, DID, and SQUID which can either provide video and photo documentation or measure sediments.“ShaftCam”, a patented advanced Digital Borescope, was invented to address the issues related to pile hole bottom inspection with its ability to measure sediments as well as photo and video documentation. Shaftcam device consists of 8-inch diameter bell with a camera, led lights, air hose connection and penetrometer with digital measurement that are connected to a control power box and laptop through a cable. The bell is fitted with a round clear open fiberglass skirt to form an open chamber. A simple motorized winch frame allows the user to lower the ShaftCam equipment gently to the bottom of the shaft at the desired location. Once the bell with camera is lowered to the bottom of the hole, air is pumped into the clear chamber to displace the water/slurry/polymer and get a clear view of the hole bottom to record the conditions and measure the sediment thickness and resistance. The skirt can also be enclosed and lowered to the desired location to allow for inspection of shaft walls.ShaftCam weighs less than 15 lbs. (6.8 kgs) in water and allows for inspection of the hole by one person in less than 30 minutes. Use of ShaftCam has saved significant time and money and thus allowed owners and contractors to readily accept and implement the quality control measures in many projects in USA over past few years."

Jan 1, 1900

By Maurizio Siepi, Bruno Vingiani, Claudio Asioli

"The article describes an emergency rehabilitation intervention executed at Buyo Dam, in Ivory Coast, to intercept a significant water seepage occurring through the foundation of this zoned earthfill retaining structure constructed in the late Seventies. To solve the problem, a 800 mm thick, 400 m long impervious cut-off wall (COW) was constructed on the right side of the embankment, operating from the dam crest and with the reservoir almost at its maximum level. The use of an innovative pre-mixed self-hardening grout, with a target hydraulic conductivity coefficient (k) lower than 10-9 m/s, was considered the only way to match the tight working schedule and the strict requirements for the filling material of the COW.Presentation of the Hydroelectric Scheme of BuyoThe hydroelectric scheme of Buyo, located at 6°14’28” N 7°20’45 W on the Sassandra River, in Ivory Coast (Figure 1), was built in the late Seventies for agriculture and power generation. With a reservoir of 8.3 billion m3 and an installed power capacity of 165 MW, enough to supply electricity to 111,000 homes, it represents an installation of great significance for this West African country."

Jan 1, 2016

By Gisele R. Passalacqua, Taylor Malangone, Subhash Mahali

New York City is a busy metropolis with 8 million people. New York has the largest public transportation system with 6 million riders a day throughout the subway system. Keeping this infrastructure in service is vital to the overall economy of the region. Hurricane Sandy proved to have a devastating impact on infrastructure in Metropolitan New York. New York City Transit is on the forefront to provide resiliency and maintain its facilities with the use of flood protection systems. This paper presents flood protection structures utilized at Hammels Wye substation site in Far Rockaway, Queens, New York. The site is in close proximity and surrounded by water. The subsurface conditions consist of loose silts overlain by medium dense glacial sand. The high groundwater level combined with limited access to the site presented challenges. A flood protection system consisting of flood walls was recommended for this site. In certain areas the flood walls consisted of retaining walls supported on micropiles. For other areas, the flood walls consisted of steel sheet piles with jet grout columns to reduce seepage below the walls. The effect of driving sheet piles with vibratory hammers on nearby existing structures is always a concern. Recently, hydraulic hammers with variable moment/frequency are being considered as a mean to reduce vibration effects during driving. In this project, an instrumentation testing program was performed to measure peak particle velocity during sheet pile driving utilizing the variable moment vibratory hammer. Plots of peak particle velocity versus frequency were generated. This paper will present the design aspects of the flood walls and construction challenges during installation. This will prove beneficial to engineers in both design and construction fields.

Sep 8, 2021

By Ryan T. Smith, Anthony Sahj, Alexander T. Darnell

Every second can count when trying to board a departing flight or catch a ride-share to your final destination. Hartsfield-Jackson Atlanta International Airport is in the midst of a project that aims to cut about 13 seconds between automated people mover trains (Plane Train) that move passengers between the terminals and concourses. The project involves extending the Plane Train tunnel west from its existing terminus under the domestic terminal. Working from inside non-public areas of the terminal, Keller North America, Inc. (Keller) incorporated systems of micropile-supported steel beams and grillage to both underpin existing columns prior to tunneling and support open-cut excavation at the tie-in of the new to the existing tunnel. Dewatering aided in mining a challenging section at the start of the drive of the mixedface, sequentially excavated tunnel and an automated instrumentation system monitored the performance of the construction and its impact to the terminal. Cut and cover egress and ventilation tunnels required braced support of excavation.

Oct 1, 2022

By Brenton Cook, Daniel Mageau, Larry Applegate, Aaron McCain

"Ground freezing was successfully used to create an impermeable barrier wall along 3,000 feet of the downtown Seattle waterfront as part of the Seattle Seawall Replacement Project. This $360 million re-development involved removing the original 1930-era seawall and replacing it with a new, seismically resistant concrete wall supported on fill soil improved by jet-grout. The replacement wall was one of the largest construction projects in the state of Washington at the time. Ground freezing is typically used as both a structural shoring wall and groundwater cutoff. However, at this project it was used primarily as a cutoff wall to stop groundwater seepage into the 16-foot deep excavation from the landside areas.The project was divided into ten boxes (sections), each typically 200 to 600 feet in length. Only a few boxes were under construction at one time to reduce the impact on tourist-dependent local businesses. Soil conditions in the freeze zone consisted of sand, gravel and silt fill with abundant wood and debris. Tidally influenced groundwater, much of it contaminated, was difficult and expensive to control using wells during initial stages of construction. For all subsequent stages, a frozen soil wall extending to about 35 feet in depth was used to stop groundwater seepage into the excavation. An additional benefit of ground freezing included elimination of potential settlement beneath nearby buildings, utilities, and the Alaskan Way Viaduct that would likely have occurred with the use of conventional dewatering wells. The frozen soil wall crossed more than 130 buried utility locations (including water, sewer, storm, electrical, fiber optic, phone, gas, steam) with no damage. The frozen soil wall was very successful and limited groundwater influx from the landside to the seawall excavation to a negligible amount so that pumping, storage and treatment of contaminated groundwater was essentially eliminated."

Jan 1, 2016

By Stephan A. Jefferis, Adrian H. Bath

"This paper draws together some themes on the durability of barrier systems, and particularly cementitious systems. For contaminated land and water retaining structures, durability can be poorly addressed at all stages of a project, from specification, to barrier material selection, barrier design including toe-in and through to performance assessment in operation. Permeability (hydraulic conductivity) is a dynamic property which will vary over time as reaction processes propagate through a barrier. However, laboratory testing, when undertaken, tends to be focused on short term tests with aggressive chemicals so that the effects of longer-term processes such as carbonation and leaching by permeating water are missed. For water retaining structures, carbonation and leaching actually may be the most significant processes affecting barrier performance as the groundwater adjacent to many water bodies can be otherwise rather benign (as regards bentonite and cementitious systems). These and other reaction processes have been modelled in the arena of nuclear waste repositories and procedures are well recognised. However, such procedures have yet to be widely adopted for the assessment of other barrier systems.INTRODUCTIONOver the last few decades there has been an enormous amount of laboratory research on the durability of barrier materials or more specifically papers reporting the results of permeability tests. Unfortunately there is a much smaller literature on scaling test results to barrier dimensions in the field or to required design lives. Although in the geotechnical industry durability research has been largely laboratory based, in the nuclear industry where relevant timescales are multi-millennia rather than decades, research has been heavily underpinned by geochemical modelling. A significant purpose of this paper is to examine the tools that may be used to analyse the results of tests on barrier materials used in geotechnical engineering, for example, for water retaining structures and contaminated land and draw the attention of the construction industry to the potential of the modelling procedures developed for nuclear repository assessments. Modelling can help to identify underlying processes and so augment information from laboratory testing focused on changes of physical properties such as permeability and strength."

Jan 1, 2016

By Robert Alperstein, Nidal AbiSaab, Joe Pastore

"This paper describes the design and construction aspects of the foundation support for a 57-story building currently under construction in lower Manhattan. The site is located near the East River with subsurface conditions consisting of about 40-ft [12.2-m] of unsuitable historic fill and soft plastic clay underlain by about 130-ft [39.6-m] of dense sand resting on bedrock. A mat foundation supported on unsuitable soils improved by jet grouting was selected for the project. Design concepts and selection of the engineering properties of the improved and natural foundation soils are discussed. The results of quality control testing and methods to verify design parameters during construction are presented.INTRODUCTIONNew York City (especially Manhattan) is known for its skyline of high rise structures. The geologic conditions in the New York Metropolitan Area influence the selection of foundations and feasibility of high rise construction as noted by Horvath (2013). These conditions include varying depth and quality of bedrock, multiple glacial events during the Pleistocene Epoch, and the effects of human modifications to the subsurface environment. Clusters of relatively taller buildings are generally located in Lower and Midtown Manhattan where sound crystalline bedrock is at relatively shallow depth beneath the ground surface and shallow foundations rest on the bedrock surface. In recent years the use of more costly high capacity driven piles or drilled caissons and deep basements has enabled the high skyline to spread to other areas."

Jan 1, 2016

By Harald Vogel, Johannes Lachenski, Friedemann Koetzel, Sebastian Schnell

In this paper, a digital subsoil approach, a work-in-progress, will be presented describing the transformation from a classical 2D to digital 3D thinking process in the design of geotechnical structures. Certain pitfalls as well as lessons learned are described, and the reader can understand that the digitalization process of the design of geotechnical structures is always a problem-focused approach by creating systems for certain processes rather than setting rules or regulations. Three project examples are presented. Two of the presented project examples feature a heterogeneous geology distribution and made it necessary for the design of the foundations to work with 3D subsoil and 3D calculation models. However, the digital 3D design process in the third project, an inner-city excavation pit, is driven by the complicated boundary conditions making it necessary to work in a parametric 3D design space. All projects have in common, that new processes had to be developed. The paper concludes with a flow chart describing the process of the elaborated digital subsoil approach.

May 1, 2022

By Brandon M. Robinson, Osman F. Besler, Dominik Gaechter

With the increase in population over the last decade, and anticipated population growth over the coming years, Norway is making significant investments in the Country’s infrastructure. Part of this investment in development starts with the Intercity development project in South-East Norway, which is the largest transport project in Norway. The Intercity Development project consists of 270 km (167 mi.) of new doubletrack rail, capable of train speeds reaching 250 km/h (155 mph). The new stations are centrally located in the major cities, in South-East Norway, to provide the benefit to as many citizens as possible. The goal of the project is to reduce the increase in traffic, which is coupled with an increase in population, and reduce the travel times between the cities. The Intercity Development Project has an anticipated completion date of 2034. The Sandbukta-Moss-Såstad (SMS) project, part of the Intercity development, includes 10 km (6.2 mi) of new double-track railway and is situated on the Østfold Line, near the city of Moss, Norway shown in Fig. 1. The 10 km SMS-section covers three open stretches and two tunnels, including 630 m (2,066 ft) substructure for double-track railways on the open line at Sandbukta. The Moss tunnel is a 1720 m (5,643 ft) long tunnel from Sandbukta to Moss center, including a 420 m (1,378 ft) long concrete culvert. The new Moss station includes an 800 m (2,625 ft) long station area. The Carlberg tunnel is a 2350 m (7,710 ft) long tunnel from Kleberget to Carlberg, including a 200 m (656 ft) long concrete culvert.

Sep 8, 2021

By Eleonora Di Mario, Colin B. Turnbull, Matthew G. Mills, Chengbin Miao, Wilhelm S. Degen

"In the past decade, the ‘zero-dredge’ philosophy has become the preferred option for the formation of marine seawalls and reclamations, compared to the partially or fully dredged options, as this solution presents several environmental advantages. Recent relevant project experience is presented herein in order to highlight key design principles and construction issues central to the successful construction and performance of a sloping rubble seawall founded on soft soil improved by stone columns. If designed and installed with proper quality control, correct treatment intensity and sensible construction staging, stone columns are a safe and cost effective method for seawall foundations. This paper provides guidelines with regards to the design, construction and quality control for the correct implementation of stone columns as a foundation element for sloping rubble marine seawalls.INTRODUCTIONBenefits of sloping marine seawalls founded on stone columnsTo suit the current environmental requirements in Hong Kong, recent projects are tending to favour zero-dredge solutions, such as the Hong Kong Boundary Crossing Facility and the forthcoming Three-Runway System. The installation of stone columns allows the underlying deposits, generally consisting of very soft to soft clay and silt (soft soil), to improve in strength to the extent that the seawall can be directly placed on the seabed. This negates the need to dredge the soft soil and, therefore, this ground improvement technique represents an ideal solution for zero-dredge projects.Stone columns can also provide several other beneficial effects, including: accelerated drainage, reduced settlement, increased slope stability and soil reinforcement in the event of an earthquake. Stone columns, in contrast to competing cementitious methods, are a very ductile foundation method. This ductile behaviour is part of the design concept of stone columns in soft soil. Past projects located in Hong Kong and elsewhere, with an improved soft soil layer thickness of over 15m, have shown that stone columns can remain fully functional in terms of both drainage and horizontal reinforcement, even after settlements of over 3m and lateral displacements of up to 1m have occurred."

Jan 1, 2017

By Piotr Kozlowski, Stanley L. Worst, Matthew J. Niermann

Circular secant pile shafts were installed along the tunnel alignments for both the Ohio Canal Interceptor Tunnel project in Akron, Ohio and the Ohio River Tunnel project in Louisville, Kentucky. The diameters ranged from 34 to 51 feet and the depths ranged from 49 to 107 feet. Verticality and concrete volumes were measured on all piles to verify compliance with the design, which for some shafts consisted of a finite element model with multiple openings using unreinforced concrete secant piles. All secant piles were drilled into rock to seal off the groundwater. This paper will discuss the design, construction and quality control of the secant piles for these projects. INTRODUCTION Many Midwest and Northeast cities have Combined Sewer Overflow (CSO) systems which discharge pollutants into waterways during wet weather events. One way to remedy this issue is to provide a temporary overflow tunnel. A temporary overflow tunnel connects to the combined sewer system and collects the overflow during wet weather events, storing the wastewater until the event has subsided. After the storm event, the stored wastewater can be pumped to the treatment facilities and processed as normal. Project Background – Akron, OH The Ohio Canal Interceptor Tunnel (OCIT) project was performed as a result of the Environmental Protection Agency’s (EPA) Consent Decree with the City of Akron, Ohio. This Consent Decree required modification of the existing Combined Sewer Overflow system. The resulting project consisted of a 27- foot diameter tunnel with multiple points of entry to capture the sewer overflow and prevent it from entering waterways. The tunnel is over 6,000 feet long and is as deep as 150 feet below the ground surface; see Figure 1 below.

Jan 1, 2019

By Patrick J. Hannigan, Frank Rausche, Rozbeh B. Moghaddam

Large diameter open-end pipe piles are increasingly used as deep foundations to support heavy onshore and offshore structures. During the driving process, several factors such as subsurface conditions, hammer type, hammer efficiency, pile type, plug conditions, temporarily increased base resistance, and loss of shaft resistance have direct impact on the driveability of large diameter open-end pipe piles. In a uniform subsurface condition, the unit shaft resistance increases with depth. Consequently, more resistance is accumulated as piles penetrate to greater depths which results in higher driving resistance. However, according to the friction fatigue analysis, the greater the number of shearing cycles occurring on a soil segment along the pile shaft, the greater the reduction of its shear resistance. As a consequence, since upper soil layers are subjected to a greater number of blows than those at greater depths, they have a relatively lower resistance compared to what would be calculated with standard geotechnical analysis methods. As a result of this progressive and nonuniform loss of shaft resistance with driving, blowcounts tend to increase at a lower rate than expected from traditional analyses. This paper discusses one of the approaches to the driveability analysis with the geotechnical friction fatigue consideration. It also shows comparisons between predicted driveability obtained from wave equation analysis and field driving records. All analyses were performed for a 2.134 m (7.0 ft) diameter open-end pipe pile installed at a total depth of 192.90 m (554 ft). Two separate static resistance and wave equation analyses were completed for the case study presented in this paper: 1) Friction Fatigue analysis based on the recommendations of Alm and Hamre (2001), subsequently referred to as the FF model, and 2) Standard Driveability analysis based on soil set- up factors, hereafter referred to as the SD model in this paper. Results from analyses included the shaft resistance distributions compared to the result of the signal matching analyses determined from the pile dynamic measurement. Furthermore, predicted blowcounts were compared to observed blowcounts during the pile driving. The comparison analyses indicated a 54.4 percent resistance loss of the Static Resistance during Driving (SRD) due to the geotechnical friction fatigue corresponding to a 46 percent reduction in total resistance. The analyses also showed that average predicted blowcounts using the friction fatigue were 6.4 percent lower than measured blowcounts, whereas, the standard driveability approach showed 42.1 percent higher blowcounts compared to the blowcounts shown in the driving log values.

Jan 1, 2019

By Karen C. Armfield, Gisele R. Passalacqua, Joanna Smith

New York City is an urban environment with a history spanning over 200 years. The coastline of New York has changed over the years. In the East River, old bulkhead and remnant of relieving platforms together with variable bedrock elevations pose challenges in the design and construction of deep foundations. This paper presents a Case History of high capacity deep foundations along the Franklin D. Roosevelt (FDR) Drive on the Upper East Side in New York City. The project consists of a ramp that overpasses the FDR Drive allowing heavy trucks to access the Marine Transfer Station (MTS) facility built over the East River. Large diameter drilled shafts and mini-piles socketed to bedrock were designed and constructed. Remnant of old bulkhead was encountered at the site and a Ground Penetrating Radar (GPR) investigation was completed during the subsurface investigation phase of the design. This paper discusses details of the subsurface investigation program and design methodology of the high capacity drilled shafts and mini-piles. It also describes construction methods and results of Osterberg Load tests documenting the field values of skin friction through the rock socket. Other construction challenges include construction and drilling rock sockets for drilled shafts over sloping bedrock. 1. INTRODUCTION New York City is a renowned urban city that always calls for the most delicate, yet complex, and robust superstructures and most importantly substructure designs. The historic preservation of this large 200 years old city of 319 square miles is ever changing. Shorelines are often extended to accommodate new infrastructure and very often many miscellaneous structures are discovered below the ground surface. The East 91st Street Ramp was constructed to provide access to the East 91st Street Marine Transfer Station over FDR Drive and York Avenue. Another alternative ramp will be relocated to the South Bound (SD) of the FDR Drive at 92nd Street. A subsurface exploration program was completed in accordance with the New York City Department of Design and Construction (NYCDDC) general requirements, Section 4.5, to perform subsurface investigation along the FDR Drive in Manhattan, New York.

Jan 1, 2019

By H. Cheng

The Bohai Oil Company has applied all together 11 jack-up oil drilling rigs (movable platforms) (1) which can be classified in terms of their forms of foundations into two types: the integ­ral mat and the column legged, as demonstrated in figure 1. Figure 1 a) indicates the entire structure of the sunk cushion type, i.e. the one with a box-like sunk cushion serving as its foundation by directly sitting on the sea bed. The length, width and height of the outer sides for the sunk cushion stand at 45.8 x 38.0 x 3.3m ( for Rig Bohai No.2 ) and 50.6 x 33.2 x 4.88m ( for Rig Bohai No.6 ), the relative areas of theirs being 1475m2 and 2008m2 respectively and both bigger than the plane areas of the rigs. With a view to realize a convenient drainage of mud while sinking, two holes of 14 x 14m and 32 x 18m in size are constructed in the center part of the sunk cushion. When work sets off, the underside of the sunk cushion operates as a foundation, the sunk cushion being connected to the platform by hull columns which transmit the load of the platform down­wards to the sunk cushion that passes it further onto the subgrade. [ ] Column legs for rigs may also be grouped into two categories considering their features: columns with and without boots. The bodies of boot columns are made up of trusses, whose bottoms, are boot-shaped with a big diameter. The diameter of boot columns of the rigs applied by the Bohai Oil Company shows bigger and it may reach 12 or 18m. In the boot columns, the transmission of the platform's weight into soil is done by the underside areas of boots. While in the case of the vertical columns, which are of cylinder columns of steel with sealed bottom ends shaped inverted arch, the entire drilling platform is supported by the carrying force delivered by the bottoms of these steel cylinders and the frictional force rendered by their outside walls. Such a type of columns is featured by a small diameter, 3m in general. Figure 2 exhibits the schematic diagram of sections regarding the two types of column legs.

Jan 1, 2010

By Balasubramani M., Ramana P. V., Bairagi K.

This paper is a case study of an earthen Cofferdam, constructed for a deep excavation at Intake location in river Aaundha, Maharashtra, India. A 12 m (39 ft) deep excavation was made to construct the Intake well. The natural soil profile at this location is clay followed by rock. An earthen Cofferdam of maximum height 7 m (23 ft) was made around the periphery of the excavation. Cofferdam embankment and excavation slopes were analyzed using the finite element software PLAXIS-2D. Clayey sand was proposed as filling material during design, but clayey soil was used for the embankment formation during execution. The embankment was built up to 5m height in July 2017 and completely submerged due to monsoon. In February 2018 embankment height raised to 7m (23 ft) by filling the soil over the existing submerged embankment. After a few days of completion of the Cofferdam construction, the inside slope of the embankment had started sliding due to continuous dewatering. The design and execution of deep excavation with earthen Cofferdam for waterfront structures are challenging. The selection of filling material for embankment formation and dewatering techniques plays a vital role in the safety and stability of the embankments. Although all the safety measures were taken during the design, execution challenges are unpredictable.

Nov 1, 2022

By Robert Bachus, Nikolaos Machairasm, Allen Cadden

Data Interchange for Geotechnical and Geoenvironmental Specialists (DIGGS) is a data transfer standard that is gaining widespread acceptance in the geotechnical and geoenvironmental communities. Originally developed using funding from the Federal Highway Administration (FHWA) to efficiently capture data related to geotechnical boring logs, cone penetration test (CPT) soundings, and lab testing results, the data transfer protocol is rapidly gaining traction. It has been shown to have beneficial impacts in other allied areas where disparate parties (i.e., consultants, contractors, vendors, etc.) routinely publish/submit data as part of project deliverables. The historic problem is that many of these submissions use paper copies (i.e., .pdf images) to transmit valuable data for the project… data that may extend beyond the “technical” aspects of the project (e.g., equipment operating conditions, construction production rates, project costs, etc.). These data could be used by multiple parties to assess project performance and safety, as well as to track productivity, etc. Currently, in the limited situations when actual data are compiled and transmitted, the data often are submitted as an author-specific (and often proprietary) software application and must then be re-entered into other software applications (e.g., analysis software, database, etc.) for use beyond simple data collection. An initiative undertaken by the Geo-Institute (G-I) of the American Society of Civil Engineers (ASCE) focuses on exploiting the full potential of DIGGS to geoprofessionals both within and outside of the transportation community. The deep foundations industry represents one community that could benefit significantly from using DIGGS. Data of interest to DFI members include production records, quality assurance information (e.g., verticality and alignment, concrete strength), and, importantly, load test results. When adopting DIGGS, users need not modify how they capture data, but rather will use DIGGS as a vehicle to transfer data to other applications in a standard format where it can be shared, used, stored, and retrieved. This paper and associated presentation will describe DIGGS and demonstrate how DIGGS can be used effectively within the deep foundations community.

Jan 1, 2019

By Paul C. Schmall, Kevin Clarke, Paul J. Lewis, John M. Stanbury

"The $200M rehabilitation of the more than 100-year-old Gowanus Flushing Tunnel and pumping station located on the Gowanus Canal in Brooklyn, NY required deep excavations in an extremely congested urban environment. The environment posed significant challenges, including: support of excavation for protection of existing structures, excavation through man-made fill while eliminating groundwater inflow due to potentially contaminated groundwater chemistry; discharge and disposal impacts; and potential settlement of surrounding structures. This paper will present the design and construction challenges associated with the construction of a new combined sewer overflow (CSO) chamberwhich included a jet grout bottom seal, to mitigate groundwater inflow during excavation. The foundation for the finished structure also included a unique system incorporating the jet grout bottom seal elements with deep jet grout columns (piles) acting as the foundation system for the final structure. Design and construction challenges included highly variable soil conditions such as man-made fill, obstructions from previous construction, presence of an organic stratum, and conflicts with existing timber foundation piles. The jet grout bottom seal was constructed in loose sands with the deeper jet grout foundation elements extending to bear on a dense sand stratum. Challenges associated with the bottom seal included grid spacing and construction sequencing. Wet in wet sequencing was used to mitigate potential windows in the bottom seal further complicated by shadowing from existing timber foundation piles.Introduction And BackgroundModernization of the Gowanus Tunnel Pumping System required deep excavations in the extremely congested urban environment of Brooklyn, NY. The project location is shown on Fig. 1 and 2. The focus of this paper is to present the design and construction challenges associated with the support of excavation, control of groundwater, and ultimate foundation support for the combined sewer overflow (CSO) bypass chamber extension. The project site was tightly constrained by adjacent, active roadways and underground utilities, as well as residential and industrial structures. Therefore, excavation support was required to limit ground movement and maintain the integrity of the surrounding facilities. Excavation depths to as much as 16 ft below ground level, 8 ft below groundwater, required that seepage and groundwater be controlled so as to minimize pumping and disposal of groundwater and maintain the surrounding groundwater levels to avoid potential settlement of adjacent roadways, utilities, and structures. In addition, the subsurface conditions required that the proposed CSO bypass chamber extension be supported on a deep foundation to avoid differential and total settlements that may be detrimental to the existing and expanded structure. A plan view of the existing CSO bypass chamber and the proposed extension is shown on Fig. 3."

Jan 1, 2016