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By P. Arz

With a total of five basement levels, ground floor and a further six levels above grade, construction of the Kö-Galerie building, on the Königsallee, in the centre of Düsseldorf, was completed with all the difficulties which accompany property development today in the inner city. To meet the intermediate and final deadlines, ad­vanced building techniques were used. Notable among them are the top/down method for simultaneous construction upwards and downwards from an intermediate level, and the use of pre-fabricated composite columns in drilled shafts for the main load-bearing foundations as well as diaphragm walls designed as permanent structural wall of the basement.

Jan 1, 1989

By Challa Venkata Rami Reddy, Anindya Roy, G. R. Konni

This paper presents the results of pile lateral capacities obtained from both conventional design and fullscale pile lateral load tests. Conventional design using P-Y curve analysis is very commonly being used by designers; designers use well accepted software programs like Lpile and Allpile for analysis. However, these programs do not cover the soil models to simulate engineering behavior of marine carbonate sands; which generally have different engineering behavior than silica/quarts sands. In this study, the existing soil models for common sands have been used to assess pile lateral capacities and these results are compared with the results from full-scale instrumented pile lateral load tests performed in compacted marine carbonate sand fills of artificial island constructed for oil and gas facilities in Abu Dhabi. The objective of this study was to verify the applicability of the existing sand soil models for carbonate sands and also to verify the associated conservatism in the pile lateral capacities. This study shows that the actual pile lateral response is much stiffer than what was anticipated through the LPile analysis. Therefore, further research focus may be required to capture the engineering behavior of the marine carbonate sands to develop specific P-Y curves.

Sep 8, 2021

By Michael W. Neill, O&apos

This presentation addresses some of the problems encountered in estimating the capacity of drilled shafts and augered, cast-in-place piles in soft rock. Methods to quantify side and base resistance are suggested. However, the methods that are described should always be verified locally by performing load tests.

Jan 1, 2001

By A. David Miller, Douglas M. Barber

"The Rocky Mountain Arsenal was used by the military to produce chemical warfare agents and incendiary munitions for use during World War II and later by private companies for the production of industrial and agricultural chemicals. After an investigation performed in accordance with CERCLA confirmed significant levels of contamination due to the common industrial and waste disposal practices of the era and the discovery of over 300 species of wildlife inhabiting the land the Rocky Mountain Arsenal became a wildlife refuge and contamination cleanup efforts began. Three lime basins originally used to treat wastewater from the chemical production were decided to be contained in place, requiring a seepage barrier installed around the perimeter of the site to further prevent groundwater/contaminant migration. This case study will discuss the successful installation of a soil-bentonite cutoff wall around the area using deep soil mixing. Highlights of this case study will also include a discussion of the challenges faced due to construction activities performed with Level B Hazmat PPE requirements as well as added challenges brought on by the Winter season, after the project was delayed due to a positive air monitor detection for the chemical weapon Lewisite during construction of the work pad.INTRODUCTIONThe Rocky Mountain Arsenal (RMA), located just outside of Denver, Colorado, was established by the United States Army in 1942 to produce chemical warfare agents and incendiary munitions for use during World War II. Following the war, and as weapons production decreased, portions of the site were leased to private companies for the production of industrial and agricultural chemicals. The principal lessee, Shell Oil Company, manufactured mostly pesticides at RMA facilities from the early 1950s to the early 1980s.In 1984 an investigation began in accordance with the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) and confirmed significant levels of contamination due, in large part, to the common industrial and waste disposal practices of the era. It was also discovered that over 300 species of wildlife inhabited the land in the absence of regular human activity, including a group of bald eagles, leading to the passing of the Rocky Mountain Arsenal National Wildlife Refuge Act in 1992."

Jan 1, 2015

By Jeffrey M. Taylor, Arturo Ressi di Cervia

"Construction of the drilled shafts for the Brightman Street Bridge Replacement Project were not only challenging due to working over the water but were also challenged by changed soil conditions, concurrent work being performed by an adjacent contractor on the same project, environmental restrictions and severe winter conditions. A total of 36 x 8 foot (2.44m) diameter drilled shafts with 7.5 foot (2.31m) rock sockets were installed for the East and West bascule piers. This project also included Osterberg Cell load testing on two production drilled shafts at both the East and West bascule piers. The results from the load test program were used to fine tune the design of the drilled shaft rock sockets. From a constructability standpoint the reverse circulation drilling method with a pile top drill rig proved to be an excellent choice for drilling the overburden and rock sockets of the large diameter deep drilled shafts. INTRODUCTIONThe replacement Brightman Street Bridge spans the Taunton River between Fall River and Somerset in Massachusetts.The new crossing is located approximately 1500 feet (450m) upstream from the existing Brightman Street Bridge, which was built in 1908. The new mainline bridge includes nine spans totaling 1725 feet (525m). A bascule type moveable span will be located in the middle of the Taunton River and provide a 200 foot (61m) open channel centered about the 400 foot (122m) navigational channel. The bascule span, which has a span length of 409 feet (124.7m), will be a trunnion-type four leaf structure with a solid deck. A site plan is shown in Figure 1 Contract 3, which includes construction of the foundations for the East and West bascule piers, was bid on December 19, 2000 and was awarded to Modern Continental Construction Company (MCC) on January 24, 2001. MCC in turn awarded the subcontract for the installation of the drilled shafts to TREVIICOS Corporation, which started mobilizing in June of 2001.The scope of work for the drilled shafts of Contract 3 consisted in installing 18 drilled shafts in three rows on each side of the river to support the bascule piers located in the middle of the Taunton River.The foundation plan for the bascule span is shown in Figure 2."

Jan 1, 2004

By Thomas G. Tavernaro, Jeffrey A. Schaefer

"The $106 million Olmsted Approach Walls Project, completed in the spring of 2004 by Massman Construction Co., Kansas City, MO, is one phase of a new $1.4 billion Corps of Engineers locks and dam facility located at Mile 964 on the Ohio River, approximately 17 miles (27.4 km) upstream of its mouth at the Mississippi River. When completed, the Olmsted Locks and Dam (Figure 1) facility will replace two aging locks and dams (Locks and Dams 52 & 53) built in the 1920’s, and produce an estimated $600 million annual economic benefit to the nation through reduced lockage time and operation and maintenance costs. PROJECT OVERVIEWThe Olmsted Approach Walls Project consisted of “in-the- wet” construction of four fixed nose pier structures, four floating concrete approach walls, one fixed wall and related underwater excavation, grading and stone placement. Over 12,000 tons (11,000 tonnes) of structural steel and pre-cast concrete elements, up to 335 tons (304 tonnes) in weight, were safely erected during the project.To support these massive structures, the Louisville District of the U.S. Army Corps of Engineers teamed with INCA Engineers, Inc., Bellevue, WA to design thirty seven 10’ (3m) diameter shafts (cast-in-place steel-shell piles) capable of maintaining elastic behavior below ground while resisting barge impact loads, extreme head-on collisions from runaway tows, and environmental forces from river current, wind, and seismic events.The shafts (typically 150’ (45.7m) in length) were founded 100’ (30m) into the riverbed through alluvium, a very consolidated fine sand and clay Cretaceous soil, and finally into a hydrothermally altered rock. Thirty seven shafts were installed under open river conditions at the site, a group of four shafts at each nose pier-pylon location (Figure 2), and 21 at the fixed land wall. Due to difficulty in achieving the required casing tip elevation the team developed a design modification that was successfully implemented for 27 of the shafts.Concurrent with the work at Olmsted, eleven pontoon segments for the four floating approach walls were constructed at a graving yard in Paducah, KY, developed by Massman Construction Company specifically for the project. While the pontoon geometry varied, the pontoons averaged 350’ (107m) in length, 40’ (12.2m) in width and weighed 4,500 tons (4,082 tonnes). The longest of the four walls, at 1,700’ (518m) was comprised of five interconnected pontoons."

Jan 1, 2006

By Peter Cali, Wesley Schmutzler

"The Deep Mixing Method (DMM) was employed to raise and support the LPV (Lake Pontchartrain and Vicinity) -111 Levee in New Orleans. Even using innovative technologies, the tight schedule to achieve the 100 year elevation by June 1, 2011 was a daunting endeavor. The size and scope of DMM proposed for LPV-111 was on a scale never attempted outside of Japan. Over 1.65 million cubic yards of DMM was installed. LPV-111 is adjacent to the Bayou Sauvage Wildlife Refuge, which is the largest urban National Wildlife refuge in the United States. By utilizing DMM to control settlement and improve stability of the taller levee, side slopes were steepened from the conventional 1V:4H to 1V:2.85H, thus avoiding encroachment into the Bayou Sauvage and reducing the amount of clay needed for the completed levee. The COE utilized Early Contractor Involvement (ECI) for this contract. The ECI process allowed for input from the DMM contractor, TREVIICOS South, in order to optimize equipment resources and material requirements. This paper gives an overview of the extensive DMM requirements for LPV-111 and explains the benefits of the ECI process.IntroductionDuring hurricane Katrina the levee that constitutes LPV-111 was overtopped and breached in several locations. The United States Army Corps of Engineers (USACE) was presented with the task of increasing the level of the flood protection around New Orleans after Hurricane Katrina to the 100- Year hydraulic grade - the level of protection that provides risk reduction from a storm surge that has a 1% chance of being equaled or exceeded in any given year - and the firm project completion deadline was June 2011.LPV-111 is located in East New Orleans and a large portion of the levee is adjacent to the Bayou Sauvage National Wildlife Refuge. The levee could not encroach on this area. This provided a limited footprint for the levee and made construction of conventional levee difficult, if not impossible. The total length of the project was 5.3 miles. Included in the project was the rehabilitation of one main pumping station and one smaller pump station for water management within the refuge. Short sections of “T” wall were used at the tie in at the Lake Borgne Surge Barrier, the main pump station and the CSX Railroad crossing"

Jan 1, 2017

By Ryan Sullivan, Lisa Smiley, Jewels Stover

The Westerly Storage Tunnel (WST) Project is part of Project Clean lake, the North East Ohio Regional Sewer Dist years. When completed in 2020, WST will be nearly 2 miles of 25-ft diameter tunnel 200-250 ft below ground. The storage tunnel will manage higher flow volumes, keeping stormwater out of the combined sewer system reducing overflow occurrences. Three deep shafts provide access to the tunnel at the tunnel boring machine (TBM) launch and retrieval sites, as well as a vent shaft. Support of excavation for the access shafts was constructed utilizing unreinforced concrete diaphragm walls. This innovative, value-engineered alternate design significantly reduced risks associated with conventional secant piles combined with a rib and liner plate system. Implementation of the diaphragm wall technology resulted in a water tight, continuous shaft keyed into rock. This case study examines the design, methodology, and installation challenges unique to each shaft, as well as the benefits of the final product to the overall project.

By R. Radhakrishnan, C. Gunasekaran

"Calicut Bypass Phase-II project included construction of 7 m high embankment over soft compressible clays up to 18 m in thickness. Approx 1.5 km length of road out of a total 5 km length consisted of abandoned paddy fields which were low lying, waterlogged and marshy in nature. On the basis of excellent results achieved in earlier phases of the by-pass construction, ground improvement work by installing pre-fabricated vertical drains (PVD) was undertaken to stabilize the embankment foundation along the weak clay areas prior to road pavement construction to avoid large post construction settlement as well as to improve the lateral stability during and after embankment construction. This project perhaps stands out as one of the highway projects completed within a very short time period of total 18 months including four month long heavy monsoon period, when embankment construction was not possible and construction of two bridges across rivers. All activities including the ground improvement had to be programmed and completed within the shortest time period possible. The paper discusses details of the extensive ground improvement and soil instrumentation carried out for the project and will illustrate how careful planning and execution can reduce the period required for highway projects involving ground improvement.INTRODUCTIONPhase-II construction of Calicut by-pass was undertaken on a priority basis by the State of Kerala in 2014. The main contract was awarded to M/S ULCCS Ltd, Kozhikode, Kerala and the ground improvement work was awarded to M/S Geo-Enviro Engineers P Ltd, as specialist agency to design and execute the work.Soil investigation carried out confirmed thick soft clay deposits below GL in three areas along the road alignment totaling approx 1.5 km in length. These areas were low lying, waterlogged and marshy in nature. Highway embankment had to be constructed up to 7 m in height above existing GL to form the proposed road alignment along these areas. On the basis of excellent results achieved in earlier phases of the by-pass construction using pre-fabricated vertical drains or PVD (R. Radhakrishnan, 2006), ground improvement using PVD had been included in the contract to stabilize the embankment foundation along the weak clay areas prior to highway embankment construction to avoid large post construction settlement as well as to improve lateral stability during its construction."

Jan 1, 2015

By Richard D. Luark, Fernanda S. Madrona

Deep foundation construction in highly developed urban settings pose unique challenges of working with deep excavations in a relatively confined area while preserving the integrity of nearby structures. For construction of the below grade parking for two, 40-story residential high-rise towers, shoring walls were required to support the maximum 70-foot-deep vertical excavation in downtown Seattle, Washington. The design of the excavation support system consisted of soil nails combined with closely spaced vertical elements to allow the top row of soil nails to be installed up to 10 feet below the ground surface avoiding conflicts with adjacent underground utilities. To limit deflections next to a seven-story building, the upper rows of soil nails were post tensioned. An instrumentation program was implemented to monitor the deflections in the shoring walls by means of vertical inclinometers and optical survey monitoring. The shoring wall performance, designed to limit deflection to less than 1-inch to meet the City of Seattle requirements, was validated by the instrumentation program. This paper provides a discussion of the design and construction of the shoring walls as well as the monitoring data collected from the instrumentation system. PROJECT INFORMATION The project consisted of two residential high-rise towers, with five levels of below grade parking, located at 707 Terry Avenue Seattle, Washington. The project site covers a half city block, approximately 120 feet by 240 feet, and is bounded by Terry Avenue to the east, Columbia Street to the north, Cherry Street to the south, and an alley to the West. Prior to the development, site was occupied by surface parking. A 7-story concrete building with two stories of below grade parking, owned by the Archdiocese of Seattle is located just west of the 16-foot-wide alley. Numerous below grade utilities consisting of electrical, telecommunications, gas, water, sanitary sewer, steam, and storm drains, surround the project. The perimeter below grade parking walls extended within inches of the property boundaries. Topographic relief across the site was on the order of 8 feet. Figure 1 illustrates the site plan view.

Jan 1, 2019

By Andrew McNamara, Stuart Norman, Matthew Dearing, Michael Pelken, Asha Panchal

The deep foundations industry has largely remained unchanged since in the advent of CFA piling in the 1960s. Piles have consequently been designed and constructed following the traditional codes and standards without much regard for optimising in-life efficiency or end-of-life reuse. After existing developments have been demolished there is little motivation to reuse existing piled foundations as their load bearing capacity and structural integrity cannot be verified. Therefore piling contractors are increasingly spending more resources on coring through existing piles, only to be replaced with larger diameter or deeper piles. The hollow element of the HIPER® Pile provides access to the entire length of the pile to permit inspections and a shaft in which the pile can be extended if needed. This paper presents and compares the embodied carbon savings, both during construction and through foundation reuse, from a HIPER® Pile scheme compared with the traditional solid pile scheme. A discussion on the benefits of this technology and its implications on warranties and approvals is also presented to motivate the foundations industry to embrace whole lifecycle assessments and support the journey to net-zero carbon.

May 1, 2022

By Venkata Krishnaiah Yeddala, Sai Vivek Adari, Suresh Kumar Velugu

Assam cancer care foundation (ACCF) proposed the construction of hospitals and related facilities across 18 locations in the state of Assam-India. Tezpur is one among the 18 locations of Assam with high seismic risk. The strata at the site are comprised of mostly fine silty sands of lower SPT- N values. The water table is also encountered and ranging from 1 m to 2 m below EGL. Since the site lies in seismic zone V as per IS 1893, detailed liquefaction analysis is carried out for all five boreholes and indicates that soil is liquefiable and ground improvement is inevitable up to a depth of 15 m below existing ground level. To mitigate the liquefaction potential and enhance the seismic performance of the soil, ground improvement using stone columns by Wet top feed Vibro-replacement method is proposed. Also, the differential settlements can be avoided effectively under the raft foundation with Vibro Stone Columns. In this paper, field test validation results such as Pre and post-SPTs and ECPTs to access the extent of ground improvement, along with other information adopted in this project presented.

Nov 1, 2022

By Babu K. V., Samyukta P.

The energy demand in India is expected to show increasing growth in the next few decades. The oil companies in India are revamping the existing oil refineries as well as constructing new refineries across the country to meet the energy demands. Most of the refineries in India are located along the coastal region because of the ease of transporting crude materials. Considering the criticality of the structures as well as soil conditions in the coastal region, pile foundations are used in refinery plants. In India, non-displacement piles in the form of bored cast-in-situ piles are used to support structures. In a few circumstances, displacement piles in the form of driven cast-in-situ piles are also being used to support critical structures. This study presents the performance of non-displacement and displacement piles for similar ground conditions at the same project location. The pile load test results have shown that the settlement observed for displacement piles is lower than compared to non- displacement piles for a given loading and soil conditions. This shows that the performance of displacement piles is slightly better in comparison with that of non-displacement piles.

Sep 1, 2022

By Kaustuv Bhattacharya, Manish Kumar, Nirbhay Singh, Prodyot Kr. Ray, Praveen Soin

This paper highlights salient features of an excavation 38 m (Length) by 10 m (Width) by 24 m (Depth) carried out in Central Kolkata. Secant pile wall (SPW) formed using a combination of alternating 1200 mm & 800 mm diameter piles was used. Six layers of struts and waler beams, including bottom slab were utilized as lateral restraints to piles. The geotechnical profile for excavation zone was predominantly silty sand to sandy silt. The profile is characteristic of river channel deposit usually encountered in Kolkata. Temporary stage analysis (including seepage analysis) and design were carried out in FEM softwares. Design checks for clay bursting, piping, bottom heave, etc. were also carried out. Extensive instrumentation and monitoring were carried out during the excavation period to check parameters such as ground movement, pile movement, piezometric heads, etc. as per review levels. During excavation, ground improvement using Tube-a-manchette grouting technique was also required to be carried out as per field observations. The paper discusses some of the major challenges faced as well as measures taken to counter them, during deep excavation carried out in silty soils in a very congested Urban setting in the heart of a Megacity.

Sep 1, 2022

By Arunsiva R., Sivaranan S., Venugopal B., Kumaran M.

Being a rapidly developing country, India is undergoing a massive infrastructure phase change remarkably. The construction industry is already set to boom, but the time and space constraints necessitate the employment of heavy plants and machinery to take the foundations deeper than ever. Operating such machinery on soft or poor ground conditions without a good working platform leads to uncertainties with massive loss of men and machinery. Plenty of such cases can be observed on construction sites across the globe. Unfortunately, forming a temporary working platform is given least to no importance in the construction industry, particularly ground engineering. This glitch can only be addressed through standard guidelines or codal recommendations on designing and implementing temporary working platforms issued by regulatory bodies. The present paper highlights the importance of providing the working platform, existing design method for working platforms such as TWf 2019:02 of Temporary Works forum, Building Research Establishment BR470 and a brief discussion on the design and construction of the geosynthetic reinforced working platform with a case study is also included. A pitch has been made on the importance of Indian codes/guidelines for the design and construction of temporary working platforms. These guidelines will ensure the safety of the men and heavy machinery and, in addition, increase the productivity of foundation construction irrespective of weather conditions and also become part of the regular construction scope.

Sep 1, 2022

By Paul Hewitt, Aaron Rastall

The New South Wales South Coast rail corridor is key infrastructure for both freight and passenger transport. Geomorphological and geological evidence suggests that land instability has been widespread throughout sections of the rail corridor, long before the first documented record of landslide activity in 1879. Major landslides occurred along a 25-km length of the South Coast Railway connecting Sydney and Wollongong because of significant rainfall events of the late 1980s. Since this time, several sites have been identified as subject to instability and treated progressively under a risk priority and safety management system. Two such sites comprise a station footbridge and overhead wiring structure (OHWS), both founded on high embankments overlying colluvial materials resulting in the structures’ potential movement and associated stability concerns. This paper presents these two sites as case studies, and discusses the project geology, geotechnical models developed, interpretation of monitoring data, and successful remediation of the rail structures using sleeved bored piles. The sleeved pile system was used to isolate bored piles, which separated the bridge foundations and OHWS from the moving soil mass to ensure the piles can carry the rail structure loads, unaffected by downslope soil movements.

Nov 1, 2022

By Vijaya Bhushan Rao, Ali Semercioglu, Jason Redgers

Large diameter steel water tanks with high storage capacities impart heavy loads deep into the ground, generally requiring deep foundations to adequately support them. The use of ground improvement as a sustainable and cost effective alternative is tempting but the design of the foundations for such heavily loaded, thin-shelled structures have to meet several performance requirements such as bearing capacity, limiting the specified total settlements, typically limiting the radial differential settlement to 13mm over 10m along the circumference and dishing settlement from edge to center of 1/120 as per standard API 650 Appendix B as well as the mitigation of liquefaction induced settlement risk. Any inadequacy in the soil investigation, geotechnical design, or misrepresentation of stresses of the foundations may lead to serviceability compromise or potentially catastrophic failures. Therefore, the selection of the foundation is dependent on the availability of suitable ground report and the limitations imposed by operational requirements. Two such case studies are evaluated and compared in this paper, with tank diameters ranging from 41 to 106m in the Kingdom of Saudi Arabia, (KSA) which were founded on two types of soils and supported on deep foundations i.e., stone columns and bored cast-in-situ piles.

Oct 1, 2022

By Pete Howell, Patrick Granitzki, Alicia Plinio, Janitha Batagoda

The New York City Housing Authority (NYCHA) Red Hook Houses was subjected to damage during Superstorm Sandy. As a result, the NYCHA has an ongoing project known as Restoration Associated with Sandy Recovery Program to improve the resistance against future storms. The specific project included 28 residential buildings and several service buildings within the Red Hook Development. The subsurface conditions within the eastern portion of the site included existing fill material underlain by varying stratums of very loose, loose and medium dense silty sands followed by very soft to medium stiff clay or dense silty sands. The western portion of the site included existing fill material, very loose to medium dense silty sands and organic clayey silts underlain by very soft to medium stiff sandy silts. Based on the geotechnical report, a conventional driven steel pile system was specified containing two pile depths. As part of the project bidding, an alternative pile type was recommended and analyzed to provide quicker installation, reduce vibrations, reduce noise, and provide relatively large cost savings. Due to relatively high lateral loading, an innovative double steel casing drilled displacement piles was proposed as the alternative pile option. Field testing proved the piles capable of the required project capacities and the use of drilled displacement piles as the best alternative for the project and accepted by the NYCHA.

Oct 1, 2022

By Yazen Khasawneh, Yao Zhang

Upgrading and maintenance programs were proposed at a power generating plant in Indiana. To perform construction activities associated with the proposed upgrading and maintenance, a LR11350 crawler crane with a dead load of 1,500 ton was required in the vicinity of existing plant structures. The contact pressure from the crane tracks for the heaviest lift, maximum reach and angle (worst loading condition) were estimated by the rigging engineer to be on the order of 84 psi. Several concerns were raised regarding the total and differential settlements while the crane is in operation and the induced stresses on existing underground utilities due to crane loads. Three-dimensional finite element simulations were conducted using hardening soil model for the subsurface soils and elastic model for the other structural elements (underground utilities and crane mats) to optimize the configuration of the proposed crane foundation. It was found 1-foot thick engineered steel mats underlain by a 1.5-foot thick crushed stone pad will provide enough support to the crane. It will also control the settlement to the allowable limit and maintain the stresses in the underground utilities within tolerance. INTRODUCTION A LR11350 heavy lift crawler crane was proposed as part of an upgrade program at an existing power plant in the state of Indiana. The proposed crane will be sitting on an open ground in the vicinity of existing plant facilities, with multiple underground utilities going beneath the proposed footprint of the new crane pad. The existing utilities are of diverse kinds, including sanitary sewer corrugated metal pipes, electrical conduits and variable steel water/oil drain pipes. The safety and functionality of these underground utilities are critical to maintain the proper operation of the power plant. Therefore, the design of the new crane pad foundation system is of essential to control the ground settlement and the imposed stresses to the existing utilities (Davie et al., 1998, Scott 2017). To ensure all utility locations and depths are identified, the proposed footprint was thoroughly surveyed. Information in regard to each identified utility was provided by the owner. Subsurface explorations were conducted using geotechnical soil borings and soundings to evaluate the ground conditions and generate soil profiles. Numerical simulation and analysis utilizing finite element method were performed to design the crane pad foundation system and evaluate the responses of the utilities. This paper summarizes project information, geotechnical conditions and then focuses on the finite element analysis in assisting the design of crane pad and the utilities evaluation.

Jan 1, 2019

By Vijaya Bhushan Rao, Jason Redgers

A substantial lifestyle destination in the United Arab Emirates, in the Emirate of Abu Dhabi comprising of 1315 villas, town houses and non-residential leisure facilities is built over an area of 280 hectares of former mangrove areas, natural sands and reclaimed lands. Large-scale subsoil investigations including field and laboratory testing carried out dividing the entire site in to 7 clusters. This investigation revealed alternating layers of loose sands and silty clays within the load influence zone of planned foundations, showing susceptibility to excessive settlements. Therefore, ground improvement works were undertaken using a combination of stone columns, Rapid Impact Compaction (RIC) and excavation and replacement of soils plus a 0.4m thick load transfer platform. This was necessary to limit the settlements, increase-bearing capacity and prevent long-term settlements. 30 no’s of full-scale Zone Load Tests, ZLT were carried out each for a duration of 30 days in order to ascertain the anticipated long-term settlements in the clay layers. In addition, further testing of electrical cone penetration tests, CPT, and Plate Load Tests, PLT. The use of Priebe and Asaoka’s observational procedure were applied to predict the final settlements and the use of back-analysis from the 30 days Zone Load Tests, ZLT results to establish the site-specific consolidation parameters in clay layers to optimize the design and ground improvement works.

Sep 8, 2021