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By Michael Perlow Jr

A modification of the original Davisson Offset Limit (DOL) is presented for drilled foundations using soil quake (QDOL) factors ranging from 2 to 6. A further modification of the Davisson Offset Limit has also been developed using helical pile soil quake values (HDOL) based upon helix diameter. In addition, the initial tangent slope (IS) of the pile load test displacement curve is used in lieu of the calculated elastic slope (ES) to eliminate many of the uncertainties associated with determining the drilled foundation pile elastic modulus. The QDOL and HDOL load test methods do not require any graphical interpolation and provide easy simple ultimate pile capacity interpretation methods where drilled foundation pile load tests are not carried to plunging failure. Drilled foundation and helical pile load test case studies are presented to demonstrate the use of the modified soil quake QDOL and HDOL Methods.

By Han Jie

The results of full scale plate load tests on stone columns on soft clay in coastal areas are presented in this paper. Four load tests were made, two of which were performed on the ground treated with stone columns, one on an isolated stone column and the last one on the untreated ground. For a given stress range, the settlement of the rigid plate, the stress concentration factor, and the excess pore water pressure were measured. It is found that the distribution of vertical stress beneath the rigid plate supported by the composite ground of stone columns is very different in shape from the one by the untreated ground, that the stress concentration factor has a relation with the stress level and time, that the stone columns increase the bearing capacity up to by 2 times, and that the ground stabilized by stone columns is of great advantage to keep the foundation stable.

Jan 1, 1991

By Greg Nutson, Jeremy Butkovich, Bill Perkins, Hollie Ellis, Paul Bott

"Dynamic soil-structure interaction (DSSI) analyses are becoming more common in bridge designs, especially in seismically active areas. Because of its proximity to two active fault zones, the Evergreen Point west approach bridge replacement will be base isolated, and will be designed using DSSI. The project team completed two independent bridge designs to satisfy peer review requirements. The designs required substantial characterization of the soil dynamic behavior using both laboratory and in-situ testing. The analyses made use of earthquake time histories spectrally matched to conditional mean spectra. This led to reduced, and more realistic seismic demands on the structure, compared to conventional uniform hazard spectrum matching. The bridge analyses suggest that the preliminary bridge design is relatively conservative. This will allow the design team to potentially reduce shaft/column diameters and reinforcement. The design team estimates that the dynamic analysis design could represent a net savings of around $60 to $90 million compared to a conventional design.INTRODUCTIONThe Evergreen Point Bridge conveys State Route (SR) 520 2.6 miles (4.2 kilometers [km]) from Seattle to Medina across Lake Washington. The bridge is located in a seismically active area, and the Washington State Department of Transportation (WSDOT) has determined that the western half of the 1960s-era bridge (the “west approach”) is vulnerable to earthquake damage. WSDOT has begun preliminary design to replace the west approach bridge.The west approach extends about 6,100 feet (1,900 meters [m]) east from Seattle’s Montlake neighborhood, over Union Bay and Foster Island, then into Lake Washington proper (Figure 1). Approximately 5,600 feet (1,700 m) of the replacement bridge would be constructed over water. Subsurface conditions along the bridge alignment consist of 5 to 80 feet (2 to 24 m) of very soft peat and clay, over very dense/hard sand and clay. Multiple pile supported columns support the existing bridge. The new bridge would be supported by 8- to 10- foot-diameter (2.4 to 3.0 m) drilled shafts that extend about 50 feet (15 m) into the underlying very dense/hard soil. To reduce seismic demands on the bridge superstructure, WSDOT has decided to incorporate a base-isolation system into the bridge design."

Jan 1, 2017

By Tai Luu, Maxim C. Schisler, Yaser Taheri

The Stevens Gateway Project is an expansion of the Stevens Institute campus overlooking the Hudson River in Hoboken, NJ. The plans call for 90,000 ft2 (8360 m2) of new classroom, research, and student life facilities in new, 4-story buildings. The excavations for the building footprints were bounded by city streets and existing buildings, including the historic Carnegie Laboratory of Engineering, built in 1902. Pit underpinning was originally specified for the Carnegie building. However, given the depth of cut, construction time required for the 13 ft (4.9 m) deep pits would be substantial. The geotechnical contractor retained for the support of excavation work therefore offered an innovative active soil nail wall design that would meet project requirements in a shorter timeframe. Unlike the passive soil nail systems common in the industry that are chiefly used for soil slope stabilization, active soil nail walls contain pre-stressed anchor components to resist soil movement and limit settlement of soil and structures being contained. In addition to a discussion of the overall design approach of the active soil nail wall system, this paper will include a detailed description of its constructability and effectiveness. This project’s use of a conventional slope stabilization technique for an unconventional purpose may have positive implications going forward. INTRODUCTION Stevens Institute of Technology is a private university in Hoboken, New Jersey that sits on the cliffs of the City of Hoboken overlooking the Hudson River and Manhattan Island to the east of the campus. In recent years, the university has executed numerous plans to expand and upgrade its campus academic, student life, and residential facilities. One such project is the Academic Gateway Complex. The plan adds 90,000 ft2 (8360 m2) of new classroom, research, and residential facilities while also enhancing community connections by building a park to serve as a green corridor for the city. The proposed construction took place on the north and south side of 6th Street between Hudson Street and River Street. The project included the demolition of an existing university building followed by the construction of two, 4-story buildings on the north and south property lots. The north and south buildings will be connected by a second floor bridge spanning 6th Street. The buildings each contain a full basement extending from the proposed ground floor at approximately El. 41ft (12.5 m) to the basement subgrade at El. 26 ft (7.9 m). Each building will be constructed on respective mat foundations. Figure 1 presents an overview of the project area.

Jan 1, 2019

By Amr Sallam, Ahmad Mohamed, Mohamed Alrowaimi

Renewable energy, in the form of wind and solar, has emerged as main source of energy in the modern society. The wind industry has substantially grown over the last two decades to become a key player in providing energy to public. Wind turbines are getting larger, taller, and more efficient every year. The foundation is a major component of the wind turbine system. The wind turbine foundation must provide short and long-term stability for the overall turbine to allow continuous and safe turbine operation for energy production. The turbine serviceability and stability requirements must be geotechnically and structurally satisfied. In North America, major foundation types currently utilized in the wind industry include gravity spread foundation, mono pier foundation, and pile foundation. In this case study, a Post Tensioned Pile Cap (PTPC) foundation was used to support a 3.15-3.4 Megawatt turbine with 125M Rotor supported on 87.5M-hub-height tower. Soil anchors in the form of Auger-Pressure-Grouted-Displacement (APGD) piles and Continuous Flight Auger (CFA) piles were utilized. Four distinct subsoil conditions were identified, and for which four pile designs were adapted. Due to the occasional encounter of stronger soils at 50 to 55 feet (15.2 to 16.7 m), shorter pile design was preferred. To satisfy the design uplift load, pile post grouting were utilized to increase the shaft capacity of the piles. In this paper, the pre-production pile load test program will be described. The pile load test procedure, analysis, and results will be presented. A discussion will be provided, which led to the selection of the optimum pile design to support the high tension loads taking into consideration pile length limitations.

By Sven Schröer, Lilma Schimmel, Dimiter Alexiew

"The Geotextile Encased Columns (GEC) deep foundation system for embankments on soft soils was introduced some 20 years ago and is now considered State-of-the-art worldwide.The GECs consist of compacted granular fill, similar to common gravel columns, with one decisive difference: they are confined in a high-strength low-strain flexible geotextile “cylinder” (encasement). This engineered element provides a very efficient tool to control and optimize the behavior of the system. GECs perform very well even in extremely soft soils ensuring bearing capacity (stability) and reducing settlements. Due to the encasement, they a lso provide high lateral ductility. A wide range of fills including sands can be used.The remarkable reduction of vertical stresses in the soft soil surrounding the GECs results in a decrease of lateral pressure as well. Such reduction combined with the lateral ductility allow GECs to be also used for lateral pressure-relief adjacent to sensitive foundations, e.g. rigid piles. The application of GECs as lateral pressure relief was recently used in Brazil and Germany where bridge abutments were built on concrete reinforced-piles. The GECs below the bridge approaches and adjacent to the piles decreased the lateral pressure to acceptable values.This paper presents two case studies for which the most relevant parameters, the geotechnical conditions, specific problems, engineering philosophy, final solution and lessons learned are discussed. Furthermore, instrumentation programs were applied in both projects. The most important results in terms of displacements and stresses are shown, evaluated, summarized and commented upon, focusing on the lateral stress-relief, followed by conclusions and recommendations."

Jan 1, 2016

The intent of this manual is to provide guidelines for inspectors of drilled shaft construction otherwise referred to as drilled piers, caissons or bored piles. It should also be helpful to train beginning geotechnical engineers with limited first hand experience or for geotechnical engineers who are training inspectors. It is expected that the general guidelines and procedures described here will be supplemented by local geotechnical engineers working in a particular region based on local practice and experience. Since drilled shaft construction procedures vary widely based on local geology and size of project, an all-inclusive manual is not considered practical. This manual focuses on traditional topside inspection for routine drilled shaft construction. Other inspection and evaluation methods that rely on electronic equipment are available, but these methods require extensive training and experience in the interpretation of results. These more sophisticated methods of drilled shaft inspection and evaluation are common in construction, but they are usually provided by specialty subconsultants. The subconsultant will typically submit a report for each shaft, which will be reviewed by the geotechnical engineer. Other manuals are available to describe the electronic methods of drilled shaft inspection.

Jan 1, 2004

By Patrick J. Hannigan, William H. Walton, Ryan C. Rusk, Van E. Komurka

"The project consists of a 33-story building with two levels of below-grade parking across the entire building footprint. Timely and cooperative teamwork among the owner/developer, geotechnical engineer, testing agency, structural engineer, construction manager, and pile-driving contractor resulted in an efficient, costeffective, high-capacity driven-pile foundation on a constrained urban site with significantly variable subsurface conditions. Design objectives included utilizing the highest allowable pile loads reasonably installed from a drivability perspective, using readily available equipment. A pre-production test program was performed on 16-inch-diameter (406-mm-diameter) steel pipe piles, driven closed-ended and subsequently filled with concrete. The test program included dynamic monitoring of 10 piles during installation, and of select piles during long-term restrike testing with a drop hammer, with one instrumented static load test. CAPWAP® analyses were performed on both end-of-initial-drive and beginning-of-restrike dynamic test records. The site exhibited significant soil set-up, even after relatively short wait times. Testprogram objectives included characterizing set-up profiles. A design set-up profile was used to develop depth-variable driving criteria for both 500- and 600-kip (2,224- and 2,669-kN) allowable load piles. Test program results permitted more-accurate reduced capacities to be assigned to damaged piles, and to piles which experienced practical refusal. These more-accurate assigned reduced capacities decreased the number of replacement piles required by 50 percent, saving both time and cost.PROJECT DESCRIPTIONThe project, located in Milwaukee, Wisconsin, USA consists of a 33-story mixed-use residential building with two levels of below-grade parking across the entire site footprint. Column service loads range from 1,400 to 4,200 kips (6,228 to 18,683 kN). The project is located immediately adjacent to an existing two-story masonry retail building with a partial basement, supported on shallow spread-footing foundations.Subsurface Conditions – The generalized soil conditions are presented in Fig. 1. Site grades were relatively level, with a ground-surface elevation of approximately +53 feet (16 m), Milwaukee City Datum (“MCD”). Fill material from previous construction was encountered to approximate Elev. +33 feet (10 m). Below the fill, medium dense silty sand, to silt with sand, was encountered to approximate Elev. +23 feet (7 m). Underlying deposits consisted of lean clay, with undrained shear strengths ranging from approximately 1,000 to 3,000 pounds per square foot (psf) (48 to 144 kPa). Silty sand, to silt with sand, exhibiting increasing relative density with depth, was found below the lean clay to approximate Elev. -92 feet (-28 m), where hard lean clay (glacial till) with undrained shear strengths in excess of 5,000 psf (239 kPa) was encountered. Borings did not extend below Elev. -103 feet (-31 m)."

Jan 1, 2017

By Stefano Pirrello

"Sydney’s booming real estate market has pushed property developers to invest in historically “no-go” areas, which were previously too expensive to develop. These areas are usually near rivers where the sites are underlain by deep alluvial and estuarine sediments. In these ground conditions conventional bored pile techniques are often not competitive. Contiguous Flight Auger (CFA) and Drilled Displacement Piles (DD) techniques are on the other hand suitable for these ground conditions. This paper deals with the design and construction challenges encountered with these piling techniques for a series of high-rise towers in Sydney’s West. The advantages of DD over CFA piles such as reduced overall spoil with substantial cost savings and achievable rock sockets in medium strength bedrock are discussed. Design validation through interpretation of real-time data from the piling rigs’ on-board computer data, and low and high strain pile dynamic testing (PDA) is discussed. Testing data is presented as CAPWAP (Case Pile Wave Analysis Program) analyses for different concrete grades.INTRODUCTIONThe booming real estate market in Sydney has pushed property developers in investing in historically “no-go” areas, which were previously too expensive to develop. These areas are usually near rivers where the sites are underlain by deep alluvial and estuarine sediments. In these ground conditions conventional bored pile techniques are often not competitive. Contiguous Flight Auger (CFA) and Drilled Displacement (DD) Pile techniques are on the other hand suitable for these ground conditions and were utilised using concrete injection methods. This paper deals with the design and construction challenges encountered with these piling techniques for a series of high-rise towers in Sydney’s West.GEOLOGY & GEOTECHNICAL CHARACTERIZATION OF THE SITEThe Sydney 1:100 000 Geological Series Sheet shows that the site is underlain by man-placed filling and alluvial/estuarine sediment. The sediment comprises silty to peaty sand, silt and clay. Shell layers are also expected to be present within the soil profile. The Prospect/Parramatta River 1:2500 Acid Sulphate Soil Risk Map shows the site as ‘Disturbed Terrain’ in which soil investigations are required to assess acid sulphate soil potential. Several Cone Penetration Tests and Boreholes were carried out during the geotechnical investigation. All boreholes were extended to bedrock and NMLC-sized diamond core drilling was used to obtain 50mm continuous core of the rock, enabling unconfined compression strength testing to be carried out on selected samples. A summary of the ground conditions encountered on this site and inferred from the CPTs can be described as follows:"

Jan 1, 1900

By Sushant Upadhyaya, Deniz Karadeniz, Ahmed Mohamed

Soil setup analysis provides opportunities for efficiencies in pile foundation design and installation. Soil setup gain with time was evaluated as part of the foundation design and installation for twelve bridges along the Interstate 64 corridor between York County and Newport News in Virginia. The substructure elements of the bridges consist of driven precast prestressed concrete piles or H-piles. This case study describes lessons learned to understand the soil setup phenomenon during the installation of the piles in coastal plain. We were able to make expedited decisions during construction by analyzing previously performed pile dynamic analyzer (PDA) test results within the project alignment. Data evaluation included analyses of PDA data obtained from initial driving and restrike after a few hours to 5 weeks. The test data showed pile resistance increase up to twice in most cases and as high as four times in some cases. Foundation design and acceptance based on soil setup can provide opportunities for cost savings and advanced scheduling during construction.

By Keithe J. Merl, Brendan FitzPatrick, Gregg Piazza

Urban and industrial construction projects commonly involve interior work within buildings, warehouses and manufacturing facilities. Renovations of these existing structures must address both structural and geotechnical engineering challenges while also balancing the practicality of implementing solutions within site constraints including limited site access, overhead clearance restrictions, vibration tolerances and uninterrupted facility operations. This paper highlights two projects for an international shipping company where mezzanine level additions within active shipping facilities required construction of new foundations. Construction requirements included low vibration levels, as well as rapid and clean installation to limit impacts on the active shipping operations. The selected system also needed to adjust to both variable ground conditions and differing overhead clearances. This paper describes the installation, design and performance of Ductile Iron Piles used to meet the project challenges. The low vibration, driven pile system offered the ability to work within restricted overhead environments while successfully delivering working compression capacities ranging from 45 to 75 tons (41 to 68 tonnes) as well as lateral and tension resistance. The paper also presents the results of site-specific load testing (and pile capacity) for various termination criteria. INTRODUCTION Urban and industrial construction projects commonly involve interior work within buildings, warehouses and manufacturing facilities. Renovations of these existing structures must address both structural and geotechnical engineering challenges associated with the new construction. Foundation solutions must also balance the need to achieve design requirements with the practicality to be installed within the particular site constraints including limited site access, overhead clearance restrictions, vibration tolerances and uninterrupted facility operations.

Jan 1, 2019

By Sastry Putcha, Santosh Mummaneni, Swamy Avasarala, Vamshi Vemula

"This paper presents the results from a case study on the comparison of two strain acquisition instrumentation technologies, Geokon rebar strainmeters and Embedded Data Collectors (EDC) for the DC Water Main Pump Station project, in Washington D.C. These two instrumentation systems were installed by AVER in a single 18-inch (0.45 m) diameter augercast pile (with one-1.25 inch (3.175 cm) dywidag bar) at critical locations to determine the load transfer mechanism and establish a comparison between strain/load measured with these two systems along the pile. A quick static load test was performed on the test pile as per ASTM D1143 standard.Prior to the installation of the pile, a 24-inch (0.6 m) diameter outer casing was installed to the proposed cutoff elevation of -22.5 feet (-6.85 m) to discount the frictional resitance within the upper overburden zone. The pile was then drilled through the outer casing to the tip elevation of -65.02 feet (-19.8 m) with inner casing within the overburden zone. Strainmeters along with EDC were installed on dywidag bar at various locations and then wet set into the concrete following auger retrieval. The loads measured with EDC and Geokon sensors were within 15% percent of each other.PROJECT BACKGROUNDProject Background & Requirements:Like any other foundation piles, augercast piles are extensively used in the public and private sector structures in the United States for many years. It is a common practice to perform static compression (ASTM D1143), tension (ASTM D3689), and lateral load tests (ASTM D3966) depending on the project requirements. In recent years, embedded strain sensors, manufactured by Smart Structures, USA has gained prominence for its use to collect both static and dynamic measurements for driven piles. In addition, AVER has successfully used EDC for collecting long term static measurements for an abutment drilled shafts for I-95 Hotlanes project in Virginia, USA.Geokon sisterbar strain gages are widely used in the foundation industry to monitor the load transfer mechanism within pile foundations throughout the world. As the Geokon strainmeters are vibrating wire and are welded to a sister bar, there is often a debate within the engineering community with regards to what modulus to use when converting measured strains to loads. EDC sensors, unlike Geokon strain gages are embedded directly into the concrete and therefore do not have the same concern."

Jan 1, 1900

By Brian Metcalfe, Kord Wissmann, Gianni Martinez

The Middle East consists of vast deserts that reach temperatures up to 50 degrees Celsius, with some areas characterized by endless sand dunes. When the project team selected the location for a large new transportation project, little did they know that the site would be characterized by soft, nearly normally consolidated silt and clay extending below a thin sand crust. Searching for solutions, the design team elected to reinforce the subsurface with Rammed Aggregate Pier® (RAP) ground improvement elements and desired verification that the novel method would stand the test of prolonged static loads. Because the concrete pavements would serve to spread the load, a “zone load test” was performed, consisting of applying a uniform bearing pressure of 150 kPa over a 7.5m square concrete footing. Unlike individual pier load tests, the zone test allowed the project engineers the opportunity to confirm design parameter values under large-loading area conditions, a situation not often available to most designers. This paper presents the results of the zone load test whose results may be interpreted to better understand design parameter values. This paper is of particular significance because it adds a value contribution to the relatively few numbers of “group load tests” available in the literature for ground improvement applications.

May 1, 2022

By Bao K. Le, Khang T. Truong, Masaki Kitazume, Toru Kobayshi, Long P. Le, Tanaka Hitoshi, Makoto Kamimura, Hoang-Hung Tran-Nguyen

"Earth levees constructed using dredged materials taken from a river along an earth levee have annually damaged in the Mekong Delta due to high void spacing in earth levees and floodwater. Sliding and internal erosion due to floodwater or piping are two key factors causing earth levees’ failures. This study proposed to apply Deep Mixing Method (DMM) to reinforce earth levees in the Mekong Delta, Vietnam. The DMM creates a soil cement wall or soilcrete wall having better engineering properties such as higher strength and low hydraulic conductivity than those of the in-situ soils. The DMM can be applied to reinforce earth levees with limit additional materials that provinces in the Mekong Delta are difficult to supply. The study investigates capacity of the DMM to reinforce earth levees in the Mekong Delta, Vietnam against annual floods. Seepage and slope stability analyses under various conditions were performed with various scenarios of earth levee’s body. The analysis results indicate that the DMM can create a wall that cuts off piping across earth levee significantly and can improve stability against deep sliding due to rapid drawdown of the floodwater.INTRODUCTIONThe Mekong Delta produces agriculture products of 50% of the whole country even though the Mekong Delta has an agriculture area of 30% of the country (Wikipedia 2014). Rice is the main product for the domestic demand and export. This is the main reason why the local people want to cultivate rice 3 times per year to increase the total rice product for export. To do that, the local provinces have constructed earth levees surrounding each area of 100-200-hectare against annual floods to protect rice fields, and farmers can grow rice in the whole year. There are thousands of kilometers long earth levees in the Mekong Delta, and the local governments have spent millions of US dollars to repair and to maintain their earth levees yearly (reports of Dong Thap province 2012; 2014).Earth levees in the Mekong Delta have often failed in flood seasons (e.g., from August to December), especially in Dong Thap and An Giang provinces – the two provinces confronting directly the annual floods from the Mekong River when the floods reach the Vietnam land. The main failure of earth levees is piping, and then causing collapse of some section of an earth levee. An earth levee was usually constructed by piling up dredged materials along a river with minimum compaction. Subsequently, floodwater flows through connected void spacing and washes out soil particles in the body of an earth levee slowly to create piping. Annual wet-dry cycles make the top clay layer swelling and shrinking to form cracks that can store rainwater to trigger sliding (whitlow 2001; Ton That Vinh 2003)."

Jan 1, 2015

By John C. Tosh, Peter M. Kandaris, Sheldon John

Geologic, geotechnical and hydrologic studies were performed for the design of 115 deep, large diameter drilled shaft reinforced concrete foundations (6 to 12 feet) to support tall steel monopoles for a new 13-mile long 230/69kV transmission line in southwestern Arizona. The subsurface conditions along the alignment posed a wide range of challenges for performing investigation and design studies. These conditions include saturated, loose granular flood plain deposits with generally low lateral capacity, potential ground loss up to 23 feet due to occasional river flow (scour and embankment loss), liquefaction impacts from nearby active fault seismicity that can generate magnitude 6.5-7.0 earthquakes, and unsaturated alluvial and eolian sand-dominated soils to full depth with low lateral capacity. All conditions will require significantly deeper than normal foundation embedment (depth ranging from 22 to 77 feet) and will present construction difficulty due to ground instability from groundwater and dry soil sloughing. A phased investigation was performed to accurately characterize the conditions for design and construction, and included performing a review of existing data, detailed field geologic reconnaissance, a limited number of standard exploratory borings (limited access), seismic cone penetrometer soundings (SCPT) in saturated soils to better understand liquefaction and strength loss potential, and hydrologic analyses to estimate scour/ground loss potential. This paper describes the site conditions, presents details on the investigation team’s approach, documents findings in relation to deep foundation analysis and design, and discusses recommendations for foundation construction to help in reducing risk.

Sep 8, 2021

By Chandrasegaran, Tamilmani

"This paper describes a case study of a retaining wall structure using a diaphragm wall to construct a stilling basin at Tanjung Bin T4 power plant in Johor Bahru, Malaysia. The stilling basin is part of the Phase IV (T4) 1x1000MW power plant’s offshore cooling water discharge culverts. The site is located close to the sea with 5m of fill on top of very soft sediments of marine origin up to 20m thick underlain by fluvial clay and metasedimentary rock. Stringent wall deflection criteria and construction program dictated adopting an efficient solution with 800mm thick diaphragm wall supported by permanent top support as the temporary prop and improved horizontal restraint provided by deep mix piles acting as a slab (ground improvement layer) below the final excavation level. The depth of excavation is about 10.12m from the existing ground level. The proposed solution kept the wall deflection below the limit of 0.7% of the depth of bulk excavation and avoided additional props leading to faster completion of the structure. With unsymmetrical loading behind the retaining walls, 2D finite element analysis was carried out to assess the wall deflection and stresses in the wall and the grout layer below. The diaphragm wall is instrumented to monitor the behavior and the findings are discussed in the paper.INTRODUCTIONConstruction in soft marine clay has always been a challenge to the engineer because of its very low shear strength and its sensitivity to disturbance. In the case of excavation projects the problem becomes even more complicated with development of excess pore pressure during excavation. Marine clay with its low shear strength and lesser passive resistance, generally leads to large wall movements and settlement behind the wall. Increased passive resistance coming from increased number of props is useful but has its limits and it is no longer the most effective way in containing or reducing the wall movements or forces in the wall. One of the solutions to these problems is to improve the soil shear strength by means of ground improvement infront of the wall at an elevation most appropriate to maximize wall performance. There are several methods adopted in improving a soil layer including mixing additives to the ground to improve the shear strength to partially replacing the weak soil while others are fully replacing the weak soil. This paper discusses the case study of approximately 10m of excavation in soft marine clay using 800mm thick diaphragm wall supported by Deep Mix Piles (DMP) being used to improve soft marine deposit to form a slab just below the formation level and thus improving passive resistance significantly. The ground improvement layer helped to reduce the wall forces and deflections making it possible to remove the need for additional temporary props leading to significant savings is time and productivity. The paper presents the various options explored before this method is adopted, the design approach, instrumentation data and the monitored results."

Jan 1, 2015

By Janaka J. Kumara, Takashi Kurashina, Yoshiaki Kikuchi, Takahiro Yajima

"The inner frictional resistance of open-ended piles depend heavily on the degree of soil plugging. Many factors including pile diameter, relative density and end conditions of the piles influence the degree of soil plugging. In this paper, the effects of inner sleeves attached at the pile base on the inner frictional resistance are discussed. The experiments were conducted on a medium-dense sandy ground using smallscale model piles. The results suggest that the inner frictional resistance is influenced by sleeve height for 50 mm diameter piles although it is independent for 30 mm diameter piles. The results also indicate that soil plug height is influenced by the sleeve height. The results of the incremental filling ratio (IFR) showed that penetration of non-sleeved piles is closer to unplugged state than the sleeved piles. The results of the IFR also reveal that the degree of soil plugging is affected by the sleeve height for 50 mm diameter piles although the variation is very limited in 30 mm diameter piles. The results on the coefficient of lateral earth pressure suggested that it increases from 1.08 – 1.75 when the sleeve height is increased from 10 – 100 mm for 50 mm diameter piles.INTRODUCTIONPrevious studies have shown that the behaviour of open-ended piles is different from closed-ended piles (Szechy, 1961; Randolph et al., 1979; Paikowsky and Whitman, 1990). Open-ended driven piles are widely used for deep foundations, in particular in offshore deep foundations. Generally, it is accepted that a short open-ended pile produces a smaller bearing capacity than a similar closed-ended pile (Nauroy and Tirant, 1983). However, a long open-ended pile can produce a similar bearing capacity as a closed-ended pile due to a large inner frictional resistance mobilised between the inner pile shaft and inner soil (Lehane and Randolph, 2002). The ultimate bearing capacity of an open-ended pile, Qu consists of three components as given in Eq. 1."

Jan 1, 2017

By Andres M. Baquerizo, Jeremiah J. Filjones, Nicholas Feldt

The Estates at Acqualina located in Sunny Isles Beach, FL, is comprised of two, ocean-front, 50-story, luxury towers with podiums and villas. With city regulations now requesting that above-grade floors be limited to commercial or residential units, parking facilities for the tower structures were situated within two levels of underground basement parking. However, ensuring dry excavation through south Florida’s highly pervious limestone, immediately adjacent to the beach where the groundwater table is very shallow, can be extremely challenging and costly for developers. In recent years, significant advances have been made to overcome this challenge with the innovative use of deep soil mixing to create a “dry hole”, assisting in the construction of foundations and underground usable space for parking, storage, etc. The “dry hole” system includes a soil mix bottom seal, with soil mix secant pile walls in combination with auger cast deep foundation elements to support the future structure. This approach enables groundwater control to greater depths than can be achieved by conventional sheetpiling and dewatering. For the Estates at Acqualina, a successful turnkey, design-build joint venture between two foundation and geotechnical contractors resulted in a dry excavation to 34 ft (10.4 m) below grade and to a record- breaking auger cast pile depth of 182.3ft (55.6 m), all within an aggressive 26-week schedule to deliver the “dry hole” excavation for the first tower. This presentation will discuss the logistics, quality control, design, and safety for the different techniques involved. INTRODUCTION AND BACKGROUND The Estates of Acqualina is a pair of 50-story luxury towers located on Sunny Isles Beach in Florida with a two-level underground basement for parking. The project’s location just steps away from the Atlantic Ocean, geology, and high-water table created a challenging project. The owner, Trump Group, contracted the joint venture of HJ Foundation and Hayward Baker (HJ/HB) to design-assist-build a system to control the groundwater, allowing the 2-story underground parking structure to be constructed. In order to accomplish this task, the JV utilized an installation technique known as deep soil mixing. This technique mixes the in situ material with a cement slurry to create a very impermeable material called “soilcrete”.

Jan 1, 2019

By James R. Gingery, Byron Foster, Bret Lingwall

While microzonation and setbacks are the typical mitigation for structures exposed to surface fault rupture hazards, lifelines and lifeline facilities are not easily relocated to avoid faulting. In these cases, other remedial measures including ground improvement may be warranted. Deep soil mixing ground improvement was used in this case to mitigate surface fault rupture and liquefaction hazards for a pump station at a wastewater treatment plant with wet wells up to 36-feet (11-m) deep. Paleoseismic field investigations were performed to characterize the site, then deterministic and probabilistic fault rupture displacement estimates were made and used to develop design scenarios. The fault rupture mitigation design consisted of a solid block of DSM encompassing and protecting the pump station and its wet wells. Three dimensional soil-structure interaction numerical modeling of the fault rupture scenarios was performed as part of the design. The analyses showed the fault rupture displacements could be diverted by the DSM and that satisfactory structure performance could be achieved. The design required construction of a large 100 percent replacement ratio block of DSM with a compressive strength of 500 psi. Aspects of construction of this DSM block are discussed.

Sep 8, 2021

By Xiaocen Lu, Guowei Li, Jiantao Wu, Thang N. Nguyen, Andrew C. Amenuvor

"This paper investigates the effect of driving a group of 52 open-ended Prestressed High Strength Concrete (PHC) piles on an existing highway embankment based on field measurements of excess pore pressure and lateral soil displacement. Excess pore pressure due to pile driving increased with depth and decreased with increasing distance from the pile, influencing a distance of 43 pile diameters. For pile groups, the rate of dissipation of excess pore pressure decreased with increasing depth and averaged 79% in 20 days, during which maximum ultimate bearing capacity was not yet attained. Lateral soil displacement continued to increase for a period of time after the end of pile driving and this could have resulted in significant inclination of piles if pile installation was too quick and pile spacing was too small. Lateral soil displacement due to pile group decreased with decreasing distance to the existing embankment as a result of high soil density produced by the embankment loading. The results also indicate that the effect of pile group installation on the existing embankment is negligible.INTRODUCTIONPile driving can cause excessive lateral displacement of soil and heaving of the ground surface, which may adversely affect nearby structures. In addition, lateral deformation and excess pore water pressure resulting from pile driving can exert lateral pressures and vertical forces on the piles, and impact negatively on the project and its surroundings. Therefore, it is important to evaluate the influence of pile driving on the nearby structures as well as the project itself when expansion works are carried out.Recent years have seen some development in the application of field tests for studying soil disturbance due to piles, and these tests usually involves pore water pressure and lateral soil displacement monitoring during pile driving. Results of field experiments performed by Reese and Seed (1957) in San Francisco Bay Mud with instrumented piles showed that pile installation generated large pore water pressures at the pile surface, with only slight increase at a distance of 15 pile diameters away. The measurements indicated that the increase in pore water pressures can exceed the initial total overburden pressure. Holtz and Lowitz (1965) reported a decrease in undrained shear strength immediately after pile installation, which was largely recovered after full pore pressure dissipation for field measurements within 1.5–2 pile diameters from the pile surface. Hwang et al. (2001) presented results of large scale pile driving tests where maximum excess pore water pressure generated decreased rapidly with increasing distance from pile. The excess pore water pressure became negligible at 15 pile diameters from the pile. Their results also showed that lateral displacement of the ground decreased with increasing distance from the pile. Pestana et al. (2002) carried out full-scale closed ended pile tests in the Young Bay Mud deposit. Higher excess pore pressures were observed for points closer to the pile, which decreased with increasing distance from the pile wall. Exponential decay of excess pore pressure with time was also noted. An 80% dissipation of excess pore pressure was achieved for soils more than one pile diameter away from the pile wall between 50 to 80 days. Lateral deformation generally decreased with increasing distance from pile wall, whilst varying erratically with depth. Bozozuk et al. (1978) reported on soil disturbance due to driving of 116 concrete piles in sensitive marine clays in a construction project. Maximum pore water pressures after pile driving within the group, and 6m (20 pile diameters) from the group were over 35-40% of the total overburden pressures, and the influence of pile driving on pore water pressure at 20m away from the group was very small. Cooke and Price (1973) studied a 168-mm-diameter instrumented pile jacked into over consolidated London clay. Outward lateral displacements ranging"

Jan 1, 2016