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By Andrew Budek

"Analytical and experimental work has shown that achieving the full inelastic lateral capacity of a pile may require the formation of a plastic hinge below ground level, in the pile shaft. The confining action of soil about the pile shaft was further been shown to greatly enhance the ductility capacity of the pile. An experimental program was therefore undertaken to build in the effect of external confinement through the addition of a GFRP jacket to the subgrade plastic hinge region. Two piles were thus modified, and compared to an unjacketed pile in a test rig which simulated a subgrade moment pattern and soil confinement. The ductility achieved by the jacketed piles was found to be substantially lower than an unjacketed control specimen. Failure mode of the jacketed specimens was also undesirable, involving complete tendon rupture and sudden loss in capacity IntroductionSeismic loading of concrete pile shafts can result in a demand for inelastic response. In the case of a superstructure supported by a single pile (i.e., a pile-column forming a single-column bridge pier, in which there is no rotational restraint at the top of the pile}, a plastic hinge will form below grade, at a depth which varies with soil properties and above-grade height of the center of seismic mass.In the case of a superstructure supported by multiple piles, there is rotational restraint, and the connection will experience inelastic action first. However, development of the full lateral inelastic capacity of the pile may call for the formation of a second, subgrade plastic hinge (fig. 1 )."

Jan 1, 2005

[ENGLISH active earth pressure adapter additive adhesion admixture, addition adsorbed water aggregate air air entrainment air hose allowable bearing value allowable pile bearing load]

Jan 1, 1994

By Adam Gerondale, David Hemstreet, Lisheng Shao, Kenji Yamasaki

"Foundation soils of a proposed single-span bridge over a busy railroad in Anchorage, Alaska included a layer of sensitive, non-plastic to low-plasticity silt. Slope stability analyses showed that, without ground improvement, the proposed abutments would not be stable immediately following the design earthquake due to the liquefaction of the sensitive silt. Wet soil mixing was selected to mitigate the liquefiable soils and assure abutment stability because: (i) it is a non-vibratory method and can be used for areas adjacent to the railroad tracks and underground utilities, as well as in areas not sensitive to vibration; and (ii) preand post-ground improvement testing, such as SPT or CPT, is not required. Eliminating the liquefaction hazard at the site also allowed for the abutments to be economically supported on shallow spread footings. A total of 511 soil-cement columns were constructed at the two abutments, each with a diameter of 8 feet (2.4 m) and an average length of 20 feet (6.1 m), extending from about 30 to 10 feet (9.1 to 3.0 m) below finished ground elevation. The columns were laid out in a shear wall pattern (in the longitudinal direction of the bridge) to increase stability under the loading by approach embankments.INTRODUCTIONAlaska Department of Transportation and Public Facilities (Alaska DOT&PF) is currently constructing West Dowling Road Overcrossing in Anchorage Alaska. It will be a single-span, steel box girder bridge approximately 200 feet (61 m) long and 100 feet (30 m) wide. It will have approach embankments, about 40 feet (12 m) high, on both sides. It will carry the new extension of West Dowling Road over double tracks of Alaska Railroad and Arctic Blvd. Foundation soils of the abutments consist of surficial fill and peat layer underlain by soft silt which is likely to liquefy and lose strength under shaking by a design earthquake. Both deep and shallow foundations were considered to support the bridge abutments. The design team pursued the option of improving the foundation soils and using shallow footings. Several ground improvement methods were evaluated, out of which wet soil mixing was selected as the best option.In situ wet soil mixing (hereinafter simply soil mixing) is mechanical mixing of soil in its location with cement slurry and produces soil-cement (soilcrete) columns that are stronger, less permeable, and less compressible than the original soil. Soil mixing is used for various applications including reinforcement of soft soils, excavation support, liquefaction mitigation, cutoff walls, etc. This paper presents a case history of soil mixing successfully used to improve foundation soils of bridge abutments to allow the use of spread footings."

Jan 1, 2015

By Filippo Maria Leoni, Alessandro Bertero, Gianluca Pianezze

"As part of the Southeast Louisiana (SELA) drainage program, designed by the U.S. Army Corps of Engineers (USACE) to reduce flood damages in the City of New Orleans and surrounding parishes through the construction of new pumping stations and better drainage canals, the SELA-22 project entailed the installation of a concrete covered canal along Jefferson Ave. and Prytania Street, in a highly urbanized portion of Uptown New Orleans, LA. The scope of the required soil improvement was to replace the soil between two parallel lines of sheet piles with a soil-cement mass to eliminate underseepage and provide structural support for the concrete culvert. The USACE selected the jet grouting (Jet Grout) technology for the construction of the bottom plug. The bottom plug is between 18 and 21.5 ft thick with a maximum depth of approximately 40 ft, for a total length of approximately one mile. The treated soil comprised soft clays and silts with occasional presence of sands. Project specifications required 100% area coverage, a 28-days unconfined compressive strength of 100 psi and hydraulic conductivity of 1x10-6 cm/s, to be verified by testing specimens from cored samples. The specialty geotechnical contractor proposed to accomplish the task utilizing their proprietary and innovative elliptical bi-fluid Jet Grout technology, and elected to perform a pre-construction bench scale laboratory mixing program to determine the most suitable grout mix features (i.e. binder type and proportions, binder content, etc.) to be applied in the subsequent field test and production stages. This paper will summarize and compare the results obtained from the different pre-construction and construction stages; interpretations of the data will be provided, along with general considerations regarding the effectiveness and significance of bench scale testing for jet grouting applications.INTRODUCTIONIn general, the effectiveness of the construction parameters in any ground improvement work depends largely on the physical and mechanical properties of the soil to be treated. Therefore, well designed laboratory and field test programs, aimed to disclose the interaction between the site-specific soils and the mixing parameters, are essential to achieve the desired end product."

Jan 1, 2016

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 Yoshinori Kurumada, Tatsuo Nagatsu, Keiji Uchida

"Cement deep mixing method has been utilized in the process of construction of an underwater tunnel in Singapore. The soil was improved by this method to prevent undesirable heaving of the soil below the excavated area. Quality control experiments approved the effectiveness of CDM method in increasing the strength of the soil and prevention of undesired heave of the ground. The process of the construction of this project and the quality control experiments results are discussed in this paper.INTRODUCTIONThe Marina Coastal Expressway is a 5.3 km long underwater highway tunnel with five lanes in each direction. It mostly comprises a twin box culvert structure (53.3 m exterior width and 10.89 m height) and was opened by the Land Transport Authority of Singapore (LTA).The contract zone C485 was the most challenging area of the construction; it involved a 700 m long underwater tunnel of which 400 m was built beneath the seabed at the mouth of the Singapore River. A double steel pipe sheet pile wall was built as a temporary cofferdam to keep water out of the excavation site, and the cut-and-cover method was used for excavation. In order to ensure a sufficient cross-sectional area for the flow of the Singapore River, the construction was divided into two phases focused on the left bank (Stage 1) and right bank (Stage 2).The Cement Deep Mixing (CDM) method was used to improve the ground, which comprised soft marine clay, to ensure safety during the excavation. The efficiency of this method in increasing the soil’s strength was approved previously. The design standard strength was quck = 800 kPa. Based on the study conducted after the construction, the average the Unconfined Compression Strength (UCS) of the soil stabilized by the CDM method was quf =3,000 kPa. This paper discusses the effect of the CDM soil improvement construction on the reduced displacement from the excavation and the quality control of the soil improvement."

Jan 1, 2015

By Brian McGlynn

There are many factors that can result in a site characterization being limited. For example, a client may undervalue the importance of a good geotechnical report, or an owner may feel that it would take too much time to perform an appropriate investigation among other reasons. For this project, neither was the case. The challenge was that the construction sequence of work required wick drains to accelerate the settlement of soil that had yet to be placed, resulting in the need to create a wick drain bid package based on unknown settlement parameters. This wick drain project took place in Long Beach, California, at the Long Beach Middle Harbor Re- development. For much of the past decade, the Port of Long Beach undertook a $1.5 billion redevelopment of two outdated terminals to create the Long Beach Container Terminal (LBCT). To achieve this goal, the existing terminals were demolished and the slip that serviced one of the older terminals was designed to be infilled to create the new area that would allow for the LBCT to manage 3.3 million TEUS (a commonly used freight term meaning twenty-foot equivalent unit) of cargo each year. Ultimately, the construction of the LBCT would be performed under multiple contracts to allow the new terminal to begin operation in a phased approach. Menard performed the wick drain installation under two out of three contracts, and this case history focuses on the challenges anticipated and faced under the second of these awarded contracts.

May 1, 2023

By Keith Herman, Lisa Papandrea

While New York City is known for its bedrock and being home to one of the greatest concentrations of tall buildings in the world, its soil conditions are quite variable and can be very challenging in some locations. One such neighborhood is Manhattan’s Upper East Side, particularly near East 96th Street. Historic maps show that the area was once a wetlands network of marshes and creeks. Construction projects in this area have often led to settlement of existing structures, many of which are old, low rise residential buildings supported on shallow foundations bearing on uncontrolled fill.   This case study presents the design, testing, quality control and construction of rotary-driven pipe piles for support of an 8-story medical research facility on the Upper East Side. Three hundred twenty (320) 12.75-inch diameter, rotary driven pipe piles were installed 120 feet deep. The subsurface stratigraphy consists of uncontrolled fill, organic silts, and peat over stiff, saturated, varved silts and clays. Groundwater is approximately 7 feet below grade.  The rotary-driven pipe pile does not fit neatly into any of the pile types prescribed in the NYC Building Code. Challenges were encountered developing installation criteria and a quality control program for code compliance. A “re-torque” program measuring resistance to torque and crowd-force during installation was used to verify production pile capacity and to estimate soil setup, similar to conventional driven pile restrikes.  Design methodology, torque and crowd-force measurements, load test results, and installation observations are presented. The project benefited from coordination and collaboration between the designer, contractor and special inspector during the test program and development of the final installation criteria. The rotary-driven pipe pile provides a novel “no spoils” alternative for installing deep foundations adjacent to sensitive structures. Lessons learned and potential future developments are discussed. 

Oct 7, 2024

By Roberto A. Lopez, Eric Lindquist, Jon Bussiere, Dean Iwasa

"The new 11-story U.S. Federal Courthouse building in downtown Los Angeles demanded a cost effective foundation system capable of attaining a strict total settlement criterion of 0.5 inches (12 mm) under high applied loads. A design-build ground improvement system consisting of 3 ft (0.9 m) and 7 ft (2.1 m) diameter deep soil mix (DSM) columns embedded into the relatively soft Fernando Formation bedrock was selected for the project. The DSM columns support applied stresses of up to 8,800 psf from four large concrete core elements that transfer concentrated building loads to a 3 to 6 ft (0.9 to 1.8 m) thick reinforced concrete mat. The soil mixing ground improvement solution provided flexibility by allowing installation of the DSM columns around existing belled caissons left in place from prior structures, and by allowing repositioning of some of the DSM columns to avoid other existing obstructions in the fill. DSM spoils were used to construct a 2 ft (0.6 m) thick load transfer platform on top of the DSM columns. Quality control measures included utilizing equipment outfitted with automated data acquisition systems, performing three full scale load tests, performing daily wet-mix sampling and compression testing, performing full-depth coring and unconfined compression testing on core samples, and using a borehole acoustic televiewer to evaluate the uniformity of the DSM columns where core recovery was problematic. The results of subsurface investigation and the load tests were used to develop 3-dimensional finite differences models for evaluating stress distribution and deformation of the foundation system.INTRODUCTIONThe new U.S. Federal Courthouse building is currently under construction in downtown Los Angeles, California. The new courthouse will be 11 stories tall with one partial below-grade B1 basement level. The building will have four structural core elements that extend from the main building foundation at the B1 level to the top of the structure. The majority of the building loads will be transferred through the structural core elements to a new 3 to 6 ft (0.9 to 1.8 m) thick reinforced concrete mat beneath the central portion of the structure. The foundation pressures beneath each of the core element locations will be approximately 6,200 to 8,800 psf (300 to 420 kPa) with lower foundation pressures at locations farther away from the central core area."

Jan 1, 2015

By Shoji Higashi, Nobuhiro Honda, Takeo Asanuma, Tatsuo Nagatsu, Masaki Kitazume, Sachihiko Tokunaga, Shigeru Kubo, Hidenori Takahashi, Tsuneyasu Onishi, Yoshiyuki Morikawa

"Various kinds of civil engineering structures and facilities were seriously damaged in the earthquake in Tohoku and Kanto regions of Japan on 11 March 2011 due to the greatness of its magnitude. In contrast, many structures resisted the large seismic force having been reinforced by the CDM (Cement Deep Mixing) method, which is often used for increasing the bearing capacity of ground and improving seismic performance. This paper summarizes the field survey undertaken to investigate damage to structures and facilities reinforced by the CDM method. Several prefectures and metropolitan areas were selected for the survey, based on the occurrence of strong seismic motions. A total of 847 structures and facilities were studied, in the survey using a questionnaire, which mainly inquired about the appearance of structures and facilities. Of the respondents to the questionnaire, 789 replied that there were no seriously damaged structures. The paper presents the damaged and non-damaged sites of CDM-technique sites and non-CDM-techniques sites. It can be concluded from the field survey that the CDM Method demonstrates high efficacy and durability against a strong seismic motions.INTRODUCTIONDuring the afternoon of 11 March, 2011, a huge magnitude-9.0 Mw (Category 9.0 on the Richter scale) earthquake occurred about 25 kilometers below the Pacific Ocean’s surface off the coast of Tohoku. This massive earthquake, now called the 2011 Off the Pacific Coast of Tohoku Earthquake was the largest earthquake ever observed in Japan. The seismic intensity of this earthquake was measured 7, the maximum on the Japanese intensity scale, as observed 7 in northern Miyagi Prefecture. The earthquake caused severe damage over a wide area from Tohoku to Kanto, and triggered large tsunamis that struck the Pacific coast of Hokkaido, Tohoku, and Kanto. The number of missing and fatalities caused by this earthquake exceeded 18,000 persons, making this an unparalleled earthquake disaster with a cost-in-life toll not experienced by Japan in recent years. Because of the scale of its seismic motions, the earthquake damaged facilities and structures of many kinds. In the years prior to this earthquake, the CDM method was used extensively to increase the bearing capacity of the ground as an anti-seismic countermeasure and to prevent liquefaction. Immediately after the earthquake, the CDM Association visually surveyed the state of damage to about 800 facilities in the Tohoku and Kanto regions where a seismic intensity of 5 or higher was observed. This report summarizes the survey of damage to facilities and structures constructed applying the CDM method in order to confirm the durability and performance of the method against seismic motions."

Jan 1, 2015

By Michael Shedlosky, Sonia Sorabella Swift, Nina Carney, David Tarasovic

Rigid inclusions were used to support roadway fills and mechanically stabilized earth (MSE) walls for the South Capitol Street Corridor project. The first phase of this two-phase, nearly $1 billion project will include the replacement of the Frederick Douglass Memorial Bridge, including two approach ovals east and west of the Anacostia River, the replacement of the I-295/Suitland Parkway Interchange, and the construction of several traffic ramps. The bridge itself carries over 70,000 drivers daily and is expected to open in 2021. Ground improvement is required over a portion of the project footprint. Within the ground improvement area, the construction includes MSE walls up to 35 feet high and embankment fills up to 28 feet for which CMC rigid inclusions (RIs) were used to mitigate settlement and stability. The proposed construction runs over multiple old, in-service utilities that the project requirements indicate could not tolerate any stress or settlement due to the construction. As such, solutions that spanned the utilities were required. A concrete slab of varying thickness was used to span a fragile 108-inch-diameter sewer pipeline and 48- inch-square-precast-concrete box beams were used to span twin utilities that were buried just a few feet below current working grades on site. Unreinforced RIs were used to support these structures. The center to center spacing of the RIs perpendicular to the pipe run was 26.5 ft for the concrete slab and 62 feet for the precast--concrete box beams. The axial forces on the RIs were up to 267 kips. The RIs were not structurally connected to the slab or box beams. A single-element load test was performed to confirm the load-carrying capacity of the RIs. This paper will focus on the utility protection slab over the twin utilities and provide an overview of the design of the structural and geotechnical solutions and will present the results of the load test performed. INTRODUCTION The new Frederick Douglass Memorial Bridge (FDM Bridge) and reconstruction of the Suitland Parkway/ I-295 interchange (South Capitol Project) is a part of the Anacostia Waterfront Initiative (AWI) Program, whose goal is to transform the shores of the Anacostia River. The existing FDM Bridge is approximately 70-years old and has been classified as “functionally obsolete”. The completed South Capitol Project will improve the multi-modal transportation options, increase pedestrian and vehicular safety and provide additional green space. The proposed FDM Bridge, a rendering of which is shown in Fig. 1, is designed to become a landmark bridge in the Washington, D.C. area.

Jan 1, 2019

By Abhijit Saha

"The stone columns improve the performance of foundations on soft and loose soil due to the ability of composite ground to sustain increased structural loads under reduced settlements. The interaction between the two basic elements: the ambient subsoil and installed column, present a complexity of behaviour, both in terms of applied stresses and resulting strains. Moreover, as the same is provided in-group in a regular array beneath foundations, the performance of an individual column is likely to be influenced by the presence of neighbouring columns. The present paper addresses this very issue. Analysis of reported field hydro-test data of large diameter oil storage tanks in soft ground in reference to some existing theories led to the development of the stone-column ‘group efficiency factor’. In order that such factor is of general use, it was felt necessary to examine the applicability of the factor to different sizes of groups under varied subsoil conditions. With this in view, some model test results reported in literature of single and group of columns have been analysed and in the process an explicit relationship regarding the stone-column ‘groupeffect’ could be established.INTRODUCTIONThe field application of the stone column technology has gained momentum than the intricate design methodology due to its simplicity in installation and intuitive performance. The ground improvement is due to the complex interaction within the ‘unit-cell’ comprised of the installed column in ambient ground under sustained vertical stress; in association with the interdependence of problem geometry and material properties of the two different soils-one 'native' and the other 'back-filled'. The beneficial effects are increased load capacity, reduction in total and differential settlements, minimization of post construction settlements effected by accelerating consolidation, reduced risk of soil liquefaction, aiding in improvement of slope stability of embankments and natural slopes and effecting changes in the dynamic response. The ‘unit-cell’ concept of a tributary soil cylinder encapsulating an installed column with some reasonable assumptions and boundary conditions (Aboshi et al, 1979; Balaam & Booker, 1981; Van Impe & De Beer, 1983; Priebe, 1976; Saha & De, 1994; Saha; 2005, 2006, 2007, 2011, Saha & Das; 2007) deals with the load-settlement behaviour of the composite system. The present investigation is based on published field data from literature & validated with experimental study reported in literature. The study addresses the effect of group interaction of stone columns beneath a large area loading on ground settlement. The hydrotest load-settlement data of 12 large diameter oil storage tanks founded on stone column reinforced soil at Haldia1 and Kandla2 refinery sites in India; reported by Som (1997), has been analysed to quantify the group efficiency. The results as obtained are compared with experimental study on 2, 3 and 4 stone column groups at different spacing-diameter ratios in soft clay3 reported by Rao et al (1997) to validate the above analysis. A unique relationship between the column spacing and group efficiency has been obtained."

Jan 1, 2015

By P. V. Chandramohan

"The paper deals with the arrangement of structural members for a retaining structure used as a berth in the port of Krishnapatnam. The height of retention is 24.3m. A T-shaped diaphragm wall acts as the retaining surface. A relieving platform has been provided at the top to ease lateral earth pressure on the wall. The diaphragm wall is tied back to a combination of vertical and raker pile. Later, this arrangement was altered to replace the relieving platform with just lowering of ground level below the berth. The tie back was changed to a classical A-frame anchorage. At certain reaches, installation of piles pointing towards the rear was obstructed by a conveyor structure. The anchorage was then changed to include a vertical pile and a pile that points towards the front of the berth. Change in position of inclined pile alters the force in the pile from compression to tension.GeneralPort is a major link in the multimodal transport chain. Berth is the heart of the Port infrastructure. It is here the ocean freight changes to land transport. The change-over, warrants special type of heavy duty handling equipment. The equipment and the process necessitate deep seated foundations. On one side of the berth, deep drafted ships would be berthed. But adjacent to this heavy duty cranes would be operating at the deck level. Berths are of various types. Some are founded on piles and may project into water. Some operators prefer a retaining structure. At the port of Krishnapatnam, a retaining structure was preferred. Dredged level at the berth was to be -20. Deck of the berth was at +4.3. This meant that the height of retention of soil was 24.3m. Ports are generally located near the coast. Subsoil in the port area generally consists of cohesive material of low shearing strength. The berth has to cater to imposed vertical and horizontal loads.Structural functionFor bulk cargo and containers, berth has to support the two crane tracks. These tracks will carry heavy wheel loads of the crane. Besides, the space between the tracks would be used for stacking of cargo or hatch covers. In short, the deck will be subjected to heavy surcharge. This vertical load will manifest as additional lateral force on the retaining wall. Since the height of soil to be retained is high, it is a practice to relieve the lateral earth pressure due to the heavy surcharge of the wall. This is done by providing a relieving platform. The surcharge of superimposed load on the deck and the self-weight of the soil up to a few metres below would be relieved by a suitable platform. This vertical load would be transferred directly to deeper levels through piles. Mooring pull is a horizontal force exerted by the vessel on the bollards towards water side. Berthing force is exerted by the vessel during berthing, through fenders and acts towards land side.Diaphragm walls are usually employed as the retaining face. If the height of retention is less, these walls can cantilever out but in the case of large retention, they have to be tied back. The ties are to be anchored on to suitable arrangements like a dead-man or an A-frame. Berthing structure in the early stages at Krishnapatnam port is shown in fig 1."

Jan 1, 2015

By Arash Khosravifar, Amalia Giannakou

"Nonlinear foundation springs for bridge caisson foundations show significant coupling between the shear force and bending moment. Implementing foundation stiffness matrix with coupling effects (off-diagonal components) into the global bridge model presents numerical challenges. A simplified approach is developed to model foundation springs including coupling effects using a simple methodology. This simplified model include one translational spring and one rotational spring combined with a rigid link in 2D space. Results show that nonlinear springs (translational, rotational and coupling) can be reasonably captured using this simplified procedure.INTRODUCTIONThe Izmit Bay Bridge is a 3-km long suspension bridge that crosses Izmit Bay in Turkey and is being constructed in a highly seismic region. Figure 1 shows the project location. The South Approach Viaduct (SAV), located along the western margin of Hersek peninsula, is within 5 km from the North Anatolian Fault and within a zone of secondary deformation around the primary trace of the North Anatolian Fault. The proposed SAV consists of 11 Piers and an abutment at the south end of the structure."

Jan 1, 2017

By Kazunori Matsushita, Masaru Sakakibara, Kenji Harada, Naotoshi Shinkawa, Mitsuo Nozu

The Sand Compaction Pile (SCP) method has been widely used as a typical countermeasure against liquefaction in Japan, and its effectiveness has been confirmed in many case histories of damages caused by the past large-scale earthquakes. A series of studies were conducted to evaluate the effectiveness of the compaction method and other factors, if any, in sustaining a seismic force that is greater than the assumed one and caused no damage. Based on the results of these studies, the Architectural Institute of Japan (AIJ) has indicated in its “Recommendations for Design of Ground Improvement for Building Foundations” published in 2006 that the liquefaction resistance ratio (tl/sz) of the composite ground, which consists of sand piles and surrounding compacted ground, is higher than the RL calculated by using the SPT N-values of the ground in-between the sand piles. In this paper, statistical analysis of safety factor against liquefaction, FL, was performed by using the SPT N-values of ground in Port Island and Rokko Island which were both fully reclaimed islands in Kobe city during the 1995 Hyogo-ken Nambu Earthquake (classified as intense shaking) and, together with the consideration of relative settlement, resulted in tl/sz of the composite ground being 1.5~2.5 times of tl/sz of the soil in-between piles after improvement. Furthermore, the liquefaction resistance curve of SCP-improved sites obtained from the relationship between SPT N-values and cyclic shear stress ratio during the 2011 off the Pacific Coast of Tohoku Earthquake, which was regarded as long-duration earthquake, was plotted to the left side of the curve originally proposed by Japan Road Association. Thus, the liquefaction resistance of the improved ground was found to be higher than that of the natural ground, even for the same SPT N-values, verifying the validity of the AIJ recommendation.

Jan 1, 2017

By Nozomu Kotake, Rakshya Shrestha, Ralph Griffin, Stefanos Papadopulos, Jeff Fippin, Sushil Kafle

Direct Power Compaction (DPC) is a deep Vibro-compaction method used for liquefaction mitigation. In DPC, H-beams are used as vibrating rods penetrating deep into the ground, and a vibrating force is applied directly to the tip of these H-beams to densify the loose ground. A characteristic feature of DPC is the use of a flapping plate installed at the base of the H-beam to enhance the compaction efficiency during penetration. In addition, 2-rod and 4-rod type equipment have been developed to improve productivity and enable rapid construction. DPC was selected as the most suitable and cost-effective technique to mitigate liquefaction hazards in two projects in the San Francisco Bay Area, one on Alameda Island and another on Treasure Island. Both sites were capped with hydraulically placed sand fills. Liquefaction analyses indicated excessive liquefaction-induced settlements and large lateral spread without ground improvement. Densification using DPC was performed up to depths of 42 ft to reduce the liquefaction potential of the sand fill to acceptable levels and to allow planned improvements. Cone penetration tests were conducted before and after DPC to evaluate its performance. This paper describes the equipment and process involved in DPC and discusses its application in terms of subsurface conditions and geotechnical design considerations.

Sep 8, 2021

By Roberto Nova

The selection of the Osterberg Cell (O-Cell) technology as the standard testing method for deep foundations of the Railways Po Viaduct in Northern Italy offered a relevant number of field measures on large bored pile behaviour in alluvial soils. The assessment of pile response during such ?non standard? testing procedure was performed through the comparison with standard top load tests on companion piles as well as by numerical models of the tests including a simplified pile-soil interaction scheme. As shown in this paper, the O-Cell technology allowed a careful assessment of the non-linear pile behaviour even at quite small loading levels as those required by a posteriori proof tests on production piles. Simple numerical models proved to be very effective in the simulation and the interpretation of pile behaviour during such unconventional testing procedure.

Jan 1, 2008

By Sunil S. Basarkar, Dilip M. Dewaikar, Rajesh H. Gajjar

"A load transfer program AXPILE was developed for simulation of the loadmovement characteristics of socketed piles of the Mumbai reg ion. This program used empirical relationships for ultimate shaft resistance at pile-rock interface recommended by Zhang and Einstein (1998). According to their recommendation, ultimate shaft resistance at pile-rock interface is related to the square-root of uniaxial compressive strength of intact socket material by a parameter C, which ranges from 0.4 for smooth sockets to 0.8 for rough sockets. Results of three instrumented pile load tests were compared with the AXPILE generated results. The comparison of analytical and field estimates of the unit shaft resistance confirm the recommendations of Zhang and Einstein (1998) on the unit side shear parameter c,, which was found to be in the range of 0.35 to 0.67.INTRODUCTIONInstrumented pile load tests were carried out on the test piles at the Bandra-Worli sea link project in Mumbai city of western India. High capacity socketed piles were required to take up loads from the superstructure. Hence, in addition to the available toe resistance, an accurate measurement of the shaft resistance in socket portion was desired. The instrumented load tests incorporated Osterbergcell (0-cell) assisted by strain gauge instrumentation to estimate the shaft resistance mobilization in the socket portion.AXPILE load transfer program was developed for load-movement simulation of socketed piles (Basarkar, 2004). The load transfer algorithm based on Coyle and Reese (1966) was incorporated in this program, which used empirical correlations and functions to account for load transfer in piles through shaft and toe resistance.This paper compares the computed unit shaft resistance from the AXPILE program with the measured values recorded from the instrumented pile load test."

Jan 1, 2005

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 Scott A. Walker, Gabriel J. Alcantar, Brian Zuckerman, Ramin Golesorkhi

"The stadium development consists of construction of a 68,500-seat, open-air NFL football stadium for the San Francisco 49ers. The main structure will consist of a 7-story above grade steel structure supported by over 3,000 piles. Berkel and Company Contractors, Inc. (Berkel) was selected as the design-build pile contractor who used their auger pressure grouted displacement (APGD) piles for this project. During an indicator pile installation and pile load test program, fifteen piles were tested to develop installation criteria to support demands of 150kips tension and 180 kips compression. Following the indicator pile program Berkel installed 3088 piles in 30 working days. Throughout pile installation data were collected with an automated data acquisition system (DAS). During pile installation field engineers from Treadwell & Rollo observed the pile installation as well as the real-time data from the DAS. Strategic staging and pre-production planning by Berkel along with consistent collaboration with the design team created an atmosphere for a successful and on schedule project completion.IntroductionThe new San Francisco 49ers Stadium in Santa Clara, California will be a 68,500-seat facility, a rendering of which is shown in Figure 1. The main structure will consist of a 7-story above grade steel structure supported by more than 3,000 piles. The north, east and south portions of the stadium are designed as an open seating bowl, while the western portion includes open seating at the lower levels and seven-story tower which houses over 150 suites.The stadium project includes the stadium structure, as well as elevated open pedestrian walkways, commercial community space, and three new pedestrian bridges spanning a nearby by creek. Sustainable designs and innovations such as a green roof, photovoltaic panels, a ground source geothermal system, stadium-wide Wi-Fi capability, and access to public transit are provided throughout the project. The stadium is designed as an open, light, and airy structure and is surrounded by an existing amusement park, office buildings, the Santa Clara Convention Center, and the training facility of the 49ers."

Jan 1, 2015