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By James F. Davis, Matthew A. Conte, Robert F. Tonning

This is a paper demonstrating the steps taken to combine multiple types of piles for a single site to maximize the benefits and characteristics of each method. We intend to discuss the use of grouted displacement piles in lieu of traditional pile types that were specified on an individual project. We will show how implementing this alternate pile type can both supplement and replace the originally specified pile to increase efficiency and lower costs. We will demonstrate a reduction in spoils, vibration, crew hours, and equipment size while employing methods to overcome unforeseen ground conditions.

By Alexandra Weidle, Seffen Leppla, Rolf Katzenbach, Matthias Seip

"A lot of different deep mixing systems have been developed in the last decades for a wide spectrum of applications, e.g. retaining and foundations systems, soil improvement, sealing of toxic substances or dyke strengthening. The paper will deal with special aspects of constructions with deep mixing systems for infrastructures like soil improvement for cyclic loadings and underpinnings in difficult soil conditions by presenting cases from engineering practice.1. DEEP DRY SOIL MIXING FOR SOIL IMPROVEMENT OF RAILWAY TRACKS IN VERY SOFT SOILS1.1 IntroductionRailway tracks are set into vibrations by train passing. In very soft soil this leads to long-term deformations which lead to speed limits, temporary closings and big maintenance efforts. The energy of the dynamic loading is transmitted into the soil by compression and shear waves and at the surface by rayleigh waves (Wood 1968). The expansion of the waves are influenced by•,thickness of the soft soil layer•,density of the soft soil layer•,stiffness of the soft soil layer•,saturation of the soft soil layer•,frequency of the dynamic loadingThe frequency of the dynamic loading depends on the train velocity and the distance of the wheels and wheel sets. If the frequency of the dynamic loading is in the range of the natural frequency of the soft soil layer the vibrations increase extremely (Lieberenz et al. 2003). As a result the long-term deformations will increase as well.To avoid these long-term deformations and the resulting operation restrictions and maintenance efforts an adequate soil improvement is necessary. For the optimization of the soil improvement field tests have been carried out.1.2 Experimental field testsThe field tests have been carried out at a 300 m long test track with five different setups, each 30 m long:•,test track TS 0: no soil improvement•,test track TS 1: soil improvement with single lime-cement-columns 5.9 m deep (Figure 1a)•,test track TS 2: soil improvement with single lime-cement-columns 5.9 m and 10.4 m deep (Figure 1b)"

Jan 1, 2015

By Hidekatsu Takeuchi, Masaru Sakakibara, Shigeo Tanabe, Kenji Harada, Akihiko Suzuki, Shoji Morihana

"Deep mixing (DM) method, one of the most commonly used solidification methods, is based on the principle of solidifying soft ground. It can be classified into two categories such as Cement Deep Mixing (CDM) method and Dry Jet Mixing (DJM) method which apply hardening agent in slurry condition and in powdery condition respectively. In recent years, DM methods have undergone changes that have evolved them from the traditional method to meet the needs of the diversifying market. Among them, the Contrivance-Innovation Clay Mixing Consolidation (CI-CMC) method is a DM method which mixes a cement-type hardening agent in slurry condition mechanically with soils in situ and incorporates the innovative technique, “atomized ejection” that has been developed to allow faster installation of larger diameter columns without sacrificing quality compared with conventional methods. At this technique, the atomized hardening agent is discharged together with compressed air through a device incorporated into the mixing blade. It also has advantages of performing the works with low-displacement of the surrounding soils in consideration of environmental friendliness and with higher penetration capability against hard ground.This paper presents the technological outline of the above-mentioned CI-CMC method, focusing on the atomized-ejection technique, followed by some construction examples, applied to the self-earth-retaining wall, to the hard ground and the area adjacent to the existing structures.INTRODUCTIONAccording to the accumulation of its case histories, Deep Mixing method has been receiving the demands of its application to more challenging conditions, such as harder ground condition, and requirement of lower displacement of the surrounding ground during its operation. In addition, to match its price against the other cheaper methods and widely receive its benefit of higher quality, the cost reduction of Deep Mixing is also one of the major challenges. For the cost reduction, higher productivity and lower consumption of the material to obtain the equivalent strength and homogeneity with the conventional method are required.The Contrivance-Innovation Clay Mixing Consolidation (CI-CMC) method has been developed to meet these demands. CI-CMC incorporates the mist ejection that has been developed to achieve faster installation of larger diameter columns without sacrificing quality compared with the existing methods. Normally, we obtain cement columns of about 1.0 m in diameter by using Deep Mixing method. To increase the productivity, it is not preferable to drastically increase the penetration and withdrawal speed of the mixing blades because of the hardness of the ground and restriction by minimum number of passage of rotating blades per a certain height of the soil cement. Instead, the expansion of diameter of the columns will simply increase the productivity. The development of the new mist ejection system, as shown in Photo 1, has enabled the diameter of soil cement columns to 2.0 m on single axis while 1.6 m on double axes. Mist ejection means that the hardening agent slurry is sprayed into the ground in mist form together with compressed air thereby achieving homogeneous mixing and reducing the resistance on rotating blades."

Jan 1, 2015

By Kenneth R. Chadwick, Thomas J. Tuozzolo, Terence P. Holman

"Micropiles are often installed to retrofit existing foundations that experience distortion and to underpin structures prior to future construction. The Dublin Road Pump Station project is an example of retrofitting due to a basal failure during construction that compromised the bearing capacity of the soils. A completed pump station settled and had to be restored to its original position, and work could not proceed until a new support system for the partially completed wet well could be designed and installed. The project involved the construction of three below-grade structures for a new pump station in a growing area of Jackson Township, N.J. The general contractor constructed three pump station structures consisting of a pump chamber, wet well and an inlet chamber in early 2006.The geologic conditions beneath the project site (Figure 1) consisted of loose/soft to medium dense/stiff sand, silt and clay to a depth of 40 ft below ground surface, underlain by medium dense to dense glauconitic silty fi ne sand. When the general contractor was constructing the wet well, which involved an internally supported sheet pile excavation 32 ft below the ground surface and 28 ft below the static groundwater level, basal failure, boils and ground loss occurred. Driven piles were installed to support the wet well structure, but additional ground loss was observed within and outside the sheet pile excavation, followed by settlement of the adjacent pump chamber structure. Post-failure investigations were conducted by Mueser Rutledge Consulting Engineers, N.Y. (MRCE), a geotechnical and foundation engineering consultant. Their investigation concluded that the ground losses around the pump station structures had compromised the supportive capabilities of the natural subsoils.The owner engaged Moretrench, a geotechnical specialty contractor, to work with MRCE to develop a constructible solution to support the pump station structures in general and to restore the pump chamber to its original position. Knowing that ground loss had already occurred as a function of the initial basal heave and subsequent pile driving, the team selected micropiles as the preferred foundation element, primarily due to their flexibility in bypassing these disturbed zones and generating capacity as a function of grouting volume and pressure. Drilled piles were also recommended due to concerns about causing additional settlement of the pump chamber if driven piles were used."

Jan 1, 2008

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 Jewels Stover, Charles A. Luxford

Oklahoma City is undergoing a replacement program for an existing 66in (1.675m) water pipeline that conveys raw water from Atoka Reservoir to the City. This pipeline currently crosses the Canadian River on elevated piers and is subject to flood hazards. To replace the existing pipeline and mitigate flood damage concerns, two parallel microtunnels will be constructed below the river channel. Access is from construction shafts located near the midpoint of the tunnels; opposing drives are launched from each shaft. This geometry dictated shafts of significant depth – exceeding 120 ft. (37m). To accommodate the casing pipe segments and microtunneling machines, a minimum shaft diameter of approximately 34 ft. (10.4m) was required. Due to the difficult geologic setting, a reinforced secant pile compression ring is specified by contract in the top 70 ft. (21.3m) of these construction shafts to provide a very low permeability support system.

Sep 8, 2021

By Thomas D. Humbert, Christopher J. Ramsey

Construction of a new underground parking structure in State College, Pennsylvania, is situated on a site constrained by limited ROW and required excavations ranging in depth from 25 ft to 40 ft. Additional complications included busy surface streets, an active intersection, and numerous underground utilities that could not be disrupted by construction activities. To combat these challenges, an innovative approach for earth retention was designed that combined multiple types of retention systems. The overall system included alternating sections of soil nail walls and a hybrid system of soldier pile walls (consisting of micropiles) that were partially restrained by a soil nail wall in the lower portions of the excavation. Further, due to the limited space within the property limits that inhibited the length of the permanent nails, the wall design team collaborated with the project designers to develop a solution such that the completed wall became an integral part of the final design/construction of the underground parking structure. INTRODUCTION HERE at State College is a mixed-use, high-rise building in State College, Pennsylvania. The 12-strory building has up to 3 levels of below-grade parking, with the above-grade levels consisting of residential and commercial/retail space. The existing property was a parking lot bound by the streets Calder Way to the north, Garner Street to the east, East Beaver Avenue to the south, and Heister Street to the west. The overall property sloped approximately 20 ft in elevation from southeast to northwest. Excavation for the below-grade levels extended 21 ft to 36 ft (6.4 m to 11 m) below street level. During design-development phases of the project, it became evident that due to subsurface conditions and right-of- way limitations, conventional construction techniques would not be feasible. The full perimeter of the excavation would require earth retention including the weak shale bedrock along the bottom of the excavation. The project developer (CA Ventures) and general contractor (Brinkmann) coordinated with the specialty contractor and wall design engineer to find a solution. At this time, Coastal Drilling East (specialty contractor) and Wood Environment & Infrastructure Solutions (wall design engineer) became involved. The project developer and general contractor were aware they needed an earth retention system, but given the many variables the project faced, a single, straightforward solution would not work in this application.

Jan 1, 2019

By David S. Graham, Paul J. Axtell

Crosshole Sonic Logging (CSL) non-destructive integrity testing identified anomalous readings near the base of a 6.5-foot diameter drilled shaft rock socket. The anomaly was confirmed to be a defect by subsequent coring and core hole camera inspection. A large void and exposed rebar were visually observed in one of the core hole camera inspections. The center of the shaft was then excavated initially with 3-foot diameter tooling and subsequently with 4-foot diameter tooling as part of the remedial actions to address the defect. While excavating with 3-foot diameter tooling, the shaft defect was not encountered. Excavation with 4-foot diameter tooling revealed the defect, a significant void around the majority of the shaft circumference. The void extended radially from the circumference of the 4-foot diameter excavation to beyond the reinforcement cage to the exposed wall of the rock socket around approximately 80 percent of the shaft circumference. CSL results and observations made during remedial shaft investigation and excavation are in good agreement. The shaft defect, located primarily outside of the reinforcement cage, was effectively identified by CSL testing. Although the defect was confirmed by investigative coring, the remedial excavation demonstrates how the investigative coring could have easily missed the defect. This paper shows how CSL results compare to physical observations made during a rare opportunity to characterize the full extent and nature of a drilled shaft defect originally identified as an anomaly by CSL testing. INTRODUCTION The case history presented here pertains to a drilled shaft for a multi-shaft bridge pier in the Midwestern United States. However, the observations presented in this paper are not a result of unique site conditions or the particulars of the project. The lessons learned from this case history are applicable to almost any drilled shaft constructed in the wet. The overall length of the subject shaft is 22 feet including approximately 12 feet of permanently cased, 7-foot diameter shaft extending to bedrock and approximately 10 feet of uncased, 6.5-foot diameter rock socket. The shaft is designed to resist axial and lateral loads and considers the contributions of side and base resistance in the axial design. Six, 2-inch diameter steel Crosshole Sonic Logging (CSL) tubes are include in the shaft. The bedrock at the shaft location includes beds of sandstone, shale, and limestone. The shaft was drilled using conventional drilling equipment and tooling, and water was used as the drilling fluid. Conventional drilled shaft concrete appropriate for underwater tremie-placement was placed via a 10-inch diameter open hopper tremie.

Jan 1, 2019

By Mehih Demirkan, Kevin Tehansky

Located about an hour drive south from Washington, D.C., the Maryland Transportation Authority (MDTA) contracted with Skanska-Corman-McLean (SCM) to deliver a new Governor Harry W. Nice Memorial/Senator Thomas "Mac" Middleton Bridge, which takes U.S. 301 over the Potomac River, spanning 1.9 mi (3 km) from Maryland to Virginia. The new bridge aimed to improve capacity, safety and access of the roadway and was planned as a four-lane span with deep foundations that would be constructed fewer than 150 ft (45 m) north of the existing alignment of the more than 80-year-old bridge. The new Harry Nice Bridge opened in the fall of 2022 with a design life of more than 100 years, servicing 12 ft (4 m) wide lanes with 2 ft (0.6m) shoulders, doubling capacity, enhancing emergency response, upgrading maintenance and inspection activity access, and featuring lane sharing for cyclists.

Apr 1, 2023

By Jørn Thomsen, Christoffer Brodbaek

"As governments increasingly accord high priority to sustainable energy, policymakers are finding that wind energy has a long track record as a proven alternative to conventional energy supply.Over the past two decades, wind turbine projects have been constructed offshore because of more stable offshore wind conditions and because there is more available space for large wind farms out in the open sea. Vindeby Wind Farm in southern Denmark was constructed in 1991. As the world’s first offshore wind farm, it provided valuable information and experience for researchers and designers that have led to new technologies and design improvements, a trend that will continue as more offshore wind farms are constructed. Today, the world’s capacity of the installed offshore wind turbines exceeds 1,000 MW. Most of these are installed in Northern Europe where there was early political support and favorable conditions, such as strong winds and relatively shallow waters. Offshore wind projects are now under development around the globe, including continental Europe, the U.K. and North America. ‘The largest offshore wind farm today is Denmark’s Nysted Offshore Wind Farm, which has a total capacity of approximately 480,000 MWh, equivalent to the yearly consumption of 120,000 households. It is five to six miles offshore in the Baltic Sea in the southern part of Denmark.The owner is a joint venture between DONG Energy of Denmark and E.ON Sweden. Bonus Energy (now Siemens) supplied the wind turbines, and P. Aarsleff A/S and subcontractors supplied the foundations. The contractor’s consultant, COWI A/S of Denmark, developed and designed the turbine foundations. With a total capacity of 165.6 MW, the project consists of 72 Bonus 2.3 MW turbines in water depths up to 33 ft. The turbines have a hub height of 226 ft, and the turbine blade diameter is 270 ft. The rotor and nacelle (the structure that houses the generator, gearbox and other equipment) weigh approximately 150 tons, and the weight of the steel tower is approximately 130 tons. The wind farm site is located in a relatively protected area of the Baltic Sea, but during the winter months, the water often freezes and the foundations needed to be constructed to resist ice forces. The founding soils at the site are overconsolidated clay tills with boulders and with a thin layer of softer surface sediments. Pockets of up to 30 ft of soft sediments were encountered, which required special foundation preparations."

Jan 1, 2009

By Jeongbok Seo

The Dulles Corridor Metrorail Project (DCMP) involves the design and construction of a 23.1-mile extension of the Washington Metropolitan Area Transit Authority (WMATA) rail system. The initial 11.7-mile extension, with five transit stations and a new service and inspection yard, is to be constructed. The construction plan for the initial 11.7-mile extension includes installation of a total of an estimated 4,250 or 160,000 linear feet of driven 12x53 steel H-Piles at more than 80 different locations. At the time of this paper, approximately 40 percent of the piles have been installed and the remainder of piles will be installed by the end of 2010. This paper describes: 1) subsurface investigation program, 2) application of existing Codes and impact on the design of H-Pile, 3) design methods to determine geotechnical bearing capacity and pile tip elevation, 4) verification of capacity including PDA and Static Load Tests, 5) project specific pile load tests, and 6) QA/QC during pile driving.

Jan 1, 2010

"Full time inspection of drilled shafts by qualified personnel is a necessary part of construction. Detailed inspection procedures for routine inspection are provided in the Drilled Shaft Inspector’s Manual, published jointly by the DFI and ADSC: the International Association of Drilled Shaft Contractors.The use of NDT methods or other observation methods, such as probes, video camera inspection, remote shaft wall inspection devices or various calipers are not suitable substitutes for routine "topside" construction inspection as described in the Drilled Shaft Inspector’s Manual. However, these NDT and other "remote" or indirect observation methods are valuable alternatives to direct entry of personnel into drilled shaft excavations. They should be considered whenever appropriate to reduce the risks of direct entry of personnel into drilled shaft excavations.As described in the Drilled Shaft Inspector’s Manual, observations made during construction are essential for quality construction of drilled shafts. The shaft depth, diameter, plumbness, bottom conditions, reinforcement, concrete continuity, and bearing conditions are most easily checked during construction. Some of these observation methods include excavation around the shaft for relatively shallow inspection, down-hole inspection for end bearing conditions or rock sockets, and video camera devices for remote inspection. In rare circumstances, a drilled shaft can be extracted for inspection. Before concrete placement, the bottom of the shaft can also be probed by drilling or coring to determine if there are voids or soft zones in the material at the base of the shaft.The Drilled Shaft Inspector’s Manual focuses on traditional "topside" inspection for routine drilled shaft construction."

Jan 1, 2004

By Ronnie W. Sisk

1. Troubles start early - Inadequate Geotechnical Data A. Owners think they are saving money by allowing limited soil borings at their site. This places a high gamble on the bidders and the Lump Sum Price will be higher. B. Inaccurate elevations on soil reports. a. Surprises in depths - over or under design bid bottom elevations. 1. Requires backfill and extraction of casing that is too short for the greater depth of the drilled shaft. 2. Redrill utilizing longer casings. 3. Softer earth (backfill) can cause difficulties in redrilling such as less quantity extracted on the auger and maintaining plumbness. 4. Greater concrete overrun. b. Extreme under depths. 1. Excessive concrete is placed as a result of planning for a deeper shaft. c. Geotechnical report that does not supply a layout of boring locations. d. Design Engineer does not have a basic knowledge of how a caisson is installed.

Jan 1, 1988

By Joe Harris

Large structures, such as a multistory office building or a large storage tank, are constructed the most economical way possible, which may involve a shallow foundation system placed on native soil or compacted fill material. Over the life of the structure, the foundation system may not perform as originally anticipated, leading to differential settlement. Minor differ- ential settlement is expected; however, settlement that exceeds allotted tolerance can render the structure inoperable. Compaction grouting is a well-known and accepted ground improvement technique that can be used to not only stabilize but relevel multistory buildings and large dia- meter storage tanks. Two projects, each with differing types of structures, were successfully remediated utilizing com- paction grouting as the primary method to remedy settlement.

Sep 1, 2023

By Tom George

"INTRODUCTIONNo. 1 Queens Rd was an existing 10-storey office building founded on large pad footings. This project involved the construction of a 6-level, 15m (50-ft.) deep basement excavated immediately adjacent to the existing building and also beneath the existing footprint of the Southern end of the building. The total perimeter of the new basement was to be approximately 200m (656 ft.) all with a retained height of 15m (50 ft.). It was also proposed to add a further 5 storeys to the building. Approximately 18 of the existing columns supporting the 10-storey building were to have the applied column load diverted from the existing foundations at ground level onto the new piles or basement raft 15m (50 ft.) below.The geotechnical profile consisted of fill for the top 1.5m predominately comprising of clayey sand with a high gravel content from 1.5m to 9m (5 to 30 ft.), a medium dense to dense clayey sand and then below was a sandy clay extending to 15m (50 ft.) ranging from stiff to very stiff. From 15m on completely to extremely weathered siltstone was encountered. The groundwater was measured at 9.5m (31 ft.) below the natural ground surface.DESIGN BRIEFThe existing building columns were founded on large pad foundations up to 4.4m (14.5 ft.) square, founded on the dense clayey sand. These pads would require temporary support to enable the excavation to proceed beneath them. Upon completion of the excavation under the pads new columns were to be constructed joining into the existing columns to transfer the load onto the new raft slab, 15m (50 ft.) below. The existing 10 floors were to be refurbished. It was planned to undertake all the temporary support and transferring of loads while the structure above was only able to provide a dead load. It was decided that any movement of the building would have minimum impact on a skeleton structure. During the temporary support of the columns, movements due to construction activities had to be monitored to understand any potential stresses in the structure above.The original design required beams to be installed under the pads and supported at either end by temporary piles that were to be founded below the level of the proposed excavation. (Refer to sketch 1). Wagstaff Piling considered that this methodology had difficulties in construction at all stages and did not provide facility for transfer of the load without significant movement of the structure above. Wagstaff Piling revised the design to attach beams to the columns above the pads using shear collars. (Refer to sketch 2). These beams supported on the temporary piles could then be jacked upwards to remove loads off the pads. This would enable removal of the pads with minimal movement of the 10-storey building above. (Refer to photo 1 and back cover photo)."

Jan 1, 2005

By Todd W. Armstrong, Michael D. Reader

"INTRODUCTIONThe Playa Vista Development is the largest urban infill development in the history of the United States. Overall, it encompasses about 1100 acres in the City of Los Angeles and is situated north of Los Angeles International Airport near the Pacific Ocean. The development taking place on the project consists primarily of high-density residential condominiums with 1 to 2 levels of subterranean parking . The geotechnical conditions are typified by high groundwater, soft clays, and liquefaction, in addition to environmental issues such as methane.Due to a combination of the geotechnical factors and noise restrictions, both driven and drilled piles were not feasible once the initial phase of the project was occupied. As a result, the project developer undertook a testing program that consisted of the installation and load testing of 9 piles in order to obtain City of Los Angeles acceptance of a pile installation system that met the site constraints. The testing program was divided between two separate contractors operating on sites set on opposite sides on the street (Figure 1 ). Contractors working in Test Areas A & B employed the ""dry dip"" and ""wet dip"" methods of auger pressure grouted displacement (APGD) pile installation, respectively.This paper summarizes the extraordinary program undertaken to install, document, test, and examine auger pressure grouted displacement piles at this site. The program ultimately resulted in City acceptance of auger pressure grouted displacement piles, a historically difficult challenge given the City's resistance of acceptance of ""new"" technologies.A summary of elements included in the test program are: (1) quality control; (2) load testing; (3) long-term testing; (4) non-destructive testing; and (5) pile exhumation."

Jan 1, 2005

By J. Hamada, K. Yamashita, Y. Shigeno, T. Tanikawa

"This paper offers a case history of piled raft foundation in soft ground supporting a twelve-story building in Tokyo. To increase bearing capacity of the soft soil as well as a countermeasure of liquefaction, grid-form deep cement mixing walls (DMWs) were employed with the piled raft. Based on the long-term monitoring results, the ratio of the load carried by the DMWs to the effective structure load after the construction of the raft was estimated to be 0.3 while that carried by the piles was 0.7. In order to clarify the contribution of the DMWs to bearing the structure load, numerical simulation of the settlement and the load sharing among the piles, the DMWs and the unstabilized soil was performed using a three-dimensional finite element model. The results of the numerical simulation agreed well with the measured values, when the Young’s modulus of the DMWs obtained from the unconfined compressive tests was adopted and the shear modulus of the soft soil was reduced to 50% of that at small strains.INTRODUCTIONIn recent years, piled raft foundations have been used in many countries as building foundations. The effectiveness of piled rafts in reducing average and differential settlements has been confirmed not only on favorable ground conditions as shown by Katzenbach et al. (2000), Poulos (2001) and Mandolini et al. (2005), but also on unfavorable ground conditions such as soft clay and/or liquefiable sand using ground improvement technique (Yamashita et al., 2011a; Yamashita et al., 2011b; Yamashita et al. 2013). Grid type ground improvement using the Deep Mixing Method has been applied to sandy ground as a countermeasure of liquefaction to increase liquefaction resistance of unstabilized soil left in the grid walls where its shear deformation during seismic motion is reduced by the confinement effect of the grid walls (Kitazume, 2013). The high applicability of the method was demonstrated in the 1995 Hyogoken-Nambu earthquake and the 2011 off the Pacific coast of Tohoku Earthquake (Tokimatsu et al., 1996; Uchida et al., 2012a; Uchida et al., 2012b).This paper offers a case history of piled raft foundation in soft ground supporting a twelve-story building in Tokyo. To increase bearing capacity of the soft soil as well as a countermeasure of liquefaction, grid-form deep cement mixing walls (DMWs) were employed with the piled raft. First, the results of long-term field monitoring on the settlement and the load sharing among the piles, the DMWs and the unstabilized soil are briefly described. Next, to clarify the contribution of the DMWs to bearing the structure load, the foundation behavior is simulated using a three-dimensional finite element model, and then the results of the numerical simulation are discussed."

Jan 1, 2015

By Renato P. Cunha

The paper presents the results of a comparative and parametric analysis in which a numerical program developed exclusively for groups of deep foundations under general loading (vertical, horizontal and moment loads) was used. This program, developed in the doctoral thesis work of Zhang (2000), extends the finite layer method to accommodate a simultaneous general loading on top of piled raft foundations, allowing the establishment of a coupled relationship between displacements (in all three directions), rotations (in two directions), and external loads. Zhang (2000) has extensively tested and validated this program against well known case histories, but has not applied it to piled rafts overlying unsaturated tropical soil materials. Hence, this paper further explores the applicability of this program by using it to simulate the behavior of experimental field loading tests carried out at the University of Brasilia (UnB) experimental site. At this site, Cunha and Sales (1998) and Sales (2000) carried out several loading tests on small scale isolated rafts (1 x 1m) and piles (L=5m, dia=0.15m), group of piles (4 piles, raft clear off the ground) and piled rafts (1 and 4 piles underneath a raft in contact with the soil). The authors adopt Zhang's program to backcalculate, hence simulate, this series of experimental field loading tests under vertical loading. They also use this set of results to "calibrate" the program for further parametric analyses. The parametric analyses were carried out with different piled raft configurations in this same soil type, trying to evaluate their field behavior under the effect of distinct (geometric) configurations of pile distribution.

Jan 1, 2002

By Muhannad T. Suleiman

The design of deep foundations supporting heavy buildings, bridges, transmission lines, and highway structures, is governed by lateral loads in many cases. However, due to the use of empirical or semiempirical approaches to develop the soil force-displacement relationships (i.e., p-y curves), a wide range of recommendations are presented in the literature. Recent efforts by the author and co-workers enabled simultaneous direct measurements of soil-pile interaction pressure and lateral movement along the pile length, resulting in p-y curves based on direct measurement. Advanced sensors including sheet pressure sensors and shape acceleration arrays were used in these experiments. The experiments were conducted at the Soil-Structure Interaction (SSI) facility funded by the Major Research Instrumentation Program at the National Science Foundation. This paper focuses on the SSI of single laterally loaded piles. The test pile was 101.6 mm in diameter and 1.42 m long, which were installed in well-graded loose sand. This paper provides a summary of the installation and testing procedures, soil properties, pile instrumentation, measured lateral load-displacement response, strain profile along the pile length, lateral movement along the pile length and the pressures measured at the soil-pile interface. Furthermore, the paper presents measured p-y curves compared to estimated p-y curves using empirical methods available in the literature.

Jan 1, 2011

By Alan Alhadeff

Why is mediation being hailed as the wave of the future? The high cost of putting on a trial, over-crowded court calendars and long trial delays have resulted in what prominent attorneys and leading jurists are calling a litigation crisis. In no segment of the legal world are these pressures greater felt than in the trial of the serious construction case. Furthermore, the siege mentality of both the plaintiff and defense bar often leads to a reluctance by either side to make the first reasonable offer for fear of showing weakness. Attorneys operating in the serious construction case arena express concerns that there exist insufficient opportunities for the parties to meet, tell their stories, and negotiate settlement prior to the eve of trial. Mediation, by opening lines of effective communication and encouraging meaningful settlement negotiation, has proven to be a very effective antidote to the litigation crisis.

Jan 1, 1990