Search Documents

By Axel J. Pollak

Since the late 1960's the Interstate Division for Baltimore City (IDBC) has been planning and developing the Interstate Highway System for the city to meet regional planning goals. The principal goals are to provide convenient access to the central business district and the port while diverting through traffic away from these congested areas. Interstate Route 95, an eight-lane highway carrying north-south traffic, has headed the city's priority list; during the 1970's its construction proceeded steadily from both east and west towards the harbor. Closing the final 8800-ft (2670-m) gap under the harbor will complete Interstate 95's construction. This final portion, known as the Ft. McHenry Tunnel project, will be built in nine construction contracts. Construction costs of the complete project are expected to exceed $700 million, making it the costliest single project in the Interstate Highway System. Full funding is being provided initially by the Federal Highway Administration (FHWA), and the Maryland Department of Transportation will re-pay the 10 percent local share from toll receipts within the first three years of operation.

Jan 1, 1989

By Suresh Chikati, Gangadharan Santhanam

Twin tunnels were constructed to a length of 863m using TBM in one of the underground metro projects. The tunnels pass through complex geological conditions (soil, rock and mixed conditions). This paper presents the consideration of volume loss and the corresponding ground settlement associated with the excavation of twin TBM tunnels by analytical and numerical methods. Empirical methods were used to calculate the ground settlement induced by the excavation of twin tunnels. The ground settlement values were directly derived from the two parameters: the volume loss and trough width parameter. These parameters are calculated based on the geological conditions at the tunnel face and tunnel overburden. The finite element software, Plaxis 2D was used to model the soil parameters with appropriate geological conditions. Twin tunnel excavation is simulated in Plaxis 2D and the effect of tunnelling on the ground was simulated by percentage volume loss. The suitable line contraction value was applied to the tunnel linings to simulate the volume loss. The surface ground settlement was directly obtained from Plaxis 2D. Instrumentation arrays were proposed along the twin tunnel alignment, to provide the ground settlement monitoring data within the influence zone of tunnelling activities. The derived ground settlement values from analytical and numerical methods were compared with the actual field instrumentation and monitoring data. From the field instrumentation data, the actual volume loss values were calculated. The compatibility of ground settlement and volume loss calculated using analytical and numerical methods and those measured using field instrumentation data is discussed in this paper.

Sep 1, 2022

By Vijay Kumar, Serhat Baycan, Karsten Beckhans

For the deep foundation of podium and tower of the Kuala Lumpur City Centre, BAUER (MALAYSIA) SDN. BHD. constructed 225 bored piles with diameter range of 2.0 to 2.5 m. In order to comply with the depth requirement of the design, for planning purposes and preparation for site, the drilling equipment was required to achieve a maximum drilling depth of 150 m. Actual piles constructed on site were deeper than 120 m. These dimensions caused superlative challenges which included but were not limited to; controlling the open hole stability over time with polymer, installing 70-ton heavy steel cages, pouring up to 550 m³ concrete continuously, in conjunction with installation of kingposts into workable, fresh concrete. The piling works were executed with a BG 72, the biggest drilling rig globally available, and the stringent verticality of the pile bore holes which required approval prior to cage installation. For verification of verticality, Bauer’s patented Drilling Inclination System was successfully used.

Nov 1, 2022

By Michael Forrest, John Roadifer, Glen Gorski

"The Calaveras Dam Replacement Project (CDRP) requires large disposal sites to store excess excavated materials that could not be utilized for dam construction. Because of access restrictions during design, the disposal site rockfill toe dike area at the edge of the reservoir could not be explored to evaluate soil conditions. As such, the site had to be explored as part of the construction contract. Exploration revealed very soft clay and loose silty sand up to 40 feet thick that would not be able to support the rockfill dike at the toe of a large disposal site fill. Several alternatives were evaluated to stabilize these soils. Based on constructability, cost and risk considerations, cement deep soil mixing (CDSM) was selected as the preferred method of soil stabilization. The challenge was to design and construct the CDSM stabilization to minimize construction delays. A joint effort by the design engineer, construction manager and contractor achieved CDSM stabilization in about three months, from design through completion of construction. A rigorous quality control program included compression testing of both wet grab and cored soil cement samples to demonstrate that specified strength requirements were being achieved.INTRODUCTIONDisposal Site 3 (Figure 1) is one of the primary CDRP disposal sites having a height of 240 feet and a storage capacity of about 2,500,000 cubic yards. An approximately 40-foot-high rockfill dike at the base of the disposal site provides an erosion resistant toe for the disposal site. The rectangular foundation area shown in red was not able to be investigated during design because of access restrictions."

Jan 1, 2015

By Thomas L. Vande Voort

The strategic plan for bridge engineering issued by AASHTO in 2005 identified extending the service life and optimizing structural systems of bridges in the United States as two grand challenges in bridge engineering, with the objective of producing safer bridges that have a minimum service life of 75 years and reduced maintenance cost. Material deterioration was identified as one of the primary challenges to achieving the objective of extended life. In substructural applications (e.g., deep foundations), construction materials such as timber, steel, and concrete are subjected to deterioration due to environmental impacts. Using innovative and new materials for foundation applications makes the AASHTO objective of 75 years service life achievable. Ultra High Performance Concrete (UHPC) with compressive strength of 26,000 psi (180 MPa) and excellent durability has been used in superstructural applications but not in geotechnical and substructural applications. This paper explores the possibility of using precast, prestressed UHPC piles in future bridges. An H-shaped UHPC section, which is 10-in. (250-mm) deep with weight similar to that of an HP10×57 steel pile, was designed for constructability and economical reasons. Instrumented UHPC elements were cast to conduct large-scale field tests. In the field, two UHPC piles have been successfully driven in glacial till clay soil and load tested vertically. Test results, durability, drivability, and other material advantages over normal concrete and steel indicate that UHPC piles are a viable alternative to extend the life of bridge structures.

Jan 1, 2008

By Daniel A. Thome, Robert C. Janke

"Installation of permanent soil nails through distressed mechanically stabilized earth retaining walls is a cost effective and aesthetically pleasing solution when using the appropriate equipment and drilling methods for installation. A forensic investigation was performed on an existing mechanically stabilized earth retaining wall to determine the possible causes for the excessive horizontal displacements and visual structural flaws found along a portion of the wall. Reports concluded that the visual shifting was due to a number of factors including improper drainage in the vicinity of the wall and unsuitable compaction of the backfill material. Conceptual designs were proposed to the owner and the installation of permanent soil nails through the existing precast panels was determined to be the most practical solution. A total of ninety-three permanent soil nails were installed to lengths of up to 40 feet (12 m) through sand backfill and silty day fill using a hydraulic rotary percussion drill attached to a tract mounted excavator.IntroductionThe Illinois State Toll Highway Authority awarded Contract RR-03-5144 in the summer of 2004. Construction work for the project consisted of the rehabilitation of two existing concrete culverts and approximately 100 linear feet (31 m) of mechanically stabilized earth (MSE) retaining wall. The retaining wall is located below the southbound lanes of the Tri-State Tollway near the intersection of Federal Highway 41 in Wadsworth, Illinois as shown in Figure 1.Reports were prepared by Applied Technologies in cooperation with Giles Engineering Associates to determine the condition of the MSE wall and recommended conceptual designs to extend the service life of the wall.Nicholson Construction Company (Nicholson) wasselected as the design-build geotechnical subcontractor to install the recommended permanent soil nails through the existing precast concrete panels of the MSE wall. Rehabilitation of the wall involved the installation of ninety-three permanent soil nails through the existing wall, along with soil nail verification tests and proof tests on production nails."

Jan 1, 2005

By Amanda R. Parry, Chris R. Pray

Predicting and modeling the soil structure interaction of laterally loaded piles with significant unbraced lengths is one of the challenges faced in designing many waterfront structures. Designers often rely on pile specific design software to calculate forces in an embedded pile and then couple that with either a structural design software to capture the behavior of the rest of the structure or use potentially overly conservative assumptions to omit modelling the piles entirely. Given that some projects have hundreds of piles coupled with hundreds of loading conditions, the shuttling of results from the structural analysis software into the pile analysis software can become cumbersome, difficult to track and manage, and prone to user input errors. An alternative approach recently used on two large marine infrastructure projects consisted of calibrating a structural analysis software to replicate the resultant outputs from a software developed specifically for pile analysis. This calibration was done using thoughtfully placed springs along a pile modeled in the structural analysis software to replicate the soil-structure interaction of the piles. The focus of this paper will be on the methodology used to calibrate the two software programs and an evaluation of the results which showed close agreement. Based on the two case studies, calibrating a generic finite element analysis software via this method should be considered as a reasonable and time saving design approach for pile-supported structures.

Sep 8, 2021

By Renato P. Cunha

The paper explores a parametric analysis of a four-pile group in contact (hence piled raft) and without contact (hence standard pile group) with the superficial soil layer, under a combined set of loadings (moment M, vertical V and horizontal H forces). The major design parameters of interest, as total and differential settlements, and raft bending moments and shear stresses are assessed under aforementioned distinct conditions. The slenderness ratio of the piles is also varied along the analyses, allowing the establishment of its influence on the derived parameters.

Jan 1, 2006

By Andrew Middleton, Mick Stadter, Chris Crowe, David Chong

"The Level Crossing Removal Project – Package 1 is part of the Victorian Governments commitment to remove 50 of the most dangerous and congested level crossings across Melbourne. This involved removing three crossings on the Frankston Line in the south east suburbs of Melbourne. The works involved replacing approximately 2.5km of at grade track with three rail cuttings up to 8 m deep at each of the bridges that replace the level crossings. The cuttings are retained by piled retaining walls and during the main construction occupation approximately 250,000 cubic metres of soil was removed. The project has presented significant geotechnical challenges due to the location in residential suburbs and tight rail corridor and rail occupation timeframe. These challenges included temporary and permanent wall stability, foundations, earthworks and dewatering. As a result, careful design and innovative construction techniques have been necessary to limit impacts on the community and meet the project timeline.INTRODUCTIONThe Level Crossing Removal Project – Package 1 is part of the Victorian Governments commitment to remove 50 of the most dangerous and congested level crossings across Melbourne. This involved removing three crossings on the Frankston Line where it crosses North Road in Ormond, McKinnon Road in McKinnon and Centre Road in Bentleigh.The project involved replacing approximately 2.5km of at grade track with three rail cuttings up to 8 m deep at each of the bridges that replace the level crossings. The cuttings will accommodate three lines of rail tracks with the cuttings up to 25 m wide. The cuttings are retained by piled retaining walls and during the main construction occupation approximately 250,000 cubic metres of soil has been removed.The project presented significant challenges due to the location in residential suburbs and tight rail corridor and rail occupation timeframe. As a result, careful design and innovative construction techniques have been necessary to limit impacts on the community. The geotechnical challenges generally fell into one of three areas, earthworks, structures and groundwater. The primary earthworks challenge for the project was moving the 250,000 cubic metres of soil in a 10 day window, however, from a geotechnical viewpoint, obtaining a stable subgrade on which to operate the necessary construction plant in a short time frame with constrained site access and time to import materials was the key. Whilst closely watching the performance of the dewatering system, a range of contingency plans were developed to cope with any difficulties."

Jan 1, 1900

By C. Vipulanandan

Installation procedure and the quality of the material used in the construction have significant effects on the behavior of the Auger Cast in Place (ACIP) piles. In this study, Installation and curing of a 760 mm (30 in.) diameter and 12 m (39 ft) long ACIP pile with a design capacity of 1140 kN (128 tons) in hard clay was investigated. Construction quality was monitored using the automated monitoring system where the volume of grout pumped and the pressures were monitored with depth. The curing of the pile was monitored using axial vibrating wire strain gages at four levels and lateral vibrating wire strain gages at two levels. The residual strain and temperature profile in the curing pile was monitored over a period of week to determine the appropriate time for load testing the pile. Axial behavior of Auger Cast in Place (ACIP) Piles in hard clay was studied using full scale load test on an instrumented pile. The load-settlement and load transfer relationships of the pile was investigated based on the load test results. Development of skin friction in the load test pile and the reaction pile was also investigated.

By Robert S. Thomas, Bernard M. Tarralle, Nasser Massoudi

"The Commonwealth of Virginia is restoring and expanding its Capitol of great historic significance. Designed by Thomas Jefferson in 1785, it is the second oldest Capitol building in the United States. The building expansion required excavations immediately adjacent to its South Portico. The building, which rests on shallow brick footings, is very sensitive to any disturbance caused by construction and excavation. A comprehensive and secure plan of operations was devised by the design team to ensure that this national monument remains unharmed by the new construction. Various construction techniques were implemented to satisfy the strict movement goal of 0.25 inch and distortion of U2000. They consisted of jet grout columns to stabilize the upper soils, compensation grouting for future foundation leveling, a tied-back reinforced concrete diaphragm wall for excavation retention and foundations, and realtime instrumentation for monitoring. This paper describes the design approach for the retention system, providing information on the various construction phases and techn iques, and reports on the movements recorded by the real-time monitoring system during the course of the project. At the time of this manuscript preparation, and the deep excavation complete to final grade, the results indicate that the extremely restrictive building movement criteria have been met. The success can be credited to detailed design, close cooperation among the project team, prudent construction methods, and real-time monitoring. INTRODUCTIONThe Commonwealth of Virginia is undertaking a comprehensive renovation and expansion of the Virginia Capitol building located in Richmond, Virginia. The Capitol building was designed by Thomas Jefferson in 1785, with construction of the original building starting the same year. The Capitol building was designated a National Historic Landmark in 1960 and was listed on the National Register of Historic Places in 1966.A part of the comprehensive renovation and expansion of the Capitol is a 25,000-square foot, two-level subterranean extension on the south side of the Capitol building, which will serve as a new Visitor Center and public entrance for the Capitol. Deep excavations were required for the construction of the new Visitor Center. The excavation required a permanent retention system to accommodate an approximately 40- foot deep excavation."

Jan 1, 2005

By Paul M. C. B. M. Cools, Martin Th. van Staveren

In 2010, the 5-years joint industry programme Geo-Impuls started in the Netherlands. The ambitious goal of this programme is to reduce geotechnical failures in our civil engineering projects by half in 2015. In the Geo-Impuls programme over 40 client organizations, engineering firms, contractors, research institutes, and universities are involved. In a risk-driven way, and based on top risks and dilemmas, the participants defined three central development themes. These themes are (1) contracts, for dealing with legal issues, (2) geo-engineering, for dealing with technical issues, and (3) communication, for paying attention to differences in risk perception by the human factor. In total 12 Working Groups contribute to these themes by producing one or more specific tools. These provide practical solutions for how to deal with contractual, geotechnical, and communication issues. The tools include working processes, guidelines, best practices, as well as some instruments. The development of these tools, as well as the available results, will be presented in this paper. From the start, Geo-Impuls embraced geotechnical risk management (GeoRM) as the risk-driven way of working for geotechnical engineering and construction. Over the past years, GeoRM and its supporting tools were already successfully applied in several projects. Therefore, the paper also describes also the GeoRM implementation process, including the quality assurance and control. Finally, the effectiveness of GeoRM will be discussed, by summarizing an analysis of all published geotechnical failures and accidents in construction projects in the Netherlands, which decreased substantially over the past 4 years.

Jan 1, 2017

By Robert Alperstein, Nidal AbiSaab, Joe Pastore

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

Jan 1, 2016

By George Filz, Peter R. Cali

"Unnecessarily restrictive specifications could be limiting the cost effectiveness of deep mixing (DM) applications and therefore limiting use of DM on projects where there are other options. Excessively restrictive standards demanded for strength and permeability certainly increase contractors’ bid prices, and costing the owners and, in the case of Government projects, the taxpayers more than necessary. Yet, lax or ineffective specifications often exist for some vital components of the quality assurance and quality control. In this paper, specifications for key elements of DM design and construction are examined. Recommendations are made to improve and streamline DM specifications to better serve the common objective of constructing a safe and cost effective ground improvement project.INTRODUCTIONSpecifications should, at their best, convey the project design requirements and provide clear direction to the contractor regarding requirements for submittals, materials, execution, measurement, schedule, and other aspects as necessary. The specifications should not be overly conservative, restrictive or ambiguous, and they absolutely should not be deficient in measurement of quality. Guide specifications or recycled sections from previous projects often form the template for new project specifications. But standards that appear in guide specifications or from former successful construction should be critically scrutinized by the designer for relevance before using the copy/paste functions of the specifications writer’s keyboard. Because work does not always go as smoothly as planned, specifications for remediation of non-compliant construction should be clearly stated and enforced. Often, non-compliancy is reviewed after-the-fact and deemed to have met the design intent, indicating that either the specifications were too restrictive or the enforcement too weak.The Federal Highway Administration Design Manual: Deep Mixing for Embankment and Foundation Support, October 2013, was written by a panel of DM expert design practitioners and contractors. Guide specifications are included as Appendix C of the FHWA manual. Those guide specifications have been updated in the deep mixing section of the www.GeoTechTools.org website, and the updated specifications represent the most complete and authoritative compilation published to date. Although the specifications for DM at www.GeoTechTools.org are current and complete, and they portray the state-ofthe- practice, they too must be modified to fit specific DM applications, project needs, and site conditions. The keys to a good set of specifications are to prescribe construction only to the level that is required to meet the design intent, to require appropriate quality control and quality assurance (QC/ QA) activities, and to clearly address remedial measures required for non-compliant work."

Jan 1, 2015

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

By Stefan Larsson, Sadek Baker, Razvan Ignat

"This paper describes the execution of two full-scale field tests where a braced steel sheet pile wall interacting with rows of overlapping dry deep mixing columns was first excavated and then loaded to failure. The aim of the tests is to provide insight of the performance of dry deep mixing column rows located in passive zone and interacting with a retaining structure. The column rows were installed perpendicular to the sheet pile walls with two different area ratios, i.e. different distanced between the column rows. Both tests were extensively instrumented with inclinometers, pore pressure transducers, bellow-hoses, earth pressure gauges and strain gauges mounted on the struts. Results of the performedtests will serve as development of design methods for excavation support with columns.INTRODUCTIONDry deep mixing has been used with good results to strengthen the soil when excavations are to be performed in locations with thick soft clay deposits. An application that has increased in recent years is to install columns on the passive side of the retaining structure. Columns can be installed in different patterns but rows, grids or blocks are the most common arrangement. The use of column type ground improvement installed on the passive side of a retaining structure has been documented for a few field cases, Tanaka (1993), O’Rourke et al. (1997b), O’Rourke and McGinn (2006), Ou et al. (2008). By improving the soil on the passive zone, the passive earth pressure in front of the retaining structure is increased. This has proven to reduce the excavation induced deflections behind the retaining structure, reduce the structural forces (bending moment in the retaining structure, strut and anchor forces) and improve the safety against basal heave failure. The main focus of the conducted measurements within these cases has been on recording deflections and structural forces on the retaining structure and there is very little documentation available of the stress-strain behavior of the improved soil acting on the passive side of the retaining structure.Two full-scale tests of braced steel sheet pile walls interacting with rows of overlapping dry deep mixing columns were first excavated and then loaded to failure was conducted during the spring-summer of 2014. This paper briefly describes the test set up, instrumentation, test procedure and some selected results from one of the conducted tests."

Jan 1, 2015

By Song-yu Liu, Chao Yan, Yong-feng Deng

"In order to investigate the stability of embankment on soft subgrade improved by T-shaped deep mixed column composite foundation, the internal forces and failure modes of columns were analyzed on the shape of critical slip surface and the displacement fields of composite foundation through strength reduction method of three dimensional numerical simulation. Then comparison between T-shaped and conventional deep mixed column composite foundation were conducted. The simulation results indicate that the stability analysis was overestimated by limit equilibrium methods. Piles within the slope shoulder provide great resistance slide effect through the vertical bearing capacity, while the piles nearby slope shoulder and outside slope shoulder providing great moment to resistant slip. The embankment stability of T-shaped deep mixed column composite foundation is higher than that of conventional deep mixed column composite foundation while cost less cement and construction time.INTRODUCTIONThe soft soil has many unfavorable project properties such as high compressibility, low strength, and high water component. Embankment built on the soft soil will face subsidence, horizontal displacement and stability problems. Cement-soil deep mixed column composite foundation is more commonly used as a method for construction of embankment on soft ground [1-2]. For the existing problems of China's current cement-soil pile (wet jet mixing pile), including strength uneven, effective treatment with shallow depth and high cost, a new technique, T-shaped bidirectional deep mixed column, is introduced [3]. An automatic expanding mixing blade was developed by Liu et al. shown in Figure. 1, to install TDM columns [4].T-shaped deep mixed (TDM) column combines bi-directional deep mixing technique and T-shaped deep mixing technique: ?Using concentric biaxial drill pipe, opposite rotational direction of the blade on the inner drill pipe and the outer drill pipe. By squeezing action of the blade on the outer drill pipe, forward and reverse rotation of the blades bidirectional mixing at the same time, blocking the way to take the grout, the uniformity of cement mixing is improved. ?Scalable stirring blades, which can be stretched for two different radius at any depth below ground, expand cross-section of the upper pile (enlarged head), forming expanding cross-section within the upper part of a certain depth which is similar to the shape of nail. As a new composite foundation, T-shaped mixing pile composite foundation is widely applied. However, studies on the stability of T-shaped column treated soft subgrade are rare in the research. So the stability study on T-shaped column composite foundation under embankment for guiding the design and construction has important significance."

Jan 1, 2015

By K. Madhusudan Reddy

Pile response under combined uplift and lateral load is very important and it is imperative to evaluate the effect of combined loading and only few studies were reported on pile behavior under combined uplift and lateral loads. Model pile made-up of aluminum having an outer and inner diameter of 25.4 mm and 19.4 mm respectively is used. Dimensions of the model steel tank are fixed as 1.0 m x1.0 m x 1.2 m (depth) to avoid the boundary effects under combined lateral and uplift loads. Experiments were carried out on single piles at isolated uplift, isolated lateral loading and combined lateral and uplift loading, embedded in sandy soil. Results indicate that load?deflection behavior is nonlinear for isolated uplift and lateral load tests as well as in case of combined loadings. It is also observed that the behavior of piles under isolated loadings is substantially different when compared to combined loading.

By Musbah A. Hasan, Ahmed M. Nasr, Fauzi Jarushi

Many transmission towers, high-rise buildings and bridges are supported by piles. These structures may be subjected to large lateral loads. Therefore, experimental investigations on model piles under lateral loads were conducted in uniform dry sand. Small-scale model tests were carried out considering the influence of pile length, pile diameter, sand density, roughness of pile surface and vertical load on the lateral resistance of a pile. Furthermore, the effect of pile load eccentricity (e/L) on the ultimate lateral resistance was studied. Investigations, of the influence of various parameters on the magnitude of the coefficient of subgrade reaction (nh), were also performed. It was found that the lateral load capacity of piles increases with increase in pile length, pile diameter, pile surface roughness and increase in the sand density. The results also showed that the coefficient of horizontal modulus of subgrade reaction, (nh), decreases with deflection increase. From the results, the coefficient of subgrade reaction for a smooth pile embedded in medium dense sand would decrease by (134%) when the lateral pile head deflection (yg) changes from (2% to 5%) of pile diameter.

Jan 1, 2017

By David Corke

The paper presents the development of Federation of Piling Specialists (FPS) calculation of rig track loading, the production of the Building Research Establishment document “Working platforms for tracked plant” (BR 470), working platform testing and considerations of rig stability. The paper also discusses the importance of rigorous and well documented procedures and proposed future development of rapid working platform testing methods. Topics presented include the fundamental requirements and principles involved in the testing, design and maintenance of working platforms, rig track loading, the BRE design method and site testing analysis. The paper stresses the need for testing and design processes to be robust and simple and quick to perform as there is often little time between the award of a contract and the need to start work on site. Also, it is vital that all aspects of working platform design can be carried out with information that is available to the platform designer. Developments in the UK over the last two decades have resulted in improved quality and safety of working platforms that will hopefully be further enhanced as design and testing methods continue to improve.

May 1, 2022