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By Tomio Tsuchiya

A construction method of bored steel H piles enclosed in soil-cement columns was developed by modifying steel H piles from the driven pile method and soil-cement walls from the earth retaining wall method, the latter of which produces cut-off walls and reduces noise and vibration during construction. In this method, as shown in Figure 1, rich mix cement paste is injected into the bottom of a borehole which is pre-excavated by a casing auger, then a steel H beam is inserted before it hardens. Since the high vertical resistance of piles created with this method has already been confirmed by loading tests, we have been investigating the applicability of this method for piles used to temporarily support building loads for top-down construction on raft foundations until the raft foundation is completed. However, in the loading tests, the bearing capacity at the lower end of the pile was measured by loading from ground surface on test piles which had friction cut to eliminate the shaft friction resistance. In other words, the loading tests neglected the effect of overburden pressure of soil above the lower end of the pile. To investigate the effect of the overburden pressure on the bearing capacity at the lower end of the pile, loading tests were carried out on a bored steel H pile of lm diameter (test pile) bored in a compacted sandy soil layer with N-value of 100 to 250 at each stage of a three-step excavation. The results show no significant change in the bearing capacity at the lower end of the pile when the depth ratio of the pile is in the range of 5.7 to 22.7.

Jan 1, 1996

By J. P. Burland

The paper describes a number of recent case histories in the United Kingdom where field instrumentation and measurements have played a major role in the design and construction of excavations, piles and foundations. It is shown that the design and construction procedures for deep excavations in London Clay are based almost entirely on the results of field measurements. Examples are given of successful application of such measurements. The present understanding of the behaviour of bored piles in stiff clays and their design is based on a number of instrumented pile loading tests. The results of these tests have led to a radically new concept of pile design in which the piles operate at their full shaft capacity under working loads thereby resulting in considerable savings in design and construction. Some examples of the successful application of this concept are given. Finally it is shown that the present knowledge of the stiffness properties of chalk is based entirely on field observations. An example is given of how direct field measurements were used to solve a foundation problem at the base of a coffer-dam in chalk.

Jan 1, 2010

By Michael Perlow

Helical screw piles in use since 1838 are routinely used for energy, transportation, municipal, industrial, marine and coastal infrastructure as well as for excavation support, environmental remediation, and foundation repair. They are especially well suited for work in constrained areas, renovations and structure retrofits. Helical pile design procedures over the past 10 years have gone through a remarkable evolution with the establishment of the 2007 AC358 Helical Pile Acceptance Criteria and inclusion of helical screw piles in the 2009 International Building Code (IBC). New 2009 IBC building code requirements and AC358 Acceptance Criteria are presented along with advances in helical pile design procedures, installation, QA/QC, and recommended load test verification criteria. Use of helical smart piles to validate helical pile design and verification of ultimate pile capacity is highlighted.

Jan 1, 2011

By Schmitz Stefan, Stephan Jee-Sun

"Due to the reunion of Western and Eastern Germany in the late 80’s, a multitude of infrastructure projects had to be executed. A good portion of these projects required improvement of the motorway system. In the southern region of Leipzig, in the eastern part of Germany, it was required to connect two existing motorways. Parts of the new motorway pass old strip mining areas. These strip mining areas consist of up to 70m thick backfill material. Especially the upper 20m are very inhomogeneous soil material with a very low bearing capacity. In order to increase the bearing capacity, to decrease the differential settlements and to homogenize the soil parameters, soil improvement using sand-gravel columns was required. Bauer Spezialtiefbau GmbH executed the installation of approx. 711,000 linear meters of columns with a length from 5 m to 25 m. For the project, 11 rigs with frame leads up to 40m were used to install the 43,000 columns with a diameter of 0.8m in 27 weeks.1. INTRODUCTION1.1 Site LocationThe construction site is located in the south-eastern part of Germany, in the south west of the city Leipzig.The area to be treated had a size of approx. 500,000 m² to allow the construction of dam/embankments and a highway bridge.1.2 Required WorkIn addition to the general earthworks and the installation of geogrids and fibre mats, a total amount of more than 710,000 linm of Gravel-Sand Columns with different lengths due to the given soil conditions had to be installed:•nos. 4,206 Columns length 5m ? 21,030 linm•nos. 4,581 Columns length 10m ? 45,810 linm•nos. 10,820 Columns length 15m ? 162,300 linm•nos. 19,634 Columns length 20m ? 392,680 linm•nos. 3,574 Columns length 25m ? 89,350 linmFor the installation of the columns Gravel-Sand with the grain size of 0/32mm was used. The total amount of Material was 580,000mt"

Jan 1, 2015

By Anupam Saxena

This paper presents a case history of design, prediction, probe and production pile driving monitoring, loading test, and installation of piles for a 22-story condominium tower in southwest Florida, U.S.A. ASC was commissioned to provide value engineering services in the proper selection of an economical and satisfactory foundation system. For the site-specific subsoil conditions, various types of foundations were considered and following an evaluation of high structural loads, site-specific constraints, and the production timeframe mandated by the project owner, a prestressed concrete pile-supported system was selected as an economical and effective foundation approach. The building foundations were designed for a compression capacity of 575 kN (65 tons) for the tower and 220 kN (25 tons) for the parking structure. The axial pile capacity and lengths were predicted using SPT91 software. The validation of these capacities was derived from driving 21 probe piles and performing static loading tests on selected probe piles (2 in compression and 1 in tension). The predicted pile capacities were evaluated with results from static loading tests on selected probe piles. This information was effectively utilized as part of an overall quality control program to install a total of over 920 prestressed concrete piles to lengths ranging from 11.5 to 16.5 m (37 to 54 ft) below existing ground elevation as part of the foundation support system.

Jan 1, 1996

By Julie Clarke

In 1939 Dr. Ralph Peck criticized the Civil Engineering community for taking a bifurcated approach to the prediction of building damage due to subsurface geo-technical works. Specifically, he observed that Geotechnical Engineers concerned themselves only with subsurface issues implying that their results were largely independent of the presence and condition of the structures above. He continued that Structural Engineers charged with risk assessment of buildings approached their work nearly in isolation of below ground activities. Seventy years later, although the state-of-the-art has enabled a better understanding of soil-structure interaction, the reality remains that risk assessment from subsurface construction, is not yet an integrated activity when done on a large-scale basis. To help move beyond this, this paper proposes a new, integrated methodology for preliminary assessment that considers a three-stage process that involves the following: (1) traditional empirical relationships for predicting ground movement from tunneling, (2) recent advances in condition assessments, and (3) architectural designators related to usage and historic preservation listings. The methodology is applied to a study area of nearly 260 buildings in the city center of Dublin Ireland, in an area slated for an upcoming metro. The results are com-pared to the Environmental Impact Statement issued for the official project. Al-though the test case is for tunneling, the approach may be adapted to other subsurface construction activities including excavation and piling.

Jan 1, 2009

By Filippo Leoni, Wesley Schmutzler

"The LPV-111 East Back Levee Improvement Project lies along the Gulf Intracoastal Waterway (GIWW) in Orleans Parish of New Orleans, La., and is an essential component of the New Orleans Hurricane Protection System. The Hurricane Protection Office of the U.S. Army Corps of Engineers (USACE) attributed failure of the New Orleans East levees system to overtopping, erosion and subsequent breaching of LPV-111 along the GIWW, as well as other sections of flood protection during Hurricane Katrina in 2005. The existing levee suffered extensive damages from Hurricane Katrina, such that the USACE elected to provide earth stabilization and to rebuild the levee sections. Due to the adverse geotechnical properties of the foundation soils, the Corps deemed ground improvement necessary to stabilize the new levee and to limit its footprint. Wet Deep Mixing Method (DMM) was selected as the most suitable technology for this task.ChallengesDesign: This reach specifically protects East New Orleans and the Bayou Savage National Wildlife Refuge, the largest urban wildlife refuge in the U.S. and home to several threatened or endangered species of birds as well as many reptiles, amphibians and small mammals. The Corps chose DMM due to the sensitivity of the protected marshlands and because the method limits the footprint of the raised levees. The increase in the load bearing capacity of the treated soil significantly decreases the footprint necessary to attain the required height increase. This limitation required the new levee to have steep slopes, drastically increasing the surcharge on foundation soils characterized by overall poor geotechnical properties (soft clays and peats). The design also considered the increased horizontal stresses on the levees due to the extreme storm surges during a hurricane.The design of the 1.6 m diameter (5.25 ft) DMM elements called for overlapping them to form a double auger element that formed buttresses perpendicular to the levee alignment. The contractor installed the buttresses at a maximum on center spacing of 4.7 m (15.5 ft). One additional double auger DMM element was midway between consecutive buttresses at the centerline of the levee to further help prevent settlement (Figure 1)."

Jan 1, 2013

By Hitoshi Ogura, Koichi Kobayashi, Sadao Yabuuchi

"In Japan, most pile foundations using pre-cast concrete piles are installed by the bored pre-cast piling method, wherein pre-cast piles are installed in holes that have been excavated beforehand and filled with cement milk (term used for cement water slurry in Japan). The bored pre-cast piling method with enlarged base, in which the portion near the toe is enlarged during boring operation, is widely used because of the cost benefits and the increased vertical bearing capacity that this method offers.The EX MEGATOP method, further developed as an improved bored pre-cast piling method with enlarged base, is reported here. The features of this method are: (1) High vertical bearing capacity; (2) High degree of freedom in design; (3) Excellent workability; and (4) Friendly to the environment. In particular, high vertical bearing capacity can be obtained using nodular piles and by enlarging the area at the pile toe and shaft. This method can gave a vertical bearing capacity coefficient at the toe of a=430, more than twice the corresponding value of a = 200 of a conventional bored pre-cast pile. Moreover, the shaft resistance can be several times larger than that of a conventional bored pre-cast pile. This report gives an overview of the EX MEGATOP method, evaluation of vertical bearing capacity, and examples of application of the method.1.lntroductionMost pile foundations in Japan are installed by the bored pre-cast piling method, that is, in holes that have been excavated beforehand and filled with cement water slurry, referred to as 'cement milk'. The ""bored pre-cast piling method with enlarged base"" is frequently used. In this method an enlarged excavation is used near the pile toe to increase the vertical bearing capacity.The EX MEGATOP method is a variation of the bored pre-cast piling method. Its features include the use of nodular piles and a long, enlarged excavation. The vertical bearing capacity of the EX MEGATOP method is described in this report."

Jan 1, 2005

By David Coleman

This paper presents a case history involving the installation of drilled in piles with rock sockets for the Bicycle and Pedestrian Path project located west of the Henry Hudson Parkway within the Riverside Park between 83rd Street and 91st Street at the Hudson River in New York, NY. The paper specifically addresses access and construction procedures for a marine installation when working in an urban and environmentally sensitive setting.

By Maral Papazian Bedian

"Case 2. 100th Street Bus Depot: Elimination of Deep Caissons in Favor of Spread FootingsThe PROJECTThe 100th Street Bus Depot is a new five-story bus terminal for the New York City Metropolitan Transit Authority occupying one city block in Manhattan between 99th and 100th Streets, and between Lexington and Park Avenues. It replaces a former two-story garage, built in the 1890’s and initially used as a trolley-car barn. The new structure is a steelframed building with concrete floors and includes a partial basement near its middle. The easternmost column line with design loads of 10 MN (1,125 tons) is within 1.5 m of the underlying multi-tube Lexington Avenue subway system. To support the new columns along the subway line, the project bid plans had called for 1 m diameter and 17 m deep drilled shafts. The upper 14 m of each unit would have required 50 mm separation from the surrounding rock to prevent stress from being imposed on the roof and walls of the adjacent tunnel. The column loads were thus transferred to below the base of the tunnel and supported by 3 m long sockets in bedrock. The bid documents contained extensive test boring information, which revealed that the project site was underlain by massive Manhattan Mica Schist bedrock within just 3 m below street level. In fact, the Lexington Avenue two-level and multi-tube subway had been tunneled through this rock circa 1910, leaving an about 6 m thick solid roof over the upper-level subway. The NX rock core recovery values were near 100 %, with average RQD of 75 %.The CHANGEThe Bus Depot project was let as a design/build contract with a very aggressive fast-track schedule. Both the pre-bid preliminary design and the subsequent final design by the Contractor’s own hired design engineers relied heavily on very restrictive codes, including unnecessarily conservative approaches to seismic design. Any suggestion for value engineering change was undesirable and was strongly resisted. Yet, objecting against the blind reliance on codes in foundation design, the author questioned the real need for the deep drilled shafts to support the columns along the subway. The unsupported statement that no stresses from the new structure can be imposed on the roof and walls of the adjacent tunnel was not sufficient reason for the drilled-shaft design. Unconvinced that deep shafts were necessary, the author rushed to MTA’s warehouse where many rows of rock core boxes were neatly stacked. Careful inspection and some simple testing of the rock cores with the blows of a geologic hammer gave support to the reservations about the design. Later, as expected, the schist bedrock at this site was found to be hard to very hard with unconfined compressive strength values estimated to range from at least 70 MPa to over 100 MPa (10,000 psi to 15,000 psi). The tensile strength of the rock was assessed to be minimum 5 MPa (750 psi)."

Jan 1, 2003

By Rouzbeh Vakili, Adel M. Hanna

"The application of piled raft foundations has significantly increased during the last few years. In this system, the raft and the pile group collectively transfer the applied building load to the underlying soil layers. Determination of load sharing between the raft and the piles derives the complexity of piled raft designs due to its multi-parameter nature. These parameters are but not limited to: soil density, pile length, pile spacing, raft geometry, and piles installation technique. This study is to examine experimentally the effect of sand density and pile installation techniques on the load sharing mechanism. Experimentally, tests were conducted on a square rigid raft with a single pile in sand under three different soil densities; 30%, 45%, and 60%. The experimental results are used to determine the pile and the raft shares in non-displacement and displacement piled raft systems. The results of this study reveal that soil density changes the load sharing of displacement piled raft; the pile share increases in higher soil density. However, this is not the case in non-displacement piled raft and load sharing is independent of soil density in working loads.IntroductionThe piled raft foundation is a combination of shallow and deep foundation which transfers the superstructure load to the soil by a complex soilstructure interaction. The interacting mechanism among foundation elements and their surrounding soil is illustrated schematically in Figure 1 and could be classified into two categories: (1) pile-soil-pile and (2) pile-soil-raft. The pile-soil-pile interaction is the same as the free standing pile group and is a function of pile spacing and pile installation method. Pile-soil-raft interaction, which only involves in piled raft foundation design, could be affected by: the length, spacing, and roughness of the pile, the rigidity and dimension of the cap, soil condition, and the pile installation method. Pile-soil-raft interaction could have favourable and unfavourable effects on bearing capacity and settlement, respectively. The pressure between the cap and the soil favourably increases the horizontal stress on the pile shaft and consequently increase the shaft resistance. Whereas, this pressure induces negative skin friction on the piles which increases the settlement. The pile-soil-raft interaction mainly controls the load sharing mechanism of piled raft foundation when pile spacing (S) is more than 3.5dp."

Jan 1, 2017

By Bernardo J. Jiménez, Harlem Lora, Roberto Acosta Mora

Circunvalacion Norte project is currently the most important infrastructure project in Costa Rica. It is the last segment of the urban perimeter highway. Site investigation of local geotechnical conditions were studied by SPT, CPT, pressuremeter tests and boreholes. A static load test was executed as a proof test with an associated ultimate resistance of 12056 kN (2710 kips). Drilled shaft design was done using PMT tests and axial nominal resistance varied between 4000 kN (900 kips) and 6000 kN (1350 kips). A total of 416 drilled shafts were constructed in 15 months with drill performance of 32 m/day (105 ft/day). Drilled shaft lengths varied between 4,0 (13 ft) m and 40,0 m (130 ft). Selfconsolidating concrete was used to achieve an adequate workability even in high densities rebar cages. Several site conditions proved the importance for maintenance of the working platform, predrilling of rock sockets and having spare parts to avoid increase in project’s cost. New procedures were taken to prevent concrete segregation on excavations near underground water flow. Monitoring the quality of the shafts from CSL test showed less than 3% of the shafts presented a considerable anomaly, which proved that the adopted construction method and materials were adequate. For the concrete anomalies, successful remediation was performed by means of grout at the base of the shaft with two different types of drilling methodology depending on the concrete anomaly.

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 Vivian M. Troughton, Clifford J. Wren, Tony P. Suckling

"Secant pile walls are used for the construction of deep basement walls and earth retaining structures. Risk associated with secant pile walls is commonly perceived as being the safety of site personnel and the public during piling operations, or safety used in design. It is recognized that both of these are of paramount importance, but additional risks associated with the construction methods must also be considered to complete the risk management profile for any project. For the particular case of secant pile walls, if Clients take a ""back seat"" they may be unaware of the total risk package they are procuring. The authors argue that the piling contractor should be involved at the earliest stage giving input into the overall risk management process. Such early involvement within the professional team will maximise cost benefits to the Client and minimise the delays and cost increases sometimes associated with these works. A consistent methodology for identifying and then managing all the risks associated with secant pile walls is proposed. An example is used to demonstrate how this methodology should be employed. INTRODUCTIONThis paper discusses the value of a complete and integrated risk management process for structures with basements formed using a secant pile wall.The risk associated with any secant pile wall can be consicfered as comprising four components;1. Safety of people on site2. Safety of design or design methodology3. Construction risks4. Commercial risksAny risk management system needs to fully consider and integrate each of these four components to maximise the likelihood of a successful outcome for the basement.This paper concentrates on the construction risks for secant pile walls, as these are not often understood by the Client (in this paper the term ""Client"" also includes the main contractor, principal contractor, Engineer, Planning Supervisor, quantity surveyor and cost consultant)."

Jan 1, 2005

By Abid Adekunte

Traditionally, designers and contractors provide additional external supports to retaining walls through the use of tie-back anchors or braces. Both approaches are known to have their shortcomings; braces limit working space within excavation areas, while tie-backs are seldom used in built-up areas where intrusion into adjacent property of non-cooperative owners has to be avoided or in situations where sensitive structures exist behind the wall. This paper focuses on the design, construction and monitoring of deep excavation support systems on two separate projects located in different ground conditions in the Republic of Ireland. On both projects, conventional ground anchorage and propping were inapplicable. This led to the development and application of two different novel solutions on both projects. Methods of wall performance monitoring on both sites also differ. Wall monitoring results show these innovative methods to be safe and effective. Advantages of the novel solutions over traditional approaches are highlighted.

Jan 1, 2010

By Fabio Santillan, Michael F. Zoccola

"Wolf Creek Dam and Lake Cum berland in Russell County Kentucky is operated by the United States Army Corps of Engineers (USAGE) Nashville District It is a combination 3,940 ft long (1,200 m) non-zoned clay embankment, a maximum of 215 ft (65.5 m) above top of rock and 1,796 ft long (547 m) concrete gravity section. Built in the 1940s, the limestone beneath the embankment is characterized by an extensive interconnected network of solution feature; varying from fist size to largecaves.In 2005, studies conducted by the Nashville Distrect concluded that a new seepage cut-off wall was needed as the existing cut-off wall, installed in the 1970s, did not go deep enough and did not extend laterally far enough to intercept all major karst features The dam was classified as a ""Dam Safety Action Classification I (DSAC 1) – Urgent and Compelling,"" the highest risk under USAGE risk category rankings. Also in 2005, under a USAGE risk screening program of its entire dam portfolio, Wolf Creek was classified as a Dam Safety Action Classification 1-Urgent and Compelling, which put it in the highest category. In 2007, an Independent External Peer Review from outside USAGE, concluded there was compelling evidence that a piping failure mode had re-initiated and was in an ""advanced continuation"" stage of development.Impounding approximately 6 million acre-ft (7.4x102m3) of water at flood storage, Lake Cumberland is the largest reservoir east of the Mississippi River and ninth largest in the United States. Catastrophic failure would result in widespread flooding, Ices of life and economic losses in billions of dollars.In 2008, the Nashville District partnered with a joint venture between finns Treviicos and Soletanche (ISM through a ""Best Value"" contract to construct a new seepage barrier wall. This acquisition method was used in lieu of a low bid contract due to complexity of the work and dam safety concerns. It took advantage of the experience and innovation of contractors by soliciting technical proposals that were evaluated independent of cost. Those proposals deemed technically qualified and responsive then underwent a trade-off analysis between ccst and technical approach and a selection was made of the one deemed to give the best combination."

Jan 1, 2013

By Aly M. Mohammad

The Howland Hook Terminal Facility located in Staten Island, New York is one of the most active container terminals in the Northeast United States. Due to the high capacity of the facility, the Port Authority of New York and New Jersey (PANYNJ) recently acquired the adjacent 37-acre Port Ivory Facility. Expansion of this Site facilitates the additional transfer of goods for rail transport, where formerly the facility was solely highway transport. Upon completion, the facility will have the ability to transfer containers directly to a freight rail line onsite by crossing from Howland Hook Site to the Port Ivory Site via a proposed bridge over Bridge Creek. The geology of the Port Ivory Site consists of shallow glacial deposits left by the leading edge of the last advance of the Wisconsin Glacier. Glacial and marine action over the millennia and the modifications of past construction combined to form a challenging site geologically. Prior to the PANYNJ acquiring the site, the Port Ivory Facility was occupied by Proctor and Gamble for nearly 100 years. Over the course of time, the site has had a variety of structures constructed and demolished at the site. The earliest structures were often supported on shallow foundations and the foundation types used progressed over the years transitioning from low capacity timber piles to various new pile types as they became available; such as Raymond tapered piles, steel piles with concrete cores, precast piles and cast in place foundations. Currently, we are designing 4-foot diameter high capacity drilled shafts to support a new bridge over Bridge Creek to connect the two sites. Drilled shafts proved to be a very economical solution from both a design and construction point of view to carry the axial load of the bridge of approximately 400 tons per shaft. The paper will present a historical evolution of the progress of deep foundation types used at the Port Ivory Site; from low capacity timber piles to high capacity large diameter drilled shafts. The paper will also present changes and modifications of geotechnical design criteria over time that affects the type of deep foundations used. For instance, utilizing new seismic design criteria requires selecting a deep foundation system that withstands seismic loading conditions and overcomes the effects of liquefaction.

Jan 1, 2004

By Dario Libano, Franz-Werner Gerressen

"Diaphragm walls are known as underground structural elements commonly used for retention systems and permanent foundation walls or elements. Of course they can also be used as deep groundwater barriers. This paper will focus on the construction work in an urban area like Sao Paulo. The Line 5 of Metro Sao Paulo is one of four network expansion projects undertaken at the same time. The projects will cover various areas of the city. The Line 5 on São Paulo’s south-side will be extended 7.1mi (11.5km) to serve 770,000 riders per day, stretching a total of 12.4mi (19.9km) along 17 stations. The extension line will facilitate access to the city’s central section and the commercial and hospital districts located along the line. The Brooklin Station, subject of this paper, had to be carried out in a special five shaft shape design, shaft diameter 131ft (40m) each, without using ground anchors. A focus will be taken on the special requirements of the installation of the arrows as well as on the specialties of installation for the shaft shaped layout. Therefore, it was required to install a 3.3ft (1,000mm) diaphragm wall using a specific layout especially in the connecting sections of the shafts, the so called arrows, to provide a bearing area for the struts. Maximum wall depth was about 121ft (37m); the total volume was about 20,060 cubic yard (15,337m³). The paper will describe the construction method and the sequence of activities required for the construction of this diaphragm wall using a combination of hydraulic grab and trench cutter system.INTRODUCTIONThe Line 5 Extension, in the city of Sao Paulo/Brazil, is currently the most important investment in public transport by Sao Paulo state’s government. It will connect the south part of the city to the city center, crossing through four other major METRO lines and stations, all currently in operation. The extension includes a new parking yard for the trains and 11 new stations. The Brooklin Station is one of the new stations and has a unique geometry of five secant shafts. The station should open and operate in 2016.The original design included constructing five secant shafts stabilized by two plastic slurry walls using conventional grab technology. One of them was to contain the contamination plumes in the neighborhood and the other for temporary support to enable the excavation of the shafts. The final retaining wall design was reviewed and changed to a concrete structural diaphragm wall. The reason of design change was as well the reduction of construction time of the shafts by half to meet the schedule as to avoid dewatering effects in a geological region characterized by Quaternary sediments and environmental contamination plumes. It was the first time that a trench cutter (hydromill) was used in such a situation in Brazil. The cutter increased the quality of the joints by overcutting, and decreased the probability of having seepage into the shafts. The cutter created a seepage barrier and avoided movement of contamination."

Jan 1, 2017

By Terry Eldridge, Keith MacKay, David Siddle, Luke Moger

On August 4th, 2014, a breach occurred in the Perimeter Embankment of the Tailings Storage Facility (TSF) located at the Mount Polley Mine, releasing approximately 10.6 million m3 of supernatant water, 7.3 million m3 of tailings solids, 6.5 million m3 of tailings interstitial water and 0.6 million m3of construction materials. A Temporary Upstream Rockfill Berm was constructed between August 2014 and February 2015 within the area of the tailings dam failure in order to retain the remaining tailings solids during the low flows of the winter season. The Temporary Upstream Rockfill Berm was constructed as part of the initial response phase, with the primary objective to abate the flow of tailings into the receiving environment. A secondary objective of its construction was facilitating the required investigation works downstream of the tailings dam failure. The selection of the coarse grained material used in the construction of the Temporary Upstream Rockfill Berm was based on the availability of the material (timeliness of construction) and the non-water retaining design of this initial response phase. Consequently, an alternative method was required in order to prevent further loss of mine-affected water and tailings from the TSF, as well as to provide short-term contingency water storage, during high flow conditions expected in late spring. Golder Associates Ltd. designed the 2015 Freshet Management Embankment, a deep mixing cut-off wall, to meet these site requirements, which was constructed by Mount Polley Mining Corporation and Golder Construction Inc. between December 2015 and April 2015. The works included 132 soil cement panels constructed to depths of up to 27 meters. This aspect of the works was completed using an RG25S Bauer CSM rig on a 24 hour per day, 7 day per week schedule. The cut-off wall specifications included a target unconfined compressional strength (UCS) of between 1 and 2 MPa, a maximum hydraulic conductivity of 1x10-6 cm/s, and a ductility to enable the soil cement to undergo a minimum of 5% strain without a reduction in strength or increase in hydraulic conductivity. In order to control and assure the quality of the soil cement, 2553 wet grab specimens were retrieved from the fresh soil cement panels using a project-developed sampler. Four of the soil cement panels were cored with a mud-rotary drill rig and optical and acoustic televiewers were placed into the boreholes in order to log several relevant parameters, including image, texture, relative hardness, borehole-shape, and temperature.

Jan 1, 2016

By Prakash Annamalai Rangasamy, Muthukkumaran Kasinathan

"Infrastructure development like elevated expressways, metro train and flyover are required proper foundation system to carry heavy traffic loads/significant lateral load, especially in the presence of hard stratum at shallow depth. Pile foundation under bridge pier system is widely adopted in metro projects where the piles are essentially socketed in rock. However, the drilling in hard rock is a time consuming process and needs heavy machineries which lead to delay in construction activities. In the present study, the influence of free standing height on rock socketing under lateral load is investigated. The experiments were conducted on an instrumented model pile with varying depth of socketing and for varying Lf/D ratios. The experimental results shows the load carrying capacity of the pile increases by increase in Lf/D ratio, where in the case pile without socketing (bearing on rock) is compared with 3D depth of socketing. Thus socketing the pile provides significant benefits on carrying capacity of lateral loads. Embedding the pile into hard strata reduces the lateral displacements substantially compared with pile bearing over hard strata. Form the study, it is noticed that the influence of rock socketing has significant effect in the lateral load capacity. And also, the effect of free sanding height play a major role in the lateral load capacity of the rock socketed piles.1. INTRODUCTIONA substructure carrying heavy lateral load at shallow depth, the structure has to be socketed into hard strata to enhance the efficiency of load carrying capacity. The existing field practice is to socket the end bearing piles in hard strata over a minimum depth of four times the diameter of the pile based on rock classification (IS 14593:1998). Reese (1997) developed p-y curves for analysing drilled shafts in rock under lateral loading, based on strong and weak rock criteria. The proposed p-y curve approach has the ability to simulate the nonlinearity and non-homogeneity of the rock mass surrounding the drilled shaft. Gabr et al. (2002) proposed a hyperbolic p-y criterion based on field tests on small diameter drilled socketed shafts. By considering pile as linearly elastic semi-infinite space and soil as homogeneous isotropic material, Poulos (1971) proposed solution to determine the horizontal displacement and pile head rotation. Poulos (1972) extended this elastic continuum approach to give an approximate solution by considering drilled shaft and pile bearing on rock as fixed and pinned end boundary condition. Zhang et al. (2000) developed a non-linear continuum approach for drilled shafts in a soil and rock mass by considering the effect of soil and/or rock mass yielding on the behaviour of shafts. Randolph (1981) conducted a parametric study on the response of laterally loaded piles embedded in an elastic soil continuum. The study was conducted using the finite element method and the results were fitted with closed-form expressions from which the lateral responses of piles were calculated. The solutions given by Randolph (1981) were expanded by Carter and Kulhawy (1992) from the results of finite element studies on the behaviour of laterally loaded flexible and rigid drilled shafts in rock. Desai and Christian (1977) gave a finite difference program to solve rock socketed problems by considering soil and rock mass as elastic-perfectly plastic. Zhang et al. (2000) verified the proposed finite difference method with existing field test results. Gabr et al. (2002) and Liang and Yang (2006) proposed hyperbolic p-y curves based on filed test results and verified with finite element programs. However the need of field and lab scale experimental studies to validate the existing methods of analysis is necessary."

Jan 1, 2015