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By Roberto Nova

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

Jan 1, 2008

By Peter J. Nicholson

Recognition of the liquefaction susceptibility of dam embankments has been heightened since the San Fernando Dam near failure incident in 1971. Both the downstream and upstream slopes of dams can be at risk for slope failure that can lead to breaching of the dam during or after a seismic event. Many dams have been remediated by various means such as the installation of stone columns or by excavation and replacement of the liquefaction susceptible material. Recent engineering and technology advances in equipment and materials has shown that construction of shear walls to the appropriate depths and at the right center to center spacing may be an economical alternative to the more traditional methods. Recently, the downstream embankments of at least 4 dams, from South Carolina to California, have been, or in the process of being remediated by the use of shear walls. The method of installation has been either multi-axis Cement Deep Soil Mixing walls or walls constructed by the use of trench excavation under self-hardening slurry. Four case histories of dam remediation are discussed, three by multi-axis paddle auger CDSM equipment one with the use of self hardening slurry trenches.

Jan 1, 2008

By Michael D. Justason

This paper describes the technology behind the development of an automated energy control system for a diesel pile hammer. Some background is given on experience using an energy monitoring system on the Route 1/I-95 interchange in Alexandria, Virginia. An adjustable hammer throttle and feedback from an energy monitoring system was then used to create a fully automated hammer energy control system. The performance of this system is described in reference to a piling project in Canada where the automated energy control system was used to obtain an unprecedented level of quality control and assurance ? data and graphs from the project are presented. The hammer energy control system (ECS) was used to successfully control and maintain a prescribed impact energy for the diesel hammer. This paper presents the first ever results from a truly automated diesel pile hammer and points to a new direction in quality control and assurance in pile driving.

Jan 1, 2006

By Allan Herse

"The years following World War II were nation building years in Australia. Soldiers returned from the European and Asian theatres of war sparking a major infrastructure construction boom. Dams and highways were built to keep up with the growth of towns and cities, which were bursting at the seams, not just from the returning soldiers settling down with their families but also from the many waves of refugees from war torn areas around the globe.The demand for electricity generation and distribution required for the growing population sparked the expansion of the national power grid with new high-voltage transmission towers appearing across the landscape. However, with an original design life of 50 years, those transmission lines constructed in the 1950s are nearing, or are at the end of, their anticipated service life.In recent years, the Australian power distribution network has changed from a period of high construction activity in greenfield high-voltage lines to a period that is now focused on reducing cost and maintaining existing assets. Replacing aboveground structural members and electrical components is relatively simple even under live conditions. However, the replacement or repair of tower foundations, many of which are in remote locations, has been a problem that has caused difficulties for power utilities trying to operate on a budget while also avoiding costly and unpopular power outages.With thousands of miles of aging transmission lines needing life extension work, Piling & Civil Australia (PCA) has developed a patented system of upgrading the foundations with micropiles while under live-line conditions without requiring costly outages. The system is seen as revolutionary by power utilities, allowing the utilities to extend the life of their existing assets until demand increases to warrant the construction of a new line. PCA has been working on a potential solution with Powerlink Queensland for the past 5 years to develop a quick and cost-effective foundation replacement system that can extend the life of its existing asset base anywhere from an additional 5 years to 50 years.With design support from Quanta Subsurface, USA, PCA recently completed the foundation replacement of 26 lattice tower foundations in the Townsville region of North Queensland. Using a steel bracket (patent pending) to connect hollow bar micropiles to the lattice towers, the installation techniques that were developed enabled the micropiles to be installed within a tolerance of less than about 3/8 in (10 mm) through the existing steel grillage foundation while maintaining live line conditions. The project was an Australian first and a trial by Powerlink for wider use within its network, and it was delivered on time and within budget at one tenth of the cost of traditional methods."

Jan 1, 2017

By Allan Herse

"The years following World War II were nation building years in Australia. Soldiers returned from the European and Asian theatres of war sparking a major infrastructure construction boom. Dams and highways were built to keep up with the growth of towns and cities, which were bursting at the seams, not just from the returning soldiers settling down with their families but also from the many waves of refugees from war torn areas around the globe.The demand for electricity generation and distribution required for the growing population sparked the expansion of the national power grid with new high-voltage transmission towers appearing across the landscape. However, with an original design life of 50 years, those transmission lines constructed in the 1950s are nearing, or are at the end of, their anticipated service life.In recent years, the Australian power distribution network has changed from a period of high construction activity in greenfield high-voltage lines to a period that is now focused on reducing cost and maintaining existing assets. Replacing aboveground structural members and electrical components is relatively simple even under live conditions. However, the replacement or repair of tower foundations, many of which are in remote locations, has been a problem that has caused difficulties for power utilities trying to operate on a budget while also avoiding costly and unpopular power outages. With thousands of miles of aging transmission lines needing life extension work, Piling & Civil Australia (PCA) has developed a patented system of upgrading the foundations with micropiles while under live-line conditions without requiring costly outages. The system is seen as revolutionary by power utilities, allowing the utilities to extend the life of their existing assets until demand increases to warrant the construction of a new line. PCA has been working on a potential solution with Powerlink Queensland for the past 5 years to develop a quick and cost-effective foundation replacement system that can extend the life of its existing asset base anywhere from an additional 5 years to 50 years.With design support from Quanta Subsurface, USA, PCA recently completed the foundation replacement of 26 lattice tower foundations in the Townsville region of North Queensland. Using a steel bracket (patent pending) to connect hollow bar micropiles to the lattice towers, the installation techniques that were developed enabled the micropiles to be installed within a tolerance of less than about 3/8 in (10 mm) through the existing steel grillage foundation while maintaining live line conditions. The project was an Australian first and a trial by Powerlink for wider use within its network, and it was delivered on time and within budget at one tenth of the cost of traditional methods."

Jan 1, 2017

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

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

Jan 1, 2015

By Emre Biringen

Over the past decades, there has been an increasing recognition of the strategic use of pile-supported rafts in design of heavily-loaded structures to reduce total and differential settlements. However, such a hybrid foundation construction method has not been widely utilized in many countries, including the U.S., due to code limitations. In current practice, the foundation design is based on either (i) the bearing capacity of the raft supported by the subgrade soils, or (ii) solely the pile capacity. This paper addresses the potential use of such hybrid piled-raft systems, where the structural load is shared by both by the piles and the subgrade soils directly beneath the raft, in foundation design of power plant structures. The study assessed some of the characteristics of piled-raft behavior by undertaking three-dimensional finite element analyses of two raft sizes, and various pile layout patterns, including the rafts with piles distributed evenly and only in the central area of the raft. The computer software PLAXIS 3D with the Mohr-Coulomb constitutive soil model was used to facilitate the modeling of such cases. The results presented in this paper indicate how strategically locating the piles could reduce the differential and total settlements.

By Sherif Elfass, Gary Norris

Bi-directional load testing of drilled shafts has been widely adopted as a means to evaluate their load carrying capacity. However, in order to reach failure, most of these tests are carried out on sacrificial shafts using expensive sacrificial elements such as hydraulic jacks. A proposed low-cost bi-directional testing technique is discussed. It mechanically loads the end bearing soil below a drilled shaft, against its side shear resistance. The technique was originally established as an alternative to post-grouting to reliably account for the forfeited end bearing resistance. However, since it loads the shaft in a manner similar to conventional bi-directional tests, it can be used to not only load test sacrificial shafts, but production shafts as well. Furthermore, unlike conventional bi-directional load tests, the load is applied through surface jacks. These jacks, along with other load test components, are movable and can be reused to load test all the shafts of the project thus presenting an economic benefit. The concept of this technique has received favorable feedback from a few consulted departments of transportation, and while promising, has not been field tested to date. A U.S. patent was issued for the tip loading module and the loading technique described.

Sep 8, 2021

By P. D. Arumairaj, B. Vani

"Micropiles are small diameter cast insitu reinforced grouted piles and it has been effectively used in many applications of ground improvement. It increases the load carrying capacity of soil and reduces the settlement. It is also used in strengthening existing foundations. In this study, the effect of Solid and Hollow micropiles on the load carrying capacity of footing resting on sand is studied. The effects of solid Micropiles are investigated by conducting experimental model studies. The parameters involved in this study include the position of pile, pile length and pile spacing. Load test was carried out on a model footing resting on sand with solid and hollow micropiles. Load test trail is repeated for footing on Micropiles with varying lengths of 10, 20, and 30 times the diameter and spacing equal to 5, 4, 3, 2 times the diameter. The load-settlement behavior of each case is compared. Optimum length and optimum spacing of both the solid micropile and hollow micropile are determined. It is also observed that the effect of micropiles in the peripheral of footing resists lateral displacement of soil underneath the footing. The micropile beyond significant depth becomes redundant.INTRODUCTIONA micropile is a small diameter (less than 300 mm) drilled and grouted pile that is typically reinforced - FHWA-NHI 2005 (Federal Highway Administration-National Highway Institution). It is constructed by drilling a borehole, placing a steel reinforcing element into the borehole and grouting it. Hollow micropiles are typically reinforced by solid central bar that occupies about onethird of the hole volume. The grout is placed by gravity, under pressure methods or by a combination of both (post grouting). Thus, micropiles can be considered as small drilled-shafts that are specially drilled and grouted.Historically, micropiles have been introduced in Italy as a foundation system mainly for retrofitting and underpinning of structures that had sustained damage during World War II and access for conventional piling equipment was not possible (Bruce, 1988). The second generation of micropiles is a pressure grouted piles with a central mono all thread bar (with diameter up to 89 mm). They are installed by using either an open or cased hole drilling method.A new generation of micropiles, termed Grout injection bore micropiles (IBOR), was developed in the 1980s. The IBOR, currently named hollow bar micropiles, utilizes a continuous all-threaded hollow steel bar as the drilling and grouting conduit, which allows drilling and grouting simultaneously without the need of a casing during drilling. A sacrificial (lost) bit with openings that allow for pressure grouting of the hole is threaded onto the end of the hollow bar and is left in place following drilling. A drilling fluid (air, water, or grout) is introduced through the hollow bar and allows the spoils to flush from the borehole opening. Upon reaching the required depth, neat cement grout is then injected under high pressure into the drilled hole to fill the annulus between the bar and the soil from the bottom to the top. Due to the grouting method employed, the shape of the hollow bar micropile is expected to have a bulb shape with an enlarged base."

Jan 1, 2015

By James G. Ulinski, Sebastian Lobo-Guerrero, Vishal B. Patel

"Recently modified design equations used in the transportation industry to calculate side friction and end bearing capacity for drilled shafts are now providing more realistic estimations of capacities than did previous methods. Using multiple case studies and test results from various projects, a more realistic design approach was formulated by the Federal Highway Administration (FHWA), which resulted in greater values of ultimate capacity for side friction and end bearing and in a more efficient design overall.In 2010, the FHWA published GEC-10 – Drilled Shafts: Construction Procedures and LRFD Design Methods, which illustrates a different method of calculating side friction and end bearing resistance and results in greater values for design. In 2014, the Association of State Highway and Transportation Officials (AASHTO) adopted the method put forth by FHWA, which was included in its LRFD Bridge Design th Specifications, 7 Edition. The Pennsylvania Department of Transportation (PennDOT) recently adopted and incorporated the similar methodology as AASHTO for calculating side friction and end bearing for drilled shafts in rock, and these changes are reflected in the 2015 edition of the PennDOT Design Manual, Part 4 (DM-4). This article discusses the past and current design methodology along with a project case study with results from Osterberg Cell (O-cell) load testing, which presents a comparison between the design resistances of ultimate side friction and end bearing and the measured capacities at failure.The Old and the NewEditions of the AASHTO LRFD Bridge Design Manual from 2012 and earlier estimated ultimate side resistance, qs, in rock using the following equation (modified from Horvath and Kenney, 1979):qs=0.65aEpa(qu/pa)0.5 < 7.8pa(f ’c/pa)0.5 where: qu is the uniaxial compressive strength of the rock in ksf; pa is the atmospheric pressure in ksf; aE is the reduction factor to account for jointing in rock; and f ’c is the compressive strength of the concrete in ksi. For intact rock, previous versions of the AASHTO manual required that the ultimate end bearing resistance, qp, was calculated using the following equation: qp=2.5qu."

Jan 1, 2017

By Nagarajan. D, Raja Rajan. K, Vijayakumar. T

Major bridges crossing mighty rivers must be constructed in flowing water. Constructing the sub-structure in water has been a challenging job for contractor. Special construction techniques with marine fleets to be adopted for waterfront construction. Enabling works like temporary piling platform and cofferdam used for pile and pile cap construction. Apart from this, enabling works like load out jetty to transport the materials from land to water; temporary walkway for access of workman to work location; temporary access bridge for construction vehicles movement; temporary liners for tower crane foundation; Concrete block to act as dead man anchor for barge movements were all required by the contractor for smooth functioning of site as per construction schedule. Investment in enabling works by contractor plays a significant role on profit margin of the project and of course with utmost safety. Design of enabling works for waterfront structures involves hydrological data like afflux, bathymetry survey, current force, scour depth and wave force to be taken cautiously for safe and economic design. Type of foundation and pile/well cap top level corresponding to water levels shall influence the construction scheme. Usage of geotechnical software like Wallap and Plaxis required for enabling work design to enhance the safety of the structure. Bathymetry and soil condition play a critical role in design and construction of enabling works. Water Discharge quantity in river along with water levels like low water level, high flood level, seasonal fluctuation of water levels has a great impact on design of enabling works. Establishing enabling works for waterfront construction near to an existing bridge is an additional challenge for the contractor. Along with design, constructing the enabling works in water requires special construction methodology and sequence of work. This paper shall provide insights on overview of design and construction of enabling works for waterfront construction.

Nov 1, 2022

By Rakam Lama Tamang, Michael J. Byle, Stephen Ernst

"For various reasons, dredging may become necessary in front of existing bulkhead walls, either for channel deepening or for environmental remediation of contaminated sediments. The removal of sediments at the base of bulkhead walls removes support for the toe of the wall that must be assessed. Evaluation of this impact can be problematic for aging bulkheads for which no design or construction records exist. This paper will address the steps that should be taken in investigation and analysis to assure proper assessment and means to address uncertainties and gaps in information. The steps include pre-investigation data review, field inspection, geotechnical and geophysical investigation tools, parametric analysis and design tools. Examples from several bulkhead assessment projects will be provided that include a variety of conditions and tools for application. The focus of the paper will be on the integration of technologies to assess bulkhead geometry, geotechnical properties and stability, structural safety and constructability issues with removal of support, and means of temporary and permanent stabilization for environmental applications.IntroductionBulkheads and quays have existed as long as there have been waterfront activities. Some of the earliest date back to 1200 B.C.E.(Raban, 1987), however in the United States few predate the eighteenth century. Most extant bulkhead structures, and all steel sheet pile bulkhead walls date from the early 20th century or later. These structures function to protect the shore from erosion, support landside activities, and serve as place to moor and offload vessels. Regardless of the age or usage of existing bulkheads, it is essential to assess and protect them if needed where removal of soils on the water side of the bulkheads is planned to dredging.Waterfront BulkheadsExisting bulkhead structures can be classified into two types: Cantilevered, and anchored. Cantilevered walls are completely supported by the soil on the water side, while anchored bulkheads are supported both by the soil on the water side and anchorage on the land side (Figure 1). Walls may be constructed of timber, steel, or concrete. Timber walls may be lagging with soldier piles, cribbing with soldier piles, or timber sheeted such as Wakefield walls (Figure 2). Steel bulkheads are most commonly constructed using sheet piling comprised of interlocking A or Z shapes, though some historic walls were constructed with flat sheets. Precast concrete sheet piling has also been used in construction of bulkhead walls. Anchorage may be provided by steel bars or tendons attached to deadmen, sheet piling, driven piles, or earth anchors."

Jan 1, 2017

By D. M. Holloway

As a part of the 1-15 Reconstruction Project, static and dynamic (high-strain) testing methods formed the basis to estimate long-term axial capacities, and to assess the magnitudes of bearing capacity gains (setup) from the end of installation to the time of static/dynamic tests weeks later. This paper summarizes the results of nine full scale pile load tests to failure in compression, and how the designers used these data to finalize pile selection and penetration criteria bridge-by-bridge in the final design stages. Soil conditions along the project alignment ranged from deep, lightly over-consolidated Lake Bonneville clays interbedded with granular strata of varying consistency, to sites dominated by dense alluvial deposits of cohesionless soils well above the water table. The test sites were selected to bracket the conditions that are expected. Twelve-, 16-, and 24-inch-OD pipe piles are to be used to support the new bridges. The team plans to impact-drive all piles closed-end to final penetrations. The test piles varied from 35-ft-long pipes driven to refusal in the shallow dense sands at some sites, to 115-ft-long pipes stopping at 3 blows per foot in predominantly cohesive deposits. The capacities gained with time proved to be reasonably predictable, and significant setup was noted both in the cohesive and cohesionless strata. The test program objectives included providing the means to estimate long-term capacities from short-term (24- to 48-hour) restrikes following installation of foundation piles during production driving operations.

Jan 1, 1998

By C. M. Haberfield

"1 INTRODUCTION Around the world, there is a demand for larger structures, tall buildings and large bridges. While good footing design is important for all structures, it is even more important in the case of large structures. Recent experience with footing design for tall buildings (e.g. Burj Al Alam development and Nakheel Tower in Dubai, the Gate of Kuwait in Kuwait, the City Centre Project in Bahrain and Eureka Tower and Freshwater Place in Melbourne) has shown the benefits of investing in footing planning, design and construction (Haberfield, 2011, Poulos and Bunce, 2007). The footing systems for most of these projects include the use of deep bored piles or barrettes (piles of rectangular cross-section). Many use piled rafts where the piles, while acting to support the load, are primarily used to reduce settlements. A clear understanding of the factors controlling the behaviour of the footing system is needed to enable a good engineering design to be achieved. This starts with a sound understanding of the ground characteristics and individual pile performance, including adequate collection of data and testing. The best footing solution can then be found using recent improvements in data collection and analytical techniques, complex and highly capable computer-based models and the availability of high speed computers. This paper focuses on the axial performance of deep bored piles socketed into rock – both their individual performance and their performance as part of a larger footing system. Recent research and construction practice is discussed. In practically all cases, serviceability conditions control the behaviour of the footings. Methods of establishing the parameters for input into sophisticated computer programs are described. Application of the methods to case studies is included and it is shown that the behaviour of individual piles can be closely predicted. These developments lead to lower construction costs, better constructability and shortened construction time because of the better understanding of footing behaviour. 2 FACTORS AFFECTING PERFORMANCE OF FOOTINGS ON ROCK For a typical pile-supported footing, it is necessary to consider both individual pile, pile group and raft performance. These require consideration of the behaviour of the ground immediately beneath the surface raft or footing, along the pile shaft, and at and beneath the pile toe (Figure 1). Immediately beneath the surface raft or footing, the important factors are strength for bearing capacity and stiffness for settlement and interaction effects. Along the pile shaft, of most interest are strength for bearing, excavatability and stability; stiffness for settlement and interaction effects; geology and permeability for pile stability and, most importantly, pile shaft resistance. At the pile toe all the above factors for the pile shaft are present and in addition the pile end bearing is of interest. Below the toe, stiffness for pile settlement is important to at least a depth of twice the building width."

Jan 1, 1900

By K. E. Darnell

Drilled pier foundations have long been a favored foundation type for heavily loaded structures. Drilled piers derive their load-bearing capacity from end-bearing, and/or sidewall friction. This type of foundation is used in many geologic settings, including those areas underlain by hard carbonate rock, such as limestones and dolomites. When properly designed and constructed, drilled piers provide high load-carrying capacity in both compression and uplift. However, carbonate rock is often subject to intense differential weathering resulting in the formation of an irregular bedrock surface, sinkholes and caves; consequently, the investigation for, and the design of, drilled pier foundations is often complex. Further, the construction may be difficult and costly. This paper discusses geotechnical investigative procedures which can be employed to develop foundation design criteria and reduce the frequency of changed conditions. Finally, state-of-the-art construction practices and quality control techniques are discussed.

Jan 1, 2010

By Don W. Dotson

In 1962, Kondner prepared several papers dealing with hyperbolic stress-strain response of cohesive soils. The following year, Brinch Hansen proposed 80% and 90% failure criteria for stress-strain behavior of cohesive soils. Fellenius was instrumental in popularizing these failure criteria for pile load tests and offered a direct solution equation for the failure load according to the 80% failure criterion. Since the 90% Criterion has been incorporated into the International Building Code, equations for the direct solution of the failure load at the 90% Criterion would be useful to practicing engineers. This Technical Note supplies the derivation methodology for the 80% Criterion and provides expressions to determine the load and deflection at failure for the 90% Criterion.

Aug 1, 2013

By Frédéric Rocher-Lacoste

On July 2nd, 2007, LCPC and LOADTEST performed a static loading test with an Osterberg-cell on a bored pile of 1600 mm diameter. The 56.50 meters deep test pile constructed by Trevi Spa for Soares da Costa group, was near the Cacheu river in Guinea Bissau. This test was conducted to validate the design of the foundations of the Sao Vicente bridge; a project undertaken by the Ministry of Public Works of the Republic of Guinea Bissau and funded by the European Development Fund. Sub-surface conditions at the test pile location consist primarily of layers of weak sands and clays. The piles were loaded statically using the O-cell® bi-directional method 25 days after concreting. The maximum sustained bi-directional load applied to the pile was 11.7 MN. At the maximum load, the displacements above and below the O-cell assembly were 6.6 mm and 81.9 mm, respectively. The resulting pile head behavior has been calculated for a combined skin friction and end-bearing load of 29.3 MN. The piles were also instrumented using LCPC removable extensometers, which made it possible to measure the mobilization of shaft friction and toe resistance. The adjusted test data indicated that this pile would settle approximately 12.2 mm for the service load of 12MN applied at the head of the pile. This paper provides a very brief presentation of the bridge project and the test pile instrumentation: LCPC removable extensometers and O-cell® instrumentation. The results are detailed and analyzed herein and the combined use of these two instrumentation systems is a world première.

Jan 1, 2008

Jan 1, 1992

By Yuji Yamashita, Kazuyoshi Kamimura, Tsuyoshi Takahashi, Naoya Matayoshi

"The CDM-LODIC method (cement deep mixing - low displacement and control) method enables ground displacement to be reduced by removing an amount of soil equivalent to that of injected cement slurry and the volume of the plunged mixing tool, which causes a certain degree of ground displacement. Since the CDM-LODIC method was developed in 1985, it has been applied to over 930 sites and the accumulated volume of stabilized soil has now reached 7.6 million cubic meters.In the CDM method, the number of blade rotations per unit depth in the ground when the mixing blades are withdrawn is considered a construction item. The blade rotation number depends on the degree of mixing between the cement slurry and the ground Some field tests were performed based on the degree of mixing between the cement slurry and the ground. In these tests, a new concept of evaluating the blade rotation number when the screw rod penetrates to a given depth without injecting cement slurry has contributed to the degree of mixing. Furthermore, a correlation exists between the coefficient of efficiency of soil removal and the cement slurry admixture rate. In this paper, we discus the data collected in those field tests and present some application examples.OUTLINE OF CDM-LODIC METHODThe injection of cement slurry may cause some ground displacement during Cement Deep Mixing (CDM). In recent years, due to an increased demand for ground improvement work in urban areas, there is increased concern that buildings near any CDM site may be adversely affected. The deep mixing method which reduces displacement due to mixing (CDM-LODIC method) enables ground displacement to be minimized by removing an amount of soil equivalent to the injected cement slurry and the volume of the mixing tool, which itself causes some ground displacement. When the construction site is near other structures, regardless of whether on or under the ground, the CDM-LODIC method can be used in order to minimize any ground displacement. There are considered to be two main causes of ground displacement as shown in Figure 1. Displacement A indicates ground displacement caused by the volume of the inserted mixing tool during the penetration stage and displacement B indicates ground displacement caused by the volume of the injected stabilizing agent. Thus, by removing soil equivalent to the volume of the inserted mixing tool and the injected stabilizing agent, ground displacement can theoretically be minimized. Figure 2 shows the amount of observed ground displacement in the cases of CDM and CDM-LODIC at an actual site. These case studies indicate that ground displacement can be reduced by removing the soil."

Jan 1, 2015

By Peter J. Jancich

This paper describes the installation of high capacity Augered Pressure Grouted piles which support structural loading from a four level parking garage in west-central DuPage County, Illinois. The subject site is characterized by a variable glacial geology which presented, to the designer, a number of problems with respect to analysis and prediction of pile capacities, and, to the contractor, the very real difficulties associated with estimating the costs of, and installing foundation units in highly variable subsurface conditions. 2. General Site and Subsurface Conditions 2.1 Site Conditions - The subject site is part of an overall 300 acre property. Topographically, the overall site is saddle shaped with higher elevations along north and south boundaries and a subdued, east-west trending swale centrally located. Elevation relief is on the order of 25-30 feet (7.6-9.2m).

Jan 1, 1991