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By Emad Farouz, Ehab S. Shatnawi, Charles Winter

The increasing demand for small deformations and high-capacity drilled shafts without enlarging drilled-shaft diameters has motivated the development and increased use of a base grouting (BG) technique. This technique has been demonstrated to improve drilled-shaft axial capacity, especially for shafts tipped into loose cohesionless soils. To date, there are a couple of documented design methods for estimating the axial geotechnical resistance of base-grouted shafts. However, there is no or lack of research that addresses the lateral response of such shafts. A base-grouted drilled shaft test program was carried out during the design phase of the Wisconsin I-94 Zoo Interchange reconstruction project. The test program included installing and testing one base-grouted shaft and one ungrouted shaft under both lateral and axial loading. Based on test results, it was concluded that the lateral behavior of the BG drilled shaft is significantly stiffer than conventional drilled shaft . Hypothetical method was developed to account for potential increased, however, the method should be verified with more lateral load test.

By Ting-Wei Wang, Yung-Wen Chen

Artificial ground freezing is commonly used globally during excavation of shield tunnels and for groundwater control. It is a special construction method for temporary ground improvement that involves introducing coolant into underground pipes to freeze water in the soil. The frozen soil is cemented together as a result to form a frozen wall, which provides high strength and low permeability. Once the thickness of the ice wall reaches design requirements, underground excavation can be conducted with the coolant removed afterward to return the soil to its original state. This technique is cost-effective in scenarios where complete groundwater cut-off and excavation support are required; where work is deep underground and faces difficult ground conditions and where access restrictions limit the use of other displacement-type ground improvement techniques. Due to the demand for shield tunnel construction for utilities in Taiwan, ground freezing has become an important soil stabilization method there. In this article, we will share two brine freezing case studies and an in situ liquid nitrogen experiment that was conducted to develop this technique.

Feb 1, 2022

By George Onorato, Giovanni Bonita

Deep soil mixing (DSM) has now become a ubiquitous ground improvement technique across the globe for producing soil-cementous materials for many types of complex civil and environmental applications. In the field, the cementation bonds of the soil-cement materials are formed under a confining stress conditions; however, these conditions are generally not considered as most wet grab specimens are cured and tested under ambient atmospheric conditions. This has led to an underestimation of the engineering and mechanical properties of the soil-cement mixed material. This paper presents the preliminary findings of the effect of confining stresses on the mechanical properties of soil-cement mixed samples. This paper discusses the specialized field techniques used for modeling confining stresses during curing and presents the preliminary findings from different soil types. The findings indicate a strength increase within samples cured under a confining stress relative to nonconsolidated samples. The magnitude of the strength increase also appears to be different for different soil types. Finer-grained soils appear to exhibit a larger relative strength increase with confining stress relative to predominately granular soils.

By Timothy C. Siegel

Drilled displacement piles (also known as augered cast-in-place displacement piles or augured, pressure grouted displacement piles) are installed by the displacement of soil and subsequent placement of fluid cement grout within the evacuated volume. Depending on the soil grain-size characteristics, soil behavior, in situ soil density, pile spacing, and pile diameter, the installation process can result in measurable densification and an increase in lateral stress. This paper examines the conditions prior to and following the installation of drilled displacement piles at sandy sites using the cone penetration test. The data support that the installation of drilled displacement piles results in a substantial increase in tip resistance.

Jan 1, 2007

By Mohammad T. Izadi

Piles are, often, used for transferring load from the super structure through soft consolidating strata onto relatively stiff uncompressible soils. Downward movement of the soft soil strata develops negative skin friction and dragload around the pile shaft, with time. Traditionally the induced dragload is considered in determining the pile bearing capacity. On the other hand, field measurements on instrumented piles show that negative skin friction is reduced by the magnitude of applied live load. A method for calculating the pile bearing capacity, driven through soft consolidating strata is presented. In this method, two allowable load-bearing capacities are calculated for each pile, live load plus dead load and dead load. The proposed method, substantially, increases the allowable load bearing capacity of piles compared to calculated values by the traditional methods.

Jan 1, 2001

By P. Davies

The Hillside Smelter presently under construction at Richards Bay, Republic of South Africa, will be, on completion, the fifth largest aluminium smelter in the world. The site selected for this plant is underlain by sandy soils of variable density to depths of 30m or greater. In order to firmly establish pile founding depths required for alternative pile types in the variable subsurface conditions prevailing across the site, a pre-construction test piling programme was conducted incorporating piles instrumented with resistance strain gauges. The results allowed analysis of the relative contributions of end-bearing and shaft friction to the overall bearing capacity of each pile type and permitted comparison with the predictions of conventional static bearing capacity analyses. Conformance with acceptance criteria in respect of allowable pile head movements for single piles was also examined.

Jan 1, 1996

By Mustapha Zergoun

This paper presents the results of load tests to assess the vertical load carrying capacity of concrete expanded base piles, or pressure injected footings, for various projects located near Vancouver, British Columbia, Canada. The site subsurface conditions and load test methods are described for the Vancouver International Airport site and the test results are reviewed under both compression and tension loading conditions. The pile load tests at Vancouver International Airport are compared to load tests at other sites near Vancouver. The pile load test results are reviewed with respect to available methods of estimating the vertical capacity of this type of piles. The effect of ground improvement by densification on the load test results is considered. The limitations of tension load tests on single piles with respect to uplift resistance of pile groups under seismic conditions are pointed out. Recommendations are proposed regarding pile load test methodology to estimate ultimate vertical load carrying capacity of plies for limit state design.

Jan 1, 2004

By Ray Zelinski

Caltrans sponsored a research project in 1992 which incorporated proprietary and generic pile types. The piles were subjected to axial tensile/compressive loads in deep, soft soils. Descriptions of various pile types and systems, scenarios leading to the proposal to test the systems, and load test results were/will be provided by other presenters at this seminar. Therefore, this paper will focus on the issues surrounding use of test results and proprietary pile systems on Caltrans construction projects. The primary issues facing Caltrans during implementation are as follows: 1) producing pile cap designs for a range of pile types and loads; 2) providing construction specifications which allow fair competition among the system vendors, yet assure design and ultimate capacities; 3) Develop quality control standards for pile system materials and installation techniques which guarantee pile durability for static and dynamic loads; and 4) assure that foundations have adequate lateral capacity.

Jan 1, 1993

By James Warner

Although use of low mobility grout is just now beginning in some parts of the world, its advantage for many applications has been well established through more than 50 years of positive experience. The single largest area of application continues to be densification of soil by way of compaction grouting. Because it is often the safest and least costly method for soil improvement in general, and virtually always that in connection with soil improvement under, or adjacent to structures or in developed areas, use will undoubtedly increase both geographically and in diversity of application.

Feb 10, 2003

By Kimberly Martin

The EFFC/DFI Carbon Calculator provides the deep foundations industry the opportunity to be a leader when it comes to carbon reduction. This tool was created 10 years ago in an extensive effort by the European Federation of Foundation Contractors (EFFC), DFI, member organizations and Carbone 4, a consultant with ex- perience in life cycle assessment. The tool was born out of the fact that governments and clients were asking for embodied carbon information for foundation systems, and that in- dividual companies were building their own calculators to meet these requests. To help all member organ- izations achieve compliance, and to have a sector-specific tool that is certified to the prevailing standards, EFFC and DFI agreed to partner to create the carbon calculator, which is: Excel based and, therefore, easy to learn and use Updated on a regular schedule Certified to ISO 14067, GHG Protocol and PAS 2050 Free and available for anyone to use Even though this tool is free and easy to use, most projects in the industry do not have a carbon calculation performed. The case to use the calculator is more obvious for members in places like Europe where there are stricter reporting standards and government work can be driven by sustainability over cost. In North America this is not the case, yet. Without directives from clients and governments, what can compel the industry to start regularly using this tool and care about the carbon emissions of projects during design and construction?

Nov 1, 2022

By Manish Kumar

One of the recent advances in the field of testing of concrete piles is the Non-Destructive testing (NDT) of piles. This paper deals with a specific project where this technique was employed along with an extensive program of conventional testing methods to cross check the results. Conventional testing of the Bored, cast-in-situ piles involved taking full length concrete cores from piles to check physical properties such as core recovery, RQD, crushing strength and density of concrete. Additionally, a number of questionable piles were exposed and inspected and actual load tests were performed on selected piles. Concrete pour cards were used to compare actual Vs theoretical consumption of concrete. A direct comparison of the conclusions drawn from both these testing methods provided an excellent opportunity to better understand the intricacies of NDT technique. The study undertaken clearly indicated a need for developing clear guidelines and specifications for the use of this method of non-destructive testing of piles before the .method can be accepted as a useful quality control tool at the construction sites.

Jan 1, 1996

By Masaaki Terashi

The machine for the hybrid method called JACSMAN is ordinarily a dual shaft machine. Each shaft has augers at three different levels and nozzles for jetting at two different levels. The distance between two shafts may be changed according to the particular requirements. Figure 4 shows single shaft and a treated soil column created by the method. The diameter of the auger is 1.0 m. As the jetting nozzles locate at the periphery of the auger, jetting can achieve the additional treated soil column beyond the diameter of the auger. The diameter of the jetting improvement is fixed at 2.3 m.

Feb 10, 2003

By H. R. Shen

Cushion materials are one of the most important links in an efficient piling system. In the past, little has been done in China on this problem, so engineers are still used to those traditional woods, papers and coir ropes. In this paper, the SOA of piling cushions, their testing method and parameters used in wave equation analysis for piling are briefly reviewed. The static and dynamic mechanical characteristics of 3 types of cushion material have been determined in laboratory and suggestions about testing method and evaluation of test results are given.

Jan 1, 2010

By Richard Schmidt, Lijun Deng, Mohamed Abdelaziz, Weidong Li

Helical piles are widely used as a foundation supporting a variety of different structures. Understanding the axial behaviour of helical piles is required to confirm the engineering design. Helical pile research is often conducted in the field, but this method can be prohibitively expensive in some cases. Geotechnical centrifuge modeling offers an alternative method for the helical pile research and practice. A series of axial load tests of helical piles installed into cohesive soils were conducted on the geotechnical centrifuge at the University of Alberta. The objective was to investigate the effects of inter-helix spacing and soil strength on the axial behaviour of helical piles. Four types of aluminum model helical piles including one single-helix pile and three double-helix piles with various inter-helix spacing ratios were tested. Both compressive and tensile loading tests were conducted. All model piles were instrumented with multiple strain gauge stations. The clay had an undrained shear strength of approximately 50 kPa and 120 kPa. The test results indicate that there is a transitional failure mode between the two widely recognized failure modes, i.e., individual plate bearing and cylindrical shearing. The shaft adhesion was significantly reduced by the helix. Axial capacities were comparable to the field test results.

By Emad Farouz, Roger Failmezger

"The proposed reconstruction of I-75 downtown consists of widening an approximately 2.46 Km section of IR-75 through the northern section of downtown Dayton, OH, USA. Bridge B-13 is a 9-span continuos prestressed concrete I-beam, 319.0-meter (1,048-foot) long bridge with a stub abutment on MSE walls for the rear abutment, and a stub abutment with spill-through slopes for the forward abutment. The piers in the river were located parallel to the Great Miami River, and are full-height reinforced concrete wallsPRESSUREMETER TEST PROCEDUREThe driller advanced either casing or augers approximately 1 meter above the pressuremeter test. Steel casing was used to advance borings performed in the river, and augers were used for borings on land. Mud rotary drilling with a large diameter roller bit was used to remove all of the gravel and cobble fragments inside the casing or augers.At the pressuremeter test elevation the driller used a 63.5-mm (2.5-inch) carbide button bi-cone bit, using a rotation rate of about 60 rpm, a mud fl ow rate of about 10 gallons per minute (40 liters per minute), and an advance rate of 6 to 10 minutes per meter (2 to 3 minutes per foot). To minimize vibrations, advance rates were slower where excessive cobbles were encountered. The 63.5-mm (2.5-inch) O.D. slotted casing pressuremeter was lowered to the test elevation, often requiring either pushing or hammering into the test zone. We believe that the test zone was not perfectly straight, or that gravel or cobble fragments jutted into the test zone and had to be displaced to advance the pressuremeter into the test zone. The slotted casing prevented membrane damage during insertion. A photograph of the slotted casing being lowered into the borehole is shown below.The pressuremeter was calibrated for system compressibility and membrane resistance. At full expansion of 800 cm3, the membrane resistance of the slotted casing was about 2.5 bars.Strain-controlled tests were performed using a Texam control unit with a monocell probe. Volume increments of 20 cm3 were injected into the probe and corresponding pressures were measured. Near the end of the elastic portion of the test, an unload-reload cycle was done. A creep test was performed for 10 minutes at the next volume increment. The test continued until either 800 cm3 were injected or the membrane burst."

Jan 1, 2007

By H. (Sam) Salem

A site investigation for a wide and tall hotel building, in the San Juan Bay area, Puerto Rico, indicated a soil profile of silty clay on sand, soft and loose enough to require piled foundations. The apparent uniformity of the soil profile across the site indicated that a single pile driving and termination criterion could be applied to the installation of the piles ? driven precast concrete piles. Because of the size of the site and importance of the project, the project also included a static and dynamic testing programme. The dynamic monitoring using the Pile Driving Analyzer (PDA) verified a consistent hammer operation. However, the results of the static loading tests showed significant and inconsistent variation in pile capacity between locations and little correlation between end-of-driving and restrike penetration resistances (blow-counts) and pile capacity. Therefore, it was not possible to rely on a simple depth and blow-count termination criterion for the site. In contrast, pile driving response in terms of measured reflected force and mobilized resistance coupled with CAPWAP analysis gave a reliable correlation to the results of the static loading tests. As presented in the paper, the dynamic testing programme was enlarged and used to develop and verify a complex set of termination criteria tailored for the multitude of conditions encountered across the site to achieve and ensure economical and safe pile installation.

Jan 1, 2008

By Michael W. Neill, O&apos

The performance of foundations that combine the high bearing capacity of rafts (mats) with the settlement reduction capability of piles is described through a summary of 24 case histories. Structures included are high-rise commercial office buildings, governmental buildings, industrial facilities and residential buildings, and subsurface conditions range from soft clay to stiff soil overlying rock. Pile types are bored, augered and driven. Since piled rafts are not commonly used in the United States, most of the case histories are from overseas. In all cases the performance of the foundations was monitored during and after construction. Particular emphasis is placed on measured settlements of the piled-raft foundations, distribution of resistance between piles and raft, and general analysis methods that were used by the designers for various geotechnical circumstances. Finally, patterns of behavior are summarized. In most cases, the piles were not designed to mobilize their full capacities under sustained loading of the foundation; therefore, under long-term loading conditions, the piles typically carried more load than the raft. This paper is the result of a study conducted by ITC-18 (Deep Foundations, Willem Van Impe, Chair) of the International Society for Soil Mechanics and Geotechnical Engineering by a subcommittee chaired by the author.

Jan 1, 2003

By Paul W. Mayne

The axial load-displacement-capacity and load-transfer response of deep foundations can be conveniently assessed by geophysical piezocone tests that provide four independent readings with depth, including tip stress (qt), sleeve friction (fs), porewater pressures (ub), and shear wave velocity (Vs). The penetration data (qt, fs, and ub) of the CPT are utilized to obtain the pile side friction (fp) and end bearing capacity (qb) while the shear wave measurements provide the initial stiffness. Within an elastic continuum framework, the axial pile deflections are calculated and an approximate nonlinear response is obtained by modulus degradation from small-strain response (G0) to intermediate- and large-strains (G). The continuum solution permits separation of load transfer along the sides and proportion to the base. Applications are shown for case studies involving an end-bearing drilled shaft, two friction-type drilled shafts in Alabama and Georgia, and a "Class A" prediction involving driven pipe piles in residuum of the Atlantic Piedmont geology. Load-transfer data were available for the drilled shaft foundations.

Jan 1, 2002

By P. Srinivasulu

The popular theoretical models used for assessing the dynamic behaviour of piles under vertical and lateral excitations are critically reviewed. An experimental study is presented on model piles with varying slenderness ratios. The theoretically evaluated and experimentally deduced natural frequencies and resonant amplitudes of the test pile-soil system are compared. The dynamic stiffness and damping are seen to increase with increasing slenderness of piles. Further, the damping yielded by the theory is found to be on the unconservative side.

Jan 1, 1996

By R. K. M. Bhandari

Geotechnical investigation for a LPG plant located in Assam state - an area of high seisimicty - revealed a layer of loose to medium silty sand susceptible to liquefaction at some depth below the finished ground surface. Liquefaction analyses were carried out using simplified Seed's approach as well as considering the progressive buildup of pore pressures with cyclic earthquake loading. Seismic settlements were computed for areas where the analysis indicated partial liquefaction. Pile foundations in areas where complete liquefaction was indicated, were treated with gravel drains to prevent buildup of pore pressures. The paper presents and discusses the liquefaction analyses, effect of non-liquefiable overburden soil on the liquefaction potential of the silty sand and the remedial measures that have been taken to ensure safety of the pile foundations in transmitting vertical and lateral loads.

Jan 1, 1996