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By Brian Littlechild

Whilst there is much innovative work being undertaken in South East Asia in the space allowed in this paper we have settled on describing in more detail the work that has been done with shaft grouting of deep foundations and piles founded in rock both in end bearing and socket friction. The paper is necessarily in two parts. The first part is about the application of shaft grouting since its introduction to the region some eight years ago. It describes, for the first time, much of the detail of the different techniques used and the construction and the design benefits achieved with shaft grouting in five countries in the region. The second part outlines the enhancements achieved in the design of piles founded in rock and brings together the results of 10 years of test loading. This includes the load testing of 1.2m to 1.5m diameter piles to a maximum of 30MN on granite and a recent programme of tests on a wide range of strong rock types in Hong Kong. The ground conditions for these deep foundations vary widely, from sedimentary soils to in situ weathered granite and meta-sedimentary rocks. The construction techniques include barrettes constructed using mill techniques and bored piles formed under bentonite and water using both oscillators and rotators.

Jan 1, 2000

By J. H. Qian

China is one of the countries with comparatively wide distribution of soft soil. In the wake of the rapid developement in the national economy and construction, the improvement technique of soft soil foundation has been perfected gradually. At the present, an integrated system of soft soil improvement has formed, features of such a system are shown by the variety of improvement methods, the complement of theoretical study to project practice. This paper summarizes mainly the following methods: lime column, vertical drain, vibroflotation and dynamic consolidation.

Jan 1, 2010

By Juhyung Lee

Recently, large diameter drilled shafts are often used for foundations of large-scale marine bridges with high capacity and required to resist lateral loads. Steel casings are essential in supporting the hole-diving concrete installation of the drill shafts constructed in the sea. The casings, however, are usually not considered as the structural elements and their load bearing capacity is often overlooked in the design of drilled shafts. As the diameter of drilled shafts becomes larger, there are higher demands for more efficient and economical design of large-scaled drill shafts in the sea. Steel-concrete composite columns are popular for the superstructure of bridges, and the outer steel attached to the shaft increases the shaft resistance through confining the concrete. In this study, the lateral resistance of steel-concrete composite drilled shafts was evaluated quantitatively based on the numerical analysis. When steel casings are used as structural elements such as the composite columns. Ultimate lateral bearing capacity of composite drilled shafts with various diameters was numerically calculated through the 3D finite element analysis. For that, elasto-plastic model with the perfect plasticity is involved to capture the ultimate load. A commercial FEA program, MIDAS-GTS, is used in this study. Real field conditions of the west coast, Korea were examined to set up the ground conditions and pile lengths required for this parametric studies. Detailed characteristics of the stress and displacement distributions are evaluated for the better understanding on the mechanisms of the composite shaft behavior.

Jan 1, 2008

By Z. Q. Bian

The wireline sampling originates from core drilling in rocks. The authors combined the wireline sampling technique with conventional undisturbed soil samplers, including Osterberg sampler, Denison sampler and double tube barrel, and then developed the wireline samplers of WPS, WSS and WSR models. These samplers are able to sample various soils. They reserve all the advantages of the original samplers, and moreover, they are noted with quick hoisting and lowering by wire rope. Therefore, it becomes an efficient new technique of sampling undisturbed soil from deep foundation.

Jan 1, 2010

By Saba Mohan

This study presents results based on the Pile Installation Demonstration Project (PIDP) that was conducted as a part of the East Span San Francisco-Oakland Bay Bridge Seismic Safety Project. For the three full-scale pile installations, two different high-energy hydraulic hammers were selected for the installation. However, these hammers may not have sufficient energy to drive these large diameter piles at their ultimate capacity following long-term set-up. Nevertheless, these hammers were selected because, soil plug behavior, the generation of excess pore pressures and remolding of soil during driving were expected to reduce the shaft and end bearing resistance, and therefore reduce the energy required to drive these piles to design penetration. Data collected during continuous installation driving and after a series of re-strikes at different set-up times ranging from 1 to 33 days were used as input data for CAPWAP. These results were used to estimate the soil resistance along the pile length and at the toe of the pile, and the soil pile set-up behavior. Validity of the procedures used to predict the soil resistance to driving and predicted blow counts were verified with the field observed blow counts and the energy that was delivered to the pile. Based on combined CAPWAP analyses, the soil pile set-up with time was estimated and compared with results of other methods currently available in the literature for predicting the soil pile set-up rate.

Jan 1, 2002

By Robert J. Carle

This paper reviews a variety of highway structures which have been built using steel sheet piling as the permanent structural elements of bridge piers, abutments and wingwalls. Those structures built over the past 20 years in Europe include major highway bridges over railroads, highways and waterways in both urban and rural locations. Most highway structures built in the United States using steel sheet piling have been limited to secondary roads in rural locations. The main thrust of this paper is the presentation of various design concepts for highway structures which utilize steel sheet piling. The main purpose is to challenge the profession to move forward from this conceptual presentation and to develop the details necessary to provide safe, cost-effective structures which go well beyond the scope of those being built in the United States today.

Jan 1, 1989

By David R. Black

Foundation problems due to collapsible and expansive soils are well known throughout the arid western United States. Millions of dollars are spent annually to counteract the effects of such soils for both new foundations and existing foundations suffering from settlement or heave. Over the last 20 years helical screw piles have come into wide-spread use as a permanent deep foundation element for these problem soils, especially in the arid western United States where, in some areas, they are a standard of practice. Independent research resulting in recognition by every national building code in the United States has legitimized helical screw pile technology. Once thought of in terms of light structural underpinning, helical screw piles of today are designed to take heavy structural loads, vertical and lateral, tension or compression, including seismic loads. With proper pile grouping, design capacities for column loads over 4,500 kN (1,000 kips) are attainable. This paper discusses design considerations specifically dealing with collapsible and expansive soils: soil investigation parameters, predicted settlement and long-term creep, heave in expansive soils, downdrag in collapsible soils, shaft slenderness buckling, maintaining shaft alignment during installation, refusal condition, water migration along the shaft, lateral loading, cyclical loading for seismic loads and machine foundations, corrosion, helix durability during installation, the installation torque vs. capacity equation, and design methodology. The paper concludes with several case histories where helical screw piles were used for new structural foundations and to underpin existing failed foundations in St. George, Utah, Cedar City, Utah, and Denver, Colorado, USA, sites of some of the most expansive clay and collapsible soil in North America. Soil descriptions and performance histories are presented.

Jan 1, 2002

By K. K. S. Ho

In Hong Kong the design of excavated piles in weathered granite has conventionally been based on a rule-of-thumb which relates the allowable base bearing capacity to the SPT N value, with no allowance for skin friction. This rule-of-thumb has been shown to generally lead to conservative designs. To improve the overall understanding of load-transfer mechanism of excavated piles in weathered granite, instrumented pile load tests have been conducted. This paper summarises a selection of instrumented pile load test data in Hong Kong and the observations made of the results, which indicate that there was considerable scatter in the back-calculated skin friction values. However, the mobilized skin friction was shown to be significant which can lead to substantial savings in design.

Jan 1, 1996

By Les R. Chernauskas

? What is Integrity Testing? ? Cross-Hole Sonic Logging (CSL) ? Single-Hole Sonic Logging (SSL) ? Typical Specifications ? Case Histories ? Observations and Conclusions WHAT IS INTEGRITY TESTING? General Definition ? Process in which the condition or structural makeup of an object can be evaluated with respect to defects such as a reduction in cross section (void or crack) or reduction in material strength (water, slurry, soil mixed with concrete). ? If the defect is severe enough, it can reduce or alter the load carrying ability of the object.

Jan 1, 2001

By G. W. Plant

This paper describes the design philosophy and construction details of piles between 25m and 32m deep to support 160m high and 110m base diameter cooling rowers for a major power station. It is sited on deep expansive soil where a vast plantation of Eucalypts had been felled. The depressed water table is expected to rise, leading to swell of the soil and uplift forces on the piles. These forces, combined with the complex loading from the cooling towers, led to design tensile loads up to 20MN (2 000 tons) per pile. When competent stable material was present hand excavated underreams 3m in diameter were constructed for the piles sup-porting the shells. However, in some areas it was not possible to form an effective underream and an innovative solution was sought. This comprised unstressed dowels in the underlying sandstone which were formed by percussion drilling through void formers cast into the piles.

Jan 1, 2010

By Andrew Baxter

The Crystal Bridges Museum of American Art in Bentonville, Arkansas is a beautiful glass and concrete structure cut into a valley that mingles with water ponds spanned by multiple bridges with suspended roofs. Or, at least it will be when completed in 2009. At Crystal Bridges, most of the proposed buildings involve cuts up to 50 ft high to be retained by the building structures. This requires the construction of retaining walls adequately founded to support lateral loads of up to 70 kip/ft. To add to this difficulty, the site is within a karst region with all the variability and irregularities associated with solutioning and erosion of the parent rock in this environment. The irregular rock profile made it virtually impossible to conceive a predictable arrangement of shallow footings and shear keys for the retaining walls. The existence of layers of soft soils within a hard rock formation made a caisson foundation impractical. The authors developed an innovative solution based on micropiles, which proved to be invaluable from a cost and schedule point of view. In areas where rock was shallow, micropiles were used as ?shear pins? to transfer the horizontal loads to the rock. In areas with significant overburden, a system of vertical and battered micropiles was devised to carry vertical and horizontal loads from the retaining walls. This paper presents a detailed description of the design and installation of the micropiles used as shear pins, and includes the results of lateral load tests performed on full-scale models of the grade beams on shear pins. The work performed shows that micropiles in rock can be effectively utilized for support of significant lateral loads provided that an adequate arrangement of suitably sized micropiles is provided, and that micropiles used as shear pins may develop significant tensile stresses when loaded laterally.

Jan 1, 2008

By James M. Tantalla, Roderic A. Ellman, W. Allen Marr, Scott R. Bamford

"Construction of the powerhouse for the Willow Island Hydroelectric Project required a 100-ft deep excavation inside the limits of a cofferdam and embankment-seepage cut-off wall through soil and rock adjacent to the Ohio River. Portions of the rock had preexisting weak plans and slickensided surfaces with low frictional strength. Stability analyses were performed for critical sections of the excavation to evaluate the stability of the soil slopes and rock cuts using buckling, tension crack, and limit equilibrium analysis techniques. Loading conditions included the 100-yr and intermediate floods, normal pool, sudden drawdown, and seismic design conditions.Stability analyses indicated adequate factors of safety for soil slopes and for rock cuts through the landside embankment sections. However, the results of deep-seated stability analyses through the rock supporting the riverside cellular cofferdam indicated unacceptable factors of safety. Consequently, the riverside portion of the excavation required measures to increase stability. Long, high-capacity rock anchors and deep dewatering wells to lower the site piezometric head were chosen for this purpose.Thirty high-capacity rock anchors were installed on the upstream, riverside, and downstream sides of the cofferdam rock cut. Required rock anchor loads varied from 1,968 to 2,074 kips. The designed anchors consisted of multiple, seven–wire strands with up to 59 strands per anchor. Bond lengths used an allowable bond stress of 100 psi based on the rock bond measured with pull-out tests. Maximum bond and anchor lengths were 50 ft and 140 ft, respectively. Measurements of forces in selected strands and displacements of the excavation showed excellent performance."

Jan 1, 2017

By Issa S. Oweis

Two Towers are currently under construction in Central Moscow in the Russian Federation. Building A is a 96 story tower and Building B is a 65 story tower. The columns in both structures bear on a thick concrete mat that is supported on drilled shafts, 1.5 m in diameter. The shafts derive their capacity from weak limestone with layers of marl. Assigned allowable shaft loads were initially based on rock strengths that were later verified by load tests using the Osterberg Cell. One of the load tests was carried to near failure which allowed refining socket friction values that were later used in the design of Building A. All shafts were advanced using an auger and concrete placed in the dry. Grout tubes were placed with the reinforcing cage which allowed grouting of the limestone in contact with the shaft. Load sharing between the shafts and the mat was approximated using published methods as well as site specific finite element analysis. This paper covers the methodology of design, analysis of the Osterberg results to derive non-linear stiffness of the rock and differences between finite element analyses and results by approximate methods.

Jan 1, 2007

By Martina Balic

Dynamic properties of the drilled shaft foundations supporting Doremus Avenue Bridge were determined by forced vibration testing. The main objectives of the substructure testing at Doremus Avenue Bridge were: (1) site evaluation with respect to the dynamic soil properties, and, (2) shaft evaluation for the purpose of definition of their dynamic stiffness. The site characterization entailed crosshole testing for the purpose of evaluation of the shear modulus profile. The drilled shaft impedance evaluation was done through forced excitation using an electromagnetic shaker. The responses of the tested shaft, as well as the response of adjacent shafts, were measured for the purpose of evaluation of the shaft interaction. To gain a better insight into the shaft dynamics, one of the shafts was instrumented with five triaxial geophones distributed along the full length of the shaft. The scope and results of the site characterization, shaft impedance and shaft interaction evaluation are presented.

Jan 1, 2004

By Maurice Guillaud

The most striking innovations on diaphragm-wall construction plant are those associated with continuous real-time trajectory monitoring of the excavating tool (either a grab or a hydro-cutter). The recent equipments are fitted with clinometers and gyrometers to control deflection, rotation or deviation from the vertical, thus allowing to install diaphragm-walls with a verticality accuracy of less than 0.3%. One of the greatest advantages of extensive use of on-board IT systems on the Hydrocutters and hydraulic grab machines is that it aids quality control by automatically producing complete real-time reports of all excavating data (verticality, depth, type of ground, rate of progress, stoppages, etc.). These reports are available to the Engineer, providing the total transparency required for Works Supervision and the Quality Assurance Plan. They also provide the Contractor with input data for databases used for optimising efficiency and progress criteria on future jobs.

Jan 1, 2002

By F. M. Abdrabbo

Flight auger bored piles are formed by screwing a continuous flight auger into the ground, and pumping cement/sand grout or concrete down the hollow stem of the auger as its withdrawn. The auger is driven at the top by hydraulic or electrical motor and is guided by a vertical crane leader. Loading tests on concrete piles are described. The stability plot method is used to drive the shaft friction and the end bearing load components of the pile capacity. This paper outlines features of crucial construction factors that affect the geotechnical capacity of this type of piles. These factors include, vertical speed of auger during boring, grout factor, grout pressure, number of reborings, type of material, and slump of concrete used to form the piles. Two of these factors are highlighted in this paper. It was found that, shaft resistance is independent of grout factor, whilst point resistance increases as grout factor increases. Nevertheless the engineer should decide the safe pile load associated with the most economical grout factor. High vertical speed of auger during boring of piles may cause disaster for the adjacent buildings, due to soil decompression.

Jan 1, 1993

By Beim Jorge, Piscsalko George

"Verifying the quality of cast-in-place foundation applications, particularly those cast under slurry, is of course important, due to its great dependency on the methodology employed and on the practices of the site personnel. Due to the techniques used to install these elements, it is usually not possible to inspect the hole prior to grout or concrete placement, but there are several Non Destructive Test (NDT) methods available to assess the integrity of the completed foundation elements. This paper will compare several NDT methods with the Thermal Integrity Profiling (TIP) method for verifying the integrity in Continuous Flight Auger (CFA) piles and Bored Piles. The Thermal Integrity Profiling method will be described and some examples will be presented where TIP testing was used to confirm the structural integrity of CFA piles and Bored Piles.IntroductionThere are several Non Destructive Test (NDT) methods available for integrity testing of foundation elements. Each of those methods has advantages and disadvantages (White et al, 2008). Some methods test the integrity based on the reflections of a stress-wave generated by low or high-strain impact, while others require tubes to be installed prior to concrete pouring, and test the integrity between those tubes, or within a small proximity of them. The former methods (especially the low-strain) are faster and more cost-effective, but are not able to detect the quadrant where the damage is located. The latter methods are able to determine the quadrant, but do not test the region outside of the reinforcing cage, that is, they are not able to determine the concrete cover. The Thermal Integrity Profiling (TIP) NDT method overcomes the limitations of these other NDT methods.Overview of Shaft Integrity MethodsUntil now, the most widely used methods to test the integrity of Bored and CFA piles were the low-strain pile integrity testing and the cross-hole ultra-sonic testing. The low-strain method for integrity testing (PIT) involves attaching an accelerometer usually to the pile top (using a putty or wax) and striking the pile surface with a handheld hammer, which causes a compressive wave to enter the pile. This wave is totally reflected when it reaches the end of the pile or a major defect, and is partially reflected when it encounters any change in crosssection, or a change in the resistance or density of the pile material. These reflections arrive at the top at a time determined by the distance and wave speed, and causes a noticeable change in the signal detected by the accelerometer. The acceleration signal is normally converted to velocity by simple integration, and sometimes the force applied by the hammer is also measured. The velocity (and force) signals can be processed by the pulse-echo method (in the time domain) or by the transient response method (in the frequency domain)."

Jan 1, 2015

By G. L. Sivakumar Babu, P. Chaithra

"Raft foundations which are used against differential settlements and for carrying heavy loads can still be subjected to excessive settlements even if it is safe against bearing capacity consideration. Providing additional piles under the raft can reduce such settlements to acceptable values. In addition to settlements, the piles also relieve the raft a part of the total load and thus the bearing capacity of the Combined piled raft foundation (CPRF) is improved. Parametric study of response of piled raft foundation has been conducted and the results have been presented. The study is conducted using finite element based software, PLAXIS 2D. The main objective of the paper is to evaluate the parameters that affect the performance of piled raft for an economical and effective design. It has been shown that piled rafts are an economical solution in foundation design compared to raft foundation, for the soil conditions considered in the paper.1. INTRODUCTIONThe aim during the design and construction process of high-rise building foundations in urban areas is to ensure the lifelong safety and serviceability of the new and existing buildings in the neighborhood. In order to realize this aim in a cost-optimized manner, the combined pile raft foundation (CPRF) was developed (Katzenbach et al., 2005). For the foundation of high rise buildings with good subsoil, the simplest structure considered is a raft. But when the subsoil near the ground surface has low load-bearing capacity, high-rise structures are often rested on piled foundations.A piled raft and pile group serves similar purposes, but there are essential differences between them. A pile group is a set of piles that have a pile cap. The piles would be designed to share the pile load at ultimate state. The pile cap would be designed to link the piles together but the contribution of the pile cap to bearing capacity will not be included in the design. On the other hand, a piled raft is a foundation, wherein piles are provided along with the raft so that the total load acting is shared partly by the raft and partly by piles, rather than being dominated by the piles (as in a pile group). Piled raft foundations utilize pile support for control of settlements with piles providing most of the stiffness at serviceability loads, and the raft element providing additional capacity at ultimate loading (Poulos, et al., 2011). Therefore, piles are included in a foundation for two main design purposes: to provide adequate bearing capacity and to bring down the settlements to an acceptable level."

Jan 1, 2015

By Theodore W. Vogelpohl

Augered cast-in-place piles have proven to be effective, adaptable and economical for projects throughout the Ohio River Valley. Specifically, they have been used extensively for high-rise structures, sports stadia and large commercial developments along the Cincinnati, Ohio and Northern Kentucky Riverfront. They have been designed and utilized as relatively short toe resistance piles in bedrock, and intermediate to long toe and shaft resistance piles in granular outwash deposits above the bedrock. They have been designed for large axial compression loads as well as moderate axial tension loads and lateral loads. This paper presents a few load test results that demonstrate the range of capabilities of augered cast-in-place piles in the variable subsurface profile along the Cincinnati, Ohio/Northern Kentucky Riverfront.

Jan 1, 2005

By Barry C. Roth

Driving of large piles in water can impact marine wildlife. Bubble curtains can mitigate these adverse effects. The procedures for and preliminary results of monitoring airborne, waterborne and groundborne vibrations with and without bubble curtains on a test project involving 2.438 m piles to 110 m is reported here. We observed fish kills and sea lions apparently fleeing the area. These phenomena were presumably due to the extreme acoustic effects of the powerful hammers which generated waterborne sound intensities locally in excess of 240 dB. This waterborne pile driving noise data collection undertaking is believed to be the most extensive ever attempted.

Jan 1, 2001