Search Documents

By Murad Y. Abu-Farsakh, Md Habibur Rahman

The properties of all natural soil deposits are highly variable, and they are rarely homogeneous. Cone penetration tests (CPT) were used to assess the site variability, which was then incorporated into the Load and Resistance Factor Design (LRFD) of pile foundations. Data from six project sites with multiple CPT tests conducted at various locations were collected for this research. The semi-variogram was used to assess the spatial variability of CPT data (corrected tip resistance, qt) for each location. For each location, the coefficient of variation due to spatial variability (COVR,spatial) was calculated. From COVR,spatial and COVR,method, the total coefficient of variation (COVR,total) for each site was calculated, which was then used to calibrate the resistance factors (ϕspatial, ϕtotal) for use in LRFD pile foundation design. The findings of this study demonstrated the importance of using site variability in LRFD pile design. For sites with lower site variability than the design method (i.e., COVR, spatial < COVR, method), the value of the COVR, total will be decreased, and hence the resistance factors (ϕspatial or ϕtotal) will be increased (credit), and vice versa.

Sep 8, 2021

By Y. W. Mou

In order to improve the construction of pile foundations and deep foundations of largo sizes, the paper deals with the method of installing square or rectangular bored-piles for annular foundation as well as large-sized hollow or solid foundation.

Jan 1, 2010

By D. A. Ponniah

The installation of a pile is considered analogous to the expansion of a cylindrical cavity of a diameter equal to that of the pile. Using Vesic&apos;s theory of the expansion of cavities the effect of soil properties on pile installation loads, radial pore and total pressures are evaluated. The theoretical results are compared with load and pressure measurements made in field trials in a stiff clayey glacial till in the U.K.

Jan 1, 1987

By L. J. Whitworth

Five trial piles were constructed during the trial pile programme for the Birmingham International Convention Centre. In addition, trial piles have been tested on two other sites in central Birmingham. Methods of pile construction were conventional sandstone rock sockets, sleeved piles and voided piles. The results of these load tests are compared with the theoretical predicted behaviour based on the results of unconfined compressive tests of rock core taken on the Convention Centre site and on other sites in the central Birmingham area. On the basis of this work, the various design procedures are discussed.

Jan 1, 1989

Caissons hand dug to a depth of about 100 feet were used to underpin three important structures at an industrial site in the State of Utah. The caisson shafts extended through 30 to 40 feet of coarse, granular soils and 25 to 60 feet of sands and clays to bear on a very dense, coarse gravel and cobble stratum near the water table. The shafts were belled to 12 feet square at their bearing elevation. Bearing pressures of 20 ksf were assigned. The shafts were lagged with timber. The use of hand-dug caissons allowed continuous operation of the facility during underpinning. Settlements after underpinning have been minor and well within the estimated magnitudes. Instrumentation was placed in two of the caissons with varying degrees of success.

Jan 1, 2010

By F. Keith Jacobson

To be involved in the construction of a deep dredged caisson for a major bridge pier is one of the most rewarding and professionally challenging experiences one can have in the bridge construction business. That experience was doubled in the construction of the two deep dredged caissons for the Highway 82 Bridge over the Mississippi River near Greenville, Mississippi. The challenges and the construction risks associated with constructing these two dredged caisson pier foundations highlight the construction engineering innovation associated with major bridge pier construction. The 1,378-foot Main Span of the Highway 82 Bridge makes it the longest cable stayed bridge span over the inland rivers of the United States. The main piers for this bridge are supported on two dredged caissons measuring 80-feet by 122-feet in plan, founding 200-feet and 170-feet below the river surface. The challenges of constructing these caisson structures, sinking them through 70-feet of water to the river bottom and then excavating and further sinking them to the founding grade without exceeding the design tolerances, were enormous. The construction engineering opportunities for innovation included major breakwater structures to create a friendly environment in 11 fUsec currents, the first time use of Articulated Concrete Mattresses for river bottom scour control, unique air dome design to maximize the buoyancy of the caisson structure while floating, a caisson guide system to assure positive control and positioning of the caisson during the initial sinking phases. and a comprehensive sinking plan to assure maximum control and minimum risk. Many of the innovative solutions to the construction challenges on this bridge will be incorporated into future caisson construction projects on the lower Mississippi River.

May 11, 2007

By Jesús E. Gómez

A recent bridge underpinning project provided a unique opportunity to obtain information on the load-deflection response of 260 hollow-core bar micropiles. All production micropiles were proof-tested to a maximum load of 125 percent of the design load. In addition, four verification tests were performed on sacrificial micropiles to at least two and a half times the design loads. This paper presents the results of the verification and proof tests performed for this project, and provides recommended values for design of hollow core bar micropiles in soils similar to those encountered. This work shows that hollow core bar micropiles provide a significant unit bond capacity in both granular and fine soils, which may be greater than that typically expected in pressure-grouted (Type B) micropiles. The hollow core bar system allows faster installation rates in the soil types encountered than other traditional micropile techniques, and can be installed with relatively simple quality control procedures.

Jan 1, 2007

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 Masaki Kitazume

Five papers were presented orally to the topics of Jet Grouting and Deep Mixing. The session was started with a brief introduction by the moderators. Following the oral presentation, floor discussions were directed by the moderators. A brief introduction of each of the oral presentations is provided before each discussion.

Feb 10, 2003

By Glenn J. Rix, Eduardo Tavera, Raphael Siebenmann, Zhongjie Zhang, Robert C. Bachus, Jongwon Jung

"The Louisiana Department of Transportation and Development (LADOTD) uses a variation of the FHWA-modified Gates equation to verify the nominal pile bearing resistance, typically on smaller projects where static load tests and dynamic monitoring are not practical. An inconsistency in the resistance factors for load and resistance factor design (LRFD) penalizes the target pile capacity needed during field observation if the LADOTD dynamic formula equation is used, which is unreasonable, and has created confusion among designers, consultants, district personnel, and inspectors in Louisiana. The objectives of this project are to recalibrate the FHWA-modified Gates equation and update the associated LRFD resistance factor for pile types and local soil conditions encountered in Louisiana. Improved consistency relative to the current design approaches will be achieved if the updated resistance factor matches or exceeds the worst-case resistance factor used by LADOTD, which will reduce confusion among users. Updating the resistance factor will also serve to increase confidence in the FHWA modified Gates equation, optimize the efficiency of the piles, and reduce project costs.IntroductionThe original 1957 Gates pile driving formula (Gates, 1957) is an empirically derived dynamic formula that is used to predict pile capacity in the field during pile installation. The original Gates formula tends to over-predict pile capacity for low driving resistances and under-predict pile capacity for high driving resistances (Hannigan et al., 1998). Thus, the Federal Highway Administration (FHWA) proposed a modified version of the Gates formula that addressed this limitation. The FHWA–modified Gates equation is:"

Jan 1, 2017

By George Piscsalko

"Quality control of drilled shafts and ACIP piles is greatly dependent upon the practices of the site personnel. In many applications it is difficult to properly inspect the shaft prior to concreting, such as when the shaft is drilled under slurry. In other cases, such as ACIP piles, it is impossible to inspect the shaft in any manner prior to concreting. There are numerous methods currently available to assess the integrity of drilled shafts and ACIP piles. Each method has its advantages and limitations. This paper will compare the various available methods as well as introduce a new method for assessing integrity in drilled shafts and ACIP piles. This new method, known as Thermal Integrity Profiling, determines the integrity over 100% of the shaft both inside and outside the reinforcing cage by measuring the hydration temperature of the concrete along the length of the shaft. These temperature measurements can be made by either passing a thermal probe through a standard Cross Hole access tube typically 12 to 48 hours after concrete placement, or from embedding thermal wires within the shaft prior to concrete placement and monitoring them with unattended data collectors for 12 to 48 hours after concrete placement. This Thermal Integrity Profile method will be described in detail and several case histories will be presented. Additional testing methods which will be compared include low strain Pile Integrity Testing, and Cross Hole Sonic Logging. Advantages and limitations for each method will be discussed.IntroductionDrilled shafts and Augered Cast-in-Place (ACIP) piles have been increasingly used over the past several years due to several reasons including the reduced noise and vibration, speed of installation for ACIP piles, and the large axial and lateral capacities which are attainable for very large drilled shafts. ACIP piles are drilled and cast without any visual inspection. Drilled shafts can be cast in a dry hole which allows for inspection of the hole prior to casting, but the casting process is very difficult to nearly impossible to inspect with any accuracy. Drilled shafts are frequently cast under slurry as a means to stabilize the surrounding soils during the construction process. When casting a drilled shaft under slurry, it is very difficult to accurately inspect the hole prior to casting and it is equally difficult to inspect the shaft during the casting process. Many of the above mentioned processes are blind to inspection and therefore the chances increase for having defects present in the completed elements."

Jan 1, 2017

By Peter Deming

"PART 1 OF 2INTRODUCTIONSlurry trenches are the least cost hydraulic barrier available, if the excavated spoils can be recycled into backfill. As such, slurry trenches are constructed where possible, sometimes at high risk. Slurry trenches are also used to install biopolymer drainage trenches, which have a low safety factor because the biopolymer slurry weight is marginally greater than the weight of water. In marginal ground the construction risk falls to both the Owner who designs and asks for the construction, and the Contractor who manages the work and promises to complete the project successfully. This paper discusses design and construction of slurry trench barriers in marginally stable ground and where groundwater chemistry invokes the need for slurry management details to obtain proper backfill placement.As a designer, Mueser Rutledge Consulting Engineers works for both Owners and Contractors. We are usually able to convince Owners of their responsibility for design detailing in order to obtain a working final product and to obtain reasonable bids from Contractors by disclosing construction needs and designing to reduce the contractor’s exposure. We often work for Contractors to produce designs which result in successful construction in projects where the Owner’s engineer places the responsibility of design and construction on the Contractor.This paper is intended to inform both Owner and Contractor audiences of resources which are available to reduce the risks of trench collapse in difficult ground conditions. We hope it serves this purpose.DESIGNSubsurface InvestigationsSubsurface conditions should be defined by borings focused on definition of the soil profile and soil design parameters. After general subsurface conditions are defined, barrier borings should be drilled along the final alignment.Definition of Soil Strength and CompactnessCompactness of sand and gravel strata should be defined with Standard Penetration Test N-values. The shear strength of cohesive materials should be defined by laboratory testing. Silt and fine sand strata with little cohesion should be investigated using mud rotary techniques to prevent disturbance. General strength characterization by soil layer should be used for analysis of trench wall stability."

Jan 1, 2006

By David Pierce

The Port of Seattle, one of the largest on the west coast of North America, made a strong statement regarding their support for reusing existing structures when a decision was made to rehabilitate Pier 69, on Seattle&apos;s downtown waterfront, for their new headquarters. Because of its age and location, the pier provided an unusual challenge to the Port and its consultants. The Port hired Peratrovich, Nottingham, and Drage Inc. to design the seismic strengthening of the pier itself. To remedy the lack of seismic resistance in the 70-year-old pier, PN&D designed a new steel-pipe-pile supported concrete apron next to it. The structure relied on a development by PN&D, the "spin-fin pile", to achieve the tension capacities required of the batter piles. The construction of this apron was completed in October of 1991. Another team of consultants performed the superstructure renovation design, which is now under construction.

Jan 1, 1992

By Charles M. Wilk

"Mass stabilization involves mixing binding agents into marginal or contaminated soil to improve the subject material’s physical and/or chemical properties. This paper concentrates on the principles of soil mixing and benefits and application to new and existing rail right-of-way. Successfully applied in Scandinavia and other European countries, the soil mixing is now being applied in right of way in the northern latitudes of the U.S. and Canada. These regions have significant areas of “peaty” soils that can complicate construction and maintenance of rail and structure foundations. Mass stabilization can be used to improve the bearing strength of these soft soils for subsequent construction of railroads, pipelines, roads, and buildings. In civil engineering, the technology is often used to improve the construction properties such as bearing strength, of a marginal soil. In environmental engineering, stabilization is remediation treatment technology that protects human health and the environment by immobilizing hazardous constituents within the treated material. . The treatment is conducted while the subject material remains in-place (insitu). Mass Stabilization is often used to accomplish both civil and environmental purposes on the same project effectively addressing marginal soil while eliminating the expense of soil removal and replacement.This paper presents the principles of mass stabilization technology, implementation in the field and recent completed railway projects.The example rail projects will present the various benefits that soil mixing provides to railway construction and maintenance. Bench-scale studies and full scale implementation as well as soil construction properties before and after mass stabilization will be discussed. The paper and presentation will include information on the advantages of mixing methods and binding agent delivery systems.INTRODUCTIONNew or existing railroad right-of-ways may cross ground with low bearing capacity. Right of way subgrade undergo deflection (strain) as loads (stress) are applied (1). The amount of strain or deflection of the subgrade caused by loading of a train is proportional to the stiffness of the subgrade materials. Some soils, such as tamped ballast, are very stiff and resist loads well. Other soils such as soft clay, peat, or loose sand have low stiffness and undergo substantial movement under loads. It is very desirable to have the stiffest possible material in a track subgrade. Stiff subgrade material limits deflection under load, reducing track roughness and occurrence of track defects. Mass stabilization is a geotechnical method that can be used to improve the bearing capacity or stiffness of soil in these right-of-way. Mass stabilization involves mixing binding agents into soil subject to treatment while the soil remains in-place or insitu. Variations in the design or areas subject to treatment can be used to address transmission of vibration to adjacent structures."

Jan 1, 2017

By Allen Cadden

The type of soil we had was a silty fine sand. It had been placed by hydraulic methods in 1904 so it was quite clean I would say less than 10% silt the rest of it was very loose sand. That I&apos;m not certain, I&apos;ve only done it on sandy soils but it would stand to reason that some sort of a number should apply because you are measuring the amount of work that you are doing to it so if the soil is fairly consistent over the site it should be able to generalize from there but I don&apos;t know for a fact that it works. Well, verifying to ourselves that this method actually worked because we weren&apos;t certain at first when we were doing it so then we would develop the numbers and then check the results.

Feb 10, 2003

By Willie M. NeSmith

In the Metropolitan Atlanta Area today, augered, cast-in-place (ACIP) piles will be considered on most projects where deep foundation support is required. ACIP piles were first used in Atlanta in the late 1960s, and application began to blossom in the mid-1980s. Current design practice for ACIP piles is addressed in another paper in this conference. This paper describes the evolution of the ACIP industry in Atlanta, and details the use of ACIP piles on major projects in the Atlanta area.

Jan 1, 2003

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

By A. A. Gupte

Auger piling system which was developed in the United States in the 1940&apos;s is gaining acceptance in many parts of the world. Although primarily used to support foundations, the system is very useful for many other applications such as soil anchors, temporary and permanent earth retention systems, restricted headroom piling and underpinning of existing foundations. In this paper, review of current construction design techniques for the Auger piling system for earth retention and underpinning of structures is presented.

Jan 1, 1989

By Arvindh Gupta

BC Hydro proposed to improve the stability of the existing Seven Mile Dam with 54 corrosion protected, re-stressable anchors comprising 92/0.6? strands each, in phase 2 of the program. Being globally the largest capacity anchors ever build, coupled with extra ordinary specifications, the project was a challenge for the entire post tensioning industry. The paper discusses the challenges associated with the anchor material supply as per specifications, extensive research and development carried out by Con-Tech Systems ltd. to overcome the challenges and contribute in making the project a success. The substance of this article is published in the Aug/Sep issue of ADSC magazine.

Jan 1, 2004

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