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By Dennis Nottingham

The need for deep compaction of submerged granular soils has led to improvements in this area. In 1971, L.B. Foster Company personnel patented a method of deep compaction using a vibratory pile hammer and pile probe. The technique had some success, but did not produce consistent results and thus found its way to obscurity. Other patents attempted to modify the technique by various probe modifications, but again without measurable improvement from a practical point of view. Solutions to economical deep compaction up to 100 foot depths particularly in saturated granular soils would have a great impact on the construction industry and new bulkhead structures being developed, thus PND was prompted into related research and development. The advent of higher horsepower vibratory hammers, coupled with PND engineers? experiments, observations and measurements, led to an ?H? pile probe design which has produced measured soil density improvements up to 250% using SPT ?N60? values as a measure.

Jan 1, 2013

By KeerthiRaaj Subrmanian, Muthukkumaran Kasinathan

"A railway embankment is under construction between Nagapattinam to Thiruthuraipoondi covering 36.5 km. The sub-soil strata comprises of soft clay extending up to 10 m below existing ground level, which is subjected to stability and settlement problems. A trial stretch covering about 5 kilometer was improved using Prefabricated Vertical Drains (PVD) with surcharge was recommended to accelerate the consolidation settlement. The geotechnical characteristics of the subsoil are examined through laboratory tests on representative soil samples. Recent improvement in the finite element analysis has facilitated modeling of PVD in finite element software for computing the settlement magnitude and time rate of consolidation. In this study the theoretically predicted settlement magnitude and time rate of consolidation from Terzaghi.s vertical consolidation, Barron's radial consolidation are compared with the analyzed FEM results for both the cases with and without PVD improved embankment. The comparative analysis between FEM and predicted data hold good for stresses and the associated deformations. The excess pore water pressure was significantly lower and their dissipation was faster in case of embankment with vertical drains. Thus PLAXIS 2D tool shows fairly convincing results in comparison to the theoretical solutions.1. INTRODUCTIONFrom the earlier times civilization has been developed in a fashion either at the banks of river or near to the shore region, because of the easier availability of food and water. This over centuries made them as huge cities, consequently population rise made the increased necessity of highway, railways, port and even more ground for construction. As a stake researchers are pushed to make a low bearing ground into a massive carrier of skyscrapers, embankment, bridges etc. These low bearing ground suffers from total and differential settlement, slope instability. Hence, numerous ground improvement techniques were followed to eradicate these concerns which include preloading, piling, stone column, vertical drains and geosynthetic reinforcement. Among them Prefabricated vertical drain (PVD) are often used to accelerate consolidation of soft subsoil and has been the main soil improvement method used in improving the soft marine clay deposit (Chu et al.(2004); Chai (2001) and Arulrajah et al.(2003)). Literature review of embankment over soft clay deposit reveals that combination of PVD with preloading is widely considered as an economical and less time consuming ground improvement technique."

Jan 1, 2015

By Djk Arentsen

A new technique to drive tubular piles by impact hammer inside the pile has confirmed a dramatic reduction of noise and the opportunity to save steel. Also a reduction in driving time and a higher bearing capacity has been observed during a test program of this technique. As part of the so-called "Down-the-hole" driving technique, a wave equation analysis has been developed to calculate driveability and pile stress. The main feature of the new "Down-the-hole" technique is the development of a patented device allowing uncoupled penetration of pile tip and pile shaft, which makes it possible to drive both closed or open end piles and reduce the stress level induced in the pile wall. During a test program, a number of instrumented piles were driven and compared with traditional driving of the same pile with the same hammer on top (also instrumented). Also the stresses and performances were compared with precalculations. This paper, explains the technique and presents the test and noise results, in comparison with traditional top-pile-driving. The "Down-the-hole" driving technique is an interesting alternative for special applications where traditional pile driving requires a large wall thickness or in areas where noise is a hot item.

Jan 1, 1996

By Tae Hwan Lee, Jun-Shin Lee, Daejin Kwag, Sangchul Bang, Gerard T. Houlahan, Moo Sung Ryu

"Geotechnical engineers have been installing innovative, permanent underwater foundation systems utilizing suction buckets for the offshore industry since the early 1980s (Senpere and Auvergne, 1982). This foundation system has been successfully used on numerous and various types of offshore structures in a wide range of environments. Suction buckets have numerous advantages compared to conventional underwater foundation systems. The more notable advantages include easy installation, large loading capacity, low noise and retrievability. The application of reduced water pressure inside the bucket facilitates the installation of the suction buckets, where a suction pump attached at the top of the bucket can accomplish the entire driving operation. Because of this efficient operation, very large suction buckets can be driven into the seafloor, which eliminates the use of a large number of small piles.In Korea, one of the most economical and reliable renewable energy sources is wind power; however, onshore wind power generation has encountered many problems, such as the lack of favorable sites and public concerns about noise and environmental damage. Consequently, offshore wind power generation has attracted increasing attention due to its abundant potential, high efficiency of grid connection, and availability of easy expansion.In November 2011, the government of Korea announced a national offshore wind power development roadmap, which targeted its offshore wind power generation with the goal of becoming one of the top three nations in the world for offshore wind power generation. Korea Electric Power Corporation Research Institute (KEPRI) is the main research arm of the Korea Electric Power Corporation (KEPCO) and conducts research and development on electricity, power generation, renewable energy and other energy-related matters. KEPRI ultimately provides forefront knowledge and leadership to KEPCO with respect to energy and related areas for its near- and long-term needs. Financial support for the overall project, of which the suction bucket foundation system installed for the pilot phase wind turbine is described below, was provided from the New and Renewable Energy Program of the Korea Institute of Energy Technology Evaluation and Planning funded by the Korean Government Ministry of Trade, Industry and Energy"

Jan 1, 2017

By Tae Hwan Lee, Jun-Shin Lee, Daejin Kwag, Sangchul Bang, Gerard T. Houlahan, Moo Sung Ryu

"Geotechnical engineers have been installing innovative, permanent underwater foundation systems utilizing suction buckets for the offshore industry since the early 1980s (Senpere and Auvergne, 1982). This foundation system has been successfully used on numerous and various types of offshore structures in a wide range of environments. Suction buckets have numerous advantages compared to conventional underwater foundation systems. The more notable advantages include easy installation, large loading capacity, low noise and retrievability. The application of reduced water pressure inside the bucket facilitates the installation of the suction buckets, where a suction pump attached at the top of the bucket can accomplish the entire driving operation. Because of this efficient operation, very large suction buckets can be driven into the seafloor, which eliminates the use of a large number of small piles.In Korea, one of the most economical and reliable renewable energy sources is wind power; however, onshore wind power generation has encountered many problems, such as the lack of favorable sites and public concerns about noise and environmental damage. Consequently, offshore wind power generation has attracted increasing attention due to its abundant potential, high efficiency of grid connection, and availability of easy expansion.In November 2011, the government of Korea announced a national offshore wind power development roadmap, which targeted its offshore wind power generation with the goal of becoming one of the top three nations in the world for offshore wind power generation. Korea Electric Power Corporation Research Institute (KEPRI) is the main research arm of the Korea Electric Power Corporation (KEPCO) and conducts research and development on electricity, power generation, renewable energy and other energy-related matters. KEPRI ultimately provides forefront knowledge and leadership to KEPCO with respect to energy and related areas for its near- and long-term needs. Financial support for the overall project, of which the suction bucket foundation system installed for the pilot phase wind turbine is described below, was provided from the New and Renewable Energy Program of the Korea Institute of Energy Technology Evaluation and Planning funded by the Korean Government Ministry of Trade, Industry and Energy."

Jan 1, 2017

By Cau T. Bui

Thanks to Doi-moi (renovation) policy, many great bridges were constructed in Vietnam to meet demands of her booming economy in the recent decade and deep foundation structures were the only alternatives for the foundations of these great bridges. The deep foundation structures were constructed by modern technologies and almost of all these deep foundation structures were designed by foreign companies and carried out by Vietnamese workers and engineers under supervision of foreign experts. Beside successes, there were several failure cases in which the collapse of temporary scaffolding system of Can-tho Cable ? Stayed Bridge due to settlement of its pile foundation killing 54 workers and seriously injuring 80 other workers was the most serious. This paper introduces construction techniques of the deep foundation structures applied to building of great bridges in Vietnam recently. It will especially focus on two failure cases: 1) collapse of temporary scaffolding system of Can-tho Cable ? Stayed Bridge due to settlement of its pile foundation and 2) failure of drilled shaft foundation of Thanh-tri bridge due to poor construction technique and management. These two failure cases were greatly concerned by both bridge specialists and the public. Reasons of and lessons from these two failure cases will be carefully discussed. From the two failure cases, this paper will draw some lessons that should be important issues to be seriously paid attention when designing and constructing deep foundations in Vietnam.

Jan 1, 2008

By Abdelmalek Bouazza, Aamir Mahawish, Will P. Gates

Bio-grouting by means of microbial induced calcite (calcium carbonate) precipitation (MICP) to improve mechanical properties of granular soils has gained much attention in recent years. The biogrouting process offers an alternative and environmentally friendly approach to conventional soil improvement techniques, such as cement. Bio-grouting by urea hydrolysis has been extensively applied to tackle various geotechnical problems. However, it has yet to be applied to improve engineering properties (compressive strength) of a coarse cohesionless material with the aim using it as sand/stone columns within soft and very soft soils. This paper investigates the effect of using light, moderate and heavy biochemical treatments on the unconfined compressive strength (UCS) of coarse sand columns. In addition, the microstructure of the bio-cemented coarse material has been analysed by X-ray computed tomography (XRCT). The experimental results revealed that the UCS could reach up to 200kPa, 1000kPa and 5500kPa for light, moderate and heavy bio-cemented coarse sand columns, respectively. The microstructure investigations showed that the deposited calcium carbonate can be identified using XRCT imaging and can be associated with the gain in UCS values. Various microstructure properties, such as void ratio, dry density and porosity were also identified and compared with the laboratory data.

Jan 1, 1900

By Jesús E. Gómez

A total of 260 micropiles were installed as part of a retrofit effort for two existing bridges. The micropiles consisted of hollow core bars installed under limited headroom conditions. Of the total number of micropiles, 180 were installed in submerged sand and 80 were installed in stiff, silty clay. The micropiles were drilled using a lean cement grout which was re-circulated for de-sanding and re-use. Final grout was injected upon completion of drilling to the design tip elevation. The micropiles were subject to a rigorous quality control that included grout quality testing and proof-testing of each production micropile. This paper presents a description of the procedure for installation and quality control of the micropiles. The successful proof-testing of all the production micropiles showed that hollow core bar micropiles can be used effectively in granular and fine-grained soils. Hollow core bar micropiles offer particular advantages when installed in submerged sand formations with respect to other traditional micropile types. The results of the proof load tests are presented in a companion paper.

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 Paul J. Lewis

Estimation of the axial side shear resistance of drilled shaft rock sockets is directly related to the unconfined compressive strength of the bedrock. Commonly, the mean unconfined compressive strength value is calculated from a range of laboratory test results and is used to estimate the side shear of the bedrock. This paper presents the results from a full scale axial load test performed on an 8.5-feet-diameter drilled shaft rock socket, and compares measured side shear values to estimated values for two different rock strata. Measured side shear values correlated well with the design value calculated for the ?strong? rock stratum, but did not correlate well with the design value calculated for the ?weak? rock stratum. The mean unconfined compressive strength was used to calculate the side shear in both strata, but review of the laboratory data indicates that this value may not have been appropriate for the weak stratum due to a large variation in the laboratory test results. Also included in this paper is a discussion of the subsurface conditions, the laboratory test results, and the methodology used to design the drilled shaft rock sockets for axial and lateral resistance.

Jan 1, 2013

By Mohamad H. Hussein

A minipile system was employed in underpinning a historical structure in Florida. The existing structure is founded on shallow foundations. Subsurface conditions at the project site consist of deep organic deposits interbedded with loose sand and silty sand. A minipile foundation system was deemed the most appropriate underpinning corrective measure for the already badly cracked structure. A total of 68 minipiles, 3.5 inch OD and 0.25 inch wall thickness closed-ended concrete-filled steel pipes, were installed to depths varying from 55 to 175 feet. Installation was accomplished with a pile driving hammer having a rated energy of 1 kip-ft. Highest required pile design load was 15 kips. Conventional static and wave equation analyses were performed to establish preliminary pile lengths, to assess pile drivability and establish driving resistance criteria. Dynamic pile testing using the Pile Driving Analyzer was conducted on six of the production piles. This paper describes geotechnical design considerations, installation procedures, and dynamic field monitoring. This case represents unique applications of pile dynamic testing and such slender, very long minipiles in compressible soils.

Jan 1, 1993

By Ben C. Gerwick

This publication is intended to document recent innovations and technologies that have the best potential for effectively improving the quality of marine foundations while reducing the cost, time and risk of construction. Marine foundations originated in Neolithic times with the Swiss Lake Dwellers who constructed pile-supported houses, safe from invading tribes. The Queen of Babylonia built the first recorded bridge in 1500 BC across the Tigris. The foundations were large flat stones laid on the river bottom. About the same time in India, builders extended their water well techniques to the construction of ?well? foundations in the beds of their rivers. These were really the first open caissons; brick walls were built up in a circular ring while divers excavated sand from the bottom, sometimes at a depth of 100 feet. The Romans extended the clay-filled cribs of the Middle East to shallow cofferdams, which they sealed by underwater concrete made with pozzolanic cement from Mt. Vesuvius.

Jan 1, 2013

By H. Hayashi, M. Yamaki, H. Hashimoto, T. Yamanashi

"In an experiment on a trial embankment, the deformation mode of the improved ground at the toe of the embankment was compared with the deformation mode of the unimproved ground. This comparison showed that the behavior exhibited by the improved ground was the same as that exhibited by the unimproved ground, despite the low improvement rate (ap = 10%) of the ground improvement. Thus, the improved ground and the unimproved ground were found to be functioning as composite ground. Further, the strain that developed in the geo-textile used for the crushed-stone mat was considerably less than the strain specified by the design strength. As a result, it was found that a crushed-stone mat can serve as a mattress.OVERVIEW OF THE TEST CONSTRUCTIONLow Improvement-Rate Soil in Combination with Crushed-Stone MatIn Hokkaido, approximately 2,000 km2 of the land is peat land, an area almost as large as Tokyo. Such land accounts for 6% of Hokkaido’s plains and 2.4% of its total land area. The peat layer is normally 3 to 5 m thick and underlain by a layer of soft, cohesive soil whose thickness may exceed 20 m. In such a ground, consolidation using cement may generate differential settlement between improved soil as a result of embankment construction or lateral deformation caused by the slipping of unimproved ground. Therefore, the improvement ratio (ap) is designed to be at least 50% by the Manual for Construction on Soft Peaty Ground (CERI, 2011 [1]). Consolidation of ground with a low improvement ratio in combination with crushed stone-mat installation is a measure for soft ground (Figure 1). In this method, soil with a lower Improvement ratio than that of conventional improved soil (e.g., ap=10%) is placed beneath the entire embankment and a “crush stone mat”, a layer of crushed stone (t=0.5 m) enclosed by geo-textile, is then placed between the embankment and the soil."

Jan 1, 2015

By Wang Mingshu

The pile foundation is a kind of advanced foundations in the filled or soft soil. In this paper, through the actural engineering of coal dressing plant of Western Opencast Coal in Fushun built on the mining dump with large diameter pile foundation, the construction method and mechanics analysis of pile are given. Unless it is in following stadge, the stability of pile cannot be lost due to its small rigidity. The analysis shows that pile foundations of large diameter ellipse section can decreased hotizontal displacement to 60% ?70% of that of equal section an in the design of a single pile and a single column, the ellipse pile and manual dig hole are most favourable. So a large amount of concrete can be saved.

Jan 1, 1991

By Brad W. Taylor

"During the past several months, I have introduced to civil and structural engineers an innovative solution for the integrity testing of concrete using the Thermal Integrity Profiler (TIP) Wire Cable System by Pile Dynamics. While in the process of “educating” highly-trained professionals about a technological breakthrough, I ended up being educated myself about their needs for quality control/quality assurance (QA/QC). With that in mind, I would like to focus on their two key areas of concern:• How complex is the TIP installation process?• How does the QA/QC engineereffectively analyze and report TIP test results?A few months ago, during a discussion with a senior QA engineer, he asked a question that stopped me in my tracks: “Why should we do foundation testing at all?” Turning it around, I asked, “Why wouldn’t QA/QC personnel want to know everything they could about their critical infrastructure foundation?” Honestly, I didn’t answer his question nor did I fully comprehend what he was trying to say. With his experience, the engineer understood that there has not been an integrity test or a combination of integrity tests that could deliver an inside the cage and outside the cage (cover) complete data set that would provide a definitive profile of the entire shaft. Crosshole sonic logging (CSL) becomes more effective the larger the diameter of the shaft becomes, with a maximum effectiveness between 70% and 80%, but does not provide any data of the integrity of the shaft beyond a straight line between CSL tubes. Gamma-gamma logging (GGL) provides qualitative information about the concrete surrounding the GGL tube and device, and it provides information about a small percentage of the drilled shaft concrete near its outside edge."

Jan 1, 2017

By Walter Kaeck

In a recent upgrade of their system, Amtrak converted a bascule type draw bridge over the Thames River to a vertical lift structure supported by the existing piers. During the bridge replacement, significant settlement occurred on one of the piers and movement continued thereafter. Construction was stopped as Amtrak became concerned as to how much the subsequent construction activities would cause the pier to further settle and tilt, not only impacting the operation of the existing bridge, but also jeopardizing the new lift span. Mueser Rutledge was engaged at this time to help understand and solve the problem. A remedial grouting program was developed to arrest the settlement. As a subcontractor to Cianbro Corporation, Pittsfield, ME, The Judy Company was hired to perform the remedial grouting work. Work platforms were constructed around the pier for support of the drilling equipment. A dual string drilling system was used to install sleeve pipes at depths of up to 185? below the water level. Ultrafine cement grout stabilized with additives was placed at 2.5 foot intervals through the depth of the sand and gravel stratum below the bottom of the pier. Logistics were difficult and the schedule was severely impacted by the remedial work, necessitating working six 12-hour shifts per week and working in the river through the winter months. After four months of drilling and grouting, movement of the pier stopped. At the conclusion of the remedial work, more than a million gallons of ultrafine cement grout were placed. Confirmation borings recovered completely solidified material with compressive strengths ranging from 500 to 1500 psi. The bridge replacement was then completed and is functioning. Continued monitoring through July 2009 shows negligible movement.

Jan 1, 2009

By Lance Helwirg

New high and low double outfall bridge structures for a juvenile fish bypass system have been constructed on the Washington Shore approximately two miles downstream from the Bonneville Dam on the Columbia River. The high and low outfalls each extend approximately 400 feet into the river from the Washington shore and are designed to release juvenile salmon into the river at above-water discharge elevations for improved survival rates. The two outfall structures include post-tensioned concrete double box flume girders approximately 7 feet high by 13 feet wide, which will be submerged in river flows as high as 15 feet per second. Each of the 6 offshore foundation piers is composed of a single 10-foot diameter reinforced concrete drilled shaft with a permanent steel casing embedded into the river bottom approximately 100 feet. Challenging outfall design conditions included designing the entire structures to be submerged for long periods of time in 15-feet-per-second river water flow with a 60-foot cantilever at the end of each outfall, and with the superstructure 70 to 80 feet above the river bottom. Figures 1-1,1-2, and 1-3 show the high and low outfall structure overhead photos and elevation view.

Jan 1, 2001

By Tomohide Takeyama, Binh T. T. Nguyen, Masaki Kitazume

"Deep mixing columns are widely used to support embankments constructed on soft ground area. Researches on the stability of deep mixing columns were done by some authors when the columns do not simultaneously fail but individually fail at different time. A layer of shallow mixing is proposed to reinforce these columns as a group to increase the stability as well as loading capacity of columned improved area. Two centrifuge model tests were done to observe the effect of shallow layer on reducing embankment displacement as well as on failure pressure of improved ground. Acrylic piles were used as deep mixing columns in the centrifuge tests to avoid unexpected internal failure of columns. The results of centrifuge tests were also simulated by 2D FEM to back-analyze the centrifuge experiments. A good agreement between the centrifuge experiments and the numerical simulations shows that by using a shallow layer reinforcing individual columns, the horizontal displacement at the embankment toe reduces by 60 % and the tilting failure is clearly indicated in columns without shallow layer. Although, no significant failure was observed under the current centrifuge condition, the failure pressure of improved ground was significantly increased with the columns reinforced by shallow layer.INTRODUCTIONCement or lime and soil mixing technique was firstly used in Japan and Nordic countries since 1970s. The technique is used to improve soft soil by increasing its mechanical properties including strength and consolidation characteristics (Kitazume and Terashi 2013). Various researches were done to investigate the characteristics of mixing material due to various factors including types of binder, condition of soil, mixing condition and curing condition (Terashi 1997). On the other hand, many studies focused on the application of in-situ mixing technique such as supporting embankment and underground structure as well as working as the foundation of building and factory (Kitazume and Terashi 2013). In term of embankment supporting, column-type improvement is taken into account for huge applications. Due to loading from embankment, the deep mixing columns tend to fail either external failure (Kitazume and Maruyama 2006) or internal failure (Kitazume and Maruyama 2007). However, the deep mixing columns do not fail simultaneously but instead one by one at different time (Kitazume and Maruyama 2007). Because the deep mixing columns work and fail individually, the strength and stiffness of all columns cannot be mobilized simultaneously. By using a shallow mixing layer fixing the top of deep mixing columns, individual columns may work simultaneously. A combined technology of shallow stabilization and floating-type cement treated columns is used to reduce settlement of a high embankment on soft ground (Ishikura et al. 2007). A research on effect of surface improvement layer on internal stability of group column type deep mixing improved ground under embankment load was reported in the Port and Airport Research Institute, Japan (Kitazume 2011). However, the failure pattern of shallow and deep mixing combined structure has not well studied. This research focuses on the external failure mechanism of the combined structure by centrifuge model tests and back-analyzed simulation using 2D finite element method. The effect of shallow layer on embankment displacement and the yield point of the improved ground is also discussed in this study."

Jan 1, 2015

By Jiun-Yih Chen

Pile load tests are regularly used to verify pile capacities. Sometimes, they are used to optimize pile designs. This paper presents a case study based on a real project, in which the information obtained from load tests during construction was used to shorten the design pile lengths without a formal decision analysis. In this study, a simple probabilistic model was used to assess the probabilities of failure based on design information. The Bayesian approach was used to update the probabilities given the additional information from load tests. These probabilities were then used in a formal decision analysis to determine the optimal pile lengths based on design information and based on the additional information from load tests. The optimal pile lengths are different from those implemented in the project without a formal decision analysis. The value of the formal decision analysis is illustrated by its ability to optimize the pile length in a transparent and defendable way.

Jan 1, 2009

By Mike Muchard

A design phase load test program was performed at the Broadway Viaduct bridge site to evaluate load carrying capacity and constructability of post grouted drilled shafts. The program included construction, instrumentation, post grouting and load testing of three drilled shafts. Two shafts included sleeve port and plate base grouting apparatus and were post grouted. The third shaft was un-grouted and served as a control shaft for comparison of the un-grouted end bearing. The shafts were 5 feet in diameter with the control shaft at 55 feet in length and post grouted shafts at 55 and 66 feet. SPT borings at the centerline of each test shaft defined geotechnical conditions at each shaft. Test shafts were instrumented with strain gages and concrete integrity was evaluated with crosshole sonic logging. Instrumentation and data acquisition was used during the post grouting operation to fully capture the shaft behavior. Finally, Statnamic load testing was performed on all three shafts to their ultimate capacity. The fine to coarse sandy soils in which the shafts were tipped in were well suited to improvement from post grouting. Grout pressures of 660 psi were achieved with 0.08 inch or less of upward shaft movement. Subsequent Statnamic load tests showed 183 to 192 percent greater end bearing in the post grouted shafts as compared to the un-grouted shaft. The overall result showed a potential savings of approximately 9 feet to 35 feet of drilled shaft length in addition to the increased quality assurance from post grouting.

Jan 1, 2009