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By Mai Yuanjian

The stabilization effect in large excavation slope with vacuum wellpoints system during construction of a dry dock located in Guangzhou is introduced in this paper. In-situ observations indicate that the effect of wellpoints for decreasing seepage in slope is remarkable even though the muddy sitty clay in it has poor permeability and the slope can remain its stability well. Meanwhile, a non-linear partial defferential equation has been set up to the whole unsteady seepage process as water level in the foundation pit excavated under water goes down to the bottom and so does the seepage in slope due to dewater by vacuum wellpoints system at the same time. And the finite-defference method has been used to solve the equation mentioned above, which differes from conventional wqy where the equation will be linearized firstly. Since the water heads in slope with wellpoints dewatering are more variable, it is necessary to keep non-linear. The calculation results are in good accordance with observation. Vacuum wellpoinnts for slope stabilization in this work is successful.

Jan 1, 1991

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 K. Englehardt

J BERESFORD introduced the subject of the paper which is the use of polymeric slurries to support the sides of diaphragm wall and bored pile excavations during construction. In the opinion of the authors the use of a suitable polymeric fluid offers financial and technical advantages compared with traditional bentonite based slurries. Under quiescent conditions a support slurry must have the following properties. - sufficient viscosity to support the sides of the excavation, to prevent infiltration into soils and to hold loose soil particles in suspension. - when agitated it should thin quickly to assist pumping transfer and cleaning and allow free passage of the grab or drill. - viscosity should be low enough during concreting to facilitate placement but high enough to prevent contamination of the concrete.

Jan 1, 1991

By Stefan K. Schwank

The paper describes the two foundation techniques - mini piles and postgrouted bored piles. The mini pile system is presented with its design and installation parameters, especially the drilling technique. Two case histories demonstrate the application under extremely limited space and traffic conditions and the required modifications of the equipment. After the description of the postgrouted bored piles and its grouting technique, the paper gives a comparison of postgrouted piles and standard piles on a large basic test in Germany. The Brooklyn Queen's Expressway, N.Y., case history shows the application of this technique after redesign of the original proposal. 1. General Increasing requirements to improve existing foundations to carry additional loads and to increase the bearing capacity of bored piles leads to two new piling techniques: the mini-pile and the post grouted bored pile.

Jan 1, 1991

By Lu Peiyan

A computation model of soil-pile (wall) interaction under lateral loading is presented in this paper. The model has been applied to some engineering projects, and the comparison between computation result and measured result shows good agreement, so the model is proved to be correct and practical.

Jan 1, 1991

By Michael W. Neill, O&apos

Drilling slurry has become an effective aid to the construction of drilled shafts in caving and/or waterbearing soils. Historically, drilling slurry made of bentonitic clay and water was first used in the US in water well drilling as early as 1889. In coastal Texas drilled shaft contractors began using slurry, often made of on-site clay mixed with potable water, in the years following World War II, on a relatively routine basis. This type of slurry was used to "process" boreholes, in which the borehole was drilled "in the dry" until water or unstable soil was encountered, after which water and on-site clay were introduced into the borehole and mixed in place with the auger or other drilling tool. Drilling then continued under a slurry consisting of the uncontrolled mixture of clay and water until the excavation had reached a relatively impermeable and cohesive material. At this point, a steel casing was dropped into the hole and sealed into the lower stratum of impermeable geomaterial (soil or rock). The slurry inside the casing was bailed or pumped out, drilling continued to plan depth in the dry, a reinforcing cage was set in the partially cased borehole, concrete was placed and the casing was withdrawn. Some soil-slurry was undoubtedly trapped between the casing and the borehole wall, but the quality of that slurry was usually of no concern, because engineers of the period usually viewed drilled shafts as nothing more than deeply buried footings. Any unejected slurry would only serve to lower side shearing resistance, not yet considered in design, but would have no effect on end bearing. In the 1960 's the effectiveness of soil-slurry came into question because it was often ineffective in maintaining borehole stability at marginal drilling sites and because the economy of using shaft resistance, in addition to end

Jan 1, 1991

By William S. Gardner

It is certainly an honor to have been invited to address the Deep Foundation's Annual Meeting on such a vast and weighty topic as "Present to Future Design Considerations of Deep Foundations." Acknowledging the enormity of this 30-minute assignment, I hope to at least scratch the surface of the topic deep enough to generate some thought and reflection. Design considerations, be they current or future, bring to mind a number of important subtopics which comprise the design process. As shown by Figure 1, a flow chart of this process describes, in general terms, the sequence of a deep foundation design.

Jan 1, 1991

By Li Keqiang

Among the pile foundations of the 156 tall buildings over 18 storeys in Shenzhen, 86. 5% of them are constructed by slurry drilled piles, bored piles and excavated piles (hand-dug caissons). Based on the experiences of the engineering practices, the paper points out that the main quality problems of pile foundations in Shenzhen are: insufficient bearing capacity of single pile; poor concrete quality of pile; damage of the precast pile; pile tip not reaching the required bearing stratum and the thickness of bored/drilled sediment exceeding the specified. etc. The quality inspection methods that have been used include: check of construction records and excavating; static loading test; core sampling test; non-destructive test, etc. Treatments of quality problems used in Shenzhen are also introduced in this paper.

Jan 1, 1991

Jan 1, 1991

By W. G. K. Fleming

Mr P. Bermingham introduced paper 9.1, describing the development and trials of a new pile load-testing technique that the Authors had termed "Statnamic". The system involved launching a test weight mounted on the head of the pile by igniting chemical fuel in a pressure combustion chamber between the pile head and the test weight. The expansion products from the burning fuel generated large pressures which were used to launch the weight upwards at high velocity. The reaction from this force generates an equal and opposite force at the pile head. This force is typically of much longer duration compared with, for instance, dynamic load testing by drop hammer. In addition the pile experiences a much lower acceleration - typically of less than one g. Because of the long duration blow, the pile is loaded at below its natural frequency and is therefore under a uniform high stress over its full length throughout the duration of the test. The pile behaviour is not dominated by the complex action of an impulsive stress-wave as with standard dynamic testing. The test technique is thus essentially quasi-static. It was anticipated that a ram test weight of 16 tonne would be sufficient to provide the test reaction for a 600 tonne load test. It was pointed out that the device was still at the research stage, but had yielded encouraging results to date. Testing would proceed from model testing and computer simulation to full scale field testing.

Jan 1, 1991

By William J. Neely

Augercast piles are formed by drilling a continuous-flight auger into the ground and, on reaching the required depth, sand-cement grout or concrete is pumped down the hollow stem as the auger is withdrawn. The sides of the hole are supported at all times by the soil-filled auger, eliminating the need for temporary casing or bentonite slurry. The augercast piling method is fast and economical; there is no vibration, very little noise and, if executed properly, no ground displacements during installation. The method is well suited to sands which are easy to drill and are readily transported up the auger. Relatively little attention has been given to augercast piles in the literature which might be part of the reason for the considerable variations in local practice, building code requirements and design methods. The purpose of this paper is to discuss some of the features of augercast pile installation that are known to influence both the structural and geotechnical capacity of the pile, to evaluate several empirical design methods and to look at some important aspects of quality control of augercast pile installation.

Jan 1, 1990

By Thomas M. Gurtowski

This paper presents a summary of allowable bearing pressures and skin friction values that have been used to design drilled pier foundations for support of high-rise structures in downtown Seattle, Washington. These design parameters are based upon a review of geotechnical reports and records of more than 20 building projects. The following pages present a description of the soils encountered at these sites including foundation bearings soils, and design bearing and friction values. The accumulated data is summarized in Table 1, and the locations of the buildings are shown in Figure 1. A detailed description of the construction of two belled drilled piers are presented illustrating typical methods and procedures used in downtown Seattle. The two cases are from the Washington State Convention and Trade Center (WSC&TC). SEATTLE AREA SOILS The Puget Sound area was subjected to several major glaciations during the Pleistocene Epoch. Glacial ice originated in the cordilleran and coastal mountains and the Vancouver Range of British Columbia. The maximum southward advance of ice reached the area about halfway between Olympia and Centralia. As a result of these glaciations, the Puget Lowland was filled to significant depths by glacial and non-glacial sediments during the Pleistocene.

Jan 1, 1990

By James J. Anderson

In this talk I will report on an effort to reassess the risk of pile driving to juvenile salmonids migrating through Puget Sound. The study was motivated by the concern of the construction industry that provisions restricting pile driving during the spring migration is resulting in an unbalanced burden to the industry. In simple terms the industry wants to know if some construction can be conducted in the spring without harming the juvenile fish. Fisheries agencies have agreed to reconsider their regulations in the context of additional studies. So, in this talk I will present some thoughts on risk assessment in general and the results of our study to assess the impact of pile driving on Snohomish River juvenile pink and chum salmon that migrate through the Navy Homeport construction site at Everett. The research, which is being carried out by the Fisheries Research Institute at the University of Washington, was planned and is supported in a joint effort including: the Washington Department Fisheries, National Marine Fisheries Services, U.S. Fish and Wildlife Service; General, Manson, and Hurlen construction companies, the Department of Transportation and a number of Puget Sound ports authorities. I will first briefly discuss the early life history of the juvenile salmon the regulations are designed to protect Second, I will outline the legal criteria required for risk regulation and some specific thoughts on how a reassessment of pile driving risk might be approached. With this basis I will report on our research and how it can be applied to a new risk assessment.

Jan 1, 1990

By Joan Stoupa

The expansion of the West Point wastewater treatment plant located in Seattle, Washington, will require a permanent tieback retaining wall to enlarge the plant site for the new treatment plant facili­ties. The retaining wall will extend approximately 3,000 feet along the property boundary between the treatment plant and the neighboring Discovery Park. Wall heights will range from 35 to as high as 65 feet. The purpose of the retaining wall is to provide a more uniform grade on the plant site and to resist lateral pressures exerted by the upslope, unstable hillside. During preliminary design of the retaining wall, various wall systems were evaluated based on assumed subsurface soil conditions. Results of preliminary studies indicated that expected subsurface conditions and wall heights made a permanent tieback retaining wall feasible. However, uncertain loads on the wall and the capacity of anchors in the native soils were significant. As a result, a detailed geotechnical program was conducted. The scope of the program included conventional drilling, sampling, analyses, and a field test program to determine site-specific anchor capacities. This paper describes the anchor test program and results.

Jan 1, 1990

By Jay A. Berger

Nondestructive testing of deep foundations for integrity problems made great strides in the late 1980's. Inexpensive portable computers have allowed the immediate and rapid processing of field measured acceleration records which can provide insight into the relative structural integrity of a previously installed foundation member. Although the gathering, processing and displaying of the data is now straightforward, interpretation remains at times rather challenging. This paper provides a brief introduction into the theoretical basis for data interpretation and the hardware necessary for data acquisition. Five case studies are discussed which demonstrate the varied applications of low strain integrity testing of deep foundations and the efficiency at which they are completed. BACKGROUND One dimensional wave mechanics, when applied to a linear elastic pile with a length that is an order of magnitude greater than its width, provides a straightforward basis for the interpretation of motion measurements made at a pile top. When impacted, a stress wave travels through the pile at a wave speed, c, which is a function of the elastic modulus, E, and mass density p (i.e., E=pc2). The applied load F, and particle velocity v, at a point are related by the equation F=Zv. For a cross-sectional area A, the proportionality constant Z is equal to EA/c. Because Z is a measure of the pile's resistance to change in velocity it is called the pile impedance.

Jan 1, 1990

By Bengt H. Fellenius

The design of pile foundations is much more commonly verified by means of a full-scale test, than is the design of other foundation units. The reason is not that our knowledge of pile behavior is more uncertain than our knowledge of other foundation types making the verification necessary, but more that the loads in a structure are more concentrated to single foundations in a structure founded on piles as opposed to structures on footings or mats. Therefore, should a pile cap fail or move, the adverse consequence of this is often drastic, as the piled structure has little freedom to transfer its need for support to other foundation units. Consequently, it becomes important to assure the design of piled foundations. In many, maybe in most instances, the static pile loading test is routine and geared toward determining an at least capacity, only. However, in these times there is an ever increasing liability of the professional, demands for increased economy of the foundation, and frequent lack of the involvement in the test of the experienced old-timer exercising good judgment. Furthermore, modern pile design is leaving the single, simple concept of capacity and requires more information from the test to assist in determining aspects of long-term behavior and settlement. Therefore, even the straight forward, routine static loading test requires improved planning, execution, and analysis.

Jan 1, 1990

By Patrick J. Hannigan

The pile foundation designer typically performs a subsurface exploration program and static pile capacity calculations before selecting a pile foundation type, length, and capacity. During construction, a pile installation criterion must be established to meet these design requirements. This installation criterion usually consists of a minimum penetration resistance or blow count to confirm pile capacity and may also include a minimum embedment requirement. This text will focus on use of wave equation analysis and dynamic measurements to meet design requirements. BEFORE THE WAVE EQUATION Since the mid-1800s, over 450 dynamic formulas for pile driving control have proliferated. In their simplest form, these formulas relate hammer energy to the work of soil resistance, or simply: W ? h = R ? s (1) Where W = ram weight h = ram drop height or stroke R = pile capacity s = pile penetration per blow

Jan 1, 1990

By Dennis Nottingham

Spin-fin pipe piles can develop large loads in tension, thus have evolved as a foundation product of great potential. Currently, over 500 spin-fin piles have been used successfully in dolphins, docks, buildings and bulkheads. Spin-fin piles are pipe piles with plates welded near the tip at a batter-in-screw fashion. Thus, as the pile is driven, the pile screws into position. Tests show this pile type to have highly unusual stress/strain relationships, wherein plunging failure is usually never reached either at normal or large deformations. Tension capacity can approach pile capacity in bearing; thus, large reserves are usually available for tension. Tests have been performed on 8-5/8-inch to 24-inch-diameter piles in silt, sand, and gravelly soil, to provide a broad spectrum of data.

Jan 1, 1990

By John F. MacDonald

From 19BS thru the present, Guy F. Atkinson Construction Company has been involved in several transportation construction projects in the Seattle area. Two of these contracts, the Mt. Baker Ridge Tunnel, and The Seattle Bus Tunnel, had unique foundation features. MT. BAKER RIDGE TUNNEL ACCESS PITS The Mt. Baker Ridge Tunnel is part of the general upgrading of the I-90 freeway between I-405 and I-5 (see Fig. 1). It is located on the western shore of Lake Washington and consists of a 1300 foot long large diameter tunnel thru Mt. Baker Ridge. The ridge consists of over consolidated silts and clays overlain by a loose to medium dense silty fine sand. The water table is perched in this upper layer of material. The clays of Seattle have a history of being very sensitive to excavation. The hills are marginally stable and numerous landslides have occurred recently in the area of the tunnel. [ ]

Jan 1, 1990

By Alan Alhadeff

Why is mediation being hailed as the wave of the future? The high cost of putting on a trial, over-crowded court calendars and long trial delays have resulted in what prominent attorneys and leading jurists are calling a litigation crisis. In no segment of the legal world are these pressures greater felt than in the trial of the serious construction case. Furthermore, the siege mentality of both the plaintiff and defense bar often leads to a reluctance by either side to make the first reasonable offer for fear of showing weakness. Attorneys operating in the serious construction case arena express concerns that there exist insufficient opportunities for the parties to meet, tell their stories, and negotiate settlement prior to the eve of trial. Mediation, by opening lines of effective communication and encouraging meaningful settlement negotiation, has proven to be a very effective antidote to the litigation crisis.

Jan 1, 1990