1、Report on Design and Construction of Drilled PiersReported by ACI Committee 336ACI 336.3R-14First PrintingAugust 2014ISBN: 978-0-87031-914-3Report on Design and Construction of Drilled PiersCopyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not
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11、e Practice (MCP).American Concrete Institute38800 Country Club DriveFarmington Hills, MI 48331Phone: +1.248.848.3700Fax: +1.248.848.3701www.concrete.orgThis report covers design and construction of 30 in. (760 mm) diameter or larger foundation piers constructed by excavation of a hole in a subgrade
12、that is later filled with concrete. The 30 in. (760 mm) diameter boundary is an arbitrary size; smaller-diameter drilled piers can be designed and installed in accordance with ACI 543R. Although determination of overall pier size and concrete section design are two basic drilled pier design procedur
13、es, emphasis is focused on the determination of overall pier size, which is affected by the interaction between subgrade and pier. Because pier capacity is significantly affected by construction means and methods, the licensed design professional should understand these limitations. Construction met
14、hods described include excavation, casing, reinforcing steel installation, and concrete placement. Acceptance criteria and recommended procedures for construc-tion, engineering, and evaluation are presented.Keywords: bearing capacity; caisson; casing; excavation; foundation; geotechnical engineering
15、; lateral pressure; lining; slurry; tremie.CONTENTSCHAPTER 1INTRODUCTION AND SCOPE, p. 21.1Introduction, p. 21.2Scope, p. 2CHAPTER 2NOTATION AND DEFINITIONS, p. 22.1Notation, p. 22.2Definitions, p. 2CHAPTER 3GENERAL CONSIDERATIONS, p. 33.1General, p. 33.2The structural and geotechnical teams, p. 33.
16、3Factors to consider, p. 43.4Pier types, p. 43.5Geotechnical considerations, p. 5CHAPTER 4DESIGN, p. 74.1Loads, p. 74.2Loading conditions, p. 84.3Vertically loaded piers, p. 94.4Laterally loaded piers, p. 94.5Piers socketed in rock, p. 154.6Strength design of piers, p. 164.7Pier configuration, p. 16
17、CHAPTER 5CONSTRUCTION MEANS AND METHODS, p. 175.1Excavation and casing, p. 175.2Placing reinforcement, p. 185.3Dewatering, concreting, and removal of casing, p. 185.4Slurry displacement method, p. 195.5Safety, p. 21CHAPTER 6CONSTRUCTION ENGINEERING AND TESTING, p. 226.1Scope, p. 226.2Geotechnical fi
18、eld representative, p. 226.3Preconstruction activities, p. 226.4Construction geotechnical engineering procedures, p. 236.5Concrete placement, p. 25William H. Oliver Jr., Chair Bernard H. Hertlein, SecretaryACI 336.3R-14Report on Design and Construction of Drilled PiersReported by ACI Committee 336Cl
19、yde N. Baker Jr.William D. BrantDiane M. CampioneJoseph P. ColacoConrad W. FeliceRudolph P. FrizziShraddhakar HarshMatthew JohnsonJohn W. JohnstonJohnny H. KwokHugh S. LacyAdam C. RammeSatish K. SachdevRodrigo SalgadoHarold R. SandbergEdward J. UlrichConsulting membersRonald W. HarrisJohn F. Seidens
20、tickerACI Committee Reports, Guides, and Commentaries are intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and w
21、ho will accept responsibility for the application of the material it contains. The American Concrete Institute disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising therefrom.Reference to this document shall not be made in co
22、ntract documents. If items found in this document are desired by the Architect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer.ACI 336.3R-14 supersedes ACI 336.3R-93 and was adopted and published August 2014.Co
23、pyright 2014, American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by electronic or mechanical device, printed, written, or oral, or recording for sound or visual reproduc-tion or
24、 for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors.16.6Post-construction assessment, p. 276.7Reports, p. 276.8Criteria for acceptance, p. 276.9Corrective measures, p. 28CHAPTER 7REFERENCES, p. 28Authored documents, p. 28CH
25、APTER 1INTRODUCTION AND SCOPE1.1IntroductionThis report addresses design and construction of drilled pier foundations constructed by digging, drilling, or other-wise excavating a hole in the subgrade that is subsequently filled with plain or reinforced concrete. Although structural design and constr
26、uction of drilled pier foundations are the primary objectives of this report, relevant aspects of geotech-nical engineering are also discussed, as variations in subgrade properties have a critical influence on design, construction, and subsequent performance. Successful drilled pier design, construc
27、tion, and performance requires reliable data on the applied loads and supporting subgrade. Because construc-tion limitations often govern design, combined cooperation among the geotechnical engineer, structural engineer, and drilled pier contractor are essential.1.2ScopeThis report is generally limi
28、ted to piers of 30 in. (760 mm) or larger diameter, made by open or slurry stabilized construction methods. A 30 in. (760 mm) diameter boundary is an arbitrary size. Although smaller-diameter drilled piers have been designed and installed in accordance with this report, it is difficult to detect sid
29、ewall collapse. Refer to ACI 543R for concrete piles having diameters smaller than 30 in. (760 mm), piles installed by the use of hollow stem augers, or other pile types. Also beyond the scope of this report are rectangular columns on spread footings in deep excava-tions and foundations constructed
30、without excavations by methods such as mortar intrusion or mixed-in-place.Piers installed by tapping or ramming concrete or aggre-gate into an excavated shaft are beyond the scope of this report. Engineers and contractors have used the terms “cais-sons,” “foundation piers,” “bored piles,” “drilled s
31、hafts,” and “drilled piers” interchangeably. The term “drilled pier” is used in this report. A drilled pier with an enlarged base can be called a belled caisson, belled pier, or drilled and under-reamed footing. Drilled pier foundations excavated and concreted with water or slurry in the hole have b
32、een called slurry shafts, piers installed by wet-hole methods, or piers installed by slurry displacement methods.CHAPTER 2NOTATION AND DEFINITIONS2.1NotationAb= pier base area, in.2(mm2)Ap= pier shaft surface area, in.2(mm2)D = dead load, lb (N)Dg= dead loads from the supported structure and weight
33、of the pier (gross weight of the pier), lb (N)d = diameter of pier, in. (mm)E = earthquake load, lb (N)Ec= modulus of elasticity, psi (MPa)F = vertical load, lb (N)FS = allowable strength design safety factorFS1= allowable strength design safety factor for bearing resistanceFS2= allowable strength d
34、esign safety factor for side resistancefp= average side resistance, ton/ft2(kPa)fz= unit load transfer from shaft to ground at depth z, ton/ft2(kPa)Hg= horizontal shear at ground surface, lb (N)I = moment of inertia, in.4(mm4)ks= modulus of horizontal soil beam reaction, psi (MPa)L = live load, lb (
35、N)Mg= moment at ground surface, usually applied to pier by superstructure, in.-lb (N-mm)N = number of blows in a standard penetration testPan= anchorage resistance, lb (N)Pq= ultimate end bearing acting at the base, lb (N)Pup= uplift force, lb (N)p = subgrade resistance per unit length along the pie
36、r, lb/in. (N/mm)p-y = lateral load deflection curve at an element of pier, lb/in., in. (N/mm, mm)Q = ultimate axial capacity, tons (kN)qb= unit end-bearing pressure, ton/ft2(kPa)Sn= force from side friction, lb (N)Sp= positive side resistance, lb (N)Sp1= positive side resistance, acting upward on th
37、e pier; normally caused by downward movement of the pier relative to surrounding soil, lb (N)T = relative stiffness factorW = wind load, lb (N)wb= movement of the pier at depth z, in. (mm)wz= unit deflection corresponding to fz, in. (mm)y = lateral deflection of pier, in. (mm)2.2DefinitionsACI provi
38、des a comprehensive list of definitions through an online resource, “ACI Concrete Terminology,” http:/concrete.org/Tools/ConcreteTerminology.aspx. Definitions provided here complement that source.bearing-type piera pier that receives its principal vertical capacity from a subgrade layer at the botto
39、m of the pier.bellan enlargement at the pier bottom to spread the load over a larger area, or to engage additional subgrade mass for uplift loading conditions; also called under-ream.capan upper pier termination, usually placed sepa-rately, to correct deviations from desired location, facilitate anc
40、hor bolt or dowel setting within acceptable tolerances, or combine two or more piers into a unit supporting a column.casinga protective temporary or permanent steel tube, usually cylindrical in shape, lowered into the excavated hole American Concrete Institute Copyrighted Material www.concrete.org2
41、REPORT ON DESIGN AND CONSTRUCTION OF DRILLED PIERS (ACI 336.3R-14)to protect personnel from sidewall collapse or cave-in, or to exclude soil, water, or both from the bination bearing- and side-resistance piera pier that receives its vertical capacity from bearing at the bottom and resistance develop
42、ed along the shaft sides.construction geotechnical engineera geotechnical engi-neer with experience in drilled pier construction who is desig-nated by the owner to carry out the responsibilities defined in this report; also known as a soils engineer, soils and founda-tion engineer, or earthwork and
43、foundation engineer.construction geotechnical engineeringthe interpre-tation and assessment of drilled pier construction observa-tions, equipment and materials used therein, and the field testing and results necessary to permit the construction geotechnical engineer to render a professional opinion
44、as to conformance with the contract documents and founda-tion design. Construction geotechnical engineering does not include drilled pier contractor direction or supervision.drilled pierconcrete cast-in-place foundation element with or without casing that may have an enlarged bearing area and that e
45、xtends downward through weaker soils, water, or both, to a subgrade stratum capable of supporting the loads imposed on or within it.flexible piera pier with a length-to-diameter ratio that will allow flexural deformations from lateral loads; the theo-retical point of fixity is within the pier shaft.
46、geotechnical engineeran engineer with experience in geotechnical investigations for, and the design of, drilled piers who is designated by the owner to prepare the design geotechnical report and work with the structural engineer on the drilled pier design.headtop of pier.Kelly bardrill stem used to
47、advance pier excavation tools.obstructionunderground material that prevents a drill rig from advancing the pier excavation to the desired final bearing level; may be concrete, concrete pipe, rubble, wood, or a boulder that is not part of the parent bedrock.piga disposable device inserted into a trem
48、ie or pump pipe to separate the concrete from the pier excavation fluid inside the pipe. Also called rabbit, rabbit plug.project specificationsthe specifications stipulated by contract for a project that should employ ACI 336.1 by refer-ence and that serve as the instrument for defining the manda-to
49、ry and optional selections available under the specification.rigid piera pier with a small depth-to-diameter ratio that will have negligible flexural deformations under lateral load. Lateral movements will be rotational type involving the entire length of the pier.rocka naturally formed mineral formation underlying the site including intact rock and partially weathered and weathered rock that should be defined by the geotechnical engineer for each project.rock socketed piera pier that derives its capacity from
