1、 American Society of Civil EngineersDesign and Construction of Frost-Protected Shallow FoundationsThis document uses both Systme International (SI) and customary units.SEI/ASCE 32-01Published by the American Society of Civil Engineers1801 Alexander Bell DriveReston, Virginia 20191-4400ABSTRACTThis s
2、tandard addresses the design and construction of frost-pro-tected shallow foundations in areas subject to seasonal ground freez-ing. Foundation insulation requirements to protect heated and un-heated buildings from frost heave are presented in easy-to-followsteps with reference to design tables, cli
3、mate maps, and other neces-sary data to furnish a complete frost-protection design. The advan-tages of this technology include improved construction efficiencyover conventional practices, increased energy efficiency, minimizedsite disturbance, and enhanced frost protection. A commentary is in-cluded
4、 to provide background information and important technicalinsights.Library of Congress Cataloging-in-Publication DataDesign and construction of frost-protected shallowfoundations/American Society of Civil Engineers.p. cm.(ASCE standard)“ASCE 32-01.”Includes bibliographical references and index.ISBN
5、0-7844-0564-61. FoundationsDesign and constructionStandardsCold regions. 2. FoundationsCold weather conditions. 3.Frozen ground. I. American Society of Civil Engineers.TH2101 .D44 2001624.15dc21 2001034096The material presented in this publication has been prepared in ac-cordance with generally reco
6、gnized engineering principles and prac-tices, and is for general information only. This information shouldnot be used without first securing competent advice with respect toits suitability for any general or specific application.The contents of this publication are not intended to be and should notb
7、e construed to be a standard of the American Society of Civil En-gineers (ASCE) and are not intended for use as a reference in pur-chase of specifications, contracts, regulations, statutes, or any otherlegal document.No reference made in this publication to any specific method, prod-uct, process, or
8、 service constitutes or implies an endorsement, rec-ommendation, or warranty thereof by ASCE.ASCE makes no representation or warranty of any kind, whether ex-press or implied, concerning the accuracy, completeness, suitability,or utility of any information, apparatus, product, or process dis-cussed
9、in this publication, and assumes no liability therefore.Anyone utilizing this information assumes all liability arising fromsuch use, including but not limited to infringement of any patent orpatents.ASCE and American Society of Civil EngineersRegistered in U.S.Patent and Trademark Office.Photocopie
10、s: Authorization to photocopy material for internal orpersonal use under circumstances not falling within the fair use pro-visions of the Copyright Act is granted by ASCE to libraries andother users registered with the Copyright Clearance Center (CCC)Transactional Reporting Service, provided that th
11、e base fee of $8.00per chapter plus $.50 per page is paid directly to CCC, 222 Rose-wood Drive, Danvers, MA 01923. The identification for ASCEBooks is 0-7844-0564-6/01/$8.00 H11001 $.50 per page. Requests forspecial permission or bulk copying should be addressed to Permis-sions a 100-yearmean return
12、 period occurs in 1% of the years (1/100),has a 1% annual probability of exceedance, or is ex-ceeded once every 100 years on average.Mean Annual Air Temperature (MAT): The av-erage of all daily average outdoor air temperatures(minimum plus maximum daily temperature dividedby two) in one or more year
13、s.Mean Return Period (Mean Recurrence Inter-val): A probability estimate of the average number ofyears between which an event of a given magnitudewill be equaled or exceeded (1/p, where p is the proba-bility of an event happening over a specified period).NonFrost-Susceptible Soil: A soil that does n
14、otdisplay significant detrimental ice segregation (i.e., icelens development) during freezing. Generally, granularsoils with less than 6% by mass passing a #200 sieve(0.074 mm) have low frost susceptibility, whereas siltsand clays or sands and gravels (i.e., granular soils)with high fines content ge
15、nerally have medium to highfrost susceptibility.DESIGN AND CONSTRUCTION OF FROST-PROTECTED SHALLOW FOUNDATIONS2TABLE 2. Symbols and UnitsSymbol Description SI Units English UnitsDhWidth of horizontal wing insulation along walls m ft or inDhcWidth of horizontal wing insulation at corners m ft or inDg
16、Width of ground insulation beyond the perimeter of an unheated building m ft or inF100100-year mean return period AFI H11034 C-hr H11034 F-daysh Floor height above finished grade m ft or inhf, hfcFoundation depth along walls or at corners m ft or inhvDepth of vertical wall insulation into ground (mi
17、nimum footing depth) m ft or inL1, L2, L3Length of unheated portion of otherwise heated building m ft or inLcLength (along a wall) of corner insulation m ft or inMAT Mean annual air temperature H11034 C H11034 FRfR-value of floor/slab construction or assembly m2-H11034 K/W hr-ft2-H11034 F/BtuRvRequi
18、red R-value of vertical wall insulation m2-H11034 K/W hr-ft2-H11034 F/BtuRhRequired R-value of horizontal wing insulation m2-H11034 K/W hr-ft2-H11034 F/BtuRhcRequired R-value of horizontal wing insulation at corner m2-H11034 K/W hr-ft2-H11034 F/BtuRgRequired R-value of ground insulation for unheated
19、 buildings m2-H11034 K/W hr-ft2-H11034 F/BtuReffEffective R-value (thermal resistance) of an insulation material in service conditions m2-H11034 K/W hr-ft2-H11034 F/BtureffEffective resistivity (Reffper inch) of an insulation material in service conditions m-H11034 K/W hr-ft2-H11034 F/Btu-inTABLE 3.
20、 Unit ConversionsLength 1 m H11005 100 cm H11005 3.28 ft H11005 39.4 inMass 1 kg H11005 2.2 lbm (0.0683 slugs)Weight 1 N H11005 0.225 lbfArea 1 m2H11005 10,000 cm2H11005 10.8 ft2H11005 1550 in2Volume 1 m3H11005 1 H11003 106cm3H11005 35.3 ft3H11005 6.1 H11003 104in3Density 1 kg/m3H11005 0.0624 lbm/ft
21、3(pcf)Pressure 1 kPa H11005 0.145 lbf/in2(psi)H11005 20.8 lbf/ft2(psf)Temperature H11034 F H11005 1.8 (H11034C H11001 32)Freezing index 1H11034 C-hr H11005 0.075 H11034 F-daysThermal properties: resistance 1 m2-H11034 K/W H11005 5.68 hr ft2-H11034 F/BtuR-value resistivity 1 m-H11034 K/W H11005 0.144
22、 hr ft2-H11034F/(Btu . in) R/inPermafrost: Soil that, in its natural state, remainsfrozen throughout the year. Generally occurs in regionswhere the mean annual soil surface temperature is be-low freezing.R-Value (Thermal Resistance): A measure of theability to retard heat flow for a given thickness
23、(hr H11080 ft2H11080 F/Btu)m2H11080 K/W). It is calculated by di-viding the materials thickness by its thermal conduc-tivity. The thermal resistance of material assembled inlayers is calculated by summing the thermal resistancesof the individual components.Suspended Floor: A floor not directly suppo
24、rtedby the earth, such as a floor over a basement orcrawlspace.Thermal Resistivity: The insulative capability ofa material to retard heat flow for a unit thickness of ho-mogeneous material over a unit area, commonly givenas R per inch.Vertical Insulation: Insulation placed verticallyagainst the exte
25、rior perimeter surface of the foundation.Wing (Horizontal) Insulation: Insulation placedin a horizontal position or sloped downward and awayfrom exterior walls of a foundation (abuts the verticalfoundation wall insulation).4. DESIGN PRINCIPLES4.1 GENERALIn regions of seasonal ground freezing, shallo
26、wfoundations not extending below the design frost depthshall be protected against frost heave by one or moreof the following methods:1. use of nonfrost-susceptible layers of undisturbedground or fill materials (Section 4.2);2. insulation of foundations to mitigate frost penetra-tion and effects of f
27、rost heave (Section 4.3); or3. approved design and details supported by engineer-ing analysis.4.1.1 Bearing CapacityThe allowable bearing capacity of the undisturbedsoil, fill materials, or insulating materials supportingthe foundation shall be equal to or greater than thestructural loads imposed by
28、 the building in accordancewith the local building code or engineering analysis.The foundation depth, as measured from finished gradeto bottom of footing, shall be the greater of that re-quired by this Standard or that required for adequatebearing capacity on soil or fill. The foundation depth,as me
29、asured from finished grade to bottom of footing,shall not be less than 12 inches (0.3 m).4.1.2 DrainageThe site shall be graded to drain surface wateraway from foundation walls, in accordance with localbuilding code provisions or approved practice. In soilsother than GW, GP, SW, SP, GM, and SM (Unif
30、iedSoil Classification System, ASTM D2487), a layer ofscreened and washed gravel or crushed stone shall beplaced beneath the horizontal insulation and drained todaylight, or an approved foundation drainage systemshall be provided.4.1.3 CompactionFill materials shall be placed and compacted in ac-cor
31、dance with an approved design or approved prac-tice. An approved design shall be required for fill ma-terials that support foundation loads and are more than12 inches (0.3 m) thick or vary in thickness by morethan 6 inches (0.15 m).4.1.4 Insulation ProtectionVertical insulation placed externally on
32、foundationwalls or along edges of slab-on-ground floors shallhave an opaque and weather-resistant protective cover-ing to mitigate degradation of thermal performancefrom ultraviolet radiation, physical damage, or othersources of deterioration. Protective coverings or coat-ings shall be compatible wi
33、th the insulation materialand extend a minimum of 6 inches (0.15 m) below fin-ished grade. Polystyrene insulation shall not be ex-posed to petroleum-based products. Horizontal insula-tion placed less than 12 inches (0.3 m) below theground surface, or any portion extending outward morethan 24 inches
34、(0.6 m) from the foundation edge, shallbe protected against damage by concrete or asphaltpavement on the ground surface directly above the in-sulation by cementitious board or plywood rated forbelow-ground use, or by other approved materialsplaced directly on the top surface of the insulation.4.1.5
35、Termite ProtectionBuildings with underground foam insulation ingeographic areas subject to termite infestation withstructural members constructed of materials suscepti-ble to termite damage shall comply with local build-ing code requirements for termites and shall be pro-tected against termite infes
36、tation. Methods ofprotection shall include chemical soil treatment, phys-ical barriers (such as termite shields), or any combi-nation of these methods.SEI/ASCE 32-0134.2 FOUNDATIONS ON NONFROST-SUSCEPTIBLE GROUND OR FILL MATERIALFoundations placed on a layer of well-drained,undisturbed ground or fil
37、l material that is not suscep-tible to frost shall have the thickness of such a layerincluded in meeting the design frost depth defined inSection 3.2. Undisturbed granular soils or fill materialwith less than 6% of mass passing a #200 (0.074mm) mesh sieve in accordance with ASTM D422 andother approv
38、ed nonfrost-susceptible materials shallbe considered nonfrost-susceptible. Classification of frost susceptibility of soil shall be determined by a soils or geotechnical engineer, unless otherwise approved.4.3 FOUNDATIONS WITH INSULATION TOPREVENT GROUND FREEZINGFrost-protected shallow foundations (F
39、PSF) shallbe designed in accordance with the following sectionsof this Standard using the design data from AppendixA: Section 5 Simplified FPSF Design Method forHeated Buildings with Slab-on-GroundFoundations Section 6 FPSF Design Method for Heated Buildings Section 7 FPSF Design Method for Unheated
40、Buildings Section 8 Special Design Conditions for FPSFBuildings with foundations designed in accor-dance with Section 5 or 6 that are not completed andnot heated before the time of first ground freezing shallhave additional temporary ground protection or tempo-rary heating of internal space in accor
41、dance with Table1, or the foundation shall be designed in accordancewith provisions for unheated buildings (Section 7).5. SIMPLIFIED FPSF DESIGN METHOD FOR HEATED BUILDINGS WITH SLAB-ON-GROUND FOUNDATIONSDesigns based on the following simplified proce-dure shall be permitted to be used to specify in
42、sulationfor slab-on-ground foundations of heated buildings, inlieu of the detailed design in Section 6. Design proce-dures of Section 6 shall be used when buildings in-clude suspended floors. Unheated areas, such as at-tached garages, shall be designed in accordance withSection 7, except when design
43、ed in accordance withSection 4.2 or when the foundation of the unheatedarea extends below the design frost depth. Cold-bridges shall be prevented (see Section 8.4).Step 1: Select the Sites Design Air-Freezing In-dex, F100The 100-year mean return period AFI, F100, shallbe selected from Figure A1 or T
44、able A3 of Appendix A.Step 2: Determine Insulation R-Value, Dimen-sions, and Footing DepthUsing F100from Step 1, select vertical and hori-zontal insulation R-values, horizontal insulation dimen-sions, and minimum footing depth from Table 4. Verti-DESIGN AND CONSTRUCTION OF FROST-PROTECTED SHALLOW FO
45、UNDATIONS4TABLE 4. Minimum Insulation Requirements for Frost-Protected Shallow Foundations of Heated Buildings1Horizontal InsulationR-value, RhAir-Freezing Vertical(hr ft2 H11034 F/Btu) Horizontal Insulation Minimum FootingIndex, F100Insulation Along AtDimensions per Figure 1 (in) Depth (in)(H11034
46、F-days) R-value, RvWalls Corners DhDhcLchv500 or less 0 NR NR NR NR NR 121,500 4.5 NR NR NR NR NR 122,000 5.6 NR NR NR NR NR 142,500 6.7 1.7 4.9 12 24 40 163,000 7.8 6.5 8.6 12 24 40 163,500 9.0 8.0 11.2 24 30 60 164,000 10.1 10.5 13.1 24 36 60 164,500 12.0 12.0 15.0 36 48 80 161Insulation requireme
47、nts are for protection against frost damage in heated buildings. Interpolation between values is permissible. For interpolationpurposes, NR H11005 0 (NR H11005 not required).cal and horizontal insulation shall be located on thefoundation in accordance with Figure 1. The insulationshall be placed to
48、prevent cold-bridging between thefoundation wall or other thermally conductive materialsof the building foundation and the adjacent soil or out-side air (see Section 8.4). Horizontal insulation shall bebedded firmly on a smooth ground surface or, where re-quired by Section 4.1.2, a drained granular
49、base. Whenfoundation depths, hv, greater than 12 inches (0.3 m)are required by Table 4, the increase in depth may besatisfied by substituting nonfrost-susceptible fill mate-rials, as defined in Section 4.2. Insulation placed belowthe floor slab shall not exceed a nominal R-value of 10(hr H11080 ft2H11080 F/Btu) 1.76 m2H11080 K/W.Step 3: Select Insulation Types, CalculateThicknesses, and Provide ProtectionAn approved insulation material type shall be se-lected in accordance wi
