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Technical Notebook
WATERPROOFING STRUCTURES INSTALLED BELOW GROUND LEVEL
C.P. MK 83
8730
- (GB) 04/11
Technical Notebook
WATERPROOFING STRUCTURES INSTALLED BELOW GROUND LEVEL
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Technical Notebook
WATERPROOFING STRUCTURESINSTALLED BELOW GROUND LEVEL
page 04 1. INTRODUCTION
page 05 2. GEOTECHNICSANDFOUNDATIONSpage 05 2.1 GEOTECHNICS
page 06 2.2 FOUNDATIONS
page 11 3. HYDROLOGYANDHYDROGEOLOGYpage 12 3.1 THEWATER-GROUNDRELATIONSHIP
page 12 3.2 WATERANDSUBSOIL
page 14 3.3 DRAINAGESYSTEMS
page 20 4. EXCAVATIONWORK
page 24 5. MAPEIWATERPROOFINGSYSTEMSFOR FOUNDATIONSTRUCTURESpage 24 5.1 WHYWATERPROOF?
page 26 5.2 MAPEPROOFANDBENTONITE
page 29 6. SPECIFICATIONSFORFOUNDATION CONCRETE
page 32 7. WATERPROOFINGNEWSTRUCTURES BELOWGROUNDLEVELpage 34 7.1 SEALINGCONSTRUCTIONJOINTS
page 34 7.2 WATERPROOFINGTHEBASEOFAJIBCRANE
page 35 7.3 WATERPROOFINGALIFTWELL
page 40 7.4 WATERPROOFINGHORIZONTALFOUNDATIONPADS
page 42 7.5 WATERPROOFINGPILEHEADS
page 47 7.6 WATERPROOFINGVERTICALSURFACESBEFORECASTING
page 54 7.7 WATERPROOFINGVERTICALSURFACESAFTERCASTING
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Technical Notebook
WATERPROOFING STRUCTURESINSTALLED BELOW GROUND LEVEL
page 55 7.7.1 WATERPROOFINGVERTICALSURFACESAFTER CASTINGWITHMAPEPROOFORMAPEPROOFLW
page 56 7.7.2 WATERPROOFINGVERTICALSURFACESAFTER CASTINGWITHMAPELASTICFOUNDATION
page 58 7.7.3 WATERPROOFINGVERTICALSURFACESAFTER CASTINGWITHPRODUCTSFROMTHEPLASTIMUL RANGE
page 61 7.8 WATERPROOFINGSTRUCTURALJOINTS
page 64 7.9 SEALINGTHROUGH-PIPESINVERTICALWALLS ANDFOUNDATIONPADS
page 66 7.10 SEALINGADRAINAGEWELL
page 67 7.11 WATERPROOFINGACCESSRAMPSTOAREAS BELOWGROUNDLEVEL
page 69 7.12 WATERPROOFINGDEPURATIONTANKS
page 71 7.13 WATERPROOFINGASEWAGEWASTEOUTLET ANDVENTCASTINPLACE
page 74 7.14 WATERPROOFINGCONSTRUCTIONSBUILTUSING THETOP-DOWNMETHOD
page 77 8. WATERPROOFINGEXISTING STRUCTURESBELOWGROUNDLEVELpage 78 8.1 LININGSURFACESINROOMSBELOWGROUNDLEVEL
page 78 8.1.1 WATERPROOFINGVERTICALSURFACES
page 80 8.1.2 WATERPROOFINGHORIZONTALANDVERTICAL SURFACESWITHMAPEPROOF
page 84 8.1.3 WATERPROOFINGHORIZONTALANDVERTICAL SURFACESWITHACOMBINEDBENTONITE- CEMENTITIOUSSYSTEM
page 89 8.2 WATERPROOFINGALIFTWELLAGAINST HYDRAULICLIFT
page 90 8.2.1 WATERPROOFINGWITHOSMOTICMORTAR
page 91 8.2.2 WATERPROOFINGWITHACOMBINEDOSMOTIC MORTAR-FLEXIBLECEMENTITIOUSMORTARSYSTEM
page 92 8.2.3 WATERPROOFINGWITHACOMBINEDBENTONITE- FLEXIBLECEMENTITIOUSMORTARSYSTEM
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2. GEOTECHNICS AND FOUNDATIONS
2.1 GEOTECHNICSGeotechnics is thestudyof themechanicalaspectsof thegroundand
itsapplication inengineeringworks.Thestratographicconformationof
thegroundanditsmechanicalbehaviourisanalysedtoidentifythemost
suitabletypeoffoundationstoguaranteethestabilityanddurabilityofa
structure.
Foundations are structural elements with the function of transferring
stressesand loads,bothpermanentandaccidental, fromthestructure
constructedonthefoundationstotheground.Thetypeof foundations
determines the footprint that a structure leaves on the ground. The
sizeofthefootprint(plinths,groundbeams,foundationpadsandribbed
foundationpads)isinverselyproportionaltotheresistanceoftheground
and proportional to the loads to be discharged onto it. The ground,
foundationsandtheoverallstructure,therefore,formasingleunitbody
whichmustbeconsideredasasinglesystem.
Thedesignofastructurestartswithapreliminaryanalysistodetermine
the type, stratographic conformation and physical and mechanical
characteristics of the ground. It is particularly important to determine
the safety load of the ground, known as its load-bearing capacity,
expressedinkg/cm2.
Apartfromtheeconomicaspectstobetakenintoconsideration,thereare
anumberofotherparameterswhichalsocontributeindefiningthetype
offoundationstouse,withthemainonesbeingasfollows:
the construction system adopted for the structure built on the
foundations;
restraintsandguidelinesoflocalbuildingregulations;
thedepthatwhichthelayerwithsufficientload-bearingcapacityon
whichtheloadsactislocated.
1. INTRODUCTIONThe issuesdealtwith in thismanual regardwaterproofingmethods for
various types of structures below ground level (Fig. 1.1) according to
the type of ground and obviously the effect of water acting upon the
structure.Athoroughanalysisofthemorphologicalcharacteristicsofthe
groundandwaterflowduringvariousperiodsoftheyearallowforcorrect
analysisoftheconstructiontechniqueappliedforstructuresbelowground
level.Studying thecharacteristicsof theground (geotechnics)supplies
useful informationabout the load-bearingcapacityof theground itself
anditshydrogeologicalconformation.Itisalsoimportantthatanywater
present below ground level is carefully studied (hydrology) in order to
assessthecontextinwhichnewstructuresarebuilt,suchaswaterunder
pressure,waterpercolating frombelowor thepresenceofwidespread
damp. Thiswill then influence the type of foundations system chosen
forthestructure,thetypeofwaterproofingusedand,clearly,thetypeof
temporarysupportsrequiredtoconstructthefinalstructure.
Fig.1.1Phasesofanexcavationforconstructionworkcarriedoutbelowgroundlevelinabuilt-uparea
Technical Notebook
WATERPROOFING STRUCTURESINSTALLED BELOW GROUND LEVEL
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Fig.2.2-Truncated-pyramidplinth
Fig.2.1Classificationoffoundationsaccordingtotheirloadtransfermechanismtotheground
2.2 FOUNDATIONSFoundations forma groupof structural elementswithin a construction
system,withthefunctionoftransmittingloadstotheground.Sincethe
behaviouroftheground,thefoundationsandthestructurebuiltonthe
foundationsaredependentoneachother,thereisawidearrayofvariables
whichhave tobeconsideredwhencalculating thesizeof foundations.
Theparametersbelowmustbetakenintoconsiderationwhenchoosing
thetypeoffoundations:
theloadsactinguponthefoundations;
thefinaluseofthebuilding;
typeandstratographicconformationoftheground;
thepresenceandlevelofthestratum;
theheightofthefoundations;
economicimplications;
presenceandtypeofsurroundingbuildings;
frictionandslopeofthegroundonwhichthefoundationsareinstalled.
Theforcestransmittedfromthestructuretothefoundationsarethesum
ofthefollowing:
loadsfromthestructure;
permanentoverloads;
accidentaloverloads(accordingtothefinaluseofthestructure);
horizontalforcesduetowinds(generallybendingmoments);
horizontalseismicloads(appliedeitherdynamicallyorstaticallytothecalculationmodel).
Foundationsmaybesub-dividedaccordingtotheirloadtransfermechanism
tothegroundoraccordingtotheTerzaghiclassificationsystem.Inthefirst
case,thefoundationsmaybeclassifiedasillustratedinFig.2.1.
With direct (or surface) foundations, the forces are transferred to the
groundbyenlarging the load-bearingelementsof the structureon the
foundations, while with indirect (or deep) foundations, the forces are
transferredmainlybyfrictionorlateraladhesionatthepile-groundinterface.
Themostsimpleformofintermittentdirectfoundationsarerepresented
by plinths,which basically consist of enlarging the pillars to distribute
the loads over a larger surface area. In certain cases, because of the
poor mechanical characteristics of the ground, restraints by seismic
regulationsor if the loadshave tobedistributedover largerareasand
theplinthsaretoolarge,foundationpadswhichcovertheentireareaof
thebuilding(continuousdirectfoundations)areamorefeasiblesolution.
Inothercases,indirectfoundationssuchaspileshavetobeused,sothat
theloadsfromthestructureonthefoundationsaretransferredtomore
compactandresistantgroundwhichmayonlybefounddeeperdown.
If theTerzaghiclassification is followed,ontheotherhand, thevarious
typesoffoundationsmaybesub-dividedaccordingtotheratioD/B(D:
depthofthefoundations,B:widthofthefoundationbase):
directorsurfacefoundations(plinths,continuousbeams,foundationpads)D/B