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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