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Fig.1.Diagramofananchor-reinforcedslope.(a)Slopewithnormalstressesontheslipsurfaceinducedbyself-weightandanchorloads,respectively.(b)Geometryforcomputingnormalstressesontheslipsurfacepurelyinducedbyananchor

load.

[2a]

β=

β1+β2

2

[2b]

θ=θ′+β2

β1+β2β β2

2=θ′ 1

2[2c]ω=θ′ θ i=

β1 β2

2

iThus[3a]

PH=Pcosω=Pcos β β

2 i

[3b]

PV= Psinω= Psin β 1 β22

i

Substitutingeqs.[3a]and[3b]intoeq.[1a]gives

Can.Geotech.J.Vol.42,

2005

Fig.2.Stressdistributioninawedgewithconcentratedforcesatitsapex.

σ β1 β2 i cos θ′ β1 β2

[4]

r=

2Pcosr 2 2

β1+β2+sin(β1+β2)

sin β β2 β β2

12i sin θ′ 12

β 1+β2 sin(β1+β2)

Thecircumferentialandshearstressesarestillzero.

Thenormalstressσpontheslipsurfacewithaninclina-tionofαtothehorizontalisobtainedfromstaticanalysisas[5]

σp=σrsin2(θ′+α)

Ifmorethanoneanchorloadisactingontheslope,σtheirindividualcontributions.

pistakenasthesumofUsually,theprestressingofananchorisaccomplishedoverashortduration,andsomecohesivesoilsare,tosomedegree,inanundrainedcondition.Thiswillleadtoachangeinpore-waterpressure( u)withintheslidingmass.Accord-ingtoSkempton(1954), uisrelatedtochangesintheprin-cipalstressesinthesoilbythefollowingrelationship:[6]

u=B[ σ3+A( σ1– σ3)]

where σAandBareporepressureparameters;and σmajorandminorprincipalstresses1and3arechangesinre-spectively.

TheporepressureparametersAandBcandeterminedbylaboratorytests.Forsaturatedsoils,Bapproachesunity.ThevalueofAvarieswiththedegreeofoverconsolidationofthesoil,beingpositivefornormallyconsolidatedsoils(intherangeof0.5–1.0),andincontrast,beingnegativeforheavilyconsolidatedsoils(intherangeof–0.5to0.0).