soils土的抗剪强度.

§5Shearstrengthofsoils/土的抗剪强度•ShearfailureandCoulombCriterion/剪切破坏与库仑定律•Stresslimitequilibrium/土中一点的极限平衡•Sheartest/抗剪强度试验•Stresspath/应力路径•Rheologyandresidualstrength/土的流变与残余强度5.1ShearfailureandCoulombCriterion剪切破坏与库仑定律SlopesinHighway5.1.1Shearfailureofsoils/土的剪切破坏τ=sτ=τf5.1.2DirectsheartestandCoulombCriterion/直剪试验与库仑定律Shearboxonsand/砂土直剪试验tgftgf←Returnc-cohension（粘聚力）kPaφ-frictionangle,angleofshearingresistance（内摩擦角）(OnNon-cohesivesoils/无粘性土)ctgf(OnCohesivesoils/粘性土)5.2Stresslimitequilibrium/土中一点的应力极限平衡5.2.1MohrStresscircle/莫尔应力圆231223121212cos2sin212sin2cos2121xzxxzxzxa231223121212cos2sin212sin2cos2121xzxxzxzxa231223121212cos2sin212sin2cos2121xzxxzxzxa231223121212cos2sin212sin2cos2121xzxxzxzxa231223121212222221xzxazxazxxatg2202231221xzxzx2cos2sin212sin2cos2121xzxxzxzxasin212cos21213131315.2.2Pole(Originofplane/极点)5.2.3Stresslimitequilibrium(Mohr-CoulombFailureCriterion)土的极限[平衡条件（莫尔——库仑准则）•LimitStressCircleforNon-Cohesive/无粘性土的极限应力圆313122sinooao245245213231tgortg245245245245cos245sin2245cos245sin2sin90sinsin90sinsin1sin12tgtgctgsin1sin113•LimitStressCircleforCohesiveSoils粘性土的极限应力圆245245245245cos245sin2245cos245sin2sin90sinsin90sinsin1sin12tgtgctg24522452452245213231tgctgortgctgiiiiippppp2sin31313111sin1cos2sin1sin113c245245cos245sin2245cos245sin2sin90sin90sinsin1costg←Return5.3ShearTest/抗剪强度试验•Unconfinedcompressiontest/无侧限抗压强度试验2452tgcqu245cr2uuuqcForsoftclay,φisconsideredas0,对饱和的软粘土，φ=0无侧限抗压强度试验原理•Triaxialtest/三轴剪切试验三轴剪切试验原理TotalStressCircle总应力圆EffectiveStressCircle有效应力圆typestest-UU(Unconsolidatedundrainedtest不固结不排水剪——快剪)-CU(consolidatedundrainedtest固结不排水剪——固结快剪)-CD(consolidateddrainedtest固结排水剪——慢剪)(a)SaturatedSoil(b)UnSaturatedSoilUU(Unconsolidatedundrainedtest/不固结不排水剪)-CU(consolidatedundrainedtest/固结不排水剪)-CD(consolidateddrainedtest/固结排水剪)UUCUCD)32(22rHrMS•InsituVanetest/十字板剪切试验←Return5.4StressPath/应力路径'cos''coscacactgactgctgSinNormallyconsolidatedsoilsOverconsolidatedsoils正常固结土超固结土