1、5 Shear strength of soils/土的抗剪强度 Shear failure and Coulomb Criterion/剪切破坏与库仑定律 Stress limit equilibrium/土中一点的极限平衡 Shear test/抗剪强度试验 Stress path/应力路径 Rheology and residual strength/土的流变与残余强度5.1Shear failure and Coulomb Criterion剪切破坏与库仑定律Slopes in Highway5.1.1 Shear failure of soils/土的剪切破坏=s=f5.1.2 Di
2、rect shear test and Coulomb Criterion/直剪试验与库仑定律Shear box on sand/砂土直剪试验tgftgfReturnc-cohension（粘聚力）kPa-friction angle,angle of shearing resistance（内摩擦角）(On Non-cohesive soils/无粘性土)ctgf(On Cohesive soils/粘性土)5.2 Stress limit equilibrium/土中一点的应力极限平衡5.2.1 Mohr Stress circle/莫尔应力圆231223121212cos2sin212s
3、in2cos2121xzxxzxzxa231223121212cos2sin212sin2cos2121xzxxzxzxa231223121212cos2sin212sin2cos2121xzxxzxzxa231223121212cos2sin212sin2cos2121xzxxzxzxa231223121212222221xzxazxazxxatg2202231221xzxzx2cos2sin212sin2cos2121xzxxzxzxasin212cos21213131315.2.2 Pole(Origin of plane/极点)5.2.3 Stress limit equilibriu
4、m(Mohr-Coulomb Failure Criterion)土的极限平衡条件（莫尔库仑准则）Limit Stress Circle for Non-Cohesive/无粘性土的极限应力圆313122sinooao245245213231tgortg245245245245cos245sin2245cos245sin2sin90sinsin90sinsin1sin12tgtgctgsin1sin113Limit Stress Circle for Cohesive Soils粘性土的极限应力圆245245245245cos245sin2245cos245sin2sin90sinsin90s
5、insin1sin12tgtgctg24522452452245213231tgctgortgctg iiiiippppp2sin31313111sin1cos2sin1sin113c245245cos245sin2245cos245sin2sin90sin90sinsin1costgReturn5.3 Shear Test/抗剪强度试验Unconfined compression test/无侧限抗压强度试验2452tgcqu245cr2uuuqc For soft clay,is considered as 0,对饱和的软粘土，=0无侧限抗压强度试验原理Triaxial test/三轴剪切
6、试验三轴剪切试验原理vTotal Stress Circle 总应力圆vEffective Stress Circle 有效应力圆vtypes test-UU(Unconsolidated undrained test 不固结不排水剪快剪快剪)-CU(consolidated undrained test 固结不排水剪固结快剪固结快剪)-CD(consolidated drained test 固结排水剪慢剪慢剪)(a)Saturated Soil (b)Un Saturated Soil UU(Unconsolidated undrained test/不固结不排水剪)-CU(consolidated undrained test/固结不排水剪)-CD(consolidated drained test/固结排水剪)UU CU CD)32(22rHrMSIn situ Vane test/十字板剪切试验Return5.4 Stress Path/应力路径coscoscacactgactgctgSinNormally consolidated soils Over consolidated soils正常固结土 超固结土
