粗粒土等压固结与K_(0)固结三轴试验对比研究

Comparison of Isotropic Consolidation and K_(0)Consolidation Large Triaxial Tests of Coarse-Grained Soil

对不同密度砂卵石料进行等压固结和K_(0)固结条件下的排水剪切试验,并分析固结应力条件对砂卵石料强度和应力—应变特性的影响。结果表明,峰值偏应力与高围压下密实土体结构改变有关,干密度较小时K_(0)固结条件下的试验值较大;干密度较大而围压较小时,K_(0)固结条件下的试验值较大;干密度和围压均较大时,等压条件下的试验值较大。两种固结条件下的应力应变特征相似,随试样密度的增大由应变硬化向应变软化过渡,但K_(0)固结条件下试样剪胀性更加明显,两种固结条件下试样所得的邓肯-张模型、南水双屈服面模型参数相近,说明采用等压固结排水剪切试验确定深厚覆盖层坝基相关模型参数是可行的。

Consolidated drained(CD)shear texts are conducted under isotropic consolidation and K_(0)consolidation on sand and pebble materials of different densities to analyze the influence of consolidation stress conditions on the strength and stressstrain characteristics of the materials.The results indicate that for the peak deviator stress,the test values are higher under K_(0)consolidation conditions when the dry density is low.When the dry density is high and the confining pressure is low,the test values are also higher under K_(0)consolidation conditions.However,when both dry density and confining pressure are high,the test values are higher under isotropic conditions,which is related to the structural changes of dense soil under high confining pressure.The stress-strain characteristics are similar under both consolidation conditions,with a transition from strain hardening to strain softening as the density of specimen increases.However,the dilatancy of the specimen under K_(0)consolidation condition is more obvious.The parameters of the Duncan-Chang model and Shen’s elastoplastic model obtained under both consolidation conditions are similar,indicating that it is feasible to use the isotropic consolidation drainage shear test to determine the relevant model parameters for deep overburden dam foundation.