STRESS-HISTORY EFFECTS ON SHEAR MODULUS OF SOILS
STRESS-HISTORY EFFECTS ON SHEAR MODULUS OF SOILS
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应力历史对土壤剪切模量的影响
DOI：
10.3208/sandf1972.13.77
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发表时间：
1973
影响因子：
3.7
通讯作者：
F. E. Richart
中科院分区：
文献类型：
--
作者：
S. S. Afifi;F. E. Richart
通过土样的共振柱试验，研究了围压持续时间和应力历史模式的影响。对于每种土，在小剪切应变幅下获得的动态剪切模量是随着测试条件的改变而评估的量。在均匀围压下，在施加约1000分钟的压力后，剪切模量发生增加，其与对数时间近似呈线性关系。每对数循环的剪切模量增加速率表示为1000分钟时剪切模量数值的百分比，以使每次测试的压力大小的影响最小化。对于中值粒径大于0.04 mm的土壤，每对数周期剪切模量的增加百分比约为3%或更少。对于干燥和饱和的高岭石样品，这种增加平均约为6%至13%。超固结的影响是稍微降低这种速率的剪切模量增加每log cycle.土的中值粒径为0.04 mm或更大的表现出小幅度的剪切模量的变化不大，作为施加围压的时间增加，或以前的预固结的影响不大。对于较细的土壤（D50 ~ 0.04 mm），加载时间和预固结的影响是显着的。因此，细粒土的实验室剪切模量外推到现场应用需要仔细研究。
The effects of time duration of the confining pressure and stress-history patterns were studied through resonant column tests of soil samples. For each soil the dynamic shear modulus obtained at small shearing strain amplitudes was the quantity evaluated as the testing conditions were changed.Under uniform confining pressures an increase in shear modulus occurred which was approximately linear with log time after about 1000 minutes of pressure application. This rate of shear modulus increase per log cycle was expressed as a per cent of the numerical value of the shear modulus at 1000 minutes, to minimize the influence of the pressure magnitude for each test. For soils with median grain size larger than about 0.04 mm the per cent increase in shear modulus per log cycle was about 3% or less. For dry and saturated samples of kaolinite, this increase averaged about 6% to 13%. The effect of overconsolidation was to reduce slightly this rate of shear modulus increase per log cycle.Soils with median grain size of 0.04 mm or greater showed little change in the small amplitude shear modulus as the time of applied confining pressure increased, or little influence of previous preconsolidation. For finer soils (D50«0.04 mm) the effects of time of loading and of preconsolidation were significant. Consequently, extrapolation of laboratory shear moduli of fine-grained soil to field applications requires careful study.