Testing Study On Dynamic Properties Of Dongshan Loess In Taiyuan

Dynamic properties of Dongshan loess in Taiyuan are studied .through laboratory.dynamic triaxial tests; and variations with water contents are discussed of its dynamic parameters, dynamic shear strength and dynamic subsidence. Besides, other, laws are also discussed. Test results show that water content has a major influence on the dynamic properties of Taiyuan loess. For unsaturated intact loess, it is undoubtedly correct that the influence of water content is of the first importance on the study of its dynamic properties.The general tendency is that dynamic parameters and dynamic shear strength decrease with an increase of water content, but increase with an increase of consolidation pressure. Dynamic subsidence goes by contraries. Variation of dumping ratio with water content is not obvious; and the value range is generally from 0 to 0.05, with a maximum value smaller than 0.2. Little influence has variation of water content on dynamic friction angle.Other conditions being constant, secant dynamic elastic modulus, maximum secant dynamic elastic modulus, dynamic failurestress, dynamic cohesion or dynamic critical stress decrease with anincrease of water content, while dynamic subsidence increase with an increase of water content. When taking plastic limit as a bound, variation of water content smaller, than plastic limit has major influence on secant dynamic elastic modulus, maximum secant dynamic elastic modulus, dynamic failure stress, dynamic cohesion or dynamic critical stress; while variation of water content greater than plastic limit has very minor influence on them.Other conditions being constant, Secant dynamic elastic modulus, maximum secant dynamic elastic modulus, dynamic failure stress or dynamic critical stress increase with an increase of consolidation pressure.Structure of loess is not to be ignored as for its influence on the maximum secant dynamic elastic modulus, according to the analysis of normalized relation between maximum secant dynamic elastic modules and water contents. Taiyuan loess with water content smaller than 5% can be classified into non-dynamic-subsidence loess, and that greater than 5% can be classified into dynamic-subsidence loess. 'Dynamic subsidence rate' defined in this thesis refers to an increment of residual strain caused by a unit increment of dynamic stress, and can quantitatively express the intensity of dynamic subsidence for loess samples prior to failure. The larger the dynamic subsidence rate, the more intense the dynamic subsidence is. The variation of the dynamic subsidence rate is that when reaching dynamic critical stress, the larger the water content or the smaller the consolidation pressure, the larger the dynamic subsidence rate is.