Test Research On The Dynamic Characteristic Of Recently Deposited Silt In Handan

In this paper, this paper had a research on dynamic characteristics of recentlydeposited silty soit in Handan by cyclic simple shear system under the equivalentseismic load. Through the experiment of Handan newly deposited silt, the dynamicdeformation and dynamic strength has been studied.Dynamic deformation test is mainly used to determine the cyclic parameters ofrecently deposited silt in Handan: dynamic shear modulus, damping ratio. This paperanalyzed the consolidation of vertical stress and shear stress ratio on the effects ofdynamic shear modulus and damping ratio.At the same time, dynamic strength test analysied of the shear strength of recentlydeposited silt liquefaction in Handan. Using the H.B. Seed theory, I got the initialliquefaction depth of silty soil in Handan, its liquefaction area and influence factors ofburied depth, dynamic load in the test of this area was obtained. Finally, the test resultsof liquefaction were discrimined by using two kinds of methods in current norms ofchina. This paper mainly includes the following contents:(1) Through the dynamic parameter test of silty soil in Handan, dynamic shearmodulus ratio increases with the increase of consolidation pressure, but decreases withthe increase of shear strain; the maximum dynamic shear modulus increases with theincrease of consolidation pressure, and it presents the nonlinear incremental rule; thenonlinear incremental rule; the damping ratio increases with the increase of shear strainbut decreases with the increase of consolidation pressure.(2) Through liquefaction test of silt in Handan, the region is not liquefactoaryabove the underground water level. Otherwise, it is liquefactoary. Critical liquefactiondepth is about2m, the initial liquefaction area is about2-6m below the ground; thedynamic shear stress ratio decreases with increase of vibration cycle times, initialliquefaction vibration frequency decreased gradually with increase of depth; in the cyclenumber and shear stress ratio curve of arbitrary curve, two points are equivalent to eachother.(3) Through the discrimination method and validated in norm, silt in this regionhave liquefaction problems; for the important buildings under the field conditions oflower underground water level and the shallower burial depth, in addition to the provisions of the code in the initial discrimination method, laboratory tests related tosilty soil of this area is absolutely necessary.(4) The analysis of the liquefaction of the silty soil in Handan has the followingfactors, with the finer soil particles, the liquefaction resistance is smaller and get moreeasily liquefied, it is related to clay content; In general, silt liquefaction tests shouldadopt the undisturbed soil sample, if the sample is being effected, it will have a certaindegree to liquefaction strength; the ground acceleration is larger, the duration of shakingis longer, the silt is more easily liquefactive; the good drainage condition is beneficial tothe dissipation of pore water pressure, and it can reduce the possibility of liquefaction.The above conclusions are based on finite sample basis, in the future, for the studyof silt dynamics characteristics of this region should further expand the range ofsampling in order to get the more general rules.