Experimental Research On Dynamic Stress-strain Relation Of Reclaimed Soil In Binhai Of Tinjin Under The Cyclic Loading

In the center of Tianjin, there is a special area called the Tianjin Binhai New Areaand it is a typical area with the paralic-coastal sedimentary soft soil. But in recentyears, with the development of the Binhai New Area, to make the reclaimed landepeirogenic has become the main way of Binhai New Area to utilizate the landresources, now hundreds of square kilometers reclaimed land has been completed, inChina the largest reclaimed land project is in Tianjin Binhai New Area. But now,subway has been a very important transport in many cities, the advantages andpracticability have been recognised by many countries. In Tianjin, the reclaimed soil asa special soil, it’s distribution range is very small and the composition and sedimentaryenvironment is very different according to the different region, so carrying the bigscale traffic projects on the reclaimed land, how to reasonably evaluate the changes ofthe soil characteristics under the dynamic load, to research the dynamic response ofthe reclaimed soil under circulating load has very important significance, whether in thedevelopment of the discipline of soil dynamics, or in the engineering projects.In view of the above problem, this paper as the reclaimed soft soil of TianjinBinhai New Area as the experimental material, on the basis of predecessors’ research,with the GCTS hollow cylindrical apparatus, to study the test characteristics ofreclaimed soil under dynamic load by indoor test means. The major process andresults are summarized as follows:(1) By the indoor test to understand the basic physical and mechanicalcharacteristics of Tianjin Binhai reclaimed soil.(2) By carrying the indoor undrained dynamic triaxial test on the Tianjin Binhaireclaimed soil under the condition of undisturbed soil sample, to study the relationshipbetween the dynamic stress and dynamic strain under the cyclic loading, to find outthe critical cyclic stress ratio, and to analyze the confining pressure, consolidation,vibration frequency, cycle time, waveform, other relations and to study the influenceof pore pressure, dynamic elastic modulus, damping along with the change of vibration cycle times.(3) To establish the dynamic stress-strain curve fitting equation under the differentconfining pressure, by using the critical dynamic stress as the normalization factor,and with the confining pressure and vibration times, to compare with the traditionalbackbone curve model.(4) Out of tradition basis of the backbone curve, namely a method to establish thestructure of the hysteresis curve by combining different correction laws, but from thehysteresis curve of the test results, to directly establish the hysteresis curve equationbased on the test result, and to divide the hysteretic curve into two parts, one isloading phase curve and another is unloading phase curve, through the calculatedseparately fitting to get the hysteresis curve of the reclaimed soil.