Research On Method Of Earthquake Liquefaction Estimation Of Saturated Soil In Yellow River Delta

According to datum, the foundation soil of the Yellow River Delta is saturated silt which is tend to liquefy. And the saturated silts have uncommon properties, which differs from other soil. At present, research work about liquefaction of this area is few. And the methods are formulas coming from criterion. Based on macroscopical earthquake calamities and laboratory tests, the traditional methods about estimation and grade evaluation of liquefaction are induced by means of generalization, analyses and statistics, which have some practicability and more limits. More research work is going to be done in order to validate these methods holding true or not. It is of pertinence and science to analyse dynamic properties of silts through test. Numerical simulation synthesizes knowledge of maths, mechanics and computer to analyses liquefaction of foundation, which is strictness and takes into account multi-factors. Artificial Neural Network can forecast more accurately and quickly, which concern minor factitious influencing factors and embrace qualitative and quantitative indexes.Aimed at the geo-engineering properties of sediments in the Yellow River Delta, the tests in the spot and in the lab, the research about dynamic properties and numerical simulation are carried through. The thesis draw some conclusions as follows.1) Research work about dynamic properties of silts is studied using cyclic loading test, including critical pore water pressure ratio, pore water pressure model and shear strength model. The critical pore water pressure ratio of silts arrive at 0.65, foundation soil can be considered liquefaction.2) Using traditional methods of liquefaction estimation, when aseismatic fortify intensity is 7°, a majority of foundation soil in research area will not liquefy; only afew soil layers are likely to liquefy.3) By numerical simulation, the developing rule of pore-water pressure and the liquefiable probability is analyzed. The pore-water pressure radio in surface grows rapidly. The foundation soil in Dawangbei, Dongyinggang and Xintan research areas is tend to liquefy. The estimating results of numerical simulation are comparatively accordant with that by traditional methods. Furthermore, the former is more comprehensive and secure.4) Adopting Artificial Neural Network, the estimation of foundation soil liquefaction is carried through. When aseismatic fortify intensity is 7°, a majority of foundation soil in research area will not liquefy; the foundation soil have great capability of anti-liquefaction. The result is compared with that of traditional methods, which is quite accurate. And based on estimating results, the thesis put forth propositions to criterion.