Settlement Research Of Vacuum Combined Heaped Load Preloading Method Considering The Damage Of Soil Sample

The soft soil was widely distributed in China’s coastal areas, the lake area and both sides of the inland river, which was not only has the natural water content, natural void ratio, high compressibility, low shear strength and bearing capacity, but also has significant structural. In recent years, the structural study of soft soil mainly for consolidation strain process and construction sectors. In fact, when the soft soil was in the course of drilling, transport and sample preparation, the inevitable result of disturbance caused by its structure character change, resulting in the test samples (disturbed soil sample) mechanical indicators could not reflect the mechanical characters of soil in situ, thus affect the calculated results and the engineering. The paper selects Fuzhou Lianjiang silt soft soil as a representative to study, though the complex damage model which was proposed by damage theory, and take the damage variables to evaluation the sample disturbance damage caused by transportation and preparation. In the settlement calculation research of vacuum combined heaped load preloading method, introduce the consolidation settlement calculation model proposed by the damage soil mechanics to considering the influence of disturbance damage brought on mechanical index test. Compared with field measured data, the calculation data after comprehensive correction obtain more reasonable and satisfactory results.Firstly, through to the Fuzhou Lianjiang sports center construction project soft soil (silt) of undisturbed, remolded soil samples’basic physical properties test, consolidation test and the consolidated undrained three triaxial test, corresponding the e-logP curve, structural strength, stress-strain curve, circle of stress and strength line. Research shows that:Compared with the mechanical index of the undisturbed soil sample, the compression coefficient of disturbance soil sample and compression index were increased by about 10%, while the remolded increase is more obvious, at about 25%; disturbance and remolded soil sample cohesive strength are decreased by about 10%,40%, but the friction angle does not change significantly, are maintained at about 1°～2°; the damage causes of disturbed soil samples of structural strength andbearing capacity of the foundation was reduced by about 10%, while the remolded soil is more obvious effects of disturbed soil, about four times or more, up to 40%; the damage variable of disturbed soil sample is 24.0%, and the structural damage caused by the disturbance is obviously and can not be ignored.Secondly, according to the existing calculation model of consolidation settlement of vacuum stack preloading method and considered the influence of structural damage and then combined with the vacuum stack preloading engineering in Fuzhou Lianjiang Kemen Economic Development Zone, the A1-9 plots was selected as the earliest start block to study. And then the measured settlement curve of A3-2 plots and other plots of measured settlement data was used to calculate the average comprehensive correction coefficient, it shows that:the deviation of the final settlement without correction calculated value and the measured value is up to 8%～12%, while the deviation of the correction of the final settlement calculated value and the measured value is only -3%～3%; similarly, the fitting degree of the modified time course curves of settlement and the measured settlement curves has also been significantly improved; and the comprehensive correction coefficient ranges from 0.85～0.95 when the disturbance index is substituted into the damage model.The results of the study can be used for the engineering practice and in reference to theoty research in Fuzhou area even the soft soil area of east coast of China’s.