Rapid Determination Method And Application Of Consolidation Characteristic Index Of Building Foundation Soil

Consolidation has an important influence on the engineering properties of cohesive foundation soil,and it is closely related to the engineering problems of seepage,settlement and stability of building and foundation.With the consolidation process,the effective stress between the grains and the density of the soil are constantly changed,and the strength of the soil is also changed accordingly.Consolidation of foundation soil depends on the speed of soil drainage and is a factor of time.For the study of consolidation characteristics of foundation soil,scholars at home and abroad usually adopt the conventional consolidation test method.However,the conventional consolidation test takes a long time,so scholars have successively studied the fast consolidation method which is short in time and high in efficiency.In this paper,based on the rapid consolidation theory of previous scholars,the instantaneous loading rapid consolidation method is proposed,and the self-developed rapid consolidation instrument is used to study the consolidation characteristics of the foundation soil of a building in a region of Hebei.The main contents and results are as follows:(1)Based on the one-dimensional seepage consolidation theory of Terzaghi,the instantaneous loading rapid consolidation test principle is deduced,and the relationship between pore ratio,compression modulus and consolidation coefficient and effective stress is obtained,which provides a theoretical basis for analysis of consolidation characteristics.(2)Dozens of instantaneous loading and conventional consolidation tests were carried out for four kinds of classical clay materials.By drawing the e-logσ’、E_s-logσ’、C_v-logσ’ curves of the two kinds of tests,the feasibility of the fast consolidation test instrument and the accuracy of the test results were verified.(3)According to the"standard for geotechnical test methods"(GBT50123—2019),a large number of conventional physical and mechanical tests were carried out on the samples in the foundation soil of a certain construction project in Hebei province,and the corresponding physical and mechanical property indexes were obtained,which provided the basic parameters for the later software simulation.(4)Routine and rapid consolidation tests were carried out again for the original and remolded subsoil samples in a certain area of Hebei Province.Then the six soil layers of the rapid consolidation test,analysis of the consolidation characteristics of each layer of soil,mainly from the following points:①Analyzing the deformation of each layer of soil under load.②Determining the pre-consolidation pressure of each soil layer and Judging the consolidation state of the soil layer.③Measuring the compression modulus and compression coefficient of the soil layer,and judging the compressibility of the soil layer.④Drawing the C_v-logσ’ curve to determine the range of consolidation coefficient.(5)Based on the results of the fast consolidation test and a certain construction project in Hebei Province as the background,the settlement and deformation of the foundation under static action are checked:①The final deformation of the building foundation is calculated by the layering summation method.②The software is used to simulate and analyze the foundation deformation process,which provides a reference for analyzing the settlement law of the building.