| In general,natural clays are structural,but the structural properties of clays distributed in different types and regions are strong or weak.For those soils whose soil structure has a major impact on practical engineering,many scholars named them as "Structural soil." The structural soil is different from the general soil,its mechanics and deformation are often dominated by the nature of the structure in the soil,and the structural strength in the structural soil not only comes from the specific arrangement of the solid particles formed by the pre-consolidation during the historical deposition process.The inter-connections also come from the cementation of the metal ion oxide colloids in the earth and the solid particles in the soil.The soft clay in the Zhanjiang region is world-famous for its strong structural properties.Because of its anomalous combination of " poor " physical properties and " better " mechanical properties,it has also been demonstrated that it has different deformation characteristics of general soft clay soils in compressibility studies,therefore,The soft clay in the Zhanjiang region is a typical and excellent structural soil research object.This chapter relies on the Baosteel Zhanjiang Iron and Steel Project in the northern part of Dongdao Town,Zhanjiang City to study the characteristics of clay in the Zhanjiang region.The main research contents and results are as follows:1.Based on geological sedimentation history,composition analysis,physical test data,and mechanical test data,the basic physical and mechanical properties of structural soils and the formation of their structural properties were discussed and evaluated from the perspective of soil structure,which is a reference had been given for the research on the soil properties of the local similar projects in the future and its pre-prediction work.2.In this paper,the e-lgp of the indoor compressive curve of clay in Zhanjiang area is taken as the object of study.The morphological characteristics of the clay are explained by the structural mechanism.Most of the curves are ub the form of “segmented”,they are straight forward and steep back,this feature was explained through the structural damage mechanism of soil.The comparison about the phenomenon and its cause of the compression test results between the original clay and the reshaped clay is analyzed.The indoor compression curve ofremolded clay also appears like undisturbed soil,the "structural" feature of remolded clay is believed to be caused by the recombination of reconstructed cement with water.3.Based on the experimental data,the exponential function was used to fit the initial compression curve after the yield stress of the structure.The compression curve segment before the yield of the soil structure was fitted with a straight line.According to the correlation between the parameters and the correlation between parameters and basic physical indicators of soil,then the mathematical model of compressibility of structural soils in Zhanjiang area was proposed.With the verification of similar engineering data and literature data in the region,good simulation results were obtained.4.The functional relationship of the segmented structural soil compression mathematical model is reflected in the change of compressibility and consolidation of the structural soil under different stress stages.Based on the mathematical model of structural soil compression,the Terzaghi's one-dimensional consolidation theory and the theory of three-dimensional axial symmetry sand well consolidation considering well resistance and smearing effects.,the theory of three-dimensional axial symmetry sand well consolidation considering well resistance and smearing effects,the theoretical analysis formula is compiled to predict the consolidation of foundations.The finite element method was used to analyze the surcharge pre-compressed sand well foundation.The three-dimensional model of the sand consolidation foundation was equivalent to a two-dimensional plane strain sand wall model,and the drainage performance of the plastic drainage plate and sand well was also analyzed.The equivalence was established and a 2-D plane strained sand well consolidation finite element model for surcharge preloaded foundation was established.The consolidation prediction program and two-dimensional plane strain finite element model compiled above were used to calculate the degree of consolidation that characterizes the dissipation of excess pore water pressure,and compared with the actually monitored excess pore water pressure conversion degree of consolidation.The verification results show that the errors in the establishment procedure,the finite element calculation results and the monitoring data are within the allowable range of the project.The consolidation calculation program based on the mathematical model of the structural soil compression curve can be used as a practical and effective pre-work forecasting method. |
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