Study On Artificial Hard Crust Construction And Bearing Characteristics

Based on the background of the coastal soft soil foundation in the eastern Lianyungang area,this paper mainly combines the theory of double layer foundation and actual engineering needs,designing the laboratory test method and systematically studying how to construct the artificial hard crust and its bearing characteristics by means of theoretical deduction and numerical simulation,and applied it to the coastal soft soil foundation.First of all,the ratio of cement fly ash to asbestos fiber is studied,and soft soil reinforcement tests are carried out to explore the physical and mechanical properties of reinforced soil.Through the design of orthogonal test,the optimum mix ratio of cement fly ash and asbestos fiber is determined by the unconfined compression strength as 15%:1.5%:0.9%,and the single variable,direct shear test of the single variable of the macro test control fiber content,is used to study the effect on the physical and mechanical properties of the reinforced soil.It is found that the optimum content of asbestos fiber is 0.9%,and the tensile strength is more obvious than that of the compressive strength;the mechanism of reinforcement is studied by scanning electron microscopy.Secondly,because the traditional calculation formula is not fully considered or cumbersome,the friction angle in the hard crust is set 0 to ensure that the formula is partial to safety,and the shear failure surface is simplified as a fold line form.According to the soil mechanics and static equilibrium conditions,the shear action of the artificial hard shell is considered,and the foundation width and depth are corrected.The formula of the ultimate bearing capacity of the foundation is deduced,and the rationality of the formula is verified by the results of the fifth chapter indoor plate load test.Considering the large quantity of model test engineering and limited repeatability,the two-dimensional plane strain model was established by ABAQUS,and the orthogonal test was designed.The numerical simulation analysis of hard shell foundation was carried out.The three main influencing factors((1)the thickness of hard crust H(2)Elastic modular ratio n(3)the width of the loading plate)to the limit bearing of the artificial hard crust.The effects of load on the stress,strain and the development of the failure surface are reflected by the simulation results,and the effects of the body,shear,diffusion and sealing of the artificial hard shell in the loading process are studied.Finally,combined with the fourth chapters of the related conclusions,the main influence factors of artificial hard crust thickness H are studied and analyzed,and the indoor model test of different thickness is designed.It is found that the ultimate bearing capacity of the foundation is linear with the thickness of the thickness of H,and can be obtained by combining the test results with the P-S curve.The artificial hard crust foundation will be loaded under the vertical loading.There are three stages of stress deformation characterized by stress concentration inside the hard crust layer: elastic,elastoplastic and ultimate state three stages.