Study On The Static And Dynamic Characteristics Of The Interface Between Sand And Concrete Structure

The research on the static and dynamic characteristics of the interface between soil and structure is one of the difficult issues to solve various complex engineering problems.In this paper,the static and dynamic characteristics of the interface between sand and concrete structure are studied by physical and numerical tests.The results of the research provide theoretical basis and reference for design of interaction between subway station structure and surrounding soil under earthquakethe.The paper includes the following four aspects.(1)The three-dimensional numerical shear test model of the interface between sand and concrete structure is established.Different shear box forms and sizes are designed.The thickness of the interface is about 30 mm under the condition of single shear test.It is confirmed that the displacement corresponding to the interface when the interface reaches the shear strength is about 1mm It is found that there is obvious size effect in the shear deformation characteristics of interface,but there is no size effect in the shear strength characteristics.It is concluded that the size of the interface when the aspect ratio is 1 can be regarded as the real interface,and the shear stress-strain curve of the interface under the monotonic shear path is obtained.(2)A series of single shear tests on the contact surface of sand and concrete structures under cyclic loading are completed,and the results of typical dynamic single shear tests on the contact surface are analyzed.The law that the contact surface shears first hardens and then softens is obtained.It is found that the strength and displacement of the contact surface are in different directions during cyclic shear,and the friction angle along the initial shear direction is slightly lower than that in the opposite direction,and the unloading is carried out The slope of loading section is small.Without the influence of size,the contact surface did not reach the shear strength at the first shear,reached the shear strength at the fifth shear cycle,and the strength reduced to 16% after reaching,under the normal stress of 400 k Pa,the cyclic shear strength of the contact surface was 211.7k Pa,greater than the shear strength of contact surface under static load 208.64 k Pa The angle of cyclic friction of contact surface is twenty-nine point four and slightly larger than the contact surface Static friction angle twenty-seven point six nine.(3)Based on the analysis of the size effect of the mechanical properties of the contact surface under the condition of cyclic single shear test,it is concluded that the shear strength of the contact surface is basically not affected by the size effect at thesame length height ratio,showing the consistency of the strength.It is proved that the Clough-Duncan model is suitable for cyclic load,and the shear stress-displacement fitting curve of theinterface under the cyclic shear path is obtained,which reveals the roughness and normal direction of the structural surface The influence of stress,tangential displacement amplitude,tangential control mode and cycle period on the dynamic mechanical characteristics of soil structure interface.(4)Based on the static and dynamic numerical test results of the interface and the reasonable design of the existing interface shear test device,a vibration single shear test device which can be used to simulate the dynamic contact problem is successfully developed.The physical tests of different normal stress,different shear box forms and different structural surface roughness are carried out.The typical physical test results are analyzed,and the stable results can be obtained.The performance of the instrument is good.The paper has 78 pictures,10 tables and 92 references.