Influence Mechanism Of Grouting Well Onmechanical Performances Of Concrete Filled Steel Tube

In recent years,with the increasing of mining depth of coal mine,the bearing capacity of the support is becoming stronger and stronger.The traditional support method is more and more difficult to meet the requirements.The concrete filled steel tube has the advantages of simple structure,strong bearing capacity,good fire resistance and low cost.It is widely used in Civil Engineering.Due to the above advantages of steel tube concrete,the concrete filled steel tubular structure is gradually introduced into the coal mining.Due to the small underground working space,the construction requirements are more special.In engineering practice,it is necessary to set grouting holes on the surface of concrete filled steel tube to facilitate grouting.In order to meet the needs of construction and bearing capacity,this paper uses the method of experiment and numerical simulation to study the influence of opening on the bearing capacity of concrete filled steel tube.And the appropriate reinforcement measures are designed to make up the decrease of bearing capacity.It provides a theoretical reference for the popularization and application of the concrete filled steel tubular support with grouting holes in deep coal mining.On the basis of relevant research,this paper obtains the following results:(1)It is confirmed that the existence of grouting hole has some influence on the bearing capacity of concrete-filled steel tube.And there was a negative correlation between bearing capacity and grouting hole diameter.Then,the failure characteristics of concrete filled with grouting steel pipe are obtained.Finally,the relationship between axial bearing capacity and pore size is obtained by statistical regression method.(2)Based on the relationship between the axial bearing capacity and the pore size of the concrete filled with grouting hole,the formula for calculating the bearing capacity of concrete-filled steel tubular members in the relevant regulations is revised,which can be used as a reference for the development of mechanical properties of concrete filled with grouting.(3)The failure mechanism of concrete pipe with grouting hole is analyzed by experiment and real numerical simulation,which provides the idea for the design of reinforcement measures.(4)The numerical simulation method is used to verify that the proposed reinforcement measures can effectively increase the axial bearing capacity of concrete filled steel tube with grouting hole to the bearing capacity of typical concrete filled steel tube.According to the relevant simulation results,it is recommended to use 2 times the length of the casing as a reinforcement measures.