Research On The Principle And Parameters Of Flexible Formwork And Pump-concreted Support

Flexible formwork and pump-concreted support technology is a new useful support technology. This technology is the first time to use flexible formwork in the field of underground support,and it provides a new method for human to develop underground space and to mine underground resource. Flexible formwork and pump-concreted support in advance makes fiber flexible formworks,sencondly fixs fiber flexible formworks along the tunnel surrounding rock with bolts and steel meshes,thirdly pumps high flowing no-vibration self-compation concrete mixing meteria into flexible formwork,after concrete hardening, forthly shots concrete on the flexible formwork,forming a bolt-arch combined supporting structure. Flexible formwork and pump-concreted supporting structure inherits continuous intergral support's rigidity,and has both flexible and active support's advantages of bolt supporting, also this structure adds the connection with bolts between the surrounding rock and flexible formwork arch,making surrounding rock,bolts and flexible formwork arch deform together,resulting in a high loading capacity and greater stablity.This support method constructs a large area in a single time,forms good intergrity and high strength concrete,and has high machanization degree,constructs quickly.This technology has outstanding superiority on economy,ecological environment and social benefit.This paper first puts forward the calculating model of flexible formwork and pump-concreted support structure based on combined arch principle,combined beam theory, thick tube theory, pu's theory the book of Code for Design of Road Tunnel.This model's mian bearing structure is flexible formwork arch,combined arch and bolts. The formula of moment derived by material mechanics about combined beam with rock and arch,proves that the combined beam with rock an flexible formwork arch can decrease the moment of flexible formwork acrh effectively.The moment of combined beam with rock and flexible formwork arch is related to thickness of combined arch,elastic modulus of surrounding rock and the parameters of bolt on condition of the same surrounding rock pressure.This paper disscuses the principle of rigid and flexible layers support.and derives the relation of arch moment with buffer layer's elastic modulus and thickness,also simulation calculates the effect of buffer layer to arch's bearing load,leading to that the buffer layer impacts the arch's bearing load greatly.This paper presents the calculating methods on flexible formwork,steel mesh,bolt's geometry size and arrangement,the concrete thickness for support,which is simple and useful, having been adopted in flexible formwork support.Calcultes the span and side pressure of tunnel based on pu's theory,and calculates the roof pressure based on Code For Design of Road Tunnel.;calculates the arch supporting thickness of concrete by combining thick tube theory and safety factor of road tunnel design,and the wall supporting thickness of concrete can be chosen by the strength of concrete and checking calculation for stability.This paper disscuses the properties of explansible soft rock and high stressed soft rock,puts the bolt-arch-buffer layer combined support structure,still combines predecessors'calculation on soft surrounding rock's displacements and pressure,abtians the surrounding rock pressure of arch of bolt-arch-buffer layer combined support structure.This paper simulation calculates the flexible formwork and pump-concreted support structure of hongliu mine vice inclined shaft,checking that its strength and stability meet design demand.In the end presents the costruction technology and quality control based on hongliu mine's flexible fromwork and pump-concreted support.Theoreritical calculation,numerical simulation and engineering application provde the flexible formwork and pump-concreted support principle.The design method is simple and useful.It can give a strong guiding for the later engineering design.