Study On Load-bearing Characteristics And Engineering Application Of Fiber Reinforced Geopolymer Support Structure

It is necessary to find a new type of flexible concrete supporting material with large deformation resistance and high strain rate for cooperative support,so as to achieve the supporting effect of supporting structure and surrounding rock.In this study,the fiber reinforced concrete composite materials with different proportion of fly ash,slag,cement and PVA fiber were used.Through the analysis of basic mechanical properties such as bending and extension,the reasonable volume ratio of fiber and the best proportion of matrix components were obtained.Through physical model test and numerical simulation,the deformation and failure characteristics of different EGC support structures with different thickness and different support structures were analyzed The load-bearing characteristics and evolution law of fiber-reinforced geopolymer and engineering cement-based materials as large deformation resistant support structure are obtained.(1)The engineering cement-based materials(ECC)and fiber-reinforced geopolymer(EGC)with different proportions were prepared,and the bending and cracking behaviors of different fiber-reinforced support materials and structures were analyzed.The results show that with the increase of the content of final fly ash and the increase of sand ratio in EGC,the compressive strength and elastic modulus decrease,the number of micro cracks increases,the bending strain and strain hardening ability increase,and the crack width concentrates in 50-80 μ m;the compressive strength and elastic modulus and fiber In addition,the compressive strength of EGC is generally better than that of ECC,the tensile strain is more stable than that of ECC,and the bending and large deformation resistance of fiber reinforced geopolymer is stronger.(2)In order to reduce the support cost and optimize the support structure,the mechanical behavior and deformation failure characteristics of fiber reinforced concrete FGM under different working conditions were analyzed.When the thickness of fiber-reinforced geopolymer(outer bending part)is half of the total thickness,when the fiber content is 1.4%,the bending strain hardening ability and tensile strain rate are the largest;because of the role of fiber,with the increase of the thickness of fiberreinforced Geopolymer in the support structure,the bending performance and tensile strain increase continuously,when the thickness(outer bending part)is 0.67 h,the property price The ratio is the highest.(3)Based on the large-scale simulation test-bed,the deformation and failure characteristics of support structures with different shapes and thicknesses are simulated,and the deformation law under the joint action of deep underground support geopolymer structure and surrounding rock is analyzed.The research results show that in order to achieve the effect of toughening and multi crack failure of support structure,it is most advantageous to design the thickness of shotcrete support structure at 1cm under the condition of this physical test.Compared with the semicircle arch,the deformation and failure of the circular support structure is more regular,mainly in the top and bottom plate and the two sides,and the most serious part of the semicircle arch failure occurs in the bottom plate.(4)Based on the cmosol software,the strain strengthening model of supporting structure and the strain softening model of surrounding rock,the deformation,failure and evolution law of different fiber-reinforced polymer shotcrete thickness,different functional gradient materials and surrounding rock are simulated and analyzed.The difference between fiber reinforced support structure and common support structure is analyzed.The results of bearing characteristics of different shotcrete support materials are EGC,ECC and common concrete from good to bad.When the thickness of shotcrete layer is 15-20 cm,the bearing characteristics of shotcrete support materials are good,and the fiber reinforced support structure shows strong ductility and large deformation capacity.At the same time,the internal stress component of fiber reinforced support structure More uniform distribution,no obvious stress concentration,etc.,can better limit the deformation of surrounding rock and improve the stress effect of surrounding rock.There are 94 figures,24 tables and 102 references in this paper.