Research On Development And Performance Of New Anchorage Material For Full-Length Bonded Bolt

China is the country with the largest scale and difficulty of underground space development.With the implementation of national strategies such as transportation power,underground engineering construction has been continuously transferred to complex areas in the central and western regions,and large deformation disasters have occurred from time to time.Full-length bonded bolt support is a widely used and simple operation support form.However,the traditional anchorage materials have the problems of long setting time,low compressive strength and low expansion rate,resulting in little effect on deformation control after some tunnel support.Therefore,it is urgent to study the anchoring materials for such engineering problems.In this thesis,the setting time,compressive strength and expansion rate of anchorage materials are taken as the main evaluation indexes to develop a new anchorage agent suitable for large deformation tunnels.Theoretical analysis,numerical simulation,laboratory test and field test are combined to realize the effective prevention and control of large deformation of ull-length bonded anchor.The main research results are as follows:(1)Through the combination of theoretical analysis and numerical simulation,the synergistic mechanism of surrounding rock-anchor-anchoring material is studied.It is found that the anchoring material has a significant influence on the anchoring system.Through the case study and theoretical analysis of anchorage failure engineering,it is concluded that the main controlling factors affecting the performance of anchorage materials are setting time,expansion rate and compressive strength.Based on the theory of mineral hydration mechanism of cement-based materials,combined with the main controlling factors of the performance of anchorage materials and the needs of engineering sites,a reasonable explanation of the preferred admixture is made.(2)The optimal ratio of the new anchorage material was determined by orthogonal test and test results:water cement ratio 0.3,water glass content 25%,early strength agent content 2.5%,expansion agent content 9%.By comparing with the physical and mechanical parameters of three traditional anchoring materials,it is concluded that the initial setting time and final setting time of the new anchoring material are further optimized,and the 3d expansion rate,7d expansion rate,1h compressive strength and 24h compressive strength are all increased by more than 100%,which achieves the research and development goals and meets the engineering requirements.(3)Through the combination of indoor pull-out test and theoretical calculation and analysis of pull-out resistance,soft rock samples were obtained at the engineering site,and pull-out tests were carried out under different anchoring materials.The results show that the ultimate pullout force of the new anchoring material is 10.8 kN,which is far superior to the traditional anchoring material and ordinary Portland cement.By observing and comparing the failure modes during the pull-out process,the new anchoring material causes the anchorage body to crack when subjected to the pull-out force,while the traditional anchoring material and ordinary Portland cement appear debonding,thus verifying the superior anchoring performance of the new anchoring material.(4)Through long-term immersion,the law of anchorage material under the condition of single sulfate and carbonate solution erosion was studied by taking strength change and morphological characteristics as evaluation indexes.The durability mechanism of the new anchorage material was revealed by using the characteristic method of XRD and SEM.The results show that the new anchorage material has excellent durability,clear three-dimensional space grid and uniform void distribution.The pore structure formed by the high interconnection between the cements is less,and the overall structure of the formed stone body is dense.Taking Chuxiong section of water diversion in central Yunnan as the engineering background,field application is carried out.The wireless acquisition system is used to carry out the comparison between the axial force monitoring of the bolt and the actual deformation results on site,which verifies the superiority of the new anchoring material in large deformation control.