Research On Tunnel Support Technology Based On Active Control Of Surrounding Rock Deformation

The deformation control of tunnel surrounding rock is a difficult problem in the design and construction of traffic tunnel,and it is also one of the problems that scholars at home and abroad pay attention to and study for a long time.With the extension of China’s railway construction to the central and western regions,more and more tunnels are faced with complex and special geological conditions,such as high ground stress,weak and broken surrounding rock,etc.There are some adaptive problems in the existing deformation control theory and technology,and the effect is not ideal in some tunnels,so it is necessary to further study the deformation control method.In this paper,by means of data investigation,summary,theoretical analysis,numerical simulation,indoor test and field test,the deformation characteristics of tunnel surrounding rock and existing deformation control technologies are summarized,the support concept based on active control of surrounding rock deformation is elaborated,and the support parameters,engineering materials and quality control are studied.The main research work are as follows:(1)The deformation and failure characteristics of typical soft rock tunnel with large deformation are analyzed,and the influence of geological structure,surrounding rock conditions,in-situ stress characteristics,groundwater,engineering and other factors on surrounding rock deformation is analyzed.The main supporting parameters,deformation control measures and adaptability of each case were mastered;The initial supporting parameters and deformation control characteristics of general geological tunnels in China are sorted out.(2)The basic principles of NATM,ADECO-RS,the surrounding rock loose circle theory,the primary and secondary bearing zone theory,and the synergistic design theory method of tunnel support structure system.On this basis,the supporting concept based on the active control of surrounding rock deformation is proposed.The main types and implementation points of active support are put forward.(3)The mechanism of rockbolt and shotcrete is studied;the influence of length and density of rockbolt,anchorage mode and combination type of prestressed bolt,thickness and adhesive force of shotcrete on deformation is studied.Based on Jingzhai Tunnel of Yumo Railway,the field test of active support is carried out,and the results show that the deformation control effect of high prestressed anchor cable support is good.(4)The flexural toughness of fiber reinforced concrete is studied,and the possibility of fiber reinforced concrete replacing "steel mesh + shotcrete" is explored.The high early strength shotcrete has been developed and tested in Gaojiaping Tunnel of Zhengwang high-speed Railway,which proves that it has the advantages of high early strength,low rebound ratio,economy of materials and construction efficiency improvement.The reasonable mix ratio and performance requirements of cementitious grout and cement capsule anchoring agent are studied;the shotcrete construction quality inspection technology based on three-dimensional laser scanning and the nondestructive inspection technology of anchoring quality based on the acoustic reflection method are studied.