| With the large-scale construction of transportation infrastructure in China,soft rock tunnel support has become an important problem faced by underground engineering.Traditional support methods can not effectively solve the problem of large deformation of tunnel soft rock.Prestressed anchor cable has the unique advantages of active support,combination of rigidity and flexibility,giving full play to the bearing capacity of deep surrounding rock,high efficiency and lightweight,which provides a new support means for soft rock tunnel.Based on a high geostress soft rock tunnel with large deformation,the pre-stressed anchor cable is applied to the initial support of the tunnel.The construction technology and quality control method of the pre-stressed anchor cable of the soft rock tunnel are studied,which can provide reference for the support construction of the soft rock tunnel.Specific work contents are as follows:(1)The deformation characteristics of soft rock and the factors affecting the deformation of soft rock are summarized.The structural characteristics of special pre-stressed anchor cables for tunnels and the mechanism of their application in supporting soft rock tunnels are analyzed.(2)Based on a large deformation tunnel in high geostress soft rock,the stress and deformation characteristics of soft rock tunnel under the condition of pre-stressed anchor cable support and the influence of tunnel excavation cycle footage are analyzed by FLAC3 D.The safety factors of surrounding rock excavation and support under different footage lengths are analyzed by Drucker-Prager yield criterion.(3)The construction technology of pre-stressed anchor cable support based on soft rock tunnel is studied,including the main work of drilling,installation,anchoring,tension and so on.At the same time,the fast loading method and automatic tension technology of pre-stressed anchor cables for soft rock tunnels are put forward.(4)The destructive test,acceptance test and creep test method of prestressing anchor cable are preliminarily analyzed.The testing principle,testing technology,data analysis method and judgment standard of effective prestress of prestressing anchor cables are studied. |
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