After excavation of tunnel, stress from initial stress field will be relieved, which will inevitably arouse deformation of various forms, such as arch crown subsidence, surrounding rocks from two sides squeezing in, bottom parts plumping up and tunnel face squeezing out, etc. Then it will cause slack, even instability and collapse. So the purpose of tunnel design and construction is to control slack and deformation in admissible scope.
As we know, the basic purpose of tunnel construction is to build long-term stable structural system in all kinds of geologic bodies for several aims.
From point of structure, this structural system includes surrounding geologic bodies and several supporting structures. Surrounding geologic body is the main supporting body, which has the leading function.
While, these geologic bodies have big uncertainty, which brings many problems for our design and construction of tunnel. At this time, external supporting structures are always used to maintain engineering’s stability.
By grouting, self drilling hollow bar bonds with geologic bodies and then reaches to effect of stabilizing engineering. It can be installed during process of tunnel excavation, which can realize that construction and support carry out simultaneously. It can also enhance construction efficiency, ensure workers’ safety and engineering’s quality.