| The shotcrete technology, which can not only ensure the safety in construction as primary support, but also maintain the long-term stability and safe use of the structure as permanent support alone or combined with other supporting components, has been developed into one of the most efficient supporting means in underground engineering. But large early shrinkage, high brittleness, less toughness and bad anti-permeability and anti-crack performance are the main drawbacks of shotecrete. These drawbacks will damage the supporting structure seriously, reduce the service life of roadway and bring serious hidden danger in coal mine operation. Then how to improve the mechanical property, anti-permeability and anti-crack performance, and how to enhance the deformability and service life of supporting are the development direction of the future support material.Combined with the supporting status of the coal roadway, shrinkage-compensating steel fiber reinforced shotcrete (SCSFRS), a new support material, is obtained by using materials composite technology. According to the method of combining theoretical analysis, test research, numerical analysis with field test, SCSFRC is systematically researched. The main research work and achievements are shown as follows.(1) Starting with researching the components and action mechanism of cement, expansive agent and accelerating agent, four expansive agents are adopted in hydration reaction with accelerating agent and cement. And creation, crystal structure and mineral morphology of hydration reaction products are analyzed by electron microscope scanning (SEM) test and X-ray diffraction (XRD) test. According to the microscopic test results contrast, diffraction peak of ettringite (AFt) is higher, and bigger AFt can be seen in atlas of SEM when CSA expansive agent, accelerating agent and Portland cement hydrate 3 days. Meanwhile, it indicates that there is a good compatibility in them which is helpful to the early strength of shotcrete.(2) Combining microstructure test with requirements of specifications for bolt-shotcrete support, the basic mechanical tests of concrete with CSA expansive agent are done. Results show that variation in concrete strength become clearer with the increasing of expansive agent content. When expansive agent content is 8%, better mechanical properties can be got. And mechanical properties of concrete are improved with steel fiber content increasing. When steel fiber content increasing in the range of 1.0%～1.2%, compressive strength of concrete is almost the same and tensile strength enlarges slowly. What's more, the best mechanical result of shrinkage-compensating steel fiber reinforced concrete can be obtained when steel fiber content is 1.0% and expansive agent content is 8%. It indicates that there is a good combination enhancement between steel fiber and expansive agent.(3) Anti-permeability test and anti-crack test of SCSFRC are done to analyze and compare the crack of plain concrete and SCSFRC. And the results show that anti-crack effect of SCSFRC is the best, and its limit-crack level reaches first level. Meanwhile, anti-permeability performance is compared. The max average seepage height of plain concrete is 11.5cm, while that of shrinkage-compensating steel fiber reinforced concrete is 4.2cm which is decreased by 63.5% of that of plain concrete. So anti-permeability of shrinkage-compensating steel fiber reinforced concrete is much better.(4) Limit expansion ratio, which is an important index of shrinkage-compensating concrete, can be got from the test. With the increasing of expansive agent content, early deformation of concrete is bigger. And the main expansive deformation is shown from 7d to 14d. Expansive deformation at 14d is 0.00017 when expansive agent content is 6%. While it is 0.00028 at 14d when expansive agent content is 10%. Meanwhile the change law of limit deformation with steel fiber along with the age is almost the same with that without steel fiber. When expansive agent content is 10%, expansive deformation of concrete with steel fiber at 14d is 0.00025. So steel fiber can restrain expansion of concrete and lower expansive deformation of every age.(5)According to similarity criterion in similarity theory, plain shotcrete, steel fiber reinforced shotcrete, shrinkage-compensating shotcrete and SCSFRC are adopted to do the model test for roadway supporting structure. And various materials influence of supporting structure bearing capacity, failure mode and ultimate bearing capacity under confining pressure, and crack distribution and development form of various materials supporting structure when it destroyed are analyzed. Test results demonstrate that initial-crack load and ultimate bearing capacity of roadway supporting structure made by SCSFRC are improved about 146% and 72% respectively. Moreover ductile failure is shown in it. (6) Mechanical principle of interaction between surrounding rocks is expounded systematically in the working process of SCSFRC supporting structure. Thin-shell theory is adopted to do simplified calculation of shotcrete supporting structure, and analytic solutions of thin-shell are obtained.(7) Numerical calculation software is used to do finite-element analysis of SCSFRC supporting structure. And stress field and displacement field distribution of support are analyzed. Meanwhile, considering the effect of surrounding rock, plane and three-dimensional finite element analysis is done for bolt-shotcrete support. Distribution regularity of stress field, displacement field, plastic zone and support force are analyzed. Besides, the influence of roadway excavation to surrounding rock stability and bearing characteristic of supporting structure can be researched by three-dimensional finite element analysis.(8) Depending on the engineering of 965 level roadway in Zhuji Mine, field application is done to roadway support using SCSFRS in accordance with the principle and technical requirements of bolt-mesh-spurting support. According to the field monitoring, mechanical property and steel fiber distribution of SCSFRS are analyzed. And deformation of roadway surrounding rock is monitored, then shrinkage-compensating steel fiber reinforced concrete's control of surrounding rock deformation are analyzed and compared with plain concrete's. Finally, construction and monitoring technique of SCSFRS is preliminarily formed to help the further application and popularization of this new anti-permeability and anti-crack material. Figure 91 table 22 reference 137...
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