Research On Dust Fall Technology Of Shotcrete Support

The dustfall technology of shotcrete supporting, is to ensure that shotcrete supporting performances are good, then to research the dustfall technology.By the mechanism of dust production, its causes are obtained. The internal causes are materials mixed unevenly and low viscosity materials; The external causes are the role of high-speed air flow and entrainment in the injection process, the collisions among the moving materials and the collisions during the materials and tunnel wall.To reduce the dust from the external causes, it can be done by setting reasonable parameters of shotcrete construction technology. To increase the cohesion of shotcrete, it can be solved by setting admixture and the ratio of materials. This article focuses on setting admixture to research the dustfall technology of shotcrete.By the matching experiment between the admixture and cement, the performance parameters of JA-type- admixture, setting time and compressive strength, basically meet the national standards. A new composite admixture mainly consists of JA-type-admixture. And at the same time, some other additives are added into the new composite admixtureThe dustfall tests about the new composite admixture have been done, including coagulation properties, compressive strength, wettability, viscosity, PH, electrochemical properties and micro structure. Relative to the general admixture, the new composite admixture has greatly improved all aspects of performance.Set in the reasonable parameters of shotcrete construction technology and the ratio of shotcrete materials, on-site testing have been done. The results showed that all the dust concentration decreased 46.5% -62.9%, respiratory dust concentration decreased 20%-33%; uniaxial compressive strength is 1.89 times than before. The on-site effects are good results.