English：

In order to solve the problems of cracking and voiding caused by uncompacted vibration orlarge plastic deformation of concrete in anchorage slot of unbonded prestressed structure in long-distancediversion tunnel, the effects of fly ash content, expansive agent content and water-binder ratio on strengthand limited expansion rate were studied. The micro-expansion self-compacting concrete was designed,and its free volume deformation and autogenous shrinkage were measured. The results show that when thewater-binder ratio is 0.40, the content of fly ash is 25%, and the dosage of expansive agent is 30kg / m3,the 28d flexural tensile strength is 4.77MPa and the 28d compressive strength is 53.6MPa, respectively,and the impermeability grade is greater than W11. The autogenous volume deformation of concrete is 20 ×10-6in 60d, which tends to be basically stable, and the drying shrinkage is about -460 × 10-6in 90d.The moisturizing curing of micro-expansion self-compacting concrete should be strengthened, and the timeof moisturizing curing should be prolonged to facilitate the performance of expansive agent.