Abstract: In order to study the ground settlement law during the construction of the singlelayer mined station in silty sand layer by columnhole method, the method of grouting test, numerical analysis and onsite monitoring and measurement are combined and adopted. The problems in design and construction of columnhole method in silty sand layer are analyzed, and an optimized design method is put forward. The results show that: (1) The grouting reinforcement can significantly improve the moisture content, cohesion, internal friction angle and compression modulus of silty sand layer. (2) The ground settlement and settlement groove induced by columnhole method are large in silty sand layer. (3) Problems such as narrow construction space, large sidespan construction settlement, and difficulty in comprehensive grounding construction exist in columnhole method construction. (4) The optimized singlelayer mining construction scheme are characterized by small settlement, mechanized construction, time saving and convenient construction. 

Key words: mined station, columnhole method, silty sand, grouting test, numerical simulation, monitoring