MJS工法在城市轨道交通车站施工中的应用

The Application of MJS Method in Transfer Node Engineering of Urban Rail Transit Station in Water-rich Sand Layer

相较于传统的旋喷工法,MJS工法较具有施工扰动小、土压力稳定、施工效果可靠等优点,可以进行垂直、倾斜和水平方向施工,在城市轨道交通领域使用广泛。佛山市轨道交通3号线桂城站换乘节点施工中,为了解决复杂周边环境下富水砂层加固效果不佳,土建施工容易引起涌水、涌沙,工程自身结构及周边建(构)筑物变形过大等问题,采用MJS工法,通过选择合理的桩径,水灰比、水泥浆压力、成桩误差、浆液流量、转速、水泥掺量等,实现了MJS高压旋喷桩芯样强度代表值均大于1.4 MPa,在富水砂层中达到了良好的止水效果。施工期间,周边建(构)筑物累计沉降最大值为3.24 mm,累计水平位移最大值为1.79 mm,均小于变形控制值,满足周边建(构)筑物的变形控制要求。

Compared with the traditional jet grouting method,the MJS method has the advantages of less construction disturbance,stable earth pressure and reliable construction effect.The method is widely used in the field of urban rail transit.In order to solve the problems that the transfer node of Guicheng station of Foshan Urban Rail Transit Line 3 was constructed under the geological conditions of complex surrounding environment and water-rich sand layer,the stratum reinforcement effect was not expected,and the civil construction cause water gushing and sand gushing easily,the MJS construction method was adopted to solve the problems of excessive deformation of engineering structure and its surrounding buildings.With reasonable selection and control of water cement ratio,cement slurry pressure,piling error,slurry flow,lifting speed,rotational speed,cement content and other process parameters,All MJS high pressure jet grouting pile core strength representative value were higher than 1.4 MPa,the pile body was continuous,the cement mixing and the cementation was effective and met the design strength requests,achieved the water stop effect in the rich water sand layer.During the construction period,the maximum accumulative settlement and horizontal displacement of the surrounding buildings were 3.24 mm and 1.79 mm respectively,which were smaller than the deformation control values,and the structural deformation control effect was good,which met the surrounding building(structure)deformation control requirements.