Sonar Detection and Comprehensive Treatment of Water Inrush Disaster for Metro Station Deep Foundation Pit in Complex Karst Strata

Abstract

Objective In Foshan Area, due to the specific characteristics of the complex karst stratum, the calcareous siltstone stratum and the fracture zone can easily cause water inrush disaster in metro station foundation pit. Therefore, it is necessary to adopt sonar technology for detection and solve the water inrush problem through comprehensive treatment. Method Taking Zhongshan Park Station of Foshan Metro Line 3 as the research object, the sonar detection scheme for the station is introduced, the groundwater leakage characteristics of the station deep foundation pit are analyzed based on the detection results, the spatial distribution of leakage points and the type of the water inrush disaster are determined. Based on the results of advanced drilling exploration at the bottom of the foundation pit, and the distribution characteristics of the water inrush points in the foundation pit, a joint sealing scheme for leakage in the foundation pit is proposed, including a retreating double liquid grouting waterproofing curtain outside the pit and a pit interlocking rotary jet grouting pile. The key construction techniques of the retreating double liquid grouting, interlocking rotary jet grouting pile and MJS (metro jet system) pile are emphatically described. The groundwater leakage speeds at representative test holes before and after comprehensive treatment are compared to verify the treatment effect. Result & Conclusion The sonar detection technology can accurately detect the specific spots of the deep foundation pit water leakage points in karst stratum and the relevant parameters of the seepage field. The adopted joint sealing scheme of double liquid grouting, double pipe rotary jet interlocking pile and MJS pile can effectively solve the technical problem of large-scale water inrush and leakage in deep foundation pit excavation in complex karst area.

Keywords

• metro station
• deep foundation pit
• water inrush disaster
• sonar detection
• karst stratum
• joint sealing technology