Risk factors of buildings safety, taking a hotel as an example, induced by line 3 of Qingdao subway excavation are summarized based on detailed exploration and investigation of rock and soil mass properties underground, hydrological properties, tunnel excavation and support methods, building structure type and foundation form. Mechanism and development trend of various factors are studied under cavern. The characteristics and laws of influence factors are summarized. The degree of building damage and influence of various factors on building safety are predicted. Technical approach is studied to avoid the risk. Specific measures are proposed to control the risk. These results will provide a useful guidance for tunnel excavation of Qingdao and also in similar area.
Rock and soil mass surrounding a tunnel will be inevitably disturbed by tunnel excavation. The original equilibrium state of geotechnical body was destroyed. The original in situ stress will redistribute which leads to the subsidence and deformation of surface. Thereby, the safety of the existing buildings on the ground will be threatened. It should strictly control subsidence and deformation of the strata and the buildings on the ground for buildings safety when anomalies occur during tunnel excavation. Pre-recovery measures should be taken to control further damage to the buildings and ensure the structure safety when subsidence value and deformation value exceeds the allowable value. The practice shows that the grouting is one of the effective measures to reinforce strata, reduce strata subsidence and protect the existing buildings on the ground (Yuan 2010).
Taking a hotel as an example, the subsidence value of the building foundation is predicted based on numerical simulation respectively, without grouting, grouting in weak strata and grouting in weak strata and within 1 m above, Grouting effect of weak strata is analyzed.