Overview of seismic methods for Urban Underground Space

The development of Urban Underground Space (UUS) has become an effective way to solve the problem of urban space. Seismic methods have achieved good results in underground engineering construction, active faults detection, urban geological structure detection and other fields. Active source seismic methods in UUS include reflection methods, refraction methods, surface wave methods and vertical seismic profile (VSP) methods and so on. Ambient noise method is also rising gradually, which becomes an important method of urban underground space detection in the future, because it overcomes the problem that the active source method is interfered by urban noise. We briefly summarize these methods and introduce the application examples of UUS.

Vulnerability Assessment of Existing Low-Rise Reinforced Concrete School Buildings in Low Seismic Region Using Ambient Noise Method

Ground movements triggered by the Bukit Tinggi earthquakes in 2007 to 2009 are believed to be the possible cause of several structural damages on a secondary school building of SMK Bukit Tinggi, in the state of Pahang, Malaysia. This paper describes the ambient noise study conducted on the damaged building (a 4-storey reinforced concrete frame laboratory building) and the adjacent buildings using tri-axial 1 Hz seismometer sensors. Fourier amplitude spectra (FAS) analysis was applied to determine the buildings natural frequencies for vulnerability assessment of the damaged structure in both longitudinal and transverse axes. Significant multiple peaks of FAS curves used for natural frequencies determination of the buildings show values between 4.18 to 4.34 Hz, 5.04 to 5.23 Hz, 6.07 to 6.54 Hz and 8.17 to 8.81 Hz, indicating the existence of translational and torsional vibration modes acting on the buildings. Differences in dynamic behaviour between the laboratory and the adjacent buildings may be responsible for the structural damages due to the independent structural response and excessive torsional effect during the Bukit Tinggi earthquake tremors.