Effect of setting pressure relief holes on freezing expansion and unloading of frozen underground excavated tunnel
During construction of underground excavated tunnels using freezing method,frost heaving often leads to the exces-sive deformation of soil and tunnels,bringing adverse impacts on subway tunnels,surrounding environments and buildings.Taking a frozen underground excavated tunnel project in the coastal soft soil layer of Fuzhou City as an example,a nonlinear analysis for the prototype project was carried out.Based on measured data and engineering conditions,the distribution pattern of frost heave deformation and the displacement variation characteristics of frozen underground excavated tunnel before and after the setting of pressure relief holes were analyzed.The research results showed that the artificial freezing reinforcement technology combined with pressure relief holes had a better effect on the release of frost heaving pressure and the control of freezing expansion deformation.Compared with the stratum with no pressure relief holes,the pressure relief holes provided free deformation space for the frozen soil expansion after the formation of intersection circle of the permafrost curtain,thus reducing the freezing expansion displacement and freezing expansion stress of the soil.At the end of the freezing period,the maximum freezing displacement at the longitudinal profile of the center points of two frozen underground excavated tunnels was reduced from 28.88 mm to 16.67 mm,and the maxi-mum freezing stress was reduced from 335 kPa to 265 kPa,showing obvious decompression effect.The study results can provide references for artificially frozen underground excavated tunnels.
国家科技期刊平台
NSTL
万方数据
维普
