Construction Technology Reseach On Portal Secion Of Shallow Buried Bias Tunnel With Small Span

Taking the Huangmaoling tunnel in Rucheng-Chenzhou express way as the background, the abnormal phenomenons during construction process and its treatment measures of shallow buried bias tunnel with small span in portal section were studied by means of insitu monitoring and numerical simulation. The main contents as following:(1) The engineering characteristics of tunnel portal section, supporting mechanism and construction methods were reviewed systematically, and then, the defects of construction methods and treatment measures of shallow buried bias tunnel with small span in potral section at present were pointed out and discussed.(2) Based on the insitu monitoring datum during the construction process, the change laws of monitoring indexes on tunnel portal section were analyzed comprehensively, also the reasons on abnormal deformation and cracking during construction process were found.(3) Combaning the existing practice empiric and theory basis, series of nichetargeting treatment measures for dealing with the abnormal phenomenons of shallow buried bias tunnel with small span in potral section were advanced and applied.(4) According to the finite element theory, an numerical model of shallow buried bias tunnel with small span in portal section was estabilsed, and the reinforcement measures and treatment measures applied in the engineering were calculated and verified. At last, the mechanical characteristics of three different construction mehods were compared and analyzed futher. At present, the construction of Huangmaoling tunnel is finished, each monitoring indexes have trend to be stabilize, the practice indicates that the treatment measures advanced in the thesis is reasonable, and have significant reference value for other similar engineerings in future.