Study On Lining Repair And Reinforcement Technology Of Tunnel Corroded By Sulfate In Large Area

At present,there are more than 4000 old railway tunnels served more than 40 years in China.These old tunnels are prone to corrosion deterioration under the combined action of various corrosive substances,ambient temperature and humidity.Corrosion will affects the operation safety and service life of tunnels.By means of field investigation,numerical analysis,indoor test and theoretical analysis,this thesis studies the repair and reinforcement technology of tunnel lining widely corroded by sulfate.The main research work and achievements are as follows:(1)Based on the on-site disease investigation and sampling indoor detection of the HTG tunnel,the distribution characteristics and causative mechanism of tunnel lining diseases were studied.The results show that the HTG tunnel mainly has lining corrosion and deterioration,cracking,water leakage and surface salt crystallization.These diseases are mainly induced by the corrosion which is caused by the groundwater of high sulfate.(2)The calculation model of the corroded tunnel lining structure was established.The multi-condition analysis of the internal force distribution and overall stability of the tunnel lining structure under different corrosion and deterioration states were carried out.The results show that after large-scale corrosion,the safety factor of the side wall and the arch foot position decreases significantly.The corrosion will also enlarge dangerous sections,which endangers the safety of the overall tunnel structure.Furthermore,the calculation method of safety probability of large-area corrosion tunnel lining structure was proposed using the series-parallel theory.The corresponding safety grade classification method was given as well.(3)Two reinforcement method,which using the channel steel and the corrugated steel plate respectively,were carried out to repair the corroded tunnel lining structure.The stress and deformation laws and failure modes of the components were analyzed.The test results show that the failure stage of the specimen reinforced and repaired by the channel steel method or the corrugated steel plate on the tension side can be divided into the non-crack stage and the working stage with cracks.The bearing capacity and flexural stiffness of the specimen are significantly improved.Besides,the specimen basically satisfies the assumption of plane section during the loading process,and the concrete strain is linearly distributed along the section height.(4)According to the test results,the calculation method of the structural bearing capacity of the corroded tunnel lining after reinforcment is derived.The reinforcement scheme was tested,and the results show that the established calculation method of structural bearing capacity after reinforcement is reliable and can be used for the repair and reinforcement design of large-area corroded tunnel lining structures.89 figures,19 tables and 96 references.