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| Research on the Cracking Mechanism and Treatment Measures of Tunnel Invert Filling Structure under the Action of Water Pressure |
| ZHENG Bo1，WU Jian1，WU Eia-Long |
| (1. China Railway Southwest Research Institute Co. Ltd， Chengdu， Sichuan 611731， China; 2. China Railway Construction Investment Group Corporation Limited，Beijing 100855，China) |
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Abstract Abstract ： Research purposes ： In recent years，the cracks in the Yottomof the tunnel under the action of water pressure frequently appear，which seriously affect tlie safety of tunnel operation. In this paper，taking a tunnel as an example， the cracking mechanism of invert filling structure of tunnel is studied by numerical simulation and field measurement， and the corresponding measures of disease controlling are put forward. Research conclusions ：( 1) Under the action of water pressure， the filling structure cracks are 11 V" shape， and the cracks mainly appear in the center line of the tunnel， there is no crack near the side wall. (2) The numerical calculation and field test results of the maximum water pressure of the tunnel invert water pressure are 0. 213 MPa and 0. 2 MPa respectively. (3) If only the surrounding rock pressure is considered，the crack will not appear in the invert filling structure. Considering the interaction of surrounding rock pressure and water pressure， the maximum principal stress values will appear in the upper of invert filling structure，and the maximum principal stress values will be greater than the ultimate tensile strengtli of plain concrete, which will produce tensile cracks. (4) In the regulation of similar diseases in tunnel engineering, following measures can be taken： in the fill and the invert filling structure reinforced， rigid sleeve valve pipe grouting improve basement, between invert and surrounding rock setting groundwater drainage system and so on. (5) After several years of observation，the results of the regulation measures proposed in this paper are good and can provide reference for similar tunnel diseases.
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Received: 23 August 2016
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2017, Vol. 34 
