Study On Multi-field Coupled Effects Of Heat, Liquid And Solid In Tunnel Works

Tunnel works always exists in a certain geologic system, where groundwater, ground stress and temperature are the three main factors. Since the relations of mutual dependence, interrelation and infection lie among temperature field, seepage field and stress field of tunnel surrounding rock, such studies, which separate the three physical fields and ignore mutual coupling effects, are neither inconformity with actual project conditions nor satisfy present tunnel construction. Therefore, it is necessary to carry out the studies of heat-liquid-solid coupling effects, and prove mechanical properties and mutual effects of such media, and so, veritably reflect actual working conditions of tunnel's structure and surrounding rock. Based on such typical tunnel works under complex conditions as high-cold tunnel, high-water-pressure sub-river tunnel, etc, heat-liquid-solid coupling mathematical model, with such research method as in-situ tracking test and numerical simulation, etc, are used to carry out heat-liquid-solid coupling analysis for high-cold and high-water-pressure tunnels, and systematically and deeply study the construction safety of high-water-pressure sub-river tunnel and design of insulating layer for high-cold tunnel. Such reseach results are attained as follows:1. Select typical sandstone layer and alternation of sandstone-siltstone layer to carry out in-situ tracking test, and systematically test actual external water pressure and earth pressure actually acting on agent structures of sub-river shield tunnel, reveal mutual effects among agent structure, surrounding rock and water from Yangtze River, and clearly distinguish the actual stress state and structure safety of agent structure of sub-river shield tunnel.2. Apply FEM numerical simulation method to analyze single seepage field for surrounding rock and agent structure in construction period, and reveal variation laws of seepage field in the course of construction. Based on coupling theory of seepage-stress field, apply FEM numerical simulation to study the distribution and evolution laws of seepage, stress and deformation fields in construction period, and evaluate safety performances of agent structure in construction period combining with in-situ tracking test.3. Apply mathematical model of temperature field with phase-change to simulate temperature field of surrounding rock and structure in cold region tunnel so as to reveal distribution laws of temperature field and influential factor in cold-region tunnel. At the same time, apply numerical simulation of phase-change temperature field to carry out in-situ erification and numerical simulation for heat preservation effects of test sections with different heat insulation materials, structure types/thickness, reveal distribution laws of temperature field of surrounding rock and linings with and without insulating layers. Combine the results of in-situ test and numerical simulation to determine reasonable thickness of insulating layer.4. Apply coupling mathematical model of phase-change temperature field, seepage field and stress field to carry out coupling analysis of distribution laws of temperature field, seepage field and stress field, find stress conditions of tunnel structure under seasonal freeze thawing and frost heaving conditions; Combine with the in-situ test results to verify the insulating property of insulating layers with different insulation material/thickness and determine a reasonable thickness of insulating layer, and therefore provide well references for antifreezing design of analogous tunnels in cold region.For such heat-liquid-solid coupling studies facing to complex underground constructions under high water pressure and high cold conditions, it is actually significant to safety control measures of sub-river shield tunnel in construction period and design and actualization of frostresisting antifreezing measures of high-cold highway tunnel. With the rapid development of infrastructural constructions, especially the issuance of 2005 State Expressway Network Layout, such complex underground constructions as high-cold tunnel, sub-river/sub-sea tunnel, etc, take on evergrowing trends. The results about such research task can be significant references for great underground constructions at present and in the future.