Study On Crack-proof By Temperature Control Of Lining Concrete Of Hydraulic Tunnel In Construction Period

As for hydraulic tunnel lining concrete, thermal stress is one of important factors that cause concrete cracks, due to the heat of hydration of cement in the construction period. Thermal cracks, especially cutting through concrete lining, are very harmful to lining structures. At the same time, since hydraulic tunnel is constructed underground, the structure is in danger and very difficult to restore once such structure cracks are brought about.In China and overseas, deep research has been done and increasing attention has been paid to massive concrete engineering on the surface. On the other side, research on lining concrete engineering under the earth is carried out simply and rather insufficiently, requirements from temperature control of it are rare, regulations involved are not strict, and practical examples are few as well. Therefore, either specific criterions or integral and reliable examples for reference are wanted in the design of temperature control of underground concrete engineering in our country at present. So, making a particular research for the design of temperature control of the hydraulic tunnel lining concrete is very critical.This paper calculates the factors of the original temperature field of rock before the lining is placed, placement of lining in subsection, temperature rise of concrete due to hydration being the function of time in the Period of Constructing, etc. At first it takes advantage of powerful computational function of ANSYS, simulates actual construction process, and directly figures out temperature developing process of lining concrete in the Period of Constructing; and then, it calculates the increment of concrete stress with time and the creep based on elastocreeping theory and superposition principle respectively, works out the thermal stress of concrete at every period of time in the way of combination of Visual Basic and ANSYS; and finally reaches ultimate stress consisting of creep. By this way, this paper computes three-dimension concrete temperature field and temperature stress field in the period of construction of water-conveying tunnel's concrete lining of the Three Gorges Project Permanent Ship Lock, simulating actual construction process, calculating the influence of creep on thermal stress, and further researches the temperature control measure of water-conveying tunnel's concrete lining of the Three Gorges Project Permanent Ship Lock and the relation of tunnel shape and lining concrete thermal stress. Then some suggestions, which can be consulted for the design and construction of underground concrete engineering, are reached.