Investigation Of Temperature And State Of Stress On The Factory Prefabrication Immersed Tunnel

As the river sea-crossing bridge construction development, it is used widely because ofimmersed tunnel’s navigation ability, minor impact on the environment. But immersed tunnelvolume is big, mass concrete temperature field and temperature stress all have weaknesses.Because of the temperature field and temperature stress’s distribution of complexity, and theimmersed tunnel may be affected by many factors, therefore, it is difficult to obtain theanalytical solution of the real in practical projects. This thesis mainly aims at the Hong Kong,zhuhai and macau bridge immersed tunnel precast factory process, reasonable finite elementsimulation the whole process of prefabricated pipe section, study the hydration heat of thetemperature field and temperature stress, and simulation analysis local position of the localpushing stress. The main researches are as follows:(1) The thesis summarizes the basic concept and basic process of pipe section factoryprefabrication, the difference between pipe section’s factory prefabrication process and thetraditional precast technology of pipe section, the system of mass concrete temperature fieldand thermal stress of the basic theory.(2) The thesis Simulates the process of immersed tunnel factory prefabrication, and gets inthe different environment condition and different stages of the hydration’s heat temperaturefield, temperature stress, specifically researches on the hydration heat peak stage（dismantlingformwork pipe section and pushing）of the temperature field of concrete and temperaturestress, studies the relationship between concrete structure and the temperature of the largestnumerical in this stage in the different environment condition, and the relationship betweenthe stress of concrete and the allowable stress.(3) The thesis simulates the process of immersed tunnel factory prefabrication, gets thedifferent environment condition and different construction phase of pushing position’s localstress, and looks for the rule of local stress with the change rule of the external environment,researches local pressure segement abilities by deducing the local stress of theory and finiteelement simulation of the actual, and researches the causes of" the arch of stress " in aroundof the local stress’s scope and whether it produce harm to the structure.(4) The thesis gets crack ratio figure of the segement through the simulation of constructionsatge, contrasts the different environment condition and different construction stage oftensile stress and allowable stress, analyses the reason of that there will be "temperature crack", but it ultimately won’t appear in the process of segement prefabrication. And it isobserved the effect on the crack by the change of environmen.On the basis of the researches mentioned above, some crucial conclusions areacquired asfollows: the Hong Kong, zhuhai and macau bridge immersed tunnel pipe section’s factoryprefabrication process is order and feasible in the construction progress at present in the year,it’s safe for dismantling formwork at three days and pushing segement at four days inconcrete casting pipeline section. In the Hong Kong, zhuhai and macau bridge immersedtunnel prefabrication process has not adopted in pumping concrete, and use less collapsbillityconcrete, the latter’s hydration reaction heat generation of relative is also lower, and thespecial structure form of the pipe section is good for the heat of hydration, so the whole pipesection in factory prefabrication process conditions is completely feasible.