A new method for back analysis on thermal parameters of mass concrete needs
  Revised:February 28, 2002
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DOI:10.7511/jslx20035109
KeyWord:concrete,thermal parameter,back analysis,effective disturbance,contribution rate of disturbance
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Abstract:
      Traditionally, the thermal parameters for mass concrete by back analysis needs two strict conditions: one is periodically changed with surrounding temperature, another is a huge long measuring time. In order to get the thermal information of mass concrete not long after the concreting started, a quicker method is necessary. Based on the linear conduction theory of mass concrete, the relationship between temperature change of air and the response of concrete is studied. By multi linearizing the temperature process of air, and taking the advantage of superposition, a new method for the back analysis on the thermal parameters of mass concrete is presented. The continuous disturbance of air to concrete is dispersed into a series of independent unit disturbance. The temperature response of concrete to each unit disturbance may decline to a very small percent when measuring time is going on. Then, if a disturbance standard is designed in advance, the effective disturbance and ineffective disturbance of air are distinguished. Only the effective disturbance controls the final temperature of concrete, thus the thermal parameters connoted in the final temperature can be determined by optimization. The concrete specimens shaped in mold were used to carry out the test, which has performed the new method and obtained the thermal diffusivity and thermal exchange coefficient simultaneously. The way put forward needs less testing points and expends less time, so it is valuable in back design of large civil engineering.