| A big technical problem for mass concrete stuctures during pouring is how tocontrol crack expansion . Releasing steam 'heat from the mass concrete structures while solidifying leads to produce the temperature change and contraction. They cause the corresponding stresses which are Ihe main factors to from crack in the mass concrete structures. It is obvious for crack to destroy the completeness , anti. water and water-tolerant behavior of the structures and to become a hidden peril of the stuctures. Thus, crack control must be considered while a mass concrete strcture is in coostruction.The paper presents a solution method for the transient temperature field, in which the finite element method or the finite difference method is used to get discrete strcture , and the finite difference method is used to get discrete time in order tO simplify the transient thermal conductive equations as a set of linear equations as a set of linear equalions at different moment. Separating Ihe whole process of reduction in temperature into several time sections in which change in temperature is to be assumed as linear the total disparity in temperature including the disparity due to equivalent contraction can be obtained.As practical engineering examples the poper has shown the analyses oncrack control in two mass concrete structures by use of the procedure mentionedabove, in which the transient temperature fields were obtained from the results bythe finite difference method or the temperature curves measured in construction. The results are the same as happened in engineering . No crack happened inpractice and in catculation. The involving date calculated could be used by thedesigners and technicians. The paper also mentioned some measures on crackprevention.
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