碾压混凝土拱坝设人工短缝的应力释放及止裂作用

大仓面碾压混凝土拱坝横缝少，整体性好，仓面准备工作量少，浇注工艺简化，施工速度快，省水泥和温控措施，但施工期内外温差约束强，运行期均匀温降及温差应力大。拱结构研究表明：在上游坝肩拉力区设人工折缝，将折缝缝端置于低应力区，下游面拱冠设径向短缝，可以大大减少或消除温度和水压引起的拉力；从近缝两侧有限元节点位移差直接求得缝端应力强度因子，和缝端止裂措施组合韧性比较，可以保证人工构造缝的稳定。该设计已用于碾压混凝土工程，实测表明在超高水位下运行时人工短缝张开小于1mm，止裂措施后实测应变小于37个微应变，止裂效果好，人工缝保持稳定。

Effect of artificial short joints on stress relaxation and cracking control in RCC arch dam

The effect of artificial short joints on stress relaxation and cracking prevention is studied by means of FEM. The calculated stress of the arch dam show that the tension region caused by thermal variation and hydraulic pressure can be greatly minimized or avoided by setting artificial joints to tension region in upstream abutment and downstream arch crown with the end of joints located at low stress region. Stress intensity factor at the end of the joint can be obtained directly from the displacement difference of the finite element nodes on both sides of the joint. This cracking control measure is applied to engineering practice of RCC arch dam and the effectiveness is verified by prototype observation.