材料置换法改善拱坝应力集中的数值模拟

通过体型优化设计可使拱坝坝体以受压为主，当拉应力超过混凝土的极限抗拉强度后，由于应力重新分布的作用，使局部区域的拉应力转变为压应力.以某拱坝为例，通过置换拉应力较大区域的混凝土为低弹模混凝土，使坝体以受压为主，充分发挥混凝土抗压强度高的特点，改善坝体的应力状态，提高坝体的强度安全性.采用有限元ANSYS10.0为平台，以坝高100 m的拱坝为计算模型，利用直接耦合法计算拱坝应力，得到拱坝在温升和温降工况下的应力分布状况，主要分析了对坝体拉应力不利的温降工况；采用低弹模混凝土置换坝体拉应力值比较大的区域，使置换区域的拉应力减小约50%，而压应力增加的幅度不明显，可以改善拱坝坝体拉应力集中现象，提高了拱坝的安全性.

Numerical simulation of arch dam stress concentration improved by a material replacement method

In the shape optimization design of the arch dam， it is necessary to make the concrete in a large scale under compression. When the tensile stress exceeds the ultimate tensile strength of the concrete， local area under tension may shift to compression by the action of the stress redistribution. The concrete having low elastic modulus can be replaced in the region under higher tension to decrease the peak tension stress. By this way， the stress state and the safety factor of the arch dam have been improved. An arch dam with the height of 100 m is taken as an example in the study. The stress states under conditions of temperature rise and temperature drop are analyzed by the direct coupling method of the ANSYS10.0. It is clear that much attention should be paid under the temperature rise condition. After replacement of concrete having the low elastic modulus in the region under higher tension， the peak tension stress decreases to 50%， however， there is no remarkable increase in compression stress at the replacement region. Hence， this method can reduce the stress concentration and improve the safety of the arch dam.