基于位移反分析的小湾拱坝稳定性评价

小湾拱坝坝体裂缝在大坝分阶段实际蓄水后开裂扩展的可能性以及裂缝对坝体应力、位移和坝体稳定性的影响，对大坝安全至关重要。通过对小湾拱坝坝体施工过程及坝体内部温度裂缝的模拟，基于多点监测资料进行非线性位移反演分析，得到符合实际的材料力学参数，进而对坝体进行三维非线性仿真计算研究，以预测坝体在下一阶段蓄水以及最终蓄水后的稳定性。结果表明，该反演分析方法反演得到的参数合理准确，预计的位移结果可靠、精度较高，能很好地对拱坝安全性进行评价；仿真分析预测成果与坝体后期蓄水后的实际监测成果和地质力学模型试验成果吻合良好，在正常水载下，坝体整体变形符合拱坝变形一般规律，同时裂缝发生开裂扩展的可能性很小；裂缝对坝体整体影响不大，对局部有影响，大坝极限开裂状态与无缝坝类似，坝面开裂均是由表面产生裂缝向内部发展，而不是由内部裂缝引发。

RESEARCH ON STABILITY ESTIMATION OF XIAOWAN ARCH DAM BASED ON DISPLACEMENT BACK ANALYSIS

The effects of cracking of Xiaowan arch dam on the possibility of cracking propagation，and on the stress，displacement and stability should be considered seriously after phased realistic impounding. The basic principle is three-dimensional nonlinear numerical computation by simulation of the construction process of Xiaowan arch dam and the cracks in the dam based on reasonable material parameters which are obtained by the multipoint displacement back analysis on the basis of the monitoring data. The result indicates that the parameters obtained by the displacement back analysis are reasonable and accurate；and the prediction of the dam displacement is of high precision，which can provide a good stability estimation of the dam. The predicting results fit well with the monitoring data and the results of geomechanical model test. The global deformation of the dam accords with the general pattern；and the possibility of crack propagation is very small under the normal water load. The effects of cracking on the global stability of the dam are very small；and the limit state of the dam is similar to that of no cracking working condition. Both of them crack from the surface to the inside，instead of cracking from the internal cracking.