Abstract: The combination of dam heel concrete and bed rock, together with the closure of cracks in the bed rock near contact area always exert great influence to seepage and structural safety of arch dams. The research shows that dam heel concrete of the arch dam on wide valley is likely to crack, and avoidance of harmful temperature and water level is of importance to crack prevention. As well, tangential unsymmetrical deformation of arch dam is helpful in dam performance evaluation. When it is found that unsymmetrical deformation is divergent, dam body and dam foundation may be damaged which calls for high attention. Comprehensive diagnosis with monitoring data and counter-measures should be carried out to prevent accidents.

摘要： 拱坝坝踵混凝土与基岩之间的结合状况，以及接触面附近基岩内裂隙的闭合状况，直接关系到拱坝渗流和结构的安全，工程实例和分析表明，宽谷拱坝坝踵比较容易出现张开现象，避免水位和温度的不利组合，对防止坝踵张开具有重要作用。拱坝切向不对称变形趋势是判断拱坝整体工作状况是否正常的重要依据，若不对称变形呈发散型增大变化，很可能坝体、坝基已遭受损坏，需引起高度重视，应结合其它监测信息综合评判，采取必要措施，防止灾害性事故发生。