高碾压混凝土坝裂缝成因及防治措施研究

碾压混凝土坝不同程度存在裂缝,降低了混凝土坝的安全度。以某碾压混凝土坝为例,根据实测的裂缝资料就该坝的裂缝成因进行了系统分析,并提出了防治措施。研究表明:施工时层面长间歇和汛期过流冷激是该坝产生裂缝的主要原因。因此,施工过程中应避免长间歇,若不可避免应加强长间歇层面的温控措施,如加强保温、控制层厚等。过流缺口由于冷激产生的裂缝,可通过表面流水或中期冷却提前将过流面以下一定高程混凝土冷却至某一目标温度值,以减小由于冷激造成的温差过大。

Study on crack causation of high roller-compacted concrete dam and its prevention measures

On roller-compacted concrete （RCC） dam，cracks exist to some extent，which can lower the safety degree of the concrete dam. By taking a RCC dam as a case，the crack causation of the dam is systematically analyzed herein according to the measured cracking data，and then the relevant prevention measures are proposed as well. The study shows that long inter-layer pause and cold shock from water flow during flood season during the construction are the main causes of the occurrences of cracks on the dam. Therefore，the long pause must be avoided during the construction，and if it is unavoidable，the temperature control measures，e.g. enhancing insulation，thickening control layer，etc.，must be strengthened for the inter-layer of long pause. For the cracks caused by the cold shock from flow notch，the concrete on a certain altitude under the flow surface can be cooled to a target temperature value in advance through surface flow or medium-term cooling，so as to decrease the excessive temperature difference caused by cold shock.