块石架空围堰防渗施工技术

Seepage control technology for cofferdams with large rockcavities

土石围堰由于其材料易得、施工简便等特点得到了大量的运用,但其中的大块石容易形成架空结构,为围堰闭气施工带来困难。高喷灌浆、静压灌浆、混凝土防渗墙是比较成熟的土石围堰防渗施工方法,但对于块石架空严重的围堰和较短施工工期的防渗工程,其应用会受到动水条件、块石结构以及工期等因素的影响。本文研究了膏浆(速凝膏浆)材料的性质、施工工艺以及其与常规防渗技术的比较,并列举了膏浆技术运用的工程实例,为在块石架空围堰进行防渗施工提供了一种有效、经济的施工技术。

Embankment cofferdams are widely used in hydropower projects due to its easily obtained material and simple construction. Jet-grouting, cement grouting and concrete cutoff walls are normal tech- niques for seepage control of cofferdams. In case of utilizing huge rocks as the construction material, some large cavities may be formed in cofferdams. This would bring about difficulties in seepage control. So application of the normal techniques was confined in cofferdams with large rock cavities or with short construction period due to several factors, such as, flowing water, rock-structure and available construction time, etc. This paper introduces the quick control of embankment cofferdams and discussed coagulating paste-slurry technique to be used for seepage its characteristics and relevant workability. A comparison is made for this method with the normal seepage control techniques. A few practiced examples of pasteslurry technology application were given. They show that the paste-slurry technique is one of the effective and economical method for cofferdams with large rock cavities.