HIGH SLOPE EXCAVATION AND ANCHORINGON THE LEFT BANK OF THE XIAOWAN HYDROPOWER STATION

摘要

The research in this paper is essentially focused on the high slope and cumulus excavation andrnanchoring construction on the left bank of the Xiaowan Hydropower Station. The Xiaowan dam ranks thernfirst in height (the maximum height of 292m) among the concrete double curvature arch dams underrnconstruction in China. Since the excavated slope on the left bank is as high as 700m and its embankment slotrnexcavation height reaches 292m, its construction is characterized by higher excavation elevation differencernand intensity, stricter requirements on vibration by blasting, higher quality of foundation excavation for therndam embankment slot and many difficulties in longer tendon installation. By way of widespread applicationrnof rock muck turning over, presplitting blasting, bench relayed millisecond sequential detonating in deeprnboreholes, the excavation schedule and quality have been effectively guaranteed. The difficulties in deep holerndrilling and tendon installation at high slope cumulus have been overcome by developing and utilizing ofrneccentric casing apparatus, variable-diameter casing and concentric casing methods. As the traditional groutrninjection for the tendons installed in the cumulus and fractured rock mass is not workable, the technique ofrngeotextile wrapping against leakage and corrosion, developed after tests and studies, has been adopted tornhandle the hot potato. The successful and speedy implementation in the high slope excavation and anchoringrnconstruction has achieved tremendous economic benefits and will be of active importance in similar projectsrnapplication in future.