对于大中型水库,除按防洪标准修建溢洪道外,一般还要求准备好非常溢洪措施,以便宣浅可能出现的象“75.8”型那佯的特大洪水,从而使水库的安全有更可靠的保证。当前我国采用的非常溢洪措施主要有:设置非常溢洪道(或称付溢洪道),破付坝溢洪及破主坝坝头溢洪等几种。设置非常溢洪道是最为可靠的一种非常溢洪设施、但工程量 For medium- and large-sized reservoirs, in addition to constructing flood spillways according to flood control standards, it is generally required to prepare for extraordinary spillway measures in order to declare the possible occurrence of extra-large floods such as the “75.8” type so as to ensure a more reliable guarantee of reservoir safety . At present, China has adopted a very large spillway measures are: to set the spillway (or pay spillway), break the dam overflow spill and break the main dam spillway and several other. The setting of a very spillway is the most reliable type of very overflow spillway facility but the amount of construction