陡坡隧洞明满交替流成因及改善措施

Causes and Control Measures of Mixed Free-Surface-Pressure Flow in Steep-slope Tunnel

山区河道陡坡隧洞易于形成的明满交替流,会对隧洞产生空化空蚀、振动、冲击破坏。基于陡坡隧洞的模型试验研究成果,对陡坡隧洞明满交替流的影响因素及其改善措施进行了研究。分析了明满交替流形成的主要影响因素,包括洞前相对淹没深度H/a、隧洞体型(包括隧洞底坡、进口顶部体型、洞高、洞长、是否有转弯段、闸门井等)、进口引渠布置以及由上述因素形成的吸气漩涡、闸门井吸气影响等。综合考虑工程地形、地质、工程运用要求以及安全经济等因素,可采取消涡措施、消除闸门井吸气措施、隧洞进口顶部体型优化与选择以及洞高和洞长优化等措施,改善陡坡隧洞的明满交替流现象。

The mixed free-surface-pressure flow which is easily formed in steep-slope tunnels results in cavitation e- rosion, vibration and impact damage. On the basis of model test data of steep-slope tunnels, the influencing factors and the control measures of mixed free-surface-pressure flow in steep-slope tunnel is researched. It＇ s found that the main influencing factors include relative submerge depth H/a, tunnel shape （bottom slope, inlet top shape, tunnel height, tunnel length, bending section, gate shaft）, inlet approach channel configuration and the consequent air suction swirl and air intake in the gate shaft. According to the terrain condition, geological condition, project func- tion, operation safety and economic factor, measures as follows can be adopted to control the mixed free-surface- pressure flow in steep-slope tunnel ： vortex suppression, air intake suppression in gate shaft, and optimization of in- let top shape, tunnel height and tunnel length.