JOURNAL OF YANGTZE RIVER SCIENTIFIC RESEARCH INSTI ›› 2013, Vol. 30 ›› Issue (8): 40-45.DOI: 10.3969/j.issn.1001-5485.2013.08.0;2013,30(08)

• Orignal Article • Previous Articles     Next Articles

Causes and Control Measures of MixedFree-Surface-Pressure Flow in Steep-Grade Tunnel

LI Xue-hai1, LI Heng2, SHI Jiao-hao1   

  1. 1.Hydraulics Department, Yangtze River Scientific Research Institute, Wuhan 430010, China;
    2.Changjiang Institute of Survey, Planning, Design and Research,Changjiang Water Resources Commission, Wuhan 430010, China
  • Received:2013-05-03 Revised:2013-08-13 Online:2013-08-13 Published:2013-08-13

Abstract: The mixed free-surface-pressure flow which is easily formed in steep-grade tunnels results in cavitation erosion, vibration and impact damage. On the basis of model test data of steep-grade tunnels, the influencing factors and the control measures of mixed free-surface-pressure flow in steep-grade 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 arrangement and the consequent air suction swirl and air intake in the gate shaft. According to the terrain condition, geological condition, project function, operation safety and economic factor, measures as follows can be adopted to control the mixed free-surface-pressure flow in steep-grade tunnel vortex suppression, air intake suppression in gate shaft, and optimization of inlet top shape, tunnel height and tunnel length.

Key words: steep-grade tunnel, influencing factor, mechanism of formation, control measures

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