为确保盾构在“气压模式”下掘进及在带压开舱作业时控制舱内气压的稳定，在分析刀盘正面土体、开挖间隙周边土体、盾尾注浆和螺旋输送机4个区域的气压损失范围基础上，改进Krabbe公式并考虑渗透系数、舱内压强、地层变化等影响因素，提出空气损失量Q的半经验半理论计算方法。将计算方法应用于实际工程，通过对空气损失量最大断面进行灵敏度分析，主要结论如下： 1）舱内压强与空气损失量呈二次正相关，工程范围内气压的增加会导致一定的空气损失； 2）空气损失量最大的断面为地层突变处，通过分析该断面的灵敏度，可以对盾构配备的空气压缩机功率进行合理的判断。
The stability of air pressure in shield chamber during
tunneling under "air pressure mode" and chamber opening under
pressure should be guaranteed. Hence, the air pressure loose zones in 4 areas
of soil in front of cutterhead, soil around the excavation gap, grouting area
in shield tail and screw conveyor are analyzed, the Krabbe formula is improved,
and based on which a semiempirical and semitheoretical calculation method of air loss Q is proposed by considering the permeability coefficient, earth
chamber pressure and soil variation. The calculation method is applied to
practical engineering, and the following conclusions are drawn by sensitivity
analysis of the crosssection with the largest air
loss: (1) There is a quadratic positive correlation between chamber pressure
and air pressure loss, and the increase in air pressure within the scope of the
project will result in a certain volumn of air loss. (2) The crosssection with the largest volumn of air loss locates in formation
abrupt change area, and by carrying out sensitivity analysis on this crosssection, the power of air compressor equipped on shield can be
reasonably judged.
