为研究隧道不同渗水状态与衬砌背后水压函数关系及开裂渗水衬砌结构的承载安全，利用空气稳压的方式研制一套适用于大型模型试验的恒压恒流供水设备，实现大流量下局部水压稳定产生、分米级水头高度的控制。在室内开展1∶50大比例模型试验，研究在渗水量、裂缝开度等可直接量测的既有表观现象指标基础上，映射出衬砌背后水压大小，从而评定开裂渗水衬砌结构的承载安全。结果表明： 1）受裂缝粗糙度、迂曲度的影响，在实际工程中，开裂渗水衬砌渗流量与背后水压呈非线性变化，渗水流量(mL/s)与水头高度（m）的函数关系为y=19.69e(x/2.45)-18.06。2）开裂衬砌在水压及土压的共同作用下，渗水部位轴力会显著降低；弯矩方向发生改变，表现出“铰效应”，安全系数随渗水量的增大呈指数形式急剧下降。
To investigate the
functional relationship between different seepage states of tunnels and the
water pressure behind the lining, as well as the bearing safety of cracked and
seeping lining structures, a set of constant-pressure
and constant-flow water supply equipment suitable for
large-scale model tests is developed using stabilized
air pressure method. This equipment enables the stable generation of local
water pressure under a large flow rate and the control of water head height at
the decimeter level. Furthermore, a large-scale model
test with a scale of 1∶50 is conducted indoors to
examine and map out the magnitude of water pressure behind the lining based on
directly measurable existing apparent phenomenon indicators such as seepage
volume and crack opening degree, thereby assessing the bearing safety of
cracked and seeping lining structures. The results indicate that: (1) Affected
by the roughness and tortuosity of cracks, in actual engineering, the seepage
volume of cracked and seeping linings varies non-linearly
with the water pressure behind the lining. The functional relationship between
the seepage volume and the water head height is y=19.69e(x/2.45) -18.06. (2) Under
the combined action of water pressure and soil pressure, the axial force at the
seepage part of the cracked lining significantly decreases; the direction of
the bending moment changes, demonstrating a "hinge effect", and the
safety factor drops sharply in an exponential form with an increase in seepage
volume.
