针对较大形变压力作用下挤压性围岩隧道断面形状优化的问题，在时速200 km客货共线铁路隧道建筑限界的基础上拟定单线和双线铁路隧道断面形状，通过结构安全性评价，提出不同变形等级条件下单线和双线铁路隧道较经济、安全的断面形式。研究结果表明： 1）随着变形等级的增加，围岩压力显著增大，结构安全系数明显降低，从建筑限界出发拟定的最经济的隧道断面不能满足结构安全性要求。2）拱脚及墙脚是隧道结构受力薄弱部位，通过优化断面曲率实现拱部与边墙、边墙与仰拱的圆顺衔接，可有效改善结构受力状态，提高结构安全性。3）对于单线铁路隧道，Ⅰ级变形条件下推荐采用单线断面A（与常规单线铁路隧道断面相衔接），Ⅱ级变形条件下推荐采用单线断面B（在单线断面A的基础上对断面曲率进行优化），Ⅲ、Ⅳ级变形条件下推荐采用单线断面E（圆形）。4）对于双线铁路隧道，Ⅰ、Ⅱ级变形条件下推荐采用双线断面C（在常规双线铁路隧道的基础上优化断面曲率），Ⅲ、Ⅳ级变形条件下推荐采用双线断面E（圆形）。5）工程实践中，隧道断面优化应综合考虑结构安全、区段衔接和施工便利性，综合确定各区段隧道断面形状； 在Ⅳ级变形条件下，应加强注浆加固，并采用多层支护及应力释放等技术措施保证隧道结构安全。
To optimize the
crosssection shape of squeezed surrounding rock tunnels under large
deformation pressure, the crosssection shapes of
single-and doubletrack railway tunnels are determined
based on the construction clearance of passenger and freight railway tunnel
with a speed of 200 km/h. Economic and safe crosssection
types of single-and doubletrack railway tunnels under
various deformation levels are proposed through structural safety evaluation.
The conclusions are drawn as follows: (1) With an increase in deformation
level, the structural load increases and the structural safety coefficient
decreases evidently. The most economical tunnel crosssection
proposed based on the construction clearance cannot meet the structural safety
requirements. (2) The arch and wall feet are the weak parts of the tunnel
structure. By optimizing the curvature of tunnel crosssection,
the smooth connection between arch and sidewall and that between sidewall and
inverted arch can be realized, thus effectively improving the stress state of
the structure and the structural safety. (3) For single track tunnel: singletrack A crosssection type (connected with
the normal singletrack tunnel section) is recommended
for grade I deformation, singletrack B crosssection type (optimized crosssection
curvature based on singletrack A crosssection) is recommended for grade II deformation, and singletrack E crosssection (circular) is
recommended for grades III and IV deformation. (4) For doubletrack tunnel: doubletrack C crosssection type (crosssection curvature
optimized on the basis of conventional doubletrack
tunnel) is recommended for grades I and II deformation, and doubletrack E crosssection (circular) is
recommended for grades III and IV deformation. (5) In engineering practice, the
crosssection type should be comprehensively optimized
considering structural safety, zone connection, and construction convenience.
Under grade IV deformation condition, strengthened grouting reinforcement,
multilayer support, and stress release should be
conducted to ensure the safety of the tunnel structure.
