隧道压力拱边界统一判定方法及其空间演化特征

Unified boundary determination method of pressure arch in tunnels and its spatial evolution characteristics

为分析隧道开挖后围岩的稳定性,首先,对比不同方法,确定压力拱内边界、外边界的异同,建立压力拱边界的统一判定方法;然后,分析不同开挖方法对压力拱的影响;最后,提出隧道三维压力拱边界判定方法,揭示三维压力拱不同开挖步下演化特性与空间形态。结果表明:压力拱随着开挖步推进而逐渐扩大;采用中隔墙(CD)法开挖压力拱最小;由于工作面的空间约束作用,三维压力拱较二维的小,压力拱形态由小喇叭状逐渐变化,高度与宽度逐渐增大。在实际施工中,可采用分部开挖方法进行过程控制,并利用掌子面的空间约束作用,保证隧道施工安全。

In order to analyse stability of surrounding rock after tunnel excavation,firstly,differences and similarities of inner and outer boundaries of pressure arch under different methods were investigated,and a unified method to determine arch boundaries was defined.Then,influence of different excavation methods on pressure arch was compared.Finally,a method to determine boundaries of three-dimensional pressure arch of the tunnel was proposed and evolution characteristics and shape of the arch were obtained under different excavation steps.The result shows as excavation step progresses,pressure arch gradually expands,which will be the smallest for Center Diaphragm(CD)method.The three-dimensional pressure arch range is smaller than that of two-dimensional one,and its shape gradually changes from a small trumpet due to spatial constraints of the tunnel face,while its height and width also gradually increase.During tunnel construction,segment process control can be achieved by adopting subsection excavation method,and space constraint of the tunnel face can be utilized to ensure safe construction.