【正文】 為重要。本文結(jié)合工程實(shí)例 ， 根據(jù)隧道所處 地質(zhì)條件、工期要求 ， 通過比選提出了可達(dá)到快速施工和節(jié)省施工成本目的的最佳施工方案。 (4) costeffectiveness. Based on these four principles, through the construction of research and demonstration program to select the following two programs to pare the selection of the construction. a single type of wall construction plan The program39。 a single type of wall。s main construction steps and measures are as follows: (1) ranging from crossdoublearch tunnel into two singlehole, change the formula for the separation wall, the first line of oneway rightforward construction of the tunnel. (2) three arch tunnel in the wall to make the first nonShi lining, according to singleline working condition through. (3) the right line of largesection doublearch tunnel wall construction method adopted in accordance with CRD. (4) The return line is in accordance with the right line of the opposite side of the construction sequence of construction. Adoption of this program is in fact a oneway in accordance with the construction of two methods, pared with the previous one, after the program has the following advantages: (1) reduction of the construction process to speed up the convergence process conversion. (2) reduce the construction difficulty, shortening the construction cycle. (3) reduce the construction costs and improve Economic efficiency. (4) change a single type of wall to separate the wall, pletely solved the structure of doublearch tunnel waterproofing defects. (5) The threearch tunnel in the latter pArt of the construction hole, equivalent to largespan rock tunnels reserved for the core is conducive to both sides of the doublearch tunnel construction safety (Table 1). Section 3 threearch construction plan Rightline direct access to three doublearch tunnel, the Support parameters to the original designs for grating erection of the whole ring, according to design the whole ring of shotcrete, and enhance the bolt at the wall vault settings (return right side Tong Line Construction method), wall construction in the tunnel when you need to get rid of Office, located at a vertical grill joints strengthened beam. Strict control of excavation footage of each cycle, grid spacing of / Pin. Weak in the wall excavation using millisecond blasting program (conditional maximize the use of static blasting programs), minimize the wall rock and the lining of the tunnel has been disturbed, to ensure construction safety. The pletion of excavation in the wall immediately after the secondary lining. After the pletion of construction of the wall in wall voids of the backfilling, plus jack supports. The side of the construction is pleted, carry out the other side of the wall construction. When both sides of the wall construction is plete, in a timely manner on both sides of a singlehole tunnel secondary lining, and then proceed to threearch tunnel excavation and lining of the middle of rock. Construction, special attention should be three arch tunnel in the wall at the settlement and convergence deformation, such as the unusual phenomenon, an immediate reinforcement. 4 construction of the force structure of Behavior Analysis Across the range of the doublearched wall canceled, changed to separate the wall, in the domestic urban underground railway engineering has not yet been a similar engineering design and construction experience, there is no such tunnel structure design, and therefore the structure is safe, as well as the course of construction conversion process of construction is safe, the program will be the focus of the study. Application of ANSYS finite element software for mon procedures ranging from crossarch tunnel numerical simulation, using stratigraphic structural model of the structure of the tunnel by the force and deformation analysis (Figure 1, Fi gure 2, Figure 3). The scope of the horizontal direction taken by force along the direction of the tunnel crosssection to crosshole 3 times the limit, taking the top of the vertical direction to the surface, the bottomhole span to 3 times the limit, unit model uses the DP formation of elasticplastic material entity, the tunnel Lining with elastic beam element simulation,