偏压隧道洞口段复合套拱力学性能研究

Study on the Mechanical Properties of the Compound Umbrella Arch in the Unsymmetrically Loaded Tunnel Entrance

为全面掌握偏压隧道洞口段复合式套拱的力学性能,对林屋隧道进口洞口段的复合套拱的桩底应力、桩身应力、钢架应力及拱顶下沉等进行监测,并应用ANSYS有限元软件对复合套拱的受力情况进行模拟分析.结果表明:在偏压地形情况下,复合套拱桩基底应力分布不均匀,极易造成基底不均匀沉降;偏压隧道洞口段复合套拱受力情况复杂,桩身底部易产生拉应力,拱肩、拱顶部位易产生较大压应力,不利于整体的稳定;复合套拱的两侧边桩承受较大的弯矩和轴力,对于提高隧道洞口整体稳定性有极大作用;偏压隧道洞口段左、右套拱受力差异较大.应针对各自的受力特点,对偏压复合套拱进行结构优化,以充分发挥复合套拱的优势,提高其经济效益.

For a comprehensive analysis of the mechanical properties of the compound umbrella arch in the unsymmetrically loaded tunnel entrance, through monitoring the stress on the bottom of the pile, pile stress, steel stress and dome subsidence of the compound umbrella arch of Linwu Tunnel entrance section, ANSYS finite element software is applied to simulating the force of compound umbrella arch. The results show that under the bias terrain, the stress of the pile bottom is nonuniform which will cause the nonuniform settlement. The situation of the stress is very complicated, the tensile stress is produced in the pile bottom, and the compressive stress is produced in the arch foot and the vault, which is not conducive to the stability of the overall umbrella arch. The piles on the both sides of the umbrella arch bear the larger bending moment and axial force, which improve the stability of the tunnel entrance. The both sides＇ forces of the umbrella arch have a large difference. The structural optimization of unsymmetrically compound umbrella arch should base on their respective force characteristics in order to give full play to the advantages of the composite umbrella arch and improve its eco-nomic efficiency.