上软下硬地层小净距双线矩形隧道减震措施研究

Study on Seismic Mitigation Measures for Two-lane Small-clearance Rectangular Tunnels in Upper Soft and Lower Hard Strata

为了提高上软下硬地层中小净距双线矩形隧道的抗震性能,依托某小净距双线矩形隧道工程,利用有限差分软件FLAC^(3D),分别研究了半包、垫层、全环减震层的减震效果。研究结果表明:半包减震层可以使横向位移减小29.9%,拱顶位移减小22.9%,最大、最小主应力减小8.0%、8.1%,最大剪应力减小22.5%,最小安全系数提高44.2%;垫层减震层可以使横向位移减小23.5%,拱顶位移减小13.7%,最大、最小主应力减小10.8%、1.3%,最大剪应力减小1.4%,最小安全系数提高5.0%;全环减震层可以使横向位移减小19.5%,拱顶位移减小20.6%,最大、最小主应力减小22.5%、4.7%,最大剪应力减小4.8%,最小安全系数提高30.4%。综上,施设半包减震层的减震效果最优,因此推荐本工程采用此措施进行抗震设防设计。

In order to improve the seismic performance of two-lane rectangular tunnels with small spacing on upper soft and lower hard strata,this paper relies on a two-lane rectangular tunnel with small spacing project and uses the finite difference software FLAC^(3D) to study the seismic mitigation effects of the half-cover,cushion and full-cover damping layer.The results show that the half-cover damping layer can reduce the lateral displacement by 29.9%,the vault displacement by 22.9%,the maximum and minimum principal stresses by 8.0%and 8.1%,the maximum shear stress by 22.5%,and the minimum safety factor increases by 44.2%;The cushion damping layer can reduce the lateral displacement by 23.5%,the vault displacement by 13.7%,the maximum and minimum principal stresses by 10.8%and 1.3%,the maximum shear stress reduces by 1.4%,and the minimum safety factor increases by 5.0%;the full-cover damping layer can reduce the lateral displacement by 19.5%,the vault displacement by 20.6%,the maximum and minimum principal stresses by 22.5%and 4.7%,the maximum shear stress by 4.8%,and the minimum safety factor increases by 30.4%.In conclusion,the seismic mitigation effect of the half-cover damping layer is optimal,so it is recommended to adopt this measure for seismic fortification design in this project.