隧底溶洞处理后衬砌的受力分析

隧道底部溶洞处理时，存在填充物弹性模量大于围岩弹性模量现象，影响衬砌受力状态，可能导致裂缝的产生。针对这一问题，以温克尔弹性地基梁理论为基础，对溶洞处理后衬砌的内力和位移进行计算，并结合数值模拟结果进行对比分析。主要研究结论如下： 1）溶洞填充物对衬砌起支撑作用，引起溶洞与围岩交界处附近出现较大剪力和弯矩； 2）溶洞段衬砌拉应力增大较快，应加强此段衬砌结构的配筋，加设抗弯和抗剪钢筋，提高结构抗拉及抗剪能力，达到抑制裂缝产生的目的； 3）确保溶洞填充物尽量与围岩弹性模量相近，交界处介质的弹性模量连续递变，以改善溶洞段衬砌的不利受力状态。

Analysis on Lining Stress of Tunnel with Filled Karst Caves under its Floor

The elastic modulus of the materials filled in the karst caves under the tunnel floor is smaller than that of the surrounding rock,which affects the stress of the lining and,in the end,causes lining cracks.In the paper,the stress and displacement of the lining of a tunnel with filled karst caves under its floor are calculated on basis of Winkle elastic foundation beam theory and the calculation results are compared and analyzed on basis of numerical simulation results.Conclusions drawn are as follows：1） The materials filled in the karst caves play a supporting role for the tunnel lining and causes large shear force and bending moment at the boundary between the karst caves and the surrounding rocks; 2）The tensile stress of the lining at the karst cave positions increases rapidly,therefore,the structural reinforcement of the lining at these positions should be strengthened,i.e.,anti-bending steel bars and anti-shear steel bars should be added to improve the tensile and shear capacity of the structure so as to avoid cracks ; 3） Efforts should be made to ensure that the elastic modulus of the materials filled in the karst caves is close to that of the surrounding rock as much as possible to improve the stress state of the lining at the karst cave positions.