通透肋式拱梁隧道结构荷载设计计算方法探讨

DISCUSSION ON DESIGN AND CALCULATION METHOD OF STRUCTURAL LOADS FOR PERMEABLE TUNNEL WITH RIBBED ARCH BEAM

The permeable tunnel with ribbed arch beam，which is a new type of tunnel structure，is analyzed. The geological environmental conditions and structural characteristics of this tunnel are expounded；and the concept of the design load standard for which the relaxation of the pressure caused by the surrounding rock failure in the limit state for this kind of non-symmetric half-dark tunnel structure is presented. By the numerical simulation study of the pattern and scope of tunnel surrounding rock failure，the basic failure modes of this tunnel can be concluded as which the vault slope rock slip along a ramp through the arch of the foot to form a wedge，and the size of the angle between the sliding failure surface and the horizontal plane determine the range of surrounding rock failure. On this basis，the structural load design and calculation model of the permeability tunnel with ribbed arch beam is established with theoretical analysis of the derivation，and compared and analyzed with the actual monitoring data and the numerical simulation results of construction conditions. The results show that the calculated internal forces distribution of this model can better reflects the variation of the internal force of tunnel structure，have a reliable safety margin，so as to provide a practical and effective design calculation method for the same type of half-dark tunnel structure section design and evaluation of long-term stability.