围岩类型及衬砌厚度对水工隧洞地震动力响应的影响分析

以分析水工隧洞在地震激励作用下的变形破坏机制为目标,针对不同围岩类型和衬砌厚度条件下水工隧洞位移变化,根据地下结构抗震计算理论,选取合理的材料参数和模型边界条件,使用ANSYS建立了某水工隧洞的三维有限元模型,对其施加水平和竖向地震激励,应用瞬态分析法计算了隧洞结构模型在不同围岩类型和衬砌厚度下的水工隧洞动力响应。结果表明,在相同衬砌厚度下,随着隧洞围岩强度的降低,水平位移和竖向位移受影响的程度有明显的区别,即水平位移越来越大,竖直位移无明显规律可循;在相同的围岩强度下,水工隧洞并不会随着衬砌厚度的增加而趋于稳定,在Ⅲ类围岩的情况下,水工隧洞的位移随着衬砌厚度的增加而越来越大,Ⅴ类围岩下改变衬砌厚度对水工隧洞的位移几乎没有影响。因此,合理的设计围岩类型和衬砌厚度,可以既满足水工隧洞抗震性能要求,又能够降低工程造价。研究结果对合理设计隧洞衬砌厚度、增强抗震性能具有参考价值。

Analysis on impact from surrounding rock and lining thickness on seismic dynamic response of hydraulic tunnel

By taking analyzing the deformation damage mechanism of hydraulic tunnel under the effect of seismic excitation as the study objective，a 3-D finite element model for a hydraulic tunnel is established with ANSYS by selecting reasonable material parameters and model boundary conditions for the displacement variations of hydraulic tunnel under the conditions of various surrounding rock types and lining thicknesses in accordance with the relevant seismic calculation theory for underground structure，and then the horizontal and vertical seismic excitations are applied to it，and the dynamic responses of hydraulic tunnel under the conditions of various surrounding rock types and lining thicknesses of the model for the tunnel structure are calculated with the method of transient dynamic analysis. The result shows that under the condition of the same lining thickness，the impacted degrees of both the horizontal displacement and the vertical displacement are clearly distinguished along with the decrease of the strength of the surrounding rock in the tunnel. The horizontal displacement becomes more and more large，while there is no any obvious laws for the vertical displacement to be followed with. Under the same strength of surrounding rock，the hydraulic tunnel is not to tend toward stable along with the increase of the lining thickness. Under the condition of the surrounding rock of Class III，the displacement of the hydraulic tunnel is more and more large along with the increase of the lining thickness，while there is almost no any impacts on the displacement of the hydraulic tunnel from the change of the lining thickness for the surrounding rock of Class V. Therefore，the reasonable design of the surrounding rock type and the lining thickness can not only meet the requirement of the seismic performance of hydraulic tunnel，but also can lower the relevant construction cost. The study result has reference value for the reasonable design of the thickness of the tunnel lining for enhancing its seismic performance.