极高烈度地震区不同矢跨比曲线隧道地震响应分析

Seismic response analysis of curved tunnels with different rise-span ratios in extremely high intensity seismic area

中文关键词: 曲线隧道  极高烈度  矢跨比  地震响应  数值模拟

英文关键词: curved tunnel  extremely high intensity  rise-span ratio  seismic response  numerical simulation

中文摘要:

      依托跑马山隧道极高烈度以及其曲线段平面线形复杂的特点，提出矢跨比(α)的概念对其进行分类，并采用数值模拟方法建立不同矢跨比曲线隧道在地震作用下的数值模型，研究曲线隧道在极高烈度地震区的地震响应．结果表明:与直线隧道相比，曲线隧道在地震作用下的相对变形具有明显区段性，按照变形增长快慢，可以将其分为增长段(0~300 m、900~ 1 200 m)和平稳段(300~900 m)．其中增长段相对变形增长快，且x方向水平相对变形(ΔUx)较大，而平稳段相对变形几乎不变，但是y方向水平相对变形(ΔUy)较大．曲线隧道在增长段的相对变形速率和塑性应变随着矢跨比的增大而增大，其中相对变形速率、塑性应变的最大增长幅度分别达到14倍、3倍，同时平稳段与增长段的加速度差值也增大．综合考虑不同矢跨比曲线隧道相对变形、塑性应变以及加速度响应的变化规律，α=0.1，0.2的曲线隧道的地震响应与直线隧道更为接近，而α=0.3，0.4的曲线隧道的地震响应更具曲线特性，因此在进行抗震设计时需要重点考虑．

英文摘要:

      Based on the extremely high intensity of Paomashan tunnel and the complex plane alignment of its curve sections, the concept of rise-span ratio (α) is put forward to classify it, and the numerical model of curved tunnels with different rise-span ratios under earthquake action is established by numerical simulation method. The seismic response of curved tunnel in extremely high intensity seismic area is studied. The results show that: In comparison to straight tunnels, the curved tunnel exhibits distinct sectional variations in relative deformation under the earthquake action. The curved tunnel can be categorized into a growth section (0-300 m and 900-1 200 m) and a stable section (300-900 m) based on the rate of deformation expansion. Notably, the relative deformation in the growth section experiences a rapid increase and higher horizontal relative deformation in xdirection (ΔUx). While that in the stable section remains nearly constant, albeit horizontal relative deformation in y direction (ΔUy) at a higher magnitude. The relative deformation rate and plastic strain of the curved tunnel in the growth section escalate with an increase in the rise-span ratio. Specifically, the maximum increase amplitudes in relative deformation rate and plastic strain are 14 times and 3 times, respectively. Furthermore, there is an increasing disparity in acceleration between the stable and growth sections. Analyzing the variation patterns of relative deformation, plastic strain and acceleration response for curved tunnels with different rise-span ratios, it is observed that the seismic response of curved tunnels with α=0.1, 0.2 is closer to that of straight tunnels, while the seismic response of curved tunnels with α=0.3, 0.4 is more curvilinear, necessitating consideration in seismic design.