剪切波作用下盾构隧道地震效应的拟静力分析方法研究

针对均质土层中圆形盾构隧道在水平剪切波作用下的地震响应分析问题,在获得隧道周边自由场剪切应力的基础上,利用弹性中心法和空洞复变函数,给出了深埋盾构隧道在土层结构界面滑移和不滑移情况下的解析分析公式;并建立相同条件的等效刚度数值分析模型和考虑接头效应的有接头分析模型进行对比。研究表明:等效刚度拟静力法与等效刚度数值法所获得的剪切地震波作用附加弯矩、附加轴力分布形态及其最大值发生位置都具有良好的一致性;在三种方法获得的附加弯矩和附加轴力当中,等效刚度拟静力法最大,等效刚度数值法次之,有接头数值法最小;土层结构界面滑移相对不滑移而言,附加轴力偏小、附加弯矩偏大;等效刚度拟静力法结果偏于安全,公式简便,考虑界面滑移时更加接近实际,故可推荐考虑滑移条件的等效刚度拟静力法作为深埋圆形盾构隧道的抗震设计方法,并与常时荷载静力分析结果叠加后进行配筋设计。

QUASI-STATIC ANALYSIS METHOD FOR SEISMIC EFFECT OF SHEAR WAVES ON SHIELD TUNNEL

Based on the distribution of free-field shear stress around the tunnel, utilizing the elastic center method and the cavity complex variable function, this paper presents an analytic formula for the seismic response of circular deep-buried shield tunnel, where slip and non-slip contacting conditions are imposed to the soil-structure interface respectively and the tunnel is subjected to horizontal shear waves in homogeneous soil. Furthermore, a comparison is made between the equivalent stiffness numerical analytic model and the analytic model considering the effect of joints, showing that the equivalent stiffness quasi-static method and the equivalent stiffness numerical method generate reasonably consistent results in the distribution of shear-wave induced bending moment and axial force as well as the position where the induced bending moment and the axial force reach the maximum. The equivalent stiffness quasi-static method generates the maximum results, followed by the equivalent stiffness numerical method and the analytic model considering the effect of joints. Moreover, considering soil-structure interface slip results in a smaller induced axial force and a larger induced bending moment. In conclusion, the equivalent stiffness quasi-static method takes soil-structure interface slip into consideration, which coincides with practical condition and presents higher safety coefficient and formula simplicity. Consequently, it can be suggested as the anti-seismic design approach for deep-buried circular shield tunnel, and the superposition of the results of constant load static analysis can be conducted to determine the reinforcement design.