考虑边坡进洞高程的黄土隧道洞口段动力响应特征及抗震技术研究

In China, loess area is famous not only for strong and frequent earthquakes, but also for severe earthquake-induced geological hazards. The increasing constructions of traffic infrastructures in loess area leads to the obvious growing of quantity and scale of tunnels, while whether the tranffic system under the future earthquakes works well or not depends on the dynamic stability of the portal zones of these tunnels in loess. In recent years, one of the hot topics in tunnel and underground structure engineering is the studies about earthquake damage characteristics and anti-seimic & shock absorption techniques of mountainous tunnels. However, there is little systematic research on dynamic properties of portal zone of tunnels in loess. This project will adequately make use of and refer to the newest methods and achievements from engineering geology, loess dynamics, slope engineering, tunnel mechanics and engineering, focus on the intereactions between loess slope and portal zone of tunnels, comprehensively study the dynamic response characteristics, deformation and failure mechanism of portal zone of tunnels in loess by using the various methods, such as theoretical analysis, numerical simulation, physical model test and statistics. The key is to find out the variation law of dynamic responses of portal zone of tunnels in loess when tunnels travel across slopes with different altitude, and to understand the impact of pertal zone of tunnels on the dynamic stability of loess slope. Based on the above studies, the anti-seismic technology for portal zone of tunnels in loess would then be put forward, which also aimes to provide theoretical basis for layout of highway & railway, optimization of tunnelling altitude on slopes, options of anti-seismic and shock absorption measures for portal zone of tunnels in loess area. It is also very significant both theoretically and practically in improving the synthetical anti-seismic and hazard mitigation performance of traffic engineering in loess area, enriching and developing the research contents of earthquake-resistance of tunnel and slope engineering, and engineering geology as well.

我国黄土地区是地震活动强烈、地震地质灾害较为严重的地区。黄土地区逐渐增多的交通基础设施建设使得隧道工程的数量和规模不断扩大，而隧道洞口段的动力稳定性则决定了未来地震时交通线的通畅与否。近年来，山岭隧道震害特征和抗减震技术措施的研究成为隧道与地下工程学科的热点研究课题之一，而针对于黄土隧道洞口段动力特性的系统研究尚不多见。本项目将充分吸收借鉴工程地质、黄土动力学、边坡工程、隧道力学与工程等学科的最新研究方法和成果，以黄土边坡与隧道洞口段的相互作用为切入点，综合采用理论分析、数值模拟、模型试验和统计分析等方法手段，研究黄土隧道洞口段在强地震动作用下的动力响应特征及变形破坏机理。重点查明隧道洞口段在黄土边坡不同高程处的动力响应变化规律，同时掌握隧道洞口段对黄土边坡动力稳定性的影响，进而提出针对于黄土隧道洞口段的抗震技术,以期为黄土地区道路选线、隧道进洞高程优化和洞口段抗、减震措施选择提供理论依据

黄土地区沟壑纵横的地貌特征及交通基础设施建设的增速与完善，形成了大量桥隧相接的山岭隧道形式。由于我国黄土地区是地震高发区，考虑边坡进洞高程的黄土隧道震害特征和抗减震技术研究显得尤为重要。本课题以黄土边坡与隧道洞口段的相互作用为切入点，综合采用理论分析、数值模拟、模型试验和统计分析等方法手段，研究黄土隧道洞口段在强地震动作用下的动力响应特征及变形破坏机理,重点查明隧道洞口段在黄土边坡不同高程处的动力响应变化规律，同时掌握隧道洞口段对黄土边坡动力稳定性的影响，进而提出针对于黄土隧道洞口段的抗震技术措施。.主要完成的研究工作为：（1）山岭隧道地震动力响应及破坏特征的总结与分析；（2）考虑隧道入洞高程、仰坡角度、坡高、微结构特性、入射地震波强度等因素,对山岭隧道洞口段和黄土边坡动力响应规律的影响；（3）桥隧相接体系地震动力响应规律与特征；（4）地震作用下黄土隧道与边坡的能量分布规律及变形破坏机制研究；（5）黄土隧道抗震方法与技术研究。.主要的取得成果：.（1）入洞高程、仰坡角度、坡高、入射地震波强度的提高均会造成隧道洞口段及黄土边坡响应峰值的增大；（2）在地震作用下，孔隙率、概率熵、分维数越高的土体其加速度响应峰值及土压力响应应力差较大，土体更容易发生破坏；（3）PGA的突变与边坡响应低频成分能量占比随高程由线性到非线性的转变耦合，可作为边坡内部结构特性变化、达到稳定极限状态，即将发生整体破坏的标志；（4）给出了黄土隧道衬砌、洞口段和仰坡的抗震重点设防部位、范围及建议值, 提出了对抗震性能最不利的宏观、微观影响因素组合。