基于低模量高阻尼橡胶的地铁盾构隧道自适应隔震机理研究

A large number of metro shield tunnels have been built in China, many of them are located in high-intensity earthquake zones and under serious threat of earthquake disaster. Furthermore, metro shield tunnels are usually under complex geological conditions and there are many joints between the segments, thus resulting in their poor seismic performance. Seismic isolation is an effective technique to mitigate earthquake damage. This study combines the low modulus, high damping, and self-adaptive mechanical characteristics of the novel low modulus high damping rubber to investigate the self-adaptive isolation mechanism of metro shield tunnel based on the this material. Firstly, a low modulus high damping rubber is developed through the blending modification theory of rubber material and optimization of the ratio of additives. Secondly, a series of material tests are conducted on low modulus high damping rubber to study the influence of large strain and loading rate on its mechanical properties. On the basis of experimental results and theoretical derivation, a self-adaptive mechanical model of low modulus high damping rubber is established allowing the consideration of large strain and high loading rate. Finally, considering the structural characteristics of the shield tunnel and the self-adaptive mechanical performance of the low modulus high damping rubber, an accurate seismic analysis model of the isolated shield tunnel is established. The seismic response of the isolated shield tunnel is evaluated to validate its isolation effect and further investigate its self-adaptive isolation mechanism based on the low modulus high damping rubber. This study provides a novel seismic isolation material and theoretical model for the metro shield tunnels, and it involves important scientific significance and engineering value.

我国已建地铁盾构隧道中有大量位于高烈度地震区，面临严重的震害威胁。而且地铁盾构隧道穿越的地层条件复杂，管片间存在大量接头，导致其抗震性能较差。隔震技术是防震减灾的有效手段，本项目结合新型低模量高阻尼橡胶的低模量、高阻尼和自适应力学特性，研究基于该材料的地铁盾构隧道自适应隔震机理。首先，基于橡胶的共混改性理论和优化添加剂配比，研究出低模量高阻尼橡胶。其次，针对低模量高阻尼橡胶开展一系列力学试验，研究大应变和加载速度对低模量高阻尼橡胶力学性能的影响规律。基于理论推导和试验数据，建立涵盖大应变和高速加载状态的低模量高阻尼橡胶自适应力学模型。最后，考虑盾构隧道的结构特征和低模量高阻尼橡胶的自适应力学性能，建立准确的盾构隧道隔震分析模型，验证盾构隧道的隔震效果，进一步探明基于低模量高阻尼橡胶的隧道自适应隔震机理。本项目的研究为地铁盾构隧道提供了新的隔震材料和理论模型，具有重要的科学意义和工程价值。

橡胶作为一种典型的超弹性材料，柔软轻质，能承受较大变形，具有良好的缓冲隔震性能，同时还兼具较好的气密性和防水性，适合盾构隧道的施工。因此，设置橡胶隔震层有望成为未来隧道减震减灾的技术手段之一。本项目的研究内容聚焦在以下三方面：第1，基于橡胶的共混改性理论和填充改性理论，研究出具有低模量和高阻尼特性的新型橡胶。第2，研究低模量高阻尼橡胶的强非线性力学特性，建立其较精确的力学模型。第3，分析基于低模量高阻尼橡胶的盾构隧道隔震性能，并针对橡胶层位于隧道隐蔽部位的情况，探索相应的质量管理方法。本项目的主要成果有：第1，以天然橡胶和氯化丁基橡胶为原料，提出了制备低模量高阻尼橡胶的工艺流程。基于橡胶添加剂试验的结果，分析了各类添加剂对橡胶的影响，研究结果表明：选用粒径较小的炭黑，以及增大树脂的用量有利于降低橡胶的剪切模量。同时，适当增加炭黑用量，可以显著改善橡胶的阻尼性能。第2，针对低模量高阻尼橡胶开展了一系列力学试验，特别是对橡胶进行了不同加载速度下的大变形剪切试验，并由此分析了低模量高阻尼橡胶的非线性力学行为。在力学模型方面，首先，基于试验数据构建了低模量高阻尼橡胶精确适用的应变能函数。其次，基于应变能函数和连续介质力学理论，建立了其较精确的力学模型以较好地模拟橡胶的强非线性特性。第3，建立了盾构隧道的隔震分析模型，并通过数值方法验证了盾构隧道的隔震效果。此外，借助探地雷达扫描了隧道隐蔽部位，初步研究了橡胶层的质量管理办法和检测手段，并通过试验方法分析了几种常见介质对橡胶层质量检测效果的影响。