复杂环境下水工隧洞管片衬砌-围岩间接触力学行为与水力交换机制研究

The combined bearing mechanism of segmental lining and surrounding rock is the key factor to the safety of hydraulic tunnel, in which the mechanism of contact behavior and hydraulic exchange between lining and surrounding rock is the kernel scientific subject. In this project, the indoor loading test of lining segment is designed to study the stress and deformation of the lining segment, as well as the evolutions of the contact area and the opening aperture of the joint surfaces between lining segments. The calculation model of segmental lining structure will be improved based on the method to estimate the opening aperture. With acoustic detection and drilling sampling, the spatial distribution characteristics of compactness and grouting saturation of the pea gravel under the complicated construction environment will be investigated. With the help of mechanics and seepage tests, the temporal and spatial evolutions of material properties of pea gravel under dry and wet environment are going to be studied, and the method for evaluating mechanical parameter and permeability coefficient of pea gravel can be developed. Based on the observed data of engineering prototype, the dynamic evolutions of opening aperture and contact pressure at the interfaces, including the lining-pea gravel interface and the pea gravel-rock interface, will be investigated. Further speaking, the characterization method of contact behavior between lining and surrounding rock can be improved. The numerical model, which considers the cohesive and contact/slip characteristics at the interfaces, will be established so that the contact behavior between lining and surrounding rock can be investigated. Moreover, the calculation method of flow capacity of lining gap will be improved, and the combined calculation model composed of these three different kinds of materials is going to be developed. On the basis of the above issues, the mechanism of contact behavior and hydraulic exchange between lining and surrounding rock can be investigated, and the bearing mechanism of segment-lined hydraulic tunnel under HM coupling environment will be revealed.

管片衬砌-围岩联合承载特性是影响隧洞安全的关键，衬砌-围岩间接触力学行为和水力交换机制是其核心科学问题。本项目拟开展衬砌管片室内加载试验，研究管片受力变形特征、接缝接触面积与开度演化规律，建立接缝开度计算方法，完善衬砌管片结构计算模型；采用声波探测技术和钻孔取样方法，研究复杂施工环境下豆砾石密实度与灌浆饱和度的空间分布特征；开展豆砾石力学与渗透试验，研究干/湿环境下豆砾石材料性能的时空演变规律，建立豆砾石力学和渗透参数取值方法；结合原型观测数据，研究管片-豆砾石-围岩间接缝开度/接触压力动态演化规律，完善衬砌-围岩间接触力学行为表征方法，构建体现衬砌-豆砾石-围岩交界面粘结与接触/滑移特征的数值计算模型，研究衬砌-围岩间接触力学行为；完善管片接缝过流能力计算方法，构建衬砌-豆砾石-围岩组合计算模型，研究衬砌-围岩间接触力学行为与水力交换机制，揭示HM耦合环境下管片衬砌水工隧洞承载机理。

引调水工程隧洞由于水头相对较低，且隧洞长度较大，通常设计中多采用圆形断面和TBM施工方式，管片衬砌是其主要的衬砌形式。围岩-豆砾石-衬砌管片（螺栓）共同构成承载主体，三者如何联合受力共同发挥作用是工程成败的关键。本项目针对复杂外部环境下的管片衬砌与围岩的变形协调关系与水力交换机制开展研究，采用理论分析、室内试验、数值模拟与原型观测相结合的综合研究方法方法，研究衬砌-围岩间的接触力学行为和水力交换机制。研究结果表明：在内水压力作用下，衬砌与围岩间的摩擦接触可以导致管片中部的拉应力水平较高，适当降低两者间的摩擦系数有利于保证管片的完整性；豆砾石连接围岩与衬砌管片，其渗透性有利于消减管片衬砌内较高的水压力，灌浆后的豆砾石可以加强管片间的止水防渗效果，足够的密实度和充分灌浆可以保证基本的弹性模量量值，可以给管片衬砌提供足够良好的支持，并保证管片衬砌结构与围岩的变形一致性；豆砾石在环向上的刚度一致性可以给管片提供均匀的径向支撑作用，需要优化和提升环向上的豆砾石回填和灌浆的均匀性。对于有内外水交换限制的分离式管片衬砌，往往在管片和不透水钢管之间设置排水板，作为软垫层结构，其铺设范围以及其材料参数是控制分离式衬砌实现其功能设计的基础，研究表明铺设范围一定情况下，综合参数d/E（厚度/弹模）取值应更有目标导向。相关研究成果可为隧洞衬砌结构全过程的安全问题提供有效支撑，保证了隧洞的运行安全，为管理与运行方提供强有力的保障。