地下管幕结构组合板作用机理及横纵向刚度的匹配机制研究

Traditional underground excavation methods used in practical engineering have the following shortcomings; complicated construction procedure, instability issues and difficulty in controlling ground settlement. A new pipe-roofing method is proposed in this project to mitigate these issues by pipe-jacking the steel pipe into the soil. The pipes are connected by flanges and bolts in transversal direction. Concrete is poured into the pipes as well as the gap between two pipes to shape a flat-roofed underground structure, after which the soil under the pipe-roofing structure is excavated. This new method can greatly improve the transversal stiffness and bearing capacity of the structure. However, the mechanism between longitudinal steel pipe concrete and transversal connection, physical matching of transversal and longitudinal stiffness still needs theoretical support. The laboratory test and numerical modeling of pipe-roofing structure composite slab is conducted based on the transversal bending property of pipe-roofing structure. First, the bending performance test of pipe-roofing structure composite slab under uniaxial bending is conducted to obtain the longitudinal bearing capacity and stiffness of composite slab. Second, the bidirectional loading mechanism and deformation property of composite slab is studied. The impact of span ratio, thickness of steel slab, space between adjacent pipes, diameter of steel pipe and other sensitive parameters on bearing capacity and deformation of composite slab is investigated. This research will provide theoretical support on engineering design on the physical matching of pipe-roofing structure transversal and longitudinal stiffness.

目前地下工程现有的暗挖施工方法工序复杂、安全性差以及沉降难以控制。本文所研究的管幕工法是用顶管法把钢管顶入土中，钢管横向采用翼缘板和螺栓进行连接，然后在管内和管间灌注混凝土，形成平顶的地下管幕支护结构，然后进行土方开挖。该管幕结构横向刚度和横向承载力得到了很大提高，但是纵向钢管混凝土和横向连接的相互作用机理，以及横向和纵向刚度的合理匹配仍缺乏理论支撑。本项目在已取得的管幕结构横向抗弯性能的基础上，以管幕结构组合板室内试验结合数值分析方法展开。首先，进行管幕结构组合板单向受力的抗弯性能试验，得出组合板纵向的承载力和刚度计算公式；其次，研究管幕结构组合板双向受力机理及变形性能，得到管幕结构的跨度比、钢板厚度、相邻钢管间距、钢管直径等敏感参数对管幕结构组合板的承载力和变形的影响规律。研究结果为管幕结构横向和纵向刚度合理匹配的工程设计提供理论支持。

STS（Steel tube slab）管幕工法是用顶管法把钢管顶入土中，钢管横向采用翼缘板和螺栓进行连接，然后在管内和管间灌注混凝土，形成平顶的地下管幕支护结构，然后进行土方开挖。目前对于STS管幕结构的纵向钢管混凝土和横向连接的相互作用机理、横向和纵向刚度的合理匹配、以及STS管幕组合板的极限承载力设计方法缺乏理论支撑。本课题在已取得的管幕结构横向抗弯性能的基础上，以管幕结构组合板室内试验结合数值分析方法展开。首先通过管幕结构纵向抗弯性能试验，得到管幕结构纵向破坏特征及受力机理，并提出纵向抗弯承载力及刚度计算方法。之后开展管幕结构组合板双向抗弯性能试验，研究管幕结构组合板双向受力机理及变形性能，并基于上述试验结果建立考虑钢管混凝土相互作用的数值计算模型确定合理参数，并利用该模型研究管幕结构组合板破坏的全过程以及参数敏感性，得到管幕结构的钢管厚度、翼缘板厚度、螺栓直径、相邻钢管间距、管间混凝土高度与组合板长宽比等敏感参数对管幕结构组合板的承载力和变形的影响规律。最后，基于双向受力特性，提出管幕结构双向承载力及抗弯刚度计算方法。此外，基于当前研究结果又对纯钢结构组成的新型管幕结构的抗弯性能进行了初步探索。.项目执行期间，研究成果获得了辽宁省科技进步二等奖，获授权发明专利7项，发表期刊论文19篇（SCI收录11篇，EI收录7篇）。