马蹄形预制初期支护结构生产及试验技术研究

传统的初期支护施工安全性低、劳动强度大、环境污染严重、质量难控制，为改善现有的作业环境，提高施工质量和进度，提出了一种马蹄形预制初期支护结构。从结构设计方案、预制方式、拼装方法以及试验实例4个方面做了详细介绍，并对关键技术进行了阐述，结果表明：型钢混凝土结构分块设计时要兼顾受力状态、加载模式、结构吊运等各方面因素，同时还要考虑型钢加工难度，单根型钢的弯曲半径不宜超过2种；柔性模板与刚性背楞有效组合，能够预制各类异形结构，材料也可重复利用，经济性良好；预制初期支护结构在2.3倍设计荷载时裂缝开始发展，在3.1倍设计荷载时出现连接节点失效，试验证明其承载能力满足工程需求。

Study on Production and Test Technology of Horseshoe Prefabricated Initial Support Structure

Traditional initial support construction has characteristics of low safety, high labor intensity, serious environmental pollution and difficult quality control. In order to improve the existing working environment and improve the construction quality and progress, a horseshoe prefabricated initial support structure is proposed. The structural design scheme, prefabrication method, assembly method and test examples were introduced in detail, and the key technologies were described. The results show that: in the block design of steel reinforced concrete structure, all factors such as stress state, loading mode and structural lifting shall be taken into account, at the same time, the processing difficulty of section steel shall be considered, the bending radius of single section steel shall not exceed 2. Flexible formwork and rigid back ridge are effectively combined, which can prefabricate all kinds of special-shaped structures, and the materials can also be reused with good economy. The cracks of the prefabricated initial support structure begin to develop when the design load is 2.3 times, and the connection joint failure occurs when the design load is 3.1 times. The test shows that its bearing capacity meets the engineering requirements.