大净高跨线桥快速拆除技术

针对既有大净高跨线桥拆除时存在的效率低、能耗高、安全性差和污染重等问题,以武汉四环线跨青郑高速K7+700高架桥(16+2×22+16)m钢筋混凝土连续刚构桥,梁下净高9.8m]为背景,提出车载移动支撑式分段提吊下放快速移除方法,并进行了施工设备的研制。研制的设备主要由移动运输机构、提吊支架和提吊下放机构组成。首先在路外场地将提吊支架拼装在移动运输机构上,形成车载移动支撑;然后移动运输机构自动驾驶至待拆梁体两侧,与提吊下放机构拼接,完成设备组拼;随后预提吊梁段,将其自重转移至该设备;最后依次切割梁体、分段提吊下放、移运,实现快速拆除。实践表明,在桥下既有高速半封闭条件下,该方法可实现大净高跨线桥安全快速拆除,缩短工期,降低能耗和污染,经济效益显著。

Rapid Demolition Techniques for Overpass with Large Net Clearance

The demolition of existing overpasses with large net clearance often faces the problems of low efficiency,high energy consumption,low safety insurance and heavy pollution.In this case,the K7+700 viaduct crossing the Qingzheng Expressway on the Fourth Ring Road in Wuhan is taken as the study background.The bridge is a reinforced concrete continuous rigid-frame bridge with spans of 16,2×22 and 16 m,and the net clearance below the bridge is 9.8 m.It was proposed that the viaduct be dismantled section by section using the truck-mounted movable supporting system,and the construction equipment were researched and developed.The equipment is mainly composed of the movable transportation system,lifting frames and hoisting and lowering system.First,the lifting frames were assembled on the movable transportation system off the bridge site,to form the truck-mounted movable supporting structure.Then,the movable supporting structure was automatically moved to the two sides of the section of the viaduct waiting for demolition,and connected with the hoisting and lowering system to complete the assembly of the equipment.The beam section was pre-hoisted to transfer its self-weight to the movable supporting structure.At last,the body of the viaduct was cut into sections for hoisting,lowering,removal and transportation,to realize the rapid demolition.The demolition practice demonstrates that the method can help realize the safe and rapid demolition of the overpass with large net clearance when the existing expressway is semi-closed.The method features short operation time,lower energy consumption and pollution as well as significant economic benefits.