热镀锌波纹管衡水波纹管厂家 力能

of the girder, we need to grout the tunnel pressure containing prestressed bars when the prestressed concrete beam is used. The corrosion of prestressed tendons and the loss of effective prestress caused by the infullness of prestressed tunnel pressure are the biggest threats to the bridge's service life, which will directly affect the overall strength and durability of prestressed bridges. Some studies have been carried out at home and abroad, most of them using nondestructive testing techniques. It mainly includes impact back wave method(I E), surface wave spectrum imaging method(SASW), ultrasonic imaging method(UT), ground penetrating ra