JPS6225802B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for removing temporary supports during bridge construction work. A huge load is applied to the temporary support by the structure, and in such a case, the load becomes an obstacle to the work when removing the temporary support, making the removal work difficult. On the other hand, resin mortar is widely used as a filling material in various fields, and is also used as a filling material provided in layers on the temporary support base. Resin mortar has a sufficiently high compressive strength at room temperature, but if it is left at high temperatures of several hundred degrees for a long time, it becomes soft or brittle and tends to be easily destroyed. The present invention has been proposed based on these facts, and in the construction work of bridges, etc., electrically-conducting wires such as heating wires and reinforcing rods are placed in advance on temporary supports that temporarily receive the load of the main supports. Either by inserting an object that generates heat, or by providing a layered resin mortar part mixed with a conductive substance, and after installing the main bearing, electricity is applied to the resin mortar part to generate heat and deteriorate the physical properties of the resin mortar. This method of removing a temporary support is characterized by deforming the part to transfer the load from the temporary support to the main support, and then removing the temporary support. The purpose of this invention is to solve problems during the work of removing the support platform and to facilitate the removal work. In the present invention, as described above, an object that generates heat when energized, such as a heating wire or a reinforcing bar, is inserted into the resin mortar part for installing the temporary support stand, or
A conductive substance is mixed in, and when the temporary support is removed, heat is generated by energizing the object that generates heat by energizing as described above, or by applying a voltage and energizing the entire resin mortar part in which the conductive substance has been mixed. , the physical properties of the resin mortar deteriorate, and this deterioration deforms the resin mortar part and transfers the load from the temporary support to the main support, and the load applied to the temporary support is removed due to the deterioration of the physical properties of the resin mortar. The removal of this load and the deterioration of the physical properties of the resin mortar combine to facilitate the removal of the temporary support. At this time, only the resin mortar is heated and, as will be described later, is softened or weakened at a relatively lower temperature than the main structure, thus preventing the adverse effects of high temperatures on the surrounding main structure. be. EMBODIMENT OF THE INVENTION Below, the illustrated embodiment in which the present invention is applied to the removal work of temporary supports in bridge construction work will be described. Figure 1 shows a bridge being constructed using the extrusion method. A bridge girder block production yard 2 is prepared behind the pier 1, and bridge girder concrete is poured into 10 to 20 m lengths in the production yard 2. The continuous girder is then extruded along with the hand-stretched girder 3 at the tip, and is slid on the temporary support base 4 that constitutes a sliding support installed on the pier 1 and the temporary support (not shown) to construct a continuous girder. After the bridge girder is thus completed and the main bearings 7 are installed and fixed in the predetermined positions, the temporary supports 4 are removed, but currently the temporary supports 4 are being destroyed using a hand breaker using compressed air. , the removal work requires complicated labor and a large amount of time. In the present invention, as shown in FIGS. 2 and 3, stainless steel 8 and Teflon 9
When installing the temporary support platform 4 constructed of the above, a resin mortar 5 is injected between the bridge pier 1 and a nichrome wire 6 is inserted into the resin mortar 5, or a conductive substance is mixed in the resin mortar 5. Electricity is applied to the nichrome wire 6 to generate heat, or a voltage is applied to the entire portion of the resin mortar mixed with a conductive substance to generate heat, thereby deteriorating the physical properties of the resin mortar 5 and causing the resin mortar 5 to deteriorate. The load is transferred from the temporary support base 4 to the main support by deforming the part, and the load applied to the temporary support base 4 is removed due to the deterioration of the physical properties of the resin mortar 5. Together with the deterioration of physical properties, the removal work of the temporary support stand 4 can be easily carried out.
(See Figure 4). The composition of the resin mortar and its strength at room temperature are listed in Table 1 below.

[Table] The size of the specimen is 20mm x 20mm x 80mm. A resin mortar that has the bending and compressive strengths shown in Table 1 at room temperature can be made by applying electricity to the nichrome wire 6 shown in Figure 3 and maintaining the temperature near the nichrome wire at about 300°C for about 1 hour. As carbonization progresses, the resin mortar becomes porous, and its compressive strength drops to around 10 kg/ ^cm2 or less, making it possible to easily break it down with a reinforcing bar, or even to the side of the temporary support without breaking it. It can be removed by applying light force with a hydraulic jack, etc. As the heating element, a nichrome wire is usually used as in the above embodiment, and the voltage, current, and electrical resistance used are as follows. Heating element used: Nichrome wire (ψ=0.7mm, 2.87Ω/m) Input voltage: 140 volts Input current: 10 amperes Electrical resistance: 2.5 ohms The present invention has been described above with reference to embodiments, but the present invention is of course limited to such embodiments. The present invention is not limited thereto, and various design changes may be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the implementation status of bridge construction work to which the method of the present invention is applied, Fig. 2 is an enlarged view of the part shown in Fig. 1, and Fig. 3 is an enlarged longitudinal cross-sectional view of the part shown in Fig. 2. Figure 4 is a front view of the bridge, with the left half showing the state during extrusion construction and the right half showing the state when the sliding bearings were removed. 4...Temporary support stand, 5...Resin mortar, 6
...Nichrome wire.

Claims (1)

[Claims] 1. During the construction work of bridges, etc., objects that generate heat when energized, such as heating wires and reinforcing rods, are inserted in advance into temporary supports that temporarily support the load of the main supports, or objects that generate heat when energized are inserted into the temporary supports that temporarily support the load of the main supports, or objects that generate heat when energized are inserted into A resin mortar part is provided, and after the main support is installed, the resin mortar part is energized to generate heat to deteriorate the physical properties of the resin mortar, and the resin mortar part is deformed to transfer the load from the temporary support to the main support, A method for removing a temporary support stand, which comprises removing the temporary support stand after a certain amount of time.