JPH0296022A - Device for settling bridge pier - Google Patents

Abstract

PURPOSE:To make smooth settlement and easy adjustment for tilting possible by providing an ejection tube, having a plurality of ejection nozzles, to an outer peripheral shoulder of a caisson that is provided to the underside of a bridge pier, and by supplying compressed air independently to each of the ejection tube that is divided into a plurality. CONSTITUTION:To the underside of an elliptic cylindrical bridge pier 1, a caisson 3 having a cutting edge 2 is provided, and to an outer peripheral shoulder 4; i.e. friction cut, at the outer periphery of the caisson 3, an ejection tube 6 is provided and a number of ejection nozzles 5 are provided thereto. The ejection tube 6 is divided, for example, into four sections and each of the divided ejection tube 6 is connected, through each one of air supply tubes 8, to each of compressors 9 installed aboveground. At settlement, the bridge pier 1 is sunk with deadweight of the caisson 3 and with actuation of compressed air that is supplied from the compressors 9 and ejected through the ejection nozzles 5. When the caisson 3 tilted, the tilting can be restored by suspending the air supply to the section of the tilted side. Thereby, settlement of the bridge pier and adjustment for tilting of the caisson can be managed easily.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a pier sinking device for a pier installed on soft ground such as a river.

(Prior Art) Generally, piers for mounting bridges and elevated roads are constructed of concrete or reinforced concrete. In areas where the ground is weak, such as rivers, these piers are erected by sinking deep into the ground. Normally, the caisson construction method is used to sink a bridge pier, in which a pier with a roughly circular cutout at the bottom is pushed downward by heavy machinery as it sinks, and then another pier is built on top.

(Problems to be Solved by the Invention) In the conventional caisson construction method, as the cutting edge of the caisson sinks deeper, the soil and water pressure applied to the caisson increase, making it difficult to sink and making the sinking work difficult. It was also extremely difficult to adjust the structure to straighten it if it tilted and sank.

Therefore, the present invention has been made based on the above-mentioned problem, and an object thereof is to provide a pier sinking device that can reduce the earth pressure applied to the caisson and facilitate the sinking, as well as easily adjust the inclination. There is.

[Structure of the Invention (Means for Solving the Problems)] The present invention provides a jet pipe having a plurality of jets 1 with the jet direction directed outward on the outer peripheral shoulder of a caisson provided at the lower part of a pier. The jet pipe is divided into a plurality of parts to provide an air supply pipe for sending air, and a plurality of compressors are provided to each independently send high-pressure air to the air supply pipe.

(Function) When the compressor is driven while the caisson is sinking to send high-pressure air to the blowout pipe via the air supply pipe, the high-pressure air reduces the earth pressure directed outward from the blowhole of the caisson, which prevents the caisson from sinking. Moreover, if the caisson is tilted, the tilt can be easily adjusted by blowing air to the divided jet pipes as appropriate or stopping the blowing of air.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. In Figures 1 to 3, 1 is a substantially elliptical cylindrical pier;
A caisson 3 having a cutting edge 2 is provided at its lower part, and the pier 1 is erected so that the caisson 3 is buried in the excavated ground. An ejection pipe 6 having a large number of ejection holes 5 formed over the entire circumference of the outer circumferential shoulder 4 is attached to an outer circumferential shoulder 4 which is a so-called flex 2 john cut provided by the outer circumference of the caisson 3. The ejection hole 5 has its ejection direction directed upward. Also,
The ejection pipe 6 is divided into four sections A, B, C, and D as shown in FIG. 2, and the same sections are communicated with each other. An air supply pipe 8 is provided in communication with the ejection pipe 6 in each section via an elbow 7, respectively. These air supply pipes 8 are buried within the caisson 3, and their upper ends extend to the upper part of the pier 1 and are connected to each of the four compressors on the ground. In addition, in order to install these air supply pipes 8 and ejection pipes 6, after arranging the air supply pipes 8 in the formwork of the caisson 3 and pouring concrete, immediately attach the ejection pipes 6 to the outer peripheral shoulder 4,
After the air supply pipe 8 and the ejection pipe 6 are connected and the concrete hardens, the ejection hole 5 is formed so as to face directly above.

In the device of the present invention configured as described above, in order to sink the pier 1, the caissons 3 are lowered by the weight of the pier 1 or by pushing downward from the top of the pier 1 with a heavy machine. When caisson 3 sinks deeply, earth pressure and water pressure are applied toward caisson 3, making it difficult for caisson 3 to sink. In this case, when 1.4 compressors 9 are driven to send high-pressure air to the jet pipes 6 of each section through the air pipes 8, the high-pressure air is jetted downward from the jet holes 5 and directed toward the caisson 3. Because the earth pressure is weakened, Caisson 3 will be less likely to sink. In addition, if the caisson 3 tilts during this subsidence, if high-pressure air is blown to the jet pipe 6 in the section on the tilted side,
High earth pressure is applied to the caisson 3 on this side, and high pressure air is blown out from the jet pipe 6 on the opposite side, so the tilt is corrected so that the earth pressure decreases and the caisson 3 sinks smoothly. Therefore, in this embodiment, the ejection pipe 6 is divided into four sections, each of which receives high-pressure air independently, so that the inclination of the caisson 3 can be easily corrected by sending or not sending high-pressure air in appropriate combinations. can be done.

Although one embodiment of the present invention has been described in detail above, it can be modified as appropriate within the scope of the gist of the present invention.

For example, although the pier 1 is shown as being approximately elliptical, it may be approximately cylindrical. Further, although the ejection pipe 6 is divided into four sections, the number of sections can be set as appropriate. Further, the direction of ejection is not limited to upward, but may be directed outward.

[Effects of the Invention] As detailed above, according to the present invention, a caisson is provided at the lower part of a pier, and a large number of ejection holes are provided along the outer peripheral shoulder of the caisson and the ejection direction is directed outward. an air supply pipe that divides the ejection pipe into a plurality of parts and sends air;
To provide a pier sinking device that reduces earth pressure applied to a caisson, allows smooth sinking, and facilitates adjustment of inclination by including a plurality of compressors that independently feed high-pressure air into the air pipes. Can be done.

6. Ejection pipe 8... Air pipe 9. Compressor

Claims (1)

[Claims] A caisson installed at the bottom of the pier, an ejection pipe installed along the outer circumferential shoulder of the caisson, and having a large number of ejection holes with the ejection direction facing outward, and this ejection pipe divided into multiple parts to send air. A pier subsidence device comprising an air pipe and a plurality of compressors that independently feed high-pressure air into the air pipe.