JPS589240B2 - earth pressure gauge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an earth pressure meter, and more particularly, it measures the earth pressure acting on segments used as shoring or primary lining when excavating using the shield method or tunnel polling machine. It is related to earth pressure gauges.

Conventionally, various earth pressure gauges such as a diaphragm type earth pressure gauge and a hydraulic balance type earth pressure gauge have been proposed as earth pressure meters for measuring the earth pressure acting on a segment, but these have the following drawbacks.

(1) The pressure receiving area is 10 to 20 cm in diameter (area 78 to 31 cm)
4cm2), it is difficult to make uniform contact with the ground, and the measured values are relatively affected by the installation conditions of the soil pressure meter, making it impossible to sense accurate soil pressure.

(2) At the time of installation, a jig is attached to the segment of the target object in advance, and after assembly on site, the segment is pressed against the ground via the jig and attached, which takes time and effort.

(3) Measured values are easily affected by installation conditions, pressing pressure, etc.

(4) A hydraulically balanced type can make a large earth pressure gauge, but it is extremely expensive, takes a long time to manufacture, and is not practical.

(5) Since the soil pressure gauge is additionally attached to the segment as a foreign object, care must be taken when handling it, and if the external shape of the segment changes due to the installation of the soil pressure gauge, the segment assembly and shield Directly affects tunnel excavation work such as propulsion.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, and to be able to accurately measure the earth pressure acting on a segment.
To provide an earth pressure gauge which has a simple structure, can be manufactured in a short period of time and at low cost, can be easily attached to a segment, does not hinder tunnel excavation work by being attached, and can measure the physical pressure at any time during tunnel construction. It is in.

The earth pressure gauge according to the present invention has an opening in the skin plate of the segment, and a back surface of the skin plate surrounding the opening.
A frame having a flange protruding inward from the entire inner peripheral surface is fixed, a rubber plate is placed on the tunnel side of the flange, a pressure receiving plate made of a flat steel plate is connected with bolts, and a strain gauge is installed approximately in the center of the pressure receiving plate. , filling the opening on the ground side of the rubber plate with a filler that transmits earth pressure until it is flush with the skin plate, and aligning the surface with the surface of the filler layer,
An earth pressure meter characterized by a plurality of strip-shaped sliding plates fixed to a segment or frame, and in which the strain of the pressure receiving plate due to earth pressure is measured with a strain gauge, and the earth pressure is calculated from the strain value. be.

EMBODIMENT OF THE INVENTION Hereinafter, the earth pressure meter of this invention is demonstrated based on the drawing of an Example.

FIG. 3 is a bottom view of the embodiment of the soil pressure meter of the present invention, and FIGS. 1 and 2 are the I-1 line and ■-I line in FIG. 3, respectively.
It is a sectional view taken along the line I.

In FIGS. 1 to 3, 1 is a segment main body.

In the example, segment 1 is made of steel.

The skin plate 2 of the segment 1 is provided with an opening 1a.

The size of the opening 1a is made large enough to apply accurate pressure to the pressure receiving plate.

Generally, providing an opening across the ribs provided in the segment body 1 reduces the strength of the segment body, so the size is set to be about 50×50α.

The shape is generally rectangular or circular.

In the illustrated embodiment, the opening 1a is square.

A square frame 4 is fixed to the back surface of the skin plate 2, surrounding the opening 1a.

In the illustrated embodiment, the frame 4 is not directly fixed to the skin plate 2, but is fixed to the original rib 3 of the segment that is integrated with the skin plate 2, and to the original rib 3 and the skin plate 2 at necessary locations by welding or the like. It is fixed to the skin plate 2 via new ribs 3.

The frame 4 is provided with a flange that protrudes inward from the entire inner peripheral surface.

A pressure receiving plate 5 made of a flat steel plate is bolted to the tunnel side of the flange of the frame 4 with a rubber plate 6 in between.

The rubber plate 6 is for waterproofing and load distribution.

Furthermore, the rubber plate 6 prevents the stress of the segment body from being introduced into the pressure receiving plate 5.

Instead of the rubber plate 6, the pressure receiving plate 5 may be coated with rubber.

The rubber plate 6 also serves to protect the strain gauge attached to the ground side of the pressure receiving plate 5.

Strain gauges 7 are attached to both sides of the pressure receiving plate 5 approximately at the center, and lead wires 8 are led out from each strain gauge 1.

The opening 1a of the pressure receiving plate 5 on the ground side, specifically, the opening 1a of the rubber plate 6 on the ground side, is filled with filler 9 until it is flush with the skin plate 2.

The filler 9 needs to be a material that transmits the earth pressure acting on the opening 1a to the pressure receiving plate 5.

Furthermore, it must be watertight and must be able to prevent groundwater from entering into the opening 1a.

Examples include hard rubber-like synthetic resins such as polyurethane, pitch, and the like.

A plurality of strip-shaped sliding plates 10 are arranged on the surface layer of the filler layer 9, and both ends of the sliding plates 100 are fixed to the frame 4.

The sliding plate 10 may be directly fixed to the segment body 1 (skin plate 2 or rib 3).

The sliding plate 10 is oriented in the direction of propulsion of the segment body 1, with its surface aligned with the surface of the filler layer 9.

In this earth pressure gauge, the earth pressure acting on the opening 1a of the segment main body 1 is transmitted to the pressure receiving plate 5 via the filler layer 9 and the rubber plate 6, causing the pressure receiving plate 5 to become strained and strain gauge 7.
detects the strain degree of the pressure receiving plate 5, and earth pressure is calculated from the strain value.

In this way, this upper pressure gauge is provided integrally with the segment main body 1, and the pressure receiving area can be increased, so that earth pressure can be accurately measured.

Further, the inside of the opening 1a is filled with a water-impermeable filler 9,
The intrusion of groundwater is prevented, accurate earth pressure is transmitted to the pressure receiving plate 5, and the filler layer 9 is protected by the sliding plate 10, so when the segment body 1 is propelled into the ground during tunnel excavation work. will not be damaged.

Furthermore, since the opening 1a is filled with the filler 9 up to the same level as the skin plate 2, water leakage from the tail packing can be prevented when the segment body 1 is pushed out from the shield tail. .

In the examples, the case where the segments are made of steel is described, but segments other than steel, such as cast iron,
The structure of the present invention can be applied to concrete segments as well.

That is, in the case of a cast iron segment, since a skin plate is present, the structure can be exactly the same as in the case of a steel segment.

In the case of concrete segments, an opening may be provided in advance and a pressure receiving plate mounting frame may be embedded in the segment when manufacturing the segment.

As described above, the earth pressure gauge of the present invention has a structure in which the pressure receiving part is provided integrally with the segment, and has other characteristic structures, so that many effects as described below can be expected.

(1) The pressure receiving area can be made approximately 50crILX 50cmL or 50crrt in diameter, which is 10 to 20 times larger than conventional methods, improving measurement accuracy and increasing the adaptability of earth pressure measurement. It can respond to a wide range of changes in mountain soil conditions, tunnel construction conditions, etc.

(2) It is easy to install, and does not require attachment or detachment especially when assembling segments, so there is no problem with tunnel construction, and earth pressure can be measured at any time according to each stage of tunnel construction.

(3) Since the shape and dimensions of the earth pressure gauge are compatible with those of the segment, the conditions for generating earth pressure can be made the same as those of the segment itself. This makes it possible to perform accurate measurements.

(4) Since the structure is simple, it can be manufactured in a short delivery time and is inexpensive.

(5) Sensitivity can be freely selected by appropriately selecting the thickness of the pressure plate and the strain gauge.

(6) The rubber plate attached to the outside of the pressure plate maintains watertightness, prevents the stress of the segment body from being introduced into the pressure plate, and further disperses the concentrated force acting from the ground, resulting in measurement results. reliability can be improved.

(7) The sliding plate provided on the outside of the filler allows the segment to slide smoothly against the tail seal of the shield when it separates from the shield, thereby protecting the pressure receiving plate and preventing water leakage from the tail seal.

[Brief explanation of the drawing]

The drawings show an embodiment of the earth pressure meter of the present invention, and FIGS. 1 and 2 are cross-sectional views taken along lines II and FF-II in FIG. 3, and FIG. 3 is a bottom view. 1... Segment body, 1a... Opening, 2... Skin plate, 3... Rib, 4... Frame, 5... ...Pressure plate, 6
...Rubber plate, 7...Strength gauge,
8... Lead wire, 9... Filler layer, 1
0...Sliding board.

Claims (1)

[Claims] 1. An opening is provided in the skin plate of the segment, a frame surrounding the opening and having a flange that protrudes inward from the entire inner peripheral surface is fixed to the back surface of the skin plate, and a rubber plate is sandwiched between the tunnel side of the flange and a steel A pressure receiving plate made of a flat plate is connected with bolts, a strain gauge is attached approximately to the center of the pressure receiving plate, and a filling material for transmitting earth pressure is filled into the opening on the ground side of the rubber plate until it is flush with the skin plate. An earth pressure gauge characterized in that a plurality of strip-shaped sliding plates are fixed to a segment or frame with the surface thereof matching the surface of the filler layer.