JP-2026076360-A - Condition measuring device and method for burying the condition measuring device

Abstract

[Problem] To perform measurements simultaneously on buried optical fiber cables. [Solution] The condition measuring device 100 comprises an optical fiber cable 50 that is folded and embedded in a borehole 2 formed vertically downward in the ground 1, a cover member 60 that covers the folded portion 50a of the optical fiber cable 50, a weight 262 attached to the cover member 60, and a measuring device 70 installed outside the borehole 2 to which one end of the optical fiber cable 50 is connected. The measuring device 70 has a light source of pulsed light that is incident on the optical fiber cable 50. [Selection Diagram] Figure 6

Inventors

• 黒川 紗季
• 岡本 圭司
• 野中 隼人

Assignees

• 鹿島建設株式会社

Dates

Publication Date

20260511

Application Date

20260219

Claims (7)

1. A condition measuring device that measures the condition of an object to be measured using an optical fiber cable, The optical fiber cable is folded and buried in a hole formed vertically downward in the ground, A cover member that covers the folded portion of the optical fiber cable, The weight attached to the cover member, The device comprises a measuring device installed outside the hole and to which one end of the optical fiber cable is connected, The measuring device has a light source of pulsed light that is incident on the optical fiber cable. Condition measuring device.
2. The system further comprises a rope with one end connected to the cover member or the weight, The rope is capable of suspending and supporting the cover member and the weight when the cover member is inserted into the hole together with the weight. The condition measuring device according to claim 1.
3. The optical fiber cable is folded back and embedded in the grout filled in the hole. The condition measuring device according to claim 1.
4. The cover member has a housing portion formed in a shape capable of accommodating the folded portion of the optical fiber cable. A condition measuring device according to any one of claims 1 to 3.
5. A method for burying a condition measuring device, which measures the condition of an object to be measured using an optical fiber cable, in a hole formed vertically downward in the ground, The aforementioned condition measuring device is The optical fiber cable is buried in the hole, folded back so as to reciprocate along the axial direction, A cover member that covers the folded portion of the optical fiber cable, The cover member is equipped with a weight attached to it, The cover member is inserted into the hole together with the weight, or the weight is inserted into the hole before the cover member. Method for burying a condition measurement device.
6. With the tip of the cover member in contact with the bottom of the hole, grout is filled into the hole. The method for burying a condition measuring device according to claim 5.
7. The condition measuring device further comprises a rope with one end connected to the cover member or the weight, When inserting the cover member together with the weight into the hole, the rope is used to suspend and support the cover member and the weight. A method for burying a condition measuring device according to claim 5 or claim 6.

Description

This invention relates to a condition measuring device and a method for burying a condition measuring device. Patent Document 1 discloses a condition measuring device that measures the condition of the ground using optical fiber cables buried in the ground. Japanese Patent Publication No. 2002-156215 This figure shows a state measuring device according to an embodiment of the present invention.This is a cross-sectional view illustrating the configuration of the first optical fiber cable.This is a cross-sectional view illustrating the configuration of the second optical fiber cable.This figure shows a cover member of a condition measuring device according to an embodiment of the present invention.This figure shows a modified example of the cover member of a condition measuring device according to an embodiment of the present invention.This figure shows a modified example of a state measuring device according to an embodiment of the present invention. The following description of a state measuring device according to an embodiment of the present invention will be given with reference to the drawings. First, the configuration of the state measuring device 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 4. The state measuring device 100 is a device that measures the state of the ground 1, which is the object to be measured, using an optical fiber cable 50 embedded in the ground 1. Note that the object to be measured is not limited to the ground 1; it can be anything that allows for the embedding of the optical fiber cable 50, such as a concrete structure like a dam. Note that the embodiment shown in Figure 1 is a reference example not included in the technical scope of the invention claimed in this application, and is an embodiment disclosed in the application before division. In the construction of civil engineering structures, understanding the ground conditions, such as landslides, is crucial. Furthermore, understanding the progression of loosening zones in the ground during the excavation of underground cavities such as tunnels is essential for stable excavation. Therefore, to detect underground strain and loosening zones, for example, as shown in Figure 1, an optical fiber cable 50 is embedded in a borehole 2 (insertion hole) excavated vertically upward in the ground 1. The borehole 2 is a closed hole, with one end closed inside the ground or structure being measured, and the other end open to the ground or structure being measured. The optical fiber cable 50 embedded in the borehole 2 undergoes deformation in response to underground strain and loosening of the ground 1. Therefore, as described later, by measuring the deformation of the optical fiber cable 50, it is possible to measure the underground strain and loosening of the ground 1. The condition measuring device 100 shown in Figure 1 mainly comprises: an optical fiber cable 50 embedded in the borehole 2, folded back so as to reciprocate along the axial direction; a pipe material 10 to which the optical fiber cable 50 is attached; a cover member 60 attached to the tip of the pipe material 10 to cover the folded portion 50a of the optical fiber cable 50; an expanding body 20 attached to the cover member 60 that can expand radially outward from the borehole 2; and a filling hose 30 provided along the pipe material 10. The pipe material 10 is a hollow, elongated member formed from a resin such as polyvinyl chloride, with an outer diameter sufficiently smaller than the inner diameter of the borehole 2. It has an internal passage 11 formed axially through the pipe, and a communication hole 12 at one end of the inner circumferential surface of the internal passage 11, connecting the inside and outside of the pipe material 10. The communication hole 12 is formed on the tip side of the pipe material 10 when the condition measuring device 100 is inserted into the borehole 2. It functions as an outlet for discharging air from the borehole 2 to the outside when grout 40 (filling material) is being filled into the borehole 2 through the filling hose 30. The diameter-expanding body 20 includes an expansion portion 22 that expands radially outward in response to the pressure of the supplied fluid, a support portion 21 that supports the expansion portion 22 radially inward, and a supply pipe 24 that supplies the pressurized fluid. Figure 1 shows the expansion portion 22 expanding radially outward from the borehole 2, and the expansion portion 22 pressing against the inner wall surface of the borehole 2. The expansion section 22 is a rubber or metal member with an outer shape formed in the form of a barrel or cylinder, and is supported by the support section 21 so as to expand radially outward in response to the pressure of the fluid supplied to the space (not shown) formed between the support section 21 and the expansion section 22. The support portion 21 is fixed to the outer surface of the cover member 60 v