Soil body vertical deformation monitoring device and monitoring method

Abstract

The invention provides a soil body vertical deformation monitoring device and a monitoring method.The soil body vertical deformation monitoring device comprises a distributed optical fiber, a directional guide head, an axial limiting structure and a radial limiting structure, the distributed optical fiber is of a U-shaped structure and installed on the directional guide head, the axial limiting structure is used for being connected with a bottom arm of the U-shaped structure, and the radial limiting structure is used for being connected with a bottom arm of the U-shaped structure; the radial limiting structure is used for being connected with a vertical arm of the U-shaped structure to limit the distributed optical fiber to move in the axial direction of the directional guide head, and the radial limiting structure is used for being connected with the vertical arm of the U-shaped structure to limit the distributed optical fiber to move in the radial direction of the directional guide head. And a scientific basis is provided for safe construction of foundation pit engineering and environmental influence assessment.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering monitoring, and in particular to a soil vertical deformation monitoring device and a monitoring method. Background Art

[0002] In recent years, with the continuous expansion of underground space development, foundation pit projects have shown a trend of "super-large and super-deep" development. During the excavation of deep foundation pits, the soil at the bottom of the pit will rebound and rise due to the release of the ground's own weight stress, while the soil around the foundation pit may undergo settlement and deformation. If this deformation is not properly controlled, it may lead to uneven settlement of the main structure and even adversely affect adjacent buildings and underground pipelines. In severe cases, it may cause engineering accidents. Therefore, monitoring the vertical deformation of the deep soil in the foundation pit is of great significance to ensure construction safety and the stability of the surrounding environment.

[0003] Currently, vertical deformation monitoring of deep soil in foundation pits primarily relies on rebound marker technology. This involves embedding rebound markers before excavation and measuring their elevation changes to reflect soil deformation. However, this method has the following limitations: Rebound markers must be embedded before excavation, but construction disturbances can easily damage or displace measuring points, leading to data distortion. After excavation, rebound markers can be buried or damaged, making accurate positioning difficult and affecting monitoring continuity. Traditional methods rely on manual measurement, which is susceptible to environmental interference and hinders high-precision, real-time monitoring. Furthermore, deformation data can only be obtained at discrete points, failing to fully reflect the continuous deformation patterns of the soil along its depth.

[0004] To address these issues, existing technologies attempt to employ supplementary monitoring devices such as stratified settlement meters and inclinometers. However, these technologies still suffer from drawbacks such as complex installation, high cost, and poor adaptability. Therefore, there is an urgent need to develop a high-precision, highly reliable, and adaptable deep soil vertical deformation monitoring technology to meet the monitoring needs of modern deep foundation pit projects.

[0005] Distributed fiber optic sensing technology, with its strong anti-interference capabilities, high measurement accuracy, and continuous monitoring capabilities, has shown great potential in geotechnical engineering monitoring. Based on this, this paper proposes a soil vertical deformation monitoring device and method. These devices aim to accurately and real-timely monitor vertical deformation of soil at different depths within the impact zone of foundation pit construction, providing a scientific basis for safe construction and environmental impact assessment of foundation pit projects. Summary of the Invention

[0006] The purpose of the present invention is to provide a soil vertical deformation monitoring device and monitoring method to solve the problems existing in the prior art, realize continuous, accurate and real-time monitoring of the vertical deformation of soil at different depths within the influence range of foundation pit construction, facilitate construction, effectively reduce costs, and provide a scientific basis for the safe construction of foundation pit projects and environmental impact assessment.

[0007] To achieve the above object, the present invention provides the following solutions: The present invention provides a soil vertical deformation monitoring device and monitoring method, comprising: a distributed optical fiber, a directional guide head, an axial limiting structure and a radial limiting structure. The distributed optical fiber is installed on the directional guide head in a U-shaped structure. The axial limiting structure is used to connect the bottom arm of the U-shaped structure to limit the movement of the distributed optical fiber along the axial direction of the directional guide head. The radial limiting structure is used to connect the vertical arm of the U-shaped structure to limit the movement of the distributed optical fiber along the radial direction of the directional guide head.

[0008] Preferably, the axial limiting structure is a through hole opened near the bottom of the directional guide, the through hole radially passes through the directional guide, and the distributed optical fiber passes through the through hole.

[0009] Preferably, the radial limiting structure is an adhesive tape, which is used to wind the distributed optical fiber onto the directional guide and fix it.

[0010] Preferably, a protective tube is further included, and the protective tube is sleeved on the U-shaped bend of the distributed optical fiber to prevent the distributed optical fiber from breaking.

[0011] Preferably, a tapered thread is provided on the top of the directional guide.

[0012] Preferably, a cross wedge structure is provided at the bottom of the directional guide.

[0013] Preferably, it further comprises a steel pipe, which is buried under the ground and arranged perpendicular to the ground, and the distributed optical fiber passes through the steel pipe.

[0014] Preferably, it also includes a protective cover, which is in the shape of a cylinder with a concave bottom. Two through holes are opened on the protective cover along the axial direction of the directional guide head for passing two distributed optical fibers. The protective cover is located above the steel pipe.

[0015] A monitoring method for a soil vertical deformation monitoring device comprises the following steps: Step S1: drilling a hole in the ground; Step S2: connecting the distributed optical fiber to the directional guide; Step S3: driving the directional guide and the distributed optical fiber connected to the directional guide into the bottom of the hole and fully inserting them into the formation, and straightening the distributed optical fiber during the process of driving the distributed optical fiber into the bottom of the hole; Step S4: Collecting vertical deformation data of deep soil.

[0016] Preferably, the method further comprises the following steps: Step S3.1: Filling the drill hole with clay balls, and backfilling the holes in layers; Step S3.2: After the clay balls are backfilled, a protective structure is buried to protect the distributed optical fiber.

[0017] Compared with the prior art, the present invention has achieved the following technical effects: The present invention utilizes an axial limiting structure and a radial limiting structure to connect the distributed optical fiber to the directional guide head, so that the distributed optical fiber can be buried in the deep soil together with the directional guide head. No heavy equipment is required, the construction is convenient, and the cost is effectively reduced. It is suitable for narrow sites such as foundation pits, tunnels, etc., and is more adaptable to complex soil layers. Whether it is soft soil, sand layer or rock layer, the directional guide head can be used to stably bury the distributed optical fiber under the soil layer; and the characteristics of the distributed optical fiber can be used to monitor the deformation of the deep soil. The distributed optical fiber is used as a sensor to obtain the strain / temperature distribution along the entire distributed optical fiber in real time, and comprehensively reflect the continuous deformation law of the soil along the depth, solving the problem that traditional point sensors can only measure discrete points; and the distributed optical fiber adopts optical signal transmission, is not easily affected by environmental factors, and can be monitored in real time with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of an embodiment of the present invention.

[0020] Figure 2 Schematic diagram of a directional guide in an embodiment of the present invention.

[0021] Figure 3 Schematic diagram of distributed optical fiber fixation in an embodiment of the present invention.

[0022] Among them, 1. directional guide; 2. distributed optical fiber; 3. protective tube; 4. through hole; 5. steel pipe; 6. protective cover; 7. clay ball; 8. axial limiting structure; 9. radial limiting structure; 10. tapered thread; 11. cross wedge structure. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] The purpose of the present invention is to provide a soil vertical deformation monitoring device and monitoring method to solve the problems existing in the prior art, realize continuous, accurate and real-time monitoring of the vertical deformation of soil at different depths within the influence range of foundation pit construction, facilitate construction, effectively reduce costs, and provide a scientific basis for the safe construction of foundation pit projects and environmental impact assessment.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figures 1 to 3 As shown, the present invention provides a soil vertical deformation monitoring device, including: a distributed optical fiber 2, a directional guide head 1, an axial limiting structure 8 and a radial limiting structure 9. The distributed optical fiber 2 is installed on the directional guide head 1 in a U-shaped structure. The U-shaped structure consists of a bottom arm and two vertical arms. The bottom arm is a curved section connecting the vertical arms on both sides, and the vertical arms are vertical sections extending from both ends of the bottom arm. The axial limiting structure 8 is used to connect the bottom arm of the U-shaped structure to limit the movement of the distributed optical fiber 2 along the axial direction of the directional guide head 1. The radial limiting structure 9 is used to connect the vertical arms of the U-shaped structure to limit the movement of the distributed optical fiber 2 along the radial direction of the directional guide head 1.

[0027] Furthermore, the directional guide 1 is made of stainless steel, has a length of 30 cm to 50 cm, and a diameter of 8 cm to 12 cm.

[0028] As a preferred embodiment, the axial limiting structure 8 is a through hole 4 provided near the bottom of the directional guide 1 . The through hole 4 radially penetrates the directional guide 1 , and the distributed optical fiber 2 passes through the through hole 4 .

[0029] Furthermore, the diameter of the through hole 4 is 2 cm to 4 cm.

[0030] Furthermore, the axial limiting structure 8 is an ear plate arranged near the bottom of the directional guide 1, and a hole is reserved on the ear plate for the distributed optical fiber 2 to pass through.

[0031] Furthermore, the axial limiting structure 8 is a U-shaped groove axially opened on the surface of the directional guide 1 , and the distributed optical fiber 2 is embedded in the U-shaped groove. The U-shaped groove limits the distributed optical fiber 2 along the axial direction of the directional guide 1 .

[0032] As a preferred embodiment, the radial limiting structure 9 is an adhesive tape, which is used to wind the distributed optical fiber 2 around and fix it on the directional guide 1 .

[0033] Furthermore, the radial limiting structure 9 is a spring pressing piece, which is fixed on the directional guide 1 to press and fix the distributed optical fiber 2 on the directional guide 1 .

[0034] As a preferred embodiment, a protection tube 3 is further included. The protection tube 3 is sleeved on the U-shaped bend of the distributed optical fiber 2 to prevent the distributed optical fiber 2 from breaking.

[0035] Furthermore, the protection tube 3 is a PVC protection tube, the PVC protection tube passes through the through hole 4 , and both ends of the PVC protection tube are exposed outside the through hole 4 .

[0036] As a preferred embodiment, a tapered thread 10 is provided on the top of the directional guide 1 .

[0037] Furthermore, the tapered thread 10 on the top of the directional guide head 1 is used to connect to the drill rod of the drilling rig, and the size of the tapered thread 10 is adjusted according to the size of the drill rod.

[0038] Furthermore, the tapered thread 10 at the top of the directional guide head 1 has a bottom diameter of 3 cm and a top diameter of 6 cm, and is used to match a 50 drill rod.

[0039] Furthermore, the tapered thread 10 on the top of the directional guide head 1 and the drill rod only need to be connected by 1 to 2 threads.

[0040] As a preferred embodiment, a cross wedge structure 11 is provided at the bottom of the directional guide head 1. The functions of the cross wedge structure 11 are, firstly, to prevent the directional guide head 1 from reversing along with the drill rod of the drill rig when the drill rod is reversed so that it loosens from the tapered thread 10 on the top of the directional guide head 1; and secondly, to prevent the distributed optical fiber 2 from rotating during use after the directional guide head 1 is inserted into the ground.

[0041] Furthermore, the cross-wedge structure 11 includes two cross-intersecting units with a crossing angle of 90 degrees, and the cross section of each unit is triangular.

[0042] As a preferred embodiment, it further includes a steel pipe 5 , which is buried under the ground and arranged perpendicular to the ground, and the distributed optical fiber 2 passes through the steel pipe 5 .

[0043] Furthermore, the diameter of the steel pipe 5 is 10 cm and the length is 1 meter.

[0044] As a preferred embodiment, it also includes a protective cover 6, which is a cylindrical shape with a concave bottom. Two through holes 4 are opened on the protective cover 6 along the axial direction of the directional guide head 1 for passing two distributed optical fibers 2. The protective cover 6 is located above the steel pipe 5.

[0045] A monitoring method for a soil vertical deformation monitoring device comprises the following steps: Step S1: Drill holes are opened in the stratum; specifically, before excavation of the foundation pit, layout points are selected according to the stratum conditions, design documents and monitoring drawings, and a drill rig is used to drill holes with a diameter of 13 cm to 17 cm.

[0046] Step S2: Connect the distributed optical fiber 2 to the directional guide 1; specifically, insert the distributed optical fiber 2 into the through hole 4 on the directional guide 1, and use a PVC tube to protect the distributed optical fiber 2 at the position of the through hole 4 of the directional guide 1 to prevent the distributed optical fiber 2 from being damaged during the burial process. Then, wrap the distributed optical fiber 2 and the directional guide 1 with tape to fix them so that the optical fiber is installed on the directional guide 1 in a U-shaped structure.

[0047] Step S3: Drive the directional guide 1 and the distributed optical fiber 2 connected to the directional guide 1 into the bottom of the hole and fully insert them into the formation, and straighten the distributed optical fiber 2 during the process of driving the distributed optical fiber 2 into the bottom of the hole; specifically, connect the directional guide 1 to the drill rod of the drilling rig, and only need to connect 1~2 threads, and drive the directional guide 1 with the distributed optical fiber 2 into the bottom of the hole through the drill rod. During the burial process, straighten the two optical fibers manually or by other means, and cooperate with the drill rod to drive the directional guide 1 with the distributed optical fiber 2 into the bottom of the hole.

[0048] Step S4: Collecting the vertical deformation data of the deep soil. Specifically, after all the construction is completed, the initial vertical deformation data of the deep soil can be collected after standing for 2 to 3 days.

[0049] As a preferred embodiment, a monitoring method of a soil vertical deformation monitoring device further includes the following steps: Step S3.1: Fill the drill hole with clay balls 7, and backfill the clay balls 7 in layers; specifically, after the drill rod is removed, fill the drill hole with clay balls 7, and backfill the clay balls 7 in layers to prevent blockage due to instantaneous burial of too many clay balls.

[0050] Step S3.2: After the clay balls 7 are backfilled, a protective structure is buried to protect the distributed optical fiber 2. Specifically, after the clay balls 7 are backfilled, the distributed optical fiber 2 is inserted into a 10 cm diameter, 1 m long steel pipe 5 and placed at the borehole. A PVC protective cover 6 is buried under the ground at the borehole to protect the distributed optical fiber 2.

[0051] The present invention utilizes an axial limiting structure 8 and a radial limiting structure 9 to connect the distributed optical fiber 2 to the directional guide 1, so that the distributed optical fiber 2 can be buried in the deep soil together with the directional guide 1. No heavy equipment is required, the construction is convenient, and the cost is effectively reduced. It is suitable for narrow sites such as foundation pits, tunnels, etc., and is more adaptable to complex soil layers. Whether it is soft soil, sand layer or rock layer, the directional guide 1 can be used to stably bury the distributed optical fiber 2 under the soil layer; and the characteristics of the distributed optical fiber 2 can be used to monitor the deformation of the deep soil. The distributed optical fiber 2 is used as a sensor to obtain the strain / temperature distribution along the entire distributed optical fiber 2 in real time, and comprehensively reflect the continuous deformation law of the soil along the depth, solving the problem that traditional point sensors can only measure discrete points; and the distributed optical fiber 2 adopts optical signal transmission, is not easily affected by environmental factors, and can be monitored in real time with high accuracy.

[0052] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A soil vertical deformation monitoring device, characterized in that: include: A distributed optical fiber (2), a directional guide (1), an axial limiting structure (8), and a radial limiting structure (9), wherein the distributed optical fiber (2) is mounted on the directional guide (1) in a U-shaped structure, the axial limiting structure (8) is used to connect the bottom arm of the U-shaped structure to limit the movement of the distributed optical fiber (2) along the axial direction of the directional guide (1), and the radial limiting structure (9) is used to connect the vertical arm of the U-shaped structure to limit the movement of the distributed optical fiber (2) along the radial direction of the directional guide (1).

2. The soil vertical deformation monitoring device according to claim 1, characterized in that: The axial limiting structure (8) is a through hole (4) provided near the bottom of the directional guide (1), the through hole (4) radially passes through the directional guide (1), and the distributed optical fiber (2) passes through the through hole (4).

3. The soil vertical deformation monitoring device according to claim 1, characterized in that: The radial limiting structure (9) is an adhesive tape, used for winding and fixing the distributed optical fiber (2) on the directional guide (1).

4. The soil vertical deformation monitoring device according to claim 1, characterized in that: It also includes a protection tube (3), which is sleeved on the U-shaped bend of the distributed optical fiber (2) to prevent the distributed optical fiber (2) from breaking.

5. The soil vertical deformation monitoring device according to claim 1, characterized in that: A tapered thread (10) is provided on the top of the directional guide (1).

6. The soil vertical deformation monitoring device according to claim 1, characterized in that: A cross wedge-shaped structure (11) is provided at the bottom of the directional guide (1).

7. The soil vertical deformation monitoring device according to claim 1, characterized in that: It also includes a steel pipe (5), which is buried under the ground and arranged perpendicular to the ground, and the distributed optical fiber (2) passes through the steel pipe (5).

8. The soil vertical deformation monitoring device according to claim 7, characterized in that: It also includes a protective cover (6), which is in the shape of a cylinder with a concave bottom. Two through holes are provided on the protective cover (6) along the axial direction of the directional guide (1) for passing the two distributed optical fibers (2). The protective cover (6) is located above the steel pipe (5).

9. A monitoring method for a soil vertical deformation monitoring device, characterized in that: The application of the soil vertical deformation monitoring device according to any one of claims 1 to 8 comprises the following steps: Step S1: drilling a hole in the ground; Step S2: connecting the distributed optical fiber (2) to the directional guide (1); Step S3: driving the directional guide (1) and the distributed optical fiber (2) connected to the directional guide (1) into the bottom of the hole and fully inserting them into the formation, and straightening the distributed optical fiber (2) during the process of driving the distributed optical fiber (2) into the bottom of the hole; Step S4: Collecting vertical deformation data of deep soil.

10. The monitoring method of the soil vertical deformation monitoring device according to claim 9, characterized in that: The following steps are also included: Step S3.1: Filling the drill hole with clay balls (7), wherein the clay balls (7) are backfilled in layers; Step S3.2: After the backfilling of the clay balls (7) is completed, a protective structure is buried to protect the distributed optical fiber (2).

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