CN108007789B - Physical model test device for influencing adjacent buried pipelines by instability of deep foundation pit - Google Patents

Abstract

A physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines. The device frame includes a rectangular opening, a spring support slideway and an arc-shaped trench. The rectangular opening is located on the left and right sides of the device body, with two holes on each side. At least two rectangular openings are provided up and down; the pipe sliding platform includes a chute, a pipe bracket and a sleeve. The chute is located at the upper and lower ends of the rectangular opening. The pipe bracket is slidably located in the chute, and the sleeve is embedded in the ring set by the pipe bracket. , the two ends of the buried pipeline are located in the left and right sleeves respectively; the spring support slideway is located in the middle of the front end of the device frame, and the arc-shaped groove is located in the middle of the bottom end of the device frame; the support structure includes spring supports, springs and retaining soil plate. The invention can simulate the instability situation in deep foundation pits, the impact on buried pipelines of different positions and different diameters nearby, measure and analyze the strain characteristics and damage process of buried pipelines during the test, and provide solutions for buried pipelines. Provide experimental basis for the cause of damage.

Description

Physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines

Technical field

The invention relates to a simulation test device in the pipeline transportation industry, specifically a physical model test device that simulates the impact of deep foundation pit instability on adjacent buried pipelines.

Background technique

The physical model test of pipe-soil interaction belongs to the category of geotechnical engineering model test. Its theory originated from the structural model test established in the early 20th century. It has gradually developed and extended to pipe-soil interaction field model test and pipe-soil interaction framework. There are many research directions such as model tests, centrifugal model tests of pipe-soil interaction and comprehensive model tests of pipe-soil interaction. Among them, the pipe-soil interaction frame model test refers to making a model using similar materials that meet the similarity criterion in the frame model slot in a normal gravity field, and measuring its deformation and various parameters when the model meets the main boundary conditions. Mechanical property parameters. This test can not only visually observe the movement characteristics of the sliding body during the sliding process, but also quantitatively obtain the stress, strain, displacement and other parameters of the pipeline and soil, and can clarify the mechanism of pipe-soil interaction from a qualitative and quantitative perspective. .

In the case of pipe-soil interaction frame model test, pipe-soil interaction generally occurs under external force conditions. The main methods of external force include: seismic waves simulated by mechanical vibration or blasting; rainfall simulators simulate seepage under rainfall conditions; artificial loading provides soil gravity at the top of the force model.

Based on the above technical background, the process of simulating the impact of deep foundation pit instability on adjacent buried pipelines in this invention mainly has the following limitations and defects:

(1) The current position control system cannot achieve a clear control effect, and has a complex structure, high cost, and cumbersome operation, making it difficult to meet the requirements for fast and accurate pipeline position control;

(2) The internal stress and strain of the soil are complex, and the instability of the foundation pit caused by various factors is difficult to simulate;

(3) There are size effects and boundary effects in simulating the instability process of deep foundation pits.

Contents of the invention

In order to overcome the shortcoming of the existing technology that cannot simulate the impact of deep foundation pit instability on adjacent buried pipelines, the present invention provides a physical model test device that can simulate the impact of deep foundation pit instability on adjacent buried pipelines. This device can be used to simulate the instability of deep foundation pits and its impact on nearby buried pipelines of different locations and diameters, and measure and analyze the strain characteristics and damage processes of buried pipelines during the test. Provide experimental basis for the causes of damage to buried pipelines.

The technical solutions adopted by the present invention to solve the technical problems are:

A physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines, including a device frame and a supporting structure. The device frame includes a rectangular opening for installing a pipeline sliding platform, a spring support slide and a support structure. In the arc-shaped trench for installing the retaining plate, the rectangular openings are located on the left and right sides of the device body, and at least two rectangular openings are provided up and down on each side; the pipeline sliding platform includes a chute, a pipeline bracket and a sleeve, so The chute is located at the upper and lower ends of the rectangular opening, the pipe bracket is slidably located in the chute, the sleeve is embedded in the ring provided by the pipe bracket, and the two ends of the buried pipe are respectively located in the left and right sleeves; The spring support slideway is located in the middle of the front end of the device frame, and the arc-shaped groove is located in the middle of the bottom end of the device frame; the support structure includes a spring support, a spring and a retaining plate, and the spring support is installed into a spring The support slide can slide along the spring support slide. One end of the spring is installed on the spring support, and the other end of the spring touches the retaining plate. The bottom end of the retaining plate is in contact with the retaining plate. The arc-shaped grooves fit together, and the retaining plate is erected in the middle of the device frame.

Further, the supporting structure also includes a sliding piece, which is located on the spring support and can slide up and down along the spring chute, and the spring is installed on the sliding piece.

Furthermore, the pipe support is placed in the pipe sliding platform, and the lower end of the pipe support is tangent to the bearing.

Furthermore, the test device also includes a position control system. The position control system includes a lock. The upper end of the pipeline support is provided with equidistant round holes as size holes for controlling the position. The lock can be inserted into the upper end of the pipeline sliding platform. The round hole left in the middle of the groove is connected with the size hole, which plays the role of fixing the pipe bracket and controlling the position of the pipe.

The test device also includes a moving device, which is assembled from a wheel platform and a pulley. The four wheel platforms are respectively located at the four corner ends of the bottom end of the device frame, and the pulleys are installed in the wheel platform.

In the pipeline sliding platform, the distance between the upper and lower chute is close to the height of the pipeline bracket.

The push rod is located at the rear end of the device frame.

The beneficial effects of the present invention are mainly manifested in:

(1) This test device can be applied to the pipe-soil interaction frame model test to simulate the instability of deep foundation pits and cause pipe-soil interaction through different disassembly methods of retaining plates;

(2) The test device has a simple structure and is easy to operate. A lightweight plate can be placed on the top of the physical model of the deep foundation pit, and an appropriate amount of weights can be stacked on the lightweight plate to meet the load requirements of the test;

(3) The position control system of the test device is simple in structure and can accurately control the position of the buried pipeline to a certain extent;

(4) This test device can not only simulate the impact of deep foundation pit instability on adjacent buried pipelines, but also simulate the impact of deep foundation pit excavation on adjacent buried pipelines, and can also study the instability of deep foundation pits. Below, the influence of factors such as pipe diameter and pipe location on the test results;

(5) The components of the test device have high strength and rigidity, and the possibility of damage to the components is very low. Even if they are damaged, they can be easily repaired or replaced;

(6) The support structure of this test device can highly simulate the support structure of a deep foundation pit. By replacing different springs to change the support strength and the height of the spring, different foundation pit support methods can be simulated.

(7) The retaining plate of the test device is fixed by four nuts. Removing the lower end nuts can simulate the process of the lower end of the supporting structure being destroyed first. By removing the upper nut, you can simulate the process of the upper end of the supporting structure being destroyed first. Completely dismantling the retaining plate can simulate the complete instability process of a deep foundation pit.

(8) This test device can be used as a reference object for geotechnical engineering model tests, with low cost, broad application prospects, and significant economic benefits.

Description of the drawings

Figure 1 is a schematic three-dimensional structural diagram of an embodiment of the present invention.

Figure 2 is the left view of Figure 1

Figure 3 is a top view of Figure 1

Figure 4 is a bottom view of Figure 1

Figure 5 is the device frame structure diagram

Figure 6 shows the structure diagram of the pipeline bearing platform

Figure 7 is the structural diagram of the spring support.

Figure 8 shows the structure diagram of the pipe support

In the picture: 1—device frame, 2—hand push rod, 3, 8—nut, 4—sleeve, 5—lock, 6—buried pipe, 7—pipe bracket, 9—spring, 10—spring support. , 11—screw, 12, 16, 19, 20, 21, 25—screw hole, 13—bearing, 14—wheel platform, 15—pulley, 17—upper chute, 18—lower chute, 22—arc groove Groove, 23—sliding plate, 24—spring chute, 26—retaining plate, 27—size hole.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

Referring to Figures 1 to 8, a physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines includes a device frame, a position control system, a supporting structure and a mobile device.

In order to make full use of the space of the test device, the device frame 1 is designed with a three-layer pipeline sliding platform. The three-layer pipeline sliding platform is 300mm apart and 400mm wide. This ensures that the buried pipeline 6 has sufficient moving space in the test device and can maximize the realization of Different locations of buried pipelines 6.

The pipe bracket 7 is installed in the pipe sliding platform, and its degree of freedom is limited by the upper chute 17 and the lower chute 18. Through the sliding action of the bearing 13, it can slide horizontally left and right along the chute 17, 18. There is a ring with a diameter of 140mm in the middle of the pipe branch 7, and the sleeve 4 can be embedded in the ring. The sleeve 4 has multiple models, the outer diameter of each model is 140mm, and the inner diameter is close to the outer diameter of the buried pipe 6. It is convenient to insert the buried pipeline 6. After the above operations are completed, the buried pipeline can slide in the pipeline sliding platform. The upper part of the pipe support 7 is provided with 15 round holes with a spacing of 20mm, which can be used as size holes 27. There is a round hole in the middle of the upper chute 17. The latch 5 can pass through the round holes and be inserted into the size hole 27 to achieve fixed burial. Pipes, and more accurately determine the location of buried pipelines, avoiding the disadvantages of naked eye positioning, reducing errors, and making the experimental results more convincing.

The present invention is mainly aimed at simulating the instability of one-sided deep foundation pits. The instability forms of one-sided deep foundation pits mainly include: arc sliding, top toppling, bottom moving outward, and wall translation. In order to more realistically simulate the changes in support strength during the instability process of the foundation pit, the present invention introduces the elastic force of the spring. For the different forms of instability of the deep foundation pit, the specific operations are as follows:

(1) Arc sliding: Place a lightweight plate at the rear edge of the top of the deep foundation pit physical model, and stack an appropriate amount of weight on the lightweight plate. Insert the screws 11 into the screw holes 25 and 12 to fix the spring support 10 in the appropriate position. Use a spring 9 with a suitable elastic coefficient to be installed on the sliding plate 23. Move the sliding plate 23, adjust the spring 9 to a lower position, and resist the lower edge of the retaining plate 26. Remove the nuts at the screw holes 19 and 21, and then remove the nuts from the screw holes 19 and 21. The upper end of the soil plate 26 is fixed by the nut, and the lower end is unstable. Under the pressure of the trailing edge weight, arc sliding will occur.

(2) Top tipping: Use screw 11 to insert screw holes 25 and 12, and fix spring support 10 at the appropriate position. A spring 9 with a suitable elastic coefficient is installed on the sliding piece 23, and the sliding piece 23 is moved to adjust the spring 9 to the middle position of the spring support 10 and against the middle part of the retaining plate 26. Remove the nuts at screw holes 16 and 20. The lower end of the retaining plate 26 will be fixed by the nuts, and the upper end will become unstable and the top will tip over.

(3) Move the bottom outward: Use screws 11 to insert into the screw holes 25 and 12 to fix the spring support 10 at the appropriate position. A spring 9 with a suitable elastic coefficient is installed on the sliding piece 23, and the sliding piece 23 is moved to adjust the spring 9 to the upper end position of the spring support 10 and against the middle part of the retaining plate 26. Remove the nuts at screw holes 19 and 21. The upper end of the retaining plate 26 will be fixed by the nuts, and the lower end will become unstable, causing the bottom to move outward.

(4) Wall translation: Use screws 11 to insert into the screw holes 25 and 12, and fix the spring support 10 at the appropriate position. A spring 9 with a suitable elastic coefficient is installed on the sliding piece 23, and the sliding piece 23 is moved to adjust the spring 9 to the middle position of the spring support 10 and against the middle part of the retaining plate 26. Remove the nuts at screw holes 16, 19, 20, and 21. Except for the spring force and the lateral pressure generated by the soil, the retaining plate 26 is not subject to any constraints, and the wall will move.

The test process of the present invention to simulate the impact on adjacent pipelines under the condition of deep foundation pit instability (top toppling) is roughly as follows:

Part One, Preliminary Preparation

1. Based on the research needs and based on the principle of similarity, a generalized pipe-soil similarity model is formulated; using similar material test results as the standard, similar soil materials are prepared;

2. Purchase materials such as pipes, strain gauge sensors, and strain gauges.

Part 2: Adjustment and fixation of the device

3. The pipe bracket 7 is installed in the pipe sliding platform, and the sleeve 4 is embedded in the ring where the pipe bracket 7 is left;

4. Install the buried pipe 6 with the strain gauge implanted into the sleeve 4 of the corresponding model. After determining the position of the buried pipe 6, insert the lock 5 into the round hole and the size hole 13 left in the upper chute and fix it. Buried pipeline 6;

5. For pipeline sliding platforms that do not have buried pipelines installed, temporarily install retaining plates with the same length, width and thickness as the pipeline supports;

6. Press the wheel brake in wheel platform 14 to fix the test device.

7. Use nuts to fix the retaining plate 26 through the screw holes 16, 19, 20, and 21.

8. Install the spring support 10 into the spring support slideway. The sliding piece 23 is installed on the spring support 10. The spring 9 is installed on the sliding piece 23. Adjust the position of the spring 9 so that the spring 9 contacts the retaining plate 26. the middle position.

9. Use nuts to fix the spring support 10 at the appropriate position in the spring support slideway.

10. Apply lubricating oil to the closed space between the sliding platform of the installation pipeline and the retaining plate 26 to reduce the boundary effect, and fill the prepared soil layered (thickness 50mm) into it. For each layer filled, use the standard Use a tamping plate to lightly compact the soil until the thickness of the soil meets the test requirements, and try not to disturb the buried pipeline 6 during the filling of the soil.

Part 3. Test Monitoring

11. The strain gauge implanted inside the buried pipeline 6 is connected to the strain gauge sensor and mainly collects pipeline deformation data.

12. Remove the nuts at the screw holes 16 and 20, so that the upper end of the retaining plate 26 loses its restraint.

13. The soil generates lateral pressure and deforms, causing pipe-soil interaction.

14. Record the 6 positions of the buried pipeline, collect the strain gauge sensor data, and keep it for analysis.

4. End of test

15. Remove the spring support 10, spring 9, slide 23, and retaining plate 26 in order to facilitate soil cleaning.

16. Remove the buried pipe 6, pipe bracket 7, and sleeve 4 in sequence.

17. Clean the parts of the test device, wipe them dry with a dry rag, and keep them clean.

18. Push the test device to a suitable environment for storage. If possible, apply oil to prevent rust.

The core of the present invention lies in the position control system and supporting structure of the buried pipeline, which can realize that the buried pipeline 6 is placed at different positions inside the foundation pit soil, which facilitates the study of the buried pipeline 6 in the case of instability of the deep foundation pit. The impact of its location. In addition, the influence of the diameter of the buried pipeline 6 on the instability of the deep foundation pit can also be studied to achieve multi-functionality. Combined with the instability forms of deep foundation pits on site, the present invention uses a simple structure composed of retaining plates, spring supports, and springs, which can basically simulate the four forms of instability of deep foundation pits on one side. It is efficient, low-cost, and easy to use. It has a wide range and can be used to simulate a variety of foundation pit instability situations.

Claims (6)

1. A physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines, characterized by: including a device frame and a supporting structure. The device frame includes a rectangular opening for installing a pipeline sliding platform, a spring The support slideway and the arc-shaped trench for installing the retaining plate, the rectangular openings are located on the left and right sides of the device body, and at least two rectangular openings are provided up and down on each side; the pipeline sliding platform includes a chute, a pipeline Bracket and sleeve, the chute is located at the upper and lower ends of the rectangular opening, the pipe bracket is slidably located in the chute, the sleeve is embedded in the ring set by the pipe bracket, and the two ends of the buried pipe are located on the left and right respectively. Inside the sleeve; the spring support slideway is located in the middle of the front end of the device frame, and the arc-shaped groove is located in the middle of the bottom end of the device frame; the support structure includes a spring support, a spring and a retaining plate, and the The spring support is installed into the spring support slideway and can slide along the spring support slideway. One end of the spring is installed on the spring support, and the other end of the spring touches the retaining plate. The bottom end of the retaining plate fits into the arc-shaped groove, and the retaining plate is erected in the middle of the device frame; The test device also includes a position control system. The position control system includes a lock. The upper end of the pipeline support is provided with equidistant round holes as size holes for controlling the position. The lock can be inserted into the middle of the chute at the upper end of the pipeline sliding platform. In the round holes, the connecting size holes play the role of fixing the pipe bracket and controlling the position of the pipe. 2. The physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines according to claim 1, characterized in that: the support structure further includes a sliding plate, and the sliding plate is located on a spring support , can slide up and down along the spring slide, and the spring is installed on the slide. 3. The physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines according to claim 1 or 2, characterized in that: the pipeline bracket is placed in the pipeline sliding platform, and the lower end of the pipeline bracket is in contact with the bearing. cut. 4. The physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines according to claim 1 or 2, characterized in that: the test device further includes a moving device, and the moving device is composed of a wheel platform and a The pulleys are assembled, and the four wheel platforms are respectively located at the four corner ends of the bottom end of the device frame, and the pulleys are installed in the wheel platforms. 5. The physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines according to claim 1 or 2, characterized in that: in the pipeline sliding platform, the upper and lower end chutes are separated by a distance close to the pipeline support the height of. 6. The physical model test device for the impact of deep foundation pit instability on adjacent buried pipelines according to claim 1 or 2, characterized in that: the hand push rod is located at the rear end of the device frame.