Centrifugal machine test device for simulating foundation pit excavation by using paraffin and laser

Abstract

The utility model discloses a centrifuge test device for simulating foundation pit excavation by using paraffin and laser, which comprises a model box and an equipment box, the upper part of the model box is open, a test soil sample is arranged in the model box, an underground diaphragm wall model is pre-buried in the test soil sample, and the equipment box is arranged in the equipment box. The underground diaphragm wall model extends along the width of the whole inner opening of the model box, the bottom of the underground diaphragm wall model is suspended on a bottom plate of the model box, a foundation pit model is formed between the underground diaphragm wall model and the left side wall of the model box, and the foundation pit model is filled with solid paraffin; the diaphragm wall model is provided with a horizontal supporting rod, the horizontal supporting rod is of an electric telescopic structure, and a via hole corresponding to the horizontal supporting rod is formed in the left side wall of the model box. A laser instrument is arranged above the foundation pit model and installed on a support, the front side wall of the model box is transparent, and a camera is arranged in front of the front side wall of the model box. The device can accurately simulate layered excavation of the foundation pit, and is small in disturbance in the test process, convenient to operate, low in cost and high in safety.

Description

Technical Field

[0001] The utility model relates to a centrifuge test device, in particular to a centrifuge test device which utilizes paraffin and laser to simulate foundation pit excavation. Background Art

[0002] With the advancement of urbanization, underground space is regarded as an important resource for urban development. The development of urban underground space is gradually extending in a deeper and larger direction. The construction of large-scale urban transportation hubs, large-scale commercial complexes, large-scale CBDs, etc. has greatly increased the area of ​​foundation pits and the depth of excavation. At present, the foundation pit projects in many cities are experiencing leapfrog development in scale, depth and difficulty. At the same time, with the vigorous development of the domestic infrastructure industry and the significant improvement in the utilization rate of urban underground space in the past two decades, foundation pit excavation adjacent to existing buildings has become more and more frequent. How to improve the safety of foundation pit construction and reduce its impact on surrounding buildings has received more and more attention. In summary, the field of foundation pit engineering is gradually becoming the focus and key issue of underground engineering research.

[0003] Field test and centrifuge indoor test are the two most commonly used methods in geotechnical engineering research. The former greatly increases the difficulty of the test due to factors such as large workload, high cost and long time consumption. In contrast, the latter has significant advantages such as simple test principle and high operability. As an advanced indoor model test method, centrifuge test can truly simulate the existence of gravity field and reproduce the actual stress state of the project. Therefore, it is increasingly widely used in the research of foundation pit engineering related issues. In the research of foundation pit excavation using centrifuge test, manual excavation, automatic robot arm excavation and drainage method are currently mostly used to simulate foundation pit excavation. Among them, manual excavation needs to be carried out under 1g conditions, so the centrifuge needs to be stopped for operation, which greatly reduces the continuity of the test. At the same time, manual operation disturbs the test soil sample greatly; the automatic robot arm needs to occupy a large space and the equipment cost is high; although the drainage method is widely used, the heavy liquid contains toxic components, which will affect the safety of the test personnel. At the same time, the drainage method is cumbersome to operate, and it is difficult to successfully complete the drainage during the test. Therefore, a device for simulating foundation pit excavation in indoor centrifuge tests, which is easy to operate, has little disturbance, low cost and high safety, needs to be developed urgently. Utility Model Content

[0004] The utility model provides a device for simulating foundation pit excavation in an indoor centrifuge test to solve the technical problems existing in the known technology. The device can conveniently, safely and efficiently use a scaled model to reliably simulate the foundation pit excavation process under the action of supergravity provided by the centrifuge.

[0005] The utility model adopts the following technical scheme to solve the technical problems existing in the known technology: a centrifuge test device for simulating foundation pit excavation by using paraffin and laser, comprising a model box and an equipment box, the upper part of the model box is open, a test soil sample is arranged in the model box, a ground-connected wall model is pre-buried in the test soil sample, the ground-connected wall model extends along the entire inner opening width of the model box, and the bottom is suspended above the bottom plate of the model box, a foundation pit model is formed between the ground-connected wall model and the left side wall, front side wall and rear side wall of the model box, the bottom of the foundation pit model is formed by the test soil sample, and solid paraffin is filled in the foundation pit model; the ground-connected wall model is provided with a horizontal support rod perpendicular to it, the horizontal support rod adopts an electric telescopic structure and is installed on the equipment box, and a through hole corresponding to the horizontal support rod is provided on the left side wall of the model box; a laser instrument is provided above the foundation pit model, and the laser instrument is installed on a bracket, the front side wall of the model box is transparent, and a camera is provided in front of the front side wall of the model box.

[0006] Layered excavation marking lines are arranged on the front side wall of the foundation pit model.

[0007] The front side wall of the model box is made of acrylic plate.

[0008] The bracket is fixed on the equipment box.

[0009] The equipment box and the model box adopt an integrally formed structure.

[0010] The advantages and positive effects of the utility model are:

[0011] 1) Compared with manual excavation, there is no need to shut down the centrifuge, which improves the continuity of the test; laser irradiation paraffin is used to simulate excavation, which causes little disturbance to the test soil samples.

[0012] 2) Compared with automated robotic arm excavation, it occupies less space and has lower test costs;

[0013] 3) Compared with the drainage method to simulate foundation pit excavation, the laser irradiation paraffin simulation excavation is easy to operate, non-toxic and harmless.

[0014] In summary, the utility model can accurately simulate the layered excavation of foundation pits, and at the same time, the test process has small disturbance, convenient operation, low cost and high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the utility model;

[0016] Figure 2 It is a longitudinal section view of the utility model before laser irradiation of paraffin to simulate excavation;

[0017] Figure 3 It is a longitudinal section of the utility model after laser irradiation of paraffin to simulate excavation;

[0018] Figure 4 It is a three-dimensional schematic diagram of the model box of the utility model;

[0019] Figure 5 It is a three-dimensional schematic diagram of the equipment box of the utility model;

[0020] Figure 6 It is a three-dimensional schematic diagram of the solid paraffin and ground-connected wall model of the utility model.

[0021] In the figure: 1—model box; 2—foundation pit model; 3—equipment box; 4—front side wall; 5—ground-connected wall model; 6—test soil sample; 7—solid paraffin; 8—camera; 9—bracket; 10—laser; 11—horizontal support rod; 12—layered excavation marking line; 13—bottom of the foundation pit model; 14—through hole. DETAILED DESCRIPTION

[0022] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

[0023] See also Figure 1 to Figure 6 A centrifuge test device for simulating foundation pit excavation using paraffin and laser, comprising a model box 1 and an equipment box 3, wherein the upper part of the model box 1 is open, a test soil sample 6 is arranged in the model box 1, a ground-connected wall model 5 is pre-buried in the test soil sample 6, the ground-connected wall model 5 extends along the entire inner opening width of the model box 1, and the bottom is suspended above the bottom plate of the model box 1, a foundation pit model 2 is formed between the ground-connected wall model 5 and the left side wall, front side wall and rear side wall of the model box 1, and the bottom of the foundation pit model 2 is composed of The test soil sample 6 is formed, and solid paraffin 7 is filled in the foundation pit model 2; the ground-connected wall model 5 is provided with a horizontal support rod 11 perpendicular to it, and the horizontal support rod 11 adopts an electric telescopic structure and is installed on the equipment box 3, and a through hole 14 corresponding to the horizontal support rod is provided on the left side wall of the model box 1; a laser instrument 10 is provided above the foundation pit model 2, and the laser instrument 10 is installed on the bracket 9, the front side wall 4 of the model box 1 is transparent, and a camera 8 is provided in front of the front side wall of the model box 1.

[0024] In this embodiment, a layered excavation marking line 12 is provided on the front side wall of the foundation pit model 2. The front side wall of the model box 1 is made of acrylic plate. The bracket 9 is fixed on the equipment box 3. The equipment box 3 and the model box 1 adopt an integral molding structure with good integrity.

[0025] The process of testing using the above device:

[0026] 1) Install the above device

[0027] The model box 1 and the equipment box 3 are installed in the hanging basket of the centrifuge. The front side wall of the above-mentioned model box 1 is made of transparent material for observing the excavation status. In addition, a layered excavation marking line 12 is marked on the front side wall of the foundation pit model 2 to facilitate the prompting of the excavation depth during the excavation process. At the same time, a through hole 14 for the horizontal support rod is reserved on the left side wall of the model box, which is used for the horizontal support rod to extend after excavation to a predetermined depth to simulate horizontal support.

[0028] According to the actual number of excavation layers, multiple horizontal support rods are set to simulate the horizontal support of the foundation pit. The horizontal support rod 11 is fixed in the equipment box 3, and the installation height should be consistent with the corresponding excavation elevation. Through the through hole 14 reserved on the left wall of the model box, the horizontal support rod 11 can be controlled by an electric motor to extend into the model box 1 to form horizontal support for the ground-connected wall model, thereby completing the simulation of the foundation pit support process.

[0029] The laser instrument bracket 9 is pre-fixed in the equipment box 3. The bracket extends out of the equipment box to a certain height and extends toward the model box 1, forming an inverted L shape. The laser instrument 10 is fixed to the end of the bracket 9. The irradiation direction is from top to bottom. The laser instrument can be turned on or off in time by the test personnel to control the irradiation.

[0030] The model box is pre-filled with test soil samples, and the simulated foundation pit model 2 and the solid paraffin 7 and ground-connected wall model 5 therein are pre-buried at specified positions.

[0031] During installation, it is recommended to first fill the soil sample to the bottom of the foundation pit model, then place the solid paraffin 7 and insert the model ground connecting wall 5, and then fill the remaining space of the model box with the test soil sample to ensure that the soil sample is filled densely and the foundation pit model is set at the predetermined position.

[0032] Step 2: Simulate excavation

[0033] 2.1. After the installation is completed, the high-definition camera 8 is fixed on the centrifuge basket, facing the front of the model box to shoot, and is connected to the control room computer through a line to debug the centrifuge.

[0034] 2.2. Start the centrifuge. When the acceleration reaches the predetermined target acceleration, start the laser 10 to heat the solid paraffin 7. Observe the evaporation of the paraffin through the high-definition camera 8. When the evaporation of the paraffin reaches the set layered excavation mark line 12, turn off the laser 10 and start the corresponding horizontal support rod 11 so that the horizontal support rod just touches the ground-connected wall model 5.

[0035] 2.3. Excavate layer by layer until the bottom of the model foundation pit is reached 13.

[0036] By adopting the above test device, accurate simulation of layered excavation of foundation pit is achieved. At the same time, the test process has small disturbance, convenient operation, low cost and high safety.

[0037] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the scope of protection of the present invention.

Claims

1. A centrifuge test device for simulating foundation pit excavation using paraffin and laser, characterized in that: Including model box and equipment box, The upper part of the model box is open, and a test soil sample is arranged in the model box. A ground-connected wall model is pre-buried in the test soil sample. The ground-connected wall model extends along the entire inner opening width of the model box, and the bottom is suspended above the bottom plate of the model box. A foundation pit model is formed between the ground-connected wall model and the left side wall, front side wall and rear side wall of the model box. The bottom of the foundation pit model is formed by the test soil sample, and the foundation pit model is filled with solid paraffin. The ground-connected wall model is provided with a horizontal support rod perpendicular to it, and the horizontal support rod adopts an electric telescopic structure and is installed on the equipment box. A through hole corresponding to the horizontal support rod is provided on the left side wall of the model box. A laser instrument is provided above the foundation pit model, and the laser instrument is installed on a bracket. The front side wall of the model box is transparent, and a camera is provided in front of the front side wall of the model box.

2. The centrifuge test device for simulating foundation pit excavation using paraffin and laser according to claim 1, characterized in that: Layered excavation marking lines are arranged on the front side wall of the foundation pit model.

3. The centrifuge test device for simulating foundation pit excavation using paraffin and laser according to claim 1, characterized in that: The front side wall of the model box is made of acrylic plate.

4. The centrifuge test device for simulating foundation pit excavation using paraffin and laser according to claim 1, characterized in that: The bracket is fixed on the equipment box.

5. The centrifuge test device for simulating foundation pit excavation using paraffin and laser according to claim 1, characterized in that: The equipment box and the model box adopt an integrally formed structure.

Images