Device for simulating interaction between collapsible loess and pile foundation

Abstract

The utility model provides a device for simulating the interaction of collapsible loess and pile foundation, including model case, model pile body, water stop valve and controllable pressure applying mechanism, the model pile body is arranged in the model case, the controllable pressure applying mechanism is arranged on the top surface of the model pile body, and the water stop valve is installed on the lower part of the model case. Adjusting lower water inlet through a water stop valve at the lower part of the model box, and simulating an underground water level rising condition; the model box is transparent, the instability and deformation states of the soil body in the collapsing process can be visually observed, the rainwater infiltration underground water level rising process in the natural state is simulated, and the authenticity and reliability of the experiment are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of geotechnical engineering pile-soil interaction mode testing, and in particular relates to a device for simulating the interaction between collapsible loess and a pile foundation. Background Art

[0002] Collapsible loess is a special type of soil widely distributed in Northwest, North China and Northeast my country. It has high strength and stability under dry conditions, but will collapse significantly when exposed to water, resulting in a reduction in soil volume and strength, which can lead to engineering disasters such as foundation instability, building cracking and even collapse. Therefore, studying the interaction between collapsible loess and pile foundations, especially the collapsible process under simulated natural conditions, is of great significance for engineering construction and foundation treatment.

[0003] In the prior art, the collapsibility of loess is caused by its pore structure characteristics and the weak bonding structure between soil particles. When loess is soaked in water under its own weight or external load, the soil structure will be rapidly destroyed, resulting in a reduction in the volume of the soil, uneven settlement, and affecting the stability of the foundation. Traditional model test devices mainly focus on the soil collapse deformation process, simulating the settlement and deformation of loess after water immersion. They usually have problems such as complex structure, unstable loading, and limited simulation conditions, making it difficult to fully and accurately reflect the actual performance of the soil under different collapse conditions. Moreover, these devices are usually unable to effectively simulate the process of rainwater infiltration and groundwater level changes under natural conditions, and it is also difficult to observe and record the deformation and instability of the soil through intuitive means.

[0004] Therefore, there is an urgent need for a multifunctional model test device with a wide range of application scenarios, scientific and reliable, so as to study and analyze the specific problems of pile foundation engineering more efficiently, scientifically and in-depth. This device should be able to fully and accurately simulate the interaction process between collapsible loess and pile foundation under natural conditions, especially the behavior under rainwater infiltration and groundwater level changes, so as to provide more accurate experimental data and intuitive observation methods, so as to effectively solve the deficiencies in existing technologies and improve the scientificity and reliability of engineering construction and foundation treatment. Utility Model Content

[0005] The utility model aims to provide a device for simulating the interaction between collapsible loess and pile foundation, so as to overcome the problem that the existing model test device has a complex structure and is difficult to observe and record the deformation and instability of the soil body by intuitive means.

[0006] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0007] A device for simulating the interaction between collapsible loess and pile foundation, characterized in that it comprises a model box, a model pile body is arranged in the model box, and a controllable pressure applying mechanism is arranged at the upper end of the model pile body;

[0008] The lower part of the model box has an opening, and a water stop valve is installed at the opening;

[0009] The model box adopts a transparent structure.

[0010] Furthermore, it also includes a base, and the model box and the controllable pressure applying mechanism are both fixed on the base.

[0011] Furthermore, the model box has an opening at the top and is formed by bonding a plurality of organic glass plates.

[0012] Furthermore, the outer side of the model box is covered with a metal protective shell.

[0013] Furthermore, the metal protective shell includes angle steels arranged at the outer side of the model box and a steel plate at the bottom of the model box.

[0014] Furthermore, the controllable pressure applying mechanism includes a reaction frame and a jack. The reaction frame adopts a door-type structure. A plurality of bolt holes for fixing the jack are opened on the crossbeam of the reaction frame. The bottom of the jack contacts the upper end surface of the model pile body.

[0015] Furthermore, a hydraulic loading device is installed on the reaction frame, and the hydraulic loading device is connected to the jack through an electronic digital dial indicator.

[0016] Furthermore, a strain gauge is attached to the surface of the model pile body, and an earth pressure box is arranged at the bottom of the model pile body.

[0017] Furthermore, the strain gauge is connected to a data acquisition device, and the data acquisition device is also connected to the earth pressure box.

[0018] Furthermore, the data acquisition device is connected to a computer.

[0019] Compared with the prior art, the utility model has the following beneficial technical effects:

[0020] The utility model provides a device for simulating the interaction between collapsible loess and a pile foundation, comprising a model box, a model pile body, a water stop valve and a controllable pressure applying mechanism. The model pile body is arranged in the model box, the controllable pressure applying mechanism is arranged on the top surface of the model pile body, and the water stop valve is installed at the bottom of the model box. The structure is simple and rigid. The water inlet at the bottom is adjusted by the water stop valve at the bottom of the model box to simulate the rising of groundwater level. The model box is transparent, and the instability and deformation state of the soil body in the process of collapsibility can be directly observed, and the process of rising groundwater level due to rainwater infiltration in a natural state is simulated, thereby improving the authenticity and reliability of the experiment.

[0021] Preferably, the device uses a model box formed by bonding high-strength organic glass plates and a metal protective shell welded by angle steels. The metal protective shell limits the deformation of the organic glass plates of the model box, has a simple and stable structure, and is easy to manufacture and operate.

[0022] Preferably, the device is equipped with a high-precision data monitoring system to record strain and pressure changes in real time and provide accurate experimental data.

[0023] The utility model provides an efficient and accurate experimental device for studying the interaction between collapsible loess and pile foundations by optimizing the structural design and integrating an advanced monitoring system, and has important engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a three-dimensional diagram of the overall device of the utility model (excluding the digital display system).

[0025] Figure 2 It is a side view of the model pile and a partial view of the data acquisition motor system of the utility model.

[0026] Figure 3 It is a partial view of the water stop valve of the utility model.

[0027] Figure 4 This is a distribution diagram of bolt holes for connecting the reaction frame and the jack of the utility model.

[0028] Figure 5 This is a diagram of a reaction frame connected to a jack of the utility model.

[0029] Figure 6 This is a diagram of the hydraulic loading device of the utility model.

[0030] Figure 7 This is a diagram of the hydraulic loading system of the utility model.

[0031] In the figure, 1. base; 2. box protective shell; 3. model box; 4. reaction frame; 5. jack; 6. model pile; 7. water stop valve; 8. electronic digital dial indicator; 9. strain gauge; 10. soil pressure box; 11. water stop valve switch; 12. data acquisition equipment; 13. oil inlet pipe; 14. hydraulic loading device; 15. bolt hole; 16. bolt; 17. computer; 18. oil outlet pipe. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0033] In one embodiment of the utility model, a device for simulating the interaction between collapsible loess and pile foundation is provided. Figure 1 As shown, it includes a model box 3, a model pile body 6 and a controllable pressure applying mechanism, wherein the model pile body 6 is arranged inside the model box 3, the controllable pressure applying mechanism is arranged at the upper end of the model pile body 6, and a water stop valve 7 is also arranged at the lower opening position of the model box 3. The water stop valve 7 can be used to adjust the lower water inlet to simulate the rising groundwater level; the model box 3 is transparent, and the instability and deformation state of the soil during the wetting process can be intuitively observed, simulating the process of rainwater infiltration and groundwater level rising under natural conditions, thereby improving the authenticity and reliability of the experiment.

[0034] Specifically, the model box 3 and the controllable pressure applying mechanism are fixed on the base 1 by welding. The model box 3 as a whole is made of five high-strength organic glass plates bonded together. The upper part is open, and the gaps between the glass plates are filled with glass glue. The external side is covered with a metal protective shell 2 of angle steel and a thick steel plate bottom plate. The dimensions of the model box 3 used are 80 cm long, 50 cm wide, and 80 cm high.

[0035] The controllable pressure applying mechanism includes a reaction frame 4, a jack 5 and a hydraulic loading device 14, wherein the hydraulic loading device 14 is installed on the reaction frame 4, the reaction frame 4 adopts a gate-shaped structure, the jack 5 is fixed on the crossbeam of the reaction frame 4, and the hydraulic loading device 14 is connected to the jack 5 through an electronic digital display dial indicator 8.

[0036] like Figure 3 As shown, a water stop valve switch 11 is also installed at the position of the water stop valve 7.

[0037] Example

[0038] A device for simulating the interaction between collapsible loess and pile foundation, comprising a base 1, a box protection shell 2 connected to the base by welding, a model box 3, a reaction frame 4 located on the upper part of the model box, a jack 5, a model pile 6 located in the model box, a water stop valve 7 at the bottom of the model box 3, an electronic digital display dial indicator 8, a strain gauge 9 arranged on the side wall of the model pile, an earth pressure box 10 placed at the bottom of the pile, the strain gauge 9, a data acquisition device 12 connected to the earth pressure box, and a hydraulic loading device 14, wherein the data acquisition device 12 collects data from the strain gauge 9 and the earth pressure box 10 and transmits the collected data to a computer 17 for processing, such as Figure 2 shown.

[0039] The model box 3 is made of five high-strength organic glass plates bonded together, with an opening on the top. The gaps between the glass plates are filled with glass glue, and the external sides are covered with a metal protective shell 2 of angle steel and a thick steel plate bottom plate. The dimensions of the model box used are 80 cm long, 50 cm wide and 80 cm high.

[0040] The reaction frame 4 is a welded combination of I-beams. The I-beam size of the crossbeam is 160mm×88mm×6mm, the side I-beam size is 120mm×68mm×4.5mm, and is equipped with stiffening ribs. The crossbeam of the reaction frame is bolted to the side column through high-strength bolts and connecting plates. Bolt holes 15 are left every 10cm on the side column. Figure 4 As shown, the cross beam of the reaction frame 4 can be moved and fixed.

[0041] The test uses a hydraulic jack 5 for loading, which can be adjusted back in time when the pressure drops. Before the test, the jack 5 needs to be calibrated using a load sensor; it is fixed to the reaction frame 4 by bolts 16, such as Figure 5 shown.

[0042] Twelve strain gauges 9 are symmetrically pasted on the surface of a single model pile 6. The strain data acquisition device uses a DH3816N strain acquisition instrument, the access method is a 1 / 4 bridge, and temperature compensation is set.

[0043] An earth pressure box 10 is arranged at the bottom of the pile to accurately measure the pile end load. The earth pressure box has a measuring range of 10 MPa, a diameter of 16 mm, a thickness of 5 mm, and a full bridge measuring circuit with a bridge resistance of 350Ω.

[0044] The test model pile body 6 is made of organic glass, with a pile length of 65 cm, a pile diameter of 2 cm, a length-to-diameter ratio of 32.5, and a pile spacing of three times the pile diameter (6 cm).

[0045] The hydraulic loading device 14 is connected to the jack 5 through the electronic digital display dial indicator 8. Figure 6 As shown, an oil outlet pipe 18 is connected to the inlet of the hydraulic loading device 14, and an oil inlet pipe 13 is connected to the outlet of the hydraulic loading device 14. Figure 7 shown.

[0046] The detailed working process of this utility model is as follows:

[0047] According to the experimental requirements, loess was filled into the model box layer by layer 3, with each layer being 10 cm thick.

[0048] After each layer is filled, the loess is compacted with a compaction tool until it is filled to a predetermined height. The prefabricated model pile body 6 is inserted into the loess layer in the model box, and an earth pressure box 10 is placed at the bottom of the pile body, and strain gauges 9 are arranged on the side walls of the pile. Ensure that the pile body is installed vertically and stably. Install the crossbeam of the reaction frame 4 to the upper part of the model box 3 and fix it with high-strength bolts 16. Adjust the I-beam crossbeam of the reaction frame to a suitable height and position. Install the hydraulic jack 5 on the reaction frame 4, and the top of the jack 4 contacts the top surface of the model pile body 6, ready to apply vertical load. Connect the strain gauge 9 and the earth pressure box 10 to the data acquisition device 12, ensure that all sensors are working properly, connect the data acquisition device to the computer 17, open the monitoring software, and prepare to record data in real time. Adjust the water stop valve 7 to slowly introduce water to the bottom of the model box to simulate the rise of the groundwater level. Control the speed of water entry, gradually raise the groundwater level, and record the soil collapse. Start the hydraulic jack 4, gradually apply vertical load to the top of the pile, and record the mechanical parameters during the loading process. In each loading stage, stabilize for a period of time to ensure that the data monitoring system records complete strain and pressure data. During the experiment, observe the changes in the soil and pile foundation in the model box 3, and record the soil collapse visually through the plexiglass plate. Record the data of the strain gauge 9 and the soil pressure box 10 at each loading stage, and analyze the interaction between the pile and the soil. Stop loading, gradually unload the pressure of the hydraulic jack 4, and record the mechanical parameters during the unloading process. Tighten the water stop valve switch 11 to close the water stop valve 7, stop the simulation of groundwater level changes, and record the final soil collapse. Export all the data recorded during the experiment for sorting and analysis. Compare the effects of loess collapse on the stress and deformation of pile foundations under different groundwater levels, and summarize the experimental results.

[0049] Through the experimental research of this device, the mechanical behavior and deformation law of loess under different collapsible conditions can be systematically analyzed. These studies provide a scientific basis for the design, construction and treatment of collapsible loess foundations, and ensure the stable use of upper buildings and infrastructure.

[0050] The above is only a preferred specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A device for simulating the interaction between collapsible loess and pile foundation, characterized in that: It comprises a model box (3), wherein a model pile body (6) is arranged in the model box (3), and a controllable pressure applying mechanism is arranged at the upper end of the model pile body (6); The lower part of the model box (3) has an opening, and a water stop valve (7) is installed at the opening; The model box (3) adopts a transparent structure.

2. The device for simulating the interaction between collapsible loess and pile foundation according to claim 1, characterized in that: It also comprises a base (1), and the model box (3) and the controllable pressure applying mechanism are both fixed on the base (1).

3. A device for simulating the interaction between collapsible loess and pile foundation according to claim 1 or 2, characterized in that: The model box (3) has an opening at the top and is formed by bonding a plurality of organic glass plates.

4. A device for simulating the interaction between collapsible loess and pile foundation according to claim 1 or 2, characterized in that: The outer side of the model box (3) is covered with a metal protective shell (2).

5. The device for simulating the interaction between collapsible loess and pile foundation according to claim 4, characterized in that: The metal protective shell (2) comprises an angle steel arranged at an outer side position of the model box (3) and a steel plate at the bottom of the model box (3).

6. The device for simulating the interaction between collapsible loess and pile foundation according to claim 1, characterized in that: The controllable pressure applying mechanism comprises a reaction frame (4) and a jack (5); the reaction frame (4) adopts a door-type structure; a plurality of bolt holes for fixing the jack (5) are opened on the crossbeam of the reaction frame (4); the bottom of the jack (5) contacts the upper end surface of the model pile body (6).

7. The device for simulating the interaction between collapsible loess and pile foundation according to claim 6, characterized in that: A hydraulic loading device (14) is installed on the reaction frame (4), and the hydraulic loading device (14) is connected to the jack (5) via an electronic digital display dial indicator (8).

8. The device for simulating the interaction between collapsible loess and pile foundation according to claim 1, characterized in that: A strain gauge (9) is pasted on the surface of the model pile body (6), and an earth pressure box (10) is arranged at the bottom of the model pile body (6).

9. The device for simulating the interaction between collapsible loess and pile foundation according to claim 8, characterized in that: The strain gauge (9) is connected to a data acquisition device (12), and the data acquisition device (12) is also connected to an earth pressure box (10).

10. The device for simulating the interaction between collapsible loess and pile foundation according to claim 9, characterized in that: The data acquisition device (12) is connected to a computer (17).

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