A guided and enhanced bucket foundation penetration test model device and method

Abstract

The invention discloses a guide-enhanced bucket foundation sinking test model device and method, the device comprises a test system, a water supply system and a negative pressure regulating system; the test system comprises an installation top cover, a foundation guide device, a model box and a bucket foundation; the design of the installation top cover reduces the number of barrel walls, thereby reducing energy consumption; the foundation guide device ensures that the offshore bucket foundation model remains vertical during the penetration process to avoid test errors; an underwater dumping method is used in the model box to prepare saturated soil, which is simple to operate and effectively simulates the sedimentation process of marine soil layers; an anti-filter geotextile is arranged at the water inlet valve port to reduce the water inlet pressure and reduce water surface fluctuations; the perforated bottom plate of the L-shaped wave-breaking plate can weaken the scouring effect of water flow on the soil layer during the test water addition process, and the perforated side wall can eliminate the water waves generated during the water addition process of the water inlet valve; the invention can be used to simulate the installation and sinking process of offshore bucket foundations under marine environments, and improve the excavation-free design calculation method and related construction technology.

Description

Technical Field

[0001] The present invention relates to a guide-enhanced bucket foundation penetration test model device, which can be used to simulate the installation and penetration process of an offshore bucket foundation in a marine environment, study the penetration speed of the offshore bucket foundation, the friction between the bucket wall and the soil, the change in height of the soil plug under different conditions, and the negative pressure required for penetration, and improve the excavation-free design calculation method and related construction technology. Background Art

[0002] With my country's strategic deployment of building a strong maritime nation and developing marine economy, in order to improve the ability of marine resource development and accelerate the pace of marine regional economic development, offshore barrel foundations are widely used in various marine projects such as coastline protection, seaport construction, important island construction, offshore engineering and marine engineering.

[0003] In recent years, offshore barrel foundations have been widely used in marine projects such as oil platform foundations, wind turbine tower foundations, breakwater foundations, and port construction in the offshore oil industry. The offshore barrel foundation installation cover technology used has realized the excavation-free installation of offshore barrel foundations in complex marine environments. It can be used to prevent and control the damage of seabed liquefaction to offshore barrel foundation projects, while speeding up construction, reducing energy loss, reducing construction costs, and shortening construction period.

[0004] In current marine engineering, the installation cap of offshore bucket foundation has not been put into use as a piling device in trenchless construction. Therefore, the relevant trenchless design calculation method and related construction technology need to be improved. Compared with the established model used in the research of theoretical analytical methods and numerical methods, the calculated data has a greater dependence on the selection of calculation parameters; and the engineering measurement method is difficult to achieve real-time monitoring of the dynamic changes of the seabed, and the measurement cost is high, the technical requirements are high, the monitoring is difficult, and it depends on environmental conditions. Given that the model test under normal gravity does not affect the microstructure of the soil, and the penetration speed of the bucket foundation installation device and the friction between the bucket wall and the soil are consistent with the test conditions, it can effectively simulate the sinking process of the bucket foundation in actual engineering to achieve the test purpose.

[0005] Therefore, in order to improve the trenchless design calculation method and related construction technology, determine the negative pressure required for offshore bucket foundation penetration, penetration speed, frictional resistance between the bucket wall and the soil, and the impact of the bucket foundation installation process on the surrounding environment, a simple and effective bucket foundation penetration test model device and method is urgently needed. Summary of the invention

[0006] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a guide-enhanced bucket foundation penetration test model device and method.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] On one hand, the present invention provides a guide-enhanced barrel-type foundation penetration test model device, which includes three parts: a test system, a water supply system and a negative pressure regulating system; the test system includes a mounting top cover, a foundation guide device, a model box and a barrel-type foundation; the water supply system includes a water supply device, a water inlet valve and a wave-breaking plate; the negative pressure regulating system includes a water-gas separation device and a vacuum pump;

[0009] The installation top cover is composed of a top cover body and a level; a first vacuum gauge and an air vent are provided on the top cover body, and a level is fixed on the upper surface; the first vacuum gauge is used to monitor the air pressure state in the barrel foundation in real time; an air extraction valve is provided on the air vent; a first anti-filter geotextile is provided at the bottom of the air vent to prevent mud from entering the conduit and clogging the conduit; the level is used to monitor the horizontal state of the top cover body in real time;

[0010] The barrel-shaped foundation is a PVC barrel without a bottom or a cover; the barrel-shaped foundation is sealed and connected to the top cover body by a rubber ring; the rubber ring is further sealed and connected to the top cover body by a U-shaped clip; at least one row of micro pore water pressure sensors is fixed on the outer wall of the barrel-shaped foundation at a certain distance in the vertical direction;

[0011] The foundation guide device comprises a symmetrically arranged semicircular steel ring, a metal arm, a roller and a rolling track. The rolling track is arranged vertically on the front and rear side walls of the model box. The two semicircular steel rings are detachably connected by a semicircular steel ring connecting device. A plurality of rolling balls are arranged on the inner wall of the semicircular steel ring. The barrel foundation passes through the semicircular steel ring and contacts the rolling balls to reduce the friction force of the foundation guide device on the barrel foundation during the process of penetrating the soil layer. One end of the metal arm is connected to the semicircular steel ring, and the other end is connected to the roller. The roller can roll and stop in the rolling track to adjust the position of the foundation guide device according to the test situation.

[0012] The model box is composed of five pieces of plexiglass at the front, back, left, right and bottom, so that the test situation in the model box can be observed in real time; a water inlet valve is provided at the top of the left side wall of the model box, which can supply water from top to bottom into the model box to prepare saturated soil, the water inlet valve is connected to the water supply device, and a fourth anti-filter geotextile is provided at the water outlet to reduce the impact pressure of water flow; a cushion layer and a certain height of saturated soil are arranged from bottom to top in the model box; above the saturated soil is a certain height of airless water; the saturated soil simulates the seabed; the airless water simulates the seawater environment; a first drain valve is provided at the bottom of the right side wall of the model box for discharging the airless water in the model box; a second anti-filter geotextile is provided at the inner opening of the first drain valve A geotextile is provided at the top of the right side wall of the model box to prevent the liquid from overflowing the model box during the test; a third anti-filter geotextile is provided at the inner opening of the second drainage valve to prevent muddy water from entering the second drainage valve and causing blockage; a hose is connected to the outlet of the second drainage valve to guide the overflow water into the drainage pipe; a wave-breaking plate is provided at the outlet of the water inlet valve, and the overall cross-section of the wave-breaking plate is L-shaped, and a number of wave-breaking holes are evenly spaced and staggered on the vertical baffles and horizontal baffles, and the horizontal baffles are higher than the surface of the saturated soil. The vertical baffles are used to eliminate water waves, and the horizontal baffles are used to reduce the scouring effect of water flow on the soil;

[0013] The water-gas separation device consists of a water-gas separation bottle, a second vacuum gauge, an air inlet and an air outlet; the second vacuum gauge is used to monitor the negative pressure state in the water-gas separation bottle in real time; the air inlet is connected to the air vent installed on the top cover through an air pipe; the air outlet is connected to the vacuum pump through the air pipe, and the vacuum pump is used to control the negative pressure value in the water-gas separation bottle.

[0014] Furthermore, the model box is composed of organic glass. If the strength of the joints of the sides of the model box is insufficient, angle steel can be used for reinforcement; the bottom cushion layer of the model box is composed of a sand and gravel layer, a first wire mesh, a filter geotextile layer and a second wire mesh from bottom to top; the volume of the saturated soil and airless water is determined by the volume of the model box, the height of the barrel foundation and the penetration depth; the saturated soil is obtained by underwater dumping; the size of the installation top cover can be determined by the size of the barrel foundation prototype using a similar principle; the rubber ring of the installation top cover is made separately from the top cover body, and during the test installation process, the rubber ring needs to be coated with vaseline to improve the sealing performance; the cross-section of the rubber ring can be selected in "L" or "U" shape; the number of rolling balls on the foundation guide device can be reasonably adjusted according to the actual engineering conditions.

[0015] Furthermore, the wave-breaking board is a plexiglass board, and the distance between the wave-breaking board and the left side wall of the model box is determined by the water inflow demand to reduce the adverse effect of the drastic fluctuation of the water level caused by the water inflow into the model box on the test; the height of the wave-breaking board is determined by the saturated soil height required for the test.

[0016] Furthermore, the water supply device in the water supply system is used to replenish air-free water in the model box; the fourth anti-filter geotextile at the water outlet of the water inlet valve is used to reduce the water pressure of the water inlet, and the fourth anti-filter geotextile is close to the side wall of the model box, so as to reduce the scouring effect on the bottom saturated soil in the initial stage of filling the model box with water.

[0017] Furthermore, the length of the air inlet pipe in the water-gas separation device in the negative pressure regulating system that penetrates into the bottle should be longer than the length of the air outlet pipe that penetrates into the bottle. The second vacuum gauge is installed on the top of the water-gas separation device to monitor the negative pressure value in the water-gas separation device. During the entire test process, the mud liquid height in the water-gas separation bottle should be lower than the height of the air outlet pipe outlet in the bottle.

[0018] Another aspect of the present invention provides a method for simulating an offshore bucket foundation penetration test using the above device, the method comprising the following steps:

[0019] (1) Assemble the test device: connect the water supply device to the water inlet valve pipeline, and connect the vacuum pump to the air outlet pipeline of the water-gas separation device; adjust the height of the foundation guide device to an appropriate position according to the soil layer height estimated by the test, and use a semicircular steel ring connection device to detachably connect the two semicircular steel rings, and set up a wave-breaking plate on one side of the model box; connect the installation top cover and the barrel foundation through a rubber ring seal; further fix and seal the installation top cover and the rubber ring through a U-shaped clamp; fix at least one row of micro pore water pressure sensors at a certain distance along the vertical direction on the outer wall of the barrel foundation;

[0020] (2) Preparation of saturated soil: from the bottom of the model box, a sand and gravel layer of a certain thickness, a first steel wire mesh, a filter geotextile layer and a second steel wire mesh are laid out in sequence from bottom to top to form a cushion layer with a large porosity ratio; the water inlet valve is opened to slowly add a certain height of air-free water into the model box; then the water inlet valve is closed and the first drainage valve is opened to allow water to slowly flow into the top of the model box and slowly drain out from the bottom, with the water inlet and drainage speeds being roughly equal, and sand is evenly and slowly added into the model box; the sand is allowed to absorb water in the air-free water and settle to form saturated soil; after the saturated soil is prepared, the water inlet valve and the first drainage valve are closed;

[0021] (3) Place the installation cover and the bucket foundation into the foundation guide device, and control it to slowly sink and insert it into the saturated soil to a certain depth, so that a sealed space is formed inside the bucket foundation to ensure a good sealing effect between the inside and outside of the bucket foundation during the penetration test;

[0022] (4) Measure the height of the bucket foundation on saturated soil, the height of water in the bucket foundation, and the height of air before the test;

[0023] (5) Use a sealed air pipe to connect the vent hole on the installation cover and the air inlet of the water-gas separation device; turn on the vacuum pump to make the inside of the bucket foundation and the water-gas separation device in a vacuum state, and continuously apply negative pressure to ensure that the installation cover and the bucket foundation penetrate the soil vertically, stably and evenly until the bucket foundation sinks to the designed elevation, stop pumping, close the exhaust valve and record the corresponding pressure;

[0024] (6) Using a data acquisition instrument, in real time, collect and record the readings of the micro pore water pressure sensor, soil surface displacement sensor and vacuum gauge at the initial state of the test and during the penetration process. At the same time, monitor the displacement of the bucket after stopping the air extraction until the collected data gradually reaches a stable state. The stable state can be determined according to relevant specifications;

[0025] (7) After data collection, the air pipe on the vent is separated from the water-gas separation device, so that the bucket foundation is directly connected to the atmosphere until the air pressure inside and outside the bucket is equal. During the process of dissipation of the negative pressure in the bucket foundation, the displacement of the soil surface in the model box is monitored in real time. After the negative pressure of the bucket foundation is completely dissipated, the verticality of the bucket foundation is tested. After the test is completed, the top cover is installed and separated from the bucket foundation;

[0026] (8) To ensure the accuracy of the test and avoid contingency, the above steps (1) to (7) are repeated, and the collected data are calculated and analyzed to complete the simulated trenchless offshore bucket foundation sinking test, determine the negative pressure required for bucket foundation sinking, penetration speed, friction between the bucket wall and the soil, the rising height of the soil plug in the bucket foundation, the extracted air height and the air-free water height.

[0027] Furthermore, in the step (1), during the process of connecting the installation top cover and the barrel foundation, vaseline can be applied to the rubber ring to ensure the sealing performance of the device; the number and spacing of the micro pore water pressure sensors arranged on the outer wall of the barrel foundation are determined by the depth of the barrel foundation into the soil; if the micro pore water pressure sensor contacts the foundation guide device during the penetration process, it is necessary to temporarily release the guiding effect of the foundation guide device by disassembling the semicircular steel ring connecting device to ensure that the micro pore water pressure sensor does not contact the foundation guide device, and after the micro pore water pressure sensor passes through the foundation guide device, the two semicircular steel rings are re-detachably connected using the semicircular steel ring connecting device; when the barrel foundation reaches the preset elevation, all the micro pore water pressure sensors are located in the soil.

[0028] Furthermore, in the step (2), when the air-free water is initially added, the flow rate needs to be controlled to ensure that the water flows slowly along the side wall of the model box into the bottom of the model box to prevent the generation of bubbles; after the saturated soil is prepared, the saturated soil needs to be left to stand for two to three days to ensure that the air-free water is clear and the saturated soil reaches a certain density and strength.

[0029] Furthermore, in step (5), the range of negative pressure applied is determined by controlling the barrel penetration speed in a preliminary test and the magnitude of the frictional resistance measured in the preliminary test.

[0030] Furthermore, during the test, the design size of the water-gas separation bottle needs to be designed according to the estimated air and water extraction amounts of the test; when the liquid level during the test reaches the warning height, the vacuum pump is turned off and the air outlet is opened to connect to the atmospheric pressure, wherein the warning height is determined by the depth of the air pipe at the air outlet into the bottle.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention adopts a foundation guide device to ensure that the offshore bucket foundation model remains vertical during the penetration process, thereby avoiding direct test errors caused by the bucket foundation in the traditional test model not being able to ensure horizontality and test errors caused by further disturbance of the soil layer caused by correcting the bucket foundation;

[0033] 2. The second drain valve on the top of the side wall of the model box used in the present invention can control the water level, avoid the liquid level rising and the overflow of airless water due to the entry of the model, and realize the objective simulation of the stable and unchanged sea level, so as to ensure that the model test fully simulates the actual situation of the installation of the trenchless offshore bucket foundation, which is conducive to further improving the offshore bucket foundation trenchless design calculation method and related construction technology;

[0034] 3. The present invention adopts underwater dumping method in the model box to prepare saturated soil. The required test instruments and operation are simple. The soil can fully absorb airless water during the sinking process and reach the target density and bearing capacity after a certain period of sedimentation, effectively simulating the sedimentation process of the marine soil layer.

[0035] 4. The anti-filter geotextile is arranged at the water inlet valve port of the present invention, which can reduce the water inlet pressure and reduce the water surface fluctuation; the anti-filter geotextile is close to the inner wall of the model box, and the water flow can be ensured to flow slowly into the bottom of the model box along the inner wall of the model box by adjusting the size of the water valve, thereby reducing the scouring effect on the soil layer and reducing the water surface fluctuation;

[0036] 5. In the present invention, an "L"-shaped cross-section wave-breaking plate is fixed at the water inlet valve port on one side of the model box, and its bottom plate with holes can weaken the scouring effect of water flow on the soil layer during the test water addition process; the side wall with holes of the wave-breaking plate can eliminate the water waves generated during the water addition process of the water inlet valve, thereby preventing the water waves from interfering with the test process and affecting the test results;

[0037] 6. The present invention adopts a water-gas separation device, which can provide a stable negative pressure environment inside the suction bucket type foundation installation device, and can temporarily store a small part of water and sand sucked out from the suction bucket type foundation installation device in the water-gas separation device to avoid directly sucking water into the vacuum pump and damaging the vacuum pump; the negative pressure in the suction bucket type foundation installation device can be accurately controlled by the vacuum gauge in the sealing valve of the water-gas separation device;

[0038] 7. The present invention uses the installation top cover device as an auxiliary installation device for the offshore bucket foundation, enriching the installation method of the offshore bucket foundation. At the same time, compared with the suction bucket installation, the use of the installation top cover can reduce the number of barrel walls subjected to friction during the installation process by half, reduce energy consumption, and improve the calculation formula and related construction technology for installing the bucket foundation without excavation in actual marine engineering using the installation top cover device. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of the structure of a guide-enhanced bucket foundation penetration test model device provided in an embodiment of the present invention;

[0040] Figure 2 A top view of a guide-enhanced bucket foundation penetration test model device provided in an embodiment of the present invention;

[0041] Figure 3 for Figure 2 AA section view;

[0042] Figure 4 A top view of a basic guide device provided in an embodiment of the present invention;

[0043] In the figure: installation top cover 1, top cover body 1-1, level 1-2, U-shaped clip 1-3, rubber ring 1-4, vent 1-5, first anti-filter geotextile 1-6, first vacuum gauge 1-7, foundation guide device 2, rolling ball 2-1, semicircular steel ring 2-2, metal arm 2-3, roller 2-4, rolling track 2-5, semicircular steel ring connecting device 2-6, wave-breaking plate 3, wave-breaking hole 3-1, model box 4, first drain valve 4-1, The second drain valve 4-2, the second anti-filter geotextile 4-3, the third anti-filter geotextile 4-4, the hose 4-5, the saturated soil 4-6, the airless water 4-7, the bottom cushion layer 4-8, the water supply device 5, the water inlet valve 5-1, the fourth anti-filter geotextile 5-2, the barrel foundation 6, the micro pore water pressure sensor 6-1, the water-gas separation device 7, the water-gas separation bottle 7-1, the second vacuum gauge 7-2, the air inlet 7-3, the air outlet 7-4, and the vacuum pump 8. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0045] like Figure 1-4 As shown, a guide-enhanced barrel-type foundation penetration test model device provided in this embodiment includes three parts: a test system, a water supply system and a negative pressure regulating system; the test system includes an installation top cover 1, a foundation guide device 2, a model box 4 and a barrel-type foundation 6; the water supply system includes a water supply device 5, a water inlet valve 5-1 and a wave-breaking plate 3; the negative pressure regulating system includes a water-gas separation device 7 and a vacuum pump 8;

[0046] The installation top cover 1 is composed of a top cover body 1-1 and a level 1-2; the top cover body 1-1 is provided with a first vacuum gauge 1-7 and a vent 1-5 penetrating therethrough, and the level 1-2 is fixed on the upper surface; the first vacuum gauge 1-7 is used to monitor the air pressure state in the barrel foundation 6 in real time; the vent 1-5 is provided with an air extraction valve; the bottom of the vent 1-5 is provided with a first anti-filter geotextile 1-6 to prevent mud from entering the conduit and clogging the conduit; the level 1-2 is used to monitor the horizontal state of the top cover body 1-1 in real time;

[0047] The barrel-shaped foundation 6 is a PVC barrel without a bottom or a cover; the barrel-shaped foundation 6 is sealed and connected to the top cover body 1-1 through a rubber ring 1-4; the rubber ring 1-4 is further sealed and connected to the top cover body 1-1 through a U-shaped clip 1-3; at least one row of micro pore water pressure sensors 6-1 are fixed on the outer wall of the barrel-shaped foundation 6 at a certain distance in the vertical direction;

[0048] The foundation guide device 2 comprises a symmetrically arranged semicircular steel ring 2-2, a metal arm 2-3, a roller 2-4 and a rolling track 2-5, wherein the rolling track 2-5 is arranged vertically opposite to the front and rear side walls of the model box 4, and the two semicircular steel rings 2-2 are detachably connected by a semicircular steel ring connecting device 2-6, and a plurality of rolling balls 2-1 are arranged on the inner wall of the semicircular steel ring 2-2, and the barrel-type foundation 6 passes through the semicircular steel ring 2-2 and contacts with the rolling balls 2-1 to reduce the friction force of the foundation guide device 2 on the barrel-type foundation 6 during the process of penetrating the soil layer; one end of the metal arm 2-3 is connected to the semicircular steel ring 2-2, and the other end is connected to the roller 2-4, and the roller 2-4 can roll and stop in the rolling track 2-5 to adjust the position of the foundation guide device 2 according to the test situation;

[0049] The model box 4 is composed of five pieces of organic glass at the front, back, left, right and bottom, so that the test situation in the model box 4 can be observed in real time. The organic glass is sealed and connected by an organic solvent (such as chloroform solution); a water inlet valve 5-1 is arranged on the top of the left side wall of the model box 4, and water can be supplied from top to bottom into the model box 4 to prepare saturated soil 4-6. The water inlet valve 5-1 is connected to the water supply device 5, and a fourth anti-filter geotextile 5-2 is arranged at the water outlet to reduce the impact pressure of water flow; a cushion layer 4-8 and a certain height of saturated soil 4-6 are arranged from bottom to top in the model box 4; above the saturated soil 4-6 is a certain height of airless water 4-7; the saturated soil 4-6 simulates the seabed; the airless water 4-7 simulates the seawater environment; a first drain valve 4-1 is arranged at the bottom of the right side wall of the model box 4 for discharging the airless water in the model box; the first A second anti-filter geotextile 4-3 is provided at the inner opening of the drain valve 4-1 to prevent mud in the incompletely filtered water from entering the first drain valve 4-1 and causing blockage; a second drain valve 4-2 is provided on the top of the right side wall of the model box 4 to prevent the liquid level from overflowing the model box 4 during the test; a third anti-filter geotextile 4-4 is provided at the inner opening of the second drain valve 4-2 to prevent muddy water from entering the second drain valve 4-2 and causing blockage; a hose 4-5 is connected at the outlet of the second drain valve 4-2 to guide the overflow water into the drainage pipe; a wave-breaking plate 3 is provided at the outlet of the water inlet valve 5-1, and the overall cross-section of the wave-breaking plate 3 is L-shaped, and a number of wave-breaking holes 3-1 are evenly spaced and staggered on the vertical baffle and the horizontal baffle, and the horizontal baffle is higher than the surface of the saturated soil 4-6. The vertical baffle is used to eliminate water waves, and the horizontal baffle is used to reduce the scouring effect of water flow on the soil;

[0050] The water-gas separation device 7 consists of a water-gas separation bottle 7-1, a second vacuum gauge 7-2, an air inlet 7-3 and an air outlet 7-4; the second vacuum gauge 7-2 is used to monitor the negative pressure state in the water-gas separation bottle 7-1 in real time; the air inlet 7-3 is connected to the air vent 1-5 of the mounting top cover 1 through an air pipe; the air outlet 7-4 is connected to the vacuum pump 8 through an air pipe, and the vacuum pump 8 is used to control the negative pressure value in the water-gas separation bottle 7-1.

[0051] Specifically, the model box 4 is composed of organic glass. If the strength of the connection between the sides of the model box 4 is insufficient, angle steel can be used for reinforcement; the bottom cushion layer 4-8 of the model box 4 is composed of a sand and gravel layer, a first wire mesh, a filter geotextile layer and a second wire mesh from bottom to top; the volume of the saturated soil 4-6 and the airless water 4-7 is determined by the volume of the model box 4, the height and penetration depth of the barrel foundation 6; the saturated soil 4-6 is obtained by underwater dumping; the size of the installation top cover 1 can be determined by the size of the barrel foundation prototype using a similar principle; the rubber ring 1-4 of the installation top cover 1 is made separately from the top cover body 1-1, and during the test installation process, the rubber ring 1-4 needs to be coated with vaseline to improve the sealing performance; the cross-section of the rubber ring 1-4 can be selected in "L" or "U" shape; the number of rolling balls 2-1 on the foundation guide device 2 can be reasonably adjusted according to the actual engineering conditions.

[0052] Specifically, the wave-breaking plate 3 is a plexiglass plate, and the distance between the wave-breaking plate 3 and the left side wall of the model box 4 is determined by the water inflow demand to reduce the adverse effect of the drastic fluctuation of the water level caused by the water inflow into the model box 4 on the test; the height of the wave-breaking plate 3 is determined by the height of the saturated soil 4-6 required for the test.

[0053] Specifically, the water supply device 5 in the water supply system is used to replenish the air-free water 4-7 in the model box 4; the fourth anti-filter geotextile 5-2 at the outlet of the water inlet valve 5-1 is used to reduce the water pressure of the water inlet, and the fourth anti-filter geotextile 5-2 is close to the side wall of the model box 4, so as to reduce the scouring effect on the bottom saturated soil 4-6 in the initial stage of water injection into the model box 4.

[0054] Specifically, the length of the air inlet pipe in the water-gas separation device 7 in the negative pressure regulating system that penetrates into the bottle should be longer than the length of the air outlet pipe that penetrates into the bottle. The second vacuum gauge 7-2 is installed on the top of the water-gas separation device 7 to monitor the negative pressure value in the water-gas separation device 7. During the entire test process, the height of the mud liquid in the water-gas separation bottle should be lower than the height of the outlet pipe mouth in the bottle.

[0055] This embodiment provides a method for simulating an offshore bucket foundation penetration test using the above device, comprising the following steps:

[0056] (1) Figure 1The test device is assembled as shown: the water supply device 5 is connected to the water inlet valve 5-1 pipeline, and the vacuum pump 8 is connected to the air outlet 7-4 pipeline of the water-gas separation device 7; according to the soil layer height estimated by the test, the height of the foundation guide device 2 is adjusted to a suitable position, and the two semicircular steel rings 2-2 are detachably connected by a semicircular steel ring connecting device 2-6, and a wave-breaking plate 3 is set up on one side of the model box 4; the installation top cover 1 and the barrel foundation 6 are sealed and connected by a rubber ring 1-4; the installation top cover 1 and the rubber ring 1-4 are further fixed and sealed by a U-shaped clamp 1-3; at least one row of micro pore water pressure sensors 6-1 are fixed on the outer wall of the barrel foundation 6 at a certain distance in the vertical direction;

[0057] Specifically, in the process of connecting the installation top cover 1 and the barrel-type foundation 6, vaseline can be applied on the rubber ring 1-4 to ensure the sealing performance of the device; the number and spacing of the micro pore water pressure sensors 6-1 arranged on the outer wall of the barrel-type foundation 6 are determined by the depth of the barrel-type foundation 6 into the soil; if the micro pore water pressure sensor 6-1 contacts the foundation guide device 2 during the penetration process, it is necessary to temporarily release the guiding effect of the foundation guide device 2 by disassembling the semicircular steel ring connecting device 2-6 to ensure that the micro pore water pressure sensor 6-1 does not contact the foundation guide device 2. After the micro pore water pressure sensor 6-1 passes through the foundation guide device 2, the two semicircular steel rings 2-2 are removably connected using the semicircular steel ring connecting device 2-6; when the barrel-type foundation 6 reaches the preset elevation, all the micro pore water pressure sensors 6-1 are located in the soil.

[0058] (2) Preparation of saturated soil 4-6: from the bottom of the model box 1, a sand and gravel layer of a certain thickness, a first steel wire mesh, a filter geotextile layer and a second steel wire mesh are arranged in sequence from bottom to top to form a cushion layer 4-8 with a larger porosity ratio; the water inlet valve 5-1 is opened to slowly add a certain height of air-free water into the model box 4; then the water inlet valve 5-1 is closed and the first drainage valve 4-1 is opened to allow water to slowly enter the top of the model box 4 and slowly drain from the bottom, and the water inlet and drainage speeds are roughly equal, and sand is evenly and slowly added to the model box 4; the sand is fully absorbed by the air-free water 4-7 and deposited to form saturated soil 4-6; after the saturated soil 4-6 is prepared, the water inlet valve 5-1 and the first drainage valve 4-1 are closed.

[0059] When initially adding the air-free water 4-7, the flow rate needs to be controlled to ensure that the water flows slowly along the side wall of the model box 4 into the bottom of the model box 4 to prevent the generation of bubbles; after the saturated soil 4-6 is prepared, the saturated soil 4-6 needs to be left to stand for two to three days to ensure that the air-free water 4-7 is clear and the saturated soil 4-6 reaches a certain density and strength.

[0060] (3) The installation top cover 1 and the barrel foundation 6 are placed into the foundation guide device 2, and are controlled to slowly sink and insert into the saturated soil 4-6 to a certain depth, so that a sealed space is formed inside the barrel foundation 6 to ensure a good sealing effect between the inside and outside of the barrel foundation 6 during the penetration test.

[0061] (4) Measure the height of the bucket foundation 6 at the saturated soil 4-6 before the test, the height of the water in the bucket foundation, and the height of the air.

[0062] (5) Use a sealed air pipe to connect the vent holes 1-5 on the installation cover 1 and the air inlet 7-3 of the water-gas separation device 7; turn on the vacuum pump 8 to make the inside of the barrel-shaped foundation 6 and the water-gas separation device 7 both in a vacuum state, and continuously apply negative pressure to ensure that the installation cover 1 and the barrel-shaped foundation 6 penetrate the soil vertically, stably, and evenly until the barrel-shaped foundation 6 sinks to the designed elevation, stop pumping, close the pumping valve, and record the corresponding pressure. The range of negative pressure applied is determined by controlling the barrel penetration speed in the preliminary test and the friction resistance measured in the preliminary test.

[0063] (6) The data acquisition instrument is used to collect and record the readings of the micro pore water pressure sensor 6-1, the soil surface displacement sensor and the vacuum gauge in real time at the initial state of the test and during the penetration process. At the same time, the displacement of the bucket is monitored after the air extraction is stopped until the collected data gradually reaches a stable state. The stable state can be determined according to relevant specifications.

[0064] (7) After data collection, the air pipes on the vents 1-5 are separated from the water-gas separation device 7, so that the bucket-type foundation is directly connected to the atmosphere until the air pressure inside and outside the bucket is equal. During the dissipation of the negative pressure in the bucket-type foundation, the displacement of the soil surface in the model box 4 is monitored in real time. After the negative pressure of the bucket-type foundation is completely dissipated, the verticality of the bucket-type foundation 6 is tested. After the test is completed, the top cover 1 is installed and separated from the bucket-type foundation 6.

[0065] (8) To ensure the accuracy of the test and avoid contingency, the above steps (1) to (7) are repeated, and the collected data are calculated and analyzed to complete the simulated trenchless offshore bucket foundation sinking test, determine the negative pressure required for bucket foundation sinking, penetration speed, friction between the bucket wall and the soil, the rising height of the soil plug in the bucket foundation, the extracted air height and the air-free water height.

[0066] Barrel-type foundation Bucket-type foundation Bucket-type foundation During the test, the design size of the water-gas separation bottle needs to be designed according to the estimated air and water extraction amounts of the test; when the liquid level during the test reaches the warning height, the vacuum pump 8 is turned off and the air outlet 7-4 is opened to connect to the atmospheric pressure, wherein the warning height is determined by the depth of the air pipe at the air outlet 7-4 into the bottle.

[0067] The above description is only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanation here, those skilled in the art can associate other specific implementations of the present invention without creative work, and these methods will fall within the protection scope of the present invention.

Claims

1. A guided and enhanced bucket foundation penetration test model device, characterized in that: The invention comprises three parts: a test system, a water supply system and a negative pressure regulating system; the test system comprises a mounting top cover (1), a base guide device (2), a model box (4) and a barrel-shaped base (6); the water supply system comprises a water supply device (5), a water inlet valve (5-1) and a wave-breaking plate (3); the negative pressure regulating system comprises a water-gas separation device (7) and a vacuum pump (8); The installation top cover (1) is composed of a top cover body (1-1) and a level (1-2); a first vacuum gauge (1-7) and a vent (1-5) are provided on the top cover body (1-1), and the level (1-2) is fixed on the upper surface; an air extraction valve is provided on the vent (1-5); and a first anti-filter geotextile (1-6) is provided at the bottom of the vent (1-5); The barrel-shaped foundation (6) is sealed and connected to the top cover body (1-1) via a rubber ring (1-4); the rubber ring (1-4) is further sealed and connected to the top cover body (1-1) via a U-shaped clamp (1-3); at least one row of micro pore water pressure sensors (6-1) are fixed to the outer wall of the barrel-shaped foundation (6) at a certain distance in the vertical direction; The foundation guide device (2) comprises a symmetrically arranged semicircular steel ring (2-2), a metal arm (2-3), a roller (2-4) and a rolling track (2-5); the rolling track (2-5) is arranged vertically on the front and rear side walls of the model box (4); the two semicircular steel rings (2-2) are detachably connected; a plurality of rolling balls (2-1) are arranged on the inner wall of the semicircular steel ring (2-2); the barrel-shaped foundation (6) passes through the semicircular steel ring (2-2) and contacts the rolling balls (2-1) to reduce the friction force of the foundation guide device (2) on the barrel-shaped foundation (6) during the process of penetrating the soil layer; one end of the metal arm (2-3) is connected to the semicircular steel ring (2-2) and the other end is connected to the roller (2-4); the roller (2-4) can roll and stop in the rolling track (2-5) to adjust the position of the foundation guide device (2) according to the test situation; The model box (4) is made of organic glass, and the joints of each side of the model box (4) are reinforced with angle steel; the model box (4) is made of five organic glass pieces at the front, back, left, right and bottom; a water inlet valve (5-1) is provided at the top of the left wall of the model box (4), which can supply water from top to bottom into the model box (4) to prepare saturated soil (4-6); the water inlet valve (5-1) is connected to a water supply device (5), and a fourth anti-filter geotextile (5-2) is provided at the water outlet to reduce the impact pressure of water flow; a bottom cushion layer (4-8) and a certain height of saturated soil (4-6) are arranged from bottom to top in the model box (4); above the saturated soil (4-6) is air-free water (4-7) at a certain height; the saturated soil (4-6) simulates the seabed; The airless water (4-7) simulates the seawater environment; a first drainage valve (4-1) is provided at the bottom of the right side wall of the model box (4); a second anti-filter geotextile (4-3) is provided at the inner opening of the first drainage valve (4-1); a second drainage valve (4-2) is provided at the top of the right side wall of the model box (4); a third anti-filter geotextile (4-4) is provided at the inner opening of the second drainage valve (4-2), and a hose (4-5) is connected at the outlet; a wave-breaking plate (3) is provided at the outlet of the water inlet valve (5-1), the wave-breaking plate (3) having an overall L-shaped cross-section, and a plurality of wave-breaking holes (3-1) are evenly spaced and staggeredly arranged on the vertical baffle and the horizontal baffle, the horizontal baffle is higher than the surface of the saturated soil (4-6) and is used to reduce the scouring effect of water flow on the soil, and the vertical baffle is used to eliminate water waves; The water-gas separation device (7) is composed of a water-gas separation bottle (7-1), a second vacuum gauge (7-2), an air inlet (7-3) and an air outlet (7-4); the air inlet (7-3) is connected to the air vent (1-5) of the mounting top cover (1) through an air pipe; and the air outlet (7-4) is connected to the vacuum pump (8) through an air pipe.

2. A guided and reinforced bucket foundation penetration test model device according to claim 1, characterized in that: The bottom cushion layer (4-8) of the model box (4) is composed of a sandstone layer, a first wire mesh, a filter geotextile layer and a second wire mesh from bottom to top; the volume of the saturated soil (4-6) and the airless water (4-7) is determined by the volume of the model box (4), the height of the bucket foundation (6) and the penetration depth; the saturated soil (4-6) is obtained by an underwater dumping method; the size of the installation top cover (1) is determined by the size of the bucket foundation prototype using a similar principle; the rubber ring (1-4) of the installation top cover (1) is made separately from the top cover body (1-1), and during the test installation process, the rubber ring (1-4) needs to be coated with vaseline to improve the sealing performance; the cross-section of the rubber ring (1-4) can be L-shaped or U-shaped.

3. The guide-enhanced bucket foundation penetration test model device according to claim 1 is characterized in that: The wave-breaking plate (3) is a plexiglass plate. The distance between the wave-breaking plate (3) and the left side wall of the model box (4) is determined by the water inflow requirement, so as to reduce the adverse effect of the violent fluctuation of the water level caused by the water inflow into the model box (4) on the test. The height of the wave-breaking plate (3) is determined by the height of the saturated soil (4-6) required for the test.

4. The guided reinforced bucket foundation penetration test model device according to claim 1 is characterized in that: The water supply device (5) in the water supply system is used to replenish the air-free water (4-7) in the model box (4); the fourth anti-filter geotextile (5-2) at the outlet of the water inlet valve (5-1) is used to reduce the water pressure of the water inlet, and the fourth anti-filter geotextile (5-2) is closely attached to the side wall of the model box (4), so as to reduce the scouring effect on the bottom saturated soil (4-6) in the initial stage of water injection into the model box (4).

5. The guided reinforced bucket foundation penetration test model device according to claim 1 is characterized in that: The length of the air inlet pipe in the water-gas separation device (7) in the negative pressure regulating system extending into the bottle should be longer than the length of the air outlet pipe extending into the bottle. The second vacuum gauge (7-2) is installed on the top of the water-gas separation device (7) to monitor the negative pressure value in the water-gas separation device (7). During the entire test process, the height of the mud liquid in the water-gas separation bottle should be lower than the height of the outlet pipe opening in the bottle.

6. A method for simulating an offshore bucket foundation penetration test using the device according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: (1) Assembling the test device: connecting the water supply device (5) to the water inlet valve (5-1) pipeline, and connecting the vacuum pump (8) to the air outlet (7-4) pipeline of the water-gas separation device (7); adjusting the height of the foundation guide device (2) to a suitable position according to the soil layer height estimated by the test, and detachably connecting the two semicircular steel rings (2-2) using a semicircular steel ring connecting device (2-6), and at the same time setting up a wave-breaking plate (3) on one side of the model box (4); sealingly connecting the installation top cover (1) and the barrel-shaped foundation (6) through a rubber ring (1-4); further fixing and sealing the installation top cover (1) and the rubber ring (1-4) through a U-shaped clamp (1-3); and installing a micro pore water pressure sensor (6-1) on the outer wall of the barrel-shaped foundation (6); (2) preparing saturated soil (4-6): laying a sand and gravel layer, a first steel wire mesh, a filter geotextile layer and a second steel wire mesh in order from the bottom of the model box (4) from bottom to top to form a bottom cushion layer (4-8) with a relatively large porosity ratio; opening the water inlet valve (5-1) and slowly adding a certain height of air-free water into the model box (4); then closing the water inlet valve (5-1) and opening the first drainage valve (4-1) to allow water to slowly flow into the top of the model box (4) and slowly drain from the bottom, with the water inlet and drainage speeds being roughly equal, and uniformly and slowly adding sand into the model box (4); waiting for the sand to absorb water in the air-free water (4-7) and to settle, forming saturated soil (4-6); after the saturated soil (4-6) is prepared, closing the water inlet valve (5-1) and the first drainage valve (4-1); (3) placing the installation top cover (1) and the bucket foundation (6) into the foundation guide device (2), and controlling them to slowly sink and insert into the saturated soil (4-6) to a certain depth, so that a sealed space is formed inside the bucket foundation (6) to ensure that a good sealing effect is formed between the inside and outside of the bucket foundation (6) during the penetration test; (4) Measure the height of the bucket foundation (6) above the saturated soil (4-6) before the test, the height of the water inside the bucket foundation, and the height of the air; (5) Use a sealed air pipe to connect the vent hole (1-5) on the installation cover (1) and the air inlet (7-3) of the water-gas separation device (7); turn on the vacuum pump (8) to make the inside of the barrel-shaped foundation (6) and the water-gas separation device (7) both in a vacuum state, and continuously apply negative pressure to ensure that the installation cover (1) and the barrel-shaped foundation (6) penetrate the soil vertically, stably and evenly until the barrel-shaped foundation (6) sinks to the designed elevation, stop pumping, close the pumping valve and record the corresponding pressure; (6) Using a data acquisition instrument, in real time, collect and record the readings of the micro pore water pressure sensor (6-1), the soil surface displacement sensor and the vacuum gauge in the initial state of the test and during the penetration process, and at the same time, monitor the displacement of the bucket after stopping the air extraction until the collected data gradually reaches a stable state; (7) After data collection is completed, the air pipe on the vent hole (1-5) is separated from the water-gas separation device (7), so that the bucket-shaped foundation is directly connected to the atmosphere until the air pressure inside and outside the bucket is equal. During the process of dissipation of the negative pressure in the bucket-shaped foundation, the displacement of the soil surface in the model box (4) is monitored in real time. After the negative pressure of the bucket-shaped foundation is completely dissipated, the verticality of the bucket-shaped foundation (6) is tested. After the test is completed, the top cover (1) is installed and separated from the bucket-shaped foundation (6); (8) To ensure the accuracy of the test and avoid contingency, the above steps (1) to (7) are repeated, and the collected data are calculated and analyzed to complete the simulated trenchless offshore bucket foundation sinking test, determine the negative pressure required for bucket foundation sinking, penetration speed, friction between the bucket wall and the soil, the rising height of the soil plug in the bucket foundation, the extracted air height and the air-free water height.

7. The method according to claim 6, characterized in that In the step (1), during the process of connecting the installation top cover (1) and the barrel-shaped foundation (6), vaseline can be applied to the rubber ring (1-4) to ensure the sealing performance of the device; the number and spacing of the micro pore water pressure sensors (6-1) arranged on the outer wall of the barrel-shaped foundation (6) are determined by the depth of the barrel-shaped foundation (6) into the soil; if the micro pore water pressure sensor (6-1) contacts the foundation guide device (2) during the penetration process, the guiding effect of the foundation guide device (2) needs to be temporarily released by disassembling the semicircular steel ring connecting device (2-6) to ensure that the micro pore water pressure sensor (6-1) does not contact the foundation guide device (2); after the micro pore water pressure sensor (6-1) passes through the foundation guide device (2), the two semicircular steel rings (2-2) are removably connected using the semicircular steel ring connecting device (2-6); when the barrel-shaped foundation (6) reaches a preset elevation, all the micro pore water pressure sensors (6-1) are located in the soil.

8. The method according to claim 6, characterized in that In the step (2), when the air-free water (4-7) is initially added, the flow rate needs to be controlled to ensure that the water flows slowly along the side wall of the model box (4) into the bottom of the model box (4) to prevent the generation of bubbles; after the saturated soil (4-6) is prepared, the saturated soil (4-6) needs to be left to stand for two to three days to ensure that the air-free water (4-7) is clear and the saturated soil (4-6) reaches a certain density and strength.

9. The method according to claim 6, characterized in that In the step (5), the range of negative pressure applied is determined by controlling the barrel penetration speed in the preliminary test and the frictional resistance measured in the preliminary test.

10. The method according to claim 6, characterized in that During the test, the size of the water-gas separation bottle is designed according to the estimated air and water extraction amounts during the test; when the liquid level during the test reaches the warning height, the vacuum pump (8) is turned off and the air outlet (7-4) is opened to connect to the atmospheric pressure, wherein the warning height is determined by the depth of the air pipe at the air outlet (7-4) penetrating into the bottle.

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