CN112538874A - Guide-enhanced barrel-type foundation penetration test model device and method - Google Patents
Guide-enhanced barrel-type foundation penetration test model device and method Download PDFInfo
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Abstract
The invention discloses a guide-enhanced barrel-shaped foundation penetration test model device and a method, wherein the device comprises a test system, a water supply system and a negative pressure adjusting system; the test system comprises a mounting top cover, a foundation guide device, a model box and a barrel-shaped foundation; the design of mounting the top cover reduces the number of cylinder walls, thereby reducing energy consumption; the foundation guide device ensures that the offshore barrel type foundation model keeps vertical in the injection process, and avoids test errors; the saturated soil is prepared in the model box by adopting an underwater throwing filling method, the operation is simple, and the marine soil layer precipitation process is effectively simulated; the water inlet valve is provided with the reverse filtering geotextile, so that the water inlet pressure can be reduced, and the water surface fluctuation can be reduced; the perforated bottom plate of the L-shaped wave-absorbing plate can weaken the scouring effect of water flow on the soil layer in the water adding process of the test, and the perforated side wall can eliminate water waves generated in the water adding process of the water inlet valve; the invention can be used for simulating the installation and penetration process of an offshore bucket foundation in a marine environment, and perfects the excavation-free design calculation method and the related construction technology.
Description
Technical Field
The invention relates to a guide-enhanced barrel-type foundation penetration test model device which can be used for simulating the installation and penetration processes of an offshore barrel-type foundation in a marine environment, researching the penetration speed of the offshore barrel-type foundation, the frictional resistance of a barrel wall and a soil body, the change height of a soil plug under different conditions and the negative pressure required by penetration, and perfecting an excavation-free design calculation method and a related construction technology.
Background
With the strategic deployment of building oceanic reinforcement and developing oceanic economy in China, in order to improve the development capability of ocean resources and accelerate the development of oceanic regional economy, the offshore bucket foundation is widely applied to various oceanic engineering such as shoreline protection, harbor construction, important island construction, offshore engineering and the like.
In recent years, the offshore bucket foundation is widely applied to ocean engineering such as an oil extraction platform foundation, a wind power tower foundation, a breakwater foundation, seaport construction and the like in the marine oil industry, wherein the adopted technology for installing the top cover of the offshore bucket foundation realizes the excavation-free installation of the offshore bucket foundation in a complex ocean environment, can be used for preventing and treating the damage of seabed liquefaction to the offshore bucket foundation engineering, and simultaneously can accelerate the construction speed, reduce the energy consumption, reduce the construction cost and shorten the construction period.
In the current ocean engineering, the mounting top cover of the offshore bucket foundation is not used as a piling device in excavation-free construction, so that a related excavation-free design calculation method and a related construction technology are still to be perfected, and compared with a theoretical analysis method and a numerical method, a set model is adopted for research, and calculated data has higher dependence on calculation parameter selection; the real-time monitoring of the dynamic change of the seabed is difficult to realize by the method of engineering actual measurement, and the method has the advantages of high actual measurement cost, high technical requirement index, high monitoring difficulty and great dependence on environmental conditions. In view of the fact that the soil body microstructure is not influenced by the normal gravity lower model test, the penetration speed of the barrel-shaped foundation installation device and the frictional resistance between the barrel wall and the soil body are consistent with the test condition, and the sinking and penetrating process of the barrel-shaped foundation in the actual engineering can be effectively simulated so as to achieve the test purpose.
Therefore, in order to perfect a non-excavation design calculation method and a related construction technology, determine negative pressure and penetration speed required by the penetration of an offshore bucket foundation, the magnitude of the frictional resistance between a bucket wall and a soil body, and the influence of the installation process of the bucket foundation on the surrounding environment, a simple and effective bucket foundation penetration test model device and method are urgently needed.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a guide-enhanced barrel-shaped foundation penetration test model device and a guide-enhanced barrel-shaped foundation penetration test method.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the invention provides a guide-enhanced barrel-shaped foundation penetration test model device on one hand, which comprises a test system, a water supply system and a negative pressure adjusting system; the test system comprises a mounting top cover, a foundation guide device, a model box and a barrel-shaped foundation; the water supply system comprises a water supply device, a water inlet valve and a wave-absorbing plate; the negative pressure adjusting system comprises a water-gas separating device and a vacuum pump;
the mounting top cover consists of a top cover main body and a level gauge; the top cover main body is provided with a first vacuum meter and a vent hole which penetrate through the top cover main body, and a level gauge is fixed on the upper surface of the top cover main body; the first vacuum meter is used for monitoring the air pressure state in the barrel-shaped foundation in real time; an air exhaust valve is arranged on the vent hole; the bottom of the vent hole is provided with a first reverse filtering geotextile to prevent slurry from entering the guide pipe and blocking the guide pipe; the gradienter is used for monitoring the horizontal state of the top cover main body in real time;
the barrel-shaped foundation is a PVC barrel without a bottom and a cover; the barrel-shaped foundation is hermetically connected with the top cover main body through a rubber ring; the rubber ring is further connected with the top cover main body in a sealing mode through a U-shaped clamp; at least one row of micro pore water pressure sensors are fixed on the outer wall of the barrel-shaped foundation along the vertical direction at a certain distance;
the barrel-shaped foundation penetrates through the semicircular steel rings and is in contact with the rolling balls, so that the friction force of the foundation guide device during the process that the barrel-shaped foundation penetrates into the soil layer is reduced; one end of the metal arm is connected with the semicircular steel ring, the other end of the metal arm is connected with the roller wheel, and the roller wheel can roll and stop in the rolling track so as to adjust the position of the basic guiding device according to the test condition;
the model box consists of five pieces of organic glass at the front, the back, the left and the right and at the bottom, and the test condition in the model box can be observed in real time; the top of the left side wall of the model box is provided with a water inlet valve which can supply water to the model box from top to bottom to prepare saturated soil, the water inlet valve is connected with a water supply device, and a fourth reverse filter geotextile is arranged at a water outlet to reduce the impact pressure of water flow; a cushion layer and saturated soil with a certain height are distributed in the model box from bottom to top; the upper part of the saturated soil is free of air water at a certain height; the saturated soil simulates a seabed; the waterless simulation seawater environment; a first drainage valve is arranged at the bottom of the right side wall of the model box and used for draining the airless water in the model box; the inner opening of the first drain valve is provided with a second anti-filtration geotextile to prevent incompletely filtered slurry in water from entering the first drain valve to cause blockage; the top of the right side wall of the model box is provided with a second drain valve for preventing the liquid level from overflowing the model box in the test process; the inner opening of the second drain valve is provided with third reverse filter geotextile, so that muddy water is prevented from entering the second drain valve to cause blockage; the outlet of the second drain valve is connected with a hose and is used for guiding overflowed water into a drainage pipeline; the water inlet valve is provided with a water inlet valve, the water inlet;
the water-gas separation device consists of a water-gas separation bottle, a second vacuum meter, a gas inlet and a gas outlet; the second vacuum meter is used for monitoring the negative pressure state in the water-gas separation bottle in real time; the air inlet is communicated with the vent hole of the mounting top cover through an air pipe; the air outlet is communicated with a vacuum pump through an air pipe, and the vacuum pump is used for controlling the negative pressure value in the water-gas separation bottle.
Furthermore, the model box is made of organic glass, and if the strength of the joint of each side of the model box is insufficient, angle steel can be adopted for reinforcement; the bottom cushion layer of the model box consists of a sandstone layer, a first wire mesh, a reverse filtering geotechnical cloth layer and a second wire mesh from bottom to top; the volume of the saturated soil and the water-free volume is determined according to the volume of the model box, the height of the barrel-shaped foundation and the penetration depth; the saturated soil is prepared by an underwater throwing filling method; the size of the mounting top cover can be determined by the size of a barrel-shaped foundation prototype by utilizing a similar principle; the rubber ring for mounting the top cover is made separately from the top cover main body, and vaseline needs to be coated on the rubber ring in the test mounting process to improve the sealing performance; the section of the rubber ring can be in an L shape or a U shape; the number of rolling balls on the basic guiding device can be reasonably adjusted according to the actual engineering situation.
Furthermore, the wave-absorbing plate is an organic glass plate, and the distance between the wave-absorbing plate and the left side wall of the model box is determined by the water inlet requirement, so that the adverse effect of severe fluctuation of the water level caused by water inlet in the model box on the test is reduced; the height of the wave-absorbing plate is determined by the height of saturated soil required by the test.
Further, a water supply device in the water supply system is used for supplementing airless water to the model box; the fourth anti-geotechnological cloth of straining of water intaking valve delivery port department is used for reducing into water hydraulic pressure, just the fourth anti-geotechnological cloth of straining is hugged closely the mold box lateral wall for reduce the scouring action to bottom saturated soil for the initial stage of mold box water injection.
Furthermore, the length of the air inlet pipe in the water-gas separation device in the negative pressure adjusting system extending into the bottle is longer than the length of the air outlet pipe in the bottle, and the second vacuum meter is installed at the top of the water-gas separation device and used for monitoring the negative pressure value in the water-gas separation device; in the whole test process, the height of mud liquid in the water-gas separation bottle is lower than the height of the pipe orifice of the air outlet pipe in the bottle.
The invention also provides a method for simulating an offshore barrel type foundation penetration test by using the device, which comprises the following steps:
(1) assembling a test device: connecting a water supply device with a water inlet valve pipeline, and connecting a vacuum pump with a gas outlet pipeline of a water-gas separation device; adjusting the height of the foundation guide device to a proper position according to the soil layer height estimated by the test, detachably connecting the two semicircular steel rings by using a semicircular steel ring connecting device, and erecting a wave absorbing plate on one side of the model box; connecting the mounting top cover and the barrel-shaped foundation in a sealing manner through a rubber ring; the mounting top cover and the rubber ring are further fixedly sealed through a U-shaped clamp; fixing at least one row of micro pore water pressure sensors on the outer wall of the barrel-shaped foundation along a certain distance in the vertical direction;
(2) preparing saturated soil: sequentially laying a sandstone layer, a first steel wire mesh, a reversed filter geotechnical cloth layer and a second steel wire mesh with certain thickness from bottom to top at the bottom of the model box to form a cushion layer with larger porosity ratio; opening a water inlet valve, and slowly adding airless water with a certain height into the model box; then closing the water inlet valve and opening the first drainage valve to slowly feed water into the top of the model box and slowly drain water from the bottom, wherein the water feeding speed and the water draining speed are approximately equal, and uniformly and slowly adding sandy soil into the model box; forming saturated soil after the sandy soil absorbs water in the airless water and is deposited; after the saturated soil is prepared, closing the water inlet valve and the first drainage valve;
(3) placing the mounting top cover and the barrel-shaped foundation into a foundation guide device, controlling the mounting top cover and the barrel-shaped foundation to slowly sink and insert the mounting top cover and the barrel-shaped foundation into saturated soil to a certain depth, so that a sealed space is formed inside the barrel-shaped foundation, and a good sealing effect is formed between the inside and the outside of the barrel-shaped foundation in the penetration test process;
(4) measuring the height of saturated soil, the height of water in the bucket foundation and the height of air in the bucket foundation before the test;
(5) a sealed air pipe is adopted to connect an air vent on the top cover and an air inlet of the water-gas separation device; opening a vacuum pump to enable the interior of the barrel-shaped foundation and the water-gas separation device to be in a vacuum state, continuously applying negative pressure to ensure that the mounting top cover and the barrel-shaped foundation vertically, stably and uniformly penetrate into a soil body until the barrel-shaped foundation sinks to a designed elevation, stopping air extraction, closing an air extraction valve and recording corresponding pressure intensity;
(6) the data acquisition instrument is used for acquiring and recording the readings of the micro pore water pressure sensor, the soil body surface displacement sensor and the vacuum meter in real time in the initial state of the test and the penetration process, and simultaneously, after stopping pumping, the displacement monitoring on the barrel is carried out until the acquired data gradually reaches a stable state, wherein the stable state can be determined according to relevant specifications;
(7) after data acquisition is finished, separating an air pipe on the vent hole from the water-gas separation device, enabling the barrel-shaped foundation to be directly communicated with the atmosphere until the air pressure inside and outside the barrel is equal, monitoring the surface displacement of the soil body in the model box in real time in the process of negative pressure dissipation in the barrel-shaped foundation, detecting the verticality of the barrel-shaped foundation after the negative pressure dissipation of the barrel-shaped foundation is finished, and separating the mounting top cover from the barrel-shaped foundation after the detection is finished;
(8) in order to ensure the accuracy of the test and avoid the contingency, the steps (1) to (7) are repeated, the collected data are calculated and analyzed, the penetration test of the simulation excavation-free offshore bucket foundation is completed, the negative pressure and the penetration speed required by the penetration of the bucket foundation, the frictional resistance between the bucket wall and the soil body, the rising height of a soil plug in the bucket foundation, the height of extracted air and the height of no water are determined.
Further, in the step (1), in the process of connecting the mounting top cover and the barrel-shaped foundation, vaseline can be coated on the rubber ring to ensure the sealing performance of the device; the number and the spacing of the micro pore water pressure sensors arranged on the outer wall of the barrel-shaped foundation are determined by the soil penetration depth of the barrel-shaped foundation; if the micro pore water pressure sensor is contacted with the basic guiding device in the injection process, the guiding function of the basic guiding device needs to be temporarily relieved by a method for disassembling the semicircular steel ring connecting device so as to ensure that the micro pore water pressure sensor is not contacted with the basic guiding device, and after the micro pore water pressure sensor passes through the basic guiding device, the semicircular steel ring connecting device is used for connecting the two semicircular steel rings in a detachable way; when the barrel-shaped foundation reaches the preset elevation, all the micro pore water pressure sensors are positioned in the soil body.
Further, in the step (2), the flow rate needs to be controlled when no water is initially added, so that water flow is ensured to slowly flow into the bottom of the mold box along the side wall of the mold box, and bubbles are prevented from being generated; after the saturated soil is prepared, the saturated soil needs to be kept stand for two to three days to ensure that no water exists and the saturated soil reaches certain compactness and strength.
Further, in the step (5), the range of the applied negative pressure is determined by controlling the barrel body penetration speed in the pre-test and the measured frictional resistance in the pre-test.
Further, in the test process, the design size of the water-gas separation bottle needs to be designed according to the air and water extraction amount estimated in the test; and when the liquid level in the test process reaches the warning height, the vacuum pump is closed, and the air outlet is opened to communicate with the atmospheric pressure, wherein the warning height is determined by the depth of the air pipe at the air outlet penetrating into the bottle.
Compared with the prior art, the invention has the beneficial effects that:
1. the offshore barrel type foundation model is ensured to be vertical in the penetration process by adopting the foundation guide device, so that direct test errors caused by incapability of ensuring the barrel type foundation to be horizontal in the traditional test model and test errors caused by further disturbance of a soil layer due to deviation rectification of the barrel type foundation are avoided;
2. the second drain valve at the top of the side wall of the model box can control the water level height, so that the liquid level is prevented from rising and no water overflows due to the entering of the model, the objective simulation of the stable and unchangeable sea level is realized, the real situation that the excavation-free offshore bucket foundation is installed is fully simulated by a model test, and the further improvement of the excavation-free design calculation method and the related construction technology of the offshore bucket foundation is facilitated;
3. according to the invention, the saturated soil is prepared in the model box by adopting an underwater throwing filling method, the required test instrument and operation are simple, the soil body can fully absorb the airless water in the sinking process, the target compactness and bearing capacity are achieved after the soil body is settled for a certain period of time, and the settling process of the marine soil layer is effectively simulated;
4. the reverse filtering geotextile is arranged at the water inlet valve, so that the water inlet pressure can be reduced, and the water surface fluctuation can be reduced; the anti-filter geotextile is tightly attached to the inner wall of the mold box, and the water valve is adjusted to ensure that water flow slowly flows into the bottom of the mold box along the inner wall of the mold box, so that the scouring effect on the soil layer is reduced, and the water surface fluctuation is reduced;
5. the invention is on one side of the model box, the intake valve port fixes the wave-absorbing plate with L-shaped cross section, its perforated bottom plate can weaken the scouring action of water flow to the soil layer in the test water-adding process; the side wall of the wave-absorbing plate with the holes can absorb water waves generated in the water adding process of the water inlet valve, so that the water waves are prevented from interfering the test process and influencing the test result;
6. the invention adopts the water-gas separation device, and the water-gas separation device can provide a stable negative pressure environment for the interior of the suction type barrel type foundation installation device, and can temporarily store a small part of water and sandy soil sucked out from the suction type barrel type foundation installation device in the water-gas separation device, so that the water is prevented from being directly sucked into the vacuum pump to damage the vacuum pump; the vacuum gauge in the sealing valve of the water-gas separation device can accurately control the negative pressure in the suction type barrel-shaped foundation installation device;
7. the invention takes the mounting top cover device as an auxiliary mounting device of the offshore bucket foundation, enriches the mounting method of the offshore bucket foundation, simultaneously reduces the number of the cylinder walls subjected to friction in the mounting process by half by using the mounting top cover compared with the suction bucket mounting, reduces the energy consumption, and perfects the excavation-free calculation formula and the related construction technology for mounting the bucket foundation by using the mounting top cover device in the actual ocean engineering.
Drawings
FIG. 1 is a schematic structural diagram of a guide-enhanced barrel-type foundation penetration test model device provided in an embodiment of the present invention;
FIG. 2 is a top view of a guide-enhanced barrel-based penetration test model apparatus provided in an embodiment of the present invention;
FIG. 3 is a cross-sectional view of AA in FIG. 2;
FIG. 4 is a top view of a base guide provided in accordance with an embodiment of the present invention;
in the figure: the device comprises a mounting top cover 1, a top cover main body 1-1, a level gauge 1-2, a U-shaped clamp 1-3, a rubber ring 1-4, a vent hole 1-5, a first inverse filtering geotextile 1-6, a first vacuum gauge 1-7, a foundation guide device 2, a rolling ball 2-1, a semicircular steel ring 2-2, a metal arm 2-3, a rolling wheel 2-4, a rolling track 2-5, a semicircular steel ring connecting device 2-6, a wave absorbing plate 3, a wave absorbing hole 3-1, a model box 4, a first drain valve 4-1, a second drain valve 4-2, a second inverse filtering geotextile 4-3, a third inverse filtering geotextile 4-4, a hose 4-5, saturated soil 4-6, airless water 4-7, a bottom cushion layer 4-8, a water supply device 5, a water inlet valve 5-1, 5-2 parts of fourth reverse filtering geotextile, 6-1 parts of barrel-shaped foundation, 6-1 parts of micro pore water pressure sensor, 7 parts of water-gas separation device, 7-1 parts of water-gas separation bottle, 7-2 parts of second vacuum gauge, 7-3 parts of gas inlet, 7-4 parts of gas outlet and 8 parts of vacuum pump.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
As shown in fig. 1 to 4, the guide-enhanced barrel-type foundation penetration test model device provided by the embodiment includes a test system, a water supply system and a negative pressure adjusting system; the testing system comprises a mounting top cover 1, a foundation guide device 2, a model box 4 and a barrel-shaped foundation 6; the water supply system comprises a water supply device 5, a water inlet valve 5-1 and a wave-absorbing plate 3; the negative pressure regulating system comprises a water-gas separating device 7 and a vacuum pump 8;
the mounting top cover 1 consists of a top cover main body 1-1 and a level meter 1-2; the top cover main body 1-1 is provided with a first vacuum meter 1-7 and a vent hole 1-5 which penetrate through the top cover main body, and a level 1-2 is fixed on the upper surface of the top cover main body; the first vacuum gauge 1-7 is used for monitoring the air pressure state in the barrel type foundation 6 in real time; an air extraction valve is arranged on the vent holes 1-5; the bottom of the vent hole 1-5 is provided with a first reverse filtering geotextile 1-6 to prevent slurry from entering the guide pipe and blocking the guide pipe; the level meter 1-2 is used for monitoring the level state of the top cover main body 1-1 in real time;
the barrel-shaped foundation 6 is a PVC barrel without a bottom and a cover; the barrel-shaped foundation 6 is hermetically connected with the top cover main body 1-1 through a rubber ring 1-4; the rubber ring 1-4 is further connected with the top cover main body 1-1 in a sealing way through 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-shaped foundation 6 along the vertical direction at a certain distance;
the base guiding device 2 comprises semicircular steel rings 2-2, metal arms 2-3, rollers 2-4 and rolling rails 2-5 which are symmetrically arranged, the rolling rails 2-5 are vertically and oppositely arranged on the front side wall and the rear side wall of the model box 4, the two semicircular steel rings 2-2 are detachably connected through semicircular steel ring connecting devices 2-6, a plurality of rolling balls 2-1 are arranged on the inner walls of the semicircular steel rings 2-2, and the barrel-shaped base 6 penetrates through the semicircular steel rings 2-2 and is in contact with the rolling balls 2-1 so as to reduce the friction force of the base guiding device 2 during the process that the barrel-shaped base 6 penetrates into the soil layer; one end of the metal arm 2-3 is connected with the semicircular steel ring 2-2, the other end of the metal arm is connected with the roller 2-4, and the roller 2-4 can roll and stop in the rolling track 2-5 so as to adjust the position of the basic guiding device 2 according to the test condition;
the model box 4 consists of five pieces of organic glass at the front, the back, the left and the right and at the bottom, the test condition in the model box 4 can be observed in real time, and the organic glass is hermetically connected with each other through an organic solvent (such as a chloroform solution); the top of the left side wall of the model box 4 is provided with a water inlet valve 5-1 which can supply water to the model box 4 from top to bottom to prepare saturated soil 4-6, the water inlet valve 5-1 is connected with a water supply device 5, and a fourth reverse filter geotextile 5-2 is arranged at a water outlet to reduce the impact pressure of water flow; a cushion layer 4-8 and saturated soil 4-6 with a certain height are distributed in the model box 4 from bottom to top; 4-7 of airless water with a certain height is arranged above the 4-6 of the saturated soil; 4-6 parts of saturated soil for simulating a seabed; 4-7 times of the airless water simulates a seawater environment; a first drainage valve 4-1 is arranged at the bottom of the right side wall of the model box 4 and used for draining the airless water in the model box; the inner opening of the first drain valve 4-1 is provided with a second inverse filter geotextile 4-3, so that slurry in incompletely filtered water is prevented from entering the first drain valve 4-1 to cause blockage; a second drain valve 4-2 is arranged at the top of the right side wall of the model box 4 and used for preventing the liquid level from overflowing the model box 4 in the test process; the inner opening of the second drain valve 4-2 is provided with a third reverse filter geotextile 4-4 to prevent muddy water from entering the second drain valve 4-2 to cause blockage; the outlet of the second drain valve 4-2 is connected with a hose 4-5 for guiding overflowed water into a drainage pipeline; the water inlet valve 5-1 is provided with a wave eliminating plate 3 at the outlet, the wave eliminating plate 3 is L-shaped in overall section, a plurality of wave eliminating holes 3-1 are arranged on a vertical baffle and a horizontal baffle in a staggered mode at equal intervals, the horizontal baffle is higher than the surface of saturated soil 4-6, the vertical baffle is used for eliminating water waves, and the horizontal baffle is used for reducing the scouring effect of water flow on soil;
the water-gas separation device 7 consists of a water-gas separation bottle 7-1, a second vacuum meter 7-2, a gas inlet 7-3 and a gas outlet 7-4; the second vacuum meter 7-2 is used for monitoring the negative pressure state in the water-gas separation bottle 7-1 in real time; the air inlet 7-3 is communicated with the vent hole 1-5 of the mounting top cover 1 through an air pipe; the air outlet 7-4 is communicated with a vacuum pump 8 through an air pipe, and the vacuum pump 8 is used for controlling the negative pressure value in the water-gas separation bottle 7-1.
Specifically, the model box 4 is made of organic glass, and if the strength of the joint of each side of the model box 4 is insufficient, angle steel can be adopted for reinforcement; the bottom cushion layer 4-8 of the model box 4 consists of a sandstone layer, a first wire mesh, a reverse filter geotechnical cloth layer and a second wire mesh from bottom to top; the volume of the saturated soil 4-6 and the non-aerated water 4-7 is determined according to the volume of the model box 4, the height of the barrel-shaped foundation 6 and the penetration depth; the saturated soil 4-6 is prepared by an underwater throwing filling method; the size of the mounting top cover 1 can be determined by the size of a barrel-shaped foundation prototype by using a similar principle; the rubber ring 1-4 for mounting the top cover 1 is made separately from the top cover main body 1-1, and in the test mounting process, vaseline needs to be coated on the rubber ring 1-4 to improve the sealing performance; the section of the rubber ring 1-4 can be in an L shape or a U shape; the number of the rolling balls 2-1 on the basic guiding device 2 can be reasonably adjusted according to the actual engineering situation.
Specifically, the wave-absorbing plate 3 is an organic glass plate, and the distance between the wave-absorbing plate 3 and the left side wall of the model box 4 is determined by the water inlet requirement, so that the adverse effect of severe fluctuation of the water level caused by water inlet in the model box 4 on the test is reduced; the height of the wave absorbing plate 3 is determined by the height of 4-6 of saturated soil required by the test.
Specifically, a water supply device 5 in the water supply system is used for supplementing airless water 4-7 into the model box 4; the fourth reverse filtering geotextile 5-2 at the water outlet of the water inlet valve 5-1 is used for reducing the water pressure of inlet water, and the fourth reverse filtering geotextile 5-2 is tightly attached to the side wall of the model box 4, so that the scouring effect on the saturated soil 4-6 at the bottom is reduced in the initial stage of water injection for the model box 4.
Specifically, the length of the air inlet pipe penetrating into the bottle in the water-gas separation device 7 in the negative pressure regulation system is longer than the length of the air outlet pipe penetrating into the bottle, and a second vacuum gauge 7-2 is installed at the top of the water-gas separation device 7 and used for monitoring the negative pressure value in the water-gas separation device 7; in the whole test process, the height of mud liquid in the water-gas separation bottle is lower than the height of the pipe orifice of the air outlet pipe in the bottle.
The method for simulating the penetration test of the offshore bucket foundation by using the device comprises the following steps:
(1) the test apparatus was assembled as shown in fig. 1: connecting a water supply device 5 with a water inlet valve 5-1 through a pipeline, and connecting a vacuum pump 8 with an air outlet 7-4 of a water-gas separation device 7 through a pipeline; according to the soil layer height estimated by the test, the height of the foundation guide device 2 is adjusted to a proper position, the two semicircular steel rings 2-2 are detachably connected by the semicircular steel ring connecting devices 2-6, and a wave absorbing plate 3 is erected on one side of the model box 4; the mounting top cover 1 and the barrel-shaped foundation 6 are hermetically connected through rubber rings 1-4; the mounting top cover 1 and the rubber rings 1 to 4 are further fixedly sealed through U-shaped clamps 1 to 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 along the vertical direction at a certain distance;
specifically, in the process of connecting the mounting top cover 1 and the barrel-shaped foundation 6, vaseline can be coated on the rubber rings 1-4 to ensure the sealing performance of the device; the number and the 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 soil penetration depth of the barrel type foundation 6; if the micro pore water pressure sensor 6-1 is contacted with the base guide device 2 in the injection process, the guide effect of the base guide device 2 needs to be temporarily relieved by a method for disassembling the semicircular steel ring connecting device 2-6 so as to ensure that the micro pore water pressure sensor 6-1 is not contacted with the base guide device 2, and after the micro pore water pressure sensor 6-1 passes through the base guide device 2, the semicircular steel ring connecting device 2-6 is used for connecting the two semicircular steel rings 2-2 in a detachable way; when the barrel-shaped foundation 6 reaches the preset elevation, all the micro pore water pressure sensors 6-1 are positioned in the soil body.
(2) Preparing saturated soil 4-6: sequentially laying a sandstone layer, a first steel wire mesh, a reverse filter geotechnical cloth layer and a second steel wire mesh with certain thickness from bottom to top at the bottom of the model box 1 to form a cushion layer 4-8 with larger porosity ratio; opening a water inlet valve 5-1, and slowly adding airless water with a certain height into the model box 4; then closing the water inlet valve 5-1 and opening the first drainage valve 4-1 to ensure that water slowly enters the top of the model box 4 and is slowly drained at the bottom, the water inlet speed and the water drainage speed are approximately equal, and uniformly and slowly adding sandy soil into the model box 4; after the sandy soil absorbs water in the anhydrous water 4-7 and is deposited, forming saturated soil 4-6; and after the saturated soil 4-6 is prepared, closing the water inlet valve 5-1 and the first drainage valve 4-1.
When the non-aerated water is added for 4 to 7 times primarily, the flow rate needs to be controlled, and the water flow is ensured to slowly flow into the bottom of the model box 4 along the side wall of the model box 4 so as to prevent the generation of air bubbles; after the saturated soil 4-6 is prepared, the saturated soil 4-6 is required to be kept stand for two to three days to ensure that no water exists 4-7, the saturated soil 4-6 is clear and reaches certain compactness and strength.
(3) The installation top cover 1 and the barrel-shaped foundation 6 are placed into the foundation guide device 2, and the installation top cover 1 and the barrel-shaped foundation 6 are controlled to slowly sink and are inserted into the saturated soil 4-6 to a certain depth, so that a sealed space is formed inside the barrel-shaped foundation 6, and a good sealing effect is formed between the inside and the outside of the barrel-shaped foundation 6 in the penetration test process.
(4) Before the test, the height of the barrel-shaped foundation 6 in the saturated soil is 4-6, and the height of water and air in the barrel-shaped foundation are measured.
(5) A sealed air pipe is adopted to connect and install the air vent 1-5 on the top cover 1 and the air inlet 7-3 of the water-gas separation device 7; and opening the vacuum pump 8 to ensure that the interior of the barrel-shaped foundation 6 and the water-gas separation device 7 are in a vacuum state, continuously applying negative pressure to ensure that the mounting top cover 1 and the barrel-shaped foundation 6 vertically, stably and uniformly penetrate into the soil body until the barrel-shaped foundation 6 sinks to the designed elevation, stopping air suction, closing an air suction valve and recording the corresponding pressure intensity. The range of the applied negative pressure is determined by controlling the barrel body penetration speed in the pre-test and the measured frictional resistance in the pre-test.
(6) The data acquisition instrument is used for acquiring and recording the readings of the micro pore water pressure sensor 6-1, the soil body surface displacement sensor and the vacuum meter in real time in the initial test state and the penetration process, and meanwhile, after the air exhaust is stopped, the displacement monitoring on the barrel is carried out until the acquired data gradually reach a stable state, wherein the stable state can be determined according to relevant specifications.
(7) After data acquisition is finished, separating the air pipe on the air vent 1-5 from the water-gas separation device 7, enabling the barrel-shaped foundation to be directly communicated with the atmosphere until the air pressure inside and outside the barrel is equal, monitoring the surface displacement of the soil body in the model box 4 in real time in the process of negative pressure dissipation inside the barrel-shaped foundation, detecting the verticality of the barrel-shaped foundation 6 after the negative pressure dissipation of the barrel-shaped foundation is finished, and separating the mounting top cover 1 from the barrel-shaped foundation 6 after the detection is finished.
(8) In order to ensure the accuracy of the test and avoid the contingency, the steps (1) to (7) are repeated, the collected data are calculated and analyzed, the penetration test of the simulation excavation-free offshore bucket foundation is completed, the negative pressure and the penetration speed required by the penetration of the bucket foundation, the frictional resistance between the bucket wall and the soil body, the rising height of a soil plug in the bucket foundation, the height of extracted air and the height of no water are determined.
In the test process of the barrel type foundation and the barrel type foundation, the design size of the water-gas separation bottle needs to be designed according to the air and water extraction amount estimated in the test; and when the liquid level in the test process reaches the warning height, the vacuum pump 8 is closed, and the air outlet 7-4 is opened to communicate with 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.
The foregoing description is only for the purpose of illustrating the principles of the invention and is not to be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.
Claims (10)
1. A guide-enhanced barrel-shaped foundation penetration test model device is characterized by comprising a test system, a water supply system and a negative pressure adjusting system; the testing system comprises a mounting top cover (1), a foundation guide device (2), a model box (4) and a barrel-shaped foundation (6); the water supply system comprises a water supply device (5), a water inlet valve (5-1) and a wave-absorbing plate (3); the negative pressure adjusting system comprises a water-gas separating device (7) and a vacuum pump (8);
the mounting top cover (1) consists of a top cover main body (1-1) and a level meter (1-2); the top cover main body (1-1) is provided with a first vacuum meter (1-7) and a vent hole (1-5) which penetrate through the top cover main body, and a level meter (1-2) is fixed on the upper surface of the top cover main body; an air extraction valve is arranged on the vent hole (1-5); the bottom of the vent hole (1-5) is provided with a first reverse filtering geotextile (1-6);
the barrel-shaped foundation (6) is hermetically connected with the top cover main body (1-1) through a rubber ring (1-4); the rubber ring (1-4) is further connected with the top cover main body (1-1) in a sealing way through 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-shaped foundation (6) along the vertical direction at a certain distance;
the base guiding device (2) comprises semicircular steel rings (2-2), metal arms (2-3), rollers (2-4) and rolling rails (2-5) which are symmetrically arranged, the rolling rails (2-5) are vertically and oppositely arranged on the front side wall and the rear side wall 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 walls of the semicircular steel rings (2-2), the barrel type base (6) penetrates through the semicircular steel rings (2-2) and is in contact with the rolling balls (2-1) so as to reduce the friction force of the base guiding device (2) in the process that the barrel type base (6) penetrates into the soil layer; one end of the metal arm (2-3) is connected with the semicircular steel ring (2-2), the other end of the metal arm is connected with the roller (2-4), and the roller (2-4) can roll and stop in the rolling track (2-5) so as to adjust the position of the basic guiding device (2) according to the test condition;
the model box (4) consists of five organic glasses at the front, the back, the left and the right and at the bottom; the top of the left side wall of the model box (4) is provided with a water inlet valve (5-1) which can supply water to the model box (4) from top to bottom to prepare saturated soil (4-6), the water inlet valve (5-1) is connected with a water supply device (5), and a fourth reverse filter geotextile (5-2) is arranged at a water outlet to reduce the impact pressure of water flow; a cushion layer (4-8) and saturated soil (4-6) with a certain height are distributed in the model box (4) from bottom to top; airless water (4-7) with a certain height is arranged above the saturated soil (4-6); the saturated soil (4-6) simulates a seabed; the water-free (4-7) simulates a seawater environment; a first drain valve (4-1) is arranged at the bottom of the right side wall of the model box (4); a second reverse filter geotextile (4-3) is arranged at the inner opening of the first drainage valve (4-1); a second drain valve (4-2) is arranged at the top of the right side wall of the model box (4); the inner opening of the second drain valve (4-2) is provided with a third reverse filter geotextile (4-4), and the outlet is connected with a hose (4-5); the outlet of the water inlet valve (5-1) is provided with a wave-absorbing plate (3), the whole section of the wave-absorbing plate (3) is L-shaped, a plurality of wave-absorbing holes (3-1) are arranged on the vertical baffle and the horizontal baffle in a staggered mode at equal intervals, the horizontal baffle is higher than the surface of saturated soil (4-6) and used for reducing the scouring effect of water flow on a soil body, and the vertical baffle is used for eliminating water waves;
the water-gas separation device (7) consists of a water-gas separation bottle (7-1), a second vacuum meter (7-2), a gas inlet (7-3) and a gas outlet (7-4); the air inlet (7-3) is communicated with the vent hole (1-5) of the mounting top cover (1) through an air pipe; the air outlet (7-4) is communicated with a vacuum pump (8) through an air pipe.
2. The sink penetration test model device for the guide-enhanced barrel-shaped foundation is characterized in that the model box (4) is made of organic glass, and if the strength of the joint of each side 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) consists of a sandstone layer, a first wire gauze, a reverse filter geotechnical cloth layer and a second wire gauze from bottom to top; the volume of the saturated soil (4-6) and the non-aerated water (4-7) is determined according to the volume of the model box (4), the height of the barrel-shaped foundation (6) and the penetration depth; the saturated soil (4-6) is prepared by an underwater throwing filling method; the size of the mounting top cover (1) can be determined by the size of a barrel-shaped foundation prototype by using a similar principle; the rubber ring (1-4) of the mounting top cover (1) is made separately from the top cover main body (1-1), and in the test mounting process, Vaseline is coated on the rubber ring (1-4) to improve the sealing performance; the section of the rubber ring (1-4) can be selected from L shape or U shape.
3. The guide-enhanced barrel-type foundation penetration test model device is characterized in that the wave-absorbing plate (3) is a plexiglas plate, the distance between the wave-absorbing plate (3) and the left side wall of the model box (4) is determined by the water inlet requirement, so that the adverse effect of severe water level fluctuation caused by water inlet in the model box (4) on the test is reduced; the height of the wave-absorbing plate (3) is determined by the height of saturated soil (4-6) required by the test.
4. The apparatus of claim 1, wherein the water supply device (5) in the water supply system is used for supplying airless water (4-7) to the model box (4); the fourth reverse filtering geotextile (5-2) at the water outlet of the water inlet valve (5-1) is used for reducing the water pressure of inlet water, and the fourth reverse filtering geotextile (5-2) is tightly attached to the side wall of the model box (4), so that the scouring effect on bottom saturated soil (4-6) is reduced in the initial stage of water injection for the model box (4).
5. The guide-enhanced barrel-type foundation penetration test model device as claimed in claim 1, wherein the length of the air inlet pipe penetrating into the bottle of the water-air separation device (7) in the negative pressure regulation system is longer than the length of the air outlet pipe penetrating into the bottle, and a second vacuum gauge (7-2) is installed at the top of the water-air separation device (7) and is used for monitoring the negative pressure value in the water-air separation device (7); in the whole test process, the height of mud liquid in the water-gas separation bottle is lower than the height of the pipe orifice of the air outlet pipe in the bottle.
6. A method of simulating an offshore bucket foundation penetration test using the apparatus of any one of claims 1 to 5, the method comprising the steps of:
(1) assembling a test device: the water supply device (5) is connected with a water inlet valve (5-1) through a pipeline, and the vacuum pump (8) is connected with an air outlet (7-4) of the water-gas separation device (7) through a pipeline; according to the soil layer height estimated by the test, the height of the foundation guide device (2) is adjusted to a proper position, the two semicircular steel rings (2-2) are detachably connected by using semicircular steel ring connecting devices (2-6), and a wave absorbing plate (3) is erected on one side of the model box (4); the mounting top cover (1) is hermetically connected with the barrel-shaped foundation (6) through a rubber ring (1-4); the mounting top cover (1) and the rubber ring (1-4) are further fixedly sealed through a U-shaped clamp (1-3); a micro pore water pressure sensor (6-1) is arranged on the outer wall of the barrel-shaped foundation (6);
(2) preparation of saturated soil (4-6): sequentially arranging a sandstone layer, a first steel wire mesh, a reversed filter geotechnical cloth layer and a second steel wire mesh from bottom to top from the bottom of the model box (1) to form a cushion layer (4-8) with a larger porosity ratio; opening the water inlet valve (5-1), and slowly adding airless water with a certain height into the model box (4); then closing the water inlet valve (5-1) and opening the first water discharge valve (4-1) to enable the top of the model box (4) to slowly feed water and the bottom of the model box to slowly discharge water, wherein the water feeding speed and the water discharging speed are approximately equal, and uniformly and slowly adding sandy soil into the model box (4); after the sandy soil absorbs water in the airless water (4-7) and is deposited, saturated soil (4-6) is formed; after the saturated soil (4-6) is prepared, closing the water inlet valve (5-1) and the first drain valve (4-1);
(3) placing the mounting top cover (1) and the barrel-shaped foundation (6) into the foundation guide device (2), controlling the mounting top cover and the barrel-shaped foundation (6) to slowly sink and insert into the saturated soil (4-6) for a certain depth, so that a sealed space is formed inside the barrel-shaped foundation (6) to ensure that a better sealing effect is formed between the inside and the outside of the barrel-shaped foundation (6) in the penetration test process;
(4) measuring the height of the barrel-shaped foundation (6) in saturated soil (4-6), the height of water in the barrel-shaped foundation and the height of air before the test;
(5) a sealed air pipe is adopted to connect and install the vent holes (1-5) on the top cover (1) and the air inlet (7-3) of the water-gas separation device (7); opening a vacuum pump (8) to ensure that the interior of the barrel-shaped foundation (6) and the water-gas separation device (7) are in a vacuum state, continuously applying negative pressure to ensure that the mounting top cover (1) and the barrel-shaped foundation (6) vertically, stably and uniformly penetrate into a soil body until the barrel-shaped foundation (6) sinks to a designed elevation, stopping air suction, closing an air suction valve and recording corresponding pressure intensity;
(6) the data acquisition instrument is used for acquiring and recording the readings of the micro pore water pressure sensor (6-1), the soil surface displacement sensor and the vacuum meter in real time in the initial state of the test and the penetration process, and simultaneously, the displacement monitoring on the barrel is carried out after the air extraction is stopped until the acquired data gradually reach a stable state;
(7) after data acquisition is finished, separating an air pipe on the vent hole (1-5) from a water-gas separation device (7) to enable the barrel-shaped foundation to be directly communicated with the atmosphere until the air pressure inside and outside the barrel is equal, monitoring the surface displacement of the soil body in the model box (4) in real time in the process of negative pressure dissipation inside the barrel-shaped foundation, detecting the verticality of the barrel-shaped foundation (6) after the negative pressure dissipation of the barrel-shaped foundation is finished, and separating the mounting top cover (1) from the barrel-shaped foundation (6) after the detection is finished;
(8) in order to ensure the accuracy of the test and avoid the contingency, the steps (1) to (7) are repeated, the collected data are calculated and analyzed, the penetration test of the simulation excavation-free offshore bucket foundation is completed, the negative pressure and the penetration speed required by the penetration of the bucket foundation, the frictional resistance between the bucket wall and the soil body, the rising height of a soil plug in the bucket foundation, the height of extracted air and the height of no water are determined.
7. The method according to claim 6, wherein in the step (1), the rubber ring (1-4) is coated with vaseline to ensure the sealing performance of the device during the process of connecting the mounting top cover (1) and the barrel-type foundation (6); the number and the 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 soil penetration depth of the barrel-shaped foundation (6); if the micro pore water pressure sensor (6-1) is contacted with the basic guiding device (2) in the process of penetration, the guiding function of the basic guiding device (2) needs to be temporarily released by a method for disassembling the semicircular steel ring connecting device (2-6) so as to ensure that the micro pore water pressure sensor (6-1) is not contacted with the basic guiding device (2), and after the micro pore water pressure sensor (6-1) passes through the basic guiding device (2), the semicircular steel ring connecting device (2-6) is used for connecting the two semicircular steel rings (2-2) in a detachable way; when the barrel-shaped foundation (6) reaches the preset elevation, all the micro pore water pressure sensors (6-1) are positioned in the soil body.
8. The method according to claim 6, characterized in that in the step (2), the flow rate is controlled during the initial feeding of the non-aerated water (4-7) to ensure that the water slowly flows along the side wall of the mold box (4) to the bottom of the mold box (4) to prevent the generation of air bubbles; after the saturated soil (4-6) is prepared, the saturated soil (4-6) is required to be kept stand for two to three days to ensure that no water (4-7) is clear and the saturated soil (4-6) achieves certain compactness and strength.
9. The method of claim 6, wherein in the step (5), the range of the negative pressure to be applied is determined by controlling a barrel penetration rate in the pre-test and a magnitude of the frictional resistance measured in the pre-test.
10. The method of claim 6, wherein during the testing, the water gas separation cylinder is sized according to the air and water extraction estimated by the testing; and when the liquid level in the test process reaches the warning height, the vacuum pump (8) is closed, and the air outlet (7-4) is opened to communicate with 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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| CN202011511903.8A CN112538874A (en) | 2020-12-18 | 2020-12-18 | Guide-enhanced barrel-type foundation penetration test model device and method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114703909A (en) * | 2022-05-07 | 2022-07-05 | 水利部交通运输部国家能源局南京水利科学研究院 | Offshore wind power cylinder type foundation model test sinking auxiliary device and using method |
| CN114894510A (en) * | 2022-03-24 | 2022-08-12 | 清华大学 | Centrifuge test model in suction bucket foundation installation and operation process |
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2020
- 2020-12-18 CN CN202011511903.8A patent/CN112538874A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114894510A (en) * | 2022-03-24 | 2022-08-12 | 清华大学 | Centrifuge test model in suction bucket foundation installation and operation process |
| CN114703909A (en) * | 2022-05-07 | 2022-07-05 | 水利部交通运输部国家能源局南京水利科学研究院 | Offshore wind power cylinder type foundation model test sinking auxiliary device and using method |
| CN114703909B (en) * | 2022-05-07 | 2022-12-23 | 水利部交通运输部国家能源局南京水利科学研究院 | Offshore wind power cylinder type foundation model test sinking auxiliary device and using method |
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