Double-wellhead suction pile transverse stability experiment system and anti-overturning test method

Abstract

The invention provides a double-wellhead suction pile transverse stability experiment system and an anti-overturning test method.The experiment system comprises an experiment pool, a double-wellhead suction pile model, a hydraulic propeller, a pressure sensor, a tilt angle sensor, a strain gauge, soil pressure boxes and a data acquisition instrument, the experiment pool is filled with an experiment soil layer, and the soil pressure boxes are evenly buried in the experiment soil layer; the double-wellhead suction pile model is arranged in the experimental soil layer and located above the soil pressure box, the hydraulic propeller is fixed to the side wall of the experimental pool, located above the experimental soil layer and horizontally connected with the double-wellhead suction pile model, the pressure sensor is arranged at the output end of the hydraulic propeller, and the tilt angle sensor is arranged on the double-wellhead suction pile model. The strain gauges are evenly distributed on the side wall of the suction pile model, the double-wellhead suction pile model is driven to swing through the hydraulic propeller, the situation that the double-wellhead suction pile used underwater overturns due to eccentric load under the single-wellhead drilling working condition is simulated, and the anti-overturning capacity of the double-wellhead suction pile used underwater is tested.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore oil and gas drilling and production, and particularly relates to a lateral stability experimental system for a dual-well suction pile and an anti-overturning test method. Background Art

[0002] The strength of the shallow unconsolidated formation in deep sea is not high, the soil is soft, and the soil layer is relatively thick. During the deep-water drilling process, collapse is likely to occur. The establishment of a subsea wellhead is a key link in the construction of deep-water drilling projects. The suction wellhead is suitable for building wells on soft seabed, with small installation disturbance and large bearing capacity, and its application in marine resource development is becoming increasingly widespread.

[0003] The suction foundation has been widely used in the pile foundation of offshore engineering structures, but its application as a wellhead foundation structure is still in the exploratory stage. The suction pile, as an underwater mudline foundation structure, can provide huge bearing capacity and can realize the simultaneous installation and lowering of multiple wellheads. The wellhead layout of the suction pile follows the principle of central symmetry, and the dual wells are symmetrically arranged on the center line of the top surface of the suction pile. As the number of wellheads increases, the outer diameter and weight of the suction pile increase exponentially, which puts higher requirements on the lateral stability performance of the structure. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a lateral stability experimental system for a dual-well suction pile and an anti-overturning test method, which drives the dual-well suction pile model to swing through a hydraulic thruster, simulates the situation of overturning caused by eccentric loading of the dual-well suction pile used underwater under the single-well drilling condition, and tests the anti-overturning ability of the dual-well suction pile used underwater.

[0005] In order to solve the above technical problems, the technical solution used in the present invention is as follows:

[0006] The lateral stability experimental system for a dual-well suction pile described in the present invention includes an experimental pool, a dual-well suction pile model, a hydraulic thruster, a pressure sensor, an inclination sensor, a strain gauge, an earth pressure cell, and a data acquisition instrument; the pressure sensor, the inclination sensor, the strain gauge, and the earth pressure cell are all connected to the data acquisition instrument in signal.

[0007] The experimental pool is filled with experimental soil layer, and the earth pressure cells are evenly buried in the experimental soil layer. The buried area of the earth pressure cells is larger than the cross-sectional area of the dual-well suction pile model; the dual-well suction pile model is arranged in the experimental soil layer and above the earth pressure cells, and the earth pressure cells are used to detect the pressure acting on the experimental soil layer in the vertical direction when the dual-well suction pile model tilts.

[0008] The hydraulic thruster is fixed on the side wall of the experimental pool and above the experimental soil layer. The output end of the hydraulic thruster is horizontally connected to the double-well suction pile model. A pressure sensor is arranged at the output end of the hydraulic thruster; the pressure sensor is used to detect the pressure exerted by the hydraulic thruster on the double-well suction pile model.

[0009] The inclination sensor is arranged on the double-well suction pile model. The inclination sensor is used to detect the inclination change of the double-well suction pile model; the strain gauges are evenly distributed on the side wall of the suction pile model. The strain gauges are used to detect the pressure on the periphery of the double-well suction pile model.

[0010] Preferably, it further includes a force transfer rod and a force transfer sleeve. The force transfer sleeve is fixed on the top of the double-well suction pile model; one end of the force transfer rod is connected to the force transfer sleeve, and the other end of the force transfer rod is connected to the output end of the hydraulic thruster.

[0011] Preferably, the double-well suction pile model includes a cylinder body and a top cover. The top cover is arranged on the top of the cylinder body; two inner conduits are arranged in the cylinder body. The two inner conduits are symmetrically arranged about the axis of the cylinder body, and the axes of the two inner conduits are parallel to the axis of the cylinder body; the bottom surface of the inner conduit is flush with the bottom surface of the cylinder body, and the horizontal height of the top end of the inner conduit is above the top cover.

[0012] Preferably, the force transfer sleeve includes a force receiving hole, a spherical hinge joint and a sleeve body; the force receiving hole is arranged on one side of the sleeve body, and the force receiving hole is connected to the sleeve body through the spherical hinge joint; the sleeve body is arranged at the top end of the inner conduit; the force receiving hole has the same horizontal height as the output end of the hydraulic thruster, and the force transfer rod connects the force receiving hole and the output end of the hydraulic thruster.

[0013] Preferably, the thickness of the experimental soil layer is greater than the height of the double-well suction pile model, and the thickness of the experimental soil layer is less than the depth of the experimental pool.

[0014] Another object of the present invention is to provide a method for testing the anti-overturning of a double-well suction pile, which is realized through a double-well suction pile lateral stability experimental system, and includes the following steps:

[0015] S1. Pre-install the earth pressure cell, strain gauges and inclination sensors.

[0016] S2. Place the double-well suction pile model, install the force transfer sleeve, and connect the force transfer sleeve and the output end of the hydraulic thruster through the force transfer rod.

[0017] S3. Control the hydraulic thruster to push forward horizontally. The inclination sensor and the pressure sensor monitor and record the inclination and the pressure magnitude of the double-well suction pile model in real time; until the inclination change of the double-well suction pile model exceeds 1°, proceed to S4.

[0018] S4. Obtain the ultimate anti-overturning moment M of the double-well suction pile model R .

[0019] S5. Calculate the anti-overturning safety factor η of the double-well suction pile model through η = M R / M O ; where M O is the overturning moment generated by the lateral load on the double-well suction pile model.

[0020] S6. Determine whether the current anti-overturning safety factor of the double-well suction pile model is greater than or equal to the preset safety factor; if so, it is determined that the double-well suction pile model does not overturn when subjected to the lateral load; if not, it is determined that the double-well suction pile model will overturn when subjected to the lateral load.

[0021] Preferably, S4 specifically includes the following steps:

[0022] S4.1. Calculate the anti-overturning moment M provided by the passive earth pressure through the formula ; where ε Ep is the recorded data of the strain gauge; E is the elastic modulus of the barrel wall of the double-well suction pile model; l1 is the average length of the strain gauge pasting range; h1 is the average width of the strain gauge pasting range; d j is the vertical distance from the center of the strain gauge to the bottom surface of the double-well suction pile model; j is the strain gauge number, j = 1, 2... m. j

[0023] S4.2. Calculate the anti-overturning moment M provided by the frictional resistance through the formula ; where δ is the friction coefficient between the pile and the soil; r f is the horizontal projection distance from the center of the strain gauge to the rotation axis; the rotation axis is the axis of the bottom surface of the barrel of the double-well suction pile model, and the rotation axis is perpendicular to the lateral load. j

[0024] S4.3. Calculate the anti-overturning moment M provided by the ultimate bearing capacity of the foundation through the formula ; where p b is the recorded data of the earth pressure cell; l2 is the average length of the earth pressure cell embedding range; l2 is the average width of the earth pressure cell embedding range; r i is the horizontal projection distance from the center of the earth pressure cell to the rotation axis; i is the earth pressure cell number, i = 1, 2... n. i

[0025] S4.4. Calculate the ultimate anti-overturning moment M of the double-well suction pile through the formula M R = M Ep + M f + M b ; R .

[0026] Preferably, S1 specifically includes the following steps:

[0027] S1.1. Bury a number of earth pressure cells in the experimental soil layer. The earth pressure cells are evenly distributed. Record the number and corresponding position of each earth pressure cell. Each earth pressure cell is signal-connected to a data acquisition instrument.

[0028] S1.2. Evenly paste strain gauges on the outer side of the double-well suction pile model cylinder wall. Record the number and corresponding position of each strain gauge. Each strain gauge is signal-connected to a data acquisition instrument.

[0029] S1.3. Install an inclination sensor at the axis center of the top of the double-well suction pile model. The inclination sensor is signal-connected to a data acquisition instrument.

[0030] Preferably, S2 specifically includes the following steps:

[0031] S2.1. Vertically place the double-well suction pile model into the experimental soil layer, so that the axis of the inner conduit of the double-well suction pile model and the axis where the output end of the hydraulic thruster is located are in the same plane; after the double-well suction pile model is placed, obtain the data of the inclination sensor; if the current inclination angle of the double-well suction pile model is not zero, then re-place the double-well suction pile model; if the current inclination angle of the double-well suction pile model is zero, then proceed to S2.3.

[0032] S2.3. Install the force transfer sleeve on the top of the inner conduit close to the hydraulic thruster, with the force receiving hole facing the hydraulic thruster, and the axis of the force receiving hole and the axis where the output end of the hydraulic thruster is located are on the same horizontal line.

[0033] The beneficial effects of the double-well suction pile lateral stability experimental system according to the present invention compared with the prior art are mainly reflected in: the hydraulic thruster is used to drive the double-well suction pile model to swing, simulating the situation of the eccentric load and overturning of the double-well suction pile used underwater in the single-well drilling condition, and testing the anti-overturning ability of the double-well suction pile used underwater. The inclination angle of the double-well suction pile model is detected by the inclination sensor to control the overturning angle of the double-well suction pile model; the data of the double-well suction pile model at different overturning angles are detected by the strain gauges and earth pressure cells; furthermore, by changing the force applied by the hydraulic thruster on the double-well suction pile model, the state of the double-well suction pile model at different overturning angles can be adjusted, and the data changes of the double-well suction pile model at different overturning angles can be obtained; in this way, the accuracy of the simulation can be improved.

[0034] Connect the hydraulic thruster and the double-well suction pile model through a load transfer bar and a load transfer sleeve. Set the cooperation between the load transfer bar and the load transfer sleeve for stress transfer, reduce stress concentration, and avoid deformation of the double-well suction pile model. Set the force-receiving holes and the hydraulic thruster at the same horizontal height to ensure the transfer effect of the lateral load; at the same time, the load transfer sleeve is sleeved on the inner conduit, and the inner conduit is parallel to the axis of the cylinder body. The axes of the load transfer sleeve, the inner conduit, and the cylinder body are in the same plane; furthermore, when the hydraulic thruster acts; the hydraulic thruster provides a lateral load in the plane where the axis of the cylinder body is located.

[0035] The present invention drives the double-well suction pile model to swing through a hydraulic thruster, simulates the situation of the double-well suction pile used underwater being overturned due to eccentric loading under the single-well drilling condition, and tests the anti-overturning ability of the double-well suction pile used underwater.

[0036] The beneficial effects of the anti-overturning test method of the double-well suction pile described in the present invention compared with the prior art are mainly reflected in: first driving the inclination angle of the double-well suction pile model to be overturned to be greater than 1°, ensuring that the double-well suction pile model is overturned, and then obtaining the moment when the double-well suction pile model is overturned; furthermore, the anti-overturning safety factor of the double-well suction pile model in the overturned state can be obtained, and it can be judged whether the double-well suction pile model will be overturned when subjected to a lateral load; thus, the anti-overturning ability of the double-well suction pile can be tested.

[0037] In the calculation method of the ultimate anti-overturning moment of the double-well suction pile model, the double-well suction pile model and the experimental soil layer are regarded as a moving object; when the lateral load received by the double-well suction pile model reaches the limit, the cylinder body of the double-well suction pile model rotates around the rotation axis; therefore, the ultimate anti-overturning moment of the double-well suction pile is determined by the anti-overturning moment provided by the passive earth pressure, the anti-overturning moment provided by the frictional resistance, and the anti-overturning moment provided by the ultimate bearing capacity of the foundation for the double-well suction pile.

[0038] At the same time, strain gauges are used to detect the pressure on the periphery of the double-well suction pile model, and the anti-overturning moment provided by the passive earth pressure and the anti-overturning moment provided by the frictional resistance are calculated through the data of the strain gauges; earth pressure cells are used to detect the pressure on the experimental soil layer in the vertical direction when the double-well suction pile model tilts, and the anti-overturning moment provided by the ultimate bearing capacity of the foundation is calculated through the earth pressure cells; the method is simple. Description of the Drawings

[0039] The present invention will become clearer about the above and other objects, features, and advantages through the preferred embodiments of the present invention shown in the drawings. The same reference numerals in all the drawings indicate the same parts, and the drawings are not deliberately drawn to scale in actual size, and the focus is on showing the gist of the present invention.

[0040] Figure 1 This is a schematic diagram of the experimental system of the present invention.

[0041] Figure 2 This is a schematic diagram of the double-well suction pile model in the experimental system of the present invention.

[0042] Figure 3 This is a schematic diagram of the force transfer sleeve in the experimental system of the present invention.

[0043] Figure 4 This is a bottom view of the force transfer sleeve in the experimental system of the present invention.

[0044] Figure 5 This is a schematic diagram of the strain gauges arranged on the double-well suction pile model in the experimental system of the present invention.

[0045] Figure 6 This is a schematic diagram of the distribution of the strain gauges in the experimental system of the present invention.

[0046] Figure 7 This is a schematic diagram of the distribution of the earth pressure cells in the experimental system of the present invention.

[0047] Figure 8 This is a schematic diagram of the change in the rotation of the double-well suction pile model under the action of a lateral load in the experimental system of the present invention.

[0048] Description of the drawings: 1 - experimental pool, 2 - experimental soil layer, 3 - double-well suction pile model, 31 - rotation axis, 4 - hydraulic pusher, 5 - pressure sensor, 6 - force transfer rod, 7 - force transfer sleeve, 8 - inclination sensor, 9 - hydraulic station, 10 - data acquisition instrument, 11 - strain gauge, 12 - earth pressure cell; 301 - cylinder body, 302 - top cover, 303 - inner conduit; 701 - force-bearing hole, 702 - sleeve body, 703 - bolt, 704 - spherical hinge joint. Detailed implementation manners

[0049] The technical solution of the present invention will be further described in detail below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it. However, the embodiments cited are not intended to limit the present invention. In this embodiment, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0050] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component and integrated with it, or there may be an intermediate component at the same time. The terms "installed", "one end", "the other end" and similar expressions used in the present invention are only for illustrative purposes.

[0051] This embodiment provides a lateral stability experimental system for a double-well suction pile, as Figure 1-5 shown; it includes an experimental pool 1, a double-well suction pile model 3, a hydraulic thruster 4, a force transfer rod 6, a force transfer sleeve 7, a pressure sensor 5, an inclination sensor 8, a strain gauge 11, an earth pressure cell 12 and a data acquisition instrument 10; the pressure sensor 5, the inclination sensor 8, the strain gauge 11 and the earth pressure cell 12 are all signal-connected to the data acquisition instrument 10. The hydraulic thruster 4 is connected to a hydraulic station 9.

[0052] The experimental pool 1 is filled with an experimental soil layer 2, and the earth pressure cells 12 are evenly buried in the experimental soil layer 2. The buried area of the earth pressure cells 12 is larger than the cross-sectional area of the double-well suction pile model 3; the double-well suction pile model 3 is arranged in the experimental soil layer 2 and above the earth pressure cells 12. The earth pressure cells 12 are used to detect the pressure acting on the experimental soil layer 2 in the vertical direction when the double-well suction pile model 3 tilts.

[0053] The hydraulic thruster 4 is fixed on the side wall of the experimental pool 1 and above the experimental soil layer 2. The output end of the hydraulic thruster 4 is connected to one end of the force transfer rod 6, and the other end of the force transfer rod 6 is connected to the force transfer sleeve 7; the force transfer sleeve 7 is arranged on the top of the double-well suction pile model 3; the hydraulic thruster 4 is horizontally connected to the double-well suction pile model 3, and the pressure sensor 5 is arranged at the output end of the hydraulic thruster 4; the pressure sensor 5 is used to detect the pressure exerted by the hydraulic thruster 4 on the double-well suction pile model 3.

[0054] The inclination sensor 8 is arranged on the double-well suction pile model 3, and the inclination sensor 8 is used to detect the inclination change of the double-well suction pile model 3; the strain gauges 11 are evenly distributed on the side wall of the suction pile model, and the strain gauges 11 are used to detect the pressure on the circumferential side of the double-well suction pile model 3.

[0055] The double-well suction pile model 3 includes a cylinder body 301 and a top cover 302, and the top cover 302 is arranged on the top of the cylinder body 301; two inner conduits 303 are arranged in the cylinder body 301, and the two inner conduits 303 are symmetrically arranged about the axis of the cylinder body 301, and the axes of the two inner conduits 303 are parallel to the axis of the cylinder body 301; the bottom surface of the inner conduit 303 is flush with the bottom surface of the cylinder body 301, and the horizontal height of the top end of the inner conduit 303 is above the top cover 302.

[0056] The force transmission sleeve 7 includes a force receiving hole 701, a spherical hinge joint 704 and a sleeve body 702; the force receiving hole 701 is arranged on one side of the sleeve body 702, and the force receiving hole 701 is connected to the sleeve body 702 through the spherical hinge joint 704; the sleeve body 702 is arranged at the top end of the inner conduit 303; the force receiving hole 701 has the same horizontal height as the output end of the hydraulic thruster 4, and the force transmission rod 6 connects the force receiving hole 701 and the output end of the hydraulic thruster 4.

[0057] In a preferred embodiment, the sleeve body 702 is a pipe clamp. There is an opening on the side of the sleeve body 702 away from the spherical hinge joint 704. There are two clamping pieces on the opening, and through holes are arranged on the clamping pieces; the bolt 703 passes through the two through holes and is connected to the nut; the sleeve body 702 is clamped on the inner conduit 303 by the cooperation of the bolt 703 and the nut.

[0058] In a preferred embodiment, the thickness of the experimental soil layer 2 is greater than the height of the double-well suction pile model 3, and the thickness of the experimental soil layer 2 is less than the depth of the experimental pool 1.

[0059] This lateral stability experimental system; the hydraulic thruster 4 is used to drive the double-well suction pile model 3 to swing, simulate the situation of the eccentric load and overturning of the double-well suction pile used underwater under the single-well drilling condition, and test the anti-overturning ability of the double-well suction pile used underwater. The inclination angle of the double-well suction pile model 3 is detected by the inclination sensor 8 to control the overturning angle of the double-well suction pile model 3; the data of the double-well suction pile model 3 at different overturning angles are detected by the strain gauge 11 and the earth pressure cell 12; furthermore, by changing the force applied by the hydraulic thruster 4 on the double-well suction pile model 3, the state of the double-well suction pile model 3 at different overturning angles can be adjusted, and the data change of the double-well suction pile model 3 at different overturning angles can be obtained; in this way, the accuracy of the simulation can be improved.

[0060] The hydraulic thruster 4 and the double-well suction pile model 3 are connected through the force transmission rod 6 and the force transmission sleeve 7. The force transmission rod 6 and the force transmission sleeve 7 are set to cooperate for stress transmission, reduce stress concentration, and avoid deformation of the double-well suction pile model 3. The force receiving hole 701 and the hydraulic thruster 4 with the same horizontal height are set to ensure the transmission effect of the lateral load; at the same time, the force transmission sleeve 7 is sleeved on the inner conduit 303, the inner conduit 303 is parallel to the axis of the cylinder body 301, and the axis of the force transmission sleeve 7, the axis of the inner conduit 303 and the axis of the cylinder body 301 are in the same plane; furthermore, when the hydraulic thruster 4 acts; the hydraulic thruster 4 provides a lateral load in the plane where the axis of the cylinder body 301 is located.

[0061] The present invention also provides a method for testing the anti-overturning of a double-well suction pile, which is realized through the double-well suction pile lateral stability experimental system, and includes the following steps:

[0062] S1. Pre-install the earth pressure cell 12, strain gauge 11 and inclinometer 8.

[0063] S2. Place the double-well suction pile model 3, install the force transfer sleeve 7, and connect the force transfer sleeve 7 and the output end of the hydraulic pusher 4 through the force transfer rod 6.

[0064] S3. Control the hydraulic pusher 4 to advance forward and laterally. The inclinometer 8 and pressure sensor 5 monitor and record the inclination angle and the magnitude of the pressure received by the double-well suction pile model 3 in real time; until the inclination angle change of the double-well suction pile model 3 exceeds 1°, then proceed to S4.

[0065] S4. Obtain the ultimate anti-overturning moment M of the double-well suction pile model 3 R 。

[0066] S5. Through η = M R / M O ; Calculate the anti-overturning safety factor η of the double-well suction pile model 3; M O is the overturning moment generated by the lateral load on the double-well suction pile model 3.

[0067] S6. Judge whether the current anti-overturning safety factor of the double-well suction pile model 3 is greater than or equal to the preset safety factor; if so, judge that the double-well suction pile model 3 will not overturn when subjected to the lateral load; if not, judge that the double-well suction pile model 3 will overturn when subjected to the lateral load. In a preferred embodiment, the preset safety factor is 1.6.

[0068] The anti-overturning safety factor of the suction pile is usually set to 1.6

[0069] In the above method:

[0070] S1 specifically includes the following steps:

[0071] S1.1. Bury several earth pressure cells 12 in the experimental soil layer 2. The earth pressure cells 12 are evenly distributed. Record the number and corresponding position of each earth pressure cell 12. Each earth pressure cell 12 is signal-connected to the data acquisition instrument 10.

[0072] S1.2. Evenly paste strain gauges 11 on the outer side of the barrel wall of the double-well suction pile model 3. Record the number and corresponding position of each strain gauge 11. Each strain gauge 11 is signal-connected to the data acquisition instrument 10.

[0073] S1.3. Install an inclinometer 8 at the axis of the top of the double-well suction pile model 3. The inclinometer 8 is signal-connected to the data acquisition instrument 10.

[0074] S2 specifically includes the following steps:

[0075] S2.1. Vertically place the double-well suction pile model 3 into the experimental soil layer 2, such that the axis of the inner conduit 303 of the double-well suction pile model 3 and the axis where the output end of the hydraulic thruster 4 is located are in the same plane. After the double-well suction pile model 3 is placed, obtain the data of the inclination sensor 8. If the current inclination of the double-well suction pile model 3 is not zero, re-place the double-well suction pile model 3. If the current inclination of the double-well suction pile model 3 is zero, proceed to S2.3.

[0076] S2.3. Install the force transmission sleeve 7 at the top of the inner conduit 303 close to the hydraulic thruster 4, with the direction of the force receiving hole 701 facing the hydraulic thruster 4, and the axis of the force receiving hole 701 and the axis where the output end of the hydraulic thruster 4 is located being on the same horizontal line.

[0077] S4 specifically includes the following steps:

[0078] S4.1. Calculate the anti-overturning moment M provided by the passive earth pressure through the formula ; ε Ep is the recorded data of the strain gauge 11; E is the elastic modulus of the barrel wall of the double-well suction pile model 3; l1 is the average length of the pasting range of the strain gauge 11; h1 is the average width of the pasting range of the strain gauge 11; d j is the vertical distance from the center of the strain gauge 11 to the bottom surface of the double-well suction pile model 3; j is the strain gauge 11 number, j = 1, 2... m. j is the vertical distance from the center of the strain gauge 11 to the bottom surface of the double-well suction pile model 3; j is the strain gauge 11 number, j = 1, 2... m.

[0079] S4.2. Calculate the anti-overturning moment M provided by the frictional resistance through the formula ; δ is the friction coefficient between the pile and the soil; r f is the horizontal projection distance from the center of the strain gauge 11 to the rotation axis 31; the rotation axis 31 is the bottom surface axis of the barrel 301 of the double-well suction pile model 3, and the rotation axis is perpendicular to the lateral load. Referring to j as shown, when the double-well suction pile model 3 reaches the ultimate anti-overturning moment under the lateral load, the double-well suction pile model 3 rotates around the rotation axis 31. Figure 8 as shown, when the double-well suction pile model 3 reaches the ultimate anti-overturning moment under the lateral load, the double-well suction pile model 3 rotates around the rotation axis 31.

[0080] S4.3. Calculate the anti-overturning moment M provided by the ultimate bearing capacity of the foundation through the formula ; p b is the recorded data of the earth pressure cell 12; l2 is the average length of the embedding range of the earth pressure cell 12; l2 is the average width of the embedding range of the earth pressure cell 12; r i is the horizontal projection distance from the center of the earth pressure cell 12 to the rotation axis; i is the earth pressure cell 12 number, i = 1, 2... n. i is the horizontal projection distance from the center of the earth pressure cell 12 to the rotation axis; i is the earth pressure cell 12 number, i = 1, 2... n.

[0081] S4.4. Through the formula M R= M Ep + M f + M b ; Calculate the ultimate anti-overturning moment M of the double-well suction pile R .

[0082] In the above method, first drive the double-well suction pile model 3 to an inclination angle greater than 1° for overturning to ensure that the double-well suction pile model 3 overturns, and then obtain the moment when the double-well suction pile model 3 overturns; furthermore, the anti-overturning safety factor of the double-well suction pile model 3 in the overturned state can be obtained to judge whether the double-well suction pile model 3 will overturn when subjected to a lateral load; thus, the anti-overturning ability of the double-well suction pile can be tested.

[0083] In the calculation method of the ultimate anti-overturning moment of the double-well suction pile model 3, the double-well suction pile model 3 and the experimental soil layer 2 are regarded as an integral moving object; when the lateral load on the double-well suction pile model 3 reaches the limit, the cylinder 301 of the double-well suction pile model 3 rotates around the rotation axis; therefore, the ultimate anti-overturning moment of the double-well suction pile is determined by the anti-overturning moment provided by the passive earth pressure, the anti-overturning moment provided by the frictional resistance, and the anti-overturning moment provided by the ultimate bearing capacity of the foundation on the double-well suction pile model 3.

[0084] At the same time, the strain gauge 11 is used to detect the pressure on the circumferential side of the double-well suction pile model 3, and the anti-overturning moment provided by the passive earth pressure and the anti-overturning moment provided by the frictional resistance are calculated through the data of the strain gauge 11; the earth pressure cell 12 is used to detect the pressure acting on the experimental soil layer 2 in the vertical direction when the double-well suction pile model 3 tilts, and the anti-overturning moment provided by the ultimate bearing capacity of the foundation is calculated through the earth pressure cell 12; the method is simple.

[0085] In this specification, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0086] In the description of this specification, the description with reference to terms such as "preferred embodiment", "another embodiment", "other embodiments" or "specific examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0087] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. Double wellhead suction pile lateral stability test system, characterized by: It includes an experimental pool, a double wellhead suction pile model, a hydraulic thruster, a pressure sensor, an inclination sensor, a strain gauge, an earth pressure box and a data acquisition instrument; the pressure sensor, the inclination sensor, the strain gauge and the earth pressure box are all connected to the data acquisition instrument signal; The experimental pool is filled with an experimental soil layer, and the soil pressure box is evenly buried in the experimental soil layer, and the buried area of ​​the soil pressure box is larger than the cross-sectional area of ​​the double-wellhead suction pile model; the double-wellhead suction pile model is arranged in the experimental soil layer and is located above the soil pressure box, and the soil pressure box is used to detect the pressure acting on the experimental soil layer in the vertical direction when the double-wellhead suction pile model tilts; The hydraulic thruster is fixed on the side wall of the experimental pool and is located above the experimental soil layer. The output end of the hydraulic thruster is horizontally connected to the double-wellhead suction pile model. The pressure sensor is arranged at the output end of the hydraulic thruster. The pressure sensor is used to detect the pressure of the hydraulic thruster on the double-wellhead suction pile model. The inclination sensor is arranged on the double wellhead suction pile model, and is used to detect the inclination change of the double wellhead suction pile model; the strain gauge is evenly distributed on the side wall of the suction pile model, and is used to detect the pressure around the double wellhead suction pile model.

2. The double wellhead suction pile lateral stability test system according to claim 1 is characterized by: It also includes a force transmission rod and a force transmission sleeve, wherein the force transmission sleeve is fixed on the top of the double wellhead suction pile model; one end of the force transmission rod is connected to the force transmission sleeve, and the other end of the force transmission rod is connected to the output end of the hydraulic thruster.

3. The double wellhead suction pile lateral stability test system according to claim 2 is characterized by: The double wellhead suction pile model includes a cylinder and a top cover, wherein the top cover is arranged on the top of the cylinder; two inner conduits are arranged in the cylinder, the two inner conduits are symmetrically arranged about the axis of the cylinder, and the axis of the two inner conduits is arranged parallel to the axis of the cylinder; the bottom surface of the inner conduit is flush with the bottom surface of the cylinder, and the horizontal height of the top end of the inner conduit is located above the top cover.

4. The double wellhead suction pile lateral stability test system according to claim 3 is characterized by: The force transmission sleeve includes a force hole, a ball joint and a sleeve body; the force hole is arranged on one side of the sleeve body, and the force hole is connected to the sleeve body through the ball joint; the sleeve body is arranged at the top end of the inner guide tube; the force hole is at the same horizontal height as the output end of the hydraulic thruster, and the force transmission rod connects the force hole and the output end of the hydraulic thruster.

5. The double wellhead suction pile lateral stability test system according to claim 1 is characterized by: The thickness of the experimental soil layer is greater than the height of the double-wellhead suction pile model, and the thickness of the experimental soil layer is less than the depth of the experimental pool.

6. Double wellhead suction pile anti-overturning test method, characterized by: The double wellhead suction pile lateral stability test system is implemented as described in any one of claims 1 to 5, and the double wellhead suction pile anti-overturning test method comprises the following steps: S1, pre-installed earth pressure cell, strain gauge and inclination sensor; S2, placing a double wellhead suction pile model, installing a force transmission sleeve, and connecting the force transmission sleeve and the output end of the hydraulic thruster through a force transmission rod; S3, control the hydraulic thruster to move forward laterally, and the inclination sensor and the pressure sensor monitor and record the inclination and pressure of the double wellhead suction pile model in real time; until the inclination of the double wellhead suction pile model changes by more than 1°, then proceed to S4; S4. Obtain the ultimate anti-overturning moment M of the double wellhead suction pile model R ; S5, through η = M R / M O ; Calculate the anti-overturning safety factor η of the double wellhead suction pile model; M O is the overturning moment caused by the lateral load on the double wellhead suction pile model; S6. Determine whether the current anti-overturning safety factor of the double-wellhead suction pile model is greater than or equal to the preset safety factor; if so, determine that the double-wellhead suction pile model will not overturn when subjected to a lateral load; if not, determine that the double-wellhead suction pile model will overturn when subjected to a lateral load.

7. The method for testing the anti-tilt moment of a double wellhead suction pile according to claim 6, characterized in that: S4 specifically includes the following steps: S4.

1. By formula Calculate the anti-overturning moment M provided by the passive earth pressure Ep ; ε j is the recorded data of the strain gauge; E is the elastic modulus of the cylinder wall of the double wellhead suction pile model; l1 is the average length of the strain gauge pasting range; h1 is the average width of the strain gauge pasting range; d j is the vertical distance between the center of the strain gauge and the bottom surface of the double wellhead suction pile model; j is the strain gauge number, j = 1, 2...m; S4.2, by formula Calculate the anti-overturning moment M provided by friction resistance f ;δ is the friction coefficient of pile-soil interaction; r j is the horizontal projection distance from the center of the strain gauge to the rotation axis; the rotation axis is the axis of the bottom surface of the cylinder of the double wellhead suction pile model, and the rotation axis is perpendicular to the lateral load; S4.

3. By formula Calculate the anti-overturning moment M provided by the ultimate bearing capacity of the foundation b ;p i is the recorded data of the earth pressure box; l2 is the average length of the buried range of the earth pressure box; h2 is the average width of the buried range of the earth pressure box; r i is the horizontal projection distance from the center of the earth pressure box to the rotation axis; i is the number of the earth pressure box, i = 1, 2...n; S4.4, by formula M R =M Ep +M f +M b ; Calculate the ultimate anti-overturning moment M of the double wellhead suction pile R .

8. The double wellhead suction pile anti-overturning test method according to claim 6 is characterized by: S1 specifically includes the following steps: S1.

1. Bury several soil pressure boxes in the experimental soil layer. The soil pressure boxes are evenly distributed. Record the number and corresponding position of each soil pressure box. Each soil pressure box is connected to the data acquisition instrument signal. S1.

2. Evenly stick strain gauges on the outer side of the double wellhead suction pile model cylinder wall, record the number and position of each strain gauge, and connect each strain gauge to the data acquisition instrument signal; S1.

3. Install an inclination sensor at the axis center of the top of the double wellhead suction pile model, and connect the inclination sensor to the data acquisition instrument signal.

9. The double wellhead suction pile anti-overturning test method according to claim 6, characterized in that: S2 specifically includes the following steps: S2.1, vertically place the double wellhead suction pile model into the experimental soil layer, so that the inner guide tube axis of the double wellhead suction pile model and the axis of the output end of the hydraulic thruster are in the same plane; after the double wellhead suction pile model is placed, obtain the data of the inclination sensor; if the current inclination angle of the double wellhead suction pile model is not zero, re-place the double wellhead suction pile model; if the current inclination angle of the double wellhead suction pile model is zero, proceed to S2.3; S2.

3. Install the force transmission sleeve at the top of the inner guide tube close to the hydraulic thruster, with the force-bearing hole facing the hydraulic thruster and the axis of the force-bearing hole being on the same horizontal line as the axis of the output end of the hydraulic thruster.

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