Method for measuring force of pier in floating of large floating body considering bias coefficient

Abstract

The application discloses a method for measuring the force of a pier in the floating transportation of a large floating body by considering a bias coefficient, establishes a numerical model of the pier, introduces a bias coefficient of the pier through a heading front rubber pad compression amount and a heading back rubber pad compression amount, analyzes the force of the numerical model of the pier, selects a stress characteristic point on the front of the heading of the pier, and installs a stress sensor at the stress characteristic point; then, a relationship formula between normalized stress at the stress characteristic point and the bias coefficient is established, and a relationship formula between the pressure of the pier and the stress at the stress characteristic point and the bias coefficient is established; finally, stress data of the pier in the actual process of the floating transportation of the large floating body are collected through the bias coefficient and the stress sensor, and the pressure of the pier can be obtained by back calculation according to the established calculation formula.

Description

Technical Field

[0001] This invention belongs to the field of marine or waterborne floating connection stress monitoring technology, and in particular relates to a method for measuring the stress on the support piers during the floating of large floating bodies, taking into account the bias pressure coefficient. Background Technology

[0002] Large immersed tunnel sections are floated using either a single-hull or catamaran vessel. The hull and the immersed tunnel section are connected by supports and cables, forming a large floating structure. This structure offers excellent motion synchronization, significantly reducing the risks associated with drastic changes in sway and heave during the floating process. The forces acting on the hull-tunnel connection include support pressure, cable tension, and siding tension. Support pressure is the core force, directly impacting the success of the floating. Generally, the support pressure is high during floating, and the contact space between the support and the tunnel is small, making it difficult to deploy contact-type weighing sensors with the required range. Therefore, indirect methods are often used to measure the support pressure. Currently, most indirect measurement methods are based on the assumption of constant contact between the support and the tunnel, resulting in significant deviations between the measured support pressure and the actual pressure. This can easily lead to incorrect judgments in construction decisions during the floating of large floating structures.

[0003] The main reasons for the large errors in the above measurement methods are as follows: ① To reduce the impact force of the supports on the floats and the concentrated stress in the contact area between the supports and the floats during floating, rubber plates are installed under the supports as buffers. When connecting the floats, the cable force at both ends of the hull must first be applied to make the bow and stern supports contact the floats; then water is injected into the hull tanks to make all supports contact the floats. During this process, due to the deformation of the hull, the contact between the bottom of the supports and the floats is uneven, with greater rubber compression on one side of the supports along the bow and stern direction and less rubber compression on the other side. ② During floating, the connected floats are subjected to wind and wave forces and temperature differences, causing the increase in the tilt angle at the midship position to be significantly greater than that at the bow and stern positions, resulting in a gradual upward arching of the midships, which exacerbates the uneven stress on the supports. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for measuring the force on the support piers during the floating of large floating bodies, taking into account the bias coefficient.

[0005] This invention is achieved through the following technical solution:

[0006] A method for measuring the stress on the supports during the floating of a large floating body, considering the bias coefficient, includes the following steps:

[0007] Step 1: Establish a numerical model of the pier, including the front and back sides, two sides, bottom, top, and rubber pad. Define the pressure on the bottom surface of the pier, the bias coefficient, the compression of the rubber pad on the front side, the compression of the rubber pad on the back side, and the top of the pier as a fixed end constraint.

[0008] Step 2: Introduce the bearing bias coefficient by the compression amount of the rubber pad on the front of the heading and the compression amount of the rubber pad on the back of the heading;

[0009] Step 3: Perform stress analysis on the numerical model of the support pier constructed in Step 1, select stress characteristic points on the front of the support pier facing the direction of flight, and install stress sensors at the stress characteristic point locations.

[0010] Step 4: Establish the formula relating the normalized stress to the bias coefficient at the stress characteristic point;

[0011] Step 5: Establish the formula relating the pressure on the support pier to the stress and the eccentricity coefficient at the stress characteristic point.

[0012] Step 6: Collect stress data on the support piers during the actual floating process of the large floating body using bias coefficient and stress sensor. The support pier pressure can be obtained by back-calculation based on the calculation formula established in Step 5.

[0013] In the above technical solution, in step 2, it is assumed that: ① the load on the support is linearly distributed along the bow and stern of the ship and uniformly distributed along the left and right sides of the ship; ② the rubber at the bottom of the support is a homogeneous material, that is, the force on the support is proportional to the compression of the rubber plate.

[0014] The pressure calculation of the support piers satisfies the following formula:

[0015] ∫∫f(p)dpds=p0s0

[0016] In the formula: p is the load at the bottom of the pier, kPa; s is the area of ​​the rubber plate at the bottom of the pier, m². 2 p0 is the equivalent uniformly distributed load at the bottom of the pier, in kPa; s0 is the equivalent area of ​​the rubber plate at the bottom of the pier, in m². 2 ;

[0017] The load f(p) at the bottom of the pier is related to the load in the bow and stern directions, and the relationship is linear. To determine the load at the bottom of the pier during model calculation, an eccentricity coefficient k is introduced, which satisfies the following formula:

[0018]

[0019] Where: k is the bias coefficient; p1 is the boundary load of the rubber plate at the bottom of the support pier on the front side of the course, kPa; p2 is the boundary load of the rubber plate at the bottom of the support pier on the back side of the course, kPa; l1 is the compression of the rubber pad on the front side of the course, m; l2 is the compression of the rubber pad on the back side of the course, m.

[0020] In the above technical solution, in step 3, the stress characteristic point is preferably located on the central axis of the pier's frontal direction, at a distance of 1.0m from the bottom.

[0021] In the above technical solution, step 4 establishes the formula for the relationship between the normalized stress and the bias coefficient at the stress characteristic point as follows:

[0022]

[0023] In the formula: σ is the stress at the characteristic point of the pier, MPa; σ0 is the stress at the characteristic point of the pier under the action of the equivalent load p0, MPa.

[0024] In the above technical solution, in step five, numerical analysis is used to calculate the equivalent load at the bottom of the pier and the stress data at the characteristic point of the pier under uniformly distributed loads of different magnitudes. The relationship between the equivalent load p0 at the bottom of the pier and the stress σ0 at the stress characteristic point of the pier under the equivalent load is obtained by fitting these data. Then, based on the relationship between the pier pressure and the equivalent load and the relationship between the normalized stress and the bias coefficient at the stress characteristic point established in step 4, the relationship between the pier pressure and the stress and the bias coefficient at the stress characteristic point can be obtained.

[0025] In the above technical solution, the relationship between the pier pressure and the stress and eccentricity coefficient at the stress characteristic point obtained in step five is as follows:

[0026]

[0027] The advantages and beneficial effects of this invention are as follows:

[0028] This invention provides a method for measuring the pressure of a support under uneven stress. Compared with the existing technology, the measurement results have smaller errors. Furthermore, the current testing technology requires the selection of 2-4 stress characteristic points to install stress sensors, while this invention only requires the selection of 1 stress characteristic point to install stress sensor. The testing method is simple and economical. Attached Figure Description

[0029] Figure 1 This is a numerical model diagram of the pier established in this invention.

[0030] Figure 2 This is the force cloud diagram of the support when the pressure on the support is 4000kN and the bias coefficient is 3 in this invention.

[0031] Figure 3 When the support pressure is 4000kN, the eccentricity coefficient is 0. 1, 3, 7, 10, 20, +∞, Distribution of compressive stress magnitude along the stress characteristic line path of the support pier.

[0032] Figure 4 When the distributed pressure on the abutment is 2000kN, 4000kN, 6000kN, 8000kN, 10000kN, and 12000kN, the bias coefficient is 0. For 1, 3, 7, 10, and 20, perform orthogonal combination analysis to obtain the relationship between stress and eccentricity coefficient at the stress characteristic points of the support pier.

[0033] Figure 5 It is a normalized diagram showing the relationship between stress and bias coefficient at the stress characteristic point of the pier support.

[0034] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below with reference to specific embodiments.

[0036] A method for measuring the stress on the supports during the floating of a large floating body, considering the bias coefficient, includes the following steps:

[0037] Step 1: Establish a numerical model of the support pier, including the front (1), back (2), two sides (2), bottom (3), top (4), and rubber pad (5). Define the pressure on the bottom surface of the support pier, the bias coefficient, the compression of the rubber pad on the front (2), the compression of the rubber pad on the back (2), and the top of the support pier as a fixed end constraint.

[0038] Step Two: Propose the assumptions for the pier pressure calculation model, and introduce the pier bias coefficient based on the compression amounts of the rubber pads on the front and back of the course. The specific implementation is as follows:

[0039] The following assumptions are made: ① The load on the support is linearly distributed along the bow and stern of the ship and uniformly distributed along the left and right sides of the ship; ② The rubber at the bottom of the support is a homogeneous material, that is, the force on the support is directly proportional to the compression of the rubber plate.

[0040] The pressure calculation of the support pier satisfies the following formula:

[0041] ∫∫f(p)dpds=p0s0 (1)

[0042] In the formula: p is the load at the bottom of the pier, kPa; s is the area of ​​the rubber plate at the bottom of the pier, m². 2 p0 is the equivalent uniformly distributed load at the bottom of the pier, in kPa; s0 is the equivalent area of ​​the rubber plate at the bottom of the pier, in m². 2 .

[0043] The load f(p) at the bottom of the pier is related to the load in the bow and stern directions and the relationship is linear. To determine the load at the bottom of the pier during model calculation, an eccentricity coefficient k is introduced, which satisfies the following formula.

[0044]

[0045] Where: k is the bias coefficient; p1 is the boundary load of the rubber plate at the bottom of the support pier on the front side of the course, kPa; p2 is the boundary load of the rubber plate at the bottom of the support pier on the back side of the course, kPa; l1 is the compression of the rubber pad on the front side of the course, m; l2 is the compression of the rubber pad on the back side of the course, m.

[0046] Step 3: Perform stress analysis on the numerical model of the pier constructed in Step 1. Select stress characteristic points on the front of the pier facing the direction of travel, and install stress sensors at these points. The specific implementation is as follows:

[0047] When the pressure on the pier is 4000kN and k=3, the force contour diagram of the pier is as follows: Figure 2 As shown, the stress distribution along the centerline of the pier's frontal face is relatively uniform; therefore, the centerline of the frontal face is selected as the stress characteristic line. When the pier pressure is 4000 kN, numerical analysis is used to plot the eccentricity coefficient k as 0. 1, 3, 7, 10, 20, +∞, the pressure distribution curves on the stress characteristic lines of the pier, such as Figure 3 As shown. Figure 3 Point 0 represents the intersection of the stress characteristic line and the bottom of the pier. Figure 3 It can be seen that the stress is relatively large and uniform at a distance of 1.0m from the bottom. Therefore, the stress characteristic point (monitoring point) is located at a distance of 1.0m from the bottom on the stress characteristic line on the front of the support pier along the flight direction.

[0048] Step 4: Establish the formula relating the normalized stress to the bias coefficient at the stress characteristic point. The specific implementation is as follows:

[0049] For the bearing pressure F = 2000kN, 4000kN, 6000kN, 8000kN, 10000kN, and 12000kN, the bias coefficient k = 0. For models 1, 3, 7, 10, and 20, perform orthogonal combination design, calculate 60 sets of numerical models, and plot the relationship curves between characteristic point stress and bias coefficient, such as... Figure 4 As shown. According to Figure 4 The stress at the characteristic points of the pier is normalized, and the relationship curve between the normalized stress and the bias coefficient is plotted, such as... Figure 5 As shown. The normalized stress and bias coefficient are fitted, and the fitting formula is shown in formula (3). The coefficient of determination R in formula (3) is... 2 =99.6%. This indicates that the fitting formula is accurate.

[0050]

[0051] In the formula: σ is the stress at the characteristic point of the pier, MPa; σ0 is the stress at the characteristic point of the pier under the action of the equivalent load p0, MPa.

[0052] Step 5: Establish the relationship between the pressure on the support pier and the stress and eccentricity coefficient at the stress characteristic point. The specific implementation is as follows:

[0053] Numerical analysis was used to calculate the equivalent load at the bottom of the pier and the stress at the characteristic points of the pier under uniformly distributed loads of 2000kN, 4000kN, 6000kN, 8000kN, 10000kN, and 12000kN. The calculation results are as follows:

[0054] Table 1: Stress results at characteristic points of the pier under uniformly distributed load.

[0055]

[0056]

[0057] Formula (4) is obtained by fitting the data in Table 1.

[0058] p0 = 118.66σ0 - 54.93 (4)

[0059] The following relationship exists between the bearing pressure and the equivalent load:

[0060] F = p0s0 (5)

[0061] Substituting formulas (3) and (4) into formula (5) yields the formula for calculating the pressure on the pier.

[0062]

[0063] Step Six: Collect stress data on the support piers during the actual floating process of the large floating body using bias coefficient and stress sensors. The support pier pressure can be obtained by back-calculation based on the calculation formula established in Step Five.

[0064] The pier pressure was calculated using both the existing pier pressure testing method (which does not consider the bias coefficient) and the pier pressure testing method of this invention, under two conditions: Condition 1 (cable preload of 12170 kN) and Condition 2 (immersion tube buoyancy of 12000 kN and cable preload of 8970 kN). The calculation results are as follows:

[0065] Table 2: Comparison of existing pier pressure testing methods without considering the bias coefficient and the pier pressure testing method of this invention.

[0066]

[0067]

[0068] Under various working conditions, the resultant force of the support pressure obtained by the current support pressure test method that does not consider the bias coefficient deviates from the true value of the support pressure by about 30%, while the resultant force of the support pressure obtained by the test method of the present invention deviates from the true value of the support pressure by less than 5%.

[0069] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for measuring the force on the support piers during the floating and transport of a large floating body, considering the bias coefficient, characterized in that, Includes the following steps: Step 1: Establish a numerical model of the pier, including the front and back sides, two sides, bottom, top, and rubber pad. Define the pressure on the bottom surface of the pier, the bias coefficient, the compression of the rubber pad on the front side, the compression of the rubber pad on the back side, and the top of the pier as a fixed end constraint. Step 2: Introduce the bearing bias coefficient by the compression amount of the rubber pad on the front of the heading and the compression amount of the rubber pad on the back of the heading; Step 3: Perform stress analysis on the numerical model of the support pier constructed in Step 1, select stress characteristic points on the front of the support pier facing the direction of flight, and install stress sensors at the stress characteristic point locations. Step 4: Establish the formula relating the normalized stress to the bias coefficient at the stress characteristic point; Step 5: Establish the formula relating the pressure on the support pier to the stress and the eccentricity coefficient at the stress characteristic point. Step 6: Collect stress data on the support piers during the actual floating process of the large floating body using bias coefficient and stress sensor. The support pier pressure can be obtained by back-calculation based on the calculation formula established in Step 5.

2. The method for measuring the force on the support piers during the floating and transport of large floating bodies, considering the bias coefficient, as described in claim 1, is characterized in that: In step 2, it is assumed that: ① the load on the support is linearly distributed along the bow and stern of the ship and uniformly distributed along the left and right sides of the ship; ② the rubber at the bottom of the support is a homogeneous material, that is, the force on the support is proportional to the compression of the rubber plate. The pressure calculation of the support piers satisfies the following formula: ∫∫f(p)dpds=p0s0 In the formula: p is the load at the bottom of the pier, kPa; s is the area of ​​the rubber plate at the bottom of the pier, m². 2 ; p0 is the equivalent uniformly distributed load at the bottom of the pier, in kPa; s0 is the equivalent area of ​​the rubber plate at the bottom of the pier, in m². 2 ; The load f(p) at the bottom of the pier is related to the load in the bow and stern directions, and the relationship is linear. To determine the load at the bottom of the pier during model calculation, an eccentricity coefficient k is introduced, which satisfies the following formula: Where: k is the bias coefficient; p1 is the boundary load of the rubber plate at the bottom of the support pier on the front side of the course, kPa; p2 is the boundary load of the rubber plate at the bottom of the support pier on the back side of the course, kPa; l1 is the compression of the rubber pad on the front side of the course, m; l2 is the compression of the rubber pad on the back side of the course, m.

3. The method for measuring the support force during the floating and transport of large floating bodies, considering the bias coefficient, as described in claim 1, is characterized in that: In step 3, the stress characteristic point is located 1.0m from the bottom on the centerline of the front of the pier along the flight direction.

4. The method for measuring the support force during the floating and transport of large floating bodies, considering the bias coefficient, as described in claim 1, is characterized in that: In step 4, the formula for establishing the relationship between the normalized stress and the bias coefficient at the stress characteristic point is as follows: In the formula: σ is the stress at the characteristic point of the pier, MPa; σ0 is the stress at the characteristic point of the pier under the action of the equivalent load p0, MPa.

5. The method for measuring the force on the support piers during the floating and transport of large floating bodies, considering the bias coefficient, as described in claim 1, is characterized in that: In step five, numerical analysis is used to calculate the equivalent load at the bottom of the pier and the stress data at the characteristic point of the pier under uniformly distributed loads of different magnitudes. The relationship between the equivalent load p0 at the bottom of the pier and the stress σ0 at the stress characteristic point of the pier under the equivalent load is obtained by fitting these data. Then, based on the relationship between the pier pressure and the equivalent load and the relationship between the normalized stress and the bias coefficient at the stress characteristic point established in step four, the relationship between the pier pressure and the stress and the bias coefficient at the stress characteristic point can be obtained.

6. The method for measuring the force on the support piers during the floating and transport of large floating bodies, considering the bias coefficient, as described in claim 1, is characterized in that: In step five, the formulas relating the pier pressure to the stress and the eccentricity coefficient at the stress characteristic point are as follows:

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