Air pressure balancing construction method for asymmetric bucket type foundation

Abstract

The invention discloses an air pressure balancing method for an asymmetric bucket type foundation, which comprises the following steps of: dividing a bin control area, namely dividing a bin into i groups of control areas; calculating parameters are determined, and computer aided design software is adopted to obtain data and process the data; calculating the air pressure state in the barrel at the foundation floating moment, and calculating the air pressure in the barrel according to the communicating vessel principle; the fixed inclination height of the bucket foundation at the floating moment is calculated, the initial buoyancy center position is determined, and the fixed inclination height is calculated; and a basic staged diving scheme is determined, and the staged diving scheme is determined according to the exhaust diving height corresponding to each control area. According to the method, zone control is conducted on the gas state of each cabin in the barrel in the diving stage of the barrel type foundation, balancing is achieved through zone control over the gas pressure in the barrel, the overwater operation time is shortened, the influence on the construction period is reduced, and the floating stability in the floating stage of the barrel type foundation is improved.

Description

Technical Field

[0001] This invention relates to the field of marine engineering, and more particularly to a pneumatic balancing construction method for asymmetric barrel foundations. Background Technology

[0002] Precast concrete bucket foundations (hereinafter referred to as bucket foundations) are a new type of waterway engineering structure with an open bottom and a closed top. The foundation structure is precast on land and installed on water, offering advantages such as guaranteed precast quality, fast installation speed on water, minimal impact on the marine environment, and environmental friendliness. Waterway engineering structures, represented by wharves and breakwaters, are characterized by long structural axes and a large number of foundations. They typically adopt a variable cross-section structure with a smaller upper cylinder and a larger lower cylinder. The lower cylinder is buried in the soil to ensure the foundation's bearing capacity and stability, while the upper cylinder is exposed to the water to meet structural requirements. The upper and lower cylinders are integrated, and a toe plate is added to the end of the upper cylinder to enhance its ability to resist lateral loads. A typical variable cross-section bucket foundation includes an upper cylinder and a lower cylinder; the lower cylinder can be further divided into a lower cylinder top cover, an outer wall, and an inner partition wall, while the upper cylinder can be divided into an upper cylinder toe plate, an outer wall, and an inner partition wall.

[0003] The planar dimensions of the barrel foundation can reach 40m × 20m, the height can reach (14m for the lower barrel + 20m for the upper barrel), and the weight can reach 5500t. The main construction steps include: prefabrication of the barrel foundation structure, lowering the barrel foundation onto a barge, transporting it to the submersible pit by a semi-submersible barge, submerging the semi-submersible barge—air-floating the barrel foundation, air-floating displacement of the barrel foundation, positioning, venting and sinking, and pumping and sinking. Among these, air-floating displacement and venting and drainage sinking are unique processes that utilize the structural characteristics of the barrel foundation. Air flotation positioning technology fully utilizes the structural characteristics of barrel foundations. It achieves stable floating by compressing the gas sealed inside the barrel, requiring only a semi-submersible barge and eliminating the need for a large crane vessel. The principle involves controlled, phased submersion, allowing external water to enter the bottom of the barrel to form a sealing layer, compressing the gas inside, and ultimately balancing the buoyancy and gravity of the barrel foundation, achieving buoyancy. By controlling the height of the center of buoyancy, when the barrel foundation experiences slight swaying under environmental loads, the resultant torque of gravity and buoyancy becomes the restoring torque that returns the foundation to its equilibrium position. Key indicators during the air flotation process of barrel foundations include: freeboard height, foundation draft, sealing layer thickness, and the difference between the internal and external liquid levels. Air venting and sinking utilize the self-weight of the barrel foundation to expel the gas inside, causing the foundation to sink. Pumping and sinking utilizes pumping water to reduce the pressure inside the barrel, creating a pressure difference between the inside and outside, thereby overcoming resistance and achieving sinking. Compared to caisson foundations, no foundation treatment is required; compared to pile foundations, no pile driving equipment is needed; and construction is noiseless.

[0004] Casket foundations were first used in breakwater engineering for water transport. A symmetrical structure (with the upper and lower cylinder axes coinciding) can withstand horizontal loads such as waves and currents. However, with the widespread application of bucket foundations to wharves, the significant lateral earth pressure caused by shore fill makes symmetrical structures unsuitable for the horizontal bearing capacity and deformation requirements of bucket foundations in specific foundation conditions such as deep soft soil. Therefore, some teams have proposed asymmetrical bucket foundations as a solution for wharves and shore-connecting structures. Positioning the upper cylinder off-shore increases the vertical pressure at the cylinder end under the same lateral earth pressure, thereby increasing the bucket foundation's anti-slip bearing capacity. However, using an asymmetrical bucket foundation negatively impacts its stability during air-floating displacement. Asymmetrical structures require balancing measures, the most common being counterweights. This introduces additional steps for counterweight installation and subsequent recovery. More importantly, balancing blocks are typically placed on the top of the lower cylinder, increasing the bucket foundation's center of gravity and thus deteriorating its floating stability—that is, increasing the difference between the foundation's center of gravity and buoyancy height, and decreasing the tilting height. Summary of the Invention

[0005] The purpose of this invention is to provide a pneumatic balancing construction method for asymmetric barrel foundations. Balancing is achieved by controlling the air pressure inside the barrel in zones, eliminating the need for additional counterweights, reducing the time spent on the water, and improving the floating stability of the barrel foundation during the buoyancy stage. This method can be implemented by adding steps to the conventional barrel foundation submersion scheme, with minimal impact on the construction period and no need to add ship machinery.

[0006] The technical solution to achieve the above objectives is:

[0007] A method for pneumatic balancing of an asymmetric barrel foundation includes:

[0008] Step S1: Divide the warehouse control area into i groups of control areas;

[0009] Step S2: Determine the calculation parameters, and use computer-aided design software to obtain and process the data;

[0010] Step S3: Calculate the air pressure inside the barrel at the moment of basic buoyancy by calculating the air pressure inside the barrel based on the principle of communicating vessels.

[0011] Step S4: Calculate the constant tilt height of the barrel foundation at the moment of buoyancy, determine the initial position of the center of buoyancy, and calculate the constant tilt height;

[0012] Step S5: Determine the basic phased diving plan. The phased diving plan is determined based on the exhaust diving height corresponding to each control zone.

[0013] Preferably, the control zones are at least two groups, and usually two groups are selected. The parameters of the compartments within the same control zone are the same, while the parameters of different control zones are different.

[0014] Preferably, in step S2, the parameters include: the total cross-sectional area of ​​each control area, the distance from the centroid of the total cross-section to the central axis of the lower bucket, the cavity area of ​​each compartment, and the distance from the centroid of the cavity of each compartment to the central axis of the lower bucket.

[0015] Preferably, after determining the parameters, data processing is performed, including:

[0016] Calculate the sum of the cavity areas of each compartment within each control area, A. hi The formula used is:

[0017]

[0018] Calculate the sum of the concrete cross-sectional areas A within each control area. ci The formula used is:

[0019] A ci =A si -A hi ;

[0020] Calculate the distance L from the centroid of the total concrete cross-sectional area in each control area to the central axis of the lower bucket. ci The formula used is:

[0021]

[0022] in, Let A be the cavity area of ​​the j-th compartment within the i-th control zone. si Let L be the total cross-sectional area of ​​the i-th control region. si m is the distance from the centroid of the entire cross-section of the i-th control region to the central axis of the lower bucket; i This represents the total number of compartments within control zone i.

[0023] Preferably, step S3 includes:

[0024] Step S31, input the known parameters;

[0025] Step S32, the liquid level difference Δh between inside and outside control zone 1. w1 Assignment;

[0026] Step S33, calculate the liquid level difference Δh inside and outside control zone 2 based on force balance. w2 ;

[0027] Step S34: Calculate the liquid level difference Δh inside and outside the control zone 2 based on torque balance. w2 ;

[0028] Step S35: Calculate the iteration error;

[0029] Step S36, iterative calculation: when the iterative error δ≥e, repeat steps S32-S35 until the error meets the requirements; e is the set allowable error range.

[0030] Step S37: Calculate the air pressure state inside the barrel.

[0031] Preferably, step S33 uses the following formula:

[0032] Δh w2 =[V0-h w ·(A c1 +A c2 )-Δh w1 ·A h1 ] / A h2

[0033] Where V0 is the basic drainage volume, h w For the draft of the bucket foundation, A c1 A is the sum of the cross-sectional areas of the concrete in the control zone 1. c2 A is the sum of the cross-sectional areas of the concrete in the control zone 2. h1 A is the sum of the cavity areas of all compartments within control area 1. h2 This is the sum of the cavity areas of all compartments within control zone 2;

[0034] Step S34 uses the following formula:

[0035] Δh w2 ′=[(Δh w1 ·A s1 ·L s1 +h sw1 ·A c1 ·L c1 )-h sw2 ·A c2 ·L c2 -Z0] / (A s2 ·L s2 )

[0036] h swi =h w -Δh wi

[0037] Among them, A s1 and A s2 L represents the total cross-sectional area of ​​the first and second control zones. s1 and L s2 h is the distance from the centroid of the entire cross-section of the first and second control areas to the central axis of the lower bucket. sw1 h sw2 and h swi L represents the bottom sealing water height in the 1st, 2nd, and i-th control zones.c1 and L c2 Z0 is the distance from the centroid of the total concrete cross-sectional area in the first and second control areas to the central axis of the lower bucket; Z0 is the drainage volume displacement corresponding to the asymmetric moment of the asymmetric bucket foundation structure itself; Δh wi The difference in liquid level between the inside and outside of control zone i;

[0038] Step S35 uses the formula δ=|Δh w2 -Δh w2 ′\ / Δh w2 δ is the iteration error;

[0039] Step S37 uses the formula: P ai =P a +Δh wi ·γ w P ai Let γ be the air pressure inside the barrel in the i-th control zone. w For the specific gravity of seawater, P a =101.325 kPa, which is the standard atmospheric pressure.

[0040] Preferably, in step S4, the initial buoyancy center position is calculated using the following formula:

[0041]

[0042] Y c The initial position of the center of buoyancy;

[0043] The constant tilt height is calculated using the following formula:

[0044]

[0045] a = Y G -Y C

[0046] Where m is the constant inclination height, ρ is the constant inclination diameter, V0 is the structural drainage volume, and Y... G Let 'a' be the location of the structure's center of gravity, 'a' be the distance from the center of gravity to the center of buoyancy, 'I' be the moment of inertia of the structure's cross-section at the water surface regarding its longitudinal and transverse central axes, and 'i' be the distance from the center of gravity to the center of buoyancy. j Let n be the moment of inertia of the ballast water surface in the j-th compartment on the longitudinal and transverse central axes of that water surface, and n be the total number of compartments. l This represents the total number of compartments perpendicular to the calculation axis.

[0047] Preferably, in step S5, the exhaust submersion height corresponding to each control zone is calculated using the following formula:

[0048] h di =Hh p -P ai / P a·(Δh wi +h0-h p )

[0049] Among them, h di H is the exhaust submersion height of the i-th control zone, H is the bottom height of the bucket foundation, and h is the bottom height of the bucket. p h0 is the thickness of the top cover plate of the barrel foundation, and h0 is the freeboard height.

[0050] Preferably, in step S5, if the number of control zones is 2, the phased diving scheme can be divided into three types:

[0051] 0≤h d1 <h d2 It is divided into 3 stages;

[0052] h d1 <0≤h d2 It is divided into 4 stages;

[0053] h d1 <h d2 <0, divided into 3 stages;

[0054] h d1 The exhaust depth of control zone 1; h d2 The exhaust depth of control zone 2.

[0055] Preferably, each diving scheme changes the air pressure by adjusting the chamber exhaust valve and inflating the chamber, controlling the semi-submersible barge to descend to different drafts of the barrel foundation, ultimately controlling it to the draft h of the barrel foundation. w Asymmetric barrel foundation for floating.

[0056] The beneficial effects of this invention are as follows: This invention controls the gas state of each compartment in the barrel during the submersion stage of the barrel foundation by partitioning it, and achieves balancing by controlling the air pressure in the barrel by partitioning it. This eliminates the need for additional counterweights, reduces the time spent on the water, has little impact on the construction period, eliminates the need for additional ship machinery, improves the floating stability of the barrel foundation during the buoyancy stage, and provides a specific quantitative analysis method for the air pressure balancing process of asymmetric barrel foundations. Attached Figure Description

[0057] Figure 1 This is a flowchart of the pneumatic balancing construction method for the asymmetric barrel foundation of the present invention.

[0058] Figure 2 This is a diagram of the asymmetric barrel-type foundation structure in this invention;

[0059] Figure 3 This is a schematic diagram of the compartment control area division of the asymmetric barrel-shaped foundation structure in this invention;

[0060] Figure 4This is a schematic diagram of the cross-sectional characteristics of the control area compartment in this invention;

[0061] Figure 5 This is a cross-sectional parameter diagram of the asymmetric barrel foundation pneumatic balancing scheme in this invention;

[0062] Figure 6 This is a flowchart of the specific process for calculating the air pressure state inside the barrel at the basic buoyancy moment in step S3 of this invention.

[0063] Figure 7 This is a diagram showing the calculation results of the asymmetric barrel foundation air pressure balancing and buoyancy moment in this invention;

[0064] Figure 8 This is a diagram showing the calculation results of the air pressure balancing stability of the asymmetric barrel foundation in this invention;

[0065] Figure 9 This is a schematic diagram of the asymmetric barrel foundation air pressure balancing submersion scheme ① in this invention;

[0066] Figure 10 This is a schematic diagram of the asymmetric barrel foundation air pressure balancing submersion scheme ② in this invention;

[0067] Figure 11 This is a schematic diagram of the asymmetric barrel foundation air pressure balancing submersion scheme ③ in this invention;

[0068] Figure 12 This is a diagram illustrating the iterative calculation process of the asymmetric barrel foundation air pressure in this invention. Detailed Implementation

[0069] The invention will now be further described with reference to the accompanying drawings.

[0070] Please see Figure 1 The pneumatic balancing construction method for asymmetric bucket foundations of the present invention includes the following steps:

[0071] Basic information about asymmetric bucket foundations: A certain asymmetric bucket foundation structure is shown below. Figure 2As shown (dimensions are in mm), the barrel foundation is 26.5m high, the upper barrel is 12.5m high, and the lower barrel is 14.0m high. The upper barrel is 14.0m long and 20.0m wide, and the lower barrel is 40.0m long and 20.0m wide. The outer wall thickness of the upper barrel is 0.4m, and the inner partition wall thickness is 0.3m. The outer wall thickness of the lower barrel is 0.4m, and the inner partition wall thickness is 0.3m. The lower barrel is divided into 15 compartments, and the top cover of the lower barrel is 0.5m thick. The distance between the axis of symmetry of the upper barrel and the axis of symmetry of the lower barrel is 3.4m. The total weight of the barrel foundation itself is 5302.8t, the height of the center of gravity of the structure itself is 11.64m (the bottom of the lower barrel is the 0 point, the same below), the weight of the upper barrel is 1371.9t, and the eccentric moment is 4664.4t·m. The most unfavorable working condition in the air flotation transportation stage is along the short side (x), with the moment of inertia of the barrel foundation section Ix=21187.3m4, and the moment of inertia of the liquid surface of all compartments ∑ix=1915.2m4.

[0072] Step S1: Divide the control areas of the storage compartments. Based on the characteristics of the asymmetric barrel foundation structure, divide the storage compartments into i groups. Within the same control area, the air column height, air pressure, and bottom water thickness are the same. The parameters differ between different control areas to facilitate subsequent air pressure balancing. The minimum number of groups is 2 (i≥2), and the maximum number of groups can be the same as the number of storage compartments n (i≤n).

[0073] In this embodiment, the 15 compartments of the barrel foundation are divided into control area 1 and control area 2, as follows: Figure 3 As shown. By increasing the amount of gas in control zone 1, the buoyancy torque generated by the two control zones balances the unbalanced torque of the asymmetric structure itself.

[0074] Step S2: Determine the calculation parameters. Based on the division of the control zones within the storage compartments, use computer-aided design software to obtain the total cross-sectional area As1, As2…Asi of each control zone, and the distances Ls1, Ls2…Lsi from the centroid (Cs1, Cs2…Csi) of each control zone to the central axis of the lower bucket; and obtain the cavity area of ​​each compartment within each control zone. and the centroid of each compartment cavity Distance to the central axis of the lower bucket i represents the control area number, j represents the warehouse number within control area i, and m i This represents the total number of compartments within control zone i.

[0075] Then, data processing is performed:

[0076] Calculate the sum of the cavity areas A of each compartment within each control area. hi The formula used is:

[0077]

[0078] Calculate the sum of the concrete cross-sectional areas A within each control area. ci The formula used is:

[0079] A ci =A si -A hi ;

[0080] Calculate the distance L from the centroid of the total concrete cross-sectional area in each control area to the central axis of the lower bucket. ci The formula used is:

[0081]

[0082] Using computer-aided software for drawing, such as Figure 4 As shown, the interface characteristics within each control area are obtained, including information such as area and distance from the centroid to the central axis of the lower bucket. Figure 5 As shown.

[0083] Step S3: Calculate the air pressure inside the bucket at the initial buoyancy moment. The specific process is as follows: Figure 6 As shown.

[0084] Step S31: Calculate the foundation drainage volume V0 and the drainage volume distance Z0 corresponding to the asymmetric moment of the asymmetric barrel foundation structure itself based on the barrel foundation dimensions. Select the freeboard height h0 according to the operating environment. Determine the draft h of the barrel foundation based on the barrel foundation height and the freeboard height. w ;

[0085] Step S32, the liquid level difference Δh between inside and outside control zone 1. w1 Assignment;

[0086] Step S33: Calculate the difference in liquid level inside and outside the bucket within control zone 2 based on vertical force balance (the resultant force of the self-weight of the bucket foundation and the buoyancy of each control zone is equal in magnitude and opposite in direction):

[0087] Δh w2 =[V0-h w ·(A c1 +A c2 )-Δh w1 ·A h1 ] / A h2

[0088] Step S34, calculate the liquid level difference between the inside and outside of the bucket in control zone 2 based on torque balance (the eccentric torque of the bucket foundation structure and the resultant torque of the buoyancy in each control zone are equal in magnitude and opposite in direction):

[0089] Δh w2 ′=[(Δh w1 ·A s1 ·L s1 +h sw1 ·A c1 ·L c1 )-h sw2·A c2 ·L c2 -Z0] / (A s2 ·L s2 )

[0090] The bottom sealing water height h in each control zone swi =h w -Δh wi ,

[0091] Due to Δh w2 The calculation uses Δh obtained in step ③. w2 It requires iterative calculation.

[0092] Step S35, calculate the iteration error using the formula: δ=|Δh w2 -Δh w2 ′| / Δh w2 ;

[0093] Step S36, iterative calculation: When δ≥e, where e is the set allowable error range, repeat steps S32-S35 until the error meets the requirements, thus obtaining the thickness of the bottom sealing water and the difference between the inner and outer liquid levels at the moment the bucket foundation floats.

[0094] Step S37, Calculate the air pressure inside the barrel: Calculate the moment the barrel foundation rises and the air pressure inside the barrel in each control zone based on the principle of communicating vessels.

[0095] P ai =P a +Δh wi ·γ w

[0096] Where γ w The specific weight of seawater is Pa = 101.325 kPa, which is the standard atmospheric pressure.

[0097] Assuming a freeboard height of 1.1m, the difference between the inner and outer liquid levels in control zones 1 and 2 at the moment of buoyancy of the barrel foundation is calculated using force balance and moment balance equations, respectively. Trial calculations are then used to determine the result that meets the error requirements. Figure 7 As shown.

[0098] Step S4: Calculate the tilt height of the barrel foundation at the moment of buoyancy. The main difference between the asymmetric barrel foundation with pneumatic balancing and the conventional balancing process lies in the calculation of the initial buoyancy center position YC. Since the bottom water height varies in different control zones, the overall buoyancy center height needs to be determined by the buoyancy torque and buoyancy generated in each control zone compartment.

[0099]

[0100] After confirming Y cThe tilt height can be calculated using the following formula, referring to the standard barrel foundation:

[0101]

[0102] a = Y G -Y C

[0103] Where m is the constant inclination height (m), ρ is the constant inclination diameter (m), and V0 is the structural drainage volume (m³). 3 ), Y G Let be the location of the structure's center of gravity, 'a' be the distance from the center of gravity to the center of buoyancy (m), 'I' be the moment of inertia of the structure's cross-section at the water surface about the longitudinal (transverse) central axis (m⁴), and 'i' be the position of the structure's center of gravity. j Let n be the moment of inertia (m⁴) of the ballast water surface in the j-th compartment on the longitudinal (transverse) central axis of that water surface, and n be the total number of compartments. l This represents the total number of compartments perpendicular to the calculation axis.

[0104] Figure 8 The stability calculation of the barrel foundation based on the gas state in control zone 1 and control zone 2 is shown. The constant tilt height = 0.684m > 0.6m, which meets the specification requirements. This indicates that under the same freeboard height, the pneumatic trimming process can improve the floating stability of the foundation compared with the conventional trimming block trimming process. The reason is that the pneumatic trimming does not raise the center of gravity of the foundation.

[0105] Step S5: Determine the phased descent plan.

[0106] Calculate the exhaust submersion height of each control zone, i.e., the submersion depth when the air valve is open and the gas inside and outside the tank is connected:

[0107] h di =Hh p -P ai / P a ·(Δh wi +h0-h p )

[0108] Where H is the height of the bottom bucket of the bucket foundation, h p The thickness of the top cover plate of the barrel under the barrel foundation.

[0109] The phased diving plan is determined based on the relative relationship between the exhaust diving height results corresponding to each control zone.

[0110] Taking a control zone with n=2 as an example, assuming that control zone 1 is located on the asymmetrically weighted side of the barrel foundation, the air pressure in control zone 1 should be greater than that in control zone 2, and the exhaust depth h of control zone 1 should be greater. d1 The exhaust depth h should be less than the control zone 2. d2 .

[0111] ①0≤hd1 <h d2

[0112] The descent is divided into three stages, such as Figure 9 As shown:

[0113] Phase 1: Open all compartment exhaust valves and control the semi-submersible barge to descend to the barrel foundation draft = h. d1 The descent was then immediately halted, and after the air pressure inside and outside the tank was balanced, all exhaust valves in control area 1 were closed.

[0114] Phase Two: Maintain all compartment exhaust valves closed in Control Zone 1 and all compartment exhaust valves open in Control Zone 2, and control the semi-submersible barge to submerge to the barrel foundation draft = h. d2 The descent was then immediately halted, and after the air pressure inside and outside the tank was balanced, all exhaust valves in control area 2 were closed.

[0115] Phase 3: Keep all compartment exhaust valves closed and control the semi-submersible barge to descend to the barrel foundation draft = h. w At this point, the asymmetric barrel foundation begins to float.

[0116] ②h d1 <0≤h d2

[0117] The descent is divided into four stages, such as Figure 10 As shown:

[0118] Phase 1: Maintain all vent valves in control area 1 closed and all vent valves in control area 2 open, and control the semi-submersible barge to submerge to the barrel foundation draft = h. d2 The descent was then immediately halted, and after the air pressure inside and outside the tank was balanced, all exhaust valves in control area 2 were closed.

[0119] Phase Two: Keep all compartment vent valves closed and control the semi-submersible barge to descend to the barrel foundation draft = h. d3 The dive was then immediately halted.

[0120] Phase 3: Synchronously inflate the compartments within control zone 1 until the air pressure reaches the preset value P. a1-hd3-c .

[0121] h d1 <0 indicates that even if the compartments within the controlled area are not vented at all, the gas volume is insufficient, so inflation is required to increase the gas volume. Inflation will reduce the bottom water depth. To avoid insufficient bottom water depth, the entire bucket foundation will be submerged to the draft h. d3 =(h d2 +h w) / 2, corresponding to the freeboard height h 0-d3 =Hh d3 .

[0122] First, using the ideal gas law and the principle of communicating vessels, the relationship between cabin pressure and diving depth under non-venting diving conditions is derived:

[0123] P a ·(Hh p ) = P a1 ·(Δh w1 +h0-h p )

[0124] P a1 =P a +Δh w1 ·γ w

[0125] By combining the above equations, a trial calculation was performed to determine the air pressure P in control area 1 when the dive reached a draft of hd3. a1-hd3-0 .

[0126] With basic draft = h d3 At that time, gas was synchronously injected into all compartments in control area 1. To simplify the analysis, the changes in basic draft and freeboard caused by gas injection were ignored in the theoretical analysis.

[0127] The height of the air column after inflation, determined by its operating principle, is as follows:

[0128] h a1-hd3-c ′=(P a1-hd3-c ′-P a ) / γ w +h 0-d3 -h p

[0129] From the ideal gas formulas for the two states of stable gas injection and floating, we can obtain:

[0130] h a1-hd3-c "=(Hh p -h d1 )P a / P a1-hd3-c ′

[0131] Gas injection height analysis error δ ha1 =(h a1-hd3-c ′-h a1-hd3-c ”) / h a1-hd3-c ′

[0132] P a1-hd3-0 <P a1-hd3-c ′ <P a1

[0133] P is calculated iteratively using the bisection method. a1-hd3-c ′, until δ ha1 Meeting the error requirements, the final draft depth h was determined. d3 Pressure value P in the control area 1 after inflation a1-hd3-c .

[0134] Phase 4: Keep all compartment exhaust valves closed, and control the semi-submersible barge to descend to the barrel foundation draft = h. w At this point, the asymmetric barrel foundation begins to float.

[0135] ③h d1 <h d2 <0

[0136] The descent is divided into three stages, such as Figure 11 As shown:

[0137] When and h d2 The large absolute value indicates that all compartments of the entire barrel foundation need to be inflated with a large amount of air. In other words, the buoyancy of the original structure after sinking without deflating is less than the structure's own weight. It is recommended to use buoyancy-assisted measures or to optimize the structure.

[0138] When h d1 and h d2 The smaller absolute value indicates that the barrel foundation only requires slight inflation, and the descent can be divided into three stages:

[0139] Phase 1: Keep all vent valves in the barrel compartment closed, and control the semi-submersible barge to submerge to the barrel base draft depth h. d3 =2h w / 3, (To avoid insufficient bottom sealing water thickness, submerge the entire bucket foundation to a certain depth), and then immediately stop submerging;

[0140] Phase Two: Keep all compartment vent valves closed and maintain the semi-submersible barge's draft at the bucket foundation depth of h. d3 Synchronously inflate the compartments within control area 1 until the air pressure reaches the preset value P. a1-hd3-c Then, synchronous inflation is performed on the inner compartment of control area 2 until the air pressure reaches the preset value P. a2-hd3-c .

[0141] The draft of the bucket foundation is h d3 The corresponding freeboard height h 0-d3 =Hh d3 .

[0142] First, using the ideal gas law and the principle of communicating vessels, the relationship between cabin pressure and diving depth under non-venting diving conditions is derived:

[0143] P a ·(Hhp ) = P a1 ·(Δh w1 +h0-h p )

[0144] P a1 =P a +Δh w1 ·γ w

[0145] By combining the above equations, a trial calculation is performed to determine the depth of descent to the draft = h. d3 Air pressure P in time control zone i ai-hd3-0 .

[0146] With basic draft = h d3 At that time, gas was synchronously injected into all compartments within control area i. To simplify the analysis, the changes in basic draft and freeboard caused by gas injection were ignored in the theoretical analysis.

[0147] The height of the air column after inflation, determined by its operating principle, is as follows:

[0148] h ai-hd3-c ′=(P ai-hd3-c ′-P a ) / γ w +h 0-d3 -h p

[0149] From the ideal gas formulas for the two states of stable gas injection and floating, we can obtain:

[0150] h ai-hd3-c "=(Hh p -h di )P a / P ai-hd3-c ′

[0151] Gas injection height analysis error δ hai =(h ai-hd3-c ′-h ai-hd3-c ”) / h ai-hd3-c ′

[0152] P ai-hd3-0 <P ai-hd3-c ′ <P ai

[0153] P is calculated iteratively using the bisection method. ai-hd3-c ′, until δ hai Meeting the error requirements, the final draft depth h was determined. d3 Pressure value P in the control area 1 after inflation ai-hd3-c .

[0154] Phase 3: Keep all compartment exhaust valves closed and control the semi-submersible barge to descend to the barrel foundation draft = h. w At this point, the asymmetric barrel foundation begins to float.

[0155] In this embodiment, Figure 8 The exhaust depth of compartment 1 in the central control area is <0, indicating that the compartment in control area 1 needs to be replenished with air. d1 = -0.722m < 0 ≤ h d2 =3.281m;

[0156] The dive is divided into 3 stages:

[0157] Phase 1: Maintain all compartment exhaust valves closed in Control Zone 1 and all compartment exhaust valves open in Control Zone 2, and control the semi-submersible barge to submerge to the barrel foundation draft h. d2 =3.281m, then immediately stop the descent, and after the air pressure inside and outside the tank is equalized, close the exhaust valves of all compartments in control area 2;

[0158] Phase Two: Keep all compartment vent valves closed and control the semi-submersible barge to descend to the barrel foundation draft depth h. d3 =(h d2 +h w The descent was immediately halted, and the cabin in control area 1 was synchronously inflated until the air pressure reached the preset value P. (P / 2 = 8.091m) a1-hd3-c =146.23.

[0159] P a1-hd3-c The calculation process is as follows:

[0160] First, using the ideal gas law and the principle of communicating vessels, the relationship between cabin pressure and diving depth under non-venting diving conditions is derived:

[0161] P a ·(Hh p ) = P a1 ·(Δh w1 +h0-h p )

[0162] That is, 101.3 × (14 - 0.5) = P a1 ·(Δh w1 +5.909-0.5);

[0163] P a1 =P a +Δh w1 ·γ w

[0164] That is, P a1 =101.3+Δhw1 10.045;

[0165] By combining the above equations, the air pressure P in control area 1 was determined by trial calculation when the submersion reached a draft of hd3 = 8.091m. a1-hd3-0 =143.044 kPa.

[0166] With basic draft = h d3 At that time, gas was synchronously injected into all compartments in control area 1. To simplify the analysis, the changes in basic draft and freeboard caused by gas injection were ignored in the theoretical analysis.

[0167] The height of the air column after inflation, determined by its operating principle, is as follows:

[0168] h a1-hd3-c ′=(P a1-hd3-c ′-P a ) / γ w +h 0-d3 -h p

[0169] From the ideal gas formulas for the two states of stable gas injection and floating, we can obtain:

[0170] h a1-hd3-c "=(Hh p -h d1 )P a / P a1-hd3-c ′

[0171] Gas injection height analysis error δ ha1 =(h a1-hd3-c ′-h a1-hd3-c ”) / h a1-hd3-c ′

[0172] P a1-hd3-0 <P a1-hd3-c ′ <P a1

[0173] P is calculated iteratively using the bisection method. a1-hd3-c ′, until δ ha1 Meeting the error requirements, the final draft depth h was determined. d3 Pressure value P in the control area 1 compartment after inflation at 8.091m a1-hd3-c =146.23 kPa, the iterative calculation process is as follows Figure 12 As shown.

[0174] Phase 3: Keep all compartment exhaust valves closed and control the semi-submersible barge to descend to the barrel foundation draft = h. w =12.9m, at which point the asymmetric bucket foundation begins to float.

[0175] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A method for pneumatic balancing of an asymmetric barrel foundation, characterized in that, include: Step S1: Divide the warehouse control area into i groups of control areas; Step S2: Determine the calculation parameters, and use computer-aided design software to obtain and process the data; Step S3: Calculate the air pressure inside the barrel at the moment of basic buoyancy by calculating the air pressure inside the barrel based on the principle of communicating vessels. Step S4: Calculate the constant tilt height of the barrel foundation at the moment of buoyancy, determine the initial position of the center of buoyancy, and calculate the constant tilt height; Step S5: Determine the basic phased descent plan. The phased descent plan is determined based on the exhaust descent height corresponding to each control zone.

2. The pneumatic balancing method for an asymmetric barrel foundation according to claim 1, characterized in that, The control zones are at least two groups, and usually two groups are selected. The parameters of the compartments within the same control zone are the same, while the parameters of different control zones are different.

3. The pneumatic balancing method for an asymmetric barrel foundation according to claim 1, characterized in that, In step S2, the parameters include: the total cross-sectional area of ​​each control area, the distance from the centroid of the total cross-section to the central axis of the lower bucket, the cavity area of ​​each compartment, and the distance from the centroid of the cavity of each compartment to the central axis of the lower bucket.

4. The pneumatic balancing method for an asymmetric bucket foundation according to claim 3, characterized in that, After determining the parameters, data processing is performed, including: Calculate the sum of the cavity areas of each compartment within each control area, A. hi The formula used is: Calculate the sum of the concrete cross-sectional areas A within each control area. ci The formula used is: A ci =A si -A hi ; Calculate the distance L from the centroid of the total concrete cross-sectional area in each control area to the central axis of the lower bucket. ci The formula used is: in, Let A be the cavity area of ​​the j-th compartment within the i-th control zone. si Let L be the total cross-sectional area of ​​the i-th control region. si is the distance from the centroid of the entire cross section of the i-th control area to the central axis of the lower barrel; mi represents the total number of compartments in the i-th control area.

5. The pneumatic balancing method for an asymmetric barrel foundation according to claim 1, characterized in that, Step S3 includes: Step S31, input the known parameters; Step S32, the liquid level difference Δh between inside and outside control zone 1. w1 Assignment; Step S33, calculate the liquid level difference Δh inside and outside control zone 2 based on force balance. w2 ; Step S34: Calculate the liquid level difference Δh inside and outside the control zone 2 based on torque balance. w2 ; Step S35: Calculate the iteration error; Step S36, iterative calculation: when the iterative error δ≥e, repeat steps S32-S35 until the error meets the requirements; e is the set allowable error range. Step S37: Calculate the air pressure state inside the barrel.

6. The pneumatic balancing method for an asymmetric barrel foundation according to claim 5, characterized in that, Step S33 uses the following formula: Δh w2 =[V0-h w ·(A c1 +A c2 )-Δh w1 ·A h1 ] / A h2 Where V0 is the basic drainage volume, h w For the draft of the bucket foundation, A c1 A is the sum of the cross-sectional areas of the concrete in the control zone 1. c2 A is the sum of the cross-sectional areas of the concrete in the control zone 2. h1 A is the sum of the cavity areas of all compartments within control area 1. h2 This is the sum of the cavity areas of all compartments within control zone 2; Step S34 uses the following formula: Δh w2 ′=[(Δh w1 ·A s1 ·L s1 +h sw1 ·A c1 ·L c1 )-h sw2 ·A c2 ·L c2 -Z0] / (A s2 ·L s2 ) h swi =h w -Δh wi Among them, A s1 and A s2 L represents the total cross-sectional area of ​​the first and second control zones. s1 and L s2 h is the distance from the centroid of the entire cross-section of the first and second control areas to the central axis of the lower bucket. sw1 h sw2 and h swi L represents the bottom sealing water height in the 1st, 2nd, and i-th control zones. c1 and L c2 Z0 is the distance from the centroid of the total concrete cross-sectional area in the first and second control areas to the central axis of the lower bucket; Z0 is the drainage volume displacement corresponding to the asymmetric moment of the asymmetric bucket foundation structure itself; Δh wi The difference in liquid level between the inside and outside of control zone i; Step S35 uses the formula δ=|Δh w2 -Δh w2 ′| / Δh w2 δ is the iteration error; Step S37 uses the formula: P ai =P a +Δh wi ·γ w P ai Let γ be the air pressure inside the barrel in the i-th control zone. w For the specific gravity of seawater, P a =101.325 kPa, which is the standard atmospheric pressure.

7. The pneumatic balancing method for an asymmetric barrel foundation according to claim 1, characterized in that, In step S4, the initial buoyancy center position is calculated using the following formula: Y c The initial position of the center of buoyancy; The constant tilt height is calculated using the following formula: a=Y G -AND C Where m is the constant inclination height, ρ is the constant inclination diameter, V0 is the structural drainage volume, and Y... G Let 'a' be the location of the structure's center of gravity, 'a' be the distance from the center of gravity to the center of buoyancy, 'I' be the moment of inertia of the structure's cross-section at the water surface regarding its longitudinal and transverse central axes, and 'i' be the distance from the center of gravity to the center of buoyancy. j Let n be the moment of inertia of the ballast water surface in the j-th compartment on the longitudinal and transverse central axes of that water surface, and n be the total number of compartments. l This represents the total number of compartments perpendicular to the calculation axis.

8. The pneumatic balancing method for an asymmetric barrel foundation according to claim 1, characterized in that, In step S5, the exhaust submersion height corresponding to each control zone is calculated using the following formula: h di =H-h p -P ai / P a ·(Δh wi +h0-h p ) Among them, h di H is the exhaust submersion height of the i-th control zone, H is the bottom height of the barrel foundation, and h is the bottom height of the barrel. p h0 is the thickness of the top cover plate of the barrel foundation, and h0 is the freeboard height.

9. The pneumatic balancing method for an asymmetric bucket foundation according to claim 1, characterized in that, In step S5, if the number of control zones is 2, the phased diving scheme can be divided into three types: 0≤h d1 <h d2 It is divided into 3 stages; h d1 <0≤h d2 It is divided into 4 stages; h d1 <h d2 <0, divided into 3 stages; h d1 The exhaust depth of control zone 1; h d2 The exhaust depth of control zone 2.

10. The pneumatic balancing method for an asymmetric barrel foundation according to claim 9, characterized in that, Each diving scheme controls the semi-submersible barge with bucket to descend to different drafts of the bucket foundation by adjusting the chamber's exhaust valve and inflating the chamber, ultimately controlling the descent to the bucket foundation's draft h. w Asymmetric barrel foundation for floating.

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