A vortex well construction anti-floating structure and construction method thereof

Abstract

The application provides a construction anti-floating structure of a vortex well and a construction method thereof. The anti-floating structure is formed by using a support pile during construction of the vortex well, and comprises a plurality of buffer grooves formed by digging near one side of a vortex well wall of the support pile and fixed reinforcing bars reserved when the vortex well wall is reinforced, one part of the fixed reinforcing bars is used as a main reinforcing bar and is poured into the vortex well wall, and the other part of the fixed reinforcing bars is inserted into the corresponding buffer groove. When the vortex well wall is reinforced after the foundation pit is excavated to the design bottom elevation, the buffer groove is dug in the support pile body at each top elevation area, the fixed reinforcing bar is inserted into the top position of the buffer groove, the construction anti-floating structure uses the anti-floating force of the support pile structure and the dead weight to prevent the vortex pool from floating up due to the high water level during the construction process, a certain distance is reserved at the lower part of the buffer groove to prevent the vortex pool from being pulled and cracked after the construction of the vortex pool is completed, and the support pile is used as the construction anti-floating structure to generate the anti-floating effect.

Description

Technical Field

[0001] The present invention belongs to the field of vortex well construction in the metallurgical industry, and specifically relates to an anti-floating structure for vortex well construction and a construction method thereof. The anti-floating structure is used for anti-floating vortex wells in strata with relatively high water levels during construction using deep foundation pit support piles. The anti-floating structure has simple construction and low cost, and reduces the depth of dewatering and the workload during vortex well construction. Background Art

[0002] During the construction of steel mills in the metallurgical industry, cyclone wells are one of the main water resource circulation systems in the steel mills. Wastewater is filtered, separated and purified through cyclone wells, so that water resources can be fully utilized.

[0003] The construction of the vortex well primarily utilizes conventional methods and consists of three major components: deep foundation pit support, earthwork, and the vortex well structure. Key features include deep excavation, abundant groundwater, and a high anti-floating water level in the strata, which necessitates high dewatering requirements for construction. Dewatering the foundation pit begins before excavation begins, and excavation and vortex well construction can only commence once the groundwater level meets construction requirements.

[0004] Typically, during foundation pit construction, the water level is required to be lowered to -50cm to -100cm from the bottom of the pit. When designing the main structure of the vortex well, anti-floating design calculations are considered within a certain range, either by increasing the main structure's deadweight or by directly increasing the gravity of the water stored in the well after completion. Therefore, throughout the construction period, as the height of the main structure of the vortex well wall increases and the vortex well gradually forms a whole, continuous dewatering and drainage work is required in and around the foundation pit to ensure that the water level remains at -50cm to -100cm from the bottom of the pit. At the same time, if necessary, temporary loads and counterweights are added to the bottom of the well to ensure that the vortex well does not generate significant buoyancy due to rising groundwater levels during construction, causing the main structure to float. However, during rainy seasons or heavy rainstorms, high groundwater levels or sudden increases in the water level within the well can still cause the main structure of the vortex well to float. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides an anti-floating structure for vortex well construction and a construction method thereof. According to the method, during the construction of the vortex well wall, reserved dowels are inserted into the buffer grooves of the supporting pile bodies. The reserved dowels and the vortex well wall form a whole. The overall structure formed by the foundation pit support generates downward gravity, thereby preventing or avoiding the floating of the vortex well body due to the increase in buoyancy caused by the rising groundwater level during the construction process.

[0006] In order to achieve the above technical purpose, the application provides a construction anti-floating structure of a vortex well, characterized in that: the anti-floating structure is formed by using a support pile during construction of the vortex well, and comprises a plurality of buffer grooves dug on one side of the support pile adjacent to a well wall of the vortex well and fixed insert bars reserved when reinforcing bars of the well wall of the vortex well are bound, a part of the fixed insert bars being poured into the well wall of the vortex well as main bars, and the other part being inserted into the corresponding buffer grooves; and the part inserted into the buffer grooves is in a vertical state with the part inserted into the well wall of the vortex well.

[0007] In a preferred technical scheme of the application, the buffer grooves horizontally extend from one side of the support pile adjacent to the well wall of the vortex well into the support pile body, a vertical section of each buffer groove is a half circle at the top and a gradually changing trapezoid at the bottom, the diameter of the half circle at the top is equal to the diameter d of the fixed insert bar, the width of the upper section of the gradually changing trapezoid at the bottom is d, and the width of the lower section is d+10 mm; the overall height of the half circle area and the gradually changing trapezoid of the buffer groove is 2d-3d, and the depth of the horizontal extension of the buffer groove into the support pile body is 10d-15d.

[0008] In a preferred technical scheme of the application, the fixed insert bar is an inverted L-shaped insert bar, the vertical part of which is fixed in the well wall of the vortex well as the main bar of the well wall, and the horizontal part is inserted into the buffer groove; the diameter d of the fixed insert bar is greater than or equal to the design diameter of the main bar of the well wall of the vortex well.

[0009] In a preferred technical scheme of the application, the buffer grooves are equally spaced in the vertical and horizontal directions of the support pile, and the vertical spacing between adjacent two buffer grooves is mostly 2.5-5.0 m, and the horizontal spacing is 1.2-4.8 m.

[0010] In a further technical scheme of the application, the total number N of the fixed insert bars and the horizontal spacing l of the single circle of the fixed insert bars are determined according to the anti-floating design calculation of the underground water, so as to ensure that the total anti-floating force provided by the self weight of the vortex well and the insert bars at any moment during construction is greater than or equal to the floating force generated by the vortex well structure, and the specific calculation process is as follows:

[0011] n i =πD i / l i

[0012] N=n1+n2+....+n i

[0013] f s ×F 浮i ≤(n1×F 抗浮1 +...+n i ×F 抗浮i )+G i

[0014] f s ×F 浮 ≤N×F 抗浮 +G

[0015] F 浮 =γ w ×V

[0016] Where: n i The number of fixed reinforcing bars in a certain layer at a certain moment of construction;

[0017] D i The outer diameter of the vortex well at a certain moment of construction, unit: m;

[0018] l i To fix the horizontal spacing of the inserted reinforcement at a certain moment of construction;

[0019] N is the total number of fixed reinforcing bars in the swirl well;

[0020] f s For the anti-floating safety calculation factor, it can be taken as 1.2;

[0021] F 浮 is the buoyancy generated by the swirl well structure, unit: kN;

[0022] F 浮i The buoyancy generated by the vortex well structure at a certain moment of construction (kN);

[0023] F 抗浮 Provides anti-buoyancy force for a single fixed dowel, unit: kN;

[0024] F 抗浮i The total anti-buoyancy force (kN) provided by the horizontal fixed reinforcement of a certain layer at a certain moment of construction;

[0025] G is the deadweight of the vortex well, unit: kN;

[0026] G i The deadweight of the vortex well at a certain moment of construction (kN);

[0027] γ w is the water density, take 10KN / m 3 ;

[0028] V is the volume within the outer edge of the vortex well that has been completed and is located below the groundwater level, in m 3 .

[0029] The preferred technical solution of the present invention is: the diameter d of the fixed dowel and the horizontal depth h of the buffer groove, that is, the horizontal depth h of the fixed dowel inserted into the buffer groove 槽, through groundwater anti-floating design calculation and inserted reinforcement force verification calculation, it is ensured that the inserted reinforcement will not be sheared or damaged by shear bending failure due to insufficient shear strength, and that relative displacement will not occur due to insufficient relative friction caused by insufficient insertion depth of the inserted reinforcement into the buffer groove. The verification process is as follows:

[0030]

[0031] F 抗浮 =F 抗剪 +F 摩擦

[0032] F 抗剪 =0.25πd 2 ×f v

[0033] F 摩擦 =f rb ×s

[0034] s=π×d×h 槽 ×50%

[0035] h 槽 =10d~15d

[0036] Among them: F 抗剪 F is the shear strength that a single fixed dowel can provide (kN); 摩擦 is the limit friction force (kN) that a single fixed dowel can provide when inserted into the buffer groove; d is the diameter of the fixed dowel (m); f ... v is the design value of shear strength of a single fixed dowel (kN / m 2 ); s is the surface area of ​​the contact part between the fixed dowel in the buffer groove and the buffer groove (m 2 ), which can be 50% of the total surface area; f rb is the friction coefficient between the fixed dowel and the inner wall of the buffer groove (kN / m 2 );h 槽 It is the horizontal depth (m) of the fixed dowel inserted into the buffer groove; the rest is the same as above.

[0037] The preferred technical solution of the present invention is as follows: the support piles are reinforced concrete cast-in-place piles; the length of the support piles, in addition to meeting the normal stable embedding requirements, should also meet the pull-out resistance requirements due to the buoyancy of groundwater transmitted to the pile body during the construction of the vortex well, which is specifically verified by the following formula:

[0038] f s ×F 浮 -G≤(0.5×∑α 1j ×q 1jsi ×L 1j ×πZ 1j +G 桩1 )+...+(0.5×∑αij ×q ijsi ×L ij ×πZ ij +G 桩i )

[0039] Where: α ij is the pull-out coefficient of the rock and soil on the j-th layer of the i-th supporting pile, q ijsi is the standard value of the ultimate friction resistance of the rock and soil layer on the jth side of the i-th supporting pile (kPa), L ij is the length of the rock and soil of the i-th supporting pile located on the j-th layer (m); Z ij is the diameter of the rock pile of the i-th supporting pile located on the j-th layer, G 桩i is the deadweight of the ith supporting pile (kN).

[0040] In order to achieve the above technical objectives, the present invention also provides a construction method for an anti-floating structure for a vortex well, which is characterized by the following specific steps:

[0041] S1. Obtain the construction parameters of the support piles and vortex wells through the corresponding project geotechnical engineering investigation report, the construction design drawings of the support piles and vortex wells, and the engineering specifications, and calculate the buoyancy F generated during the construction of the vortex wells. 浮 ; Select steel bars with a diameter d greater than or equal to the diameter of the main reinforcement of the vortex well wall as fixed dowel bars, and determine the total number of fixed dowel bars N according to the following formula:

[0042] f s ×F 浮 ≤N×F 抗浮 +G

[0043] Where: f s For the anti-floating safety calculation factor, it can be taken as 1.2;

[0044] F 浮 is the buoyancy generated by the swirl well structure, unit: kN;

[0045] F 抗浮 Provides anti-buoyancy force for a single fixed dowel, unit: kN;

[0046] G is the deadweight of the vortex well, unit: kN;

[0047] S2. According to the fixed dowel selected in step S1, determine the horizontal depth of the buffer groove, i.e. the depth h of the fixed dowel inserted into the buffer groove, based on the groundwater anti-floating design calculation and dowel stress verification. 槽 Ensure that the inserted reinforcement is not sheared or damaged due to shear bending failure due to insufficient shear strength, and that the relative friction is too small due to insufficient insertion depth of the inserted reinforcement into the buffer groove, resulting in relative displacement, which in turn causes the inserted reinforcement to fail or the vortex well to float, thereby affecting the vortex well construction; the verification process is as follows:

[0048]

[0049] F 抗浮 =F 抗剪 +F 摩擦

[0050] F 抗剪 =0.25πd 2 ×f v

[0051] F 摩擦 =f rb ×s

[0052] s=π×d×h 槽 ×50%

[0053] h 槽 =10d~15d

[0054] Among them: F 抗剪 F is the shear strength that a single fixed dowel can provide (kN); 摩擦 is the limit friction force that a single fixed dowel can provide when entering the buffer groove (kN); d is the diameter of the fixed dowel (m); f v is the design value of shear strength of a single fixed dowel (kN / m 2 ); s is the surface area of ​​the contact part between the fixed dowel in the buffer groove and the buffer groove (m 2 ), which can be 50% of the total surface area; f rb is the friction coefficient between the fixed dowel and the inner wall of the buffer groove (kN / m 2 );h 槽 is the horizontal depth of the fixed dowel inserted into the buffer groove (m); N is the total number of fixed dowels in the vortex well; the rest is the same as above;

[0055] S3. Determine the number N of reserved fixed dowels and the depth h of the fixed dowels inserted into the buffer groove 槽 After that, the number and horizontal depth of buffer grooves reserved on the support pile can be determined, and the size of a single reserved buffer groove can be determined according to the selected fixed dowel diameter d. The buffer groove is a structure with a semicircular upper part and a gradually tapered trapezoidal lower part. The diameter of the upper semicircle is equal to the diameter d of the fixed dowel, the upper cross-sectional width of the lower gradually tapered trapezoid is d, and the lower cross-sectional width is d+10mm. The semicircular area of ​​the buffer groove and the overall height of the gradually tapered trapezoid are 2d~3d, and the buffer groove extends horizontally to the depth of h in the support pile body. 槽 Then, the layout of the buffer tanks is designed according to the vertical spacing between two adjacent buffer tanks of 2.5 to 5.0 meters and the horizontal spacing of 1.2 to 4.8 meters;

[0056] S4, after the layout parameters of the fixed insert and the buffer groove are determined, the construction of the vortex well is started, first, the foundation pit support structure is constructed, after the construction of the foundation pit support structure is completed, the foundation pit drainage and earth excavation are carried out, after the excavation is carried out to the design well bottom elevation of the vortex well, the main structure construction of the vortex well is started, and before the reinforcement of the well wall is bound, the buffer groove positioning is carried out according to the parameters determined in the steps S1 to S3, and the buffer groove is chiseled by using a pneumatic pick or an electric hammer;

[0057] S5, after the buffer groove is chiseled, the reinforcement of the vortex well wall in the corresponding area is bound, and the fixed insert is bound at the same time, the well wall part is bound with the main structure reinforcement of the well wall, and the inserted part should be vertically inserted into the buffer groove, so that the fixed insert is located at the top of the semicircular buffer groove; after the reinforcement is bound, the concrete pouring of the vortex well at this layer is completed.

[0058] The preferred technical scheme of the present application: in the step S4, the reinforcement of the support pile is avoided when the buffer groove is chiseled, and after the buffer groove is chiseled, the residues in the groove are cleaned by using air blowing or water flushing, so that the fixed insert can be smoothly inserted; in the step S5, the well wall part is firmly bound, so that the fixed insert will not be loose and will not move downward during the concrete pouring process; in the step S5, during the construction of the vortex well, the total anti-floating force provided by the self-weight of the vortex well that has been constructed and the fixed insert that has been installed is calculated, when the sum of the self-weight of the vortex well that has been constructed and the total anti-floating force provided by the fixed insert that has been constructed is less than the floating force generated by the structure of the vortex well that has been constructed, the number of the fixed insert is increased or the large-diameter fixed insert is replaced to adjust, so that the sum of the self-weight of the vortex well that has been constructed and the total anti-floating force provided by the fixed insert that has been constructed is greater than or equal to the floating force generated by the structure of the vortex well that has been constructed at any time during the construction, and the calculation process is as follows:

[0059] n i = πD i / l i

[0060] f s × F 浮i ≤ (n1× F 抗浮1 +...+ n i × F 抗浮i )+ G i

[0061] F 浮i = γ w × V i

[0062] Wherein: n i is the number of the fixed insert of a certain layer in the horizontal direction at a certain time during the construction;

[0063] D i is the outer diameter of the vortex well at a certain time during the construction, unit: m;

[0064] l i To fix the horizontal spacing of the inserted reinforcement at a certain moment of construction;

[0065] f s For the anti-floating safety calculation factor, it can be taken as 1.2;

[0066] F 浮i The buoyancy generated by the vortex well structure at a certain moment of construction (kN);

[0067] F 抗浮i The total anti-buoyancy force (kN) provided by the horizontal fixed reinforcement of a certain layer at a certain moment of construction;

[0068] G i The deadweight of the vortex well at a certain moment of construction (kN);

[0069] γ w is the water density, take 10KN / m 3 ;

[0070] V i The volume within the outer contour of the vortex well below the groundwater level at a certain moment of construction, in m 3 .

[0071] A preferred technical solution of the present invention is as follows: in step S4, before the construction of the foundation pit support structure, the length of the support pile body is verified to meet the pull-out resistance requirement due to the buoyancy of groundwater transmitted to the pile body, ensuring that the sum of the deadweight of the used support piles and the ultimate pull-out resistance that the used support piles can provide at any time is greater than or equal to the difference between the buoyancy generated by the constructed vortex well structure and the deadweight of the constructed vortex well, as follows:

[0072] f s ×F 浮 -G≤(0.5×∑α 1j ×q 1jsi ×L 1j ×πZ 1j +G 桩1 )+...+(0.5×∑α ij ×q ijsi ×L ij ×πZ ij +G 桩i )

[0073] Where: α ij is the pull-out coefficient of the rock and soil on the j-th layer of the i-th supporting pile, q ijsi is the standard value of the ultimate friction resistance of the rock and soil layer on the jth side of the i-th supporting pile (kPa), L ij is the length of the rock and soil of the i-th supporting pile located on the j-th layer (m); Z ijis the diameter of the rock pile of the i-th supporting pile located on the j-th layer, G 桩i is the deadweight of the ith supporting pile (kN).

[0074] The buffer groove of the present invention is easy to dig, has low technical requirements and low construction cost; the reserved dowel bar binding operation is simple, has low technical requirements and low construction cost; the reserved dowel bar is easy to insert into the buffer groove, has low technical requirements and low construction cost.

[0075] The anti-floating structure of the present invention is based on the corresponding elevation and water level observation data of each auxiliary vortex well constructed during the anti-floating design calculation and construction process. During the vortex well wall casting construction process, as the casting height increases, the construction requirement for the groundwater level can also rise accordingly, thereby overcoming the problems of long dewatering period, large depth and heavy workload during the vortex well construction process, reducing the construction dewatering water level requirements and the water-stop curtain construction cost during the entire construction process; reducing the waste of groundwater resources; and reducing the corresponding anti-floating measures such as increasing the pit bottom load, raft plate thickness, and well wall thickness during the construction process; shortening the dewatering construction period and dewatering intensity, reducing the additional workload of dewatering and anti-floating, reducing construction costs, and making effective use of support piles.

[0076] In the present invention, when the foundation pit is excavated to the designed bottom elevation and the reinforcement for each vortex well wall is tied, a buffer groove is excavated in the support pile body at each top elevation area. When the reinforcement for the vortex well wall is tied, a reserved dowel bar is inserted into the top position of the buffer groove. The present invention utilizes the dowel bar reserved during the vortex well wall construction process to insert it into the buffer groove of the support pile body. The reserved dowel bar and the vortex well wall are integrated. The downward gravity generated by the integral structure formed by the support and the pull-out resistance of the support pile structure is utilized to prevent or avoid the vortex well body from floating due to the increased buoyancy of the rising groundwater level during the vortex well construction. A certain distance is reserved below the buffer groove to prevent post-construction settlement of the vortex pool from causing tensile damage to the well wall. The support piles are used as an anti-floating structure to produce an anti-floating effect during construction.

[0077] The present invention has a simple overall structure, low cost, and easy construction process operation, which reduces the dewatering depth and workload during the construction of the vortex well; reduces the need to increase the pit bottom load, raft plate thickness, well wall thickness and other corresponding anti-floating measures during the construction process; shortens the construction period, reduces construction costs, and effectively utilizes the support piles in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 It is a schematic cross-sectional structure diagram of the present invention;

[0079] Figure 2 It is a schematic diagram of the top structure of the present invention;

[0080] Figure 3 Schematic diagram of the detailed structure of the anti-floating structure in the present invention;

[0081] Figure 4 It is a vertical cross-sectional schematic diagram of the buffer tank in the present invention;

[0082] Figure 5 It is a schematic transverse cross-sectional view of the buffer tank in the present invention.

[0083] In the figure: 1 - vortex well wall, 2 - support piles, 3 - buffer groove, 4 - fixed dowel bars, 5 - vortex well. DETAILED DESCRIPTION

[0084] The present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 5 The accompanying drawings are simplified versions of the embodiments and are only used to clearly and concisely illustrate the embodiments of the present invention. The technical solutions shown in the accompanying drawings are specific solutions of the embodiments of the present invention and are not intended to limit the scope of the invention claimed for protection. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0085] In the description of the present invention, it should be understood that the terms "vertical", "top", "steel bar diameter d", "2d~3d", "10d~15d", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the equipment or components referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0086] It should also be noted that, unless otherwise expressly specified or limited, the locations and quantities of fixed dowels and corresponding buffer grooves are intended solely to facilitate the description and simplify the present invention, and do not indicate or imply that the devices or components referred to must have specific locations and quantities. Therefore, they should not be construed as limitations on the present invention. Designers skilled in the art will understand the specific meanings of the above terms in the present invention based on their specific circumstances.

[0087] The embodiment provides an anti-floating structure for vortex well construction, such as Figures 1 to 5As shown, the anti-floating structure is constructed using support piles 2 during the construction of the vortex well 5, including multiple buffer grooves 3 dug on one side of the support piles 2 adjacent to the vortex well wall 1 and fixed dowel bars 4 reserved when the steel bars of the vortex well wall 1 are tied. The buffer grooves 3 are evenly spaced along the vertical and horizontal directions of the support piles 2, and the vertical spacing between two adjacent buffer grooves 3 is mostly 2.5 to 5.0 meters, and the horizontal spacing is 1.2 to 4.8 meters. The buffer grooves 3 extend horizontally from the side of the support pile 2 adjacent to the vortex well wall 1 into the support pile 2. Each buffer groove 3 has a vertical cross-section with a semicircular top and a tapered trapezoidal bottom. The diameter of the semicircular top is equal to the diameter d of the fixed dowel 4. The width of the upper section of the tapered trapezoidal bottom section of the buffer groove 3 is d, and the width of the lower section is d+10mm. The combined height of the semicircular area and the tapered trapezoidal bottom section of the buffer groove 3 is 2d-3d, and the buffer groove 3 extends horizontally into the support pile 2 to a depth of 10d-15d. Part of the fixed dowel 4 is cast into the vortex well 5 wall as the main reinforcement, while the other part is inserted into the corresponding buffer groove 3, with the portion inserted into the buffer groove 3 perpendicular to the portion inserted into the vortex well wall 1. The fixed dowel 4 is an inverted L-shaped dowel. Its vertical portion is fixed to the vortex well wall 1 as the main reinforcement, while the transverse portion is inserted horizontally into the buffer groove 3.

[0088] The embodiment provides a method for constructing an anti-floating structure for a vortex well, and the specific steps are as follows:

[0089] S1. Obtain the construction parameters of the support piles and vortex wells through the corresponding project geotechnical engineering investigation report, the construction design drawings of the support piles and vortex wells, and the engineering specifications, and calculate the buoyancy F generated during the construction of the vortex wells. 浮 , only need to have the outer contour diagram of the vortex well and the groundwater depth, the volume of groundwater encroached by the vortex well can be calculated, and then according to the Archimedes principle, the buoyancy of the vortex well can be calculated; specifically, the pull-out coefficient α of each support pile in each side rock and soil layer, the standard value of the ultimate friction resistance q of each support pile in each side rock and soil layer can be determined through the corresponding project geotechnical engineering survey report. si and the anti-floating water level of the site; obtain the deadweight G of each support pile through the construction drawings and construction records of the support piles and vortex wells 桩 , the deadweight G of the swirl well and the design height H of the swirl well; obtain the friction coefficient f between the reserved dowel and the inner wall of the buffer groove through specification query rbField tests can also be conducted to verify the rationality of the parameters. The allowable settlement value of the vortex well and the stress on the vortex well wall structure during the construction design phase can be obtained based on the vortex well construction drawings. The water-stop curtain and construction dewatering design during the construction design phase are special designs of the inherent vortex well construction drawings and can be directly obtained and used. The process can be supplemented by groundwater level monitoring and verification. The parameters used in the calculation process of the embodiment can all be obtained through on-site survey data, design drawings, or specification inquiries. Fixed dowel diameter d and dowel shear strength design value f v It can be obtained from the factory nameplate of the dowel. Before construction, the diameter d of the fixed dowel is determined first. The steel bars with a diameter d greater than or equal to the diameter of the main reinforcement of the vortex well wall are used as fixed dowels. Based on the selected fixed dowels, the total number of fixed dowels N can be determined according to the following formula:

[0090] f s ×F 浮 ≤N×F 抗浮 +G

[0091] Where: f s For the anti-floating safety calculation factor, it can be taken as 1.2;

[0092] F 浮 is the buoyancy generated by the swirl well structure, unit: kN;

[0093] F 抗浮 Provides anti-buoyancy force for a single fixed dowel, unit: kN;

[0094] G is the deadweight of the vortex well, unit: kN.

[0095] S2. According to the fixed dowel selected in step S1, determine the horizontal depth of the buffer groove, i.e. the depth h of the fixed dowel inserted into the buffer groove, based on the groundwater anti-floating design calculation and dowel stress verification. 槽 Ensure that the inserted reinforcement is not sheared or damaged due to shear bending failure due to insufficient shear strength, and that the relative friction is too small due to insufficient insertion depth of the inserted reinforcement into the buffer groove, resulting in relative displacement, which in turn causes the inserted reinforcement to fail or the vortex well to float, thereby affecting the vortex well construction; the verification process is as follows:

[0096]

[0097] F 抗浮 =F 抗剪 +F 摩擦

[0098] F 抗剪 =0.25πd 2 ×f v

[0099] F 摩擦 =f rb ×s

[0100] s=π×d×h 槽 ×50%

[0101] h 槽 =10d~15d

[0102] Among them: F 抗剪 F is the shear strength that a single fixed dowel can provide (kN); 摩擦 is the limit friction force that a single fixed dowel can provide when entering the buffer groove (kN); d is the diameter of the fixed dowel (m); f v is the design value of shear strength of a single fixed dowel (kN / m 2 ); s is the surface area of ​​the contact part between the fixed dowel in the buffer groove and the buffer groove (m 2 ), which can be 50% of the total surface area; f rb is the friction coefficient between the fixed dowel and the inner wall of the buffer groove (kN / m 2 );h 槽 is the horizontal depth (m) of the fixed dowels inserted into the buffer groove; N is the total number of fixed dowels in the vortex well; the rest are the same as above.

[0103] S3. Determine the number N of reserved fixed dowels and the depth h of the fixed dowels inserted into the buffer groove 槽 After that, the number and horizontal depth of buffer grooves reserved on the support pile can be determined, and the size of a single reserved buffer groove can be determined according to the selected fixed dowel diameter d. The buffer groove is a structure with a semicircular upper part and a gradually tapered trapezoidal lower part. The diameter of the upper semicircle is equal to the diameter d of the fixed dowel, the upper cross-sectional width of the lower gradually tapered trapezoid is d, and the lower cross-sectional width is d+10mm. The semicircular area of ​​the buffer groove and the overall height of the gradually tapered trapezoid are 2d~3d, and the buffer groove extends horizontally to the depth of h in the support pile body. 槽 ; Then, the layout plan of the buffer tank is designed according to the vertical spacing between two adjacent buffer tanks of 2.5 to 5.0 meters and the horizontal spacing of 1.2 to 4.8 meters.

[0104] S4. After the layout parameters of the fixed dowels and the buffer groove are determined, the construction of the vortex well is started. First, the foundation pit support structure is constructed. After the construction of the foundation pit support structure is completed, the foundation pit is dewatered and earthwork is excavated. After the excavation reaches the designed bottom elevation of the vortex well, the main structure of the vortex well is constructed. Before the reinforcement of the well wall is tied, the buffer groove on the support pile is positioned and laid out according to the parameters determined in steps S1 to S3, and the buffer groove is excavated with a jackhammer or an electric hammer; the reinforcement of the support pile is avoided when the buffer groove is excavated. After the excavation of the buffer groove is completed, the residue in the groove is cleaned by blowing with an air compressor or flushing with a water pipe to ensure that the fixed dowel is smoothly inserted; before the construction of the foundation pit support structure, the length of the support pile body is verified to meet the pull-out requirements transmitted to the pile body by the buoyancy of groundwater, and to ensure that the sum of the deadweight of the used support pile and the ultimate pull-out force that the used support pile can provide at any time should be greater than or equal to the difference between the buoyancy generated by the constructed vortex well structure and the deadweight of the constructed vortex well, as follows:

[0105] f s ×F 浮 -G≤(0.5×∑α 1j ×q 1jsi ×L 1j ×πZ 1j +G 桩1 )+...+(0.5×∑α ij ×q ijsi ×L ij ×πZ ij +G 桩i )

[0106] Where: α ij is the pull-out coefficient of the rock and soil on the j-th layer of the i-th supporting pile, q ijsi is the standard value of the ultimate friction resistance of the rock and soil layer on the jth side of the i-th supporting pile (kPa), L ij is the length of the rock and soil of the i-th supporting pile located on the j-th layer (m); Z ij is the diameter of the rock pile of the i-th supporting pile located on the j-th layer, G 桩i is the deadweight of the ith supporting pile (kN).

[0107] S5. After the buffer groove is excavated, the steel bars of the vortex well in the corresponding area are tied, and the fixed dowel bars are tied at the same time. The wall part is tied together with the steel bars of the main structure of the wall, and the inserted part should be vertically inserted into the buffer groove to ensure that the fixed dowel bars are in the semicircular position at the top of the buffer groove. After the steel bars are tied, the concrete pouring of this layer of the vortex well is completed; the wall part is tied firmly to ensure that the fixed dowel bars will not loosen or move down during the concrete pouring process; the vortex well is constructed by pouring concrete in layers, and the height of each layer is about 5m. During the construction of the vortex well, the total anti-buoyancy provided by the self-weight of each layer of the constructed vortex well and the installed fixed dowel bars are verified. When the sum of the self-weight of the constructed vortex well and the total anti-buoyancy provided by the constructed fixed dowel bars is less than the buoyancy generated by the constructed vortex well structure, adjustments are made by increasing the number of fixed bars or replacing large-diameter fixed bars to ensure that the sum of the self-weight of the constructed vortex well and the total anti-buoyancy provided by the constructed fixed dowel bars at any time of construction should be greater than or equal to the buoyancy generated by the constructed vortex well structure. The verification process is as follows:

[0108] n i =πD i / l i

[0109] f s ×F 浮i ≤(n1×F 抗浮1 +...+n i ×F 抗浮i )+G i

[0110] F 浮i =γ w ×V i

[0111] Where: n i The number of fixed reinforcing bars in a certain layer at a certain moment of construction;

[0112] D i The outer diameter of the vortex well at a certain moment of construction, unit: m;

[0113] l i To fix the horizontal spacing of the inserted reinforcement at a certain moment of construction;

[0114] f s For the anti-floating safety calculation factor, it can be taken as 1.2;

[0115] F 浮i The buoyancy generated by the vortex well structure at a certain moment of construction (kN);

[0116] F 抗浮i The total anti-buoyancy force (kN) provided by the horizontal fixed reinforcement of a certain layer at a certain moment of construction;

[0117] Gi The deadweight of the vortex well at a certain moment of construction (kN);

[0118] γ w is the water density, take 10KN / m 3 ;

[0119] V i The volume within the outer contour of the vortex well below the groundwater level at a certain moment of construction, in m 3 .

[0120] The present invention is further described below with reference to a specific embodiment. The embodiment is a vortex well in a steelmaking unit of a steel plant. The outer diameter of the outer cylinder wall of the vortex well is 35.2m, the inner diameter is 32m, the wall thickness is 1.6m, and the depth is 35.2m. During construction, the actual measured stable buried depth of the groundwater level was 9.50m. The vortex well was constructed using the sequential construction method, and the construction height of each section was 5.0m. The vortex well foundation pit was supported by concrete piles with a pile diameter of 1.0m and a pile length of 28.0m. There were a total of 90 support piles, with a reinforced concrete crown beam on the top, which was evenly arranged along the outer side of the cylinder wall, and the center distance between two adjacent piles was 1.2m.

[0121] The project used HRB400, 40mm diameter threaded steel bars. Horizontally, a single rebar planting point was set for every support pile, totaling 45 bars in a single circle. Vertically, the spacing was 5m, consistent with the construction height of each section, for a total of 7 circles, totaling 315 rebars. The rebars were inserted into the buffer groove 15 times the depth of the rebar diameter, 600mm, and the friction coefficient between the rebar and reinforced concrete was 0.7. The groundwater anti-floating design and steel bar stress verification calculations were as follows:

[0122] N = 45 * 7 = 315

[0123] F 浮 =γ w ×V=10*3.14*17.6 2 *(35.2-9.5)=249970.1kN

[0124] F 抗剪 =0.25πd 2 ×f v =0.25*3.14*0.04 2 *400*1000=502.4kN

[0125] F 摩擦 =f rb ×s=0.7*400*3.14*0.04*0.3*50%=5.2kN

[0126] G=3.14*(17.6 2 -16 2)*35.2*25=148549.6kN

[0127] F 抗浮 =315*(502.4+5.2)=159894.0kN

[0128] F 抗浮 +G=159894+148549.6=308443.6kN

[0129] F 浮 *1.2=249970.1*1.2=299964.1kN

[0130] 308443.6kN>299964.1kN, the groundwater anti-floating design and steel bar stress verification meet the requirements.

[0131] Based on the geological survey data and support pile construction records, the pull-out resistance requirements of the support piles of this project are verified, as shown below.

[0132] The maximum anti-buoyancy force required by the support piles is 1.2*249970.1-148549.6=151414.5kN

[0133] The pull-out resistance provided by a single support pile is 3.14*0.5*0.5*28*24+0.3*5000=2027.5kN;

[0134] A reinforced concrete cap beam is set on the top of the support pile, which can be considered as a whole. The total pull-out force provided by the corresponding support pile group is 90*2027.5=182475kN

[0135] 182475kN>151414.5kN, the pull-out calculation of the support piles meets the requirements.

[0136] The above embodiment uses support piles to prevent floating during the construction of the vortex well. The theoretical calculation is feasible and has been verified by field application: the on-site groundwater depreciation is dynamically adjusted. As the vortex well is constructed upward, the groundwater depreciation head height on the site also rises synchronously. It is only necessary to ensure that the groundwater is 0.5m below the current construction working surface. This can greatly reduce the workload of groundwater pumping and drainage. It is estimated that nearly 1 million cubic meters of groundwater can be avoided during the construction of this project; at the same time, this project does not set up anti-floating piles / anti-floating anchor rods, or deliberately increase the deadweight by increasing the wall thickness of the vortex well. Other separate anti-floating measures, such as increasing the deadweight by deliberately increasing the wall thickness of the vortex well, are not used. Only by using vortex well support piles and adopting the structure of the invention and the corresponding construction method for anti-floating, nearly 5 million yuan in anti-floating costs are saved; and there are no abnormalities in the on-site monitoring data. The main construction of this project has been completed and is awaiting production.

[0137] The above is merely one embodiment of the present invention, and its description is relatively specific and detailed. However, it should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, and such modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An anti-floating structure for vortex well construction, characterized by: The anti-floating structure is constructed by using support piles (2) during the construction of the vortex well (5), and includes a plurality of buffer grooves (3) dug on one side of the support pile (2) adjacent to the vortex well wall (1) and fixed dowel bars (4) reserved when the steel bars of the vortex well wall (1) are tied. A portion of the fixed dowel bars (4) is cast into the wall of the vortex well (5) as a main bar, and another portion is inserted into the corresponding buffer groove (3), and the portion inserted into the buffer groove (3) is in a vertical state with the portion inserted into the vortex well wall (1); The total number of fixed dowels (4) reserved is N, the number of fixed dowels reserved for a single circle horizontally is n, and the horizontal spacing of the fixed dowels in a single circle is l. These are all determined based on the design verification of groundwater anti-buoyancy, ensuring that the sum of the deadweight of the constructed vortex well and the total anti-buoyancy provided by the constructed dowels at any time of construction should be greater than or equal to the buoyancy generated by the constructed vortex well structure. The specific verification process is as follows: ； ； ； ； ； Where: n i The number of fixed reinforcing bars in a certain layer at a certain moment of construction; D i The outer diameter of the vortex well at a certain moment of construction, unit: m; l i is the horizontal spacing of fixed dowel bars at a certain moment of construction; N is the total number of fixed dowel bars in the swirl well; For the anti-floating safety calculation factor, it can be taken as 1.2; is the buoyancy generated by the swirl well structure, unit: kN; The buoyancy generated by the vortex well structure at a certain moment of construction (kN); Provides anti-buoyancy force for a single fixed dowel, unit: kN; The total anti-buoyancy force provided by the horizontal fixed reinforcement of a certain layer at a certain moment of construction (kN); is the deadweight of the vortex well, unit: kN; The deadweight of the vortex well at a certain moment of construction (kN); is the water density, take 10KN / m 3 ; The volume within the outer edge of the vortex well that has been completed and is located below the groundwater level, in m 3 .

2. The anti-floating structure for vortex well construction according to claim 1, characterized in that: The buffer groove (3) extends horizontally from a side of the support pile (2) adjacent to the vortex well wall (1) to the inside of the support pile (2). The vertical cross-section of each buffer groove (3) is semicircular at the top and gradually trapezoidal at the bottom. The diameter of the semicircular top is equal to the diameter d of the fixed dowel (4). The width of the upper cross-section of the gradually trapezoidal lower part of the buffer groove (3) is d, and the width of the lower cross-section is d+10mm. The overall height of the semicircular area and the gradually trapezoidal shape of the buffer groove (3) is 2d~3d. The buffer groove (3) extends horizontally to a depth of 10d~15d inside the support pile (2).

3. The anti-floating structure for vortex well construction according to claim 1 or 2, characterized in that: The fixed dowel (4) is an inverted L-shaped dowel, the vertical portion of which is fixed in the vortex well wall (1) as the main rib of the vortex well wall (1), and the transverse portion is horizontally inserted into the buffer groove (3); the diameter d of the fixed dowel (4) is greater than or equal to the designed diameter of the main rib of the vortex well wall (1).

4. The anti-floating structure for vortex well construction according to claim 1 or 2, characterized in that: The buffer grooves (3) are arranged at equal intervals along the vertical and horizontal directions of the support piles (2), and the vertical spacing between two adjacent buffer grooves (3) is 2.5 to 5.0 m, and the horizontal spacing is 1.2 to 4.8 m.

5. The anti-floating structure for vortex well construction according to claim 1, characterized in that: The diameter d of the fixed dowel (4) and the horizontal depth of the buffer groove (3), i.e., the horizontal depth of the fixed dowel inserted into the buffer groove, are , through groundwater anti-floating design calculation and inserted reinforcement force verification calculation, it is ensured that the inserted reinforcement will not be sheared or damaged by shear bending failure due to insufficient shear strength, and that relative displacement will not occur due to insufficient relative friction caused by insufficient insertion depth of the inserted reinforcement into the buffer groove. The verification process is as follows: ； ； ； ； ； = 10d~15d; in: The shear strength that a single fixed dowel can provide (kN); is the limit friction force that a single fixed dowel can provide when inserted into the buffer groove (kN); d is the diameter of the fixed dowel (m); is the design value of shear strength of a single fixed dowel (kN / m 2 ); is the surface area of ​​the contact part between the fixed dowel and the buffer groove (m 2 ), which can be taken as 50% of the overall surface area; is the friction coefficient between the fixed dowel and the inner wall of the buffer groove (kN / m 2 );h 槽 It is the horizontal depth (m) of the fixed dowel inserted into the buffer groove; the rest is the same as above.

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