Improved channel lining board repairs cofferdam base structure
By setting multiple elastic supports on the cofferdam base for channel lining repair, the problem of uneven load transfer on uneven lining plates in existing technologies is solved, achieving safe and reliable channel repair and reducing construction and operation risks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA SOUTH-TO-NORTH WATER DIVERSION GRP MIDDLE LINE CO LTD
- Filing Date
- 2026-04-17
- Publication Date
- 2026-05-29
AI Technical Summary
The existing channel lining plate repair cofferdam base structure is difficult to achieve uniform load transfer when adapting to uneven concrete lining plates, which makes construction difficult, operation risky, and there is a risk of local pressure overload causing lining plate cracking.
The U-shaped inverted cofferdam, divided into multiple segments along the channel slope, is equipped with multiple elastic supports, including guide bearings, plunger rods, spherical bearings, and anti-slip pads. Through the adaptive adjustment of the elastic components, it achieves close contact with the lining plate, avoids stress concentration, and enhances structural safety.
It achieves uniform load transfer on uneven lining plate surfaces, reduces construction difficulty and operational risks, improves structural safety and reliability, and avoids lining plate cracking and foundation instability.
Smart Images
Figure CN122106103A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of channel cofferdam technology, and in particular to an improved channel lining plate repair cofferdam base structure. Background Technology
[0002] In recent years, most newly constructed water diversion projects in China have adopted concrete-lined open channels. After years of operation, due to factors such as uneven settlement, frost heave, and high groundwater levels, the lining plates on the channel floor and slopes are prone to localized damage. When performing maintenance without interrupting water flow, cofferdams are needed to create a waterless working environment. For lining plate repair, various cofferdam structures have been developed, such as cross-section compensation steel cofferdams, hydraulically self-stabilizing underwater construction cofferdams, slope-supported gallery cofferdams, semi-submersible cofferdams, prefabricated gate cofferdams, and floating box lift gate steel cofferdams. Regardless of the structure used, the self-weight load and water pressure load of the cofferdam are transferred to the channel lining plates through its base.
[0003] Taking a large-scale water diversion project's main canal as an example, the designed water depth is 8m. The canal lining uses 8-10cm thick C20 plain concrete slabs, divided into 4m×4m sections. Under normal water conveyance conditions, the water pressure on the upper surface of the lining slab is 80kPa, and the design value of the canal soil bearing capacity is 130-150kPa. When repairing or replacing the lining slab, the width of the cofferdam along the water flow direction must be at least 4m, and the average pressure of the cofferdam base on the lining slab should be less than 150kPa to avoid cracking of the lining slab or instability of the underlying soil. Theoretically, as long as the contact area between the cofferdam base steel plate and the lining slab is sufficient, pressure can be transmitted evenly. However, most existing concrete lining slabs are cast in place, with local protrusions or depressions on the surface, and the unevenness varies greatly, making it difficult to quantify and calculate the actual local stress on the lining slab. Although the specifications require that the unevenness of the lining slab within a 2m range be less than 2cm, the surface flatness of the two differs significantly from that of the steel plate. This can lead to situations where the protruding parts of the lining slab bear a large load, while the recessed parts bear a small load or even no load. In such cases, if the average pressure design of the cofferdam base is too low, the base size will be too large, increasing the structural self-weight and investment; if the design value is close to 150kPa, the average pressure on the protruding parts of the lining slab is likely to exceed 150kPa, posing a risk of damage.
[0004] To address the aforementioned issues, a patent (ZL202420146789.0) discloses a load transfer structure for a pre-stressed water bladder at the base of a cofferdam for channel repair. This structure divides the bottom of the cofferdam into several pressure zones, installs sealed water bladders, calculates preset pressure values for each zone based on the cofferdam's self-weight and water load, injects water using a booster pump, and controls the water pressure using a water pressure sensor. The isobaric properties inside the water bladder ensure uniform pressure on the outer surface, thus achieving a uniform surface load. However, in practical applications, this structure has been found to have the following shortcomings: the fully sealed bladder structure has high manufacturing costs; the method of using rubber plates to fix the water bladder around its perimeter makes the construction process of achieving complete sealing difficult; the cofferdam's operation and repair cycle is long, requiring continuous water replenishment and pressure maintenance, posing a high risk of pressure maintenance during night shifts; simultaneously, the friction between the rubber surface of the water bladder and the soil surface of the lining plate is necessary to maintain the cofferdam's stability, subjecting the rubber to significant in-plane tension, requiring high rubber strength and high clamping force at the pressure plate, and making it prone to leakage points after tension.
[0005] It is evident that the existing cofferdam base structure still has shortcomings in adapting to uneven concrete lining slabs, achieving uniform load transfer, and reducing construction difficulty and operational risks, and it is necessary to propose further improvement schemes. Summary of the Invention
[0006] To address the above problems, this invention provides an improved structure for repairing cofferdam bases with channel lining plates, specifically employing the following technical solutions: The improved channel lining plate repair cofferdam base structure of this invention is suitable for U-shaped inverted cofferdams divided into multiple segments along the channel slope. Both the inner and outer sides of the left and right bases of the cofferdam are provided with water-stopping structures connected to the base steel plate. Elastic supports are provided in the area between the water-stopping structures. Multiple elastic supports are provided, each including a guide bearing mounted on the base steel plate. A plunger rod penetrating the base steel plate is mounted on the guide bearing. A first limiting member is provided at the end of the plunger rod above the base steel plate, and a second limiting member is provided at the end of the plunger rod below the base steel plate. An elastic element is sleeved on the plunger rod between the base steel plate and the second limiting member. The bottom of the plunger rod is connected to the ball head of a spherical bearing. An anti-slip pad for pressing against the lining plate is provided on the base of the spherical bearing. The elastic supports are equally spaced, with a spacing L between adjacent elastic supports. <R 底座 +2n 剪 , where R 底座 n is the diameter of the base of the spherical bearing. 剪 The distance by which the load of the cofferdam spreads outward along the edge of the base of the spherical bearing; the elastic supports are grouped according to the cofferdam segments, and the spherical bearings and elastic components of the elastic supports in the same group are selected according to the same parameters, and the maximum load difference of the elastic supports in the same group is less than the shear resistance allowable value of the lining plate.
[0007] This invention employs a grouped system of elastic supports, consisting of plunger rods, elastic elements, and ball-joint bases, based on the stress magnitude of different sections of the cofferdam. Regardless of whether the lining plate is horizontal or not, the small area of the ball-joint base allows for adaptive and tight contact with the lining plate surface. When the lining plate is uneven, the absolute height of the contact points between the plunger rods and the lining plate varies. The cofferdam's self-weight and external water load act on the top of the elastic elements, compressing the elastic elements outside each plunger rod to different lengths. The sum of the loads on all elastic elements equals the total axial load of the cofferdam base. Because the elastic element design considers the elastic coefficient, the load on elastic elements with different compression lengths can be accurately calculated. When the difference in the compression length of the elastic elements is 2-3 cm, the load difference ensures that the shear force transmitted from the base to the lining plate does not exceed the shear resistance of the lining plate, thus ensuring the structural safety at the contact point between the cofferdam base and the lining plate. Compared to water-bag structures, while this invention does not achieve a uniform surface load structure, its design is simple to construct, easy to implement, and adaptable to lining plates with varying flatness. This avoids cumbersome adjustment operations, mitigates the risk of pressure loss, and demonstrates significant effectiveness. Furthermore, the ball-joint base connected to the plunger rod has an anti-slip pad at its lower part, providing sufficient radial anti-slip support to maintain the stability of the cofferdam. This avoids the risk of cofferdam instability caused by the failure of the water-bag under in-plane frictional tension, as seen in water-bag structures. Therefore, this invention significantly improves safety and reliability compared to water-bag load transfer structures.
[0008] Preferably, the minimum axial load F of the spherical bearing amin =2×F n / m, where F n The total pressure transmitted from the cofferdam segment containing the spherical bearing to the lining plate is denoted by , where m is the total number of elastic supports in the cofferdam segment; the minimum radial load F of the spherical bearing is denoted by . rmin =μ×F amin , where μ is the coefficient of friction between the base of the spherical bearing and the lining plate.
[0009] Preferably, the minimum axial load N of the plunger rod amin =L×L×f a Where L is the distance between adjacent elastic supports, f a Design bearing capacity for the channel foundation; minimum radial bearing capacity N of the plunger rod. rmin =μ×N amin , where μ is the coefficient of friction between the base of the spherical bearing and the lining plate.
[0010] Preferably, the maximum diameter of the base of the spherical bearing is 15cm.
[0011] Preferably, the guide bearing is fixed to the side of the base steel plate away from the lining plate by a bearing support, and the central axis of the guide bearing is perpendicular to the base steel plate.
[0012] This invention utilizes the frame structure of the cofferdam support frame to place the bearing support on the side of the base steel plate away from the lining plate. This not only effectively utilizes the space of the support frame, but also increases the effective length of the plunger rod's axial movement under the condition of limited space. The guide bearing is set perpendicular to the base steel plate, which can reduce the phenomenon of axial movement jamming of the plunger rod and ensure that it can move smoothly along the vertical direction of the base steel plate.
[0013] Preferably, the plunger rod is a hollow rod structure, and the outer wall of the plunger rod is clearance-fitted with the inner ring of the guide bearing; the first limiting member is a transverse insert or a shaft elastic retaining ring disposed at the top of the plunger rod, and the second limiting member is a sealing plug disposed at the bottom of the plunger rod, the sealing plug having a flange with an outer diameter larger than the outer diameter of the plunger rod and the elastic member.
[0014] In addition to being entirely hollow rod-shaped, the plunger rod in this invention can also be a structure with a solid upper rod and a hollow lower rod, which is beneficial for the installation of the second bottom limiting member.
[0015] Preferably, the elastic element is a cylindrical helical compression spring, the inner diameter of which is adapted to the outer diameter of the plunger rod, and when there are multiple elastic supports, the free length of each cylindrical helical compression spring is set to be equal.
[0016] Typically, the outer edge of the steel plate of the cofferdam base is equipped with a water-stopping structure. Therefore, using elastic elements with equal free lengths is more advantageous for creating a dry working environment for the cofferdam. At the same time, since the lining plate has different pressure at different water depths, the material of the spring wire used to prepare each cylindrical helical compression spring, as well as the compression performance of each cylindrical helical compression spring, should be specifically set according to the axial bearing capacity of the elastic support.
[0017] Preferably, the anti-slip pad is a nylon pad or rubber pad with anti-slip texture, and the anti-slip pad is the same size as the bottom surface of the spherical bearing base, while the bottom surface area of the spherical bearing base is larger than the cross-section of the ball head mounting end of the base.
[0018] The aforementioned anti-slip pads are attached to the bottom surface of the spherical bearing base. The bottom of the pads has a textured surface, which increases the coefficient of friction and thus increases the frictional force. Furthermore, the spherical bearing base adopts a variable diameter structure, which further increases the frictional force by increasing the area, thus preventing the cofferdam from sliding along the canal slope.
[0019] This invention is suitable for multi-segment cofferdams installed along the channel slope. It employs a grouped arrangement of multiple elastic supports to adjust the contact pressure between each cofferdam segment and the channel lining plate at multiple points. This ensures that the self-weight load and water load of the cofferdam are evenly distributed to the lining plate, preventing local pressure concentration and cracking caused by uneven surface of the lining plate. The deformation of the elastic element adjusts the effective length of the plunger rod, and the spherical bearing base adapts to the uneven lining plate surface through self-adjustment, preventing the local pressure at the cofferdam base from exceeding the bearing capacity of the channel foundation and ensuring the safety of the original structure when repairing the channel lining plate. When the cofferdam forms a dry environment on the channel slope, the water pressure along the channel slope will generate a force that pushes the cofferdam upward. The plunger rod forms a rigid shear-resistant structure with the lining plate through the anti-slip pad, effectively preventing the cofferdam from sliding along the channel slope. The invention has a simple structure, is easy to manufacture and install. When the cofferdam is in place, the elastic support can achieve self-adjustment and adaptation with the channel lining plate. During the use of the cofferdam, no manual adjustment and maintenance are required, which is safe, reliable and saves manpower and material resources. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure of the present invention.
[0021] Figure 2 yes Figure 1 Enlarged view of part A in the image.
[0022] Figure 3 yes Figure 2 A schematic diagram of the structure of a medium-elastic support.
[0023] Figure 4 yes Figure 1 A schematic diagram showing the distribution of the medium elastic supports on each cofferdam segment. Detailed Implementation
[0024] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific working processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.
[0025] Example 1: like Figure 1As shown, a U-shaped inverted cofferdam 1 has an external width of 13m and an internal net width of 9m. The base steel plates 2 on both sides are 2m wide. The cofferdam is designed for a water depth of 7m. When repairing the lining slab 3 with a 1:2 channel slope, the total length of the cofferdam along the channel slope is approximately 18m. Taking into account factors such as transportation, installation, and water pressure at the bottom of the cofferdam, the cofferdam 1 is divided into 3 2m segments and 4 3m segments along the channel slope from bottom to top. Under the action of external channel water load, the cofferdam undergoes bending deformation, especially in the segments in deep water. Under the action of bending moment, the inner side of the base steel plate 2 is compressed, and the outer side is upturned, forming a height difference deformation of about 2mm between the inner and outer sides. At the same time, errors or unevenness will exist in the processing and manufacturing process of the steel structure cofferdam and the pouring process of the channel bottom lining slab. If the base steel plate 2 of the cofferdam is in direct contact with the lining slab 3, there will inevitably be a state of local contact and local non-contact, and stress concentration will form at the contact points. After stress concentration, the plain concrete lining slab 3, 8-10 cm thick, is at risk of cracking, or the bearing capacity of the local foundation 4 may be insufficient after stress concentration, leading to foundation 4 depression and subsequent cracking of the lining slab 3. To avoid these situations, the base structure of the cofferdam 1 is repaired using the improved channel lining slab described in this invention.
[0026] like Figure 1-4 As shown, the cofferdam 1 includes a water-stopping structure 5 and elastic supports 6 installed on its base. The water-stopping structure 5 is installed on the inner and outer sides of the left and right base steel plates 2, and the elastic supports 6 are installed between the water-stopping structures 5. There are multiple elastic supports 6, which are evenly spaced on the base steel plates 2 and are grouped according to the segmentation of the cofferdam 1.
[0027] Each elastic support 6 includes a guide bearing 61 mounted on the base steel plate 2. A plunger rod 62 is mounted on the guide bearing 61 and penetrates the base steel plate 2. A first limiting member 63 is mounted on the upper end of the plunger rod 62, and a second limiting member 64 is mounted on the lower end of the plunger rod 62. An elastic member (usually a cylindrical helical compression spring 65) is sleeved on the plunger rod 62 between the base steel plate 2 and the second limiting member 64. The bottom of the plunger rod 62 is connected to the ball head 661 of the spherical bearing 66. An anti-slip pad 67 for pressing against the lining plate 3 is mounted on the base 662 of the spherical bearing 66.
[0028] Preferably, the guide bearing 61 is fixed to the side of the base steel plate 2 away from the lining plate 3 by a bearing support 611, and the central axis of the guide bearing 61 is perpendicular to the base steel plate 2. The plunger rod 62 can be a hollow rod or a [other type of rod]. Figure 2 , 3The hollow rod-shaped structure is shown. The outer wall of the plunger rod 62 is clearance-fitted with the inner ring of the guide bearing 61, allowing the plunger rod 62 to move axially along the guide bearing 61. The first limiting member 63 can be a transverse insert or a shaft elastic retaining ring installed at the top of the plunger rod 62, and the second limiting member 64 is a sealing plug located at the bottom of the plunger rod 62, with a flange having an outer diameter larger than the outer diameter of the plunger rod and the outer diameter of the compression spring 65. The inner diameter of the compression spring 65 is adapted to the outer diameter of the plunger rod, and all compression springs 65 have equal free lengths. The anti-slip pad 67 is mostly made of nylon or rubber with anti-slip texture, and the anti-slip pad 38 is the same size as the bottom surface of the base 662 of the spherical bearing 66, while the bottom surface area of the base 662 of the spherical bearing 66 is larger than the cross-section of the ball end of the base 662. Typically, the maximum diameter of the base 662 of the spherical bearing 66 is 15 cm.
[0029] Example 2: The present invention determines the spacing and number of elastic supports according to the following scheme.
[0030] 1. Determine the spacing of the elastic supports. The spherical bearing 66 connected to the plunger rod 62 at the bottom of the cofferdam 1 is proposed to use a circular base 662 with a diameter of 15cm. The load of the base steel plate 2 to the plunger rod 62 base (i.e., the circular base 662) is transferred to the lining plate 3 through the compression spring 65. The destructive force of this load on the lining plate 3 is shear force, which diffuses at 45° towards the lower surface of the lining plate 3. Since the thickness of the lining plate 3 is 10cm, the influence range of this shear force on the lower surface of the lining plate 3 is a circle with a diameter of 35cm that contacts the channel foundation 4. In order to make the shear force acting on the lower surface of the lining plate 3 of each adjacent elastic support 6 overlap, the spacing between adjacent elastic supports 6 should be less than 35cm, that is: Spacing L between adjacent elastic supports <R 底座 +2n 剪 , Among them, R 底座 n is the diameter of the base of the spherical bearing. 剪 This is the distance the cofferdam load spreads outward along the edge of the spherical bearing base; In this embodiment, the distance between adjacent elastic supports 6 is 0.34m.
[0031] 2. Determine the number of elastic supports. The base steel plates 2 of the first to third sections of the cofferdam are all 2m×2m in size, so each section is equipped with 36 elastic supports 6; the base steel plates 2 of the fourth to seventh sections are all 3m×2m in size, so each section is equipped with 54 elastic supports 6.
[0032] Example 3: The present invention selects compression springs according to the following scheme.
[0033] In this invention, the compression springs 65 in the same group on the same base steel plate 2 are of the same specification, and to ensure a flat bottom for the cofferdam 1, the free lengths of all compression springs 65 are equal. Because the weight of the cofferdam 1 and the external load are automatically distributed to the compression springs 65 on the base, and due to the different heights of the lining plates 3, even compression springs in the same group will not have completely identical compression amounts. To avoid damage to the compression springs 65 caused by the above situation, the wire diameter, spring mean diameter, free length, and compression length should be preferably selected. All of these parameters should be determined based on the axial bearing capacity of the elastic support 6.
[0034] In this embodiment, the design bearing capacity of the channel foundation 4 is 150 kPa. After the cofferdam 1 forms an average load at the bottom of the foundation at a water depth of 7 m, the approximate stresses from bottom to top are 130 kPa, 120 kPa, 100 kPa, 80 kPa, 60 kPa, 45 kPa, and 30 kPa, respectively, and the compressive stress is not greater than 150 kPa.
[0035] The total pressure transmitted to the lining plate from the first section of the cofferdam is 2 × 2 × 130 = 520 kN, with 36 elastic supports and an average support reaction force of 14.4 kN per support. The total pressure transmitted to the lining plate from the second section of the cofferdam is 2 × 2 × 120 = 480 kN, with 36 elastic supports and an average support reaction force of 13.3 kN per support. The total pressure transmitted to the lining plate from the third section of the cofferdam is 2 × 2 × 100 = 400 kN, with 36 elastic supports and an average support reaction force of 11.1 kN per support. The total pressure transmitted to the lining plate from the fourth section of the cofferdam is 3 × 2 × 80 = 480 kN, with 54 elastic supports and an average support reaction force of 8.89 kN per support. The total pressure transmitted from the 5th segment of the cofferdam to the lining plate is 3 × 2 × 60 = 360 kN. With 54 elastic supports, the average support reaction force of each support is 6.67 kN. The total pressure transmitted from the 6th segment of the cofferdam to the lining plate is 3 × 2 × 45 = 360 kN. With 54 elastic supports, the average support reaction force of each support is 5 kN. The total pressure transmitted from the 7th segment of the cofferdam to the lining plate is 3 × 2 × 30 = 360 kN. With 54 elastic supports, the average support reaction force of each support is 3.3 kN.
[0036] Since the unevenness of the lining plate 3 is 2cm, the maximum and minimum compression lengths of the compression spring 65 should differ by a maximum of 2cm. Considering the height of the water-stopping structures on the inner and outer sides of the cofferdam 1, the initial length of the compression spring 65 is proposed to be 120mm, with an average compression length of 90mm. Different specifications of springs are selected according to the sections of the cofferdam. The springs are made of stainless steel, model SUS304-WPB, with a transverse elastic modulus G of 7000Kg / mm². 2 Maximum stress S max =76Pa.
[0037] The average axial bearing capacity of the elastic support 6 on the base of the first section of the cofferdam is 14.4 kN. The selected spring wire has a diameter of 16 mm, a mean diameter of 92 mm, an original length of 120 mm, a pitch of 48 mm, 3.5 coils, a minimum spring length of 72 mm, and a spring constant of 49095 g / mm². When the spring is compressed to a length of 80 mm, the force is 19.2 kN; when the spring is compressed to a length of 90 mm, the force is 14.4 kN; and when the spring is compressed to a length of 100 mm, the force is 9.6 kN. The spring meets the deformation requirements. Since the spacing of the elastic supports 6 is 0.34m, the height difference within a 2m range is approximately 2cm, and the maximum height difference between adjacent supports is approximately 1cm. The vertical load difference is 19.2-14.4=4.8kN or 14.4-9.6=4.8kN, so the maximum difference is 19.2-14.4=4.8kN. If the lining plate is at its thinnest point of 8cm, and we calculate 1 / 4 of the perimeter, then the vertical punching shear stress of the lining plate is... , The lining slab is made of C20 concrete with an axial compressive strength of 9.6 N / mm². 2 .
[0038] It can be seen that the maximum load difference between the elastic supports in the same group is less than the shear resistance of the lining plate, and the shear force difference between two adjacent elastic supports will not cause the lining plate to be crushed.
[0039] The average axial bearing capacity of the elastic support 6 on the base of the second section of the cofferdam is 13.3 kN. The selected spring wire has a diameter of 16 mm, a mean diameter of 94 mm, an initial length of 120 mm, a pitch of 48 mm, 3.5 coils, a minimum spring length of 72 mm, and a spring constant of 46027 g / mm². When the spring is compressed to a length of 80 mm, the force is 18 kN; when the spring is compressed to a length of 90 mm, the force is 13.5 kN; and when the spring is compressed to a length of 100 mm, the force is 9 kN. The spring meets the deformation requirements.
[0040] The average axial bearing capacity of the elastic support 6 on the base of the third section of the cofferdam is 11.1 kN. The selected spring wire has a diameter of 16 mm, a mean diameter of 100 mm, an initial length of 120 mm, a pitch of 48 mm, 3.5 coils, a minimum spring length of 72 mm, and a spring constant of 38229 g / mm². When the spring is compressed to a length of 80 mm, the force is 15 kN; when the spring is compressed to a length of 90 mm, the force is 11.25 kN; and when the spring is compressed to a length of 100 mm, the force is 7.5 kN. The spring meets the deformation requirements.
[0041] The average axial bearing capacity of the elastic support 6 on the base of the fourth section of the cofferdam is 8.89 kN. The selected spring wire has a diameter of 14 mm, a mean diameter of 82 mm, an original length of 120 mm, a pitch of 39 mm, 4 coils, a minimum spring length of 70 mm, and a spring constant of 32826 g / mm². When the spring is compressed to a length of 80 mm, the force is 11.9 kN; when the spring is compressed to a length of 90 mm, the force is 8.95 kN; and when the spring is compressed to a length of 100 mm, the force is 6.0 kN. The spring meets the deformation requirements.
[0042] The average axial bearing capacity of the elastic support 6 at the bottom of the fifth section of the cofferdam is 6.67 kN. The selected spring wire has a diameter of 14 mm, a mean diameter of 90 mm, an original length of 120 mm, a pitch of 39 mm, 4 coils, a minimum spring length of 70 mm, and a spring constant of 18997 g / mm². When the spring is compressed to a length of 80 mm, the force is 9.0 kN; when the spring is compressed to a length of 90 mm, the force is 6.75 kN; and when the spring is compressed to a length of 100 mm, the force is 4.5 kN. The spring meets the deformation requirements.
[0043] The average axial bearing capacity of the elastic support on the base of the sixth section of the cofferdam is 5kN. The selected spring wire has a diameter of 14mm, a mean diameter of 100mm, an original length of 120mm, a pitch of 39mm, 4 coils, a minimum spring length of 70mm, and a spring constant of 16807g / mm². When the spring is compressed to a length of 80mm, the force is 6.6kN; when the spring is compressed to a length of 90mm, the force is 5kN; and when the spring is compressed to a length of 100mm, the force is 3.4kN. The spring meets the deformation requirements.
[0044] The average axial bearing capacity of the elastic support 6 on the base of the 7th segment cofferdam is 3.3 kN. The selected spring wire has a diameter of 14 mm, a mean diameter of 100 mm, an initial length of 120 mm, a pitch of 26 mm, 4.6 coils, a minimum spring length of 78.4 mm, and a spring constant of 11205 g / mm². When the spring is compressed to a length of 80 mm, the force is 5.0 kN; when the spring is compressed to a length of 90 mm, the force is 3.7 kN; and when the spring is compressed to a length of 100 mm, the force is 2.5 kN. The spring meets the deformation requirements.
[0045] Example 4: The present invention selects the plunger rod, guide bearing and spherical bearing according to the following scheme.
[0046] Under water pressure, the compression spring 65 automatically distributes the axial load to the plunger rod 62 to the second limiting member 64. The second limiting member 64 transmits the load to the base 662 through the spherical bearing 66, and the base 662 transmits the load to the lining plate 3. Furthermore, there is friction between the anti-slip pad 67 and the lining plate 3.
[0047] 1. Plunger rod selection Minimum axial load N of a single plunger rod 62 amin =L×L×f a Where L is the distance between adjacent elastic supports 6, and f a Design bearing capacity for channel foundation 4; minimum radial bearing capacity N of a single plunger rod 62. rmin =μ×N amin , where μ is the coefficient of friction between the base of the spherical bearing and the lining plate.
[0048] In this embodiment, N amin =0.34×0.34×150=17.34kN, N rmin =0.3×17.34=5.2kN, then the plunger rod should be a metal rod with an axial bearing capacity of 18kN and a radial bearing capacity of 5.5kN.
[0049] 2. Selection of Guide Bearings The guide bearing 61 ensures that the plunger rod 62 can slide axially, preventing jamming due to excessive hole clearance. Simultaneously, the clearance fit allows radial water load to be applied to the plunger rod 62. The maximum load on the guide bearing 61 is the product of the axial pressure on the plunger rod 62 and the coefficient of friction between the anti-slip pad 67 and the lining plate.
[0050] In this embodiment, the axial bearing capacity of the selected plunger rod 62 is 18kN, and the coefficient of friction between the anti-slip pad 67 and the lining plate is 0.3. Therefore, the maximum radial load of the guide bearing 61 is 5.4kN. The length of the guide bearing 61 can be determined by combining its inner diameter and its maximum radial load, or a suitable model can be selected from standard products based on the inner diameter of the guide bearing 61.
[0051] 3. Spherical bearing selection The spherical bearing 66 consists of a ball head 661 with a threaded short post and a base 662. The appropriate size of the spherical bearing 66 is selected based on the axial and radial loads of the plunger rod 62. The ball head 661 has a short thread and is used to connect to the plunger rod 62 (in this embodiment, the ball head 661 is connected to the second limiting member 64, which serves as a sealing plug). The base 662 is slidably connected to the ball head 661, and its bottom surface is a circular planar structure with a diameter of 15cm. Of course, the bottom surface of the base 662 can also be square, etc.
[0052] Minimum axial load F of spherical bearing 66amin =2×F n / m, where F n The total pressure transmitted from the cofferdam segment containing the spherical bearing to the lining plate is denoted by , where m is the total number of elastic supports in the cofferdam segment; the minimum radial load F of the spherical bearing is denoted by . rmin =μ×F amin , where μ is the coefficient of friction between the base of the spherical bearing and the lining plate.
[0053] The lining plate near the bottom of the water experiences greater pressure; therefore, the design load of the spherical bearing 66 in the first section of the cofferdam should be greater than that in other sections. However, for ease of procurement and maintenance, all spherical bearings 66 are selected of the same model, and their design load is calculated based on the total pressure transmitted from the first cofferdam section to the lining plate. According to the above formula, F amin =2×(2×2×130) / 36=28.8 kN, F rmin =0.3×28.8=8.64kN. Therefore, when selecting a bearing, both the load-bearing capacity and economy of the spherical bearing 66 should be considered.
[0054] The connection between the aforementioned spherical bearing 66 and the plunger rod 62 includes, but is not limited to, a threaded connection. This connection pair shall ensure a compressive strength of not less than 28.8 kN, a shear strength of not less than 8.64 kN, and a bending moment of not less than the product of the maximum shear force and the maximum stroke of the telescopic rod. At the same time, it shall meet the stability requirements of the ball-end short rod.
[0055] It should be noted that in the description of this invention, terms such as "front," "rear," "left," "right," "vertical," "horizontal," "inner," and "outer" indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
Claims
1. An improved structure for repairing a cofferdam base using channel lining plates, suitable for U-shaped inverted cofferdams divided into multiple segments along the channel slope, characterized in that: The cofferdam has water-stopping structures connected to the base steel plates on both the inner and outer sides of its left and right bases, and elastic supports are provided in the area between the water-stopping structures. The elastic support comprises multiple supports, each of which includes a guide bearing mounted on the base steel plate. A plunger rod penetrating the base steel plate is mounted on the guide bearing. A first limiting member is mounted on the upper end of the plunger rod above the base steel plate, and a second limiting member is mounted on the lower end of the plunger rod below the base steel plate. An elastic member is sleeved on the plunger rod between the base steel plate and the second limiting member. The bottom of the plunger rod is connected to the ball head of a spherical bearing. An anti-slip pad for pressing against the lining plate is mounted on the base of the spherical bearing. The elastic supports are spaced equally, and the distance between adjacent elastic supports L < R. 底座 +2n 剪 , where R 底座 n is the diameter of the base of the spherical bearing. 剪 This is the distance the cofferdam load spreads outward along the edge of the spherical bearing base; The elastic supports are grouped according to the cofferdam sections. The spherical bearings and elastic components of the elastic supports in the same group are selected according to the same parameters, and the maximum load difference of the elastic supports in the same group is less than the shear resistance allowable value of the lining plate.
2. The improved channel lining plate repair cofferdam base structure according to claim 1, characterized in that: The minimum axial load F of the spherical bearing amin =2×F n / m, where F n The total pressure transmitted from the cofferdam segment containing the spherical bearing to the lining plate is denoted by , where m is the total number of elastic supports in the cofferdam segment; the minimum radial load F of the spherical bearing is denoted by . rmin =μ×F amin , where μ is the coefficient of friction between the base of the spherical bearing and the lining plate.
3. The improved channel lining plate repair cofferdam base structure according to claim 1, characterized in that: The minimum axial load N of the plunger rod amin =L×L×f a Where L is the distance between adjacent elastic supports, f a Design bearing capacity for the channel foundation; minimum radial bearing capacity N of the plunger rod. rmin =μ×N amin , where μ is the coefficient of friction between the base of the spherical bearing and the lining plate.
4. The improved channel lining plate repair cofferdam base structure according to claim 1, characterized in that: The maximum diameter of the base of the spherical bearing is 15cm.
5. The improved channel lining plate repair cofferdam base structure according to claim 1, characterized in that: The guide bearing is fixed to the side of the base steel plate away from the lining plate by a bearing support, and the central axis of the guide bearing is set perpendicular to the base steel plate.
6. The improved channel lining plate repair cofferdam base structure according to claim 1, characterized in that: The plunger rod is a hollow rod-shaped structure, and the outer wall of the plunger rod is in clearance fit with the inner ring of the guide bearing; the first limiting member is a transverse insert or shaft elastic retaining ring set at the top of the plunger rod, and the second limiting member is a sealing plug set at the bottom of the plunger rod, the sealing plug having a flange with an outer diameter larger than the outer diameter of the plunger rod and the elastic member.
7. The improved channel lining plate repair cofferdam base structure according to claim 1, characterized in that: The elastic element is a cylindrical helical compression spring. The inner diameter of the cylindrical helical compression spring is adapted to the outer diameter of the plunger rod. When there are multiple elastic supports, the free length of each cylindrical helical compression spring is set to be equal.
8. The improved channel lining plate repair cofferdam base structure according to claim 1, characterized in that: The anti-slip pad is made of nylon or rubber with anti-slip texture, and the anti-slip pad is the same size as the bottom surface of the spherical bearing base, while the bottom surface area of the spherical bearing base is larger than the cross-section of the ball head mounting end of the base.