Concrete bottom plate water stop method based on stress optimization and deformation control of construction joint

Abstract

The present application belongs to the technical field of concrete construction, and particularly relates to a concrete bottom plate water stop method based on stress optimization and deformation control of construction joints, comprising the following steps: step S1, performing cast-in-place pile measurement and lofting at both ends of the construction joint; step S2, after the cast-in-place pile construction is completed and reaches the design strength, chiseling the pile head of the cast-in-place pile, and excavating between the two cast-in-place piles to form a foundation pit groove corresponding to the construction joint; step S3, pouring concrete with the foundation pit groove as a pouring formwork, and the upper surface elevation of the support beam and the lower surface elevation of the concrete bottom plate being at the same level; and step S4, pouring the concrete bottom plate. Through the "pile-beam" rigid support system, the differential settlement between adjacent bottom plates is actively constrained and eliminated, the core problem of shear damage of the water stop in the traditional technology caused by the settlement difference is solved from the root, and a leap from "passive deformation adaptation" to "active deformation control" is realized.

Description

Technical Field

[0001] This invention belongs to the technical field of concrete construction, specifically relating to a method for water-stopping concrete slabs based on stress optimization and deformation control of construction joints. Background Technology

[0002] In large-scale water conservancy projects, structures such as navigation walls, dams, and locks are often composed of multiple large-volume concrete slabs connected together. Due to phased construction, uneven soil conditions, and differences in superstructure loads, uneven settlement between adjacent slabs is unavoidable. This differential deformation is transmitted through construction joints, creating complex tensile and shear stress concentrations on the sealing system (such as copper sheet waterstops) and surrounding concrete. This ultimately leads to concrete cracking, debonding of the waterstops from the concrete, and leakage, threatening structural safety and durability. To address this problem, existing technologies mainly employ two types of solutions: The first is foundation reinforcement treatment, which improves the bearing capacity of the foundation by means of grouting, mixing pile reinforcement and other methods, in an attempt to reduce settlement differences from the source; Secondly, the water-stopping structure is optimized by using flexible composite water-stopping materials, optimizing the structure of the water-stopping sheets, or improving the concrete around the water-stopping area, in an attempt to improve the water-stopping system's adaptability to deformation and reduce local stress. However, the existing technical solutions mentioned above have the following insurmountable drawbacks: (1) The cost of full-area foundation reinforcement treatment is high and the effect is limited: the construction cycle of foundation reinforcement measures such as grouting and mixing piles is long and the cost is high. For complex geological conditions such as soft soil foundation, it is difficult to completely eliminate the uneven settlement between adjacent bottom plates. Differential deformation will remain, causing the water-stopping system to bear residual shear stress and tensile stress, and the risk of settlement difference damage cannot be eliminated from the root.

[0003] (2) Waterstop structure optimization is a passive protection and has an upper limit to its adaptability: Traditional waterstop structure optimization can only passively adapt to settlement deformation by improving the deformation capacity of waterstop materials. It cannot actively eliminate the deformation itself. When the settlement difference exceeds the limit deformation capacity of the waterstop material, waterstop failure will still occur.

[0004] (3) The sealing material and the 2cm thick polyethylene closed-cell foam board caulking inside the joint will age over time, and the material's ultimate deformation capacity will also decline significantly. It is only a matter of time before the sealing fails and leakage occurs.

[0005] (4) Traditional rigid constraint schemes (such as support beams) are complex to construct and costly: Some technologies attempt to set up reinforced concrete support beams below the joints to constrain settlement, but traditional schemes require over-excavation of the original soil before setting up formwork, which has problems such as high formwork cost, complicated demolition process, large working space requirements, and low construction efficiency. In addition, it causes a large disturbance to the original soil under the bottom plate, making it difficult to promote and apply.

[0006] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a method for water-stopping concrete slabs based on stress optimization and deformation control of construction joints.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A method for waterproofing concrete slabs based on construction joint stress optimization and deformation control includes the following steps: Step S1: Measure and set out the cast-in-place piles at both ends of the construction joint; Step S2: After the cast-in-place piles are constructed and reach the design strength, the pile heads are removed, and a foundation pit is excavated between the two cast-in-place piles to form a corresponding construction joint. Step S3: Concrete is poured using the foundation pit as a pouring template to form a support beam. The elevation of the upper surface of the support beam is at the same level as the elevation of the lower surface of the concrete base plate. Step S4: Pour the concrete base slab, so that the construction joint of the concrete base slab extends along the centerline of the supporting beam.

[0009] Preferably, the cross-section of the support beam is an inverted trapezoid, and the length of the base of the trapezoid is greater than the diameter of the cast-in-place pile.

[0010] Preferably, the slope corresponding to the waist of the trapezoid is 30~60°.

[0011] Preferably, the upper edge of the support beam extends to both sides of the construction joint to form an extension of the corresponding bottom sealing concrete.

[0012] Preferably, the support beam has a steel reinforcement cage inside.

[0013] Preferably, the pile head reinforcement of the cast-in-place pile extends into the reinforcement cage and is tied together with the reinforcement cage.

[0014] Preferably, in step S4, before pouring the concrete base slab, the sealing concrete under the concrete base slab is poured first, so that the sealing concrete and the supporting beam are connected as a whole.

[0015] Preferably, a waterstop plate extending along the length of the construction joint is provided in the middle of the construction joint.

[0016] Preferably, the length of the cast-in-place pile extending into the bearing layer is not less than 1.5 times its diameter.

[0017] Beneficial effects: (1) Through the "pile-beam" rigid support system, differential settlement between adjacent bottom plates is actively constrained and eliminated, fundamentally solving the core problem of differential settlement leading to shear failure of waterstop in traditional technology. Compared with large-area foundation reinforcement, this scheme is more precise in its target and more reliable in its effect, realizing the leap from "passive adaptation to deformation" to "active control of deformation".

[0018] (2) The elimination of differential settlement changes the stress state of the construction joint to be dominated by negative bending moment, with tension at the bottom and compression at the top. Compared with the complex combination of tension and shear stress, this single stress mode greatly simplifies the stress environment of the water-stopping system and reduces the risk of concrete cracking and water-stop debonding.

[0019] (3) The use of trapezoidal soil molds to cast support beams completely eliminates the formwork erection and dismantling procedures and material costs required by traditional methods. It is particularly suitable for construction in narrow spaces under the base slab, solving the problem of formwork operation, resulting in high construction efficiency, short construction period, and significantly reduced cost.

[0020] (4) Since uneven settlement has been eliminated by the rigid support system, the foam board in the joints used in traditional designs to prevent differential settlement and concrete erosion is no longer necessary. This invention allows the elimination of foam boards at the joints, which not only saves foam board materials and installation labor, but also simplifies the construction joint structure and avoids subsequent problems caused by the aging and failure of foam boards.

[0021] (5) This construction process is highly compatible with conventional water conservancy engineering foundation slab construction procedures, requires no special large-scale equipment, and is easy to organize and implement on site. It is applicable to various hydraulic concrete structures with uneven settlement risks, such as navigation walls, dams, ship locks, and pumping stations, and has high application value. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 This is a schematic cross-sectional view of the long side waterstop structure of the concrete base plate in a specific embodiment of the present invention; Figure 2 This is a schematic cross-sectional view of the short-side water-stop structure of the concrete base plate in a specific embodiment of the present invention.

[0023] In the diagram: 1. Left base plate; 2. Right base plate; 3. Construction joint; 4. Cast-in-place pile; 5. Support beam; 6. Waterstop plate; 7. Sealing concrete. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0025] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0027] like Figure 1 and Figure 2 As shown, a concrete base slab water-stopping method based on stress optimization and deformation control of construction joint 3 includes the following steps: Step S1, according to the construction drawings of the concrete base slab, determine the location and length of construction joint 3, and then use a total station to accurately measure and lay out the two ends of construction joint 3, mark the center position of the cast-in-place pile 4, and ensure that the center line connecting the two cast-in-place piles 4 coincides with the center line of construction joint 3. The layout error is controlled within ±5mm to ensure the accuracy of subsequent construction.

[0028] Step S2: Construct the cast-in-place piles 4 according to the positions marked by the survey and layout. The cast-in-place piles 4 are bored cast-in-place piles 4. After the cast-in-place piles 4 are constructed, they are cured until they reach 80% of their design strength. The soil layer is first excavated to the bottom elevation of the support beam, and then the pile head of the cast-in-place pile 4 is removed. After the cast-in-place pile 4 is removed, the top elevation of the concrete of the cast-in-place pile 4 should be 5cm higher than the bottom elevation of the concrete of the support beam. Then, the foundation pit is excavated between the two cast-in-place piles 4. During the excavation process, the sidewalls of the foundation pit are compacted or shotcreted, and the loose soil and debris at the bottom of the foundation pit are cleaned to ensure that the bottom of the foundation pit is flat and compacted.

[0029] Step S3: Using the excavated foundation pit as a formwork, pour the support beam 5. The upper surface elevation of the support beam 5 is at the same level as the lower surface elevation of the concrete base slab. First, lay a 100mm plain concrete pad of the same grade as the support beam at the bottom of the foundation pit for leveling. Then, tie the reinforcing steel cage of the support beam 5, insert the pile head reinforcing steel of the cast-in-place pile 4 into the reinforcing steel cage, and fix it to the reinforcing steel cage by tying. The anchorage length of the top reinforcing steel of the cast-in-place pile 4 extending into the beam should not be less than 50cm to ensure that the beam and the cast-in-place pile 4 form an integral rigid load-bearing system. After the reinforcing steel cage is tied, pour the concrete. During the pouring process, use a vibrator to vibrate in layers to ensure compaction. After pouring, cure in time to finally form the support beam 5. Step S4: After the support beam 5 has cured to 80% of its design strength, pour the concrete base slab. After pouring, the construction joint 3 of the concrete base slab extends along the centerline of the support beam 5.

[0030] The rigid "pile-beam" support system formed by the supporting beam 5 and the two end piles 4 supports the ends of two adjacent bottom slabs on the left and right halves of the same rigid beam, fundamentally constraining the vertical relative displacement of the adjacent bottom slabs and actively eliminating the uneven settlement difference that would lead to waterstop failure. The elimination of the settlement difference fundamentally changes the stress state at construction joint 3, optimizing it from the most unfavorable state of shear and bidirectional tensile stress to a stress state under negative bending moment—that is, the concrete at the bottom of construction joint 3 is under tension, while only the top area is under compressive stress. This stress optimization greatly reduces the stress level and failure risk of the bottom slab waterstop 6 and its surrounding concrete.

[0031] In this embodiment, a waterstop 6 is provided along the length of the construction joint 3 in the middle. The waterstop 6 is made of copper, with a thickness of 1.5 mm and a width of 350 mm. The center line of the projection of the waterstop 6 coincides with the center line of the construction joint 3. The left and right ends of the waterstop 6 are respectively embedded in the left bottom plate 1 and the right bottom plate 2.

[0032] In an optional embodiment, the upper elevation of the support beam 5 is kept at the same level as the lower elevation of the concrete base slab. The cross-section of the support beam 5 is an inverted trapezoid, and the length of the base of the trapezoid is greater than the diameter of the cast-in-place pile 4. Preferably, the base of the trapezoid is 1.5 times the diameter of the cast-in-place pile 4, and the excavated soil wall is directly used as the casting template (soil mold), eliminating the traditional formwork process.

[0033] The slope corresponding to the waist of the trapezoid is 30~60°. The preferred slope corresponding to the waist of the trapezoid is 45°. Taking a pile diameter of 1 meter for the cast-in-place pile 4 as an example, the bottom width of the trench can be set to 1.5 meters to provide sufficient operating space for the binding of the beam reinforcement; the trench depth (i.e. the beam height) is set to 1 meter; the two sides of the trench are treated with a 1:1 slope to form a stable trapezoidal soil mold.

[0034] Furthermore, the upper edge of the support beam 5 extends to both sides of the construction joint 3 to form an extension of the corresponding bottom sealing concrete 7. The internal steel bars of the extension are tied together with the steel reinforcement skeleton of the support beam 5. Before pouring the concrete base slab in step S4, the bottom sealing concrete 7 under the concrete base slab is poured first. The thickness of the bottom sealing concrete is 100mm. Through pouring, the bottom sealing concrete 7 is connected to the support beam 5 as a whole, which serves as both the support beam 5 and the bottom sealing function.

[0035] Specifically, after the supporting beam 5 has cured to 80% of its design strength, the sealing concrete 7 under the two concrete base slabs will be poured. The sealing concrete 7 will be plain concrete of the same grade as the concrete base slabs. The base slab construction will proceed after the sealing concrete 7 has reached 80% of its design strength. After the concrete base slab is poured, it will be cured in a timely manner to ensure that the concrete base slab reaches its design strength.

[0036] Furthermore, the diameter and length of the cast-in-place pile 4 are determined according to the engineering geological conditions and bearing capacity requirements. During the construction of the cast-in-place pile 4, the disturbance to the original soil at the bottom of the base slab should be minimized. It is preferable that the length of the cast-in-place pile 4 extending into the bearing layer is not less than 1.5 times its diameter, so as to ensure that the vertical bearing capacity of a single pile can meet the load requirements of the adjacent base slab ends and provide a stable support for the subsequent support beam 5.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall be within the scope of protection of the pending claims of the present invention.

Claims

1. A method for waterproofing concrete slabs based on stress optimization and deformation control at construction joints, characterized in that, Includes the following steps: Step S1: Measure and set out the cast-in-place piles at both ends of the construction joint; Step S2: After the cast-in-place piles are constructed and reach the design strength, the pile heads are removed, and a foundation pit is excavated between the two cast-in-place piles to form a corresponding construction joint. Step S3: Concrete is poured using the foundation pit as a pouring template to form a support beam. The elevation of the upper surface of the support beam is at the same level as the elevation of the lower surface of the concrete base plate. Step S4: Pour the concrete base slab, so that the construction joint of the concrete base slab extends along the centerline of the supporting beam.

2. The method for water-stopping concrete slabs based on construction joint stress optimization and deformation control according to claim 1, characterized in that, The cross-section of the support beam is an inverted trapezoid, and the length of the base of the trapezoid is greater than the diameter of the cast-in-place pile.

3. The method for water-stopping concrete slabs based on construction joint stress optimization and deformation control according to claim 2, characterized in that, The slope of the waist of the trapezoid is 30° to 60°.

4. The method for water-stopping concrete slabs based on construction joint stress optimization and deformation control according to claim 1, characterized in that, The upper edge of the support beam extends to both sides of the construction joint to form the extension of the corresponding bottom sealing concrete.

5. The method for water-stopping concrete slabs based on construction joint stress optimization and deformation control according to claim 4, characterized in that, The supporting beam has a steel reinforcement cage inside.

6. The method for water-stopping concrete slabs based on construction joint stress optimization and deformation control according to claim 5, characterized in that, The reinforcing bars at the pile head of the cast-in-place pile extend into the reinforcing bar cage and are tied together with the reinforcing bar cage.

7. The method for water-stopping concrete slabs based on construction joint stress optimization and deformation control according to claim 5, characterized in that, In step S4, before pouring the concrete base slab, the sealing concrete under the concrete base slab is poured first, so that the sealing concrete is connected to the supporting beam as a whole.

8. The method for water-stopping concrete slabs based on construction joint stress optimization and deformation control according to claim 1, characterized in that, A waterstop plate extending along the length of the construction joint is provided in the middle of the joint.

9. The method for water-stopping concrete slabs based on construction joint stress optimization and deformation control according to claim 1, characterized in that, The length of the cast-in-place pile extending into the bearing stratum shall not be less than 1.5 times its diameter.

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