Method for applying in-pipe circumferential prestress in stages and layers

Abstract

The invention relates to a method for staged and layered implementation of in-pipe circumferential prestress. The method comprises the steps of staged implementation of target pressure, device arrangement, load application, glue pouring, dismantling and the like. The method provided by the invention can greatly reduce the rigidity and strength requirements of a counter-force device, and can greatly reduce the capability requirement of a loading device; and meanwhile, the strength requirement during form stripping is reduced, the curing waiting time of a single-layer adhesive is shortened, and the impact of single system conversion on the system is reduced.

Description

Technical Field

[0001] The present invention relates to a method for implementing circumferential prestress inside a pipe in stages and layers, belonging to the technical field of trenchless reinforcement engineering for high-pressure water transmission pipes. Background Technique

[0002] Currently, there are two common methods for reinforcing broken wires in PCCP pipes. One is to directly paste multiple layers of carbon fiber cloth, and the other is circumferential prestress reinforcement. Directly pasting multiple layers of carbon fiber cloth cannot make full use of the original concrete strength, stiffness, and the characteristics of high-strength carbon fiber cloth. At the same time, the large-area pasting of carbon cloth inside the pipe completely relies on manual glue brushing and pasting, resulting in low efficiency and unguaranteed quality. For circumferential prestress reinforcement, using a rigid steel ring as both a permanent structure and a temporary grouting formwork is a permanent-temporary combined design method. However, this requires a rigid steel ring for the structural system, causing a certain waste for general reinforcement working conditions with relatively low requirements, and it cannot be efficient in terms of time.

[0003] Through research, although the previous research on circumferential prestress reinforcement technology did not clearly define the high-strength material form as a plate, it can be a plate, a tendon, or a cloth. When using a plate, the number of wire bundles in the cross-section is large, and the prestress application load is large. The plate and the pipe are bonded through the interface. The fiber cloth is a cloth material woven from fiber ropes, which can penetrate the structural glue, and the integration degree and reliability between the cloth material and the pipe are high. When using a carbon plate for reinforcement, its width is 1 / 2 or 1 / 3 of the object to be reinforced, and the strength utilization ratio is small. When using a cloth material, due to its thinness and relatively few wire bundles, the strength utilization ratio is more reasonable, and the bonding area is large and the bonding force is higher.

[0004] The existing circumferential prestress technology inside the pipe has feasibility and reliability, but there are deficiencies in methods, theories, and process equipment in terms of equipment lightening, prestress loss caused by micro-cracks in the original pipe fittings, and reinforcement potential of cloth materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to overcome the shortcomings of the existing technology and provide a method for implementing circumferential prestress inside a pipe in stages and layers with a low single prestress level and relatively high prestress levels formed by multiple composites.

[0006] To solve the above technical problem, the technical solution proposed by the present invention is: a method for implementing circumferential prestress inside a pipe in stages and layers, including the following steps: (1) Divide the designed implementation target pressure of the construction target into several parts according to the requirements of the construction target; (2) Arrange the pressure-bearing steel cylinder at the construction target position, and evenly sleeve the sleeve-shaped composite high-strength cloth material on the outer surface of the pressure-bearing steel cylinder; (3)Apply a reaction force loading device to load the pressure-bearing steel cylinder to the design load; the design load is one of the divided design implementation target pressures of the construction target in step (1). (4)Pour structural adhesive between the composite high-strength fabric material and the implementation target, and wait for the structural adhesive to cure. (5)Release the load on the pressure-bearing steel cylinder and remove the pressure-bearing steel cylinder. (6)Repeat steps (2) to (5) until each portion in step (1) is constructed.

[0007] The further improvement of the above solution is that in step (2), the construction target position is pre-treated, the surface floating slurry and dust are cleaned, grouting grooves are set, grouting nozzles, air outlets and overflow ports are installed.

[0008] The further improvement of the above solution is that gaskets are sewn on the composite high-strength fabric material in step (2).

[0009] The further improvement of the above solution is that heating sheets are installed on the outer surface of the pressure-bearing steel cylinder and covered with a degumming material.

[0010] The further improvement of the above solution is that in step (4), a clay material is used to seal both ends of the gap between the pressure-bearing steel cylinder and the construction target.

[0011] The further improvement of the above solution is that if the construction target needs to be constructed in sections, first complete one of the divided design implementation target pressures for each section, and repeat this until each section and each portion are constructed.

[0012] The method for implementing circumferential prestress in the pipe in stages and layers provided by the present invention can greatly reduce the stiffness and strength requirements of the reaction device, and can greatly reduce the capacity requirements of the loading device; at the same time, it reduces the strength requirements during form removal, reduces the curing waiting time of the single-layer adhesive, and reduces the impact of the single-time system conversion on the system. The present invention is a major improvement and development based on the theory and method of circumferential prestress in the pipe. It proposes a method for reinforcement in stages and layers based on the method of circumferential prestress in the pipe, which is a breakthrough in the method. Based on the principle of circumferential prestress tending to be circular, a method for ensuring the thickness of the adhesive layer through a permeable cushion layer at a certain interval is proposed; for the requirements of the adhesiveness and non-stickiness of the structural adhesive during demoulding, a non-stick layer measure is proposed to solve the feasibility problem of construction in stages and layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be further described below with reference to the accompanying drawings.

[0014] Figure 1 It is a schematic diagram of the construction structure of the first layer in a preferred embodiment of the present invention.

[0015] Figure 2It is a schematic diagram of the construction structure of the second layer in a preferred embodiment of the present invention.

[0016] Figure 3 It is a schematic diagram of the pressure-bearing steel cylinder structure in a preferred embodiment of the present invention.

[0017] Figure 4 It is a schematic diagram of the perfusion structure in a preferred embodiment of the present invention. Detailed implementation manners Embodiment

[0018] The method for implementing circumferential prestress in the pipe in stages and layers in this embodiment includes the following steps: (1) According to the requirements of the construction target, divide the designed implementation target pressure of the construction target into several parts; for example, when the water pressure is to be increased by 0.3 MPa for the target, it can be divided into 0.1 MPa in the first stage, 0.1 MPa in the second stage, and 0.1 MPa in the third stage; the loading value for each stage is only 0.1 MPa, which can greatly reduce the stiffness and strength requirements of the reaction equipment and can greatly reduce the weight of the loading device; at the same time, it reduces the strength requirements during form removal, reduces the curing waiting time of the single-layer glue, and reduces the impact on the system caused by a single system conversion.

[0019] (2) Pretreat the construction target position, including: cleaning the surface floating slurry and dust, setting up grouting grooves, installing grouting nozzles, air outlets and overflow ports, as Figure 4 shown, arrange the pressure-bearing steel cylinder at the construction target position, and evenly sleeve the composite high-strength fabric material on the outer surface of the pressure-bearing steel cylinder; a non-stick material coating is compounded on the outer surface of the pressure-bearing steel cylinder, so as to facilitate the debonding after construction. Heating sheets are also arranged on the outer surface of the pressure-bearing steel cylinder. The pressure-bearing steel cylinder is formed by curling a plate, and the two ends of the plate are overlapped in a lapped manner, so that the pressure-bearing steel cylinder can expand under the action of internal pressure. The structure of the pressure-bearing steel cylinder is as Figure 3 shown.

[0020] Gaskets are sewn on the composite high-strength fabric material. The gaskets have permeability, certain stiffness, strength and good bonding performance. Considering that it is difficult to measure and maintain the coaxiality between the PCCP and the pressure-bearing steel cylinder during the construction process, therefore, gaskets that can ensure a minimum gap is reserved between the pressure-bearing steel cylinder and the inner wall of the construction target are added as the space for accommodating the structural adhesive. Generally, the thickness of the composite high-strength fabric material is between 0.1 mm and 0.2 mm, and the thickness of the gasket is between 2 mm and 3 mm. Based on the circumferential prestress circularization principle, there is a reasonable grouting space between the composite fabric and the bonding interface after the prestress is applied, which ensures the final thickness of the glue layer and improves the interlayer mechanical properties.

[0021] (3) Install the reaction force loading equipment. In this implementation, an airbag-type loading equipment is adopted, including an airbag, a loading air pump, and a pressure monitoring device; by pumping gas, pressure is applied from the inside of the pressure-bearing steel cylinder to cause expansion. By applying the reaction force loading equipment, the pressure-bearing steel cylinder is loaded to the design load; the design load is one of the divided design implementation target pressures of the construction target in step (1); (4) Use the clay material to seal both ends of the gap between the pressure-bearing steel cylinder and the construction target. Pour the structural adhesive through the overflow port between the composite high-strength fabric and the implementation target to fully impregnate and fuse the structural adhesive with the composite high-strength fabric; after the glue pouring is completed, turn on the heating sheet to increase the temperature and the curing rate; The structure of the first-phase project is as Figure 1 shown.

[0022] (5) After the structural adhesive cures to reach the allowable value, start the system conversion, gradually reduce the applied pressure of the reaction force loading equipment, and the structural adhesive gradually bears and releases the load of the pressure-bearing steel cylinder, and finally remove the pressure-bearing steel cylinder.

[0023] (6) If the number of portions divided in step (1) is greater than 1, repeat steps (2) to (5) until each portion in step (1) is constructed. Among them, the structure of the second-phase project is as Figure 2 shown.

[0024] If the construction target needs to be constructed in segments, first complete one of the divided design implementation target pressures for each segment, and repeat this until each segment and each portion are constructed. In this way, prestress can be uniformly applied to all construction targets. Compared with the existing prestress scheme of constructing all design targets at once, if there are adjustments in the subsequent construction segments, multi-stage construction can still be used to achieve them. For segmented construction, the first layer of the first stage can be grouted with inclined holes, and for the second and third layers and later, small holes with a diameter of 5-8 mm can be opened at the support pressure-bearing cylinder to solve the problems of glue pouring and air outlet.

[0025] The present invention is not limited to the specific technical solutions described in the above embodiments. In addition to the above embodiments, the present invention can also have other implementation manners. Any technical solutions formed by equivalent substitution are within the protection scope required by the present invention.

Claims

1. A method for implementing circumferential prestress in a pipe in stages and layers, characterized in that, It includes the following steps: (1) Divide the designed implementation target pressure of the construction target into several parts according to the requirements of the construction target; (2) Arrange the pressure-bearing steel cylinder at the construction target position, and evenly sleeve the composite high-strength fabric outside the surface of the pressure-bearing steel cylinder; (3) Apply the reaction force loading equipment to load the pressure-bearing steel cylinder to the designed load; the designed load is one of the parts divided from the designed implementation target pressure of the construction target in step (1); (4) Pour structural adhesive between the composite high-strength fabric and the implementation target, and wait for the structural adhesive to cure; (5) Release the load of the pressure-bearing steel cylinder and remove the pressure-bearing steel cylinder; (6) Repeat steps (2) to (5) until each part in step (1) is constructed; 2. The method for implementing circumferential prestress in a pipe in stages and layers according to claim 1, wherein: In step (2), pre-treat the construction target position, clean the surface floating slurry and dust, set up grouting grooves, install grouting nozzles, air outlets and overflow outlets.

3. The method for implementing circumferential prestress in a pipe in stages and layers according to claim 1, characterized in that: In step (2), gaskets are sewn on the composite high-strength fabric.

4. The method for implementing circumferential prestress in a pipe in stages and layers according to claim 1, characterized in that: Heating sheets are installed on the outer surface of the pressure-bearing steel cylinder and covered with degumming materials.

5. The method for implementing circumferential prestress in the pipe in stages and layers according to claim 1, characterized in that: In step (4), use the mastic material to seal both ends of the gap between the pressure-bearing steel cylinder and the construction target.

6. The method for implementing circumferential prestress in a pipe in stages and layers according to claim 1, characterized in that: If the construction target needs to be constructed in sections, first complete one of the parts divided from the designed implementation target pressure of each section, and repeat this until each section and each part are constructed.

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