UHPC assembled open channel lining structure and design method thereof

Abstract

The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open channel lining structure and a design method thereof, and relates to the technical field of hydraulic engineering. The application discloses a UHPC assembled open

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering technology, specifically to a UHPC prefabricated open channel lining structure and its design method. Background Technology

[0002] In recent years, my country's irrigation projects have entered a stage of high-quality development. Open channels, as key structures in irrigation projects, undertake crucial tasks such as efficient water transport, ensuring stable and safe water supply along the route, and regulating regional water resource allocation. However, traditional rectangular open channels using ordinary plain concrete or cast-in-place reinforced concrete require multiple steps, including formwork support, rebar tying, concrete pouring, and curing. This complex and time-consuming process demands significant manpower and resources. Furthermore, open-air operations are susceptible to constraints from climate, environment, and geological conditions, making quality control difficult and potentially causing negative impacts on the surrounding ecological environment due to vegetation damage or improper material storage. While using precast concrete assembly structures can shorten the on-site construction period to some extent, the performance limitations of conventional concrete necessitate increased segment wall thickness to meet load-bearing requirements, resulting in a high self-weight per segment. To facilitate transportation and hoisting, segment lengths often need to be shortened, inevitably increasing the number of on-site assembly joints and significantly increasing the risk of channel leakage. In addition, the concrete material of traditional rectangular open channels does not have the ability to self-heal cracks. During operation, it is prone to micro-cracks and gradual expansion due to multiple factors such as temperature stress, drying shrinkage deformation, uneven foundation settlement and water erosion. Once cracked, it cannot recover on its own, which not only reduces the load-bearing capacity, durability and service life of the structure, but also requires high-frequency maintenance, which increases costs and affects the continuity of normal water conveyance.

[0003] With the continuous development and progress of materials science and structural engineering, new building materials characterized by lightweight, high strength, and excellent durability are constantly emerging. Innovative structural forms such as spatial grid structures, monolithic structures, and prefabricated systems are making continuous breakthroughs. New materials and structures, as emerging technologies, have been widely applied in various engineering fields such as civil engineering, water conservancy, and architecture. Therefore, how to integrate new materials and structures on the basis of existing rectangular open channel technology to promote the development of rectangular open channels towards lightweight, high efficiency, greater durability, and greater economy, and significantly improve the entire life cycle of modern irrigation engineering open channels, has become an urgent problem to be solved in the field of water conservancy engineering channel technology. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a UHPC prefabricated open channel lining structure and its design method. This solution utilizes the ultra-high performance of UHPC, combined with a novel structure, to gradually optimize existing rectangular open channel structures, achieving lightweight, high-strength, and durable design while improving material utilization and shortening construction time.

[0005] This invention is achieved through the following technical solution:

[0006] A UHPC prefabricated open channel lining structure includes:

[0007] The segmented channel body has a bottom with a uniform thickness design, and the sidewalls of the segmented channel body have progressively increasing thickness from top to bottom;

[0008] The top and bottom of the sidewalls of the segmental channel body are respectively provided with top beams and bottom beams with dimensions larger than the sidewalls;

[0009] Several transverse ribs are provided on the outer side wall of the segmental channel body. The transverse ribs are evenly distributed along the length direction of the segmental channel body, and the upper and lower ends of the transverse ribs are connected to the top beam and the bottom beam, respectively.

[0010] In a further optimization, the upper end of the sidewall of the segmental channel body is inclined outward by 2 to 5 degrees relative to the vertical plane.

[0011] For further optimization, the segmental channel body is made of UHPC material and incorporating fine steel fibers and cement-based crystalline materials.

[0012] In a further optimization, the two end faces of the segmental channel body are respectively provided with a splicing water-stop groove and a splicing water-stop protrusion arranged circumferentially, and the splicing water-stop groove and the splicing water-stop protrusion are mutually compatible; the splicing water-stop protrusion at one end of the segmental channel body can be inserted into the splicing water-stop groove at the end of another segmental channel body; a foam board is also filled between the splicing water-stop protrusion and the splicing water-stop groove, and the foam board is filled with asphalt concrete.

[0013] Further solutions:

[0014] This invention also provides a design method for UHPC prefabricated open channel lining structure, comprising the following steps:

[0015] The cross-sectional parameters of the channel are determined based on hydraulic calculations, including the net width b and net height h; and the segment length L of the channel is determined based on the actual transportation and hoisting conditions of the project.

[0016] The maximum earth pressure P acting on the channel sidewall is determined based on the physical and mechanical properties of the soil and the actual boundary conditions. a And the bending moment M caused by earth pressure on the outer wall of the channel 土 ;

[0017] The most unfavorable internal water pressure P acting on the inner wall of the channel is determined based on the full water level. w And the bending moment M caused by water pressure on the inner wall 水 ;

[0018] Based on the stress distribution cloud map of the channel section established by the above stress, the channel structure is designed according to the stress distribution cloud map, and the structural dimensions of each part of the channel are initially determined to obtain the segmental channel body;

[0019] Subsequently, structural safety calculations and reinforcement design were performed on the obtained segmental channel body;

[0020] For the channel segments that meet safety requirements, a three-dimensional finite element model is constructed for analysis to obtain stress and deformation distribution. It is then determined whether the stress of the structure exceeds the material's strength design value and whether the structural deformation affects its use. If the stress exceeds the material's strength design value or the structural deformation affects its use, the structural dimensions of each part of the channel segment itself are re-determined.

[0021] Further optimization involves simulating the prefabrication and demolding process of a rectangular open channel to optimize the sidewall slope of the segmental channel body, if the stress of the structure does not exceed the design strength value of the material and the structural deformation does not affect the use. This is done to determine the optimal slope parameters and obtain the final segmental channel body structure.

[0022] Further optimization yields the following formulas for structural safety verification and reinforcement design of the obtained segmental channel body:

[0023] and ;

[0024] In the formula, f y This represents the design value for the tensile strength of ordinary longitudinal reinforcing bars. , σ represents the cross-sectional area of ​​ordinary reinforcing bars in the tension and compression zones; t This represents the design value for the tensile strength of UHPC material. For the sidewall thickness, For the thickness of the base plate, The number of transverse ribs is 4. The width of the transverse rib. The thickness is the transverse rib.

[0025] Further optimization, after obtaining and manufacturing the segmental channel body that meets the requirements, also includes a step of structural verification of the segmental channel body, specifically including:

[0026] Experiments were conducted on the inner and outer sides of the segmental channel body to apply progressively increasing loads to test the ultimate bearing capacity of the segmental channel body. The results were then compared with theoretical calculations and finite element analysis to evaluate the safety margin of the design.

[0027] During the loading process, the deformation of key parts of the structure is accurately measured to obtain the load-displacement curve, and the stiffness, ductility and deformation recovery capacity of the structure are analyzed.

[0028] Meanwhile, during the loading process, the entire process of cracks from their appearance and expansion to their final failure was observed and recorded. The morphology, distribution, and width development of the cracks were analyzed to verify the crack control capability of UHPC.

[0029] Finally, the failure modes and mechanisms of the structure under extreme conditions are clarified, thus providing a basis for optimizing structural design and construction measures.

[0030] Further optimization involves experimental steps of applying progressively increasing loads to the outer side of the segmental channel body, including:

[0031] Lay the segmental channel body flat on the ground on one side;

[0032] A heightening block is installed below the opening of the segmental channel body, and a displacement meter is installed between the top of the heightening block and the upper side of the opening.

[0033] Fill the recessed areas on the top sidewall of the segmental channel body with dry sand and level them;

[0034] Subsequently, loads were placed on top of the segmental channel body, and the weight of the loads placed on top was gradually increased at regular intervals to test the ultimate bearing capacity of the segmental channel body and obtain the load-displacement curve of the deformation.

[0035] Further optimization involves experimental steps of applying progressively increasing loads to the inner side of the segmental channel body, including:

[0036] Lay the bottom of the segmental channel body flat on the ground;

[0037] A heightening block is installed on the bottom surface inside the segmental channel body, and a displacement meter is installed between one side of the heightening block and the inner wall of the segmental channel body.

[0038] Jacks and auxiliary facilities are installed sequentially between the two sides inside the opening of the segment channel body, so that the two ends of the jacks abut against the inside of the segment channel body and the auxiliary facilities respectively.

[0039] Subsequently, the load applied by the jacks was gradually increased at regular intervals to test the ultimate bearing capacity of the channel segment and obtain the load-displacement curve of the deformation.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] 1. This invention provides a UHPC prefabricated open channel lining structure and its design method. Utilizing the high strength of UHPC, the lining wall thickness is reduced, segment weight is lightened, and transportation is facilitated while increasing segment length, thus reducing the number of joints and lowering the risk of leakage. Secondly, the bottom plate adopts a uniform thickness design, and the sidewalls gradually thicken from top to bottom, closely matching the distribution law of water and soil pressure and fully utilizing the material's properties. Furthermore, top and bottom beams are locally enlarged at the top and bottom of the channel body, and transverse ribs are longitudinally spaced on the outer side of the channel body, forming an overall frame structure. This improves the overall rigidity and load-bearing capacity of the channel body, while concentrating stress mainly in the area where the transverse ribs and bottom beams intersect. This achieves a further reduction in sidewall thickness, except for the transverse ribs, top beams, and bottom beams, thereby reducing the weight of the channel body and improving material utilization without affecting its normal function.

[0042] 2. The present invention provides a UHPC prefabricated open channel lining structure and its design method. Through the design method of frame open channel structure, and verified by prototype test, the safety of the structure can be well guaranteed.

[0043] 3. This invention provides a UHPC prefabricated open channel lining structure and its design method. It proposes adding cement-based crystalline materials to the UHPC, enabling the open channel segments to self-repair under the action of water flow when micro-cracks appear during operation. This improves durability and service life, reduces maintenance frequency and costs, and ensures the continuity of water conveyance. Furthermore, this invention further optimizes the slope design of the inner side of the channel (optimal slope is 2~5°), successfully solving the demolding problem in the prefabrication of rectangular open channels and effectively avoiding prefabrication damage.

[0044] 4. This invention provides a UHPC prefabricated open channel lining structure and its design method, enabling rectangular open channels to be prefabricated in the factory and transported to the site for assembly. Regardless of whether the terrain is soft soil, hard soil, or remote mountainous areas, installation can begin immediately after channel excavation. This improves construction safety, work efficiency, and shortens the construction cycle while effectively protecting the ecological environment, aligning with the concept of green development. The integrated approach of "high-performance materials" and "optimized structure" lays the foundation for the future development of lining technology in water conservancy projects. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0046] Figure 1 Three-dimensional finite element model and simulation calculation stress cloud map of traditional rectangular open channel;

[0047] Figure 2 Comparison of 3D models of traditional rectangular open channels and UHPC rectangular open channels;

[0048] Figure 3 Stress cloud diagram for three-dimensional finite element simulation of a UHPC rectangular open channel;

[0049] Figure 4 Stress distribution cloud map and sidewall gradual thickness design drawing for UHPC rectangular open channel section;

[0050] Figure 5 A three-dimensional diagram of the overall framework structure of the segmental channel body;

[0051] Figure 6 Stress cloud diagram for three-dimensional finite element simulation of the segmental channel body;

[0052] Figure 7 This is a schematic diagram of the inner slope of the cross-section of the segmental channel body;

[0053] Figure 8 Flowchart of the design methodology for UHPC prefabricated open channel lining structures;

[0054] Figure 9 A schematic diagram showing the dimensions of the segmental channel body;

[0055] Figure 10 3D perspective view of channel reinforcement for verification process;

[0056] Figure 11 This is a diagram showing the loading arrangement for the external pressure load test.

[0057] Figure 12 This is a diagram showing the loading arrangement for the internal pressure load test.

[0058] Figure 13 Diagram showing the layout of the external pressure monitoring system;

[0059] Figure 14 Diagram showing the layout of the internal pressure monitoring system;

[0060] Figure 15 The load-deformation diagram for the external pressure load test is shown.

[0061] Figure 16 This is a schematic diagram of the deformation along the length of the trench during the external pressure load test.

[0062] Figure 17 The load-deformation diagram for the internal pressure load test;

[0063] Figure 18This is a schematic diagram of the load-strain curve for an external pressure test.

[0064] Figure 19 This is a diagram showing the strain distribution on the side section during the external pressure test.

[0065] Figure 20 This is a schematic diagram of the load-strain curve for an internal pressure test.

[0066] Figure 21 This is a diagram showing the strain distribution on the side section during the internal pressure experiment.

[0067] The attached diagram shows the markings and corresponding component names:

[0068] 1-Segmental channel body, 2-Top beam, 3-Bottom beam, 4-Transverse rib. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0070] Example 1: This Example 1 provides a UHPC prefabricated open channel lining structure, such as... Figure 5 and Figure 9 As shown, it includes:

[0071] The segmental channel body 1 has a bottom with a uniform thickness design, and the sidewalls of the segmental channel body 1 have progressively increasing thickness from top to bottom.

[0072] The top and bottom of the sidewall of the segmental channel body 1 are respectively provided with a top beam 2 and a bottom beam 3 with a size larger than the sidewall;

[0073] Several transverse ribs 4 are provided on the outer side wall of the segment channel body 1. The transverse ribs 4 are evenly distributed along the length direction of the segment channel body 1, and the upper and lower ends of the transverse ribs 4 are connected to the top beam 2 and the bottom beam 3, respectively.

[0074] In this embodiment, the upper end of the side wall of the segment channel body 1 is inclined outward by 2 to 5 degrees relative to the vertical plane.

[0075] In this embodiment, the segmental channel body 1 is made of UHPC material and incorporating fine steel fibers and cement-based crystalline materials.

[0076] In this embodiment, the two end faces of the segment channel body 1 are respectively provided with a splicing water-stop groove and a splicing water-stop protrusion arranged circumferentially, and the splicing water-stop groove and the splicing water-stop protrusion are mutually compatible; the splicing water-stop protrusion at one end of the segment channel body 1 can be inserted into the splicing water-stop groove at the end of another segment channel body 1; a foam board is also filled between the splicing water-stop protrusion and the splicing water-stop groove, and the foam board is filled with asphalt concrete.

[0077] In summary, based on the excellent mechanical properties of UHPC, this invention proposes a frame-type open channel lining structure, consisting of a channel body, a load-bearing frame, and a water-stopping structure. The channel body is the main seepage-proof structure, with a uniform thickness bottom slab and gradually thickening sidewalls from top to bottom. Locally enlarged sections at the bottom and top of the channel form a top beam 2 and a bottom beam 3, which, together with the transverse ribs 4 on the outer side of the channel body, form the load-bearing frame structure. Expansion joints are sealed with foam board-filled asphalt concrete to form a seepage-proof system. Furthermore, the lining material is UHPC with self-healing properties, enabling self-repair during normal use.

[0078] The invention utilizes ultra-high performance concrete (UHPC) with self-healing properties, incorporating fine steel fibers (2% for structural use) and cement-based crystalline materials. This enables UHPC to exhibit axial tensile strain hardening properties, resulting in considerable post-cracking tensile strength, good toughness, and the ability to limit crack propagation. Simultaneously, when microcracks appear in open channel sections during operation, they can self-repair under the action of water flow, thereby improving their durability and service life, reducing maintenance frequency and costs, and ensuring continuous water supply. Without reducing the load-bearing capacity of the segments, the structure is optimized step by step. First, the high strength of UHPC is utilized to reduce the wall thickness of the segments, thereby reducing weight and facilitating transportation while increasing the segment length, which to some extent reduces the number of joints and lowers the risk of leakage. Second, based on the distribution law of water and soil pressure, the bottom plate adopts a uniform thickness design, while the side walls gradually thicken from top to bottom to fully utilize the material properties. In addition, based on the stress distribution characteristics of the segments, the top and bottom beams 2 and 3 are locally enlarged, and transverse ribs 4 are set longitudinally at intervals on the outside of the channel body to form an overall frame structure, thereby improving the overall rigidity and load-bearing capacity of the channel body. At the same time, the stress is mainly concentrated in the area where the transverse ribs 4 and the bottom beams 3 intersect, further achieving the reduction of wall thickness, weight reduction of the channel body, and improvement of material utilization. Furthermore, to solve the demolding problem in the prefabrication production of rectangular open channels, this invention optimizes the design of its inner slope, effectively avoiding prefabrication damage. This invention allows for prefabrication in the factory and assembly on-site. Regardless of whether the terrain is complex, such as soft soil, hard soil, or remote mountainous areas, installation can begin immediately after channel excavation. This improves construction safety, efficiency, and shortens the construction cycle while effectively protecting the ecological environment, aligning with the concept of green development. Through a two-pronged approach of "high-performance materials" and "optimized structure," the prefabricated UHPC rectangular open channel system possesses characteristics such as lightweight, high strength, durability, self-healing cracks, and ease of assembly. Especially for water conveyance channels in remote areas, it can significantly improve construction quality, shorten construction time, and reduce maintenance costs, laying the foundation for the future development of water conservancy engineering lining technology.

[0079] Example 2: This Example 2 is a further optimization based on Example 1, such as... Figures 1-9 As shown, a design method for UHPC prefabricated open channel lining structure is provided, including the following steps:

[0080] The cross-sectional parameters of the channel are determined based on hydraulic calculations, including the net width b and net height h; and the segment length L of the channel is determined based on the actual transportation and hoisting conditions of the project.

[0081] The maximum earth pressure P acting on the channel sidewall is determined based on the physical and mechanical properties of the soil and the actual boundary conditions. a And the bending moment M caused by earth pressure on the outer wall of the channel 土 ;

[0082] The most unfavorable internal water pressure P acting on the inner wall of the channel is determined based on the full water level. w And the bending moment M caused by water pressure on the inner wall 水 ;

[0083] Based on the stress distribution cloud diagram of the channel section established by the above-mentioned stress distribution cloud diagram, the channel structure is designed according to the stress distribution cloud diagram, and the structural dimensions of each part of the channel itself are initially determined to obtain the segmental channel body 1; the structural dimensions include: wall thickness t1, bottom plate thickness t2, number of ribs n, and rib width b. j rib thickness t j (Based on structural testing recommendations, the following initial values ​​are selected: wall thickness t1 = 5cm, base plate thickness t2 = 8cm, number of ribs n = 3, rib width b) j =10cm, rib thickness t j =5cm);

[0084] If the stress of the structure does not exceed the design strength value of the material and the structural deformation does not affect the use, the prefabrication and demolding process of the rectangular open channel is further simulated to optimize the side wall slope of the segment channel body 1 in order to determine the optimal slope parameters and obtain the final segment channel body 1 structure.

[0085] Subsequently, structural safety calculations and reinforcement design were performed on the obtained segmental channel body 1; the formulas for structural safety calculations and reinforcement design of the obtained segmental channel body 1 are as follows:

[0086] and ;

[0087] In the formula, f y This represents the design value for the tensile strength of ordinary longitudinal reinforcing bars. , σ represents the cross-sectional area of ​​ordinary reinforcing bars in the tension and compression zones; t This represents the design value for the tensile strength of UHPC material. For the sidewall thickness, For the thickness of the base plate, The number of transverse ribs is 4. The width of the transverse rib. The thickness is the transverse rib.

[0088] For the channel body 1 that meets the safety requirements, a three-dimensional finite element model is constructed for analysis to obtain the stress and deformation distribution, and to determine whether the stress of the structure exceeds the material strength design value and whether the structural deformation affects the use. If it exceeds the material strength design value or the structural deformation affects the use, the structural dimensions of each part of the channel body 1 are re-determined.

[0089] If the stress of the structure does not exceed the design strength value of the material and the structural deformation does not affect the use, the prefabrication demolding process of the rectangular open channel is further simulated to optimize the side wall slope of the segment channel body 1 in order to determine the optimal slope parameters, thereby solving the demolding problem, reducing prefabrication damage, and obtaining the final segment channel body 1 structure.

[0090] In summary, this invention achieves weight reduction in lining through structural optimization and material improvement, solving problems such as the heavy weight, easy cracking, low construction efficiency, and short service life of traditional concrete linings. It features lightweight, high durability, and rapid assembly, and can significantly improve construction quality, save construction time, and reduce maintenance costs, especially for water conveyance channels in remote areas.

[0091] Example 3: This Example 3 is a further optimization based on Example 2, such as... Figures 10-21 As shown, the steps for structural verification of the segmental channel body 1 are also provided. Verifying the structural bearing capacity and deformation performance (verifying the design bearing capacity and observing the deformation morphology), the structural model bearing capacity experiment is the key part of this study. Its main purpose is to directly verify the rationality and safety of the UHPC prefabricated rectangular open channel structure design through physical experiments.

[0092] 1. Verify bearing capacity: Test the ultimate bearing capacity of the model by applying progressively increasing loads, and compare the results with theoretical calculations and finite element analysis to evaluate the safety margin of the design.

[0093] 2. Observe deformation performance: During the loading process, accurately measure the deformation (deflection) of key parts of the structure, obtain the load-displacement curve, and analyze the structure's anti-toxicity, ductility, and deformation recovery ability.

[0094] 3. Study crack development: Observe and record the entire process of cracks from their appearance and expansion to their final failure, analyze the morphology, distribution and width development of cracks, and verify the crack control capability of UHPC.

[0095] 4. Determine the failure mode: Clarify the failure mode and failure mechanism of the structure under the ultimate state, so as to provide a basis for optimizing structural design and construction measures.

[0096] The specific steps described above are as follows:

[0097] 1. Test Model Fabrication: A prefabricated channel structure with a cross-sectional dimension of "800mm (width) × 1100mm (height) × 3000mm (length)" was initially selected for a full-scale model test. Each rib of the channel structure was reinforced with one D12 U-shaped steel bar and four D8 longitudinal distribution bars forming a steel reinforcement skeleton. Figure 10 As shown in the figure. Among them, D12 U-shaped reinforcement and D8 distribution reinforcement represent U-shaped reinforcing bars with a diameter of 12mm and distribution bars with a diameter of 8mm, respectively.

[0098] The prefabricated channels are produced using Q235 shaped steel molds and naturally cured for 28 days after production.

[0099] Loading scheme:

[0100] (1) External pressure load test scheme:

[0101] Place one side of the segmental channel body flat on the ground; install a heightening block below the opening of the segmental channel body, and install a displacement meter between the top of the heightening block and the upper side of the opening;

[0102] Fill the recessed areas on the top sidewall of the segmental channel body with dry sand and level them;

[0103] Subsequently, loads were placed on top of the segmental channel body, and the weight of the loads was gradually increased at regular intervals to test the ultimate bearing capacity of segmental channel body 1 and obtain the load-displacement curve of deformation. The loads were solid concrete blocks, 300mm×600mm×80mm in size, with a density of 23kN / m³, stacked continuously in staggered layers along the entire 3000mm length of the channel, for a total of 5 layers. A layer of approximately 30mm thick dry sand was laid at the bottom for leveling and to ensure uniform load distribution; each layer contained 10 blocks, for a total of 50 blocks across 5 layers.

[0104] The design parameter table is as follows:

[0105] Table 1: Test Parameters for External Pressure Load

[0106]

[0107] A four-stage incremental loading method was adopted, with a static resting time of no less than 1 hour after each loading stage, and deformation data at key time points were recorded:

[0108] Table 2: Deformation Data from External Pressure Load Test

[0109]

[0110] After each loading stage is completed, displacement and strain data are recorded at 0, 15, 30, and 60 minutes. The next loading stage can only be carried out after the structural deformation is confirmed to be stable.

[0111] The loading layout diagram of the above scheme is as follows: Figure 11 As shown.

[0112] (2) Test scheme for internal pressure load:

[0113] Lay the bottom of the segmental channel body flat on the ground;

[0114] A heightening block is installed on the bottom surface inside the segmental channel body, and a displacement meter is installed between one side of the heightening block and the inner wall of the segmental channel body.

[0115] Jacks and auxiliary facilities are sequentially installed between the inner sides of the opening of the segmental channel body, with the two ends of the jacks respectively abutting against the inner side of the segmental channel body and the auxiliary facilities; for example Figure 12 As shown;

[0116] Subsequently, the load applied by the jacks was gradually increased at regular intervals to test the ultimate bearing capacity of the channel segment 1 and obtain the load-displacement curve of the deformation.

[0117] The parameter table for each parameter is as follows:

[0118] Table 3: Test Parameters for Internal Pressure Load

[0119]

[0120] By employing a three-stage incremental loading method, the static resting time after each loading stage is no less than 1 hour, and deformation data at key time points are recorded:

[0121] Table 4: Deformation Data of Internal Pressure Load Test

[0122]

[0123] After each loading stage is completed, displacement and strain data are recorded at 0, 15, 30, and 60 minutes. The next loading stage can only be carried out after the structural deformation is confirmed to be stable.

[0124] 2. Detection system layout and data acquisition;

[0125] (1) External pressure monitoring layout scheme, such as Figure 13 As shown, three heightening blocks are installed side-by-side below the opening of the segmental channel body, each equipped with a displacement gauge and a strain gauge. See below:

[0126] The displacement gauges are dial gauges with a range of ±50 mm and a resolution of 0.01 mm, and three are arranged; the strain gauges are foil resistance strain gauges (model BX120-3AA), 12 plus 1 ambient temperature compensation gauge.

[0127] (2) The layout scheme for internal pressure monitoring, such as Figure 14 As shown, a heightening block is installed on the bottom surface inside the segmental channel body, and a displacement gauge and strain gauge are installed between one side of the heightening block and the inner wall of the segmental channel body. See below:

[0128] The displacement gauges are dial gauges with a range of ±50 mm and a resolution of 0.01 mm, and three are arranged; the strain gauges are foil resistance strain gauges (model BX120-3AA), 12 plus 1 ambient temperature compensation gauge.

[0129] (3) Vertical data acquisition process: Before loading, all strain gauges are zeroed; after each loading stage, data is recorded at 0, 15, 30 and 60 minutes; ambient temperature is recorded (for correction); output "load-strain curve", "section strain distribution diagram" and "longitudinal deformation distribution diagram".

[0130] 3. Termination conditions (safety control):

[0131] (1) Loading shall be stopped immediately if any of the following conditions occur:

[0132] (2) Visible cracks (width ≥ 0.2 mm) appear in the structure;

[0133] (3) Lateral displacement increment > 2 mm after single-stage loading or continues to develop;

[0134] (4) The maximum tensile strain exceeds 800 με (UHPC ultimate tensile strain reference value);

[0135] (5) The maximum compressive strain exceeds 2000 με;

[0136] (6) Obvious swelling, bending or localized crushing occurs;

[0137] (7) The total lateral displacement exceeds 5 mm;

[0138] (8) The longitudinal displacement difference exceeds 1 mm (indicating uneven stress); the required load is reached and no abnormal changes are observed for 30 minutes.

[0139] 4. Experimental process and subjects;

[0140] (1) External compression test process and phenomena:

[0141] Table 5: Procedure of External Compression Test

[0142]

[0143] (2) Internal pressure test process and phenomena:

[0144] Table 6: Internal Compression Test Procedure

[0145]

[0146] 5. Experimental Results and Analysis;

[0147] (1) Differences in mechanical response at the location of lateral pressure (e.g.) Figure 15 (as shown)

[0148] The pressure-deformation curves on the outer side reflect the difference in bearing capacity between the channel ends and the mid-span: under the same deformation, the load at the ends (left and right ends) is significantly higher than that at the mid-span: for example, when the deformation reaches 3 mm, the load at the right end is about 9 kPa, while that at the mid-span is only about 4 kPa.

[0149] During the deformation growth process, the load growth rate at the end is always faster than that at the mid-span, indicating that the initial stiffness and bearing efficiency at the end of the channel are better (related to the end constraint conditions and cross-sectional stress distribution), while the mid-span is a relatively weak area dominated by bending.

[0150] (2) Spatial distribution pattern of deformation (e.g.) Figure 16 (as shown)

[0151] Under different external loads, the deformation along the groove length (0~3000mm) exhibits the characteristics of a bending member that is "large in the middle and small at both ends":

[0152] The midpoint of the groove (at 1500mm) is the deformation concentration zone: the greater the load, the more significant the deformation at the midpoint (e.g., under a 9.20kPa load, the deformation at the midpoint is nearly 6mm).

[0153] The deformation at both ends of the tank is close to zero, and Figure 1 The conclusion that "the end load is high and the stiffness is large" is consistent with the conclusion that "the end constraint is strong and the mid-span flexibility is large" in the spatial force logic.

[0154] (3) Mechanical response of inner constraints (e.g.) Figure 17 (as shown)

[0155] The internal pressure-deformation curve reflects the constrained bearing capacity of the structure: the internal pressure continues to rise with deformation, with no decreasing segment (the load reaches 14kN when the deformation is 1mm), showing a "reinforced" response.

[0156] This indicates that the inner side of the channel can provide a stable constraint reaction force, forming a force balance with the outer side pressure, thus ensuring the overall stability of the structure under lateral pressure conditions.

[0157] (4) Performance compatibility of UHPC materials:

[0158] Figures 15-17 None of them exhibited the failure characteristics of "sudden drop in stiffness and loss of load-bearing capacity," demonstrating the core advantages of UHPC materials:

[0159] High ductility: During large deformations (Figure 16, midpoint deformation is nearly 6mm), Figure 17 Even with a deformation of 1 mm, the load continued to increase without brittle failure.

[0160] High load-bearing redundancy: Both the inner and outer sides exhibit a trend of "deformation-load synchronous strengthening", which is suitable for engineering conditions where the channel is subjected to lateral soil pressure for a long time.

[0161] In summary, the lateral pressure stress of the precast rectangular UHPC channel exhibits a spatial characteristic of "rigid at the ends and flexible in the middle of the span". Deformation is concentrated in the middle of the span, the load-bearing core is at the ends, and the inner and outer forces have good coordination.

[0162] UHPC material endows the structure with good ductility and load-bearing redundancy, and its lateral pressure performance is stable and reliable.

[0163] 6. Stress distribution pattern:

[0164] like Figures 18-21 As shown, the analysis is conducted from four aspects: external pressure strain characteristics, internal pressure strain characteristics, stress synergy law, and material properties.

[0165] (1) Strain characteristics of external pressure test:

[0166] Under external pressure conditions, the channel cross-section exhibits bending deformation characteristics of "compression on the inner wall and tension on the outer wall": the load-strain difference is located in different parts (e.g., Figure 16 (as shown)

[0167] The outer wall of the middle root (brown line) shows obvious tensile strain (positive strain) as the load increases, which is the core area under tension under external pressure; the inner wall of the middle root (orange line) shows compressive strain (negative strain), which is the compression area; while the transition area (the inner and outer walls of the middle transition) has small strain fluctuations and more stable mechanical response.

[0168] Cross-sectional strain distribution (e.g.) Figure 19 As shown in the figure): within the same cross section, the strain signs of the inner wall (negative strain under all loads) and the outer wall (positive strain under all loads) are opposite, which is consistent with the strain distribution law of bending members; the larger the load (such as 9.25 kPa), the more significant the strain gradient of the cross section under compression-tension, and the stronger the bending deformation characteristics.

[0169] (2) Strain characteristics of the internal pressure test:

[0170] Calculations based on strain data and UHPC elastic modulus (taken as 35~40 GPa) show that:

[0171] External pressure condition: The root core area was analyzed, and the results are shown in the table below:

[0172] Table 7: Results of External Pressure Condition Analysis

[0173]

[0174] Internal pressure condition: Analysis was conducted on the root core area, and the results are shown in the table below:

[0175] Table 8: Results of Internal Pressure Condition Analysis

[0176]

[0177] The strength design values ​​for UHPC are typically: tensile design strength ≥ 6 MPa, and compressive design strength ≥ 100 MPa. In the tests, the actual tensile stress of UHPC under external pressure was 6.12~16.47 MPa, and the actual compressive stress was 1.59~9.46 MPa; under internal pressure, the actual tensile stress was 4.43~6.27 MPa, and the actual compressive stress was 2.84~5.36 MPa. No cracking or failure was observed under either internal or external pressure loads. Therefore, it can be concluded that the strength of the UHPC precast channel fully meets the design requirements. Furthermore, the test results indicate that the channel has at least a safety factor of 2, the specific safety factor to be determined by further destructive testing.

[0178] (3) Verification of UHPC material performance compatibility:

[0179] Throughout the test, the load-displacement curve showed no decreasing segment, and the strain increased linearly or gradually with the load. No brittle failure or sudden drop in stiffness due to stress concentration was observed, demonstrating the advantages of UHPC in terms of "high ductility and low brittleness".

[0180] Even under maximum deformation (nearly 6 mm at mid-span), the material can still withstand stress stably without crack propagation or loss of load-bearing capacity;

[0181] The difference between the actual stress and the design stress further proves that the high strength characteristics of UHPC provide reliable safety redundancy for the channel, and are suitable for the complex working conditions such as long-term bearing of lateral soil pressure and internal water pressure in engineering.

[0182] (4) Conclusion:

[0183] The precast rectangular UHPC channel exhibits clear stress characteristics under lateral pressure (superior end bearing capacity, concentrated deformation at mid-span, and reverse bending of the cross-section under internal and external pressure). Furthermore, the actual stress of the UHPC material is lower than its design strength stress, demonstrating a certain degree of structural safety and reserve capacity. The synergy between the high mechanical properties of UHPC and its structural design ensures the channel's stability and reliability under lateral pressure conditions, providing experimental evidence for its engineering applications.

[0184] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A design method for UHPC prefabricated open channel lining structure, characterized in that, UHPC prefabricated open channel lining structure includes: segmental channel body (1), the bottom of the segmental channel body (1) is designed with equal thickness, and the sidewall of the segmental channel body (1) increases in thickness from top to bottom; The top and bottom of the sidewall of the segmental channel body (1) are respectively provided with a top beam (2) and a bottom beam (3) with a size larger than the sidewall. Several transverse ribs (4) are provided on the outer side wall of the segment channel body (1). The transverse ribs (4) are evenly distributed along the length direction of the segment channel body (1), and the upper and lower ends of the transverse ribs (4) are connected to the top beam (2) and the bottom beam (3) respectively. The design method includes the following steps: The cross-sectional parameters of the channel are determined based on hydraulic calculations, including the net width b and net height h; and the segment length L of the channel is determined based on the actual transportation and hoisting conditions of the project. The maximum earth pressure P acting on the channel sidewall is determined based on the physical and mechanical properties of the soil and the actual boundary conditions. a And the bending moment M caused by earth pressure on the outer wall of the channel 土 ; The most unfavorable internal water pressure P acting on the inner wall of the channel is determined based on the full water level. w And the bending moment M caused by water pressure on the inner wall 水 ; Based on the stress distribution cloud map of the channel section established by the above stress, the channel structure is designed according to the stress distribution cloud map, and the structural dimensions of each part of the channel are initially determined to obtain the segmental channel body (1). Subsequently, structural safety calculations and reinforcement design were performed on the obtained segmental channel body (1); For the safety-compliant segment channel body (1), a three-dimensional finite element model is constructed for analysis to obtain stress and deformation distribution, and to determine whether the stress of the structure exceeds the strength design value of the material and whether the structural deformation affects the use. If it exceeds the strength design value of the material or the structural deformation affects the use, the structural dimensions of each part of the segment channel body (1) are re-determined. After obtaining and manufacturing the segment channel body (1) that meets the requirements, the process also includes a step of structural verification of the segment channel body (1), specifically including: Experiments were conducted on the inner and outer sides of the segment channel body (1) with progressively increasing loads to test the ultimate bearing capacity of the segment channel body (1) and compare it with theoretical calculations and finite element analysis results to evaluate the safety reserve of the design. During the loading process, the deformation of key parts of the structure is accurately measured to obtain the load-displacement curve, and the stiffness, ductility and deformation recovery capacity of the structure are analyzed. Meanwhile, during the loading process, the entire process of cracks from their appearance and expansion to their final failure was observed and recorded. The morphology, distribution, and width development of the cracks were analyzed to verify the crack control capability of UHPC. Finally, the failure modes and mechanisms of the structure under extreme conditions are clarified, thus providing a basis for optimizing structural design and construction measures; The experimental steps for applying progressively increasing loads to the outer side of the segmental channel body (1) include: Place one side of the segmental channel body (1) flat on the ground; A heightening block is installed on the lower side of the opening position of the segment channel body (1), and a displacement meter is installed between the top of the heightening block and the upper side of the opening position. Fill the recessed area on the top sidewall of the segmental channel body (1) with dry sand and level it; Subsequently, loads were placed on top of the segment channel body (1), and the weight of the loads placed on top was gradually increased at regular intervals to test the ultimate bearing capacity of the segment channel body (1) and obtain the load-displacement curve of the deformation. The experimental steps for applying progressively increasing loads to the inner side of the segmental channel body (1) include: Place the bottom of the segmental channel body (1) flat on the ground; A heightening block is installed on the bottom surface inside the segmental channel body (1), and a displacement meter is installed between one side of the heightening block and the inner wall of the segmental channel body (1). A jack and auxiliary facilities are installed between the two sides of the opening of the segment channel body (1) so that the two ends of the jack abut against the inside of the segment channel body (1) and the auxiliary facilities respectively. Subsequently, the load applied by the jack was gradually increased at regular intervals to test the ultimate bearing capacity of the segment channel body (1) and obtain the load-displacement curve of the deformation.

2. The design method for a UHPC prefabricated open channel lining structure according to claim 1, characterized in that, The upper end of the side wall of the segmental channel body (1) is inclined outward by 2 to 5 degrees relative to the vertical plane.

3. The design method for a UHPC prefabricated open channel lining structure according to claim 1, characterized in that, The segmental channel body (1) is made of UHPC material and mixed with fine steel fibers and cement-based crystalline materials.

4. The design method for a UHPC prefabricated open channel lining structure according to claim 1, characterized in that, The two end faces of the segment channel body (1) are respectively provided with splicing water-stop grooves and splicing water-stop protrusions arranged in the circumferential direction. The splicing water-stop grooves and splicing water-stop protrusions are mutually compatible. The splicing water-stop protrusion at one end of the segment channel body (1) can be inserted into the splicing water-stop groove at the end of another segment channel body (1). A foam board is also filled between the splicing water-stop protrusions and the splicing water-stop grooves. The foam board is filled with asphalt concrete.

5. The design method for a UHPC prefabricated open channel lining structure according to claim 1, characterized in that, If the stress of the structure does not exceed the strength design value of the material and the structural deformation does not affect the use, the prefabrication demolding process of the rectangular open channel is further simulated to optimize the side wall slope of the segment channel body (1) in order to determine the optimal slope parameters and obtain the final segment channel body (1) structure.

6. The design method for a UHPC prefabricated open channel lining structure according to claim 1, characterized in that, The formula for structural safety verification and reinforcement design of the obtained segmental channel body (1) is as follows: and ; In the formula, f y This represents the design value for the tensile strength of ordinary longitudinal reinforcing bars. , σ represents the cross-sectional area of ​​ordinary reinforcing bars in the tension and compression zones; t This represents the design value for the tensile strength of UHPC material. For the sidewall thickness, For the thickness of the base plate, The number of transverse ribs is 4. The width of the transverse rib. The thickness is the transverse rib.

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