Pavement precast slab structure with self-stress joint compensation for compensating slab end stress

Abstract

The application discloses a pre-tensioning method precast slab structure for a pavement, which compensates for the end stress of the slab by a self-stress joint, and belongs to the technical field of pavement construction. The pre-tensioning method precast slab structure comprises: pre-tensioning method precast slabs which are arranged at intervals and form a self-stress joint between the end portions of two adjacent pre-tensioning method precast slabs; the pre-tensioning method precast slab is composed of precast slab concrete, a plurality of longitudinal steel strands and a plurality of transverse steel bars which are uniformly arranged in the precast slab concrete; equidistant positioning spiral bars are cast in the precast slab concrete and fixed on the steel strands; the pre-tensioning method precast slab is uniformly provided with self-stress bars at two ends; the inner end of the self-stress bar is anchored in the precast slab concrete; two adjacent pre-tensioning method precast slabs are connected through aligned self-stress bars; expansion concrete is cast in the self-stress joint; the steel strands are arranged along the length direction of the slab, and the arrangement position of the steel strands is 1-2 cm lower than the longitudinal central axis of the pre-tensioning method precast slab. The pre-tensioning method precast slab provided by the application has good quality and long service life.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of highway paving, and particularly relates to a pre-tensioning method precast slab structure for road surface through self-stress joint compensation of slab end stress. BACKGROUND

[0002] Generally, the pre-tensioning method precast slab prestressed tendon is arranged at the bottom of the precast slab, and is used for bearing the live load or static load on the top of the precast slab. In theory, the top concrete of the precast slab is under compression, and the bottom concrete of the precast slab is under tension. However, in the actual application process, due to the combined action of the live load and the temperature stress, the top and bottom concrete of the precast slab for road surface may be under tension or compression. In this case, the top concrete of the precast slab and the bottom concrete of the precast slab may be cracked under excessive tensile stress, which affects the use effect of the road surface.

[0003] In addition, for the precast slab poured by the pre-tensioning method, after the prestressed tendon is tensioned, the prestress in the slab gradually reaches the design value from zero from the end to the inside, and the end stress needs a transfer length. This leads to insufficient stress in the transfer length part of the two ends of the pre-tensioning method precast slab, which is also the main reason for the cracking of the pre-tensioning method precast slab. The cracking of the precast slab causes corrosion of the steel bar and poor durability.

[0004] In the traditional pre-tensioning method precast slab structure, the spiral tendon is prone to deviation, which is also a reason for the cracking of the end concrete of the pre-tensioning method precast slab.

[0005] Therefore, there is an urgent need for a new pre-tensioning method precast slab structure which can significantly reduce the cracking risk of the top and bottom of the precast slab, and effectively avoid the cracking problem of the end of the precast slab. SUMMARY

[0006] In order to overcome the defects in the prior art, the present application provides a pre-tensioning method precast slab structure for road surface through self-stress joint compensation of slab end stress.

[0007] According to one aspect of the present application, a pre-tensioning method precast slab structure for road surface through self-stress joint compensation of slab end stress is provided, which comprises: pre-tensioning method precast slabs 1 arranged at intervals, and a self-stress joint 2 formed between the ends of two adjacent pre-tensioning method precast slabs 1.

[0008] The pre-tensioning method precast slab 1 is composed of precast slab concrete 2, and a plurality of longitudinal steel strands 3 and a plurality of transverse steel bars 13 uniformly arranged in the precast slab concrete 2;

[0009] The equidistantly positioned spiral tendon 5 is poured in the precast slab concrete 2 and fixed on the steel strand 3;

[0010] The self-stress reinforcement 4 is evenly arranged at both ends of the precast slab 1; the inner end of the self-stress reinforcement 4 is anchored in the precast slab concrete 2; two adjacent precast slabs 1 are welded and connected through the aligned self-stress reinforcements 4.

[0011] The self-stress joint is filled with the expansive concrete 7.

[0012] The steel strand 3 is arranged along the length direction of the slab, and the arrangement position of the steel strand 3 is 1-2 cm lower than the longitudinal center axis of the precast slab 1.

[0013] According to one specific embodiment of the present application, one self-stress reinforcement 4 is arranged above and below the end of each steel strand 3, and the two self-stress reinforcements 4 are centrally symmetrically distributed relative to the steel strand 3.

[0014] According to another specific embodiment of the present application, the two ends of the equidistantly positioned spiral reinforcement 5 are the steel reinforcement ring 8 perpendicular to the steel strand 3; the center of the steel reinforcement ring 8 is provided with a nut 9, the nut 9 is fixedly connected with the steel reinforcement ring 8 through a connecting rod 10; the steel strand 3 penetrates and is fixed in the inner hole of the nut 9.

[0015] According to still another specific embodiment of the present application, the nut 9 is fixedly connected with the steel reinforcement ring 8 through three connecting rods 10 with equal length and 120° included angle between each other.

[0016] According to still another specific embodiment of the present application, the transverse steel reinforcement 13 in the precast slab 1 is equidistantly arranged below the steel strand 3.

[0017] According to still another specific embodiment of the present application, the transverse steel reinforcement 13 is a secondary steel reinforcement with a diameter of 16-22 mm, and the spacing between a plurality of transverse steel reinforcements 13 is 50-70 cm.

[0018] According to still another specific embodiment of the present application, the expansive agent content in the expansive concrete 7 is 9%-12%, and the stress generated after expansion is 3-5.5 MPa.

[0019] According to still another specific embodiment of the present application, the length of the self-stress reinforcement 4 anchored in the precast slab 1 is 60-65 cm, and the length of the exposed part is 21-30 cm.

[0020] According to still another specific embodiment of the present application,

[0021] Two self-stress reinforcement stirrups 12 are evenly arranged outside the self-stress reinforcement 4.

[0022] The self-stress reinforcement stirrup 12 is a secondary steel reinforcement with a diameter in the range of 10-12 mm.

[0023] According to still another specific embodiment of the present application,

[0024] The self-stress rib 4 is a secondary steel bar with a diameter of 18-20 mm;

[0025] The welding length of adjacent self-stress ribs 4 is not less than 10 times of the diameter thereof.

[0026] The present application creatively sets the steel strand at 1-2 cm below the middle of the precast slab by pretensioning method. After the tension of the steel strand, the top and bottom concretes of the precast slab by pretensioning method both have certain compressive stress, and the compressive stress of the bottom concrete is slightly greater than that of the top concrete, which is consistent with the actual stress of the pavement slab, thus well solving the problem of concrete cracking caused by excessive tensile stress of the top and bottom concretes of the precast slab by pretensioning method.

[0027] The present application adds a certain proportion of high-efficiency expanding agent into the concrete of the self-stress joint connecting the precast slab by pretensioning method, so as to form the expanding concrete with unique expansion capacity. The expansion of the expanding concrete tension the prestressed rib, and simultaneously stress compensates the end of the precast slab by pretensioning method through the expansion of the self-stress joint, which can effectively avoid the cracking of the end of the precast slab by pretensioning method and ensure the whole precast slab by pretensioning method to reach the design service life requirement.

[0028] In addition, the equidistant positioning spiral rib used in the present application has high stability and is easy to fix compared with the traditional spiral rib, which effectively avoids the cracking of the end concrete caused by the deviation of the spiral steel rib after the tension of the steel strand. BRIEF DESCRIPTION OF DRAWINGS

[0029] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the following drawings:

[0030] Figure 1 Fig. 1 shows a front view of one specific embodiment of the precast slab by pretensioning method for pavement of the present application, which compensates the end stress of the slab through the self-stress joint;

[0031] Figure 2 Fig. 2 shows a left view of the precast slab by pretensioning method of the present application; Figure 1 Fig. 3 shows a left view of the precast slab by pretensioning method of the present application;

[0032] Figure 3 Fig. 4 shows a top view of the precast slab by pretensioning method of the present application; Figure 1 Fig. 5 shows a top view of the precast slab by pretensioning method of the present application;

[0033] Figure 4 Fig. 6 shows a front view of one specific embodiment of the equidistant positioning spiral rib in the present application;

[0034] Figure 5 Fig. 7 shows a front view of one specific embodiment of the equidistant positioning spiral rib in the present application;Figure 4 Figure 4 is a left view of the equidistantly positioned spiral rib.

[0035] The same or similar reference signs in the drawings represent the same or similar components.

[0036] Reference signs are shown as follows:

[0037] 1, precast concrete slab 2, precast concrete slab 3, steel strand 4, self-stressing tendon 5, equidistantly positioned spiral rib 6, self-stressing joint 7, expanded concrete 8, steel ring 9, nut 10, connecting rod 11, building glue 12, self-stressing tendon stirrup 13, transverse steel bar Embodiment

[0038] The disclosure hereafter provides many different embodiments or examples for implementing different structures of the present application. For the purpose of simplicity, the elements and settings of the particular examples below are described. In addition, the present application can repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and / or settings discussed. It should be noted that the components illustrated in the drawings are not necessarily drawn to scale. The present application omits the description of well-known components and processing techniques and processes to avoid unnecessarily obscuring the present application.

[0039] Reference Figure 1 The present application claims a precast concrete slab structure for road surface by self-stressing joint to compensate the stress of slab end, which comprises: precast concrete slabs 1 arranged at intervals, and self-stressing joints 2 formed between the ends of two adjacent precast concrete slabs 1.

[0040] The stress range of the precast concrete slab 1 is between 0.7Mpa and 2.5Mpa, for example, 0.7Mpa, 1.5Mpa or 2.5Mpa.

[0041] Since the precast concrete slab 1 is too long to be transported and installed, and too short to set more self-stressing joints, the economic efficiency is poor, therefore, the longitudinal length of the precast concrete slab 1 ranges from 6.9m to 9.0m, for example, 6.9m, 8.0m or 9.0m. Since the design width of highway and urban road lane is different, in order to take into account various different mainstream lane widths, the transverse width of the precast concrete slab 1 ranges from 3.0m to 4.0m, for example, 3.0m, 3.5m, 3.75m or 4.0m. Preferably, the thickness of the precast concrete slab 1 ranges from 16cm to 24cm, for example, 16cm, 18cm, 20cm, 22cm or 24cm. It is worth noting that the thickness of the precast concrete slab 1 is related to the load level of the highway, and the heavy load traffic takes a large value, and the light load traffic takes a small value.

[0042] Preferably, the self-stress joint 6 is not too narrow to facilitate the arrangement of the self-stress bar 4, the transverse steel bar 13 and the self-stress bar stirrup 12 in the self-stress joint 6, and is not too wide to increase the cost of the high-expansion concrete, thereby significantly increasing the project cost. Therefore, the width of the self-stress joint 6 is set to be 18-22 cm, for example, 18 cm, 20 cm or 22 cm, by comprehensively considering the implementation difficulty and the cost. More preferably, the high-expansion concrete 7 is cast in the self-stress joint 6 to realize the connection between two adjacent precast panels 1 by the pretensioning method and supplement the stress on the two side ends of the precast panels 1.

[0043] Further, the precast panel 1 is composed of the precast panel concrete 2 and a plurality of longitudinal steel strands 3 and a plurality of transverse steel bars 13 uniformly arranged in the precast panel concrete 2.

[0044] The steel strands 3 are arranged along the length direction of the panel, and the arrangement position of the steel strands 3 is 1-2 cm lower than the longitudinal center axis of the precast panel 1. This arrangement mode can make the top and bottom concretes of the panel have certain compressive stress after the steel strands 3 are tensioned, and is more in line with the actual stress condition of the pavement panel, thereby solving the problem of concrete cracking caused by excessive tensile stress of the top and bottom concretes of the panel.

[0045] Preferably, the grade of the precast panel concrete 2 is 40-45 MPa, for example, 40 MPa, 43 MPa or 45 MPa.

[0046] Referring to Figure 3 , considering that the stress on the lower part of the precast panel 1 is greater than that on the upper part, and the overall stress of the panel should be uniform, the transverse steel bars 13 are arranged at equal intervals below the steel strands 3.

[0047] The longitudinal reinforcement ratio of the transverse steel bars 13 is a constant value, and the diameter affects the arrangement interval of the steel bars. If the diameter is thick, the arrangement interval is large, which affects the uniformity of the overall stress of the panel. If the diameter is thin, the arrangement interval is small, which is complicated in construction. Therefore, by comprehensively considering the stress and construction factors, the second-class steel bars with a diameter of 16-22 mm have the best effect, for example, 16 mm, 18 mm or 22 mm. Preferably, the interval between the plurality of transverse steel bars 13 is 50-70 cm, for example, 50 cm, 60 cm or 70 cm.

[0048] The interval between the steel strands 3 is 35-70 cm, for example, 35 cm, 50 cm or 70 cm. More preferably, the diameter of the steel strands 3 is 12.7 mm, and the strength is 1860 MPa.

[0049] Referring to Figures 1-3, only when the self-stress joints 4 are uniformly arranged can the expansion of the expansion concrete 7 in the self-stress joints 6 be uniformly constrained, and the entire self-stress joints 6 can obtain uniform self-stress, so that the double-row self-stress joints 4 are uniformly arranged at both ends of the precast slab 1. Preferably, the self-stress joints 4 are secondary steel bars with diameters of 18mm-20mm, such as 18mm or 20mm.

[0050] The inner ends of the self-stress joints 4 are anchored in the precast slab concrete 2, and the two adjacent precast slabs 1 are connected by the aligned self-stress joints 4. It is worth noting that due to the limitation of space, the connection between the self-stress joints 4 in the self-stress joints 6 can only adopt single-sided welding, and since the minimum length for ensuring the welding quality of the steel bar is 10 times the diameter of the steel bar, the welding length of the adjacent self-stress joints 4 is not less than 10 times the diameter of the self-stress joints 4.

[0051] Preferably, the length of the self-stress joints 4 anchored in the precast slab 1 is 60cm-65cm, such as 60cm, 62cm or 65cm. The length of the exposed part is 21cm-30cm, such as 21cm, 26cm or 30cm.

[0052] More preferably, one self-stress joint 4 is arranged above and below the end of each steel strand 3, and the two self-stress joints 4 are centrally symmetrically distributed with respect to the steel strand 3, as shown in Figure 1 and Figure 2 .

[0053] More specifically, before pouring the self-stress joints 6 between the two adjacent precast slabs 1, the two aligned self-stress joints 4 in the self-stress joints 6 should be welded first, and then the expansion concrete 7 is poured in the self-stress joints 6. During the expansion of the expansion concrete 7, compressive stress will be generated at the ends of the precast slabs 1 on both sides of the self-stress joints 6, which makes up for the insufficient stress at the ends of the precast slabs 1. In order to ensure that the expansion concrete 7 generates sufficient stress, it is required that the compressive stress generated at the ends of the precast slabs 1 after the expansion of the expansion concrete 7 is in the range of 3MPa-5.5MPa.

[0054] After repeated research and multiple tests by the inventor, the content of the expansion agent in the expansion concrete 7 is determined to be 9%-12%, such as 9%, 10% or 12%, so as to ensure that the stress generated after the expansion of the expansion concrete 7 is in the range of 3MPa-5.5MPa.

[0055] Two self-stress reinforcement hoops 12 are uniformly arranged outside the self-stress reinforcement 4. Preferably, the self-stress reinforcement hoop 12 is a secondary reinforcement with a diameter ranging from 10 mm to 12 mm, such as 10 mm, 11 mm or 12 mm.

[0056] The equidistant positioning spiral reinforcement 5 is poured in the precast slab concrete 2 and fixed on the steel strand 3.

[0057] Referring to Figure 4 and Figure 5 , in order to accurately position the steel strand 3 in the precast slab concrete 2, both ends of the equidistant positioning spiral reinforcement 5 are steel reinforcement rings 8 perpendicular to the steel strand 3. The steel reinforcement ring 8 is a ring bent at the end of the equidistant positioning spiral reinforcement 5. The center of the steel reinforcement ring 8 is provided with a nut 9, and the nut 9 is fixedly connected with the steel reinforcement ring 8 through a connecting rod 10, so as to ensure that the inner hole of the nut 9 is coaxial with the equidistant positioning spiral reinforcement 5. The steel strand 3 is inserted into and fixed in the inner hole of the nut 9. Preferably, a building glue 11 is coated in the inner hole of the nut 9, and the steel strand 3 is fixed through the building glue 11.

[0058] The nut 9 is fixedly connected with the steel reinforcement ring 8 through three connecting rods 10 with equal length and an included angle of 120° between each other, so as to ensure that the nut 9 is in the center position of the equidistant positioning spiral reinforcement 5.

[0059] The following describes the precast slab structure provided by the application through specific embodiments:

[0060] The pre-tensioning method precast slab 1 is arranged along the road in the longitudinal direction, so as to reduce the number of joint seams between the slabs as much as possible and improve the driving comfort. Preferably, the size of the pre-tensioning method precast slab 1 is: the length is 6.9 m~9.0 m, the width is 3.0 m~4.0 m, and the thickness is 16 cm~24 cm. The grade of the precast slab concrete 2 is 40~45 MPa.

[0061] The arrangement mode of the self-stress reinforcement 4 ensures that the resultant force formed by the self-stress reinforcement 4 is consistent with the force direction of the steel strand 3. The embedded length in the slab is consistent with the stress transmission length of the steel strand 3 at the slab end, which is the key to compensate for the stress loss of the steel strand 3 at the slab end. Preferably, the width of the self-stress joint 6 is 14 cm~24 cm. The diameter of the self-stress reinforcement 4 is 18 mm~22 mm, the length of the self-stress reinforcement 4 anchored in the pre-tensioning method precast slab 1 is 60 cm~65 cm, the length of the exposed part of the self-stress reinforcement 4 is 21 cm~30 cm, and the welding length of the two aligned self-stress reinforcements 4 is not less than 10 times the diameter.

[0062] The stress of the precast slab 1 by the pretensioning method is adjusted according to the spacing of the steel strands 3. If the spacing between the steel strands 3 is small, the number of the steel strands 3 arranged in the precast slab 1 by the pretensioning method is large, the stress generated is large, the service life of the slab is long, and the cost is high; if the spacing is large, the stress is small, the service life of the slab is short, and the cost is low. In actual arrangement, the best spacing of the steel strands 3 is finally obtained by comprehensively considering the service life and economy of the slab according to the load grade and design life of the road. Preferably, the spacing of the steel strands 3 is 35 cm-70 cm; the diameter of the steel strands 3 is 12.7 mm, and the strength is 1860 MPa. The stress range of the precast slab 1 by the pretensioning method is 0.7 MPa-2.5 MPa.

[0063] The stress of the precast slab 1 by the pretensioning method is adjusted according to the spacing of the steel strands 3. If the spacing between the steel strands 3 is small, the number of the steel strands 3 arranged in the precast slab 1 by the pretensioning method is large, the stress generated is large, the service life of the slab is long, and the cost is high; if the spacing is large, the stress is small, the service life of the slab is short, and the cost is low. In actual arrangement, the best spacing of the steel strands 3 is finally obtained by comprehensively considering the service life and economy of the slab according to the load grade and design life of the road. Preferably, the spacing of the steel strands 3 is 35 cm-70 cm; the diameter of the steel strands 3 is 12.7 mm, and the strength is 1860 MPa. The stress range of the precast slab 1 by the pretensioning method is 0.7 MPa-2.5 MPa.

[0064] The stress of the precast slab 1 by the pretensioning method is adjusted according to the spacing of the steel strands 3. If the spacing between the steel strands 3 is small, the number of the steel strands 3 arranged in the precast slab 1 by the pretensioning method is large, the stress generated is large, the service life of the slab is long, and the cost is high; if the spacing is large, the stress is small, the service life of the slab is short, and the cost is low. In actual arrangement, the best spacing of the steel strands 3 is finally obtained by comprehensively considering the service life and economy of the slab according to the load grade and design life of the road. Preferably, the spacing of the steel strands 3 is 35 cm-70 cm; the diameter of the steel strands 3 is 12.7 mm, and the strength is 1860 MPa. The stress range of the precast slab 1 by the pretensioning method is 0.7 MPa-2.5 MPa.

[0065] Although the example embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims. For example, it will be readily apparent to one of ordinary skill in the art that the order of the process steps can be changed while still remaining within the scope of the application.

[0066] Moreover, the scope of the application is not intended to be limited to particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. Accordingly, the application is not to be limited to particular embodiments described in the specification, as such can vary. The application is also not to be limited to applications specifically recited in the specification and / or claims.

Claims

1. A pre-tensioned precast slab structure for road surface using a self-stressing joint to compensate for end stress, the pre-tensioned precast slab structure comprising: Pre-tensioned precast slabs (1) are spaced apart, and a self-stressing joint (6) is formed between the ends of two adjacent pre-tensioned precast slabs (1). The pre-tensioned precast slab (1) is composed of precast slab concrete (2) and multiple longitudinal steel strands (3) and multiple transverse steel bars (13) evenly distributed in the precast slab concrete (2); Equidistant positioning spiral reinforcement (5) is poured into the precast concrete slab (2) and fixed to the steel strand (3); Self-stressing tendons (4) are evenly provided at both ends of the pre-tensioned precast slab (1); the inner end of the self-stressing tendon (4) is anchored in the precast slab concrete (2); adjacent pre-tensioned precast slabs (1) are welded together by aligned self-stressing tendons (4). Expansive concrete (7) was poured into the self-stressing joint; Its features are, The steel strand (3) is laid along the length of the plate, and the position of the steel strand (3) is 1-2 cm lower than the longitudinal centerline of the pre-tensioned precast plate (1). The two ends of the equidistant positioning spiral bar (5) are steel bar rings (8) perpendicular to the steel strand (3).

2. The pre-tensioned precast slab structure according to claim 1, characterized in that, Each of the steel strands (3) has a self-stressing tendon (4) above and below its end, and the two self-stressing tendons (4) are centrally symmetrically distributed with respect to the steel strands (3).

3. The pre-tensioned precast slab structure according to claim 1, characterized in that, A nut (9) is provided at the center of the steel bar ring (8), and the nut (9) is fixedly connected to the steel bar ring (8) through a connecting rod (10); the steel strand (3) is inserted into and fixed in the inner hole of the nut (9).

4. The pre-tensioned precast slab structure according to claim 3, characterized in that, The nut (9) is fixedly connected to the steel ring (8) by three connecting rods (10) of equal length and with a 120° angle between each pair.

5. The pre-tensioned precast slab structure according to claim 1, characterized in that, The transverse reinforcing bars (13) in the pre-tensioned precast slab (1) are arranged at equal intervals below the steel strands (3).

6. The pre-tensioned precast slab structure according to claim 1, characterized in that, The transverse steel bars (13) are grade II steel bars with a diameter of 16-22mm, and the spacing between multiple transverse steel bars (13) is 50cm-70cm.

7. The pre-tensioned precast slab structure according to claim 1, characterized in that, The expansive concrete (7) contains 9%-12% expansive agent, and the stress generated after expansion is 3MPa-5.5MPa.

8. The pre-tensioned precast slab structure according to claim 1, characterized in that, The length of the self-stressing tendon (4) anchored in the pre-tensioned precast slab (1) is 60cm-65cm, and the length of the exposed part is 21cm-30cm.

9. The pre-tensioned precast slab structure according to claim 1, characterized in that, Two self-stressing tendon stirrups (12) are evenly arranged outside the self-stressing tendon (4); The self-stressing stirrups (12) are grade II steel bars with a diameter range of 10mm-12mm.

10. The pre-tensioned precast slab structure according to claim 1, characterized in that, The self-stressing tendon (4) is a grade II steel bar with a diameter of 18mm-20mm; The welding length of adjacent self-stressing tendons (4) shall not be less than 10 times their diameter.

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