A tension-compression composite type PSB expanded head anchor rod

Abstract

The present application belongs to the technical field of underground anti-floating anchor rod, and discloses a tension-compression composite PSB enlarged head anchor rod. In order to solve the problem that the joint of the finished threaded steel bar and the anchoring body is easy to crack, the tension-compression composite PSB enlarged head anchor rod is provided. The finished threaded steel bar comprises an upper finished threaded steel bar, a middle finished threaded steel bar and a lower finished threaded steel bar. The diameter of the middle finished threaded steel bar is greater than that of the upper finished threaded steel bar, and the diameter of the upper finished threaded steel bar is greater than that of the lower finished threaded steel bar. The present application avoids the concentration at the upper end of the middle finished threaded steel bar, thereby improving the stress uniformity between the middle finished threaded steel bar and the anchoring body, making the anchoring body corresponding to the enlarged head section more dispersed and uniform in stress along the length direction, and finally achieving the purpose of reducing the cracking damage of the anchoring body.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underground anti-floating anchor rods, and particularly relates to a tension-compression composite PSB enlarged-head anchor rod. BACKGROUND

[0002] As an anti-floating measure for building structures, the anti-floating anchor rod is connected with the base plate of the building foundation to resist the buoyancy of groundwater on the underground structure of the building and prevent the underground structure from being damaged due to the buoyancy of groundwater.

[0003] The Sichuan Province Technical Standard for Precast Threaded Steel Bar Prestressed Anti-floating Anchor Rod (DBJ51 / T210-2022) came into effect on March 1, 2023. In combination with the attached Figure 1 According to Clause 5.1.3 of the technical standard, the basic structure and configuration of the tension-compression type precast threaded steel bar prestressed anti-floating anchor rod should comply with the following provisions:

[0004] 1. A sleeve is arranged on the non-enlarged head section or the free section of the anchor rod body, and is filled with anticorrosive coating material;

[0005] 2. A bearing body is arranged at the enlarged head section or the bottom of the equal-diameter body, the spacing should not be less than 1.5 m, and the number should not be less than 2, and the flexible sealing ring and the bearing body should be firmly connected with the bar body.

[0006] In combination with the attached Figure 1 to the attached Figure 5 , the size of the tension-compression composite enlarged-head anchor rod used for testing is 7.5 m (length) x 0.2 m (non-enlarged section diameter) x 0.5 m (enlarged section diameter). In order to reveal the stress-strain distribution of the anchor rod during tension, strain gauges are arranged on the anchor rod, and the positions of the strain gauges are at depths of 0.2 m, 0.9 m, 1.6 m, 1.8 m, 2.5 m, 3.2 m and 3.4 m from the bottom of the enlarged head section upwards. That is, the distances from the bottom of the enlarged head section to each strain gauge are 0.2 m, 0.9 m, 1.6 m, 1.8 m, 2.5 m, 3.2 m and 3.4 m respectively. First, polish the steel bar at the strain gauge design position to form a smooth surface, remove the surface dust, and paste the strain gauges thereon. The strain gauge used is type 120-5AA, i.e. the resistance value is 120 Ω and the grid length is 5 mm. When installing the strain gauges, first fix them with 502 glue, then cover them with 704 silicone for insulation, and finally cover them with epoxy resin glue for protection.

[0007] After the construction of the tension-compression composite enlarged-head anchor rod is completed, a jack + counterforce frame is used to apply the pulling force, and a micrometer is used to read the displacement; the steel strain is collected and obtained Figures 3 to 5 by using a static signal acquisition instrument and a notebook computer.

[0008] FromFigures 3 to 5 Analysis of strain data reveals that the strain in the free section of the tension-compression composite enlarged-head anchor bolt remains relatively stable, while the strain in the anchoring section decreases significantly. Stress concentration occurs at the topmost support (i.e., the first support 31), leading to cracking at the variable cross-section. When the pullout load is less than 964 kN (the ultimate load), the strain in the steel bar behind the second support 32 (buried at a depth of 5.9 m) is almost zero, indicating that the precision-rolled threaded steel bar is not effective.

[0009] Therefore, for a tension-compression enlarged head anchor (also known as a tension-compression composite enlarged head anchor), the topmost first load-bearing member is located at the cross-section variation (i.e., the first load-bearing member is located at the intersection of the non-enlarged head section and the enlarged head section of the tension-compression composite enlarged head anchor). However, in practice, tension-compression composite PSB enlarged head anchors are prone to cracking and deformation at the cross-section variation due to stress concentration, which in turn affects the durability and bearing capacity of the anchor. In particular, the presence of through cracks can significantly reduce the durability and bearing capacity of the tension-compression composite enlarged head anchor.

[0010] At the same time, the existing PSB enlarged head anchor rod, when using the fine-rolled threaded steel bars (i.e. PSB) as anchor rod steel bars, uses an integrated structure of the fine-rolled threaded steel bars, that is, the cross-sectional dimensions of the PSB at various positions along the length direction are consistent (leaving aside the influence of the threads), and the bonding force between the PSB and the anchor body mainly relies on the bonding force between the threads on the outer surface of the enlarged head section of the PSB and the anchor body. The junction of the enlarged head section and the non-enlarged head section is the first point of action between the PSB and the anchor body. Since the force at this position is the largest, in addition to causing the anchor body at the variable cross-section to be prone to cracking and deformation, the bonding point between the PSB and the anchor body is also easily damaged. Summary of the Invention

[0011] In order to solve the problem that the junction between the fine-rolled threaded steel bars and the anchor body is prone to cracking, the present invention provides a tension-compression composite PSB enlarged head anchor rod, which avoids concentration at the upper end of the middle section of the fine-rolled threaded steel bars, thereby improving the force uniformity between the middle section of the fine-rolled threaded steel bars and the anchor body, making the anchor body corresponding to the enlarged head section more dispersed and uniform in the length direction, and ultimately achieving the purpose of reducing cracking and damage of the anchor body.

[0012] In order to solve the technical problem, the technical solution adopted by the present invention is:

[0013] A tension and compression combined type PSB enlarged head anchor rod, comprising an anchor hole opened in a stratum, the anchor hole comprising an upper non-enlarged head section and an enlarged head section, a deformed steel bar being arranged in the anchor hole, at least two bearing bodies being arranged on the deformed steel bar and located on the enlarged head section of the anchor hole, and an anchoring body being formed by pouring between the anchor hole and the deformed steel bar, characterized in that the deformed steel bar comprises an upper section deformed steel bar, a middle section deformed steel bar and a lower section deformed steel bar which are connected with each other, the diameter of the middle section deformed steel bar is larger than that of the upper section deformed steel bar, and the diameter of the upper section deformed steel bar is larger than that of the lower section deformed steel bar, and the lower end of the upper section deformed steel bar extends into the enlarged head section of the anchor hole and is connected with the middle section deformed steel bar.

[0014] In some embodiments, the upper section deformed steel bar and the middle section deformed steel bar are connected with each other through a connecting part, the connecting part comprises a connecting part body in a cylindrical shape, the outer surface of the connecting part body is processed to form a threaded section for embedding and connecting with the anchoring body, the inside of the connecting part body is processed to form a stepped through hole, the small diameter section of the stepped through hole is processed to form a threaded hole for threadedly connecting with the upper section deformed steel bar, and the large diameter section of the stepped through hole is processed to form a threaded hole for threadedly connecting with the middle section deformed steel bar.

[0015] In some embodiments, the connecting part body is provided with at least two threaded through holes corresponding to the small diameter section and the large diameter section of the stepped through hole respectively, the lower end of the upper section deformed steel bar and the upper end of the middle section deformed steel bar are provided with through holes corresponding to the threaded through holes respectively, and the threaded through holes and the through holes are provided with a pin shaft.

[0016] In some embodiments, the threaded through holes corresponding to the small diameter section of the stepped through hole are uniformly arranged on the connecting part body, the threaded through holes corresponding to the large diameter section of the stepped through hole are uniformly arranged on the connecting part body, and the two ends of the pin shaft extend out of the connecting part body.

[0017] In some embodiments, the upper end surface of the connecting part body is provided with an annular insertion slot for inserting a sleeve.

[0018] In some embodiments, the bearing body comprises a first bearing body which is the uppermost and located on the enlarged head section of the anchor hole, the first bearing body comprises a threaded cylinder for threadedly connecting with the middle section deformed steel bar, the upper part of the threaded cylinder is provided with a plate, the lower end of the connecting part body and the plate are provided with threaded holes corresponding thereto, the threaded holes are provided with a fastening screw, the first bearing body is sleeved on the middle section deformed steel bar and is fastened with the lower end of the connecting part body, and the plate or the inner wall of the threaded cylinder through hole is provided with a sealing ring.

[0019] In some embodiments, the first carrier body is greater than or equal to h from the intersection of the non-enlarged head section and the enlarged head section of the anchor hole, h is calculated according to the following formula:

[0020] h=tan(45 。 +Ø / 2)*(D2 / 2-d / 2);

[0021] In the above formula, h is the vertical distance of the fracture surface from the variable cross-section position (i.e., the distance between the variable cross-section of the first carrier body and the anchor hole (unit: mm)); Ø is the internal friction angle of the anchor body, which can generally be 35°; D2 is the diameter of the anchor body of the enlarged head section (unit: mm); and d is the diameter of the first carrier body or the pad plate provided with the first carrier body (unit: mm).

[0022] In some embodiments, a pad plate is provided above the first carrier body, the outer diameter of the pad plate is greater than the outer diameter of each carrier body and is adapted to the size of the non-enlarged head section of the anchor hole; or the thickness and outer diameter of the first carrier body are greater than the thickness and outer diameter of the remaining carrier bodies.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) The present application divides the finished threaded steel into upper finished threaded steel, middle finished threaded steel and lower finished threaded steel. In use, the upper finished threaded steel is sleeved with a sleeve, so that there is no binding force between the upper finished threaded steel and the anchor body. The diameter of the middle finished threaded steel is greater than that of the upper finished threaded steel, and the diameter of the upper finished threaded steel is greater than that of the lower finished threaded steel. On the one hand, the contact area between the middle finished threaded steel and the anchor body is larger, thereby improving the binding force between the middle finished threaded steel and the anchor body, avoiding damage and breakage at the contact between the anchor body and the middle finished threaded steel, and improving the anchoring capacity of the anchor rod. On the other hand, the middle finished threaded steel with a larger diameter can transmit and disperse more force downward when an upward force is applied to the finished threaded steel, so that the force along the length direction of the middle finished threaded steel is more dispersed and uniform, avoiding concentration at the upper end of the middle finished threaded steel, thereby improving the force uniformity between the middle finished threaded steel and the anchor body, making the anchor body corresponding to the enlarged head section more dispersed and uniform along the length direction, and finally achieving the purpose of reducing the cracking and damage of the anchor body.

[0025] In summary, the present invention can improve the stress conditions of the anchor body corresponding to the enlarged head section through the structural design of the middle section fine-rolled threaded steel bar with a larger diameter, avoiding the problem of anchor body rupture and damage due to stress concentration; at the same time, it also avoids the problem of damage at the contact point between the anchor body and the middle section fine-rolled threaded steel bar, and ultimately improves the anti-floating ability of the anchor rod.

[0026] (2) In the present invention, the upper section of the fine-rolled threaded steel bar and the middle section of the fine-rolled threaded steel bar are connected by a connecting portion, and the connection between the middle section of the fine-rolled threaded steel bar and the upper section of the fine-rolled threaded steel bar serves as the first point of force, and the diameter of the connecting portion is larger than that of the middle section of the fine-rolled threaded steel bar. Therefore, the connecting portion can further increase the contact area between the anchor body and the anchor body, thereby avoiding crack damage to the anchor body due to stress concentration, thereby improving the durability of the anti-floating anchor rod.

[0027] (3) The present invention utilizes the plate on the first carrier or the sealing ring in the threaded barrel to seal the anti-corrosion grease filled in the step through hole of the connection body. At the same time, the plate of the first carrier is connected to the connection body through a fastening screw. When the force from the upper section of the fine-rolled threaded steel bar is transmitted to the connection body. The connection body transmits part of the force to the middle section of the fine-rolled threaded steel bar, which is then transmitted to the plate of the first carrier; the connection body then directly transmits the other part of the force to the plate of the first carrier through the fastening screw. On the one hand, the force transmitted between the connection body and the middle section of the fine-rolled threaded steel bar is reduced, and on the other hand, the force on the plate is made more uniform, and the force dispersed to the anchor body is also made more uniform, thereby preventing the plate of the first carrier from being easily damaged due to concentrated force. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The structure diagram of the tension and compression type fine-rolled threaded steel bar prestressed anti-floating anchor rod in the prior art is shown in FIG. Figure 1 (a) is a tension-compression type enlarged head anchor rod. Figure 1 (b) is a tension and compression type anchor rod with equal diameter. Figure 1 It can be seen intuitively that the outer diameters of the various carriers are the same;

[0029] Figure 2 Schematic diagram of a loading test for installing strain gauges on an existing compression-resistant composite enlarged head anchor;

[0030] Figure 3 For Figure 2 The strain data of one cycle of the anchor rod during the loading test is shown in the figure. Figure 3 Includes 3a and 3b;

[0031] Figure 4 For Figure 2Another cyclic strain data plot when the anchor rod in the figure 4a is subjected to a load test, Figure 4 Figures 4c and 4d;

[0032] Figure 5 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test, Figure 2 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test, Figure 5 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0033] Figure 6 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0034] Figure 7 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0035] Figure 8 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0036] Figure 9 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0037] Figure 10 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0038] Figure 11 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0039] Figure 12 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0040] Figure 13 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0041] Figure 14 Figures 5e and 5f are another cyclic strain data plot when the anchor rod in the figure 5a is subjected to a load test,

[0042] Marked in the figure: 1, finished threaded steel bar, 101, upper segment finished threaded steel bar, 102, middle segment finished threaded steel bar, 103, lower segment finished threaded steel bar, 2, anchoring body, 3, bearing body, 31, first bearing body, 32, second bearing body, 301, plate, 302, threaded cylinder, 4, flexible sealing ring, 5, sleeve, 6, spiral rib, 7, anchoring pier, 8, prestressed tension locking anchor plate, 9, prestressed tension locking anchor device, 10, anchoring anchor plate, 11, anchoring anchor device, 12, cushion layer, 13, foundation or water-resistant plate, 14, cushion plate, 15, connecting sleeve, 151, sleeve body, 152, upper threaded hole, 153, lower threaded hole, 154, first annular groove, 155, second annular groove, 16, connecting part, 161, connecting part body, 162, stepped through hole, 163, threaded section, 164, threaded through hole, 165, through hole, 166, pin shaft, 167, annular insertion slot, 168, threaded hole, 169, fastening screw. DETAILED DESCRIPTION

[0043] The application will be further described below in conjunction with the embodiments. The described embodiments are only a part of the embodiments of the application, and are not all the embodiments. Based on the embodiments in the application, other embodiments obtained by those skilled in the art without creative work are within the protection scope of the application.

[0044] In the description of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application; the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrated connection; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0045] In conjunction with the drawings Figure 6 to the drawings Figure 10The tension-compression combined PSB expanded head anchor rod of the present application comprises an anchor hole opened in the stratum, the anchor hole comprises a non-expanded head section and an expanded head section from top to bottom, a high-strength deformed steel bar 1 is arranged in the anchor hole, at least two bearing bodies 3 are arranged on the high-strength deformed steel bar 1 and located on the expanded head section of the anchor hole, an anchoring body 2 is formed by pouring between the anchor hole and the high-strength deformed steel bar 1, the high-strength deformed steel bar 1 comprises an upper section high-strength deformed steel bar 101, a middle section high-strength deformed steel bar 102 and a lower section high-strength deformed steel bar 103 which are connected with each other, the diameter of the middle section high-strength deformed steel bar 102 is larger than that of the upper section high-strength deformed steel bar 101, and the diameter of the upper section high-strength deformed steel bar 101 is larger than that of the lower section high-strength deformed steel bar 103, and the lower end of the upper section high-strength deformed steel bar 101 extends into the expanded head section of the anchor hole and is connected with the middle section high-strength deformed steel bar 102.

[0046] In the present application, the high-strength deformed steel bar 1 is divided into an upper section high-strength deformed steel bar, a middle section high-strength deformed steel bar and a lower section high-strength deformed steel bar, in the use process, since the upper section high-strength deformed steel bar is sleeved with a sleeve 5, there is no binding force between the upper section high-strength deformed steel bar 101 and the anchoring body 2; the diameter of the middle section high-strength deformed steel bar 102 is larger than that of the upper section high-strength deformed steel bar 101, and the diameter of the upper section high-strength deformed steel bar 101 is larger than that of the lower section high-strength deformed steel bar 103. On the one hand, the contact area between the middle section high-strength deformed steel bar 102 and the anchoring body 2 is larger, thereby improving the binding force between the middle section high-strength deformed steel bar 102 and the anchoring body 2, so as to avoid damage and breakage at the contact position between the anchoring body 2 and the middle section high-strength deformed steel bar 102, thereby improving the anchoring capacity of the anchor rod; on the other hand, by using the middle section high-strength deformed steel bar 102 with larger diameter, when upward force is applied to the high-strength deformed steel bar 1, the middle section high-strength deformed steel bar 102 with larger size can downwardly transmit and disperse more force, thereby making the force along the length direction of the middle section high-strength deformed steel bar 102 more dispersed and uniform, avoiding concentration at the upper end of the middle section high-strength deformed steel bar 102, thereby improving the force uniformity between the middle section high-strength deformed steel bar 102 and the anchoring body 2, making the anchoring body 2 corresponding to the expanded head section more dispersed and uniform along the length direction, and finally achieving the purpose of reducing the cracking damage of the anchoring body 2.

[0047] In the specific implementation process, the strength of the upper section high-strength deformed steel bar 101 should meet the design requirements, the middle section high-strength deformed steel bar 102 is thickened (for example, a high-strength deformed steel bar with larger diameter is selected) under the premise that the strength of the upper section high-strength deformed steel bar 101 meets the design requirements, thereby making the diameter of the middle section high-strength deformed steel bar 102 larger than that of the upper section high-strength deformed steel bar 101.

[0048] In summary, the present application can improve the stress condition of the anchoring body 2 corresponding to the head section by the structural design of the middle section of the larger diameter finished rolled threaded steel bar 102, avoid the problem of rupture and damage of the anchoring body 2 due to stress concentration, and also avoid the problem of damage of the contact part between the anchoring body 2 and the middle section of the finished rolled threaded steel bar 102, and finally improve the anti-floating capacity of the anchor rod.

[0049] There is also a technical solution in the prior art that uses an extension structure to expand the contact area with the anchoring body 2 (for example, a foldable telescopic structure is provided on the outer periphery of the anchor rod, which can improve the contact area between the anchoring body and the anchor rod after expansion), which can improve the stress condition of the anchoring body to some extent, but the contact part between the anchoring body and the anchor rod does not change, which leads to the fact that the position where the anchoring body and the anchor rod contact each other is prone to crack damage, on the other hand, due to the small size of the anchor rod, plus the effect of the foldable telescopic structure on the expansion and transmission of the force, the anchor rod has a larger force at the installation position corresponding to the installation of the foldable telescopic structure, and a smaller force is transmitted and dispersed along the anchor rod itself (for example, when the anchor rod is not installed with a foldable telescopic structure, the anchor rod itself can transmit a force of N downward, and when the anchor rod is installed with a foldable telescopic structure, the anchor rod itself can transmit a force of M downward, and the size of M is much smaller than N), the reason for this situation is that the foldable telescopic structure directly transmits more force to the anchoring body, resulting in a very small force transmitted downward by the anchor rod itself; the anchor rod is prone to damage or even breakage due to excessive stretching at the position of the installation of the foldable telescopic structure, which is the fundamental reason why this type of anchor rod structure cannot be widely applied in construction engineering.

[0050] In some embodiments, the upper finished rolled threaded steel bar 101 and the middle finished rolled threaded steel bar 102 are connected by the connecting part 16, the connecting part 16 comprises a connecting part body 161 in a cylindrical shape, the outer surface of the connecting part body 161 is processed to form a threaded section 163 for embedding and connecting with the anchoring body 2, the inside of the connecting part body 161 is processed to form a stepped through hole 162, the small-diameter section of the stepped through hole 162 is processed to form a threaded hole for threaded connection with the upper finished rolled threaded steel bar 101, the large-diameter section of the stepped through hole 162 is processed to form a threaded hole for threaded connection with the middle finished rolled threaded steel bar 102; the connecting part body 161 is provided with at least two threaded through holes 164 corresponding to the small-diameter section and the large-diameter section of the stepped through hole respectively, the lower end of the upper finished rolled threaded steel bar 101 and the upper end of the middle finished rolled threaded steel bar 102 are provided with through holes 165 corresponding to the threaded through holes 164, and the threaded through holes 164 and the through holes 165 are provided with a pin shaft 166. The threaded holes of the stepped through hole on the connecting part body are used to directly connect the upper finished rolled threaded steel bar and the middle finished rolled threaded steel bar, and the pin shaft is used for connection, so that the connection of the upper finished rolled threaded steel bar and the middle finished rolled threaded steel bar is realized, and the structure is simple to operate and fast to connect.

[0051] Moreover, the upper finished rolled threaded steel bar 101 and the middle finished rolled threaded steel bar 102 are connected by the connecting part 16, the connection between the middle finished rolled threaded steel bar 102 and the upper finished rolled threaded steel bar 101 serves as the first stress point, and the diameter of the connecting part 16 is larger than that of the middle finished rolled threaded steel bar 102, so that the contact area between the connecting part 16 and the anchoring body 2 can be further increased, the cracking and damage of the anchoring body 2 due to stress concentration can be avoided, and the durability of the anti-floating anchor rod is improved.

[0052] In some embodiments, the threaded through holes 164 corresponding to the small-diameter section of the stepped through hole 162 are uniformly arranged on the connecting part body 161, the threaded through holes 164 corresponding to the large-diameter section of the stepped through hole 162 are uniformly arranged on the connecting part body 161, and the two ends of the pin shaft 166 extend out of the connecting part body 161. As a preferred mode of the present application, two perpendicular threaded through holes are arranged on the connecting part body 161 corresponding to the small-diameter section of the stepped through hole, and two perpendicular threaded through holes are arranged on the connecting part body corresponding to the large-diameter section of the stepped through hole, so that the two pin shafts corresponding to the small-diameter section of the stepped through hole are arranged perpendicularly, and the two pin shafts corresponding to the large-diameter section of the stepped through hole are arranged perpendicularly.

[0053] In the implementation process, the size of the through hole 165 on the upper segment of the finished threaded steel bar 101 is slightly larger than the size of the threaded through hole 164, and the size of the through hole 165 on the middle segment of the finished threaded steel bar 102 is slightly larger than the size of the threaded through hole 164, so as to facilitate the penetration of the pin shaft 166. At the same time, the two ends of the pin shaft 166 extend out of the connecting part body 161, so that the pin shaft 166 can extend into the anchor body 2 formed by pouring, thereby further improving the mutual connection force between the finished threaded steel bar 1 and the anchor body 2.

[0054] In the implementation process, the size of the through hole 165 on the upper segment of the finished threaded steel bar 101 is slightly larger than the size of the threaded through hole 164, and the size of the through hole 165 on the middle segment of the finished threaded steel bar 102 is slightly larger than the size of the threaded through hole 164, so as to facilitate the penetration of the pin shaft 166. At the same time, the two ends of the pin shaft 166 extend out of the connecting part body 161, so that the pin shaft 166 can extend into the anchor body 2 formed by pouring, thereby further improving the mutual connection force between the finished threaded steel bar 1 and the anchor body 2.

[0055] In the implementation process, the size of the through hole 165 on the upper segment of the finished threaded steel bar 101 is slightly larger than the size of the threaded through hole 164, and the size of the through hole 165 on the middle segment of the finished threaded steel bar 102 is slightly larger than the size of the threaded through hole 164, so as to facilitate the penetration of the pin shaft 166. At the same time, the two ends of the pin shaft 166 extend out of the connecting part body 161, so that the pin shaft 166 can extend into the anchor body 2 formed by pouring, thereby further improving the mutual connection force between the finished threaded steel bar 1 and the anchor body 2.

[0056] In the implementation process, the size of the through hole 165 on the upper segment of the finished threaded steel bar 101 is slightly larger than the size of the threaded through hole 164, and the size of the through hole 165 on the middle segment of the finished threaded steel bar 102 is slightly larger than the size of the threaded through hole 164, so as to facilitate the penetration of the pin shaft 166. At the same time, the two ends of the pin shaft 166 extend out of the connecting part body 161, so that the pin shaft 166 can extend into the anchor body 2 formed by pouring, thereby further improving the mutual connection force between the finished threaded steel bar 1 and the anchor body 2.

[0057] In some embodiments, the upper end surface of the connecting part body 161 is provided with an annular insertion slot 167 for inserting the sleeve 5. The sleeve 5 is positioned and stabilized by the annular insertion slot 167 on the connecting part body 161, so as to ensure the stability of the sleeve.

[0058] In some embodiments, the connecting part body 161 is provided with an annular insertion slot 167 for inserting the sleeve 5. The sleeve 5 is positioned and stabilized by the annular insertion slot 167 on the connecting part body 161, so as to ensure the stability of the sleeve. Figure 6 In some embodiments, the connecting part body 161 is provided with an annular insertion slot 167 for inserting the sleeve 5. The sleeve 5 is positioned and stabilized by the annular insertion slot 167 on the connecting part body 161, so as to ensure the stability of the sleeve. Figure 9 In some embodiments, the bearing body 3 includes a first bearing body 31 located at the uppermost position of the enlarged head section of the anchor hole, and the first bearing body 31 includes a threaded cylinder 302 for mutual threaded connection with the middle segment of the finished threaded steel bar 102. The upper end of the threaded cylinder 302 is provided with a plate 301, and the lower end of the connecting part body 161 and the plate 301 are provided with threaded holes 168 corresponding to each other. The threaded holes 168 are provided with fastening screws 169, and the first bearing body 31 is sleeved on the middle segment of the finished threaded steel bar 102 and is fastened to the lower end of the connecting part body 161. The plate 301 or the inner wall of the threaded cylinder through hole is provided with a sealing ring.

[0059] The present application uses the sealing ring in the plate 301 or the threaded cylinder 302 on the first carrier for sealing the anticorrosive grease filled in the stepped through hole of the connecting part body 161, and the plate 301 of the first carrier 31 is connected with the connecting part body 161 through the fastening screw 169. When the force from the upper segment finished rolled threaded steel bar 101 is transmitted to the connecting part body 161, the connecting part body 161 transmits part of the force to the middle segment finished rolled threaded steel bar 102, and the middle segment finished rolled threaded steel bar 102 transmits the force to the plate 301 of the first carrier 31; the connecting part body 161 transmits another part of the force to the plate 301 of the first carrier 31 directly through the fastening screw 169. On the one hand, the force transmitted between the connecting part body 161 and the middle segment finished rolled threaded steel bar 102 is reduced, and on the other hand, the force on the plate 301 is more uniform, so that the force dispersed to the anchoring body 2 is also more uniform, and the problem that the plate 301 of the first carrier 31 is easily damaged due to force concentration is prevented.

[0060] In the prior art, when the anchor rod is pulled upward, the stable force of the plate 301 of the first carrier 31 is all from the anchor rod, which is gradually diffused outward from the contact between the plate and the anchor rod, so that the force is concentrated at the contact between the plate 301 and the anchor rod, and the force concentration will first transmit the force to the anchoring body 2 closest to the force area of the plate, and then cause the area where the anchoring body 2 and the plate 301 first contact to be damaged due to force concentration.

[0061] In the present application, part of the force of the plate 301 is transmitted from the middle segment finished rolled threaded steel bar 102, and another part of the force is transmitted from the fastening screw 169, so that the plate 301 bears force from multiple directions, thereby preventing damage due to force concentration.

[0062] In the specific implementation process, the distance between the first carrier 31 and the intersection of the non-expanded head section and the expanded head section of the anchor hole is greater than or equal to h, and h is calculated according to the following formula:

[0063] h=tan(45 。 +Ø / 2)*(D2 / 2-d / 2);

[0064] In the above formula, h is the vertical distance between the fracture surface and the variable cross-section position of the first bearing body (i.e., the distance between the variable cross-section position of the first bearing body and the anchor hole (unit: mm); is the internal friction angle of the anchor body, which can be 35°; D1 is the diameter of the non-expanded section of the anchor body (unit: mm), D2 is the diameter of the expanded head section of the anchor body (unit: mm); and d is the diameter of the first bearing body 31 or the pad 14 provided with the first bearing body 31 (unit: mm). By changing and determining the position of the first bearing body, compared with the existing technology of the pull-pressure composite expanded head anchor rod (the position of the first bearing body is located at the variable cross-section position, i.e., the intersection of the non-expanded head section and the expanded head section), the position of the first bearing body is changed, which can avoid the problem of anchor body cracking caused by stress concentration, especially avoid the generation of through cracks, and greatly improve the durability and bearing capacity of the expanded head anchor rod.

[0065] In some embodiments, a pad 14 is provided above the first bearing body 31, the outer diameter of the pad 14 is greater than the outer diameter of each bearing body 3 and is adapted to the size of the non-expanded head section of the anchor hole; or the thickness and outer diameter of the first bearing body 31 are greater than the thickness and outer diameter of the remaining bearing bodies 3. In combination with the above Figure 7 and the above Figure 10 When the pad 14 is provided above the first bearing body, the pad 14 is also provided with a threaded hole corresponding to the threaded hole 168 of the connecting portion body 161, and the pad 14 and the connecting portion 16 are fastened and connected by the fastening screw 169.

[0066] In the specific implementation process, the diameter of the plate material 301 of the first bearing body 31 or the pad 14 provided with the plate material 301 of the first bearing body is greater than the outer diameter of the connecting portion 16, so that the connecting portion 16 can improve the contact area with the anchor body 2 to a certain extent, but the force transmission is still mainly relied on the contact between the plate material 301 on the first bearing body 31 or the pad 14 provided with the plate material 301 and the anchor body 2.

[0067] The present application increases the rigidity of the first carrier by arranging a backing plate 14 on the uppermost carrier (i.e. the first carrier 31), and the size of the backing plate is larger than the size of each carrier; or by increasing the outer diameter and the thickness of the first carrier 31. In one aspect, the large size of the backing plate or the thickened first carrier is used to improve the bonding strength between the finished threaded steel bar (commonly known as PSB) and the anchoring body, thereby improving the tensile performance of the anchor rod and the anchoring force of the anchor rod. In another aspect, since the first carrier bears the maximum tensile force, the first carrier is more likely to be damaged due to stress concentration compared to the remaining carriers above and below the finished threaded steel bar. After the first carrier is damaged, the load bearing capacity of the anchor rod is greatly reduced. Therefore, by arranging a backing plate on the first carrier or increasing the thickness and outer diameter of the first carrier, the present application can prevent the first carrier from being damaged, thereby improving the durability and load bearing capacity of the anchor rod.

[0068] The drawings Figure 1 In the prior art, the thickness and size of the uppermost carrier (i.e. the first carrier 31) on the finished threaded steel bar 1 are the same as those of the other carriers. Since the first carrier 31 bears a larger force, it is more likely to be damaged, thereby affecting the durability and load bearing capacity of the anchor rod. Meanwhile, when installing the carriers 3, since the carriers 3 are all threadedly connected to the finished threaded steel bar, the outer thread of the finished threaded steel bar 1 has a large pitch (the pitch is 10-25 mm), and the thickness of the carrier 3 is generally not large (the thickness of the entire carrier (including the plate 301 and the threaded cylinder 302) is generally about 60 mm). Therefore, when installing the carriers 3, it is inevitable that a small eccentricity will occur, and the occurrence of the eccentricity further exacerbates the damage to the first carrier 31.

[0069] The present application uses a backing plate or increases the thickness of the first carrier to improve its own rigidity. At the same time, since the length of the thread connection between the first carrier 31 and the finished threaded steel bar 1 is increased, the probability of the occurrence of the eccentricity of the first carrier 31 is reduced or the degree of the eccentricity is reduced, thereby reducing or avoiding the damage caused by the eccentricity of the carrier 3. Finally, the durability and load bearing capacity of the anchor rod are improved.

[0070] The drawings Figure 11 and the drawings Figure 12 When the diameter of the ordinary section anchoring body is 180 mm, the diameter of the enlarged head section anchoring body is 500 mm, and the diameter of the first carrier 31 or the backing plate 14 is 130 mm, h=355.4 mm is calculated. When the diameter of the first carrier 31 or the backing plate 14 is 150 mm, h=336.2 mm is calculated, and the fracture surface is mainly located in the enlarged head section. Through numerical simulation (please refer to the drawings Figure 13 and the drawings Figure 14), after descending, the anchoring body 2 has cracks with the steel bar section, but due to the large diameter of the expanded head section anchoring body 2, the cracks are not penetrated, and the thickness of the protective layer of the steel bar meets the design requirements.

[0071] In combination with the accompanying drawings Figure 11 and the accompanying drawings Figure 14 , the present application can reduce the problem of stress concentration, reduce the generation of anchoring body 2 cracks, and no through cracks appear, ultimately achieving the purpose of improving the durability and bearing capacity of the anchor rod.

[0072] In some embodiments, the base plate 14 is threadedly connected with the finished threaded steel bar 1 and is in contact with the first carrier 31. In the specific implementation process, a threaded hole that is mutually adapted with the finished threaded steel bar 1 is formed in the middle of the base plate 14, which can realize the installation of the base plate.

[0073] In the specific implementation process, the carrier 3 is generally composed of a threaded cylinder 302 and a plate 301, the threaded cylinder 302 mainly plays a role of threadedly connecting with the finished threaded steel bar 1, and the plate 301 mainly plays a role of transmitting force. Therefore, the plate 301 is located above the threaded cylinder 302. Therefore, the base plate 14 is sleeved on the finished threaded steel bar 1 and is in contact with the plate 301 of the first carrier 31.

[0074] In some embodiments, the carrier 3 further includes a second carrier 32 located below the first carrier 31, the finished threaded steel bar 1 includes a middle finished threaded steel bar 102 and a lower finished threaded steel bar 103, the lower end of the middle finished threaded steel bar 102 passes through the second carrier 32 and is connected with the lower finished threaded steel bar 103, and the outer diameter of the lower finished threaded steel bar 103 is smaller than that of the middle finished threaded steel bar 102.

[0075] In the specific implementation process, the present application first determines the position of the first carrier 31, and then the position of the second carrier 32 (i.e. the distance between adjacent carriers is not less than 1.5 m) can be determined according to the design standard (for example, “Sichuan Province Finished Threaded Steel Bar Prestressed Anti-floating Anchor Rod Technical Standard” (DBJ51 / T210-2022)). Through experiments, it is found that the strain of the finished threaded steel bar 1 located below the second carrier 32 is almost 0, that is, the finished threaded steel bar below the second carrier 32 does not play a role. Therefore, by changing the size of the lower finished threaded steel bar 103, on the one hand, the manufacturing cost is reduced, and on the other hand, the weight of the entire finished threaded steel bar is reduced, which is convenient for transportation and installation, and ultimately achieves the purpose of reducing the construction cost.

[0076] In the application, although the second carrier 32 below the finished rolled threaded steel bar 1 does not displace under the load, the stress is small (the strain is almost 0) and the finished rolled threaded steel bar below the second carrier is not directly sheared off, but the finished rolled threaded steel bar with a smaller diameter is used instead, which is mainly based on the following considerations: first, in the specification design of the anchor rod, the bond strength of the steel bar is checked to ensure that the steel bar will not be pulled out of the anchoring body (generally, in the tension type anchor rod, there is no such problem because the bonding section is long enough, but in the tension-compression type anchor rod, the upper free section is provided with a sleeve, and the overall bonding length of the anchor rod needs to be sufficient). Second, in the specification design of the anchor rod, the anchoring body is checked to ensure that it will not be pulled out of the stratum, so there is a calculation requirement for the overall length of the anchor rod.

[0077] In summary, through the design of the middle section finished rolled threaded steel bar 102 and the lower section finished rolled threaded steel bar 103, and the diameter of the middle section finished rolled threaded steel bar is greater than that of the lower section finished rolled threaded steel bar, the construction cost can be reduced, and at the same time, the design requirements can be met, that is, the bond strength of the steel bar and the bond strength of the anchoring body meet the specification requirements.

[0078] In some embodiments, the middle section finished rolled threaded steel bar 102 and the lower section finished rolled threaded steel bar 103 are connected together by the connecting sleeve 15.

[0079] It should be understood that the above description of the preferred embodiments is more detailed, and therefore should not be considered as limiting the scope of patent protection of the application. Those skilled in the art can make substitutions or modifications under the inspiration of the application without departing from the scope of protection claimed by the application, and all fall within the scope of protection of the application. The scope of protection of the application should be subject to the appended claims.

Claims

1. A tension-compression composite PSB enlarged head anchor rod, comprising an anchor hole opened in a stratum, the anchor hole comprising an upper non-enlarged head section and an enlarged head section, a deformed steel bar (1) being arranged in the anchor hole, at least two load bearing bodies (3) being arranged on the deformed steel bar (1) and located on the enlarged head section of the anchor hole, and an anchoring body (2) being formed by pouring between the anchor hole and the deformed steel bar (1), characterized in that, The finished threaded steel bar (1) comprises an upper finished threaded steel bar (101), a middle finished threaded steel bar (102) and a lower finished threaded steel bar (103) connected with each other, the diameter of the middle finished threaded steel bar (102) is larger than that of the upper finished threaded steel bar (101), the diameter of the upper finished threaded steel bar (101) is larger than that of the lower finished threaded steel bar (103), the lower end of the upper finished threaded steel bar (101) extends into the enlarged head section of the anchor hole and is connected with the middle finished threaded steel bar (102); the upper finished threaded steel bar (101) and the middle finished threaded steel bar (102) are connected with each other through a connecting part (16), the connecting part (16) comprises a connecting part body (161) in a cylindrical shape, the outer surface of the connecting part body (161) is processed to form a threaded section (163) for embedding and connecting with the anchoring body (2), the inside of the connecting part body (161) is processed to form a stepped through hole (162), the small-diameter section of the stepped through hole (162) is processed to form a threaded hole for threaded connection with the upper finished threaded steel bar (101), and the large-diameter section of the stepped through hole (162) is processed to form a threaded hole for threaded connection with the middle finished threaded steel bar (102).

2. The tension and compression composite PSB expanded-head anchor rod according to claim 1, characterized in that, The connecting part body (161) is provided with at least two threaded through holes (164) corresponding to the small-diameter section and the large-diameter section of the stepped through hole (162) respectively, the lower end of the upper finished threaded steel bar (101) and the upper end of the middle finished threaded steel bar (102) are provided with through holes (165) corresponding to the threaded through holes (164), and the threaded through holes (164) and the through holes (165) are provided with a pin shaft (166).

3. The tension-compression composite PSB expanded-head anchor rod according to claim 2, characterized in that, The threaded through holes (164) corresponding to the small-diameter section of the stepped through hole (162) on the connecting part body (161) are uniformly arranged on the connecting part body (161), the threaded through holes (164) corresponding to the large-diameter section of the stepped through hole (162) on the connecting part body (161) are uniformly arranged on the connecting part body (161), and the two ends of the pin shaft (166) extend out of the connecting part body (161).

4. The tension-compression composite PSB expanded-head anchor rod of claim 3, wherein, An annular insertion slot (167) for inserting a sleeve (5) is arranged on the upper end surface of the connecting part body (161).

5. The tension and compression composite PSB expanded-head anchor rod according to claim 4, characterized in that, The bearing body (3) comprises a first bearing body (31) located at the uppermost position of the enlarged head section of the anchor hole, the first bearing body (31) comprises a threaded cylinder (302) for threaded connection with the middle finished threaded steel bar (102), the upper side of the threaded cylinder (302) is provided with a plate (301), threaded holes (168) corresponding to the lower end of the connecting part body (161) and the plate (301) are arranged, a fastening screw (169) is arranged in the threaded holes (168), the first bearing body (31) is sleeved on the middle finished threaded steel bar (102) and is fastened with the lower end of the connecting part body (161), and a sealing ring is arranged on the inner wall of the through hole of the plate (301) or the threaded cylinder (302).

6. The tension and compression composite PSB expanded-head anchor rod according to claim 5, characterized in that, The distance between the first carrier (31) and the intersection of the non-enlarged head section and the enlarged head section of the anchor hole is greater than or equal to h, h is calculated according to the following formula: ； In the above formula, h is the vertical distance from the fracture surface to the position of the variable cross section, is the internal friction angle of the anchor body, D2 is the diameter of the anchor body of the enlarged head section, and d is the diameter of the first carrier or the mat plate matched with the first carrier.

7. The tension-compression composite PSB expanded-head anchor rod according to claim 5 or 6, characterized in that, A mat plate (14) is matched above the first carrier (31), the outer diameter of the mat plate (14) is greater than the outer diameter of each carrier (3) and is matched with the size of the non-enlarged head section of the anchor hole; or the thickness and the outer diameter of the first carrier (31) are greater than the thickness and the outer diameter of the remaining carriers (3).

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