Anti-falling block double-lining trolley arch foot structure
By creating an inner tangent and setting an isolation groove at the end of the arch foot formwork of the secondary lining trolley, the problem of concrete falling off at the arch foot of the traditional secondary lining trolley was solved, improving the safety and efficiency of tunnel construction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG ROAD & BRIDGE CONSTR
- Filing Date
- 2025-06-10
- Publication Date
- 2026-06-12
Smart Images
Figure CN224351966U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of tunnel construction technology, specifically relating to a secondary lining trolley arch foot structure for preventing block falling. Background Technology
[0002] Secondary lining in tunnel engineering is a core component ensuring the stability and durability of the tunnel structure, and its construction quality directly affects the tunnel's load-bearing capacity and service life. The secondary lining trolley, as a key piece of equipment for integrating concrete pouring, molding, and demolding, must meet the requirements of high-precision positioning, efficient demolding, and adaptability to complex tunnel cross-sections. Currently, secondary lining trolleys generally adopt hydraulic drive and modular template design, using multiple sets of hydraulic cylinders to synchronously extend and retract the template to adapt to construction needs under different surrounding rock conditions.
[0003] However, while high construction precision has been achieved in areas such as the arch crown and sidewalls, construction defects at the arch foot (i.e., the connection between the bottom of the tunnel lining and the invert arch) remain prominent. Traditional secondary lining trolleys, such as the multi-functional secondary lining trolley disclosed in patent CN203308472U, are currently the most common secondary lining trolley structure. The arch wall is typically a monolithic steel wall corresponding to the tunnel's arc, with a uniform thickness from the arch crown to the arch foot, thus forming a uniformly thick concrete wall outside the arch after concrete pouring. However, during conventional secondary lining construction, cracks frequently appear in the concrete at the arch foot after the trolley is demolded, and even concrete spalling occurs. Even manual repair of the spalled areas is inefficient, and the repaired areas have performance differences from the original concrete, easily leading to secondary problems such as water seepage and spalling in the long term. Therefore, spalling at the arch foot during secondary lining construction has become a major bottleneck restricting tunnel construction efficiency and structural safety. Utility Model Content
[0004] The present invention aims to overcome the defect in the prior art where concrete blocks easily fall off at the arch foot during the demolding process of the secondary lining trolley, and provides a secondary lining trolley arch foot structure that prevents concrete blocks from falling off.
[0005] To achieve the above objectives, this utility model is implemented through the following technical solution:
[0006] A secondary lining trolley arch foot structure for preventing block falling includes an arch foot hanging mold. The arch foot hanging mold has an inner tangential surface that contracts towards the trolley side, so that a receiving space for accommodating concrete is formed at the contraction point of the arch foot hanging mold.
[0007] In tunnel construction, the arch walls of the secondary lining trolleys are typically integral steel walls that correspond to the tunnel's arc shape. The thickness of this steel wall is uniform from the arch crown to the arch foot, and the same supporting steel is often used at the arch foot as in other areas. When concrete is poured between the secondary lining trolley and the tunnel, the arch foot, as a stress concentration area of the tunnel lining, must simultaneously bear the dual effects of the upper lining load and the surrounding rock pressure. When shrinkage occurs during concrete solidification or when disturbed by external loads, localized stress concentrations easily occur at the interface between the arch foot formwork and the concrete. After demolding, micro-cracks are very likely to form at the interface, which can further lead to concrete spalling.
[0008] Therefore, this invention optimizes the arch foot section based on the traditional secondary lining trolley. In this invention, the end of the arch foot formwork of the traditional secondary lining trolley is cut towards the trolley, creating an inner slit at the end of the formwork and forming a space to accommodate concrete. After concrete pouring, a strip of concrete is formed at the end of the arch foot formwork, contacting both the ground and the formwork, unlike with the traditional lining trolley. This strip of concrete effectively increases the thickness of the concrete layer at the arch foot, resulting in a tighter bond between the concrete sections and reducing the likelihood of spalling. More importantly, because the concrete here is in direct contact with the ground and the formwork, a portion of the upper lining load is transferred to the ground, reducing stress concentration at the interface between the formwork and the concrete, thus reducing the formation of microcracks and preventing spalling during demolding.
[0009] Preferably, the inner tangential surface is provided with an isolation groove extending along the long side of the trolley. Because the concrete and the arch foot formwork are tightly bonded during pouring, a certain adhesive force exists between them. If the arch foot formwork suddenly separates from the concrete at this time, stress release can easily occur at the interface, potentially causing the concrete to crack. Therefore, this invention provides an isolation groove on the inner tangential surface. On the one hand, due to the inherent viscosity of the concrete, a micro-air layer easily forms within the isolation groove during pouring, reducing direct contact between the concrete and the arch foot formwork. On the other hand, during demolding, the isolation groove allows air to quickly enter the contact surface, eliminating the vacuum adsorption effect and preventing some concrete from adhering to the arch foot formwork during demolding.
[0010] As a further preferred embodiment, the inner tangential surface is provided with two or more isolation grooves with triangular cross-sections.
[0011] As a further preferred embodiment, the inner tangential surface is provided with an isolation groove having an inwardly concave rectangular cross-section.
[0012] As a further preferred embodiment, the isolation groove is embedded with an elastic pad, which protrudes from the inner tangential surface. When using concrete with a fast setting speed, an elastic pad made of elastic material can be embedded in the isolation groove, with a small portion of the elastic pad protruding from the inner tangential surface. When the concrete rapidly sets within the containment space, pressure is applied to the elastic pad; when demolding, the elastic pad releases stress, using its deformation capacity to buffer the tensile force during demolding and prevent the strip of concrete from being forcibly peeled off.
[0013] Preferably, the inner tangential surface has two or more isolation holes. In practice, a series of concave isolation holes can be set on the inner tangential surface along the extension direction of the trolley arch wall, thereby reducing the direct contact between the concrete and the arch foot formwork.
[0014] As a further preferred embodiment, the arch foot formwork is provided with a through-hole for ventilation, which is connected to the isolation holes. In practice, a small-diameter ventilation hole can be set inside the arch foot formwork. When pouring concrete, the two ends of the ventilation hole are sealed to prevent concrete from entering. During demolding, air can be briefly blown from the ventilation hole into the isolation holes to actively break the adhesion between the concrete and the arch foot formwork.
[0015] Preferably, the arch foot formwork is equipped with a template connected to it via a rotating shaft. The template rotates towards the trolley to form the receiving space. During concrete pouring, the angle of the template is first fixed. During demolding, the rotatable template enables segmented demolding. First, the template is slowly rotated inward to demold the strip of concrete, and then other parts are demolded to prevent concrete from falling off due to excessive force.
[0016] As a further preferred embodiment, the template surface is provided with serrated grooves. Through the serrated grooves, air is guided into the contact surface when the strip concrete strip is demolded, forming an air film isolation layer, which reduces the adhesion between the template and the concrete at this point.
[0017] As a further preferred embodiment, a pneumatic rod is provided between the template and the arch foot formwork to restrict the rotation of the template. The rotation angle of the template is manually controlled by the pneumatic rod, while preventing the template from rotating during concrete pouring.
[0018] Therefore, this utility model has the following beneficial effects:
[0019] (1) This utility model improves the arch foot of the traditional secondary lining trolley by forming a strip of concrete at the end of the arch foot formwork that is in contact with the ground and the arch foot formwork at the same time, thereby reducing the occurrence of arch foot block falling off during demolding.
[0020] (2) By setting the isolation groove in the preferred scheme, this utility model further reduces the bonding force between the arch foot formwork and the concrete, and reduces the falling of blocks caused by the movement of the arch foot formwork.
[0021] (3) This utility model has a simple structure. Based on the traditional secondary lining trolley, it can be simply processed to effectively solve the problem of arch foot falling off during tunnel construction. It is suitable for promotion in practice. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the position of the arch foot structure of the anti-falling block trolley in Embodiment 1 of this utility model.
[0023] Figure 2 This is a schematic diagram of the arch foot structure of a secondary lining trolley for preventing block falling, according to Embodiment 1 of this utility model.
[0024] Figure 3 This is a schematic diagram of the arch foot structure of a secondary lining trolley for preventing block falling, according to Embodiment 2 of this utility model.
[0025] Figure 4 This is a schematic diagram of the arch foot structure of a secondary lining trolley for preventing block falling, according to Embodiment 3 of this utility model.
[0026] Figure 5 This is a schematic diagram of the arch foot structure of the secondary lining trolley for preventing block falling, according to Embodiment 4 of this utility model.
[0027] Figure 6 This is a schematic diagram of the installation of a secondary lining trolley arch foot structure for preventing block falling, according to Embodiment 5 of this utility model.
[0028] In the figure: arch foot hanging formwork 10; rotating shaft 11; template 12; pneumatic rod 13; inner slit 20; isolation groove 21; elastic pad 22; accommodating space 30; isolation hole 40; air duct 41. Detailed Implementation
[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only a part of the embodiments of the present invention, and not all of the embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.
[0030] Example 1:
[0031] like Figure 1 , 2As shown, this embodiment illustrates an anti-slab-falling arch foot structure for the secondary lining trolley, located at the lower end of the secondary lining trolley's steel wall. In this embodiment, the arch foot formwork 10 is cut 50mm from its very end. The arch foot formwork 10 has a thickness of 12mm, with a 2mm allowance at the bottom. The cutting height is 20mm, and the chamfer radius is 10mm. By cutting the arch foot formwork 10, an inner cleaved surface 20 is formed on the cut surface, and the removed portion of the arch foot formwork 10 becomes the receiving space 30. During concrete pouring, the concrete enters the receiving space 30, forming a strip of concrete extending along the tunnel direction. When the concrete solidifies and is demolded, the presence of this strip of concrete reduces the occurrence of slab-falling.
[0032] Example 2:
[0033] like Figure 3 As shown, this embodiment of the anti-sharding secondary lining trolley arch foot structure differs from Embodiment 1 in that: in this embodiment, three parallel isolation grooves 21 are chiseled on the inner lining 20, and the cross-section of the isolation grooves 21 is triangular. During concrete pouring, the concrete enters the receiving space 30. Due to the viscosity of the concrete, it does not immediately fill the entire isolation groove 21, but instead forms multiple tiny air pockets at the isolation groove 21. Overall, this forms a gas isolation layer on the entire inner lining 20 to isolate the inner lining 20 and the concrete, reducing the adhesion between them. When the arch foot formwork 10 is removed from the concrete for demolding, external gas can quickly enter between the inner lining 20 and the concrete along the isolation grooves 21, thereby preventing sharding caused by concrete adhesion.
[0034] Example 3:
[0035] like Figure 4 As shown, this embodiment of the anti-sharding secondary lining trolley arch foot structure differs from Embodiment 1 in that: in this embodiment, an isolation groove 21 is chiseled on the inner tangent 20. The cross-section of the isolation groove 21 is rectangular, and an elastic pad 22 protruding 2mm from the inner tangent is embedded in the isolation groove 21. When using quick-setting concrete for pouring, as the concrete enters the receiving space 30, the concrete quickly sets and applies a certain pressure to the elastic pad 22, causing the elastic pad 22 to contract inward. During demolding, when the arch foot formwork 10 moves away from the concrete, the elastic pad 22 releases the compressive stress and uses its deformation capacity to buffer the tensile force during demolding, preventing the strip of concrete from being forcibly peeled off. At the same time, the elastic pad 22 can act as a buffer between the arch foot formwork 10 and the solidified concrete, reducing the direct impact on the concrete strip during the trolley's displacement, thereby achieving the purpose of preventing sharding.
[0036] Example 4:
[0037] like Figure 5As shown, this embodiment of the anti-slab-falling secondary lining trolley arch foot structure differs from Embodiment 1 in that: in this embodiment, a series of isolation holes 40 are set at 5mm intervals along the extension direction of the trolley on the inner tangential surface 20, and all isolation holes 40 are connected at the end of the arch foot hanging mold 10 through a through-hole vent 41, thereby forming an active gas isolation structure. During concrete pouring, the vent vents 41 on both sides are first sealed, so that concrete cannot enter the isolation holes 40 in small quantities under air pressure; when demolding is required after the concrete has solidified, the vent vent 41 is opened, and air is blown into the vent vent 41 on one side using an industrial blower, while simultaneously moving the arch foot hanging mold 10 away from the concrete wall. Because the adsorption between the concrete and the arch foot hanging mold 10 is broken by the rapidly moving gas, the probability of slab falling is further reduced.
[0038] Example 5:
[0039] like Figure 6 As shown, the arch foot structure of the anti-falling liner trolley in this embodiment differs from that in Embodiment 1 in that: the end of the arch foot hanging mold 10 in this embodiment has an L-shaped structure. A series of rotating shafts 11 are arranged at the short end of the L-shaped structure along the extension direction of the trolley. These rotating shafts 11 are connected to a whole template 12, allowing the template 12 to rotate around the rotating shafts 11. Furthermore, the surface of the template is provided with serrated grooves. At the same time, a pneumatic rod 13 is also provided between the template 12 and the arch foot hanging mold 10 to connect the two. The pressure of the pneumatic rod 13 and the friction between the template 12 and the rotating shafts 11 can be used to fix the template 12 at a specific angle. During concrete pouring, the formwork 12 is first fixed at the target angle, creating a receiving space 30 on the side of the formwork 12 away from the arch foot formwork 10. After the concrete enters the receiving space 30, it forms a strip of concrete. During demolding, the angle of the formwork 12 is slowly adjusted under the action of the pneumatic rod 13, allowing the formwork 12 to slowly separate from the concrete. At this time, air is guided into the contact surface through the serrated grooves to facilitate the separation of the formwork 12. After the formwork 12 is completely separated from the concrete, the trolley is moved to demold other locations. Even if the trolley applies a large pulling force to other locations, it will not affect the concrete strip at the arch foot, thus reducing the occurrence of sharding.
[0040] The embodiments of this specification have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technological improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A secondary lining trolley arch foot structure for preventing block falling, characterized in that: Includes an arch foot formwork (10), which has an inner tangent (20) that tapers toward the trolley side, such that a receiving space (30) for receiving concrete is formed at the tapping point of the arch foot formwork (10).
2. The anti-falling block secondary lining trolley arch foot structure according to claim 1, characterized in that: The inner tangential surface (20) is provided with an isolation groove (21) extending along the long side of the trolley.
3. The anti-falling block secondary lining trolley arch foot structure according to claim 2, characterized in that: The inner tangent (20) is provided with two or more isolation grooves (21) with triangular cross sections.
4. The anti-falling block secondary lining trolley arch foot structure according to claim 2, characterized in that: The inner tangent (20) is provided with an isolation groove (21) with an inwardly concave rectangular cross-section.
5. The anti-falling block secondary lining trolley arch foot structure according to claim 4, characterized in that: The isolation groove (21) is embedded with an elastic pad (22), such that the elastic pad (22) protrudes from the inner tangent surface (20).
6. The anti-falling block secondary lining trolley arch foot structure according to claim 1, characterized in that: The inner tangent (20) is provided with two or more isolation holes (40).
7. The anti-falling block secondary lining trolley arch foot structure according to claim 6, characterized in that: The arch foot hanging mold (10) is provided with a through air guide hole (41), which is connected to the isolation hole (40).
8. The anti-falling block secondary lining trolley arch foot structure according to claim 1, characterized in that: The arch foot hanging mold (10) is provided with a template (12) rotatably connected by a rotating shaft (11), and the template (12) rotates toward the trolley to form the accommodating space (30).
9. The anti-falling block secondary lining trolley arch foot structure according to claim 8, characterized in that: The template (12) has a serrated groove on its surface.
10. The anti-falling block secondary lining trolley arch foot structure according to claim 8, characterized in that: A pneumatic rod (13) is provided between the template (12) and the arch foot hanging mold (10) to restrict the rotation of the template (12).