Arch springing expanding type anti-sedimentation supporting cushion of shallow-buried loess tunnel

Abstract

The invention particularly relates to the technical field of tunnel engineering, and discloses an arch springing expanding type anti-sedimentation supporting pad of a shallow-buried loess tunnel, which comprises an arch tunnel, a prefabricated supporting pad is arranged at the arch springing of the arch tunnel, a concrete base is arranged on the prefabricated supporting pad, a mounting part is arranged on the prefabricated supporting pad, and the arch springing expanding type anti-sedimentation supporting pad is arranged on the mounting part. An anchoring part is arranged in the mounting part, a settlement compensation part is connected to the anchoring part, an anti-settlement part is arranged on the settlement compensation part, a pull rope is connected to the anti-settlement part, the number of the prefabricated supporting pads is two, and the prefabricated supporting pads are adopted for load dispersion from an initial surface, oblique anchoring of the anchoring part and creep settlement compensation of the anti-settlement part. And then a three-level anti-sinking defense line is formed through transverse supporting and multi-point anchoring of the settlement compensation part, even if a single mechanism fails, other structures can still play a role, it is ensured that the settlement amount is always controlled within a standard allowable threshold value, and the structure safety in the construction period and the operation period is greatly improved.

Description

Technical Field

[0001] This invention specifically relates to the field of tunnel engineering technology, and more specifically to an arch foot enlarged anti-settlement support for shallow-buried loess tunnels. Background Technology

[0002] As transportation infrastructure projects extend into loess regions, shallow-buried loess tunnels, due to their shallow burial depth and poor surrounding rock stability, have become a key focus of risk control during construction and operation. Among these, the arch foot, as a critical stress transfer node between the tunnel arch and sidewalls, directly bears the vertical loads and lateral pressures transmitted from the arch, and its stability directly determines the overall structural safety of the tunnel. However, loess itself possesses inherent characteristics such as porosity, well-developed vertical joints, high water sensitivity, and weak bearing capacity, making the arch foot of shallow-buried loess tunnels highly susceptible to stress concentration and penetrating settlement, which has become a core technical challenge restricting the construction quality of loess tunnels.

[0003] In existing technologies, conventional solutions for tunnel arch foot support mainly include laying steel plate pads, stacking precast concrete blocks, or setting up temporary steel supports. The core design of these solutions is only to compensate for over-excavation during construction and adjust the elevation of the steel arch frame, failing to fundamentally solve the load transfer problem caused by insufficient bearing capacity of the loess layer. With the deepening of engineering practice, some technical solutions have attempted to reinforce the soil around the arch foot by grouting small pipes or to optimize the installation accuracy by using adjustable pads. However, under conventional support solutions, the settlement of the arch foot generally exceeds the allowable range of the specifications, which not only leads to cracking and water leakage in the tunnel lining structure, but also, in severe cases, causes instability of the arch frame and tunnel collapse, threatening the safety of construction personnel and causing huge economic losses.

[0004] Furthermore, most existing support schemes do not consider the long-term operational stability requirements of shallow-buried loess tunnels. During the operation period, the tunnel arch foot will also be affected by external factors such as changes in groundwater, vehicle vibration, and soil subsidence. The short-term support effect of conventional supports is insufficient to resist soil creep under long-term loads, leading to the continuous development of settlement problems, and subsequent maintenance and reinforcement will be difficult and costly. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an enlarged anti-settlement support for the arch foot of shallow-buried loess tunnels. This solves the problems of small load transfer area, significant stress concentration, insufficient support structure strength, and soil creep caused by external factors in existing tunnel arch foot support technologies, which cannot effectively solve the problem of penetrating settlement of the arch foot of shallow-buried loess tunnels.

[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: an arch foot enlarged anti-settlement support for a shallow-buried loess tunnel, comprising an arched tunnel, a precast support provided at the arch foot of the arched tunnel, a concrete base provided on the precast support, an installation part provided on the precast support, an anchoring part provided in the installation part, a settlement compensation part connected to the anchoring part, an anti-settlement part provided on the settlement compensation part, and a pull rope connected to the anti-settlement part.

[0007] Preferably, there are two precast supports, each precast support is respectively set at one of the two arch feet of the arched tunnel, and each precast support is fixedly connected to the corresponding arch foot of the arched tunnel through a concrete base.

[0008] Preferably, the mounting part includes an arc-shaped groove, which is symmetrically opened on one of the prefabricated supports. The arc surface array of the arc-shaped groove has a sliding groove, and each sliding groove has a rope hole. The prefabricated support has a pile hole corresponding to the rope hole and a sliding hole parallel to the sliding groove.

[0009] Preferably, the anchoring part includes an arc-shaped plate, the arc-shaped plate is made of concrete, the arc-shaped plate is symmetrically inserted into the arc-shaped groove, the arc-shaped plate has an array of guide holes, each of the guide holes is provided with a positioning anchor rod, and the outer arc surface of the arc-shaped plate is provided with a second groove corresponding to the first groove.

[0010] Preferably, the settlement compensation part includes two limiting blocks, which are slidably connected to the inner walls of the first and second sluices on the same side. Each limiting block is elastically connected to the inner wall of the first sluice. A suspension rope with a through-rope hole is fixedly connected to the limiting block. A pile head is slidably connected to the inner wall of the pile hole. The pile head is fixedly connected to the end of the suspension rope. Both sides of the pile head are wedge-shaped structures, and a cut-off head is fixedly connected to the bottom of the pile head.

[0011] Preferably, the number of settlement compensation parts corresponds to the number of slides arranged in the array. The settlement compensation parts are arranged in the corresponding slides, slides, rope holes and pile holes. The arc plate is engaged with the limiting block through slides.

[0012] Preferably, the anti-settlement part includes a sliding arm, which is slidably connected to the inner wall of the sliding hole. Both the sliding arm and the sliding hole are T-shaped structures. A support foot is fixedly connected to the sliding arm, and the support foot is in contact with the prefabricated support pad. A rod hole is opened on the support foot, and a compensating anchor rod is slidably connected in the rod hole. A sliding plate is fixedly connected to one end of the compensating anchor rod, and a tension spring is elastically connected between the sliding plate and the inner wall of the rod hole. A sealing ring is fixedly connected to the inner wall of the opening of the rod hole, and a slit is opened around the sealing ring. The other end of the compensating anchor rod is a conical surface that contacts the sealing ring.

[0013] Preferably, there are two anti-settlement parts, which are symmetrically arranged. The opposite side of the support leg of each of the two anti-settlement parts is a wedge structure and contacts the wedge surface of the pile head. The two ends of the pull rope pass through the support leg and are fixedly connected to the sliding plate of the two anti-settlement parts.

[0014] Preferably, the two anti-settlement parts and the rope form a single-sided anti-settlement mechanism. The number of single-sided anti-settlement mechanisms corresponds to the number of pile heads arranged in the array. The installation part, anchoring part, settlement compensation part, and single-sided anti-settlement mechanism together form a single-sided arch foot enlarged support mechanism. There are two single-sided arch foot enlarged support mechanisms. The other single-sided arch foot enlarged support mechanism is installed on the other prefabricated support pad.

[0015] Preferably, each of the limiting blocks is provided with a pre-positioning hole, and a pre-positioning rod is inserted into each of the pre-positioning holes, the pre-positioning rod abutting against the arc surface of the arc groove.

[0016] (III) Beneficial Effects Compared with the prior art, the present invention provides an arch foot enlarged anti-settlement support for shallow-buried loess tunnels, which has the following beneficial effects: 1. The arch foot enlarged anti-settlement support of this shallow buried loess tunnel adopts prefabricated support to form a three-level anti-settlement defense line, which includes initial surface load distribution, oblique anchoring of the anchoring part, creep settlement compensation of the anti-settlement part, and lateral support and multi-point anchoring of the settlement compensation part. Even if a single mechanism fails, the remaining structures can still play a role, ensuring that the settlement is always controlled within the allowable threshold of the specification, and greatly improving the structural safety during the construction and operation periods.

[0017] 2. The arch foot enlarged anti-settlement support of this shallow-buried loess tunnel adopts a linkage response mechanism between the settlement compensation part and the anti-settlement part. It can sense the creep settlement of the loess layer in real time. Through the graded actions of the arc plate adaptive sinking, the lateral support of the support foot, and the multi-point anchoring of the compensation anchor, the settlement effect is dynamically offset, which solves the defect of existing support that cannot cope with long-term soil creep.

[0018] 3. The arch foot enlarged anti-settlement support pad of this shallow buried loess tunnel adopts a factory prefabrication and on-site assembly and casting mode. It can be adapted to tunnel arch feet of different lengths by splicing multiple support pads. The pre-positioning rod design ensures accurate positioning of components during the construction stage. The installation process is simple and efficient, without complicated procedures, reducing construction costs and difficulties.

[0019] 4. The arch foot enlarged anti-settlement support of this shallow buried loess tunnel adopts a combination design of prefabricated support to expand the contact area, arc plate to disperse stress and anchor rod to diagonally anchor, so as to evenly transfer the concentrated load of the arch foot to a larger area of ​​loess layer, significantly reduce the foundation pressure, and avoid penetrating settlement caused by local pressure exceeding the bearing capacity of loess from the root. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of an enlarged anti-settlement support pad for a shallow-buried loess tunnel proposed in this invention. Figure 2 This is a schematic diagram of the overall bottom structure of the present invention; Figure 3 This is a cross-sectional view of the prefabricated support pad of the present invention; Figure 4 This is a diagram showing the fit between the prefabricated support and the anchoring part of the present invention; Figure 5 This is a top view of the prefabricated support and mounting part of the present invention; Figure 6 This is a bottom view of the prefabricated support and mounting part of the present invention; Figure 7 This is a schematic diagram of the settlement compensation part of the present invention; Figure 8 This is a cross-sectional view of the anti-settlement part of the present invention; Figure 9 This is a schematic diagram of the sealing ring structure of the present invention; Figure 10 This is a diagram showing the fit between the prepositioning rod and the limiting block of the present invention.

[0021] In the diagram: 1. Arched tunnel; 2. Precast support; 3. Concrete base; 4. Installation section; 41. Arc-shaped groove; 42. Slide groove one; 43. Rope hole; 44. Pile hole; 45. Slide hole; 5. Anchoring section; 51. Arc-shaped plate; 52. Guide hole; 53. Positioning anchor rod; 54. Slide groove two; 6. Settlement compensation section; 61. Limiting block; 62. Spring; 63. Lifting rope; 64. Pile head; 65. Cut-off head; 7. Anti-settlement section; 71. Sliding arm; 72. Support leg; 73. Rod hole; 74. Compensating anchor rod; 75. Sliding plate; 76. Tension spring; 77. Sealing ring; 8. Pull rope; 9. Pre-positioning hole; 10. Pre-positioning rod. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 Please see Figure 1 - Figure 9This invention provides an arch foot enlarged anti-settlement support for a shallow buried loess tunnel, comprising an arched tunnel 1, a precast support 2 made of concrete at the arch foot of the arched tunnel 1, a concrete base 3 on the precast support 2, an installation part 4 on the precast support 2, an anchoring part 5 in the installation part 4, a settlement compensation part 6 connected to the anchoring part 5, an anti-settlement part 7 on the settlement compensation part 6, and a pull rope 8 connected to the anti-settlement part 7.

[0024] In this invention, there are two precast support pads 2. By increasing the contact area between the arch foot and the loess layer, the concentrated load is converted into a surface load, reducing the foundation pressure. The two precast support pads 2 are respectively set at the two arch feet of the arched tunnel 1. Each precast support pad 2 is fixedly connected to the corresponding arch foot of the arched tunnel 1 through a concrete base 3. The concrete base 3 realizes a firm connection between the support pad and the tunnel arch foot and the surrounding soil, thus constructing an initial stable support system.

[0025] Furthermore, the installation unit 4 provides precise installation and motion guidance, ensuring coordinated operation of all components, while adapting to the arc-shaped contour of the tunnel arch foot to ensure structural fit. It includes an arc-shaped groove 41, which is symmetrically opened on one of the precast support pads 2. The arc surface array of the arc-shaped groove 41 has a sliding groove 42, and each sliding groove 42 has a rope hole 43. The precast support pad 2 has a pile hole 44 corresponding to the rope hole 43, and a sliding hole 45 parallel to the sliding groove 42.

[0026] Furthermore, the anchoring part 5 disperses the vertical settlement force through the arc-shaped structure, and together with the inclined guide anchor rods, forms an oblique anchoring system, so that the support and the loess layer form an integrated support, which strengthens the structural anti-slip and anti-settlement foundation strength. It includes an arc-shaped plate 51, which is made of concrete. The arc-shaped plate 51 is symmetrically inserted into the arc-shaped groove 41. The arc-shaped plate 51 has an array of guide holes 52, and each guide hole 52 is provided with a positioning anchor rod 53. The outer arc surface of the arc-shaped plate 51 is provided with a second groove 54 corresponding to the first groove 42.

[0027] In this embodiment, the settlement compensation unit 6 dynamically compensates for the settlement caused by soil creep, preventing settlement accumulation. It includes two limiting blocks 61, which are slidably connected to the inner walls of the first chute 42 and the second chute 54 on the same side. Springs 62 are elastically connected between each limiting block 61 and the inner wall of the first chute 42. A suspension rope 63 is fixedly connected to each limiting block 61 through a rope hole 43. A pile head 64 is slidably connected to the inner wall of the pile hole 44, and the pile head 64 is fixedly connected to the end of the suspension rope 63. Both sides of the pile head 64 have wedge-shaped structures. A cutter head 65 is fixedly connected to the bottom of the pile head 64. The cutter head 65 is made of metal and has a cutting edge. The number of settlement compensation parts 6 corresponds to the number of the arrayed chutes 42. The settlement compensation parts 6 are arrayed in the corresponding chutes 42, chutes 54, rope holes 43 and pile holes 44. The arc plate 51 is engaged with the limiting block 61 through the chutes 54. The pile head 64 senses the creep settlement of the soil. The limiting block 61 is pulled by the suspension rope 63 to release the constraint of the arc plate 51, so as to realize the adaptive sinking of the arc plate 51 and the positioning anchor 53.

[0028] It is worth noting that the anti-settlement section 7 constructs a multi-level anti-settlement defense line to curb excessive settlement, including a sliding arm 71. The sliding arm 71 is slidably connected to the inner wall of the sliding hole 45. Both the sliding arm 71 and the sliding hole 45 are T-shaped structures. A support leg 72 is fixedly connected to the sliding arm 71. The support leg 72 is in contact with the prefabricated support pad 2. A rod hole 73 is opened on the support leg 72. A compensating anchor rod 74 is slidably connected in the rod hole 73. A sliding plate 75 is fixedly connected to one end of the compensating anchor rod 74. A tension spring 76 is elastically connected between the sliding plate 75 and the inner wall of the rod hole 73. A sealing ring 77 is fixedly connected to the inner wall of the opening of the rod hole 73. The sealing ring 77 has a slit around it. The other end of the compensating anchor rod 74 is a conical surface that contacts the sealing ring 77. There are two anti-settlement parts 7, which are symmetrically arranged. The opposite side of the support leg 72 in the two anti-settlement parts 7 is a wedge structure that contacts the wedge surface of the pile head 64. With the help of the transmission between the pile head 64 and the wedge surface of the support leg 72, the support leg 72 is pushed to penetrate the loess layer laterally to form lateral support. The two ends of the pull rope 8 pass through the support leg 72 and are fixedly connected to the sliding plate 75 of the two anti-settlement parts 7. The pull rope 8 initially constrains the compensating anchor rod 74 to ensure structural stability during the installation stage.

[0029] It is worth noting that the two anti-settlement parts 7 and the rope 8 form a single-sided anti-settlement mechanism. The number of single-sided anti-settlement mechanisms corresponds to the number of pile heads 64 set in the array. The installation part 4, the anchoring part 5, the settlement compensation part 6, and the single-sided anti-settlement mechanism together form a single-sided arch foot expansion support mechanism. There are two single-sided arch foot expansion support mechanisms. The other single-sided arch foot expansion support mechanism is installed on another prefabricated support pad 2.

[0030] In use, the concrete arc-shaped plate 51 is symmetrically inserted into the arc-shaped groove 41 of the precast support 2. The arc surface of the arc-shaped plate 51 presses against the limiting block 61, causing it to spring into the sliding groove 54 of the arc-shaped plate 51 under the elastic force of the spring 62, thus completing the installation and limiting of the arc-shaped plate 51. Positioning anchors 53 are driven into the loess layer along the guide holes 52 arranged obliquely on the arc-shaped plate 51 to form an oblique anchoring system. This makes the precast support 2, the arc-shaped plate 51 and the loess layer form an integrated support structure, which strengthens the overall strength and anti-slip ability of the structure. The arc-shaped structure of the arc-shaped plate 51 can convert the vertical settlement force of the tunnel arch foot into dispersed stress along the arc surface, further weakening the local stress concentration and improving the adaptability to the load of the loess layer.

[0031] Concrete is poured into the pre-embedded pit to form a concrete base 3, which firmly bonds the precast support 2 with the tunnel arch foot and the surrounding loess layer. By expanding the contact area of ​​the arch foot, the concentrated load of the arch foot is transformed into a surface load and transferred to the foundation, which initially reduces the pressure on the loess layer and alleviates the stress concentration problem.

[0032] During tunnel operation, factors such as changes in groundwater and vehicle vibration cause creep in the loess layer, resulting in softened soil and slight settlement at the arch foot. At this time, the pile head 64, under its own weight, overcomes the elastic resistance of the spring 62 and sinks downward. The lifting rope 63 pulls the limiting block 61 back along the slide groove 42, releasing the limiting constraint on the arc plate 51. Under the action of settlement force, the arc plate 51 sinks adaptively along the arc groove 41, simultaneously driving the positioning anchor rod 53 to penetrate deeper into the loess layer, reconstructing a stable anchor support, dynamically compensating for the settlement caused by soil creep, and preventing the settlement from continuing to develop.

[0033] During the sinking process of the pile head 64, the interaction between its two wedge surfaces and the wedge surfaces of the support foot 72 generates a lateral thrust, which pushes the support foot 72 to drive the sliding arm 71 to slide outward along the T-shaped sliding hole 45. The support foot 72 is laterally embedded into the surrounding loess layer, forming a lateral support structure, which effectively suppresses the vertical settlement trend of the arch foot. At the same time, the metal cutter 65 at the bottom of the pile head 64 cuts the pull rope 8 through the cutting edge, releasing the constraint on the compensating anchor rod 74. The tension spring 76 releases elastic potential energy, pulling the sliding plate 75 to slide in the rod hole 73, pushing the compensating anchor rod 74 to break through the sealing ring 77 with the cut and slide out laterally, penetrating into the loess layer to form multi-point anchoring, further improving the structure's anti-settlement ability and preventing the settlement from exceeding the allowable threshold of the specification.

[0034] Example 2 Please see Figure 1 - Figure 10 The present invention provides an arch foot enlarged anti-settlement support for shallow buried loess tunnels, including a limiting block 61 with a pre-positioning hole 9, and a pre-positioning rod 10 inserted into the pre-positioning hole 9. The pre-positioning rod 10 abuts against the arc surface of the arc groove 41. The pre-positioning rod 10 locks the limiting block 61 during construction to prevent the component from moving prematurely and to ensure installation accuracy and construction safety.

[0035] During use, before construction, a pre-embedded pit matching the precast support 2 is excavated at the arch foot of the shallow-buried loess tunnel. Two precast support pads 2 are placed corresponding to the arch feet on both sides of the tunnel. If the length of the tunnel arch foot needs to be adapted, multiple precast support pads 2 can be spliced ​​together. The pre-positioning rod 10 passes through the pre-positioning hole 9 to lock the limiting block 61 outside the slide groove 42, preventing the limiting block 61 from retracting into the slide groove 42, preventing the self-weight of the pile head 64 from overcoming the elastic force of the spring 62, and thus preventing damage to the precast support pads. When the support 2 is pushed forward, the foot 72 is blocked by the loess after the precast support 2 is embedded. The pile head 64 cannot push the foot 72. At this time, the prepositioning rod 10 is pulled out. The limiting block 61 will not be pulled back into the sliding groove 42 by the pile head 64. The arc plate 51 is inserted into the arc groove 41. The arc surface of the arc plate 51 presses the limiting block 61 and, under the elastic force of the spring 62, causes the limiting block 61 to spring into the sliding groove 54, thereby limiting the installation of the arc plate 51.

[0036] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. An arch-foot enlarged anti-settlement support for a shallow-buried loess tunnel, comprising an arched tunnel (1), characterized in that: The arched tunnel (1) is provided with a precast support (2) at the arch foot. A concrete base (3) is provided on the precast support (2). An installation part (4) for providing precise installation and motion guidance is provided on the precast support (2). An anchoring part (5) for dispersing vertical settlement force is provided in the installation part (4). A settlement compensation part (6) for dynamically compensating the settlement caused by soil creep is connected to the anchoring part (5). An anti-settlement part (7) for curbing excessive settlement is provided on the settlement compensation part (6). A pull rope (8) is connected to the anti-settlement part (7).

2. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 1, characterized in that: There are two precast support pads (2), and the two precast support pads (2) are respectively set at the two arch feet of the arched tunnel (1). Each precast support pad (2) is fixedly connected to the arch foot of the arched tunnel (1) through a concrete base (3).

3. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 2, characterized in that: The installation part (4) includes an arc groove (41), which is symmetrically opened on one of the prefabricated supports (2). The arc surface array of the arc groove (41) is provided with a sliding groove (42). Each sliding groove (42) is provided with a rope hole (43). The prefabricated support (2) is provided with a pile hole (44) corresponding to the rope hole (43). The prefabricated support (2) is provided with a sliding hole (45) parallel to the sliding groove (42).

4. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 3, characterized in that: The anchoring part (5) includes an arc plate (51), which is made of concrete. The arc plate (51) is symmetrically inserted into the arc groove (41). The arc plate (51) is provided with an array of guide holes (52). Each guide hole (52) is provided with a positioning anchor rod (53). The outer arc surface of the arc plate (51) is provided with a second sliding groove (54) corresponding to the first sliding groove (42).

5. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 4, characterized in that: The settlement compensation part (6) includes two limiting blocks (61). The two limiting blocks (61) are slidably connected to the inner walls of the first slide (42) and the second slide (54) on the same side. Each limiting block (61) is elastically connected to the inner wall of the first slide (42). A suspension rope (63) is fixedly connected to the limiting block (61) through the rope hole (43). A pile head (64) is slidably connected to the inner wall of the pile hole (44). The pile head (64) is fixedly connected to the end of the suspension rope (63). Both sides of the pile head (64) are wedge-shaped structures. A cut-off head (65) is fixedly connected to the bottom of the pile head (64).

6. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 5, characterized in that: The number of settlement compensation parts (6) corresponds to the number of slide grooves (42) arranged in the array. The settlement compensation parts (6) are arranged in the corresponding slide grooves (42), slide grooves (54), rope holes (43) and pile holes (44). The arc plate (51) is engaged with the limiting block (61) through slide grooves (54).

7. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 6, characterized in that: The anti-settlement part (7) includes a sliding arm (71), which is slidably connected to the inner wall of the sliding hole (45). Both the sliding arm (71) and the sliding hole (45) are T-shaped structures. A support leg (72) is fixedly connected to the sliding arm (71). The support leg (72) is in contact with the prefabricated support pad (2). A rod hole (73) is opened on the support leg (72). A compensating anchor rod (74) is slidably connected in the rod hole (73). A sliding plate (75) is fixedly connected to one end of the compensating anchor rod (74). A tension spring (76) is elastically connected between the sliding plate (75) and the inner wall of the rod hole (73). A sealing ring (77) is fixedly connected to the inner wall of the opening of the rod hole (73). A notch is opened around the sealing ring (77). The other end of the compensating anchor rod (74) is a conical surface and contacts the sealing ring (77).

8. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 7, characterized in that: There are two anti-settlement parts (7), and the two anti-settlement parts (7) are arranged symmetrically to each other. The opposite side of the support (72) of the two anti-settlement parts (7) is a wedge structure and contacts the wedge surface of the pile head (64). The two ends of the pull rope (8) pass through the support (72) and are fixedly connected to the sliding plate (75) of the two anti-settlement parts (7).

9. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 8, characterized in that: Two of the anti-settlement parts (7) and the rope (8) form a single-sided anti-settlement mechanism. The number of the single-sided anti-settlement mechanisms corresponds to the number of pile heads (64) arranged in the array. The installation part (4), the anchoring part (5), the settlement compensation part (6), and the single-sided anti-settlement mechanism together form a single-sided arch foot expansion support mechanism. There are two single-sided arch foot expansion support mechanisms. The other single-sided arch foot expansion support mechanism is installed on the other prefabricated support pad (2).

10. The arch foot enlarged anti-settlement support for a shallow-buried loess tunnel according to claim 9, characterized in that: Each of the limiting blocks (61) is provided with a pre-positioning hole (9), and a pre-positioning rod (10) is inserted into each of the pre-positioning holes (9). The pre-positioning rod (10) abuts against the arc surface of the arc groove (41).

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