A new tunnel under the highway portal slope protection structure and method

Abstract

The application discloses a new French tunnel underpass highway portal slope protection structure and method, the protection structure comprises: micro pile, anchor cable anchor assembly, transverse H beam and shotcrete, shotcrete and micro pile, anchor cable, anchor, transverse H beam constitute the protection structure of whole slope; the protection method comprises: the establishment micro pile platform; according to the pile hole drilling position on the micro pile platform; the micro pile is made in the pile hole respectively; at least interval one micro pile is installed between the anchor cable respectively, and the adjacent two anchor cables are connected through anchor; the transverse H beam is installed in the anchor cable and the anchor and is away from the slope on one side; the transverse H beam, anchor cable, anchor and micro pile and shotcrete are sprayed through the spraying process.The new French tunnel underpass highway portal slope protection structure and method provided by the application solve the construction problems of the existing engineering, such as the construction difficulty of portal, the self-stabilization difficulty of portal slope.

Description

Technical Field

[0001] This application relates to a novel Italian-made tunnel underpass highway entrance slope protection structure and method, belonging to the technical field of tunnel underpass highway entrance slope support. Background Technology

[0002] The New Italian Method (NIM), or Geotechnical Controlled Deformation Analysis, is a new tunnel excavation concept proposed by Professor Pietro Lunardi based on the New Austrian Tunneling Method (NATM). It aims to achieve safe tunnel excavation by controlling the deformation of the core soil ahead of the tunnel face. NIM tunnels often employ full-face excavation, requiring high levels of control over the deformation of the surrounding rock. Furthermore, when NIM tunnels pass under existing highways, significant deformation of the existing highways may occur. Therefore, support measures are essential to ensure the safety of the tunnel portal excavation and the continued use of the existing highways.

[0003] Construction of tunnels crossing existing highways presents significant risks and challenges, with construction risks and technical management control proving extremely difficult. There are few precedents for tunnels penetrating existing surface structures at their entrances, and compared to conventional tunnel entry boundary constraints, this adds environmental limitations to maintaining the operation of existing highways. Furthermore, the tunnel entrance slope is difficult to stabilize, and construction at the entrance section can have a substantial impact on existing highways. Minimizing the impact of tunnel entry on the existing highway slope is a key challenge in the construction process. Summary of the Invention

[0004] In view of this, this application addresses the issue that existing tunnel portal slopes are difficult to stabilize, and construction at the portal section may significantly impact existing highways. This application proposes a combined micro-steel pipe pile and anchor bolt support structure as a protective structure for tunnel portal slopes, providing a novel protective structure for tunnel portal slopes under highways. The protective structure includes:

[0005] Micropiles are vertically installed next to the tunnel entrance below the highway. Several micropiles are installed at intervals along the highway. Each micropile includes a steel pipe and cement mortar filled inside the steel pipe.

[0006] The steel pipe is vertically inserted into the slope, and several grouting holes are evenly arranged on the steel pipe. Cement mortar is poured into the steel pipe and seeps into the slope around the steel pipe through the grouting holes.

[0007] An anchor cable and anchor assembly includes several anchor cables and several anchors; the anchor cables are respectively disposed between at least one spaced apart micropiles, one end of the anchor cable is fixed in the upslope next to the tunnel entrance, and the other end of the anchor cable extends out of the upslope; the anchors are respectively anchored to the micropiles;

[0008] A transverse H-beam is located on the side of the anchor cable and anchorage facing away from the uphill slope. The transverse H-beam is connected to the micropile, anchor cable, and anchorage respectively.

[0009] A concrete structure, comprising concrete and a steel mesh, wherein the steel mesh is laid on the entire pile-anchor system, and the concrete fills and covers the micropiles, the anchor cables, the anchors, the transverse H-beams, and the steel mesh, wherein the concrete, together with the micropiles, the anchor cables, the anchors, the H-beams, and the steel mesh, constitutes the protective structure of the entire uphill slope.

[0010] A drainage ditch is provided above the protective structure.

[0011] Micropile-anchor support system is used in the construction of "new STMicroelectronics" tunnels due to its advantages such as convenient construction, simple structure and flexible layout. This application provides a method for slope protection at the entrance of a new STMicroelectronics tunnel under a highway, which is used to solve the problem of difficulty in "entering the tunnel" when the tunnel entrance section passes under an existing highway.

[0012] Includes the following steps:

[0013] (1) Establish a micropillar platform;

[0014] (2) Drill pile holes on the micropile platform according to the layout location;

[0015] (3) Micropiles are made in the pile holes respectively;

[0016] (4) Install anchor cables evenly between micropiles, and connect adjacent anchor cables with anchors;

[0017] (5) Install the transverse H-beam on the side of the anchor cable and the anchor facing away from the uphill slope;

[0018] (6) Apply a spray coating process to the transverse H-beam, the anchor cable, the anchorage, and the...

[0019] Shot concrete is sprayed onto the micropiles to complete the construction of the entire slope protection structure.

[0020] Throughout the construction period, the settlement of the existing road surface in the construction area was continuously monitored.

[0021] Preferably, the manufacturing process of the micropiles is as follows:

[0022] First, determine the number of steel pipes based on the depth of the pile hole;

[0023] Secondly, the steel pipes are laid out along the extension direction of the pile hole;

[0024] Then, connect the grouting machine to the end of the steel pipe that extends out of the pile hole, and pour cement mortar into the steel pipe.

[0025] Preferably, the distance between adjacent micropiles is 0.5m to 0.6m;

[0026] The height of the micropiles is the same as the distance from the ground surface to the bottom of the tunnel, and the diameter of the micropiles is 150~180mm;

[0027] The thickness of the steel pipe is 10mm.

[0028] Preferably, two adjacent steel pipes located in the same pile hole are connected by a sleeve.

[0029] Preferably, the water-cement ratio of the cement mortar is less than or equal to 0.5, and the strength grade of the cement mortar is C30.

[0030] Preferably, when injecting cement mortar into the steel pipe, the grouting is completed in one go, and the grouting pressure is 1-3 MPa.

[0031] Preferably, the installation steps of the anchor cable are as follows:

[0032] (1) Drilling anchor cable installation holes between the micropiles spaced apart above;

[0033] (2) Insert the individual anchor cable and the anchor cable grouting pipe into the anchor cable installation hole respectively;

[0034] (3) Grout is injected into the anchor cable installation hole using a grouting machine;

[0035] (4) Tension the anchor cable after the mortar has solidified to 80% of its design strength.

[0036] Preferably, the tensioning of the anchor cable includes:

[0037] First, perform 1-2 pre-tensioning cycles, with the pre-tensioning load level being 0.1-0.2 times the design tension.

[0038] Then, the anchor cable is tensioned in five stages, with the tension loads for each stage being 40%, 60%, 80%, 100%, and 120% of the design tension, respectively, and each stage lasting 10 minutes.

[0039] Preferably, the spraying process includes:

[0040] First, steel mesh is laid on the micropiles, the anchor cables, the anchors, and the transverse H-beams respectively;

[0041] Then, spraying is carried out in sections from bottom to top towards the steel mesh along the extension direction of the micropiles. The spraying operation is completed in multiple layers, with a thickness of 4-6 cm per layer.

[0042] The beneficial effects that this application can produce include:

[0043] 1) The slope protection structure provided in this application adopts a combination of micropiles and anchor cable assemblies.

[0044] The structure is protected by micropile support structure. After the micropile body is made, it is combined with the subsequent anchor cable and anchor assembly to form an integrated structure with concrete, which improves safety performance and reduces the impact of groundwater on the slope. As the slope earthwork protection structure during the excavation of the portal section of the Xinyifa Tunnel, it can greatly enhance the deformation coordination. Combined with steel mesh and shotcrete, it greatly improves the comprehensive performance, has good anti-seepage effect, and can play a very good waterproof role.

[0045] 2) This application provides a novel Italian-made tunnel underpass highway entrance slope protection structure and method.

[0046] This method addresses the challenges of dangerous and difficult tunnel entrance construction, particularly the instability of the tunnel entrance slope. The key to micropile construction lies in ensuring pile quality, primarily through controlling the quality of the borehole and concrete. Key technologies for micropile construction include borehole formation, verticality control of the pile, and concrete pouring techniques. This construction method enables micropile protection at the entrance of underpass tunnels. This application is applicable to the protection of important buildings and roads near various tunnel entrances, ensuring the normal use of adjacent roads and the safety of the underlying tunnel construction. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the slope protection structure of the present invention;

[0048] Figure 2 A schematic diagram showing the location of the slope protection structure and the intercepting ditch;

[0049] Figure 3 This is a schematic diagram of the structure of the micropile of the present invention;

[0050] Figure 4 This is a schematic diagram of the anchor cable structure of the present invention;

[0051] Figure 5 This is a layout diagram of the pile-anchor structure of the present invention;

[0052] Figure 6 This is a diagram showing the layout of monitoring points for this invention;

[0053] Figure 7 This is a flowchart of the present invention;

[0054] Among them: 1-micropile; 2-pile hole; 3-steel pipe; 4-casing; 5-grouting hole; 6-welding; 7-cement mortar; 8-anchor cable; 9-anchor; 10-transverse H-beam; 11-steel mesh; 12-concrete; 13-existing highway; 14-drainage ditch; 15-anchor cable grouting pipe; 16-grouting body; 17-grouting pipe fixer; 18-tunnel pipe roof advanced support; 19-road surface settlement monitoring point. Detailed Implementation

[0055] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0056] Example 1

[0057] According to the appendix Figure 1-3 The diagram illustrates a novel Italian-made tunnel entrance slope protection structure, comprising:

[0058] Micropiles 1 are vertically installed next to the tunnel entrance below the highway. Several micropiles 1 are installed at intervals along the highway. Each micropile 1 includes a steel pipe 3 and cement mortar filled inside the steel pipe 3.

[0059] The steel pipe 3 is vertically inserted into the slope. Several grouting holes 5 are evenly arranged on the steel pipe 3. Cement mortar is poured into the steel pipe 3 and seeps into the slope around the steel pipe through the grouting holes 5.

[0060] An anchor cable assembly includes a plurality of anchor cables 8 and a plurality of anchors 9; the anchor cables 8 are respectively located between at least one spaced micropillar 1, one end of the anchor cable 8 is fixed in the slope next to the tunnel entrance, and the other end of the anchor cable 8 extends out of the slope; the anchors 9 are respectively connected to the extended ends of the adjacent anchor cables 8.

[0061] A transverse H-beam 10 is located on the side of the anchor cable 8 and anchor 9 facing away from the uphill slope. The transverse H-beam 10 is connected to the micropile 1, the anchor cable 8 and the anchor 9 respectively.

[0062] The concrete structure includes concrete 12 and steel mesh 11. The steel mesh is laid on the entire slope. The concrete 12 fills and covers the micropiles 1, the anchor cables 8, the anchors 9, the transverse H-beams 10 and the steel mesh 11. The concrete 12, together with the micropiles 1, the anchor cables 8, the anchors 9 and the transverse H-beams 10, constitutes the protective structure of the entire slope.

[0063] A drainage ditch 14 is provided on the side of the protective structure facing the existing highway 13.

[0064] Example 2

[0065] The basic construction process for this application is as follows:

[0066] Surveying and setting out → Site clearing → Micropile platform excavation → Drilling → Borehole removal → Steel pipe placement → Secondary borehole cleaning → Grouting → Pile formation → Tunnel top drainage ditch construction → Temporary rigid cross-span construction → Excavation construction → Anchor cable construction → Shotcrete → Next cycle of construction, specifically:

[0067] According to the appendix Figure 4-7 The novel Italian method for protecting the slope at the entrance of a tunnel under a highway includes the following steps:

[0068] (1) Establish a micropile platform, which is located at the entrance of the underpass tunnel of the highway.

[0069] At the uphill slope, the steps for establishing the micropile platform include:

[0070] 1) Surveying and setting out to determine the construction site;

[0071] 2) Based on the site conditions, manual labor and excavators were used to level and clean the micropile platform, leveling the micropile platform to the designed site elevation, in preparation for the next step of micropile construction.

[0072] (2) Drill pile holes 2 on the micropile platform according to the layout location; specifically:

[0073] 1) According to the design drawings, mark the position of each micropile on the micropile platform using wooden wedges.

[0074] The wooden wedge is placed at the center of the hole for the micropile to be installed. The drilling should be aligned with the top of the wooden wedge to ensure that the drilling position meets the requirements of the design drawings. Each pile hole is numbered according to the construction drawings. The pile position, pile diameter, spacing, and depth of all pile holes are given in the construction drawings. Before construction, the positions of each micropile to be installed are numbered and marked as a reference for subsequent construction.

[0075] 2) Drilling: Place the multi-functional drill in the designated position, horizontally, to prevent tilting; then...

[0076] The drill rod is hoisted to the side of the drilling rig, and the hole is slowly drilled until it is formed. The diameter of the pile hole 2 is 240mm. The drill rod is connected every 3m until the design depth is reached.

[0077] (3) Micropiles 1 are made in the pile holes 2 respectively;

[0078] 3) Anchor cables 8 are spaced apart between several micropiles 1, wherein the density of the anchor cables 8 is based on...

[0079] according to

[0080] The design strength of the slope protection structure is determined by the following: typically, an anchor cable 8 is installed between every 3 to 5 micropiles 1, and two adjacent anchor cables 8 are connected by an anchor 9.

[0081] (4) Install the transverse H-beam 10 on the side of the anchor cable 8 and the anchor 9 facing away from the uphill slope;

[0082] (5) Apply a spray coating process to the transverse H-beam 10, the anchor cable 8, and the anchor 9.

[0083] Together with the micropiles 1 and shotcrete 12, the entire slope protection structure is constructed.

[0084] During construction, the settlement of the existing road surface in the construction area should be continuously monitored. The layout of road settlement monitoring points 19 should meet the following requirements:

[0085] 1) Monitoring point installation: At the location where the tunnel entrance crosses the original road, 5 monitoring points are set up on the left and right lanes of the original road respectively, with a horizontal spacing of 3m and a longitudinal spacing of 2m, for a total of 20 monitoring points.

[0086] 2) Monitoring frequency: 2 to 3 times a day during the construction period.

[0087] Furthermore, the distance between adjacent micropiles is 0.5m to 0.6m;

[0088] The height of the micropile is the same as the distance from the ground surface to the bottom of the tunnel, that is, the height of the micropile is determined according to the distance from the ground surface to the bottom of the tunnel. The diameter of the micropile is 150~180mm. In one embodiment of this application, the diameter of the micropile is 168.3mm, and the thickness of the steel pipe is 10mm.

[0089] Furthermore, the manufacturing process of the micropiles is as follows:

[0090] First, according to Figure 5 The pile-anchor structure layout diagram determines the depth of pile hole 2 and the number of steel pipes 3;

[0091] Secondly, the steel pipe 3 is laid along the extension direction of the pile hole 2. Then, the grouting machine is connected to the end of the steel pipe 3 that extends out of the pile hole, and cement mortar is injected into the steel pipe 3. The cement mortar injected into the steel pipe 3 penetrates into the slope near the steel pipe through the grouting hole 5, so that the micro pile 1 and the slope become a whole.

[0092] Specifically, after cleaning each pile hole 2, steel pipes 3 are installed inside the pile hole 2. Each steel pipe 3 is inserted into the pile hole 2 in sequence along the extension direction of the pile hole 2. The axis of each steel pipe 3 coincides with the center line of the pile hole 2. The ends of two adjacent steel pipes 3 are connected by a sleeve 4. One end of the steel pipe 3 located at the top of the pile hole 2 extends out of the pile hole 2 and protrudes 200mm above the ground (i.e., the 50mm PVC pipe at the top of the steel pipe protrudes above the ground) to facilitate the connection between the steel pipe 3 and the grouting pipe on the grouting machine. The two ends of the sleeve 4 are respectively connected to the inner wall of the two adjacent steel pipes 3 that are close to each other.

[0093] Furthermore, two adjacent steel pipes located in the same pile hole are connected by a sleeve.

[0094] Furthermore, the water-cement ratio of the cement mortar is less than or equal to 0.5, and the strength grade of the cement mortar is C30.

[0095] Furthermore, when injecting cement mortar into the steel pipe, the grouting is completed in one go, and the grouting pressure is 1-3 MPa.

[0096] Furthermore, the installation steps for the anchor cable are as follows:

[0097] (1) Drill anchor cable installation holes at least one time interval between the micropiles;

[0098] (2) Insert the individual anchor cable and the anchor cable grouting pipe 15 into the anchor cable installation hole respectively;

[0099] (3) Grout is injected into the anchor cable installation hole using a grouting machine;

[0100] (4) Tension the anchor cable after the mortar has solidified to 80% of its design strength.

[0101] Specifically:

[0102] The anchor cables are made of high-strength steel strand with a strength grade of 1860MPa and a diameter of Φ15.24mm. After verifying that the number of anchor cables matches the number of pile holes, each anchor installation hole is cleaned with high-pressure air. Then, the anchor cables are slowly inserted into the bottom of the holes. One end of the anchor grouting pipe 15 is fitted over the anchor cable and inserted into the hole along with it. The other end of the grouting pipe 15 is connected to the grouting machine. The grouting pipe 15 is fixed to the slope using a grouting pipe fixer 17. A distance of 30-50cm should be maintained between the grouting pipe 15 inserted into the hole and the bottom of the hole.

[0103] Then the grouting machine injects mortar into the anchor cable and the anchor cable installation hole through the anchor cable grouting pipe 15. After the injected mortar solidifies, it forms the grouting body 16.

[0104] After the anchor cables are installed, anchorages are installed between two adjacent anchor cables, and the anchorages connect the two adjacent anchor cables respectively.

[0105] Finally, a transverse H-beam (HEA180) is installed on the outside of the anchor cable and anchorage.

[0106] The grouting material used in the anchor cable holes is C30 cement with a maximum water-cement ratio of 0.5. Grouting is carried out from bottom to top at a pressure of not less than 1–2.5 MPa to ensure the anchor cable holes are completely filled. The anchor cables must not be pulled or moved before the mortar has solidified. Tensioning can begin once the solid has reached 80% of its design strength. The tensioning equipment must be calibrated before tensioning to ensure it can meet the prestressing values.

[0107] Furthermore, the tensioning of the anchor cables includes:

[0108] First, perform 1-2 pre-tensioning cycles, with the pre-tensioning load level being 0.1-0.2 times the design tension.

[0109] Then, the anchor cable is tensioned in five stages, with the tension loads for each stage being 40%, 60%, 80%, 100%, and 120% of the design tension, respectively, and each stage lasting 10 minutes.

[0110] Specifically: The anchor cables undergo 1-2 pre-tensioning cycles before formal tensioning, with a load level 0.1-0.2 times the design tension. The anchor cable tension is divided into five levels, each with a load of 40%, 60%, 80%, 100%, and 120% of the design tension, with each level lasting 10 minutes. The elongation of the anchor cable at each level is recorded. Anchor cable displacement values ​​should be recorded at 1, 3, 5, and 10 minutes within each settling time. The loading rate (KN / min) is 50-100. When the tension reaches the final load and deformation stabilizes, the load is unloaded to the locking load, and the anchor cable is locked. The design tension is 60KN.

[0111] Furthermore, the spraying process includes:

[0112] First, steel mesh is laid on the micropiles, anchor cables, anchorages, and transverse H-beams respectively; the mesh spacing of the steel mesh is 15*15cm, and the steel bars are A240 steel bars, ф8.

[0113] Then, spraying is carried out in sections from bottom to top towards the steel mesh along the extension direction of the micropiles, with a spraying thickness of 4~6cm / layer.

[0114] The specific spraying process is as follows:

[0115] Micropile protection uses C20 shotcrete, applied in a wet-mixed state. Before spraying, loose soil and rocks are cleaned from the surface with high-pressure air, and marker nails are embedded to control the thickness of the shotcrete. The spraying operation is completed in layers, with each layer applied sequentially from bottom to top, and each segment not exceeding 6 meters in length. The initial spray thickness is 4-6 cm. Spraying is carried out at an appropriate thickness (4-6 cm / layer), with each subsequent layer applied after the previous layer has solidified.

[0116] In this application, Figure 4 The design drawing of the intercepting ditch 14 is shown. The intercepting ditch 14 is a cast-in-place C25 reinforced concrete rectangular intercepting ditch with a thickness of 20cm, a width of 60cm, and a depth of 60cm. The intercepting ditch 14 is located at the top of the tunnel and is set between the existing highway 13 and the slope protection structure.

[0117] It should be noted that:

[0118] The tunnel involved in this application passes almost vertically below the existing road, and the tunnel entrance is located at a very shallow depth adjacent to the road section. This poses significant challenges to subsequent slope protection at the tunnel entrance, construction of the tunnel portal structure, and tunnel excavation directly beneath the road. Therefore, it is essential to ensure the normal use of the existing road during construction and to prevent any adverse impact on it, thus facilitating the smooth progress of subsequent tunnel construction. Consequently, this application employs a protective construction method combining micropiles and anchor cable support. This method comprehensively considers both the protection of the existing road and the slope protection at the tunnel entrance. It utilizes micropiles combined with anchor cable structures and shotcrete to form a comprehensive protective structure. A drainage ditch is installed above the protective structure, at the tunnel top, to prevent surface water from affecting the protective structure and ensure the safety of the protective slope.

[0119] like Figure 5 As shown, the micropiles are arranged above the entrance of the underpass tunnel, evenly distributed along the existing highway. Figure 6 As shown, the anchor cables are positioned above the pre-support structure 18 of the Xinyifa Tunnel pipe roof. (The reinforcement effect of the soil piled up by the anchor cables also provides some assistance for the construction of the pre-support pipe roof.)

[0120] Figure 7 The diagram shows the layout of existing road surface settlement monitoring points in the pile-anchor support system. The monitoring points are evenly distributed along the two lanes of the existing road, located above the double lanes of the underpass tunnel, between micropile 1 and existing road 13, totaling 20 points.

[0121] This application offers high safety: since there is no large machinery operating site available on the side of the existing highway 13 above the tunnel, a multi-functional drilling rig is used for drilling operations, which not only ensures the normal use of the existing highway but also improves the safety of micropile construction and ensures the safety of grouting.

[0122] High quality: The key technologies for micropiles construction are hole formation, verticality control of the pile, and concrete pouring technology. The various processes in the construction are simple and clear, allowing for quick and effective handling of problems, thereby accelerating the construction progress and ensuring construction quality.

[0123] Lower construction investment: The construction cost of micropile is relatively economical and reasonable. Under the same geological conditions, the project cost during construction is about 40% lower than that of continuous wall and about 20% lower than that of manually excavated piles. This construction method is easy to operate, reduces labor input, reduces labor intensity, and saves construction time.

[0124] Green and environmentally friendly: Compared with ordinary bored piles or underground continuous walls and other maintenance structures, micropiles have the advantages of fast construction speed, low noise, low cost and no pollution, which are beneficial to slope protection projects under various conditions.

[0125] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A novel Italian-style tunnel entrance slope protection structure, characterized in that, A drainage ditch is provided above the protective structure, and the protective structure includes: Micropiles are vertically installed next to the tunnel entrance below the highway. Several micropiles are installed at intervals along the highway. Each micropile includes a steel pipe and cement mortar filled inside the steel pipe. The steel pipe is vertically inserted into the slope, and several grouting holes are evenly arranged on the steel pipe. Cement mortar is poured into the steel pipe and seeps into the grouting holes through them. An anchor cable and anchor assembly includes a plurality of anchor cables and a plurality of anchors; the anchor cables are located at least one time interval between the micropiles, one end of the anchor cable is anchored in the upslope next to the tunnel entrance, and the other end of the anchor cable extends out of the upslope; the anchors are respectively anchored to the micropiles; A transverse H-beam is located on the side of the anchor cable and anchorage facing away from the uphill slope. The transverse H-beam is connected to the micropile, anchor cable, and anchorage respectively. A concrete structure, comprising concrete and a steel mesh, wherein the steel mesh is laid on the entire uphill slope, and the concrete fills and covers the micropiles, the anchor cables, the anchors, the transverse H-beams and the steel mesh, wherein the concrete, together with the micropiles, the anchor cables, the anchors, the H-beams and the steel mesh, constitutes the protective structure of the entire uphill slope. After the micropiles are fabricated, they are integrated with subsequent anchor cables and anchorages to form a single concrete structure. This structure serves as the slope retaining structure during the excavation of the portal section of the New Italian-French Tunnel, allowing for deformation coordination. The tonality is greatly enhanced, and the combined effect of reinforced mesh and shotcrete significantly improves the overall performance.

2. The construction method of the new Italian-style tunnel underpass highway entrance slope protection structure according to claim 1, characterized in that, Includes the following steps: (1) Establish a micropillar platform; (2) Drill pile holes on the micropile platform according to the layout location; (3) Micropiles are made in the pile holes respectively; (4) Install anchor cables evenly between micropiles, and connect adjacent anchor cables with anchors; (5) Install the transverse H-beam on the side of the anchor cable and the anchor facing away from the uphill slope; The entire slope protection structure is constructed by spraying concrete onto the transverse H-beam, the anchor cable, the anchor, and the micropiles using a spraying process. Throughout the entire construction period, the settlement of the existing road surface in the construction area was continuously monitored. The installation steps for the anchor cable are as follows: (1) Drill anchor cable installation holes between at least one micropillar; (2) Insert the individual anchor cable and the anchor cable grouting pipe into the anchor cable installation hole respectively; (3) Grout is injected into the anchor cable installation hole using a grouting machine; (4) Tension the anchor cable after the mortar has solidified to 80% of its design strength; Anchor cable tensioning includes: First, perform 1-2 pre-tensioning cycles, with the pre-tensioning load level being 0.1-0.2 times the design tension. Then, the anchor cable is tensioned in five stages, with the tension loads for each stage being 40%, 60%, 80%, 100%, and 120% of the design tension, respectively, and each stage lasting 10 minutes.

3. The construction method of the new Italian-style tunnel underpass highway entrance slope protection structure according to claim 2, characterized in that, The manufacturing process of the micropiles is as follows: First, determine the number of steel pipes based on the depth of the pile hole; Secondly, the steel pipes are laid out along the extension direction of the pile hole; Then, connect the grouting machine to the end of the steel pipe that extends out of the pile hole, and pour cement mortar into the steel pipe.

4. The construction method of the new Italian-style tunnel underpass highway entrance slope protection structure according to claim 3, characterized in that, The distance between adjacent micropiles is 0.5m to 0.6m; The height of the micropiles is the same as the distance from the ground surface to the bottom of the tunnel, and the diameter of the micropiles is 150~180mm; The thickness of the steel pipe is 10mm.

5. The construction method of the new Italian-style tunnel underpass highway entrance slope protection structure according to claim 4, characterized in that, Two adjacent steel pipes located in the same pile hole are connected by a sleeve.

6. The construction method of the new Italian-style tunnel underpass highway entrance slope protection structure according to claim 4, characterized in that, The water-cement ratio of the cement mortar is less than or equal to 0.5, and the strength grade of the cement mortar is C30.

7. The construction method of the new Italian-style tunnel underpass highway entrance slope protection structure according to claim 3, characterized in that, When injecting cement mortar into the steel pipe, the grouting should be completed in one go, and the grouting pressure should be 1-3 MPa.

8. The construction method of the new Italian-style tunnel underpass highway entrance slope protection structure according to claim 2, characterized in that, The spraying process includes: First, steel mesh is laid on the micropiles, the anchor cables, the anchors, and the transverse H-beams respectively; Then, spraying is carried out in sections from bottom to top towards the steel mesh along the extension direction of the micropiles. The spraying operation is completed in multiple layers, with a thickness of 4-6 cm per layer.

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