Ultra-large karst cave arch protection structure of highway tunnel

Abstract

The utility model discloses a highway tunnel ultra-large type karst cave arch protection structure which comprises a protection arch and a buffer layer above the protection arch, the buffer layer comprises enclosure areas and a sand filling area, the enclosure areas are arranged on the two sides of the protection arch, the sand filling area is formed between the two enclosure areas, sand is filled in the sand filling area, a plurality of layers of sand bags are arranged in the enclosure areas along the arch face of the protection arch, and the sand bags are filled with sand. The sand and the sand bags jointly provide buffering for the protection arch. According to the arch protection structure, sand filled in the upper portion is blocked through the sand bags, and the problem that sand on the top slides off is effectively solved while the buffering performance is guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of tunnel construction technology, specifically to a support arch structure for an ultra-large karst cave in a highway tunnel. Background Technology

[0002] Highways are gradually replacing rugged mountain roads. When constructing highway tunnels in karst mountainous areas, the treatment of karst caves has become a hot topic. Ensuring the rationality and economy of treatment measures is of great significance. Karst caves have complex spatial structures, often accompanied by numerous cavities in their upper parts. To prevent debris from falling from the cave ceiling and damaging the tunnel structure, a sand buffer layer is typically laid on top of the arch support, as described in CN108547643A, which discloses a construction method for treating large cavities in the tunnel ceiling. However, this sand buffer layer is prone to landslides, affecting construction progress. Utility Model Content

[0003] To address the aforementioned problems, this utility model provides an ultra-large karst cave arch support structure for highway tunnels, which can effectively solve the landslide problem of sand buffer layer and ensure the normal progress of construction.

[0004] Specifically, this utility model is implemented as follows:

[0005] A protective arch structure for a super-large karst cave in a highway tunnel, comprising a protective arch and a buffer layer above the protective arch, wherein the buffer layer comprises:

[0006] The enclosure is set on both sides of the arch, and a sand-filled area is formed between the two enclosures. The sand-filled area is filled with sand, and several layers of sandbags are arranged along the arch surface of the arch in the enclosure.

[0007] The sandbags in adjacent layers are arranged alternately.

[0008] The protected area is equipped with barriers to restrict the sandbags and prevent them from slipping.

[0009] The blocking component is a blocking strip, and multiple blocking strips are arranged along the circumference of the arch support. The blocking strips are arranged in a direction parallel to the axis of the arch support, and the sandbags are arranged between two adjacent blocking strips.

[0010] The blocking element is a blocking block, and the blocking blocks are arranged at intervals along a direction parallel to the axis of the protective arch;

[0011] The blocking blocks are arranged in several layers, and the sandbags are arranged between adjacent blocking blocks.

[0012] The blocking element is a woven strip, which is arranged in a crisscross pattern to form several filling areas, and the sandbag is placed in the filling area.

[0013] Compared with the prior art, the working principle and beneficial effects of this utility model are as follows:

[0014] (1) The super-large karst cave arch structure for highway tunnels provided by this utility model uses sandbags to block the arch on both sides, and is equipped with blocking components to protect and block the sandbags, which effectively solves the problem of sand slipping off the top.

[0015] (2) The blocking components adopt a multi-layer structure arranged along the circumference of the arch, which can support the sandbags at different locations and avoid the problem of sandbag collapse. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the arch support structure for the super-large karst cave in the highway tunnel in Example 1;

[0017] Figure 2 This is a front view of the super-large karst cave arch support structure in Example 1 of the highway tunnel;

[0018] Figure 3 This is a schematic diagram of the arch support structure for the super-large karst cave in the highway tunnel in Example 2;

[0019] Figure 4 This is a schematic diagram of the arch support structure for the super-large karst cave in the highway tunnel in Example 3;

[0020] Figure 5 This is a cross-sectional view of a karst cave structure detected by lidar scanning in Example 1;

[0021] Figure 6 This is a cross-sectional view of the material texture of the cave structure in Example 1;

[0022] Figure 7 This is a photograph of the actual backfilling of the slag at the bottom of the karst cave in Example 1, showing the layered compaction process.

[0023] Figure label:

[0024] 1-Arch protection; 2-Sand; 3-Sandbag; 41-Blocking strip; 42-Woven strip; 43-Blocking block. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] Acquire raw data using a LiDAR scanner ( Figure 5 , Figure 6The karst cave is 50 meters long, 58 meters wide, and 35 meters high. The roadway is located in the middle of the cave, below the bottom of the inverted arch. The cave is 8 meters deep, and the entire cross-section of the cave is hollow. The cave extends upwards at a 70-degree angle towards the tunnel entrance, and its height is considerable, making it impossible to determine its exact size manually. A method of filling the lower part of the cave with a top buffer, and integrating other structures with the normal tunnel construction structure, was used to quickly traverse and treat the karst cave.

[0028] Layered compaction and backfilling of the karst cave bottom debris ( Figure 7 After the mud and debris at the bottom of the karst cave are cleared, the testing unit will determine the condition of the bottom. Tunnel muck will then be used to backfill to the bottom of the invert arch. On the left side of the route, backfilling will extend to the free face of the karst cavity. On the right side of the route, backfilling will be carried out along the bottom of the karst cave at a slope ratio of 1:1.5, extending 5 meters beyond the outer side of the arch support at a height of 3.1 meters. The construction sequence for backfilling the bottom of the karst cave is as follows: construction preparation → material transportation → paving → crushing of large-diameter stones → filling gaps with fine-grained materials → local leveling → vibratory compaction → testing → next cycle of construction.

[0029] like Figure 1-2 As shown, this embodiment provides a protective arch structure for a super-large karst cave in a highway tunnel, including a protective arch 1 and a buffer layer above the protective arch. Strip foundations, 50 meters long, 1.87 meters wide, and 0.5 meters high, are poured on both sides of the protective arch 1 as the foundation for the arch support frame. The protective arch 1 includes an outer arch frame and an inner arch frame, both of which are fitted with steel mesh. Shotcrete is applied to the outer and inner arch frames to form the integral structure of the protective arch 1. A road surface steel mesh is laid inside the protective arch 1 before concrete is poured to prevent settlement due to uneven filling at the bottom of the karst cave.

[0030] A buffer layer is installed on the outer arch frame. This buffer layer primarily buffers the impact of falling debris from the top of the karst cave, preventing damage to the tunnel and potential accidents. The buffer layer is divided into a retaining area and a sand-filled area. The sand-filled area is located directly above the arch support 1, with the retaining area on either side. The sand-filled area is filled with sand 2. Several blocking strips 41 are installed in the retaining area, with sandbags 3 fully laid between the blocking strips 41. The sandbags 3 are stacked alternately upwards along the circumference of the arch support 1. The blocking strips 41 support the sandbags 3, preventing them from collapsing. Simultaneously, the sandbags 3 also act as a buffer. The width of the sandbags 3 is slightly larger than the width of the blocking strips 41, meaning the sandbags 3 protrude slightly outwards radially. Falling debris from the top of the karst cave will first land on the sandbags 3, not on the blocking strips 41, effectively preventing the falling debris from the top of the karst cave from affecting the arch support 1.

[0031] Construction employed a method of full-width cross-section and layered longitudinal filling. Excavators and loaders, along with dump trucks, were used to transport the fill material. Excavators were used for paving, layered filling, and vibratory rollers for compaction. The construction sequence, work schedule, and key process cycles were carefully planned to ensure seamless and continuous operation of excavation, loading, transportation, unloading, and compaction, avoiding interference and overlapping work. Fill elevation was controlled by layering along the tunnel parallel lines, with each layer being paved in parallel. Compaction methods and loose-lay thickness were controlled according to parameters determined in the test section.

[0032] Example 2

[0033] like Figure 3 As shown, this embodiment discloses another type of arch support structure for super-large karst caves in highway tunnels. The upper part of the arch support 1 includes a sand-filling area and a retaining area. The sand-filling area is filled with sand 2, and the retaining area is provided with cross-arranged woven strips 42. The woven strips 42 cross to form several rhomboid filling areas. Each filling area is fully covered with sandbags 3. The cross-arranged woven strips 42 constrain each other, which can improve the stability of the overall structure and improve the support for the sandbags 3.

[0034] Example 3

[0035] like Figure 4 As shown in the figure, this embodiment discloses a super-large karst cave arch support structure for highway tunnels. The upper part of the arch support 1 includes a sand-filled area and a retaining area. Several layers of blocking blocks 43 are set in the retaining area. The blocking blocks 43 are arranged at intervals and staggered. Sandbags 3 are fully laid between the blocking blocks 43. In this form, the sandbags 3 are effectively supported, and the volume of the blocking components is reduced. On the one hand, it can facilitate construction and save costs. On the other hand, it can reduce the probability of falling blocks from the top of the karst cave colliding with the blocking blocks 43.

[0036] The above-described specific examples are for illustrative purposes only and are not intended to limit the scope of this invention. Those skilled in the art to which this invention pertains can make various simple deductions, modifications, or substitutions based on the concept of this invention.

Claims

1. A protective arch structure for a super-large karst cave in a highway tunnel, comprising a protective arch (1) and a buffer layer above the protective arch, characterized in that, The buffer layer includes: The enclosure is set on both sides of the arch (1), and a sand-filling area is formed between the two enclosures. The sand-filling area is filled with sand (2), and several layers of sandbags (3) are arranged along the arch surface of the arch (1) in the enclosure.

2. The arch support structure for ultra-large karst caves in highway tunnels as described in claim 1, characterized in that, The sandbags (3) in the two adjacent layers are arranged alternately.

3. The super-large karst cave arch support structure for highway tunnels as described in claim 1 or 2, characterized in that, The enclosure is equipped with a barrier to restrict the sandbags (3) and prevent them from slipping.

4. The arch support structure for ultra-large karst caves in highway tunnels as described in claim 3, characterized in that, The blocking element is a blocking strip (41), and multiple blocking strips (41) are arranged along the circumference of the arch (1), and the blocking strips (41) are arranged in a direction parallel to the axis of the arch (1). The sandbags (3) are arranged between two adjacent blocking strips (41).

5. The arch support structure for ultra-large karst caves in highway tunnels as described in claim 3, characterized in that, The blocking element is a blocking block (43), and the blocking blocks (43) are arranged at intervals along a direction parallel to the axis of the protective arch (1); The blocking block (43) has several layers, and the sandbags (3) are arranged between adjacent blocking blocks (43).

6. The arch support structure for ultra-large karst caves in highway tunnels as described in claim 3, characterized in that, The blocking element is a woven strip (42), which is arranged in a cross pattern to form several filling areas, and the sandbag (3) is placed in the filling area.

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