Construction method for cover-excavation structure of ultra-shallow-buried semi-open and semi-dark tunnel

Abstract

The invention relates to a construction method of an ultra-shallow-buried semi-open and semi-dark tunnel cover-excavation structure. The construction method of the cover-excavation structure of the ultra-shallow-buried semi-open and semi-dark tunnel specifically comprises the following steps that an original landform is excavated, a vault upper layer is excavated, and excavation faces on the two sides of the vault upper layer are subjected to soil body supporting; a vault protection arch is constructed at the bottom of the vault upper layer, and the bottom and the two sides of the vault protection arch are reinforced; excavation supporting structure construction is conducted from top to bottom in a step layering mode below the arch crown protection arch; an inverted arch lining, inverted arch filling and an arch wall lining are sequentially constructed in the excavation supporting structure; and vault backfill layer construction is conducted on the vault upper layer, wherein a vault backfill layer comprises a water seepage prevention stable layer arranged on the vault upper layer and a ground surface water-resisting layer arranged on the water seepage prevention stable layer. The construction method of the cover and excavation structure of the ultra-shallow-buried semi-open and semi-dark tunnel has the advantages of being high in deformation resistance and small in water leakage risk.

Description

Technical Field

[0001] The present invention relates to the field of tunnel construction, in particular to a construction method for an ultra-shallow buried semi-open and semi-hidden tunnel cover-excavation structure. Background Art

[0002] With rapid economic development and the continuous advancement of road construction, the demand for underground tunnels, such as subways and underground roads, is increasing. However, when constructing tunnels beneath extremely shallow strata, the tunnel's advanced support structures and reinforced support structures must withstand the effects of surface water seepage and the collapse of unstable surface soil and rock layers. Due to the highly weathered and soft soil at the tunnel top, there is a risk of collapse. Furthermore, surface water can easily seep into the tunnel structure, posing a high safety risk during construction and a significant risk of structural deformation and water leakage during later operation. Summary of the Invention

[0003] Based on this, the purpose of the present invention is to provide a construction method for an ultra-shallow buried semi-open and semi-hidden tunnel cover-excavation structure, which has the advantages of strong anti-deformation ability and low risk of water leakage.

[0004] A construction method for an ultra-shallow buried semi-exposed and semi-hidden tunnel cover-excavation structure specifically comprises the following steps:

[0005] S1 excavates the original landform to excavate the upper layer of the vault, provides soil support for the excavation surfaces on both sides of the upper layer of the vault, and controls overexcavation;

[0006] S2 constructs a vault guard at the bottom of the upper vault layer and reinforces the bottom and both sides of the vault guard;

[0007] S3: constructing an excavation support structure below the arch crown from top to bottom in a stepped and layered manner, wherein the excavation support structure is divided into at least three layers;

[0008] S4: constructing the inverted arch lining, the inverted arch filling and the arch wall lining in sequence within the excavation support structure;

[0009] S5 constructs a vault backfill layer on the vault upper layer, wherein the vault backfill layer includes an anti-seepage water-stabilizing layer provided on the vault upper layer and a surface aquiclude provided on the anti-seepage water-stabilizing layer.

[0010] Compared with the existing technology, the ultra-shallow buried semi-open and semi-concealed tunnel cover and excavation structure construction method described in the present invention improves the deformation resistance by constructing the excavation support structure in a step-by-step layered manner, and constructs the arch backfill layer in the upper layer of the arch, and sets an anti-seepage water-stabilizing layer and a surface water-isolating layer to improve the waterproofness of the tunnel.

[0011] Furthermore, the step S5 specifically includes the following steps:

[0012] S51: backfilling the anti-seepage and water-stabilizing layer from both sides of the upper layer of the arch to the middle above the arch;

[0013] S52 performs backfill construction of the surface aquiclude on the anti-seepage water-stabilizing layer.

[0014] Furthermore, in the step S51, during construction, the anti-seepage water-stabilizing layer is constructed from both sides toward the middle in a layered and symmetrical manner; when the anti-seepage water-stabilizing layer is constructed in layers, the thickness of each layer is not greater than 0.5 m.

[0015] Furthermore, the surface waterproof layer is paved with thick mortared flagstones, and the thickness of the thick mortared flagstones is 0.3m.

[0016] Furthermore, the lower side of the upper layer of the arch is the arch protection soil, and both sides of the upper layer of the arch are excavation surfaces, and the slopes of the excavation surfaces on both sides are less than 1:0.75.

[0017] Furthermore, the step S2 specifically includes the following steps:

[0018] S21 trims the surface of the arch protection soil to the curvature of the target arch crown;

[0019] S22 constructs an arch crown protection on the arch protection soil;

[0020] S23: large arch feet are provided at the bottom of both sides of the arch guard, and steel pipe locking feet are provided at intervals along the bottom of both sides of the arch guard.

[0021] Furthermore, the thickness of the arch guard is not less than 0.8m; the width of the large arch foot 2a is not less than 1.5m; the length of the steel pipe locking foot is not less than 5m, and the spacing between the steel pipe locking feet on the same side of the bottom of the arch guard is between 0.4 and 0.6m.

[0022] Furthermore, the step S3 specifically includes the following steps:

[0023] S31 constructs an upper excavation support structure below the arch crown guard;

[0024] S32 constructing a middle excavation support structure below the upper excavation support structure, wherein the middle excavation support structure is 4 to 6 meters away from the tunnel face compared to the upper excavation support structure;

[0025] S33 constructs a lower excavation support structure below the middle excavation support structure. The lower excavation support structure 33 is 4 to 6 meters away from the tunnel face compared with the middle excavation support structure 32.

[0026] Furthermore, the excavation support structures of each layer are divided into symmetrical left support structures and right support structures with the central axis of the overall cover excavation structure as the symmetry axis, and the left support structure and the right support structure are staggered 3 to 5 meters front and back.

[0027] Furthermore, the step S4 specifically includes the following steps:

[0028] S41: constructing an inverted arch lining and an inverted arch filling in sequence; the inverted arch lining is arranged on the lower excavation support structure, and the inverted arch filling is arranged on the inverted arch lining; the distance between the inverted arch lining and the inverted arch filling and the tunnel face is not more than 30m;

[0029] S42 constructs an arch wall lining inside the upper excavation support structure and the middle excavation support structure, and the distance between the arch wall lining and the tunnel face is not more than 45m.

[0030] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a construction diagram of step S1 of an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the construction of step S2 of an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the construction of step S3 of an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the construction of step S4 in an embodiment of the present invention;

[0035] Figure 5 This is a construction diagram of step S5 in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the terms "vertical," "upper," "lower," and "horizontal," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to thermally conductive connections, detachable connections, or integral connections. They may also refer to mechanical connections or electrical connections. They may also refer to direct connections or connections through an intermediate medium. They may also refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] Example

[0040] See also Figure 1-Figure 2 The present invention discloses a construction method for an ultra-shallow buried semi-open and semi-hidden tunnel cover-excavation structure.

[0041] The construction method of the ultra-shallow buried semi-open and semi-hidden tunnel cover-excavation structure of the present invention specifically comprises the following steps:

[0042] S1: Excavate the original landform to excavate the upper layer 1 of the vault, provide soil support for the excavation surface 1b on both sides of the upper layer 1 of the vault, and control over-excavation;

[0043] S2: construct the arch guard 2 at the bottom of the upper arch layer 1, and reinforce the bottom and both sides of the arch guard 2;

[0044] S3: Excavate and construct the support structure 3 in layers from top to bottom under the arch guard 2. The excavation support structure 3 is divided into at least three layers.

[0045] S4: constructing the inverted arch lining 41, the inverted arch filling 42 and the arch wall lining 43 in sequence within the excavation support structure 3;

[0046] S5: constructing the vault backfill layer 5 on the vault upper layer 1 , the vault backfill layer 5 includes an anti-seepage water-stabilizing layer 51 provided on the vault upper layer 1 and a surface aquiclude 52 provided on the anti-seepage water-stabilizing layer 51 .

[0047] Furthermore, in step S1 , the lower side of the vault upper layer 1 is the arch protection soil 1 a , and both sides of the vault upper layer 1 are the excavation surfaces 1 b , and the slopes of the excavation surfaces 1 b on both sides are less than 1:0.75.

[0048] Controlling the slope of the excavation surface 1b can prevent soil and rock collapse and improve construction stability.

[0049] Furthermore, step S2 specifically includes:

[0050] S21: trimming the surface of the arch protection soil 1a at the bottom of the upper layer 1 of the arch to the curvature of the target arch protection 2;

[0051] S22: constructing the arch crown protection 2 on the arch protection soil 1a;

[0052] S23: Large arch feet 2a are provided at the bottom of both sides of the arch crown guard 2, and steel pipe locking feet 2b are provided at intervals along the bottom of both sides of the arch crown guard 2.

[0053] Furthermore, in step S22, the thickness of the arch guard 2 is no less than 0.8 m. In step S23, the width of the large arch foot 2a is no less than 1.5 m. One end of the steel pipe locking foot 2b is driven obliquely into the bottom of the arch guard 2. The length of the steel pipe locking foot 2b is no less than 5 m. The spacing between the steel pipe locking feet 2b on the same side of the bottom of the arch guard 2 is between 0.4 and 0.6 m, preferably 0.5 m. In some embodiments, the steel pipe of the steel pipe locking foot 2b is Φ89 steel flower pipe.

[0054] The large arch foot 2a provides an expanded rigid support base for the arch guard 2, improving structural stability, preventing the arch guard 2 from sinking, and reducing the impact of collapse from unstable surface soil and rock layers. The steel pipe locking foot 2b is used to secure the arch guard 2, preventing it from moving and preventing the entire support structure from slipping.

[0055] Furthermore, step S3 specifically includes the following steps:

[0056] S31: construct upper excavation support structure 31 below the arch crown 2;

[0057] S32: constructing a middle excavation support structure 32 below the upper excavation support structure 31. The middle excavation support structure 32 is 4 to 6 meters away from the tunnel face compared to the upper excavation support structure 31.

[0058] S33: construct a lower excavation support structure 33 below the middle excavation support structure 32. The lower excavation support structure 33 is 4 to 6 meters away from the tunnel face compared to the middle excavation support structure 32.

[0059] Furthermore, in steps S31, S32 and S33, each layer of excavation support structure 3 is divided into a symmetrical left support structure and a right support structure with the central axis of the overall cover excavation structure as the axis of symmetry, and the left support structure and the right support structure are staggered by 3 to 5 meters front and back (that is, the distance between the left support structure and the right support structure and the tunnel face differs by 3 to 5 meters).

[0060] The excavation support structure 3 of the embodiment of the present invention is constructed in a stepped and layered manner and staggered left and right. The formed stepped structure can provide more stable support and improve the stability of the overall structure.

[0061] Furthermore, step S4 specifically includes the following steps:

[0062] S41: construct the inverted arch lining 41 and the inverted arch filling 42 in sequence; the inverted arch lining 41 is set on the lower excavation support structure 33, and the inverted arch filling 42 is set on the inverted arch lining 41; the distance between the inverted arch lining 41 and the inverted arch filling 42 and the tunnel face is not more than 30m;

[0063] S42: Construct an arch wall lining 43 inside the upper excavation support structure 31 and the middle excavation support structure 32. The distance between the arch wall lining 43 and the tunnel face is not more than 45m.

[0064] Furthermore, step S5 specifically includes the following steps:

[0065] S51: Above the arch guard 2, backfill the anti-seepage water-stabilizing layer 51 from both sides of the arch upper layer 1 to the middle;

[0066] S52: Backfilling construction of the surface aquiclude 52 is performed on the anti-seepage water-stabilizing layer 51.

[0067] Furthermore, in step S51, the anti-seepage water-stabilizing layer 51 is constructed in a symmetrical layered manner from both sides toward the center to ensure uniformity of the anti-seepage water-stabilizing layer 51 and avoid voids. In some embodiments, the anti-seepage water-stabilizing layer 51 is constructed in layers, with each layer being no thicker than 0.5 m.

[0068] In some embodiments, the backfill of the anti-seepage water-stabilizing layer 51 is constructed manually with the help of small machines; the anti-seepage water-stabilizing layer 51 is a 10% cement-soil mixture.

[0069] Furthermore, in step S52, the surface waterproof layer 52 is backfilled by paving thick mortar slabs. In some embodiments, the thickness of the thick mortar slabs is 0.3 m.

[0070] In the method for constructing an ultra-shallow semi-obscure tunnel cover-and-tunnel structure according to the embodiment of the present invention, the surface aquiclude 52 acts as a water-proof barrier, preventing water from eroding and consuming the underlying anti-seepage water-stabilizing layer 51. The anti-seepage water-stabilizing layer 51 can prevent surface water from seeping into the tunnel structure, reducing the risk of tunnel leakage. The excavation support structure 3 is constructed by stepping and layering, thereby improving its support capacity. The method for constructing an ultra-shallow semi-obscure tunnel cover-and-tunnel structure according to the embodiment of the present invention has high deformation resistance and water-seepage resistance.

[0071] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to encompass such modifications and variations.

Claims

1. A construction method for an ultra-shallow semi-blind tunnel cover-excavation structure, characterized in that: The specific steps include: S1 excavates the original landform to excavate the upper layer of the vault, provides soil support for the excavation surfaces on both sides of the upper layer of the vault, and controls over-excavation; S2 constructs a vault guard at the bottom of the upper vault layer and reinforces the bottom and both sides of the vault guard; S3: constructing an excavation support structure below the arch crown from top to bottom in a stepped and layered manner, wherein the excavation support structure is divided into at least three layers; S4: constructing the inverted arch lining, the inverted arch filling and the arch wall lining in sequence within the excavation support structure; S5 constructs a vault backfill layer on the vault upper layer, wherein the vault backfill layer includes an anti-seepage water-stabilizing layer provided on the vault upper layer and a surface aquiclude provided on the anti-seepage water-stabilizing layer.

2. The construction method of the ultra-shallow buried semi-open and semi-hidden tunnel cover-excavation structure according to claim 1 is characterized in that: The step S5 specifically includes the following steps: S51: backfilling the anti-seepage and water-stabilizing layer from both sides of the upper layer of the arch to the middle above the arch; S52 performs backfill construction of the surface aquiclude on the anti-seepage water-stabilizing layer.

3. The method for constructing an ultra-shallow semi-obscure tunnel cover-excavation structure according to claim 2 is characterized in that: In step S51, during construction, the anti-seepage water-stabilizing layer is constructed from both sides toward the middle in a layered and symmetrical manner; when the anti-seepage water-stabilizing layer is constructed in layers, the thickness of each layer is not greater than 0.5 m.

4. The construction method of the ultra-shallow semi-open and semi-hidden tunnel cover-excavation structure according to claim 3 is characterized by: The surface waterproof layer is paved with thick mortar slabs, and the thickness of the thick mortar slabs is 0.3m.

5. The method for constructing an ultra-shallow semi-obscure tunnel cover-excavation structure according to any one of claims 1 to 4, characterized in that: The lower side of the upper layer of the arch is the arch protection soil, and both sides of the upper layer of the arch are excavation surfaces, and the slopes of the excavation surfaces on both sides are less than 1:0.

75.

6. The construction method of the ultra-shallow buried semi-open and semi-hidden tunnel cover-excavation structure according to claim 5 is characterized in that: The step S2 specifically includes the following steps: S21 trims the surface of the arch protection soil to the curvature of the target arch crown; S22 constructs an arch crown protection on the arch protection soil; S23: large arch feet are provided at the bottom of both sides of the arch guard, and steel pipe locking feet are provided at intervals along the bottom of both sides of the arch guard.

7. The method for constructing an ultra-shallow semi-exposed and semi-hidden tunnel cover-excavation structure according to claim 6 is characterized in that: The thickness of the arch guard arch is not less than 0.8m; the width of the large arch foot 2a is not less than 1.5m; the length of the steel pipe locking foot is not less than 5m, and the spacing between the steel pipe locking feet on the same side of the bottom of the arch guard arch is between 0.4 and 0.6m.

8. The construction method of the ultra-shallow semi-open and semi-hidden tunnel cover-excavation structure according to claim 6 is characterized in that: The step S3 specifically includes the following steps: S31 constructs an upper excavation support structure below the arch crown guard; S32 constructing a middle excavation support structure below the upper excavation support structure, wherein the middle excavation support structure is 4 to 6 meters away from the tunnel face compared to the upper excavation support structure; S33 constructs a lower excavation support structure below the middle excavation support structure. The lower excavation support structure 33 is 4 to 6 meters away from the tunnel face compared with the middle excavation support structure 32.

9. The method for constructing an ultra-shallow semi-exposed and semi-blind tunnel cover-excavation structure according to claim 8, characterized in that: The excavation support structures of each layer are symmetrically divided into a left support structure and a right support structure with the central axis of the overall cover excavation structure as the axis of symmetry, and the left support structure and the right support structure are staggered 3 to 5 meters front and back.

10. The construction method of the ultra-shallow buried semi-open and semi-hidden tunnel cover-excavation structure according to claim 8 is characterized in that: The step S4 specifically includes the following steps: S41: constructing an inverted arch lining and an inverted arch filling in sequence; the inverted arch lining is arranged on the lower excavation support structure, and the inverted arch filling is arranged on the inverted arch lining; the distance between the inverted arch lining and the inverted arch filling and the tunnel face is not more than 30m; S42 constructs an arch wall lining inside the upper excavation support structure and the middle excavation support structure, and the distance between the arch wall lining and the tunnel face is not more than 45m.

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