Tunnel supporting method suitable for tunnel underneath penetrating joint fissure dense zone reservoir

Abstract

The invention relates to a tunnel supporting method suitable for a tunnel underneath passing joint fissure dense zone reservoir. The tunnel supporting method comprises the steps of tunnel body waterproofing, advance supporting, grouting plugging supporting used in cooperation with the advance supporting and an inverted arch of secondary lining. The tunnel influence range joint fissure dense zones are bonded into a whole through the forepoling structure, the surrounding rock stability is enhanced, and the construction safety risk is reduced. Due to the fact that the tunnel downwards penetrates through the joint fissure dense zone below the reservoir, the joint fissure dense zone possibly has a water guiding channel, the fissures are plugged through the grouting plugging structure, and the tunnel gushing risk is reduced. According to different surrounding rock grades, an advance support structure and a grouting plugging structure are ingeniously combined, the construction method under two unfavorable working conditions of tunnel underneath pass is achieved, the construction progress is accelerated, and the construction cost is reduced.

Description

Technical Field

[0001] The invention relates to a tunnel support method suitable for a tunnel passing through a reservoir with dense joints and fissures, and relates to the technical field of tunnel construction. Background Art

[0002] With the vigorous development of highway construction, the working conditions of highway tunnels crossing mountains are becoming more and more complicated. The interweaving of multiple complex working conditions has brought huge challenges to tunnel support design. Highway tunnels pass through water-rich geology and pass under reservoirs. There is a dense zone of joints and fissures under the reservoir. The tunnel surrounding rock is prone to instability and large water inflow, resulting in slow tunnel excavation speed, easy collapse and large deformation. At present, the support structure and excavation method for tunnels crossing the above working conditions at the same time have the problem of initial support deformation under the comprehensive conditions of multiple working conditions and water leakage is difficult to effectively prevent and control. Summary of the invention

[0003] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a tunnel support method suitable for a tunnel passing through a reservoir with dense joints and fissures.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a tunnel support method suitable for a tunnel passing through a reservoir with dense joints and fissures, comprising the following steps: S1: Advance support structure construction: When the tunnel excavation enters the influence area of ​​the reservoir, advance support construction is required. Within the influence area of ​​the reservoir and where there is a zone with dense joints and fissures, cement mortar anchor rods are used for advance support for Grade IV surrounding rock, and seamless steel pipes are used for advance support for Grade V surrounding rock. Directly below the reservoir and where there is a zone with dense joints and fissures, grouting seamless steel pipes are used for advance support regardless of whether it is Grade IV or Grade V surrounding rock. S2: Grouting and plugging structure construction: There is a joint and fissure intensive zone directly below the reservoir and within the influence range of the reservoir. According to the advanced horizontal drilling, if the water inflow is greater than the predetermined value or the water pressure is greater than the predetermined value, grouting and plugging are required. Regardless of the surrounding rock of grade IV or grade V, grouting and plugging construction is carried out in the specified range outside the excavation outline using grouting walls and grouting holes; S3: Tunnel excavation construction: During excavation construction, the middle partition wall method is used for Class V surrounding rock, and the step method is used for Class IV surrounding rock to reserve core soil. The predetermined length is excavated and the part used as the grouting rock wall is reserved. The tunnel excavation is mainly carried out by mechanical excavation and supplemented by weak blasting. S4: Tunnel waterproofing and secondary lining invert construction: After the tunnel excavation is completed, the initial support is carried out in time. After the initial support is completed, the tunnel waterproofing quick-setting rubber asphalt waterproof coating is constructed. After the tunnel waterproofing construction is completed, the secondary lining invert construction is carried out.

[0005] Preferably, in step S4, the tunnel waterproof coating adopts 1.5 mm quick-setting rubber asphalt waterproof coating.

[0006] Preferably, in step S1, the IV-level surrounding rock is advanced supported by cement mortar anchor rods with a diameter of 22 mm.

[0007] Preferably, in step S1, the V-level surrounding rock is advanced supported by a seamless steel pipe with an outer diameter of 50 mm and a wall thickness of 5 mm.

[0008] Preferably, in step S2, the diameter of the first 5m of several grouting holes for grouting plugging is 110mm, the diameter from 5m to the final hole is 91mm, and a hot-rolled seamless steel pipe with a diameter of 108mm is arranged in the first 5m.

[0009] Preferably, in step S2, the grouting and plugging slurry stop wall uses C25 cast-in-place concrete with a thickness of 200 cm, and the slurry stop wall is embedded in the rock mass by 0.5 m.

[0010] Preferably, in step S4, the invert arch of the secondary lining is made of C35 reinforced concrete, and the steel bars are hot-rolled ribbed steel bars with a diameter of 25 mm.

[0011] Preferably, in step S1, in the area directly below the reservoir where there is a zone with dense joints and fissures, regardless of whether the surrounding rock is level IV or level V, a grouting seamless steel pipe with an outer diameter of 50 mm and a wall thickness of 5 mm is used for advance support.

[0012] Preferably, in step S2, if the water inflow is greater than 20m 3 / h or water pressure is greater than 0.3MPa, grouting is required. Regardless of grade IV or grade V surrounding rock, grouting is carried out within six meters outside the excavation outline using stop walls and grouting holes. The length of each grouting cycle is 30m.

[0013] Preferably, in step S3, the IV-level surrounding rock is constructed by a step method of reserving core soil, with an excavation length of 20m and a 10m grouting rock wall retained.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Through the advanced support structure, the dense joint and fissure zones in the tunnel influence range are bonded into a whole, thereby enhancing the stability of the surrounding rock and reducing construction safety risks.

[0015] 2. As the tunnel passes under the reservoir, there may be water channels in the zone with dense joints and fissures. The fissures can be sealed with a grouting plugging structure to reduce the risk of sudden surges in the tunnel.

[0016] 3. According to different surrounding rock grades, the advanced support structure and the grouting plugging structure are cleverly combined to solve the construction methods under two unfavorable conditions of tunnel underpass, speed up the construction progress and reduce the construction cost.

[0017] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a cross-sectional view of a grouting seamless steel pipe advance support tunnel according to an embodiment of the present invention.

[0019] Figure 2 for Figure 1 AA cross-section diagram.

[0020] Figure 3 This is a cross-sectional view of a cement mortar anchor advance support tunnel according to an embodiment of the present invention.

[0021] Figure 4 for Figure 3 BB cross-section diagram.

[0022] Figure 5 This is a cross-sectional view of a grouting-sealed tunnel according to an embodiment of the present invention.

[0023] Figure 6 This is a plan view of a grouting-plugged tunnel according to an embodiment of the present invention.

[0024] Figure 7 This is a cross-sectional view of a tunnel waterproof coating according to an embodiment of the present invention.

[0025] Figure 8 This is a cross-sectional view of a tunnel reinforced concrete invert and steel bar arrangement according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0029] like Figures 1 to 8 As shown, this embodiment provides a tunnel support method suitable for a tunnel passing through a reservoir with dense joints and fissures, comprising the following steps: S1: Advance support structure construction: When the tunnel excavation enters the influence area of ​​the reservoir, advance support construction is required. Within the influence area of ​​the reservoir and where there is a zone with dense joints and fissures, cement mortar anchor rods are used for advance support for Grade IV surrounding rock, and seamless steel pipes are used for advance support for Grade V surrounding rock. Directly below the reservoir and where there is a zone with dense joints and fissures, grouting seamless steel pipes are used for advance support regardless of whether it is Grade IV or Grade V surrounding rock. S2: Grouting and plugging structure construction: There is a joint and fissure intensive zone directly below the reservoir and within the influence range of the reservoir. According to the advanced horizontal drilling, if the water inflow is greater than the predetermined value or the water pressure is greater than the predetermined value, grouting and plugging are required. Regardless of the surrounding rock of grade IV or grade V, grouting and plugging construction is carried out in the specified range outside the excavation outline using grouting walls and grouting holes; S3: Tunnel excavation construction: During excavation construction, the middle partition wall method is used for Class V surrounding rock, and the step method is used for Class IV surrounding rock to reserve core soil. The predetermined length is excavated and the part used as the grouting rock wall is reserved. The tunnel excavation is mainly carried out by mechanical excavation and supplemented by weak blasting. S4: Tunnel waterproofing and secondary lining invert construction: After the tunnel excavation is completed, the initial support is carried out in time. After the initial support is completed, the tunnel waterproofing quick-setting rubber asphalt waterproof coating is constructed. After the tunnel waterproofing construction is completed, the secondary lining invert construction is carried out.

[0030] In an embodiment of the present invention, in step S4, the tunnel waterproof coating adopts 1.5 mm quick-setting rubber asphalt waterproof coating.

[0031] In the embodiment of the present invention, in step S1, the IV-level surrounding rock is advanced supported by cement mortar anchor rods with a diameter of 22 mm.

[0032] In the embodiment of the present invention, in step S1, the V-level surrounding rock is advanced supported by a seamless steel pipe with an outer diameter of 50 mm and a wall thickness of 5 mm.

[0033] In the embodiment of the present invention, in step S2, the diameter of the first 5m of several grouting holes for grouting plugging is 110mm, the diameter from 5m to the final hole is 91mm, and a hot-rolled seamless steel pipe with a diameter of 108mm is arranged in the first 5m.

[0034] In the embodiment of the present invention, in step S2, the grouting and plugging grouting stop wall uses C25 cast-in-place concrete with a thickness of 200 cm, and the grouting stop wall is embedded in the rock mass by 0.5 m.

[0035] In the embodiment of the present invention, in step S4, the invert arch of the secondary lining is made of C35 reinforced concrete, and the steel bars are hot-rolled ribbed steel bars with a diameter of 25 mm.

[0036] In the embodiment of the present invention, in step S1, in the area directly below the reservoir where there is a dense zone of joints and fissures, whether it is grade IV or grade V surrounding rock, a 50mm outer diameter and 5mm wall thickness grouting seamless steel pipe is used for advance support.

[0037] In the embodiment of the present invention, in step S2, if the water inflow is greater than 20m 3 / h or water pressure is greater than 0.3MPa, grouting is required. Regardless of grade IV or grade V surrounding rock, grouting is carried out within six meters outside the excavation outline using stop walls and grouting holes. The length of each grouting cycle is 30m.

[0038] In the embodiment of the present invention, in step S3, the IV-level surrounding rock adopts the step method to reserve the core soil, the excavation length is 20m, and a 10m grouting rock wall is retained.

[0039] The supporting structures suitable for tunnels passing through reservoirs with dense joints and fissures include tunnel body waterproofing, advance support, grouting sealing support used in conjunction with advance support, and secondary lining inverts.

[0040] Tunnel body waterproofing includes several waterproof coatings set along the length of the tunnel. Advanced support includes several cement mortar anchors or several grouting seamless steel pipes set at a certain angle and length beyond the face along the length of the tunnel. Grouting plugging support includes several grouting holes and grouting walls set at a certain angle and length beyond the face along the length of the tunnel. The invert of the secondary lining includes a reinforced concrete structure of a certain thickness set at the bottom of the tunnel along the length of the tunnel.

[0041] Specific implementation process: S1: Construction of advance support structure: When entering the influence area of ​​the reservoir, the tunnel advance support structure is constructed first. In the IV and V grade surrounding rocks directly below the reservoir with dense joints and fissures, advance support is carried out using 50mm outer diameter, 5mm wall thickness grouting seamless steel pipe 1.1. The seamless steel pipe 1.1 is 5m long, with a circumferential spacing of 40cm and a longitudinal spacing of 3.5m. The external insertion angle is 12°. The grouting is cement slurry with a water-cement ratio of 0.5:1 and a grouting pressure of 0.5-1MPa. The IV-level surrounding rock with dense joints and fissures within the influence range of the reservoir is supported in advance by cement mortar anchor rods 1.2 with a diameter of 22 mm. The length of cement mortar anchor rods 1.2 is 3.5 m, the circumferential spacing of cement mortar anchor rods 1.2 is 40 cm, the longitudinal spacing is 2.1 m, and the external insertion angle is 15°. The V-level surrounding rock with dense joints and fissures within the influence range of the reservoir is the same as the advanced support structure with dense joints and fissures directly below the reservoir.

[0042] S2: Grouting and plugging structure construction: For the IV and V grade surrounding rocks with dense joints and fissures directly below the reservoir and within the influence range of the reservoir, grouting and plugging construction shall be carried out after the advanced support construction is completed. The grouting and plugging construction shall first construct the grouting wall 2.1. Before the construction of the grouting wall 2.1, the steel mesh shall be hung and the face 2.2 shall be sealed by concrete spraying. The closed face 2.2 shall be repaired and cleaned of loose soil. After the face 2.2 is stable, the C25 formwork concrete formwork shall be used on the upper step to cast 200cm thick concrete as the grouting wall 2.1. The grouting wall 2.1 shall be embedded 0.5m into the rock mass. When constructing the grouting hole 2.3, a φ110mm drill bit shall be used for drilling in the first 5m, and a φ91mm drill bit shall be used for drilling in the last 5m to the final hole position. The orifice pipe shall be a hot-rolled seamless steel pipe with a diameter of 108mm, a wall thickness of 6mm, and a pipe length of 5m. The starting point of the first cycle of grouting should be about 5~10m away from the predicted water inrush section, and the end point of grouting should be about 5~10m beyond the predicted water inrush section. The grouting plugging range is 6m beyond the tunnel excavation line. The grouting holes are arranged in an umbrella shape from the face along the excavation direction with the tunnel axis as the center. The effective diffusion radius of the slurry is not less than 2m, and the spacing between the end holes is not more than 3m. Seven rings of grouting holes are set in each cycle. The grouting material is ordinary cement-water glass double liquid slurry. SJP grouting material is added when necessary. The ratio of SJP grouting material is 2%~3% of the cement mass, the water-cement ratio of cement slurry is 0.5:1, and the volume ratio of cement slurry to water glass is 1:1~1:0.5.

[0043] S3: Tunnel excavation construction: After the advanced support and grouting plugging construction are completed, the tunnel is excavated. During excavation, since the grouting length of each cycle of grouting plugging is 30m, the excavation length is 20m, and 10m is reserved as the grouting rock wall 2.4, and then the second cycle of grouting plugging structure construction is carried out. During excavation construction, the middle partition wall method is used for the V-level surrounding rock, and the step method is used for the IV-level surrounding rock to reserve the core soil. The tunnel excavation is mainly carried out by mechanical excavation, supplemented by weak blasting.

[0044] S4: Tunnel waterproofing and secondary lining invert construction: After the tunnel excavation is completed, the initial support 4.3 is carried out in time. After the initial support 4.3 is completed, a layer of 1.5mm waterproof quick-setting rubber asphalt waterproof coating 4.4 is set immediately. The waterproof coating 4.4 is constructed before the tunnel waterproof board 4.5 as an additional waterproof measure for the tunnel under the reservoir tunnel with dense joints and fissures. After the tunnel waterproofing construction is completed, the reinforced concrete invert 4.6 of the secondary lining is constructed. For the IV-level surrounding rock, the thickness of the reinforced concrete invert 4.6 is set to 50cm, and the steel bars are hot-rolled ribbed steel bars with a diameter of 25mm, with a longitudinal spacing of 10cm and a circumferential spacing of 10cm. For the V-level surrounding rock, the thickness of the reinforced concrete invert 4.6 is set to 55cm, and the steel bars are hot-rolled ribbed steel bars with a diameter of 25mm, with a longitudinal spacing of 10cm and a circumferential spacing of 10cm.

[0045] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A tunnel support method suitable for a tunnel passing through a reservoir with dense joints and fissures, characterized in that: The following steps are involved: S1: Advance support structure construction: When the tunnel excavation enters the influence area of ​​the reservoir, advance support construction is required. Within the influence area of ​​the reservoir and where there is a zone with dense joints and fissures, cement mortar anchor rods are used for advance support for Grade IV surrounding rock, and seamless steel pipes are used for advance support for Grade V surrounding rock. Directly below the reservoir and where there is a zone with dense joints and fissures, grouting seamless steel pipes are used for advance support regardless of whether it is Grade IV or Grade V surrounding rock. S2: Grouting and plugging structure construction: There is a joint and fissure intensive zone directly below the reservoir and within the influence range of the reservoir. According to the advanced horizontal drilling, if the water inflow is greater than the predetermined value or the water pressure is greater than the predetermined value, grouting and plugging are required. Regardless of the surrounding rock of grade IV or grade V, grouting and plugging construction is carried out in the specified range outside the excavation outline using grouting walls and grouting holes; S3: Tunnel excavation construction: During excavation construction, the middle partition wall method is used for Class V surrounding rock, and the step method is used for Class IV surrounding rock to reserve core soil. The predetermined length is excavated and the part used as the grouting rock wall is reserved. The tunnel excavation is mainly carried out by mechanical excavation and supplemented by weak blasting. S4: Tunnel waterproofing and secondary lining invert construction: After the tunnel excavation is completed, the initial support is carried out in time. After the initial support is completed, the tunnel waterproofing quick-setting rubber asphalt waterproof coating is constructed. After the tunnel waterproofing construction is completed, the secondary lining invert construction is carried out.

2. The tunnel support method according to claim 1, which is suitable for a tunnel passing through a reservoir with dense joints and fissures, is characterized in that: In step S4, the tunnel waterproof coating adopts 1.5 mm quick-setting rubber asphalt waterproof coating.

3. The tunnel support method according to claim 1, which is suitable for a tunnel passing through a reservoir with dense joints and fissures, is characterized in that: In step S1, the IV-level surrounding rock is advanced supported by cement mortar anchors with a diameter of 22 mm.

4. The tunnel support method according to claim 1, which is suitable for a tunnel passing through a reservoir with dense joints and fissures, is characterized in that: In step S1, the V-level surrounding rock is supported in advance by seamless steel pipes with an outer diameter of 50 mm and a wall thickness of 5 mm.

5. The tunnel support method according to claim 1, which is suitable for a tunnel passing through a reservoir with dense joints and fissures, is characterized in that: In step S2, the diameter of the first 5m of several grouting holes for grouting plugging is 110mm, the diameter of the hole from 5m to the final hole is 91mm, and a hot-rolled seamless steel pipe with a diameter of 108mm is set in the first 5m.

6. The tunnel support method according to claim 1, which is suitable for a tunnel passing through a reservoir with dense joints and fissures, is characterized in that: In step S2, the grouting and plugging grouting wall uses C25 cast-in-place concrete with a thickness of 200 cm, and the grouting wall is embedded in the rock mass by 0.5 m.

7. The tunnel support method according to claim 1, which is suitable for a tunnel passing through a reservoir with dense joints and fissures, is characterized in that: In step S4, the invert arch of the secondary lining is made of C35 reinforced concrete, and the steel bars are hot-rolled ribbed steel bars with a diameter of 25 mm.

8. The tunnel support method according to claim 1, which is suitable for a tunnel passing through a reservoir with dense joints and fissures, is characterized in that: In step S1, in the area directly below the reservoir where there is a dense zone of joints and fissures, regardless of whether the surrounding rock is level IV or level V, grouting seamless steel pipes with an outer diameter of 50 mm and a wall thickness of 5 mm are used for advance support.

9. The tunnel support method applicable to a tunnel passing under a reservoir with dense joints and fissures according to claim 1, characterized in that: In step S2, if the water inflow is greater than 20m 3 / h or water pressure is greater than 0.3MPa, grouting is required. Regardless of grade IV or grade V surrounding rock, grouting is carried out within six meters outside the excavation outline using stop walls and grouting holes. The length of each grouting cycle is 30m.

10. The tunnel support method applicable to a tunnel passing under a reservoir with dense joints and fissures according to claim 1, characterized in that: In step S3, the construction method of reserving core soil for the IV-level surrounding rock is adopted, the excavation length is 20m, and a 10m grouting rock wall is retained.

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