Deformation treatment method for steep-dip phyllite

Abstract

The invention relates to a deformation treatment method for steep-dip phyllite, and relates to the field of civil engineering. The deformation treatment method comprises the steps that a tunnel body is excavated, the reserved deformation amount between a primary support and a secondary lining is designed, the tunnel body comprises a vault and a side wall, the deformation amount of the reserved vault is S1, the deformation amount of the reserved side wall is S2, and S1 is smaller than S2; and primary supporting and secondary lining are carried out in the tunnel body. According to the deformation treatment method for the steep-dip phyllite, under comprehensive analysis of geological survey and monitoring measurement, the heterogeneous deformation mechanism of surrounding rock after excavation is determined, it is proposed that the arch crown and the side wall adopt different reserved deformation amounts, and the deformation convergence rule of the surrounding rock on site is met; and therefore, instability and collapse of the right wall due to the gravity effect under the condition of blasting disturbance are avoided.

Description

Technical Field

[0001] The invention relates to the field of civil engineering, and in particular to a deformation treatment method for steeply inclined phyllite. Background Art

[0002] In recent years, more and more mountain roads have been planned and built. More and more tunnels have also been planned and built, especially in some southwestern mountainous areas. Tunnels with high seismic intensity, accompanied by fault fracture zones, and water-rich phyllite strata have brought great difficulties to tunnel construction. The initial support has long-term deformation, large deformation, and large deformation is a post-event problem, which has brought great hidden dangers to tunnel construction safety and structural safety. Up to now, the existing technologies have different opinions on the treatment of large deformation. Ensuring construction safety and structural safety is a pain point, key point and difficulty in the current tunnel construction field, and has always been a field of continuous exploration for disaster reduction and prevention of mountain roads. Phyllite is soft in nature, easy to muddy and soften when exposed to water, has expansion and contraction, and has poor engineering geological properties, which will lead to large deformation. It has poor weathering resistance and is easy to weather to form rock debris and produce fragmentation. The complex geological conditions of mountain highways or railway tunnels have brought great difficulties to tunnel construction, especially the high-intensity water-rich phyllite accompanied by fault fracture zones. Its large deformation has brought great hidden dangers to construction safety and structural safety. How to effectively treat it has become a difficult problem in the engineering community.

[0003] The inventors have found that the current arch is relatively stable after excavation, the left wall is under-excavated frequently, and the right wall is over-excavated frequently. This is mainly because the surrounding rock loses support after the excavation of the right wall, and is prone to instability and collapse under the influence of blasting disturbance and gravity. Summary of the invention

[0004] The objectives of the present invention include, for example, providing a method for treating deformation of steeply inclined phyllite, which proposes that the vault and the side wall adopt different reserved deformation amounts, which conforms to the on-site surrounding rock deformation convergence law and can avoid the right wall from becoming unstable and collapsing due to the superimposed gravity effect under the condition of blasting disturbance.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] The present invention proposes a deformation treatment method for steeply inclined phyllite, comprising:

[0007] Excavate the tunnel body, and design the reserved deformation between the initial support and the secondary lining, wherein the tunnel body includes a vault and a side wall, the reserved deformation of the vault is S1, and the reserved deformation of the side wall is S2, where S1 is less than S2;

[0008] Initial support and secondary lining are carried out in the tunnel body.

[0009] Optionally, the range of S1 is 14-16 cm, and the range of S2 is 7-9 cm.

[0010] Optionally, the initial support includes an arch frame and locking feet, and at least four locking feet are driven into the surrounding rock along the side wall.

[0011] Optionally, at least four of the locking pins are spaced 15° apart, and the locking pins use a small grouting tube with a length of at least 4.5 m.

[0012] Optionally, the method comprises: performing smooth blasting on the tunnel body.

[0013] Optionally, peripheral blastholes and first spacings between the peripheral blastholes, auxiliary blastholes and second spacings between the auxiliary blastholes are determined based on surrounding rock feature information of the tunnel body, and an excavation contour line of the tunnel body is confirmed.

[0014] Optionally, the first spacing is 40-50 cm.

[0015] Optionally, the depth of the peripheral blastholes does not exceed the excavation contour line, and the peripheral blastholes include long holes and short holes arranged at intervals, the depth of the long holes is 3-3.5m, the depth of the short holes is 1.5-1.7m, and the apertures of the long holes and the short holes are 40-46mm.

[0016] Optionally, the side wall includes a left wall and a right wall;

[0017] The depth of the peripheral blastholes of the right wall is 20 cm inward along the excavation contour line, and the charge amount of the peripheral blastholes of the right wall is 0.4 kg / m.

[0018] Optionally, the peripheral blastholes and the auxiliary blastholes are charged with charge at intervals of at least 0.5 m, and gun mud is used to plug the holes within 0.3 m from the peripheral blastholes and the auxiliary blastholes.

[0019] The beneficial effects of the embodiments of the present invention include, for example:

[0020] The deformation treatment method of steeply inclined phyllite proposed in the present invention, through comprehensive analysis of geological survey and monitoring measurement, clarifies the heterogeneous deformation mechanism of surrounding rock after excavation, and proposes that the vault and side walls adopt different reserved deformation amounts, which conforms to the on-site surrounding rock deformation convergence law; thereby avoiding the instability and collapse of the right wall due to the superimposed gravity under the condition of blasting disturbance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 It is a schematic diagram of the arrangement of peripheral blastholes and auxiliary blastholes in an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the peripheral blasthole interval charging in an embodiment of the present invention;

[0024] Figure 3 Schematic diagram of a long hole and a short hole in an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of a tunnel body according to an embodiment of the present invention;

[0026] Figure 5 It is a schematic diagram of the reserved deformation amount after the initial support and the secondary lining are adjusted in an embodiment of the present invention;

[0027] Figure 6 It is a structural schematic diagram of the initial support in an embodiment of the present invention.

[0028] Icons: 010-tunnel body; 011-vault; 012-left wall; 013-right wall; 100-primary support; 110-arch frame; 120-locking foot; 200-secondary lining; 300-peripheral blastholes; 310-first spacing; 320-auxiliary blastholes; 340-second spacing; 400-explosive; 410-detonator; 420-detonating cord; 500-contour line; 600-drill rod. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0034] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0035] At present, a tunnel in a certain place is a double-hole four-lane highway tunnel. The geology of the tunnel site is mainly sericite phyllite, and some parts are sandy sericite phyllite. The maximum burial depth of the tunnel is 415m. The rock foliation is 312~350°∠64~86°, and it is partially reversed, but the trend is basically stable. The rock mass is fragmented structure~medium and thin layered structure under the cutting of layers and joints. The basic seismic peak acceleration is 0.20g, and the basic seismic acceleration response spectrum characteristic period is 0.40s, corresponding to the basic earthquake intensity VIII.

[0036] The climate in this area is warm and humid, with abundant rainfall. Most of the atmospheric precipitation flows into rivers and streams in the form of surface runoff, or seeps into bedrock cracks. The regional groundwater types are mainly loose pore water and bedrock pores and cracks. The groundwater is generally low-mineral fresh water, which is suitable for engineering water and slightly corrosive to concrete and steel structures. The tunnel design surrounding rock level is V and IV. The support parameters for the IV surrounding rock section are Z4a and Z4b, among which the Z4b lining parameters are Φ22 drug coil anchor rod 250cm, Φ6.5 steel mesh @25*25cm, I16 I-beam steel frame @100cm / frame, C25 sprayed concrete 22cm, reserved deformation 8cm, waterproof layer, C30 concrete 40cm (secondary lining without steel bars).

[0037] During the construction process, the Z4b type lining section showed large horizontal convergence deformation of the initial support 100, and the initial support 100 side wall horizontal longitudinal cracks and local intrusion, which affected the subsequent secondary lining construction. The owner organized the design unit and geological and tunneling experts to conduct on-site investigation and demonstration, carried out ground stress testing, adjusted lining parameters, and after repeated on-site tests, finally determined the initial support 100 construction method suitable for steep phyllite tunnels.

[0038] Please refer to Figure 1-Figure 6 This embodiment provides a method for treating deformation of steeply inclined phyllite, comprising:

[0039] The tunnel body 010 is excavated, and the reserved deformation between the initial support 100 and the secondary lining 200 is designed. The tunnel body 010 includes the vault 011 and the side wall. The reserved deformation of the vault 011 is S1, and the reserved deformation of the side wall is S2, and S1 is less than S2.

[0040] Initial support 100 and secondary lining 200 are carried out in the tunnel body 010 .

[0041] It is understandable that the traditional concept is to use a uniform deformation amount for the reserved deformation after tunnel excavation according to the different grades of surrounding rock. The present invention, through comprehensive analysis of geological survey and monitoring measurement, clarifies the heterogeneous deformation mechanism of surrounding rock after excavation, and proposes that the vault 011 and the side wall use different reserved deformation amounts, which conforms to the on-site surrounding rock deformation convergence law; thereby avoiding the instability and collapse of the right wall 013 under the condition of blasting disturbance and the superposition of gravity.

[0042] In this embodiment, a method for treating deformation of steeply inclined phyllite includes:

[0043] S1: Conduct geological surveys to understand the occurrence of rock strata.

[0044] S2: Perform smooth blasting on the tunnel body 010.

[0045] S3: Excavate the tunnel body 010 and design the reserved deformation between the initial support 100 and the secondary lining 200. The tunnel body 010 includes the vault 011 and the side wall. The reserved deformation of the vault 011 is S1, and the reserved deformation of the side wall is S2. S1 is less than S2.

[0046] S4: Perform initial support 100 and secondary lining 200 in the tunnel body 010.

[0047] Please refer to Figure 4In this embodiment, regarding S1, it can be understood that first, a detailed investigation of the geological conditions of the surrounding rock of the face is conducted, a geological sketch is drawn, the rock formation strike and inclination are mastered, and the surrounding rock grade is determined to be consistent with the design. According to the geological forecast results, the rock formation strike of this tunnel intersects with the tunnel axis at a small angle, and is basically parallel in some parts, and the surrounding rock inclination varies from 70° to 80°. The surrounding rock is strongly weathered sericite phyllite, the surrounding rock grade is IV, thin-layered, the rock mass is broken, the rock quality is relatively soft, and the rock mass integrity is poor.

[0048] After the arch 011 is excavated, it is relatively stable, the left wall 012 is under-excavated frequently, and the right wall 013 is over-excavated frequently. This is mainly because the surrounding rock loses support after the excavation of the right wall 013, and is prone to instability and collapse under the blasting disturbance and gravity. After adopting S1 of the present invention, the smooth blasting effect is good, the convergence deformation of the initial support 100 of the tunnel is significantly controlled, and the deformation intrusion problem of the initial support 100 does not occur in the subsequent construction.

[0049] Please refer to Figure 1-Figure 3 In this embodiment, S2 further includes the following steps:

[0050] S21: Determine the peripheral blastholes 300 and the first spacing 310 of the peripheral blastholes 300, the auxiliary blastholes 320 and the second spacing 340 of the auxiliary blastholes 320 according to the surrounding rock feature information of the tunnel body 010, and confirm the excavation contour line 500 of the tunnel body 010.

[0051] The first spacing 310 of the peripheral blastholes 300 is 40 cm. Of course, the first spacing 310 can also be 45 cm, 46 cm, 47 cm, 48 cm, 49 cm and 50 cm.

[0052] S22: The depth of the peripheral blastholes 300 does not exceed the excavation contour line 500, and the peripheral blastholes 300 include long holes and short holes arranged at intervals, the depth of the long holes is 3-3.5m, the depth of the short holes is 1.5-1.7m, and the apertures of the long holes and short holes are 40-46mm. The external insertion angle of the drilling rod 600 is 3°-6°.

[0053] Among them, the depth of the long hole is 3.2m, the depth of the short hole is 1.6m, and the aperture of the long hole and the short hole is 42mm.

[0054] Of course, the depth of the long hole can also be 3m, 3.1m, 3.3m, 3.4m and 3.5m, the depth of the short hole can be 1.5m and 1.7m, and the apertures of the long hole and the short hole can be 40mm, 41mm, 43mm, 44mm, 45mm and 46mm.

[0055] The side walls include a left wall 012 and a right wall 013. Taking into account the adverse effects of the rock formation on the blasting surface, the holes around the arch 011 and the left wall 012 are arranged according to the normal excavation contour line 500; and the depth of the peripheral blast holes 300 of the right wall 013 is reduced by 20 cm inward along the excavation contour line 500. The charge amount of the peripheral blast holes 300 of the right wall 013 is 0.4 kg / m, which reduces the amount of explosives 400 and reduces the disturbance of the blasting to the right wall 013.

[0056] S23: The peripheral blastholes 300 and the auxiliary blastholes 320 are charged with charges at intervals of at least 0.5 m, and the holes within 0.3 m from the peripheral blastholes 300 and the auxiliary blastholes 320 are plugged with gun mud.

[0057] Among them, please refer to Figure 2 , No. 2 rock emulsion explosive 400 is used for on-site blasting. A detonator 410 is set in one of the blastholes, and the explosives 400 in each blasthole are connected through a detonating tube 420, so that the explosives 400 can simultaneously perform smooth blasting on the tunnel body 010.

[0058] It is understandable that the long hole is adjusted to a combination of long and short holes, the drilling method is optimized, the drilling position of the bottom plate hole is adjusted, and the construction efficiency is improved. At the same time, the long and short hole blasting better solves the problem of easy landslide when the right wall 013 of the steep phyllite is disturbed during blasting, and avoids over-excavation.

[0059] At the same time, by adjusting the drilling method and charging section, the over-excavation and under-excavation of the granite tunnel floor holes can be greatly reduced, saving tunnel base leveling concrete, with high economic benefits.

[0060] S24: Detonation is performed to carry out smooth surface blasting of the tunnel body 010.

[0061] Regarding S2, it is understandable that since the surrounding rock of the tunnel body 010 is sericite phyllite, which is thin-layered, the loose circle of the surrounding rock is large after blasting. Although the loose surrounding rock is cleaned during the slag discharge process, some of the loose surrounding rock will loosen and slide after the installation of the steel arch frame 110, thereby affecting the construction of the initial support 100. Some of the loose surrounding rock will continue to change in displacement after the initial support 100 concrete is sprayed, which is the main reason for the large horizontal convergence deformation of the initial support 100.

[0062] Therefore, the blasting parameters of the tunnel body 010 must be adjusted to improve the smooth blasting effect and reduce the disturbance to the original surrounding rock.

[0063] Specifically, regarding S3, the range of S1 is 14-16 cm, and the range of S2 is 7-9 cm.

[0064] In this embodiment, S1 is 15 cm and S2 is 8 cm.

[0065] In an optional embodiment, S1 may be 14 cm, 15 cm, or 16 cm, and S2 may be 7 cm, 8 cm, or 9 cm.

[0066] It is understandable that according to the analysis of monitoring and measurement results, the deformation law of surrounding rock is summarized and the reserved deformation is adjusted. According to the physical characteristics of surrounding rock and the monitoring and measurement results of tunnel, the settlement change of arch 011 is small, and the relative value of horizontal convergence change is large. The original design of 8cm reserved deformation of Grade IV surrounding rock is only applicable to arch 011, and the side wall range cannot meet the surrounding rock convergence deformation.

[0067] After analyzing the monitoring and measurement data, the average convergence deformation value of the side wall position is about 15cm. Therefore, the reserved deformation is adjusted to the arch 011 to maintain the original design of 8cm unchanged, and the side wall adjustment is increased to 15cm. This setting is more able to adapt to the convergence of the surrounding rock.

[0068] In this embodiment, regarding S4: Further, please refer to Figure 5 The initial support 100 includes an arch frame 110 and a locking foot 120. Four locking feet 120 are driven into the surrounding rock along the left and right side walls. The four locking feet 120 are spaced 15 degrees apart, and the locking feet 120 use a grouting small pipe with a length of at least 4.5m.

[0069] It is understandable that due to the long deformation time and slow deformation of the phyllite, the locking foot 120 is insufficient in strength to lock and support the steel arch frame 110, causing the steel arch frame 110 to sink and converge. The measures taken to strengthen the anchor pipes of the locking foot 120 have a significant effect on limiting the horizontal convergence deformation. The four 4.5m locking foot 120 anchor pipes on each side have a significant locking effect on the surrounding rock and the arch frame 110; thus, the locking foot 120 is strengthened to improve the stability of the arch frame 110.

[0070] Furthermore, the secondary lining steel bars were added to the secondary lining 200. Since the original design Z4b lining was plain concrete, affected by the long-term creep of the surrounding rock, cracks appeared in the secondary lining at the location where the side wall converged and deformed the most. According to expert analysis, the original design secondary lining support parameters were weak and could not resist long-term external force compression. In addition, the tunnel site was located in a seismic zone with high ground stress. The original surrounding rock stress was redistributed after tunnel excavation. Phyllite was a soft rock, and the surrounding rock grade was at Grade IV, so the secondary lining needed to be reinforced with steel bars.

[0071] Therefore, the measure of adding secondary lining reinforcement shows that it is not easy to use plain concrete secondary lining for Class IV soft phyllite tunnels. The use of reinforced concrete secondary lining can inhibit the creep of the surrounding rock of phyllite tunnels and prevent the initial support 100 convergence creep, ensuring the stability of the tunnel structure. This setting can improve the overall stiffness of the structure and avoid cracking of the secondary lining caused by phyllite creep.

[0072] In summary, the embodiments of the present invention provide a method for treating deformation of steeply inclined phyllite. In view of the characteristics of steeply inclined phyllite tunnels, such as large horizontal convergence, small arch crown 011 settlement, and large blasting loosening circle, the deformation of the initial support 100 is controlled by enlarging the horizontal reserved deformation, and smooth blasting with long and short blastholes can reduce the disturbance of the surrounding rock. The locking foot 120 anchor pipe is provided to increase the stability of the arch frame 110.

[0073] 1. The present invention is mainly aimed at the initial support 100 deformation treatment technology of steep sericite phyllite. It can only be used as a reference for rock formations with an inclination angle of less than 45°, and is not used as a construction basis. The convergence deformation mechanism of steep phyllite has been basically understood. The arch effect of the vault 011 is obvious, it is easy to excavate and form, and the settlement of the vault 011 is small. The horizontal convergence deformation of the side wall is large, and the support needs to be strengthened. The convergence deformation time of phyllite is long, and the second lining needs to be strengthened with reinforced concrete to prevent the second lining from cracking.

[0074] 2. The innovation is that the vault 011 and the side wall use different reserved deformations. The traditional concept is that the reserved deformation after tunnel excavation adopts a uniform deformation according to the surrounding rock grade. The present invention clarifies the heterogeneous deformation mechanism of the surrounding rock after excavation through comprehensive analysis of geological survey and monitoring measurement, and proposes that the vault 011 and the side wall use different reserved deformations, which conforms to the on-site surrounding rock deformation convergence law.

[0075] 3. The key point is to use long and short holes and interval charging in the peripheral holes of smooth blasting. The long and short holes disperse the concentration of charge better, and the blasting disturbance to the weak phyllite is small. After excavation, the arch 011 has the best smooth blasting effect. The left wall 012 is basically not under-excavated, and the over-excavation of the right wall 013 is well controlled. It fully solves the problem of excessive loosening of the surrounding rock caused by the original single-length blasthole and concentrated charging, and greatly reduces the convergence range of the surrounding rock.

[0076] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for treating deformation of steeply inclined phyllite, characterized in that: include: Excavate the tunnel body, and design the reserved deformation between the initial support and the secondary lining, wherein the tunnel body includes a vault and a side wall, the reserved deformation of the vault is S1, and the reserved deformation of the side wall is S2, where S1 is less than S2; Initial support and secondary lining are carried out in the tunnel body.

2. The method for treating deformation of steeply inclined phyllite according to claim 1, characterized in that: The range of S1 is 14-16 cm, and the range of S2 is 7-9 cm.

3. The method for treating deformation of steeply inclined phyllite according to claim 1, characterized in that: The initial support includes an arch frame and locking feet, and at least four locking feet are driven into the surrounding rock along the side wall.

4. The method for treating deformation of steeply inclined phyllite according to claim 3, characterized in that: At least four of the locking pins are spaced 15 degrees apart, and the locking pins use a small grouting tube with a length of at least 4.5m.

5. The method for treating deformation of steeply inclined phyllite according to claim 3, characterized in that: include: The tunnel body is subjected to smooth blasting.

6. The method for treating deformation of steeply inclined phyllite according to claim 5, characterized in that: The peripheral blastholes and the first spacing between the peripheral blastholes, the auxiliary blastholes and the second spacing between the auxiliary blastholes are determined according to the surrounding rock feature information of the tunnel body, and the excavation contour line of the tunnel body is confirmed.

7. The method for treating deformation of steeply inclined phyllite according to claim 6, characterized in that: The first distance is 40-50 cm.

8. The method for treating deformation of steeply inclined phyllite according to claim 6, characterized in that: The depth of the peripheral blastholes does not exceed the excavation contour line, and the peripheral blastholes include long holes and short holes arranged at intervals. The depth of the long holes is 3-3.5m, the depth of the short holes is 1.5-1.7m, and the apertures of the long holes and the short holes are 40-46mm.

9. The method for treating deformation of steeply inclined phyllite according to claim 8, characterized in that: The side walls include a left wall and a right wall; The depth of the peripheral blastholes of the right wall is 20 cm inward along the excavation contour line, and the charge amount of the peripheral blastholes of the right wall is 0.4 kg / m.

10. The method for treating deformation of steeply inclined phyllite according to claim 6, characterized in that: The peripheral blastholes and the auxiliary blastholes are charged with charge at intervals of at least 0.5 m, and gun mud is used to plug the holes within 0.3 m from the peripheral blastholes and the auxiliary blastholes.

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