Yield-type support method for tunnels

Abstract

The invention discloses a yield type support method for a tunnel, comprising the following steps: A. judging whether a tunnel to be supported belongs to a reverse fault, and if so, performing subsequent steps; if not, constructing according to construction standards; B. determining a convergence area of ​​the reverse fault; C. determining a convergence size D of the convergence area; D. arranging a support structure for the convergence area, and determining a pre-support angle α of the support structure according to the convergence size; a convergence size not exceeding 20 cm corresponds to a pre-support angle α of 3°-5°, and a convergence size exceeding 20 cm corresponds to a pre-support angle α of 5°-10°, and the pre-support angle α does not exceed 10°; E. completing support design for the tunnel to be supported according to the determined pre-support angle α; F. completing support for the tunnel to be supported according to the support design construction; the invention can realize passing through an extrudable and extremely broken surrounding rock section at a faster construction speed, and the construction progress is not exchanged at the cost of sacrificing construction safety, and the arch frame dismantling and replacement caused by large deformation of the initial support is avoided, thereby reducing the construction cost, construction period and safety risks.

Description

Technical Field

[0001] The invention relates to the field of tunnel construction, and in particular to a yielding type support method for a tunnel. Background Art

[0002] Based on the fault fracture zones encountered in the tunnel's surrounding rock, especially the reverse fault sections dominated by compressive surrounding rock, the contact area between two or more surrounding rocks often shows strong compressive crushing phenomenon, forming breccia. In addition, the surrounding rock in different parts of the same section has different degrees of weakness, which brings great challenges to construction and excavation, and deformation and arch replacement phenomena occur frequently.

[0003] The usual method is to use large pipe sheds for advance support, large locking feet to constrain the convergence and deformation of the surrounding rock, and increase the size of steel frame connecting plates, meshes, and connecting bars to enhance the ability of the initial support to resist deformation. However, this type of reinforcement lacks specificity and cannot adapt well to complex and changeable geological conditions. Many tunnels are still completed by dismantling and replacing supports at the expense of safety, cost and construction period. There are currently no major breakthroughs and innovations on some key issues on how to deal with the compressive deformation of weak surrounding rocks, which has a great impact on the overall progress of tunnel projects.

[0004] Therefore, in order to solve the above problems, a compression-type support method for tunnels is needed, which can achieve a faster construction speed through the extrudable and extremely broken surrounding rock sections, without sacrificing construction safety in exchange for construction progress, avoiding the arch frame replacement caused by large deformation of the initial support, and reducing construction costs, construction period and safety risks. Summary of the invention

[0005] In view of this, the purpose of the present invention is to overcome the defects in the prior art and provide a compression type support method for tunnels, which can achieve a faster construction speed through the extrudable and extremely broken surrounding rock sections, without sacrificing construction safety in exchange for construction progress, avoiding the replacement of arch frames due to large deformation of initial support, and reducing construction costs, construction period and safety risks.

[0006] The yield type support method for a tunnel of the present invention comprises the following steps:

[0007] A. Determine whether the tunnel to be supported belongs to a reverse fault. If so, proceed to the subsequent steps; if not, construct according to the construction standards;

[0008] B. Determine the convergence area of ​​reverse faults;

[0009] C. Determine the convergence size D of the convergence area;

[0010] D. Support structure members are set in the convergence area, and the pre-support angle α of the support structure members is determined according to the convergence size; the convergence size not exceeding 20cm corresponds to a pre-support angle α of 3°-5°, and the convergence size exceeding 20cm corresponds to a pre-support angle α of 5°-10°, and the pre-support angle α does not exceed 10°;

[0011] E. Complete the support design of the tunnel to be supported according to the determined pre-support angle α;

[0012] F. Complete the support of the tunnel to be supported according to the support design and construction.

[0013] Further, step A includes step A 1 The methods for determining the tunnels to be supported include obtaining advanced geological forecast data and obtaining data on the characteristics of the surrounding rock in the area to be constructed.

[0014] Further, step A also includes step A 2 .According to step A 1 The data provide a preliminary estimate of the changing trend of the surrounding rock ahead.

[0015] Further, step A also includes step A 3 .Verification Step A 2 Whether the change trend of the surrounding rock in the middle and front is consistent with the preliminary judgment of the change trend of the surrounding rock in the front; if so, proceed to the subsequent steps; if not, construct according to the construction standards.

[0016] Further, in step D, the convergence dimension not exceeding 10 cm corresponds to a 3° pre-support angle α, the convergence dimension exceeding 10 cm but not exceeding 20 cm corresponds to a 5° pre-support angle α, the convergence dimension exceeding 20 cm but not exceeding 30 cm corresponds to an 8° pre-support angle α, and the convergence dimension exceeding 30 cm but not exceeding 50 cm corresponds to a 10° pre-support angle α.

[0017] Furthermore, the convergence size is the maximum convergence amount of the convergence area along the horizontal direction in the initial branch state of the tunnel.

[0018] Furthermore, the supporting structure is a steel frame connecting plate, the middle part of the steel frame connecting plate is bent to form an outward protrusion, and when the steel frame connecting plate is placed horizontally, the angle between the tangent line of the outer edge of the steel frame connecting plate and the horizontal line is the pre-support angle α.

[0019] Furthermore, the tunnel to be supported has a center line, and after the steel frame connecting plate forms support for the tunnel to be supported, the center of the steel frame connecting plate is located on the center line of the tunnel to be supported.

[0020] The beneficial effects of the present invention are as follows: the yielding type support method for tunnels disclosed by the present invention has good construction continuity and high construction efficiency, avoids the reduction of efficiency caused by frequent adjustment of construction methods under complex and changeable geological conditions, and can better adapt to the extrusion surrounding rock with convergence deformation as the main feature; it has strong pertinence, and according to the stress state and characteristics of the initial support, measures such as optimizing the section and setting up steel frame connecting plates to connect deformation units are adopted to achieve the purpose of quickly passing through extremely broken surrounding rock sections; it has a high safety principle, and this technology is a targeted improvement of conventional tunnel construction technology and measures, and does not sacrifice construction safety in exchange for construction progress. It avoids the replacement of arch frames caused by large deformation of the initial support, and reduces construction costs, construction period and safety risks; it has a strong applicability principle, and has a strong reference significance for the construction of tunnels in interlayered surrounding rocks and broken zones under asymmetric conditions caused by layer bias, extrusion surrounding rocks and regional structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Figure 2 It is a structural schematic diagram of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of the support structure installation in which the pre-support angle α is within the range of 3°-5° according to the present invention;

[0025] Figure 4 This is a schematic diagram of the structure of the support structure installation of the present invention when the pre-support angle α is in the range of 5°-10°. DETAILED DESCRIPTION

[0026] Figure 1 The structural schematic diagram of the present invention is shown in the figure. As shown in the figure, the yield type support method for a tunnel in this embodiment includes the following steps:

[0027] A. Determine whether the tunnel to be supported belongs to a reverse fault. If so, proceed to the subsequent steps; if not, construct according to the construction standards;

[0028] Step A includes step A 1 . The method of judging the tunnel to be supported includes obtaining advanced geological prediction data and obtaining surrounding rock characteristics data of the area to be constructed; obtaining advanced geological prediction data and obtaining surrounding rock characteristics data of the area to be constructed can be achieved by using any detection equipment and device of the existing technology, and this scheme will not be repeated;

[0029] Step A also includes step A 2 .According to step A 1The data is used to preliminarily judge the changing trend of the surrounding rock ahead; the changing trend of the surrounding rock ahead is judged by any detection equipment and device in the existing technology, which is a common technical means in this field and will not be described in detail here;

[0030] Step A also includes step A 3 .Verification Step A 2 Whether the change trend of the surrounding rock in the front is consistent with the preliminary judgment of the change trend of the surrounding rock in the front; this step requires manual comparison of whether the two sets of information are consistent. The judgment standard is determined according to the on-site construction standard and will not be repeated here; if yes, proceed to the subsequent steps, if not, construct according to the construction standard; this scheme is only applied to the support of reverse faults. If the surrounding rock in the front is judged not to be a reverse fault, continue to construct according to the construction standard, which will not be repeated here;

[0031] B. Determine the convergence area of ​​the reverse fault; the convergence area is the settlement area where the reverse fault spreads inward after the initial support;

[0032] C. Determine the convergence dimension D of the convergence area; the convergence dimension is the maximum convergence amount of the convergence area in the horizontal direction in the initial support state of the tunnel; the horizontal direction is the horizontal direction in the figure;

[0033] D. Support structure members are arranged in the convergence area, and the pre-support angle α of the support structure members is determined according to the convergence size; the convergence size not exceeding 20 cm corresponds to a pre-support angle α of 3°-5°, and the convergence size exceeding 20 cm corresponds to a pre-support angle α of 5°-10°, and the pre-support angle α does not exceed 10°; in step D, the convergence size not exceeding 10 cm corresponds to a pre-support angle α of 3°, the convergence size exceeding 10 cm but not exceeding 20 cm corresponds to a pre-support angle α of 5°, the convergence size exceeding 20 cm but not exceeding 30 cm corresponds to a pre-support angle α of 8°, and the convergence size exceeding 30 cm but not exceeding 50 cm corresponds to a pre-support angle α of 10°; so that the support structure members can converge inward according to the predetermined convergence size, and complete the reasonable support of the support tunnel;

[0034] E. completing the support design of the tunnel to be supported according to the determined pre-support angle α; the support design includes but is not limited to drawing and calculating the convergence size of the preset convergence area, which will not be repeated here;

[0035] F. Complete the support of the tunnel to be supported according to the support design and construction.

[0036] In this embodiment, the supporting structure is a steel frame connecting plate 1, the middle part of the steel frame connecting plate 1 is bent to form an outward protrusion, and when the steel frame connecting plate 1 is placed horizontally, the angle between the tangent line of the outer edge of the steel frame connecting plate 1 and the horizontal line is the pre-support angle α. Figure 2The cantilever structure shown is fixed on one side. The cantilever end serves as a free end to support the convergence area. When the convergence area converges, the cantilever end is pressed inward until it is completely converged to form support for the tunnel. Figure 3 and Figure 4 They correspond to the support state of 5°-10° pre-support angle α and the support state of 3°-5° pre-support angle α respectively; when the pre-support angle α is larger, the cantilever single-side fixing method can be adopted, and when the pre-support angle α is smaller, both ends of the supporting structure will be fixed.

[0037] In this embodiment, the tunnel to be supported has a center line, and after the steel frame connecting plate 1 forms support for the tunnel to be supported, the center of the steel frame connecting plate 1 is located on the center line of the tunnel to be supported. This allows the steel frame connecting plate 1 to converge and press to a preset position according to a predetermined preset position, thereby improving the support effect;

[0038] The present invention relates to a deformation prevention and control technology for initial support construction of tunnels with unfavorable geological conditions, specifically, for tunnel construction crossing a section where a reverse fault compressive bedding surrounding rock contacts a crushing zone. By studying the deformation and stress characteristics of the tunnel under such conditions, based on the concept of yielding support, a steel frame connecting plate 1 type yielding support method for initial support of the tunnel under asymmetric compressive conditions is adopted; for sections of tunnels with extremely crushed surrounding rock with compressive properties, by analyzing monitoring measurement data and cross-sectional diagrams, a yielding support structure is realized by optimizing the cross-sectional structure and using a steel frame connecting plate 1 pre-support angle α, thereby achieving the effect of resisting deformation of the initial support of the tunnel, avoiding the cost increase caused by excessive measures or excessive reserved deformation, and improving the construction progress.

[0039] In a specific implementation method, for the construction of weak surrounding rock sections, the monitoring and measurement frequency is strengthened, and the detection data and the initial support cross-section diagram are analyzed in time. According to the deformation amount and deformation area, the pre-support angle α of the steel frame connecting plate 1 and the optimized cross-section size of the local enlarged area are determined, and finally a written processing drawing of the steel frame connecting plate 1 is formed. The steel frame connecting plate 1 processing plant performs precise processing according to the processing drawing to form the required steel frame connecting plate 1 with the pre-support angle α; when the tunnel is excavated, the layout is carried out according to the optimized cross-section size of the local enlarged area to ensure that the installation requirements of the optimized steel frame connecting plate 1 are met;

[0040] When installing the steel frame connecting plate 1, the pre-support angle α of the steel frame connecting plate 1 is used as a deformation unit equivalent to the retractable steel frame connecting plate 1 joint; the left upper and middle step steel frame connecting plate 1 is used as the cantilever end, and the local enlarged area is used as the yield unit, allowing it to deform within a reasonable space; the pre-support angle α of the steel frame connecting plate 1 and the optimized cross-sectional dimensions of the local enlarged area are determined according to the surrounding rock and monitoring measurements; the "outward opening" end of the steel frame connecting plate 1 is fixed with an extended high-strength bolt, and the upper and lower connecting plates are vertically welded with 2 to 4 Ф22 threaded steel bars to form; as the steel frame connecting plate 1 gradually deforms, the vertically welded threaded steel bars will deform accordingly, and the upper and lower connecting plates will gradually "close their mouths" until they are tightly fitted.

[0041] This method has good construction continuity and high construction efficiency. It avoids the reduction of efficiency caused by frequent adjustment of construction methods under complex and changeable geological conditions, and can better adapt to the extrusion surrounding rock with convergence deformation as the main feature. It has strong pertinence. According to the stress state and characteristics of the initial support, it adopts measures such as optimizing the section and setting a steel frame connecting plate 1 to connect the deformation unit to achieve the purpose of quickly passing through the extremely broken surrounding rock section. It has high safety principle. This technology is a targeted improvement of conventional tunnel construction technology and measures. It does not sacrifice construction safety in exchange for construction progress. It avoids the replacement of arch frames caused by large deformation of initial support, and reduces construction costs, construction period and safety risks. It has strong applicability principle. It has strong reference significance for the construction of tunnels in interlayered surrounding rocks and broken zones under asymmetric conditions caused by bedding bias, extrusion surrounding rocks and regional structures.

[0042] The type 1 yielding support method for the tunnel steel frame connecting plate is based on the advanced geological forecast data and the surrounding rock characteristics revealed by the construction, and the surrounding rock integrity, occurrence and inclination are used to predict the change trend of the surrounding rock ahead; the prediction is verified by adding geophysical exploration and drilling measures, such as geological radar, transient electromagnetic method, long drilling, etc., and the connection plate pre-support angle α of the optimized steel frame connecting plate 1 and the optimized cross-section size of the local enlarged area are determined based on the monitoring measurement data and the initial support section measurement data, and the impact analysis of the engineering construction;

[0043] During the construction of a railway tunnel crossing a reverse fault squeezing bedding surrounding rock contact crushing zone section, the present invention can achieve passing through the squeezing extremely crushing surrounding rock section at a faster speed; targeted improvements are made to conventional tunnel construction methods and strengthening measures, and construction progress is not exchanged at the cost of sacrificing construction safety; the present invention has the characteristics of good construction continuity, high construction efficiency, strong targeting and high safety, and has a strong reference significance for tunnel construction with similar situations.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A yield type support method for a tunnel, characterized in that: The steps include: A. Determine whether the tunnel to be supported belongs to a reverse fault. If so, proceed to the subsequent steps; if not, construct according to the construction standards; B. Determine the convergence area of ​​reverse faults; C. Determine the convergence size D of the convergence area; D. Support structure members are set in the convergence area, and the pre-support angle α of the support structure members is determined according to the convergence size; the convergence size not exceeding 20cm corresponds to a pre-support angle α of 3°-5°, and the convergence size exceeding 20cm corresponds to a pre-support angle α of 5°-10°, and the pre-support angle α does not exceed 10°; The supporting structure is a steel frame connecting plate, the middle part of the steel frame connecting plate is bent to form an outward bulge, and when the steel frame connecting plate is placed horizontally, the angle between the tangent line of the outer edge of the steel frame connecting plate and the horizontal line is the pre-support angle α; E. Complete the support design of the tunnel to be supported according to the determined pre-support angle α; F. Complete the support of the tunnel to be supported according to the support design and construction.

2. The yield type support method for tunnel according to claim 1, characterized in that: Step A includes step A1. The method of determining the tunnel to be supported includes obtaining advanced geological prediction data and obtaining surrounding rock characteristics data of the area to be constructed.

3. The yield type support method for tunnel according to claim 2, characterized in that: Step A also includes step A2. Preliminarily determine the changing trend of the surrounding rock ahead based on the data from step A1.

4. The yield type support method for tunnel according to claim 3, characterized in that: Step A also includes step A3. Verifying whether the changing trend of the surrounding rock ahead in step A2 is consistent with the preliminarily determined changing trend of the surrounding rock ahead; if so, proceed to the subsequent steps; if not, perform construction according to the construction standards.

5. The yield type support method for tunnel according to claim 1, characterized in that: In step D, the convergence dimension not exceeding 10 cm corresponds to a 3° advance support angle α, the convergence dimension exceeding 10 cm but not exceeding 20 cm corresponds to a 5° advance support angle α, the convergence dimension exceeding 20 cm but not exceeding 30 cm corresponds to an 8° advance support angle α, and the convergence dimension exceeding 30 cm but not exceeding 50 cm corresponds to a 10° advance support angle α.

6. The yield type support method for tunnel according to claim 1, characterized in that: The convergence size is the maximum convergence amount of the convergence area along the horizontal direction in the initial branch state of the tunnel.

7. The yield type support method for tunnel according to claim 1, characterized in that: The tunnel to be supported has a center line. After the steel frame connecting plate forms support for the tunnel to be supported, the center of the steel frame connecting plate is located on the center line of the tunnel to be supported.

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