A dark excavation large-span column-free underground structure for rock and soil strata and a construction method thereof

Abstract

The invention discloses a dark-excavated large-span column-free underground structure and a construction method for rock-soil strata, and relates to the field of underground engineering technology. The method comprises the following steps: step S1, constructing a plurality of upper transverse guide holes longitudinally above a tunnel vault, using the upper transverse guide holes to preliminarily perform vertical or oblique reinforcement treatment on the rock-soil within the tunnel vault and side wall range, and after the reinforcement range reaches the strength requirement, constructing transverse connecting beams inside all the upper transverse guide holes, and reserving oblique holes in all the transverse connecting beams and all the upper transverse guide hole side walls; using the upper transverse guide holes, transverse connecting beams, transverse frame beams and two obliquely tensioned prestressed anchor cables, etc., the transverse guide holes and the structural members and rock-soil within the tunnel vault range are formed into a whole, the upper load is resisted, and the bending resistance of the overall force system is ensured, and the cohesion and internal friction angle of the rock-soil between the upper transverse guide holes and the transverse frames ensure the shear resistance of the overall force system.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering, and in particular to a dark-excavated large-span column-free underground structure for rock and soil strata and a construction method thereof. Background Art

[0002] In order to meet the special needs of underground space development, large-span and ultra-large-span column-free underground structures are being widely used in water conservancy, transportation, national defense and other fields. However, under grade IV and V surrounding rock or sand and gravel strata, large-span and ultra-large-span column-free underground structures are rarely used in China.

[0003] The prior art patent with publication number CN114370293A discloses a method for constructing a large-span column-free underground cavern using a super-strong prestressed structure. The patent uses super-strong prestressed anchor cables and longitudinal bearing beams to replace the middle rock columns to achieve a column-free large-span structure. However, the implementation of this method depends on the anchoring force provided by the super-strong prestressed anchor cables. Since the anchor cables need to be drilled from bottom to top in the cave, steel strands need to be placed, and anchoring section slurry needs to be filled, the implementation is difficult. It is also difficult to predict whether the anchor cables will fail, and even if they fail, it is difficult to replace them.

[0004] The prior art patent with publication number CN114320340A discloses a large-span column-free underground tunnel structure and method based on an advanced pilot tunnel and tension anchor cables. The patent utilizes several advanced longitudinal pilot tunnels above the tunnel, connecting beams on the pilot tunnel floor, and tension prestressed anchor cables between the connecting beams and the tunnel longitudinal beams to achieve advanced geological exposure, geological deformation monitoring, and column-free large-span structures. However, the patent is only applicable to hard rock formations of grades II to IV. The vertical spacing between the longitudinal pilot tunnel and the underground tunnel is greater than or equal to 10m, and considering the buried depth of the longitudinal pilot tunnel, the tunnel structure to which the patent belongs is often a deep-buried structure, and the height of lifting objects or personnel from the tunnel to the ground is relatively high.

[0005] In view of this, in view of the shortcomings and applicability limitations of the prior art, a large-span column-free underground structure and a construction method for a dark excavation in a rock and soil stratum are provided. Summary of the invention

[0006] The object of the present invention is to provide a large-span column-free underground structure and a construction method for use in rock and soil strata to solve the above-mentioned problems.

[0007] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0008] A construction method for a dark-excavated large-span column-free underground structure in a rock-soil stratum comprises the following steps:

[0009] Step S1, constructing a plurality of upper transverse guide tunnels longitudinally above the tunnel vault, using the upper transverse guide tunnels to perform vertical or oblique reinforcement treatment on the rock and soil within the tunnel vault and side wall range in advance, and after the reinforcement range reaches the strength requirement, constructing transverse connecting beams inside all the upper transverse guide tunnels, and reserving oblique holes in all the transverse connecting beams and all the upper transverse guide tunnel side walls;

[0010] Step S2, prestressed anchor cables are installed in the inclined holes reserved in all transverse connecting beams;

[0011] Step S3, longitudinally constructing a plurality of lower transverse guide holes arranged in an annular direction, and using the lower transverse guide holes to receive the prestressed anchor cables driven from the upper transverse guide holes;

[0012] Step S4, tensioning the prestressed anchor cables, and constructing the transverse frame beams from bottom to top, after tensioning the prestressed anchor cables to a predetermined strength, casting the transverse frame beams from bottom to top;

[0013] Step S5, using oblique tension prestressed anchor cables to connect the transverse connecting beam with the transverse frame beams on both sides;

[0014] Step S6, after the oblique connection between the transverse connecting beam and the transverse frame beam is completed, the upper transverse guide tunnel is used to reinforce the rock and soil above the vault between the transverse frame beams, the soil between the transverse frame beams is excavated, and the soil between the transverse frame beams of the tunnel is supported by lining, and finally the tunnel lining forms a closed and continuous underground large-span structure;

[0015] Step S7: During the use of the tunnel, tension monitoring is performed on all inclined prestressed anchor cables. If the tension monitoring value of the prestressed anchor cable is less than or equal to 90% of the prestressed design value or the daily change rate of the tension monitoring value of the prestressed anchor cable is greater than or equal to 5% of the prestressed design value, the use of the tunnel is suspended, and temporary vertical lifting measures are taken for the corresponding tension loss section using internal supports in a timely manner, and the prestressed anchor cables are replaced section by section.

[0016] As a preferred solution of the present invention, the number of the upper transverse guide holes is consistent with the number of the transverse frame beams.

[0017] As a preferred solution of the present invention, all the transverse connecting beams and all the transverse frame beams are arranged longitudinally staggered with equal intervals, and all the transverse connecting beams are located directly above two adjacent transverse frame beams.

[0018] As a preferred solution of the present invention, the transverse frame beam adopts an arch structure.

[0019] As a preferred solution of the present invention, in step S6, the support end is supported by the transverse frame beams on both sides, and the outer arch lining structure is constructed in a timely manner.

[0020] As a preferred solution of the present invention, the number of the oblique holes is set to multiple groups, and the multiple groups of oblique holes are arranged at equal intervals along the length direction of the transverse connecting beam.

[0021] As a preferred solution of the present invention, the number of each group of oblique holes is set to two, and each group of oblique holes is symmetrically arranged.

[0022] As a preferred solution of the present invention, the bottom ends of each pair of prestressed anchor cables are connected to the transverse frame beams adjacent to the ends thereof to form an eight-shaped shape.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention is suitable for deep and shallow buried large-span column-free underground structures in IV and V grade surrounding rocks or sand and gravel strata. The upper transverse guide tunnel, transverse connecting beams, transverse frame beams and two obliquely tensioned prestressed anchor cables are used to form an upper transverse guide tunnel and structural members and rock and soil bodies within the range of the tunnel arch to resist upper loads. The height between the upper transverse guide tunnel and the transverse frame beams ensures the bending resistance of the overall force system. The cohesion and internal friction angle of the rock and soil bodies between the upper transverse guide tunnel and the transverse frame beams are improved to ensure the shear resistance of the overall force system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0026] Figure 1 An overall structural schematic diagram of a dark excavation large-span column-free underground structure and a construction method for rock and soil strata is provided for an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the structure in step S4 is provided for an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of the construction structure in step S6 is provided for an embodiment of the present invention;

[0029] Figure 4 Provide a front view of the construction structure in step S6 for an embodiment of the present invention;

[0030] Figure 5 A side view of the construction structure in step S6 is provided for the embodiment of the present invention.

[0031] The numbers in the figure represent the following:

[0032] 1. Upper transverse guide hole; 2. Transverse connecting beam; 3. Oblique hole; 4. Lower transverse guide hole; 5. Prestressed anchor cable; 6. Transverse frame beam; 7. Support. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0034] like Figures 1 to 5 As shown, the present invention provides a construction method for a dark excavation large-span column-free underground structure in a rock and soil stratum, comprising the following steps:

[0035] Step S1, constructing a plurality of upper transverse guide tunnels 1 longitudinally above the tunnel vault, using the upper transverse guide tunnels 1 to perform vertical or oblique reinforcement treatment on the rock and soil within the tunnel vault and side wall range in advance, and constructing from top to bottom is more conducive to the reinforcement effect and controls the excavation risk. After the reinforcement range reaches the strength requirement, construct transverse connecting beams 2 inside all upper transverse guide tunnels 1, and reserve oblique holes 3 in all transverse connecting beams 2 and all upper transverse guide tunnel 1 side walls;

[0036] Step S2, prestressed anchor cables 5 are installed in the inclined holes 3 reserved in all transverse connecting beams 2;

[0037] Step S3, longitudinally constructing a plurality of lower transverse guide holes 4 arranged in an annular direction, and using the lower transverse guide holes 4 to receive the prestressed anchor cables 5 driven from the upper transverse guide holes 1;

[0038] Step S4, tensioning the prestressed anchor cable 5, and constructing the transverse frame beam 6 from bottom to top, after the prestressed anchor cable 5 is tensioned to a predetermined strength, the transverse frame beam 6 is cast from bottom to top; the number of the upper transverse guide holes 1 is consistent with the number of the transverse frame beams 6;

[0039] The upper transverse guide tunnel 1 and the transverse frame beam 6 together with the rock and soil between them form a component that bears the compression and bending stress in the cross section, thereby ensuring the bending resistance of the overall force system. The greater the height between the upper transverse guide tunnel 1 and the transverse frame beam 6, the higher the construction cost will be, but the cross-sectional inertia moment of the component will be greater, and it can withstand greater compression and bending stress. Therefore, according to the compression and shear calculation results, while meeting the force safety, the tunnel burial depth can be controlled, the lifting height between the tunnel and the ground can be shortened, and the lifting cost can be reduced;

[0040] All the transverse connecting beams 2 and all the transverse frame beams 6 are arranged longitudinally staggered with equal spacing, and all the transverse connecting beams 2 are located directly above two adjacent transverse frame beams 6;

[0041] The transverse frame beam 6 adopts an arch structure. The arch structure's compression and bending stress characteristics are utilized to the greatest extent to ensure the realization of a large-span tunnel. The transverse connecting beam 2 and the transverse frame beam 6 provide anchor points for both ends of the prestressed anchor cable 5, ensuring the integrity of the dark excavation large-span system.

[0042] Step S5, using oblique tension prestressed anchor cables 5 to connect the transverse connecting beam 2 with the transverse frame beams 6 on both sides; thereby enabling the rock and soil body sandwiched by the oblique tension prestressed anchor cables 5 and the transverse connecting beam 2 and the transverse frame beam 6 to bear the upper load as a whole;

[0043] Step S6, after the oblique connection between the transverse connecting beam 2 and the transverse frame beam 6 is completed, the upper transverse guide tunnel 1 is used to reinforce the rock and soil above the vault between the transverse frame beams 6, the soil between the transverse frame beams 6 is excavated, and the initial external arch and lining support 7 are performed, and finally the tunnel lining forms a closed, continuous underground large-span structure;

[0044] In step S6, the ends of the support 7 are supported by the transverse frame beams 6 on both sides, and the outer arch lining structure is promptly constructed, and the arch structure is used twice to resist the vertical and lateral earth pressure loads;

[0045] Step S7: During the use of the tunnel, tension monitoring is performed on all prestressed anchor cables 5. If the tension monitoring value of the prestressed anchor cable 5 is less than or equal to 90% of the prestressed design value or the daily rate of change of the tension monitoring value of the prestressed anchor cable 5 is greater than or equal to 5% of the prestressed design value, the use of the tunnel is suspended, and temporary vertical lifting measures are taken for the corresponding tension loss section using internal supports in a timely manner, and the prestressed anchor cables 5 are replaced section by section.

[0046] The present invention is applicable to deep and shallow buried large-span column-free underground structures in IV and V grade surrounding rock or gravel formations. The upper transverse guide tunnel 1, the transverse connecting beam 2, the transverse frame beam 6 and the two obliquely tensioned prestressed anchor cables are used to form an integral body with the structural components and rock and soil within the tunnel vault range to resist the upper load; and the vault structure of the dark-cut tunnel is closely combined with the covering soil of a certain depth through the upper transverse guide tunnel 1 and the prestressed anchor cable 5 to form a common load-bearing component. Compared with the vault structure of the dark-cut tunnel itself, the cross-sectional depth of the component is increased, thereby improving the bending strength. The internal friction and cohesion of the covering soil itself are used to achieve the purpose of improving the shear strength of the component. The advantage of the arch structure in compression and bending can be used to further increase the span of the underground structure. Based on the above three points, the dark-cut large-span tunnel can be constructed without columns under IV and V grade surrounding rock or gravel formations.

[0047] Compared with the prior art, the present application digs holes from top to bottom, places prestressed anchor cables, and fills anchor section slurry, which reduces the difficulty of implementation and makes it easy to ensure quality; and the present application can replace the prestressed anchor cables in the hole before they fail; and the prestressed anchor cables 5 of the present invention are set obliquely, and the transverse arrangement of the upper transverse guide hole 1 and the transverse connecting beam 2 and the longitudinal distribution of the lower transverse guide hole 4 and the transverse frame beam 6 form a transverse structural system, and the temporary (transverse connecting beam 2, prestressed anchor cables 5) and permanent (transverse frame beam 6) structures adopt a transverse structural system, which fully utilizes the shear resistance of the temporary and permanent structures and the rock and soil bodies sandwiched between the two to jointly resist vertical loads, and can be applied to both deeply buried rock and soil formations and shallowly buried rock and soil formations; compared with the longitudinal structure, the transverse structure in the present invention makes more full use of the arch effect jointly borne by the structure and the rock and soil body, which is more beneficial to safety and achieves the purpose of saving engineering costs.

[0048] The number of the oblique holes 3 is set to be multiple groups, and the multiple groups of oblique holes 3 are arranged at equal intervals along the length direction of the transverse connecting beam 2.

[0049] The number of each group of oblique holes 3 is set to two, and each group of oblique holes 3 is symmetrically arranged.

[0050] The bottom ends of each pair of prestressed anchor cables 5 are connected to the transverse frame beams 6 adjacent to their ends to form an eight-shaped shape.

[0051] The two prestressed anchor cables 5 are connected through the oblique holes 3 to form a symmetrical figure eight shape, so that each transverse connecting beam 2 is connected to the transverse frame beams 6 on both sides, thereby improving the integrity of the structural force.

[0052] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A construction method for a dark excavation large-span column-free underground structure in a rock and soil stratum, characterized in that: The steps include: Step S1, constructing a plurality of upper transverse guide tunnels (1) longitudinally above the tunnel vault, using the upper transverse guide tunnels (1) to perform vertical or oblique reinforcement treatment on the rock and soil within the tunnel vault and side wall range in advance, and after the reinforcement range reaches the strength requirement, constructing transverse connecting beams (2) inside all the upper transverse guide tunnels (1), and reserving oblique holes (3) in all the transverse connecting beams (2) and the side walls of all the upper transverse guide tunnels (1); Step S2, prestressed anchor cables (5) are installed in the inclined holes (3) reserved in all transverse connecting beams (2); Step S3, longitudinally constructing a plurality of lower transverse guide holes (4) arranged in an annular direction, and using the lower transverse guide holes (4) to receive the prestressed anchor cables (5) driven from the upper transverse guide holes (1); Step S4, tensioning the prestressed anchor cable (5), and constructing the transverse frame beam (6) from bottom to top, after the prestressed anchor cable (5) is tensioned to a predetermined strength, casting the transverse frame beam (6) from bottom to top; the transverse frame beam (6) adopts an arch structure; Step S5, using oblique tension prestressed anchor cables (5) to connect the transverse connecting beam (2) with the transverse frame beams (6) on both sides; Step S6, after the oblique connection between the transverse connecting beam (2) and the transverse frame beam (6) is completed, the upper transverse guide tunnel (1) is used to reinforce the rock and soil above the vault between the transverse frame beams (6), the soil between the transverse frame beams (6) is excavated, and the soil between the transverse frame beams (6) is supported by lining (7), and finally the tunnel lining forms a closed, continuous underground large-span structure; In step S6, the ends of the support (7) are supported by the transverse frame beams (6) on both sides, and the outer arch lining structure is promptly constructed; Step S7: During the use of the tunnel, all prestressed anchor cables (5) are subjected to tension monitoring. If the tension monitoring value of the prestressed anchor cable (5) is less than or equal to 90% of the prestressed design value or the daily rate of change of the tension monitoring value of the prestressed anchor cable (5) is greater than or equal to 5% of the prestressed design value, the use of the tunnel is suspended, and temporary vertical lifting measures are taken for the corresponding tension loss section using internal supports in a timely manner, and the prestressed anchor cables (5) are replaced section by section.

2. The construction method of a dark excavation large-span column-free underground structure for rock and soil strata according to claim 1 is characterized by: The number of the upper transverse guide holes (1) is consistent with the number of the transverse frame beams (6).

3. The construction method of a dark excavation large-span column-free underground structure for rock and soil strata according to claim 1 is characterized by: All the transverse connecting beams (2) and all the transverse frame beams (6) are arranged longitudinally staggered at equal intervals, and all the transverse connecting beams (2) are located directly above two adjacent transverse frame beams (6).

4. The construction method of a dark excavation large-span column-free underground structure for rock and soil strata according to claim 1 is characterized by: The number of the oblique holes (3) is set to be multiple groups, and the multiple groups of oblique holes (3) are arranged at equal intervals along the length direction of the transverse connecting beam (2).

5. The construction method of a dark excavation large-span column-free underground structure for rock and soil strata according to claim 4 is characterized in that: The number of each group of oblique holes (3) is set to two, and each group of oblique holes (3) is symmetrically arranged.

6. The construction method of a dark excavation large-span column-free underground structure for rock and soil strata according to claim 1 is characterized by: The bottom ends of each pair of prestressed anchor cables (5) are connected to the transverse frame beams (6) adjacent to the ends thereof to form an eight-shaped shape.

7. A large-span column-free underground structure for use in rock and soil formations, characterized in that: Obtained by the construction method described in any one of claims 1-6.

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