CN212272228U - Dense-net type advanced support system of underground excavation tunnel - Google Patents

Abstract

The dense-net type advanced support system for the underground excavated tunnel comprises grouting sleeve valve pipes and a pipe shed, wherein grouting is performed on a front tunnel face and surrounding rocks of subsequent excavation through the grouting sleeve valve pipes, then the dense-net type pipe shed is arranged to serve as a support, and the surrounding rocks at the top of an excavated section are supported through the pipe shed. And (4) arranging a small advanced guide pipe in the pipe shed gap, and reinforcing the rock and soil strength near the inner side surface of the tunnel through the small advanced guide pipe. The utility model discloses the undercut construction operation more suitable for sandy gravel stratum through adding close net formula pipe canopy and slip casting, has effectively utilized sandy gravel stratum self skeleton effect, compares the undercut engineering under the sandy gravel stratum in the past, the utility model discloses effectively controlled the stratum subside, has restricted the emergence of the super side condition of excavation, excavation length is not restricted in the construction simultaneously, has practiced thrift engineering cost, guarantees construction and peripheral building safety, provides the powerful guarantee for city undercut engineering safety construction.

Description

Dense-net type advanced support system of underground excavation tunnel

Technical Field

The utility model relates to an underground works technical field, more specifically says, in particular to secretly dig dense net formula advance support system in tunnel.

Background

With the rapid development of economy in China, underground engineering scales are rapidly expanded and connected into nets in order to adapt to the development and construction of modern cities. In order to avoid the influence on the ground environment and traffic, the underground excavation tunnel engineering is gradually the main construction method of urban underground engineering.

When underground excavation tunnel construction is carried out in a city, the situations of underpass of important building structures, existing subway lines, scenic spots, historic sites and the like are frequently met, so that extremely high requirements are put forward for stratum settlement control, and advance pre-support needs to be carried out on the underpass range before the underpass of underground excavation so as to realize settlement control.

At present, the existing underground excavation advance pre-supporting measures mainly comprise two measures: 1. the general method for the large pipe shed support construction comprises the following steps: before tunneling, a geological drilling machine is used for drilling horizontal holes in the vault area according to the designed hole number, space and depth, steel pipes with holes pre-drilled on the pipe walls are buried, and then cement slurry is injected to improve the rigidity of the steel pipes and reinforce soil; 2. the method is characterized in that the method comprises the steps of advancing small guide pipe support, wherein the advance small guide pipe support construction is similar to large pipe shed support construction, the method is suitable for underground excavation of a mine tunnel, and in the advance small guide pipe support construction, advanced grouting steel pipes are arranged at the arch crown every few steel frames according to design requirements.

The two forepoling forms are all that the vault of the tunnel is preformed into an umbrella-shaped structure, and the canopy frame supporting effect is achieved on the stratum. The large pipe shed and the advanced small conduit support are generally arranged at intervals of 250-350 mm in a circumferential direction, and the self rigidity of the steel pipe is utilized to support the upper surrounding rock and the load of the building structure. If an important building with a large load and a high requirement on settlement control is encountered, the pipe diameter of the pipe shed is often required to be increased or a multi-row pipe advancing mode is adopted, so that the problems of prolonged construction period, high use amount of advancing materials, poor supporting effect and the like are caused.

In summary, how to solve the problem of poor supporting effect of the single-form supporting method in the existing underground excavation advance pre-supporting measures under the use conditions of large load and high sedimentation control requirement becomes a problem to be solved urgently by the technical staff in the field.

SUMMERY OF THE UTILITY MODEL

In order to solve the problems in the prior art, the utility model provides a following technical scheme:

the utility model provides a close net formula advance support system in undercut tunnel the utility model discloses in, this close net formula advance support system in undercut tunnel's concrete structure as follows: a tunnel excavation contour line and a full-section deep-hole pre-grouting outer contour line are designed on the excavation section of the tunnel, and the tunnel excavation contour line is positioned in the full-section deep-hole pre-grouting outer contour line; the support system includes: one end of each grouting sleeve valve pipe is positioned on an excavation section, the other end of each grouting sleeve valve pipe extends towards the tunneling direction of the tunnel, and one end of each grouting sleeve valve pipe is distributed in the tunnel excavation contour line; and the pipe sheds are positioned between the tunnel excavation contour lines and the full-section deep-hole pre-grouting outer contour lines and form a dense-net type pipe shed.

Preferably, in the close-mesh type advance support system provided by the utility model, still include: the advanced small guide pipes are located between the tunnel excavation contour lines and the full-section deep-hole pre-grouting outer contour lines and used for reinforcing rock and soil close to the inner side face of the tunnel.

Preferably, in the dense-mesh type advanced support system provided by the present invention, a plurality of the pipe sheds are arranged at the periphery of the arc of the tunnel arch and form a single-row pipe shed; in the single-row pipe sheds, the distances from the pipe sheds to the arc of the arch part of the tunnel are the same; the single-row pipe shed is provided with at least two groups, the distance from the pipe shed to the arc of the tunnel arch in each single-row pipe shed is different, and the pipe sheds in the two adjacent groups of single-row pipe sheds are arranged in a staggered mode.

Preferably, in the close-mesh type advance support system provided by the utility model, still include and end the thick liquid wall, it sets up at the initiating terminal of each tunnelling section to end the thick liquid wall.

Preferably, one end of the pipe shed is fixedly connected with the grout stopping wall, and an included angle of 1-3 degrees is formed between the axis of the pipe shed and the central line of the tunnel.

Preferably, in the utility model provides an among the close net formula advance support system, still include the steelframe, the steelframe sets up along the tunnelling direction interval in tunnel in the tunnel that the excavation is good.

Preferably, one end of the advanced small guide pipe is located on an excavation section and takes the steel frame as a fulcrum, and an included angle of 15-25 degrees is formed between the axis of the advanced small guide pipe and the central line of the tunnel.

Preferably, in the close-mesh type advance support system provided by the utility model, in be provided with the steel reinforcement cage in the pipe canopy, in pipe canopy grout overflow hole has been seted up on the pipe canopy, pipe canopy grout overflow hole evenly lays on the pipe canopy, in little pipe grout overflow hole has been seted up on the little pipe of advance, little pipe grout overflow hole evenly lays on the little pipe of advance.

Preferably, the utility model provides an among the close net formula advance support system, the steel reinforcement cage is in including the steel reinforcement cage skeleton of pipe shape and setting reinforcing bar on the lateral surface of steel reinforcement cage skeleton, the reinforcing bar is provided with many, whole the reinforcing bar in equidistant setting on the lateral surface of steel reinforcement cage skeleton.

Preferably, in the utility model provides an among the close net formula advance support system, the one end of slip casting sleeve valve pipe is located end on the thick liquid wall slip casting sleeve valve pipe encircles the setting of tunnel central line interval, the one end of slip casting sleeve valve pipe is fixed, its other end for the setting is dispersed to the tunnel central line.

The utility model has the advantages as follows:

the utility model provides a close net formula advance support system in undercut tunnel, including slip casting sleeve valve pipe and pipe canopy, wherein, adopt slip casting sleeve valve pipe slip casting to consolidate the place ahead face and the country rock of follow-up excavation, later with manage to beat the pipe canopy of establishing the close net formula of multirow as strutting, support the country rock of excavating the section top through the pipe canopy. And (4) arranging a small advanced guide pipe in the pipe shed gap, and reinforcing the rock and soil strength near the inner side surface of the tunnel through the small advanced guide pipe. Compared with the prior art, the utility model discloses the undercut construction operation that more is applicable to the sandy gravel stratum through adding dense net formula pipe canopy and slip casting, has effectively utilized the self skeleton effect of sandy gravel stratum, compares the undercut engineering under the sandy gravel stratum in the past, the utility model discloses effectively controlled the stratum and subsided, restricted the emergence of the super side condition of excavation, excavation length is not restricted in the simultaneous construction, has practiced thrift engineering cost, guarantees construction and peripheral building safety, provides the powerful guarantee for city undercut engineering safety construction.

Drawings

The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. Wherein:

FIG. 1 is a schematic view of a section of a grouting area;

FIG. 2 is a schematic diagram of an arrangement mode of grouting sleeve valve pipes on an excavation section;

FIG. 3 is a longitudinal schematic view of a grouting sleeve valve tube arrangement;

fig. 4 is a schematic structural view of a single pipe shed in the present invention;

FIG. 5 is a schematic view of the arrangement of the middle pipe shed and the advanced small pipes in the excavation section;

FIG. 6 is a longitudinal view of the arrangement of the middle canopy and the leading small duct according to the present invention;

fig. 7 is a radial view of the reinforcement cage of the present invention;

fig. 8 is an axial view of the reinforcement cage of the present invention;

fig. 9 is a schematic view of the grouting range of grouting reinforcement when a building with five floors in the embodiment of the invention passes through;

fig. 10 is a schematic view of a grouting range of grouting reinforcement when a bridge is passed through in the embodiment of the present invention;

fig. 11 is a schematic view of the grouting range of grouting reinforcement when passing through the flood drainage channel according to the embodiment of the present invention;

description of reference numerals:

a grouting sleeve valve pipe 1, a steel frame 2, a pipe shed 3, a small advanced conduit 4, a pipe shed working chamber 5,

A reinforced steel plate 6, a drill 7, a reinforcement cage 8, a reinforcement cage framework 81, a reinforcement 82,

The full-section deep hole pre-grouting outer contour line 9, the tunnel excavation contour line 10, the grouting range 11,

A primary support 12 and a secondary lining support 13;

building a with five floors, bridge pile foundation b and flood drainage channel c.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments. Each example is provided by way of explanation of the invention and not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. It is therefore intended that the present invention encompass such modifications and variations as fall within the scope of the appended claims and equivalents thereof.

In the description of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description of the present invention and do not require that the present invention must be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense, and may be, for example, either fixed or detachable; they may be directly connected or indirectly connected through intermediate members, and specific meanings of the above terms will be understood by those skilled in the art as appropriate.

Please refer to fig. 1 to 11, wherein fig. 1 is a schematic diagram of a section of a grouting range; FIG. 2 is a schematic diagram of an arrangement mode of grouting sleeve valve pipes on an excavation section; FIG. 3 is a longitudinal schematic view of a grouting sleeve valve tube arrangement; fig. 4 is a schematic structural view of a single pipe shed in the present invention; FIG. 5 is a schematic view of the arrangement of the middle pipe shed and the advanced small pipes in the excavation section; FIG. 6 is a longitudinal view of the arrangement of the middle canopy and the leading small duct according to the present invention; fig. 7 is a radial view of the reinforcement cage of the present invention; fig. 8 is an axial view of the reinforcement cage of the present invention; fig. 9 is a schematic view of the grouting range of grouting reinforcement when a building with five floors in the embodiment of the invention passes through; fig. 10 is a schematic view of a grouting range of grouting reinforcement when a bridge is passed through in the embodiment of the present invention; fig. 11 is a schematic view of the grouting range of grouting reinforcement when the flood discharge channel is passed through in the embodiment of the present invention.

The scale of urban underground engineering is rapidly expanded and connected into a net, so that in order to avoid influences on ground environment and traffic, underground excavation tunnel engineering is increasingly used as a main construction method of urban underground engineering, the key problems to be solved by the underground excavation engineering are that the safety of the underground excavation construction is ensured, and the influence of the underground excavation engineering on surrounding building structures is reduced.

Therefore, the utility model discloses a close net formula advance support system in undercut tunnel. The utility model is suitable for an undercut engineering under the sandy cobble stratum, the utility model discloses can effectively stabilize the face (excavation section) in excavation face the place ahead through the slip casting mode, can also strut through the pipe shed 3 of establishing close net formula simultaneously, can provide support frame and slip casting for the stratum, utilize country rock self stability better. The small advanced guide pipe 4 is arranged below the support of the pipe shed 3 and in surrounding rocks between sheds to form a complete advanced support system, and pre-grouting reinforcement is carried out to ensure the stability of the excavation section structure and reduce overexcavation. Through practice proving, compare with current construction technical scheme, the utility model discloses practiced thrift engineering cost, strutted safe and reliable more.

For a better and detailed explanation of the invention, the following is made here: a tunnel excavation contour line 10 and a full-section deep-hole pre-grouting outer contour line 9 are designed on an excavation section of the tunnel, and the tunnel excavation contour line 10 is positioned in the full-section deep-hole pre-grouting outer contour line 9; the tunnel is excavated mechanically or manually, and the top of the tunnel is of an arc vault structure; the tunnel center line refers to a connecting line of the centers of circular arc vaults of vertical sections of the tunnel, and the length direction of the connecting line (the tunnel center line) is consistent with the depth direction of the tunnel.

The utility model provides a secretly dig close net formula advance support system in tunnel, specifically, the utility model provides a secretly dig close net formula advance support system in tunnel includes:

1. grouting sleeve valve pipe 1

Grouting sleeve valve pipe 1 is used for opening and digs the regional slip casting and consolidate, and 1 slip casting system of slip casting sleeve valve pipe is applicable to the undercut engineering, and it can control slip casting scope 11 and slip casting pressure, can also avoid the thick liquid backward flow simultaneously, guarantees construction quality.

In the utility model, the grouting sleeve valve pipe 1 adopts

Hard PVC pipe.

Specifically, the one end of slip casting sleeve valve pipe 1 is located the excavation section for with slip casting headtotail, pump into the concrete thick liquid through the slip casting system to slip casting sleeve valve pipe 1 internal pump, the other end of slip casting sleeve valve pipe 1 extends to the tunnelling direction in tunnel, the utility model discloses be provided with a plurality of slip casting sleeve valve pipes 1, a plurality of slip casting sleeve valve pipe 1 distribute in the tunnel excavation outline line.

The grouting sleeve valve pipe 1 is used for full-face grouting reinforcement in a full-face deep hole pre-grouting outer contour line 9, and the full-face grouting reinforcement range covers a tunnel excavation contour line 10.

The utility model discloses still be provided with only the thick liquid wall, only the thick liquid wall is used for cooperation slip casting sleeve valve pipe 1 to use. Specifically, the grout stopping wall is arranged at the starting end of the tunneling section and used for realizing water stopping and grout stopping before tunnel excavation and ensuring grouting reinforcement quality. In the tunnel excavation construction process, the tunnel is excavated in sections, the first grouting reinforcement is carried out when the first section of excavation is carried out, and a grout stopping wall is required to be used and is a plain concrete wall with the thickness of 300-500 mm. In the excavation of the subsequent section of the tunnel, the subsequent grouting operation utilizes the surrounding rock which is grouted in the range of about 3m from the tail end of the previous grouting reinforcement section as a grout stopping rock tray, and no additional grout stopping wall is needed.

Specifically, the grouting sleeve valve pipes 1 are arranged around the center line of the tunnel at intervals, one ends of the grouting sleeve valve pipes 1 are fixed, the other ends of the grouting sleeve valve pipes are arranged in a divergent mode relative to the center line of the tunnel, and the divergent structure of the grouting sleeve valve pipes 1 is similar to a spoke structure on an umbrella. The grouting sleeve valve pipes 1 are uniformly distributed on a plurality of circles with different radiuses, and the concrete arrangement of the grouting sleeve valve pipes 1 is subject to the guarantee that the farthest end grouting diffusion radiuses of the grouting sleeve valve pipes 1 can be pressed together. The grouting sleeve valve pipe 1 can be regarded as a cylinder, the diffusion radius of grouting is 1m, the farthest ends of the grouting sleeve valve pipe 1 are pressed together, and the pressing range is smaller as better.

Specifically, a grouting sleeve valve pipe is arranged at the center line of the tunnel, then the grouting sleeve valve pipes are arranged on a plurality of virtual circles with different radiuses by taking the grouting sleeve valve pipe as the center of a circle, and the radius values of all the virtual circles form a difference array from the first virtual circle to the outside. For example, the radius of the first virtual circle is 500mm, the radius of the second virtual circle is 1000mm, the radius of the third virtual circle is 1600mm, the radius of the fourth virtual circle is 2300mm, and the radius of the fifth virtual circle is 3100 mm. On each virtual circle, the grouting sleeve valve pipes 1 are arranged at equal intervals and consistent with the included angle between the central lines of the tunnels, so that the uniform pre-grouting reinforcement can be carried out in the outer contour lines of the section deep hole pre-grouting.

2. Pipe shed 3

The pipe shed 3 is provided to the tunnel upper portion, and can reinforce the tunnel upper structure. The vault of the tunnel is generally in a circular arc vault structure, and the structure (circular arc vault) can enable the vault of the tunnel to have better stress.

The utility model discloses in, pipe shed 3 sets up on the vault in tunnel for the region beyond the vault in tunnel is strutted and is consolidated.

Specifically, the pipe shed 3 is arranged along the excavation heading direction, namely the length direction of the pipe shed 3 is consistent with the tunneling direction of the tunnel, and the plurality of pipe sheds 3 are positioned between the tunnel excavation contour line and the full-section deep-hole pre-grouting outer contour line and form a dense-net type pipe shed.

Furthermore, a plurality of pipe sheds 3 are arranged on the periphery of the arc of the tunnel arch part to form a single-row pipe shed, circle center connecting lines of all single pipe sheds 3 in the single-row pipe shed in the same vertical section are arc lines, and on the same arc line, the circumferential distance between every two adjacent pipe sheds 3 is 0.5 m; in the single-row pipe shed, the distances from the pipe sheds 3 to the tunnel arch (the vertical section of the tunnel arch is in the shape of a circular arc) are the same; the single pipe canopy of multiunit is arranged the setting in proper order to the direction of keeping away from the tunnel center by the tunnel hunch portion, and single pipe canopy of row is provided with at least two sets ofly, and every group single pipe canopy of row forms pitch arc (centre of a circle connecting wire in same vertical section) to the distance of tunnel hunch portion circular arc vary, and the crisscross setting of single pipe canopy 3 of adjacent two sets of single pipe canopies. When more than two groups of single-row pipe sheds are arranged, the vertical distances between the arcs (circle center connecting lines in the same vertical section) formed by the two adjacent groups of single-row pipe sheds are equal.

Further, in the pipe shed support, one end of the pipe shed 3 is fixed, and the pipe shed 3 has an included angle of 1 to 3 degrees (such as 1 degree, 1 degree 20 degrees, 1 degree 30 degrees, 1 degree 40 degrees, 2 degrees 20 degrees, 2 degrees 40 degrees, 3 degrees) with the central line of the tunnel in space. The utility model discloses in, the contained angle that pipe shed 3 and tunnel central line had is 3 at the maximum, the contained angle selection is 1 to 3, preferably 1 ' -30, ensure that pipe shed 3 invades the tunnel excavation scope when beating to establish, and, if the angle of contained angle is too big between the central line of pipe shed 3 and tunnel, as the pipe shed is longer, then the soil between pipe shed and tunnel excavation supporting steel frame is just more, the soil volume is great then can't guarantee soil or rubble and do not take place the condition of whereabouts, if soil (rubble etc.) whereabouts, will appear overexciting and then arouse the backfill, consequently should make the pipe shed be close to excavation profile limit as far as possible, do not invade the excavation profile again simultaneously, combine designer's practical application and maintenance, have 1-3 contained angle scope between the central line of pipe shed 3 and tunnel.

In order to improve the structural strength of pipe shed 3, the utility model discloses be provided with the steel reinforcement cage in pipe shed 3, seted up pipe shed grout overflow hole on pipe shed 3, pipe shed grout overflow hole evenly lays on pipe shed 3, has seted up little pipe grout overflow hole on leading little pipe 4, and little pipe grout overflow hole evenly lays on leading little pipe 4.

Dense net type pipe shed 3 support and adopt

The seamless steel pipe of wall thickness 10mm, in same row, the hoop interval between two adjacent pipe sheds 3 is 500mm, and the length of pipe shed 3 is 35 m. The pipe shed 3 is formed by connecting a plurality of sections of steel pipes, two adjacent sections of steel pipes are connected by screw threads, two adjacent sections of steel pipes are welded annularly and then are longitudinally welded with reinforcing steel plates 6 along the steel pipe joints, the width of each reinforcing steel plate 6 is not less than 1/3 of the diameter of the pipe shed 3 (steel pipe), and the length of each reinforcing steel plate is not less than 1.5 times of the diameter of the steel pipe of the pipe shed 3. The pipe wall of the pipe shed 3 is provided with grouting holes with the longitudinal (length direction of the pipe shed 3) interval of 800mm, the grouting holes are arranged in a quincunx shape, 5 holes are arranged in a circumferential (radial) direction, and the size of each hole is 10 mm.

Specifically, the steel reinforcement cage 8 includes a round tube type steel reinforcement cage framework 81 and steel reinforcements 82 arranged on the outer side surface of the steel reinforcement cage framework 81, the steel reinforcements 82 are provided with a plurality of steel reinforcements, and all the steel reinforcements 82 are arranged on the outer side surface of the steel reinforcement cage framework 81 at equal intervals.

The steel reinforcement cage framework 81 is a steel pipe with an outer diameter of 45mm and a wall thickness of 3.0 mm. The reinforcing steel bars 82 are fixedly connected with the reinforcement cage framework 81 in a welding mode.

3. Advanced small catheter 4

The advanced small pipe 4 is matched with the pipe shed 3 for use, and the plurality of advanced small pipes 4 are positioned between the tunnel excavation contour line and the full-section deep-hole pre-grouting outer contour line and used for reinforcing rock soil close to the inner side surface of the tunnel.

The advanced small catheter 4 adopts

The wall thickness of the seamless steel pipe with the thickness of 2.5mm is 2.5m, the longitudinal (the length direction of the advanced small guide pipe 4) interval of grouting holes formed in the pipe wall is 200mm, the circumferential (radial) interval is 40mm, and the size of the hole is 8 mm. The front end of the leading small pipe 4 is tapered to facilitate plunging and prevent slurry from rushing forward. The small advanced guide pipes 4 are longitudinally arranged at intervals of 1.5 degrees obliquely upwards by taking the steel frame 2 as a fulcrum, are annularly arranged in the gaps of the pipe sheds 3, and the pipe ends exceed the outer part of the steel frame 2 by 10cm so as to be convenient for connecting grouting pipes.

18-shaped steel or grid steel frames are adopted for the steel frames 2, the distance between the steel frames 2 (the distance along the depth direction of the tunnel) is 0.5m, and reinforcing meshes are additionally arranged on the inner side and the outer side of each steel frame 2 for mesh spraying.

The utility model discloses still set up steelframe 2, steelframe 2 sets up along the tunnelling direction interval in the tunnel excavated, the one end and the steelframe 2 fixed connection of little pipe 4 in advance, has 15 to 25 contained angles (for example 15 °, 16 °, 17 °, 18 °, 19 °, 20 °, 21 °, 22 °, 23 °, 24 °, 25 °) between the axis of little pipe 4 in advance and the tunnel central line. The included angle between the axis of the leading small conduit 4 and the tunnel center line is determined according to the distance between the steel frames 2, if the distance between the steel frames 2 is 0.5m, the included angle between the leading small conduit 4 and the tunnel center line is 15-25 degrees during actual operation, so that the leading small conduit cannot reach the range of the front steel frame 2, and the erection of the steel frame 2 is not influenced.

The utility model discloses fixed to pipe shed 3 and leading little pipe 4 is realized through following mode: the utility model adopts the full-face grouting sleeve valve pipe 1 grouting mode, which can reinforce the stratum and provide a supporting fulcrum for the dense-net type pipe shed 3, wherein the supporting fulcrum refers to the soil body which is not excavated in the front and is reinforced by the full-face grouting sleeve valve pipe 1 grouting, and the soil body which is reinforced and the steel frame 2 which is excavated and erected form two fulcrums to play the role of carrying a shoulder pole; a steel frame 2 is arranged in an excavated tunnel, the end part of the advanced small guide pipe 4 is welded and fixed with the steel frame 2, and the steel frame 2 can be used as a fulcrum of the advanced small guide pipe 4.

Before actual construction, the tunnel excavation contour line and the full-section deep hole pre-grouting outer contour line of the tunnel are designed, the trend of the excavated tunnel, the structural size of the tunnel and the like are determined, tunneling is carried out according to determined data, and then the excavation section is determined, namely the area contained by the tunnel excavation contour line. The utility model discloses in carry out full section slip casting according to the excavation section, foretell full section is the cross section in tunnel (not excavation), and full section slip casting is that slip casting scope 11 covers whole tunnel section.

And adopting a grouting sleeve valve pipe 1 for grouting to reinforce the front face and surrounding rocks of the subsequent excavation, then arranging a plurality of rows of dense net type pipe sheds 3 along with the pipe to serve as supports, and supporting the surrounding rocks at the top of the excavation section through the pipe sheds 3. And leading small pipes 4 are arranged in the gaps of the pipe sheds 3, and the rock-soil strength near the inner side surface of the tunnel is reinforced through the leading small pipes 4. After the tunnel is excavated, the steel frame 2 is erected in the tunnel in time, the advanced small guide pipe 4 is erected after the steel frame 2 is erected, and the advanced small guide pipe 4 is welded with the steel frame 2. And then reinforcing meshes are additionally arranged on the inner side and the outer side of the steel frame 2, and concrete is sprayed on the meshes to form a stable supporting surface. After the construction of one tunneling section is completed, the pipe shed working chamber 5 is excavated, and then the circular construction is performed according to the above mode until the construction of the underground tunnel is completed.

For the construction, the specific requirements are as follows: 1. a grouting sleeve valve pipe 1 is longitudinally arranged in the tunnel, cement slurry is injected into the stratum through the grouting sleeve valve pipe 1, and the grouting diffusion radius of the single grouting sleeve valve pipe 1 is not less than 1 m; 2. the pipe sheds 3 are arranged at intervals of 500mm in a dense net mode, reinforcing cages 8 are placed in each pipe shed 3 after the pipe sheds 3 are arranged, cement paste is injected into each pipe shed 3, and the pipe sheds 3 and peripheral sand pebbles form an integral supporting system.

The longitudinal direction of the tunnel is the heading direction of the tunnel, or is understood to be the depth direction of the tunnel.

The leading small catheter 4 is fixed in the following way: after a tunnel (a certain section) is excavated, a steel frame 2 is arranged in the tunnel, then an advanced small guide pipe 4 is arranged, the advanced small guide pipe 4 is welded with the steel frame 2, reinforcing meshes are additionally arranged on the inner side and the outer side of the steel frame 2, and concrete is sprayed, so that the arranged advanced small guide pipe 4 and the steel frame 2 can form a shell support for supporting surrounding rocks between the lower part of a pipe shed 3 and the excavation outline.

Specifically, the section is excavated, a steel frame 2 is erected in time, then a small advanced guide pipe 4 is arranged at intervals, the section is excavated to the next pipe shed working chamber 5 in a circulating mode, and a next circulating dense-net type advanced support system is arranged according to the construction procedure of the previous excavation section.

Referring to fig. 5, in the vertical section of the excavated tunnel, the excavation range of the pipe shed working chamber 5 should cover the arrangement range of the pipe shed 3 and the advanced small ducts 4, and a primary support 12 and a secondary support 13 are arranged outside the outer contour of the pipe shed working chamber 5.

Compared with the prior art, the utility model discloses the undercut construction operation that more is applicable to the sandy gravel stratum through adding dense net formula pipe shed 3 and slip casting, has effectively utilized the self skeleton effect of sandy gravel stratum, compares the undercut engineering under the sandy gravel stratum in the past, the utility model discloses effectively controlled the stratum and subsided, restricted the emergence of the super side's of excavation condition, excavation length is not restricted in the construction simultaneously, has practiced thrift engineering cost, guarantees construction and peripheral building safety, provides the powerful guarantee for city undercut engineering safety construction.

For the convenience of description of the construction operation of the present invention, it is explained here that: in the underground excavation engineering, a tunnel body structure formed by tunneling according to a tunnel excavation contour line is taken as a tunnel; during tunneling, a tunneling surface in the tunnel is a tunnel face; the working surface formed by combining the area around the tunnel excavation contour line and the tunnel face is an excavation section. The section of the pipe shed working room 5 is larger than the tunnel face of a common section, so that a larger operation space (the pipe shed working room 5) can be provided, and construction operation is facilitated.

The utility model provides a close-mesh advance support system in undercut tunnel for the support of wearing the engineering under the undercut, the undercut engineering under the specially adapted sand cobble stratum. In this supporting system, the utility model discloses can be through the mode of slip casting, effectively stabilize excavation face the place ahead face, can provide effective support for pipe shed 3 simultaneously. The utility model discloses a beat and establish close net formula pipe canopy 3 and provide support chassis and slip casting for the stratum, can utilize country rock self stability better. After the pipe shed 3 is arranged, surrounding rocks below the pipe shed 3 and among the sheds can be stabilized by arranging the advanced small guide pipes 4, and overexcavation is reduced, so that a set of advanced support system is formed. The utility model discloses construction technical scheme has practiced thrift engineering cost more in the past, safe and reliable more.

The utility model discloses used a close-mesh advance support construction method in undercut tunnel, be applied to the undercut engineering, the undercut engineering in specially adapted sand cobble stratum is through this construction method the utility model discloses can establish one set of close-mesh advance support system to a reliable undercut is strutted.

The construction method of the dense-mesh type advance support mainly comprises the following construction steps: step one, constructing a grout stop wall; secondly, grouting and reinforcing the excavated area; step three, arranging a pipe shed 3; and step four, arranging a small advanced guide pipe 4 in the gap of the pipe shed 3.

Specifically, in step two: and (3) driving a grouting sleeve valve pipe 1 according to the outline of the excavated section, and performing full-section grouting reinforcement on the excavated section through grouting of the grouting sleeve valve pipe 1.

The grouting sleeve valve pipe 1 is a grouting tool, can well control the grouting range 11 and the grouting pressure, can perform repeated grouting, and has low possibility of causing grout leakage and grout string. The full-section grouting sleeve valve pipe 1 is arranged according to the contour of the excavated section, namely the grouting sleeve valve pipes 1 for grouting are uniformly arranged in the tunnel face, the grouting sleeve valve pipes 1 are obliquely arranged relative to the center line of the tunnel, and the center line of the tunnel, namely the connecting line of the circle centers of the arc arches of the tunnel, is parallel to the tunneling direction of the tunnel, so that grouting can be performed in the tunnel (not excavated) and the surrounding area of the tunnel, and the reinforcement of the tunnel face and the surrounding area of the tunnel face is achieved. And grouting in advance, so that the stratum can be reinforced to stably excavate the tunnel face. Meanwhile, the surrounding area of the tunnel face is reinforced, so that the surrounding geotechnical structures of the tunnel face can provide a front stable fulcrum of the dense-net type pipe shed 3 in the subsequent engineering.

In the construction method of the dense-net type advanced support of the underground excavation tunnel, a pipe shed support is arranged in the third step.

Specifically, in step three: pipe shed 3 sets up in the upper portion of tunnel excavation contour line, the upper portion of tunnel vault circular arc promptly, and pipe shed 3 lays according to the shape of tunnel vault circular arc upper portion on it, and pipe shed 3 is provided with two rows at least, and each calandria canopy 3 is outwards range upon range of setting from tunnel vault circular arc.

In general, the arc of the vault of the tunnel is a smooth arc-shaped curve, then, according to the tunnel excavation contour line, a row of pipe sheds 3 arranged at equal intervals are arranged on the upper portion of the tunnel excavation contour line and at a certain distance away from the tunnel excavation contour line along a smooth curve (virtual), then, a second pipe shed 3 is arranged in the outer area of the first pipe shed 3, and according to the stratum structure and the design requirements, multiple layers (including two layers) of pipe sheds 3 can be arranged for excavation, reinforcement and support.

It should be noted that: in the same calandria shed 3, the vertical distance from the calandria shed 3 to the tunnel excavation contour line is the same.

In the third step, the aim is to arrange a dense net type pipe shed support. The utility model discloses in the pipe shed strut that founds, each calandria canopy 3 is crossed from top to bottom and is arranged and form close net structure system, in two adjacent rows of pipe sheds 3 promptly, outer pipe shed 3 is located the intermediate position of two adjacent pipe sheds 3 of inlayer.

Two rows of dense-net type pipe sheds 3 are supported and arranged on the arch crown of the tunnel, the two rows of pipe sheds 3 are arranged in a staggered mode to form a net shape, and pipe shed grout overflow holes are formed in the pipe wall of each pipe shed 3 in a quincunx mode. In same one row of pipe shed 3, the 3 hoop intervals of two adjacent pipe sheds are the optimum and are 0.5m, certainly, can suitably reduce 3 hoop intervals of pipe shed or increase 3 hoop intervals of pipe shed according to ground characteristics.

Pipe shed 3 is provided with a pipe shed grout overflow hole, and a drill bit 7 is arranged at the end part of pipe shed 3, so that pipe shed 3 can be driven conveniently. After pipe shed 3 is squeezed into the stratum, set up steel reinforcement cage 8 in pipe shed 3, then to pipe shed 3 slip casting, the thick liquid of part slip casting overflows and links into an entirety with the stratum between pipe shed 3 and pipe shed 3 through 3 wall grout holes of pipe shed, and pipe shed 3 sets up and can regard as stratum structure skeleton in the stratum.

The specific layout of the pipe shed 3 includes the following two types: 1. one end of the pipe shed 3 is fixed, the lifting angle of the other end of the pipe shed 3 relative to the horizontal plane is consistent, and an included angle of 1-3 degrees is formed between the pipe shed 3 and the central line of the tunnel; 2. one end of the pipe shed 3 is fixed, the other end of the pipe shed 3 is consistent in lifting angle relative to the tangent plane of the tunnel roof arc, and an included angle of 1-3 degrees is formed between the pipe shed 3 and the center line of the tunnel.

Before the operation is carried out, a first step of constructing a slurry stopping wall, wherein the slurry stopping wall is used for preventing overflow and slurry overflow. The utility model discloses well 1 slip casting of full section slip casting sleeve valve pipe need be executed at the undercut tunnel face and make 300mm-500mm thick plain concrete grout stopping wall, and the supporting structure of follow-up pipe shed 3's guide wall and pipe shed 3 can also be regarded as to the grout stopping wall.

Embedding in the grout stop wall according to the arrangement mode of the grouting sleeve valve pipe 1

The seamless steel tube is used as an orifice tube, and the length of the orifice tube is 1.5 m. Grouting sleeve valve pipe 1 adopts

The rigid PVC pipe is required to bear the maximum pressure of more than 3.0MPa, grouting pipe grouting holes are formed in the pipe wall of the grouting sleeve valve pipe 1, the opening intervals of the grouting pipe grouting holes are arranged according to a 300mm quincunx shape, a rubber sleeve is tightly hooped outside the opening, and the grouting pipe grouting holes are covered by the rubber sleeve. The bottom end of the grouting sleeve valve pipe 1 is tightly wrapped by geotextile and other objectsAnd (4) the sleeve is tightly pricked, so that sleeve materials are prevented from entering the grouting sleeve valve pipe 1.

During grouting and reinforcing, pure cement slurry (cement slurry-water glass double-liquid slurry is adopted when precipitation is difficult) is adopted. Namely: and during grouting reinforcement, cement slurry is adopted for grouting, the water-cement ratio in the cement slurry is 0.8:1, a composite water-reducing early strength agent with the cement dosage of 0.3-0.5% can be added into the cement slurry, and the grouting pressure is 1.0-1.5 MPa.

In the second step: the grout for grouting reinforcement has a diffusion radius of not less than 1.0m, and the diffusion ranges of the farthest grouting sleeve valve pipes 1 for grouting reinforcement are not less than 0.2m through mutual engagement. Namely: the grout diffusion radius is not less than 1.0m, the driving angle and the position of the grouting sleeve valve pipe 1 are adjusted according to the section and the operation space, and the grouting diffusion ranges of the grouting sleeve valve pipes 1 at the farthest position are guaranteed to be mutually occluded by not less than 0.2 m.

In step four, a leading small pipe 4 is arranged in the gap of the pipe shed 3.

Further, in order to consolidate the tunnel and support leading little pipe 4, the utility model discloses in, vertically set up steelframe 2 along the sectional length direction interval in excavation, steelframe 2 sets up along the tunnel. Wherein, the one end and the steelframe 2 fixed connection of little pipe 4 in advance, along the excavation tunnelling direction, the other end of little pipe 4 in advance keeps away from the tunnel central line, has the contained angle of 15 ~ 25 between the axis of little pipe 4 in advance and the tunnel central line.

The small ducts are arranged at intervals in front of the small ducts along the arrangement direction of the steel frames 2. The arrangement of the advanced small conduit 4 at intervals specifically comprises the following steps: the advanced small guide pipe 4 is connected with a steel frame 2 (assumed as a first steel frame), and the next advanced small guide pipe 4 is connected with the next steel frame 2 (assumed as a third steel frame) after passing through a steel frame (assumed as a second steel frame) along the depth direction of the tunnel.

To the tunnel that excavates, the utility model discloses set up the steelframe in the tunnel for to realizing the support of strutting in tunnel initial stage. After the tunnel is excavated, concrete is sprayed firstly, the thickness of the concrete is about 35mm, then the net is hung, a steel frame is erected, the operation of erecting the steel frame comprises the steps of arranging the steel frame, arranging longitudinal connecting ribs, anchor rods and the like, and immediately, the concrete is continuously sprayed to the designed thickness after the steel frame is erected.

During excavation and tunneling, a steel frame 2 is arranged in a dug tunnel, the tunnel is reinforced by the steel frame 2, and meanwhile, a 2.5 m-long advanced small guide pipe 4 is arranged between pipe sheds 3 by taking the steel frame 2 as a fulcrum. The leading small conduit 4 is arranged in the pipe shed 3 at an angle of 1.5 degrees, and the pipe wall is provided with grouting holes according to a quincunx shape for grouting.

Specifically, in step three: when the pipe shed 3 is arranged, the pipe shed 3 is constructed by adopting pipe jacking, the pipe shed 3 is subjected to grouting, cement paste is adopted for grouting when the pipe shed 3 is grouted, the ratio of water to cement to sand in the cement paste is 0.8:1, the grouting pressure is 1.0MPa, and air is exhausted in a pipe to ensure compact filling.

In step four: after the leading small guide pipe 4 is arranged, grouting is carried out on the leading small guide pipe 4, cement-water glass double-liquid slurry is adopted when the leading small guide pipe 4 is grouted, the ratio of the slurry is W to C which is 1 to 1, the ratio of C to S which is 1 to 1 (volume ratio), and the grouting pressure is 0.5-1.0 MPa. Wherein W is water, C is cement, and S is water glass.

When grouting reinforcement is carried out, cement slurry is adopted, the water cement ratio is 0.8:1, a composite water reducing early strength agent with the cement dosage of 0.3% -0.5% can be added into the slurry, the grouting pressure is 1.0 MPa-1.5 MPa, the single-hole grouting pressure reaches the design final pressure and grouting is continued for more than ten minutes or the single-hole grouting amount is approximately the same as the design grouting amount, and the hole grouting can be finished.

In the dense-net type pipe shed 3 support, the pipe shed 3 is constructed by jacking with a pipe, a reinforcement cage 8 is placed after the construction is finished, and the reinforcement cage 8 is formed by one reinforcement cage

4 steel pipes with the wall thickness of 3.0mm are welded on the periphery of the framework

And (3) forming reinforcing steel bars, and then pouring cement paste by adopting a retreating process, namely inserting the grouting sleeve valve pipe 1 to the farthest end of the pipe shed 3, and then grouting while retreating the pipe, so that the filling flow of the pipe can be compact. The ratio of water to cement to sand is 0.8:1, the grouting pressure is 1.0MPa, and the air is exhausted from the pipe to ensure the compact filling.

The advanced small conduit 4 adopts cement-water glass double-liquid slurry for grouting, the ratio of the slurry is W to C is 1 to 1, the ratio of C to S is 1 to 1 (volume ratio), and the grouting pressure is 0.5 MPa-1.0 MPa.

Please refer to fig. 9 to fig. 11. The utility model discloses in actual work progress, reinforced grouting scope 11 of slip casting should not influence existing building, perhaps the outermost edge of grouting scope 11 just contacts with the foundation structure or the pile foundation structure of existing building (the contact that just contacts here indicates the sub-range), like this can reach reinforced (rfd) the while, still can not influence existing building.

For example, in fig. 9, when the tunnel passes through the building a with five stories, the grouting range 11 is designed according to the construction range of the foundation of the building a with five stories, so that the grouting range 11 is positioned below the foundation of the building a with five stories, and the outermost edge of the grouting range 11 is just contacted with the outermost layer of the foundation.

For example, in fig. 10, when a tunnel passes through the bridge, the bridge is a viaduct, the bridge body is supported by the bridge pile foundations b, the bridge pile foundations b have a certain depth of penetration, the grouting range 11 is designed according to the arrangement mode of the bridge device b on the ground surface and the depth of penetration, and it is ensured that when the tunnel passes through the bridge, the grouting range 11 can cover all the bridge pile foundations b above the tunnel, and the outermost edge of the grouting range 11 just contacts with the lower portion of the bridge pile foundations b.

For example, in fig. 11, when the tunnel passes through the flood discharge channel c, the bottom of the flood discharge channel c is a concrete foundation, and the grouting range 11 is completely below the concrete foundation and does not contact with the concrete foundation.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A dense-net type advanced support system of an underground excavation tunnel is characterized in that,

a tunnel excavation contour line and a full-section deep-hole pre-grouting outer contour line are designed on the excavation section of the tunnel, and the tunnel excavation contour line is positioned in the full-section deep-hole pre-grouting outer contour line;

the support system includes:

one end of each grouting sleeve valve pipe is positioned on an excavation section, the other end of each grouting sleeve valve pipe extends towards the tunneling direction of the tunnel, and one end of each grouting sleeve valve pipe is distributed in the tunnel excavation contour line;

and the pipe sheds are positioned between the tunnel excavation contour lines and the full-section deep-hole pre-grouting outer contour lines and form a dense-net type pipe shed.

2. The dense-mesh type advanced support system of the underground excavated tunnel according to claim 1, further comprising:

the advanced small guide pipes are located between the tunnel excavation contour lines and the full-section deep-hole pre-grouting outer contour lines and used for reinforcing rock and soil close to the inner side face of the tunnel.

3. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 1,

a plurality of pipe sheds are arranged on the periphery of the arc of the tunnel arch part to form a single-row pipe shed;

in the single-row pipe sheds, the distances from the pipe sheds to the arc of the arch part of the tunnel are the same;

the single-row pipe shed is provided with at least two groups, the distance from the pipe shed to the arc of the tunnel arch in each single-row pipe shed is different, and the pipe sheds in the two adjacent groups of single-row pipe sheds are arranged in a staggered mode.

4. The dense-mesh type advanced support system of the underground excavated tunnel according to claim 1, further comprising a grout stop wall provided at a start end of each excavation section.

5. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 4,

one end of the pipe shed is fixedly connected with the grout stopping wall, and an included angle of 1-3 degrees is formed between the axis of the pipe shed and the center line of the tunnel.

6. The dense-mesh type advanced support system of the underground excavated tunnel according to claim 2, further comprising steel frames which are arranged at intervals in the excavated tunnel in the tunneling direction of the tunnel.

7. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 6,

one end of the advanced small guide pipe is positioned on an excavation section and takes the steel frame as a fulcrum, and an included angle of 15-25 degrees is formed between the axis of the advanced small guide pipe and the central line of the tunnel.

8. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 2,

a reinforcement cage is arranged in the pipe shed, pipe shed grout overflow holes are formed in the pipe shed, the pipe shed grout overflow holes are uniformly distributed in the pipe shed, small guide pipe grout overflow holes are formed in the advanced small guide pipes, and the small guide pipe grout overflow holes are uniformly distributed in the advanced small guide pipes.

9. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 8,

the steel reinforcement cage is in including tubular steel reinforcement cage skeleton and setting the reinforcing bar on the lateral surface of steel reinforcement cage skeleton, the reinforcing bar is provided with many, all the reinforcing bar in equidistant setting on the lateral surface of steel reinforcement cage skeleton.

10. The dense-mesh type advance support system of an underground excavated tunnel according to claim 4 or 5,

one end of the grouting sleeve valve pipe is located on the grout stopping wall, the grouting sleeve valve pipe is arranged around the center line of the tunnel at intervals, one end of the grouting sleeve valve pipe is fixed, and the other end of the grouting sleeve valve pipe is divergently arranged relative to the center line of the tunnel.

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