A rapid roof-lifting construction method for soft rock tunnels

Abstract

The application discloses a soft rock tunnel rapid roof picking construction method, relates to the technical field of tunnel construction, and comprises the following steps: construction preparation, advanced geological prediction, measurement and line drawing, hole body excavation, initial support, erection of a reinforced steel frame and roof picking construction. The method has the advantages of high construction efficiency, small disturbance to surrounding rock, good construction quality and the like, is suitable for the construction of tunnels with various soft rock geological conditions, certain section sizes and length ranges, and provides an efficient, safe and stable solution for the rapid roof picking construction of soft rock tunnels.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a rapid roof-lifting construction method for soft rock tunnels. Background Technology

[0002] In tunnel construction, it is common to encounter situations where tunnel cross-section expansion, or roof-opening operations, are necessary due to different construction stages or design changes. Soft rock tunnels, with their low rock strength, well-developed joints and fissures, and poor self-stabilizing ability, present numerous challenges for roof-opening operations. Traditional roof-opening methods for soft rock tunnels often suffer from low construction efficiency, high safety risks, and significant disturbance to the surrounding rock. For example, some conventional methods can easily trigger surrounding rock collapses when breaking down the original support structure and excavating the upper rock mass, thus affecting construction progress and endangering the safety of construction personnel. Furthermore, due to the characteristics of soft rock, the installation of the support structure after excavation and the control of surrounding rock deformation are difficult to coordinate effectively, leading to extended construction periods. Therefore, developing a rapid roof-opening technology suitable for soft rock tunnels is of significant practical importance. Summary of the Invention

[0003] The purpose of this invention is to provide a rapid roof-lifting construction method for soft rock tunnels in order to solve the above-mentioned problems. This method has the advantages of high construction efficiency, minimal disturbance to the surrounding rock, and good construction quality. It is applicable to tunnel construction under various soft rock geological conditions and within a certain range of cross-sectional dimensions and lengths.

[0004] The present invention achieves the above objectives through the following technical solutions:

[0005] A rapid roof-lifting construction method for soft rock tunnels includes the following steps:

[0006] (1) Construction preparation: Carry out technical preparation work, conduct technical briefing and safety technical briefing training for the workers; prepare and inspect the required materials, including advanced small guide pipes, steel frames, anchor bolts, steel mesh and concrete, etc.

[0007] (2) Advanced geological forecasting: Geological sketching, elastic wave reflection method (TSP), and electromagnetic wave reflection method (geological radar) are used to forecast the geological conditions ahead, and the forecast results guide the excavation and support measures of the tunnel face of the top section.

[0008] (3) Measurement and marking: Determine the tunnel excavation outline according to the design drawings, and mark the tunnel centerline, arch center position, excavation outline, bottom plate elevation, etc. on the excavation face;

[0009] (4) Excavation of the tunnel body: The micro-step method is adopted for construction. The advance per cycle is no more than 1.0m. The advance of the upper step is no more than the spacing of 1 steel frame, and the advance of the lower step is no more than the spacing of 2 steel frames. The anchor pipe is installed before the excavation of the invert arch. The advance of the invert arch is no more than the spacing of 3 steel frames per cycle. During the excavation process, the transition section at the intersection of the transverse tunnel and the main tunnel is excavated first, and then the excavation is gradually expanded to the main tunnel to form a working face.

[0010] (5) Initial support: After the excavation is completed, the initial support of the tunnel structure is carried out, including initial shotcrete, shotcrete and anchor mesh system support, erection of the tunnel structure steel frame, installation of anchor bolts and re-shotcrete to the design thickness.

[0011] (6) Erecting a reinforcing steel frame: Erect a reinforcing steel frame at the intersection of the transverse tunnel and the main tunnel, and erect the main tunnel steel frame. Remove the temporary support to form a working surface;

[0012] (7) Overhead construction: Following the above steps, complete the overhead construction of the left and right lines of the main tunnel, including the excavation and support of the upper and lower steps, until the overhead construction is completed.

[0013] Preferably, the length of the micro-step excavation step is controlled within 3 to 5 meters, the initial support is promptly closed into a ring after tunnel excavation, and the distance between the initial support of the invert arch and the foremost face is not greater than 35 meters.

[0014] Preferably, in the construction preparation steps, 20 meters before entering the main tunnel and lifting the roof, the advanced geological forecast data is analyzed, and the active support parameters of the roof lifting, the advanced reinforcement measures, the auxiliary tunnels and the initial support reinforcement sections of the active intersections are dynamically confirmed.

[0015] Preferably, during the excavation process, the excavation is gradually widened to an uphill slope, with simultaneous excavation and support. The excavation section and the cross-section of the transverse tunnel form an upper step section with a height of 5.2m to 7.5m.

[0016] Preferably, in the initial support step, the initial shotcrete thickness is 4cm, and the shotcrete is then sprayed to the designed thickness.

[0017] Preferably, the reinforcing steel frame adopts a double-layer reinforcing ring steel frame, and the main hole steel frame is connected to the reinforcing ring steel frame at the intersection by welding.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The rapid roof-lifting construction method for soft rock tunnels of the present invention effectively improves construction efficiency, reduces safety risks, and reduces disturbance to the surrounding rock through measures such as micro-step construction, enhanced geological forecasting, accurate measurement and marking, strict control of excavation progress, and timely closure of initial support. It provides an efficient, safe, and stable solution for rapid roof-lifting construction of soft rock tunnels. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the construction process described in this invention.

[0021] Figure 2 This is a plan view and a schematic diagram of the steel frame of the transition section from the transverse tunnel to the main tunnel as described in this invention.

[0022] Figure 3 This is a schematic diagram of the stepped gradual expansion excavation on the left side of the horizontal 4-entry main tunnel as described in this invention.

[0023] Figure 4 This is a schematic diagram of the steel frame erection for the right line of the main tunnel as described in this invention.

[0024] Figure 5 This is a schematic diagram of the steel frame erection for the left line of the main tunnel as described in this invention.

[0025] Figure 6 This is a schematic diagram of the gradual expansion excavation of the transverse tunnel into the main tunnel as described in this invention.

[0026] Figure 7 This is a schematic diagram of the gradual expansion excavation of the left line of the horizontal 4-advance main tunnel as described in this invention. Detailed Implementation

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] The present invention will be further described below with reference to the accompanying drawings:

[0029] Example 1

[0030] like Figures 1-7 As shown, a rapid roof-lifting construction method for soft rock tunnels includes...

[0031] 1. Construction preparation:

[0032] (1) When entering the main tunnel 20 meters before the top is lifted, notify the Luolong Project Department to organize all parties to conduct a site survey, analyze the advanced geological forecast data, and dynamically confirm the active support parameters, advanced reinforcement measures, auxiliary tunnels and the initial support reinforcement section of the active intersection.

[0033] (2) When the distance between the auxiliary tunnel and the main tunnel is less than 10m and after the main tunnel is opened, the principle of "pre-reinforcement before excavation and support for each section of Class IV and V soft surrounding rock and unfavorable geological conditions shall be strictly followed. Each cycle of excavation shall not exceed 1 section.

[0034] (3) After the reinforcement support measures within 3 to 5 meters of the main tunnel are completed, the Luolong Project Department shall organize the acceptance of the conditions for the roof opening construction in accordance with the tunnel entry acceptance procedure. Only after the conditions are passed can the roof opening construction begin.

[0035] 2. Specific construction steps:

[0036] (1) When the normal excavation and support construction of the No. 5 cross tunnel reaches the transition section, the transition section is reinforced with support, 10 I18 steel frames are erected for support, and a closed ring steel frame is added in the bottom plate.

[0037] (2) When the last steel frame of the transverse tunnel is installed, the temporary support of the right-line main tunnel is constructed by gradually climbing upwards and expanding the excavation. After the construction reaches the arch of the main tunnel, the temporary support of the right-line main tunnel is gradually lowered and construction continues until the construction of the transverse tunnel is completed and one steel frame is installed, forming an upper step operating platform. Each steel frame is raised (lowered) by 41cm. The micro-step method is used for excavation, with an advance of 1.0m per cycle. The excavation elevation is 25cm outside the excavation outline of the main tunnel (excluding the reserved deformation amount) to facilitate the initial support steel frame erection at the intersection of the main tunnel. Considering that the deformation of the surrounding rock may be large, the actual excavation size is raised by 10-12cm higher than the designed arch elevation. During construction, the excavation is gradually expanded into an uphill excavation, and support is carried out while excavating. The excavation section forms an upper step section with the transverse tunnel section, and the height of the upper step is 5.2m-7.5m.

[0038] (3) After all the temporary support for the upper step of the right tunnel is completed, the temporary support for the lower step of the right tunnel will be constructed. The left and right sides will be staggered. The excavation advance shall not exceed the distance between two steel frames. After excavating to the horizontal 4th step, the excavation will be carried out in parallel with the upper step of the horizontal 4th step.

[0039] (4) After the construction of the lower step of the right tunnel is completed and a micro step is formed with the excavation and support of the upper step of the horizontal tunnel 4, the temporary support of the lower step of the right tunnel and the upper step of the horizontal tunnel 4 are carried out simultaneously until the normal construction of the horizontal tunnel 4 begins. The cross-section adopts the cross-section of the temporary support. The initial support steel frame adopts I18 steel frame, the transition section spacing is 0.8m, and the normal section spacing is 1m. The step height is 5.7m for the upper step and 2m for the lower step.

[0040] (5) When constructing the last steel frame of the horizontal 4th section, the temporary support of the upper step of the left line main tunnel is gradually raised and expanded upward. After the construction reaches the arch of the main tunnel, the temporary support of the left line main tunnel is gradually lowered and construction continues to the left line side wall. Each steel frame is raised (lowered) by 41cm; the micro-step method is used for excavation, and the advance is 1.0m per cycle.

[0041] (6) After the temporary support of the upper step of the left main tunnel is completed, the temporary support of the lower step of the left main tunnel will be constructed. The left and right sides will be staggered and the excavation advance shall not exceed the spacing of 2 steel frames; the height of the lower step is 2.5m.

[0042] (7) After the excavation and support of the lower step of the main tunnel is completed, erect the double reinforced ring steel frame at the intersection of the horizontal 4 and the left line of the main tunnel, and erect the main tunnel arch frame. The main tunnel steel frame is connected to the reinforced ring steel frame at the intersection of the horizontal 4 and the left line by welding, and the other end is directly lowered to the bottom. After the erection is completed, spray the initial support concrete of the main tunnel in time.

[0043] (8) Remove the temporary support steel frames on both sides of the left line of the main tunnel, and excavate and support the upper steps at different distances from the left and right mileages. After the upper steps on both sides are excavated to a length of 10 meters, close the working face and carry out the lower step excavation and support. After forming a micro step, proceed with the normal excavation and construction process. The left line cantilever is completed.

[0044] (9) After the left line is completed, erect reinforcing ring steel frames at the intersection of the 4th and right lines and the intersection of the 5th and right lines respectively, and then construct the initial support steel frame of the right line main tunnel at the intersection; the main tunnel steel frame is connected to the reinforcing ring steel frame at the intersection by welding; after the steel frame is constructed, spray the initial support concrete of the main tunnel in time.

[0045] (10) Remove the temporary support steel frames on both sides of the right line of the main tunnel at different mileages, and excavate and support the upper steps at different mileages. After the upper steps on both sides are excavated to a length of 10 meters, close the working face and carry out the lower step excavation and support. After forming a micro step, proceed with the normal excavation and construction process. The right line cantilever is completed.

[0046] Through the above specific implementation methods, the rapid roof-lifting technology for soft rock tunnels of the present invention can efficiently and safely complete the roof-lifting construction task under soft rock geological conditions, effectively solving the problems of low construction efficiency, high safety risks, and large disturbance to the surrounding rock that exist in traditional roof-lifting methods. It has significant economic and social benefits and provides a reliable technical solution for soft rock tunnel engineering construction.

[0047] Example 2

[0048] A rapid roof-lifting construction method for soft rock tunnels includes the following steps:

[0049] (1) When the normal excavation and support construction of the No. 5 cross tunnel reaches the transition section, the transition section is reinforced with support, 10 I18 steel frames are erected for support, and a closed ring steel frame is added in the bottom plate.

[0050] (2) At the last steel frame of the transverse tunnel, gradually climb up and excavate upward to expand the temporary support of the right line main tunnel until the arch of the main tunnel is reached. Then gradually lower and continue to construct the temporary support of the right line main tunnel until the 4th steel frame is installed to form an upper step operating platform.

[0051] (3) After all the temporary support for the upper step of the right tunnel is completed, the temporary support for the lower step of the right tunnel will be constructed, with the left and right sides working separately.

[0052] (4) After the construction of the lower step of the right tunnel is completed and a micro step is formed with the excavation and support of the upper step of the horizontal tunnel 4, the temporary support of the lower step of the right tunnel and the upper step of the horizontal tunnel 4 are carried out simultaneously.

[0053] (5) At the last steel frame of Shiheng 4, gradually climb up and excavate the upper step of the left line main tunnel to build temporary support until the arch of the main tunnel is reached. Then gradually lower and continue to build the temporary support of the left line main tunnel to the left line side wall.

[0054] (6) After all the temporary support for the upper step of the left main tunnel is completed, the temporary support for the lower step of the left main tunnel will be constructed, with the left and right sides working separately.

[0055] (7) After the excavation and support of the lower step of the main tunnel is completed, erect the double reinforced ring steel frame at the intersection of the horizontal 4 and the left line of the main tunnel, and erect the main tunnel arch frame. The main tunnel steel frame is connected to the reinforced ring steel frame at the intersection of the horizontal 4 and the left line by welding.

[0056] (8) Remove the temporary support steel frame on both sides of the left line of the main tunnel and the upper step of the support. After the upper step on both sides is excavated to a length of 10 meters, the working face is closed and the lower step is excavated and supported. After forming a micro step, the normal excavation process is started.

[0057] (9) After the left line is completed, erect reinforcing ring steel frames at the intersection of the 4th and right lines and the intersection of the 5th horizontal tunnel and the right line respectively. Then construct the initial support steel frame of the right line main tunnel at the intersection. The main tunnel steel frame is connected to the reinforcing ring steel frame at the intersection by welding.

[0058] (10) Remove the temporary support steel frames on both sides of the right line of the main tunnel and the upper steps of the support. After the upper steps on both sides are excavated to a length of 10 meters, the working face is closed and the lower steps are excavated and supported. After forming micro steps, the normal excavation process is started.

[0059] Example 3

[0060] A rapid roof-lifting construction method for soft rock tunnels includes the following steps:

[0061] (1) When entering the main tunnel 20 meters before the roof is lifted, organize all parties to conduct on-site surveys, analyze advanced geological forecast data, and dynamically confirm the active support parameters, advanced reinforcement measures, auxiliary tunnels and the initial support reinforcement sections of active intersections.

[0062] (2) When the distance between the auxiliary tunnel and the main tunnel is less than 10m and after the main tunnel is opened, the principle of "pre-reinforcement before excavation, and one support for each tunnel" shall be strictly followed.

[0063] (3) After the reinforcement support measures within 3 to 5 meters of the main tunnel are completed, the acceptance of the roof construction conditions shall be carried out in accordance with the tunnel entry acceptance procedure;

[0064] (4) Carry out the construction according to steps (2) to (10) in Example 2.

[0065] In step (2), the excavation interval for each cycle shall not exceed the spacing of one steel frame to ensure construction safety and stability.

[0066] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the present invention, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A soft rock tunnel rapid roof picking construction method, characterized in that, The method comprises the following steps: (1) construction preparation: technical preparation work is carried out, and technical disclosure and safety technical disclosure training are carried out on operating personnel; required materials are prepared and inspected, including advanced small catheter, steel frame, anchor rod, steel mesh and concrete; (2) advanced geological prediction: the comprehensive method of geological sketch, elastic wave reflection method TSP and electromagnetic wave reflection method is used to predict the geological conditions in front, and the excavation support measures of the top picking section of the working face are guided according to the prediction results; (3) measurement and line drawing: the tunnel excavation contour line is determined according to the design drawing, and the tunnel center line, arch center position, excavation contour line and floor elevation are marked on the excavation working face; (4) hole body excavation: the micro-bench method is used for construction, the upper bench excavation progress is not greater than 1.0m, the upper bench excavation progress is not greater than the interval of 1 steel frame, the lower bench excavation progress is not greater than the interval of 2 steel frames, the locking anchor pipe is completed before the excavation of the inverted arch, and the inverted arch excavation progress is not greater than the interval of 3 steel frames every cycle; During the excavation process, the transition section at the intersection of the transverse hole and the main hole is excavated first, and then gradually expanded to the main hole to form the working face; (5) primary support: after the excavation is completed, the hole body structure primary support is constructed, including initial spraying of concrete, spraying of anchor net system support, erection of hole body structure steel frame, locking anchor rod and re-spraying of concrete to the design thickness; (6) erecting reinforced steel frame: reinforced steel frames are erected at the intersection of the transverse hole and the main hole, and the main hole steel frame is erected, the temporary support is removed, and the working face is formed; (7) top picking construction: according to the above steps, the top picking construction of the left line and the right line of the main hole is completed respectively, including the excavation and support of the upper bench and the lower bench, until the top picking is completed; Wherein, the micro-bench method controls the bench length to be 3-5m, the primary support is closed in time after the tunnel excavation, and the distance of the inverted arch primary support from the front working face should not be greater than 35m; In the construction preparation step, when entering the 20m of the main hole top picking, the advanced geological prediction data is analyzed, the top picking active support parameters, advanced reinforcement measures, auxiliary tunnel and initial support reinforcement section at the intersection of the transverse hole and the main hole are dynamically confirmed; In the primary support step, the initial spraying of concrete is 4cm thick, and the re-spraying of concrete is to the design thickness; The reinforced steel frame adopts double-spliced reinforced ring steel frame, and the main hole steel frame is connected with the reinforced ring steel frame at the intersection of the transverse hole and the main hole through welding.

2. The soft rock tunnel rapid roof picking construction method according to claim 1, characterized in that, During the hole body excavation process, the gradual expansion is excavated into an upward slope, and the excavation section and the transverse hole section form an upper bench section, and the upper bench height is 5.2m-7.5m.

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