A mountain V-grade surrounding rock small clear distance bias tunnel advance support and construction method

Abstract

The present application relates to the technical field of tunnel construction, in particular to a mountain V-grade surrounding rock small-clearance bias tunnel advanced support and construction method, comprising: initial support steel frame, advanced small catheter is obliquely inserted into surrounding rock, one end of the advanced small catheter is provided with a valve, a plurality of slurry outlet holes are arranged on the surface of the advanced small catheter in the shape of a plum blossom; the outer side of the regulating valve is communicated with two soft branch pipes, the valve core is provided in the shape of a cylinder with one end open, and the surface is provided with a regulating port corresponding to one soft branch pipe; the beneficial effects are that: by connecting the regulating valve with the grouting pipe end, the soft branch pipes are communicated on both sides of the regulating valve, the valve core is rotatably installed in the regulating valve, one end of the valve core is open and communicated with the grouting pipe, the regulating port is communicated with the other soft branch pipe by rotating the valve core, and the next advanced small catheter can be grouted, so that the multiple advanced small catheters can be grouted one by one in a continuous manner, and the grouting efficiency and speed are higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel construction, in particular to a mountain V-grade surrounding rock small clear distance bias tunnel advanced support and construction method. BACKGROUND

[0002] The mountain V-grade surrounding rock small clear distance bias tunnel adopts the annular excavation reserved core soil excavation method construction, according to the engineering hydrogeological conditions, the advanced support is needed according to the design requirements, prevents the surrounding rock relaxation, ensures the safety of tunnel excavation.

[0003] In the prior art, the advanced support adopts small pipe grouting, and a line spray C25 concrete is arranged along the small pipe to form a grout stop disc, the grouting is from bottom to top, and the two sides are synchronous.

[0004] However, at present, the number of small pipes for advanced support is large, and during the grouting process, after the grouting of a small pipe is completed, the grouting pipe needs to be disassembled and connected to the next small pipe, which causes the grouting process to be interrupted, the efficiency and speed of the advanced grouting are low, and the construction period is affected. Therefore, the present application provides a mountain V-grade surrounding rock small clear distance bias tunnel advanced support and construction method to solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide a mountain V-grade surrounding rock small clear distance bias tunnel advanced support and construction method to solve the problem of low efficiency of small pipe grouting of the advanced support in the background art.

[0006] To achieve the above purpose, the present application provides the following technical scheme: a mountain V-grade surrounding rock small clear distance bias tunnel advanced support, comprising:

[0007] The initial support steel frame is provided with a plurality of advanced small pipes arranged in a ring array on the side surface, the advanced small pipes are inclined and inserted into the surrounding rock, one end of the advanced small pipe is provided with a valve, and a plurality of grout outlets arranged in a plum blossom shape are formed on the surface of the advanced small pipe.

[0008] The grouting pipe is provided with an adjusting valve at one end, the outer side of the adjusting valve is connected with two soft branch pipes, and one end of the two soft branch pipes is connected with the two advanced small pipes respectively, the adjusting valve is in the form of a hollow cylinder, and a valve core matched with the adjusting valve is rotatably installed in the adjusting valve, the valve core is in the form of a cylinder with an open end, and an adjusting opening corresponding to one soft branch pipe is formed on the surface of the valve core, and a sealing pad is arranged between the surface of the valve core and the inner wall of the adjusting valve.

[0009] Preferably, both sides of the adjusting valve surface are fixedly connected with pulp outlets, two soft branch pipes are communicated with the two pulp outlets respectively, the opening end of the adjusting valve is fixed with a sealing cover plate through bolts, an arc-shaped limiting block is fixedly arranged on the surface of the sealing cover plate, one end of the valve core is fixedly connected with a connecting shaft which penetrates through the sealing cover plate, an adjusting knob is fixedly arranged on one end of the connecting shaft, and a pointing block is fixedly arranged on the surface of the connecting shaft, the pointing block is aligned with the adjusting port and is attached to one end surface of the limiting block.

[0010] A construction method of the advanced support of the mountain V-grade surrounding rock small-spacing bias tunnel according to the above, specifically comprising the following steps:

[0011] Step one, advanced geological exploration and prediction;

[0012] Step two, tunnel body bias section excavation;

[0013] Step three, blasting construction;

[0014] Step four, advanced support and continuous grouting using adjusting valve;

[0015] Step five, monitoring and measurement.

[0016] Preferably, in the step one, the geological radar is used as a detection means to detect the geological conditions within thirty meters in front of the tunnel, and the geological radar is used to detect the development of the cave and the broken rock mass on the tunnel floor and both sides, then the advanced drilling method is used for detection, mainly using the advanced horizontal core drilling, supplemented by shallow hole drilling, the underground water affecting the tunnel excavation construction is understood and released through the drilling, the unstable rock stratum and fault fracture zone in front of the tunnel excavation are accurately positioned through core observation and analysis, and the rock physical and mechanical property parameters are obtained through various compression strength tests of the core samples.

[0017] Preferably, in the step two, the annular excavation core soil reservation excavation method is used for construction, specifically comprising:

[0018] Step 1, upper arc-shaped guide hole excavation A, B, C: after the arch advanced support, the upper arc-shaped guide hole is excavated in a ring shape, the core soil is reserved, the excavation cycle footage should be determined according to the initial support steel frame spacing, and the maximum should not exceed 0.75m, 3-5cm of concrete is immediately sprayed after excavation, and the spraying, anchoring and mesh system support are timely performed after excavation;

[0019] Step 2, performing upper section initial support ①;

[0020] Step 3, excavating upper section core soil D;

[0021] Step 4, excavating lower section E, the maximum is not more than two arch frames;

[0022] Step 5, making lower section initial support ②, ③;

[0023] Step 6, invert initial support closure ④;

[0024] Step 7, making invert secondary lining ⑤;

[0025] Step 8, invert backfill ⑥.

[0026] Preferably, in step three, the blasting of the arch of the upper section of the tunnel adopts the micro-vibration straight slotting form, the blasting strength of the slotting blasting is reduced, the deformation of the surrounding rock is controlled, the stability of the surrounding rock is maintained, the blasting excavation is carried out, the artificial drilling of the drilling rig is adopted, the non-electric millisecond detonator is used for differential initiation, the peripheral hole adopts the small-diameter charge of the φ25mm small-diameter cartridge, the remaining blast holes adopt continuous charging, the emulsion waterproof explosive is selected for the water-rich section, the central control straight slotting mode is adopted for the slotting hole, the 1-19 section plastic booster is adopted as the blasting material, the booster detonator is used for initiation, and the emulsion explosive with low blasting speed, low density, high blasting force and good transmission is used for the peripheral hole.

[0027] Preferably, in step three, the drilling and blasting method excavation operation process is composed of measurement and setting out, hole arrangement, trolley and water pipeline positioning, hole drilling, charging and plugging, connection and initiation network, initiation, ventilation, top finding and dangerous stone cleaning, slag removal and bottom cleaning.

[0028] Preferably, in step four, the arch of the small-clearance bias section of the tunnel V-grade surrounding rock is provided with a Φ42 small guide pipe for grouting pre-support, a rock drilling rig is used to drill along the arch contour line, the small guide pipe is installed after the hole is formed, the small guide pipe is firmly welded into the abdomen and the initial support steel frame, the C25 concrete is sprayed along the small guide pipe to form a grout stop disc, and the grouting pump is used for grouting operation.

[0029] Preferably, in step four, two soft branch pipes are respectively communicated and fixed with two grouting interfaces on both sides of the adjusting valve, and the two soft branch pipes are respectively communicated with the end portions of the adjacent two small guide pipes, the grouting pipe is communicated with the external grouting pump, the adjusting knob is twisted and communicated with one soft branch pipe, after the grouting pump is started, the slurry is injected into one small guide pipe through one soft branch pipe, after the grouting of the small guide pipe is completed, the adjusting knob is twisted to communicate the adjusting port with the other soft branch pipe, at this time, the next small guide pipe can be grouted, then the valve at the end portion of the small guide pipe is closed, the soft branch pipe is removed and communicated with the next small guide pipe, the above steps are repeated until all the small guide pipes are grouted from bottom to top, and uninterrupted continuous grouting is realized.

[0030] Compared with the prior art, the beneficial effects of the present application are:

[0031] This invention features a regulating valve connected to the end of the grouting pipe, with flexible branch pipes connected to both sides of the regulating valve. Each flexible branch pipe is connected to one of two pre-grouting small guide pipes. A valve core is rotatably installed inside the regulating valve, with one end open and connected to the grouting pipe. An adjustment port on the surface of the valve core connects to one of the flexible branch pipes. After grouting is completed in one pre-grouting small guide pipe, the valve core is turned to connect the adjustment port to another flexible branch pipe, allowing grouting to proceed to the next pre-grouting small guide pipe. Then, one flexible branch pipe is separated from one pre-grouting small guide pipe and connected to the next pre-grouting small guide pipe, and this cycle is repeated. This allows for uninterrupted grouting of multiple pre-grouting small guide pipes one by one, resulting in higher grouting efficiency and speed. Attached Figure Description

[0032] Figure 1 This is a schematic cross-sectional view of the tunnel structure of the present invention;

[0033] Figure 2 This is a three-dimensional schematic diagram of the overall structure of the present invention;

[0034] Figure 3 This is a schematic diagram showing the connection between the grouting pipe and the advanced small guide tube of the present invention;

[0035] Figure 4 This is an exploded view of the regulating valve structure of the present invention.

[0036] In the diagram: 1. Initial support steel frame; 2. Pre-extension small guide pipe; 21. Grout outlet hole; 22. Valve; 3. Grouting pipe; 4. Regulating valve; 41. Grout outlet interface; 42. Sealing cover plate; 43. Limiting block; 5. Flexible branch pipe; 6. Valve core; 61. Adjustment port; 62. Connecting shaft; 63. Adjustment knob; 64. Pointing block. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the present invention clear and complete, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some, not all, embodiments of the present invention, and are merely illustrative of the embodiments of the present invention. They are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In the description of the present application, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "one", "first", "second", "third", "fourth", "fifth", "sixth" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0039] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] For the purpose of simplicity and illustration, the principles of the embodiments are mainly described by reference to examples. In the following description, many specific details are presented to provide a thorough understanding of the embodiments. However, it is obvious that these embodiments can not be limited to these specific details in practice. In some examples, well-known methods and structures are not described in detail to avoid unnecessarily complicating these embodiments. In addition, all embodiments can be used in combination with each other.

[0041] Please refer to Figures 1 to 4 , the present application provides a technical solution:

[0042] Embodiment one, a mountain V-class surrounding rock small clear distance bias tunnel advance support, comprising: initial support steel frame 1 and grouting pipe 3.

[0043] Specifically, a plurality of advance small catheters 2 are arranged in a ring array on the side of the initial support steel frame 1, the advance small catheters 2 are inserted into the surrounding rock obliquely, as shown in Figure 2 When the advance small catheter 2 is grouted, the concrete slurry can be deeply grouted into the surrounding rock to improve the support strength, one end of the advance small catheter 2 is provided with a valve 22, a plurality of plum blossom-shaped grouting holes 21 are formed on the surface of the advance small catheter 2, the valve 22 is arranged to prevent the slurry from flowing, the grouting holes 21 are arranged to facilitate the slurry to deeply penetrate into the surrounding rock, and the front end of the advance small catheter 2 is arranged in a sharp cone shape to facilitate insertion into the surrounding rock;

[0044] Secondly, one end of the grouting pipe 3 is connected to a regulating valve 4, and the outside of the regulating valve 4 is connected to two flexible branch pipes 5, and the two flexible branch pipes 5 are respectively connected to one end of two advanced small guide pipes 2, such as... Figure 3 As shown, the grouting pipe 3 delivers grout, which is injected into the pre-conduit pipe 2 under the control of the regulating valve 4. The regulating valve 4 is a hollow cylindrical shape with a valve core 6 rotatably mounted inside. The valve core 6 is a cylindrical shape with one end open, and its surface has an adjustment port 61 corresponding to a flexible branch pipe 5. When the valve core 6 rotates, it can control whether the flexible branch pipe 5 is connected to the grouting pipe 3. A sealing gasket is provided between the surface of the valve core 6 and the inner wall of the regulating valve 4. Figure 4 As shown, since there is only one regulating port 61 on the surface of the valve core 6, the grout in the grouting pipe 3 can only be delivered into the inner cavity of one flexible branch pipe 5 to grout one advance small guide pipe 2. By turning the valve core 6, one of the two flexible branch pipes 5 can be connected to the grouting pipe 3. Since this device connects two advance small guide pipes 2 at a time, after one of the advance small guide pipes 2 is grouted, the connection state of the advance small guide pipe 2 can be quickly switched by turning the valve core 6, so that this device can directly inject grout into the next advance small guide pipe 2 without interruption, thereby improving the grouting efficiency.

[0045] To limit the rotation of the valve core 6, this application also includes two slurry outlet ports 41 fixedly connected to both sides of the surface of the regulating valve 4. Two flexible branch pipes 5 are respectively connected to the two slurry outlet ports 41. The flexible branch pipes 5 are flexible and can be quickly connected to other advanced small guide pipes 2 after being removed. The open end of the regulating valve 4 is covered with a sealing cover plate 42 by bolts. An arc-shaped limiting block 43 is fixedly provided on the surface of the sealing cover plate 42. One end of the valve core 6 is fixedly connected to a connecting shaft 62, and the connecting shaft 62 passes through the sealing cover plate 42. An adjusting knob 63 is fixedly provided on one end of the connecting shaft 62, and a pointing block 64 is fixedly provided on the surface of the connecting shaft 62. The pointing block 64 is aligned with the adjusting port 61 and fits against one end face of the limiting block 43. Figure 4 As shown, the adjustment knob 63 is fixed to the valve core 6 via the connecting shaft 62, so that the operator can rotate the valve core 6. The cooperation between the pointing block 64 and the limit block 43 can limit the rotation of the valve core 6, so as to prevent the valve core 6 from rotating too much and causing the adjustment port 61 and the slurry outlet port 41 to misalign.

[0046] This invention also discloses a construction method for advance support of a small-clearance biased tunnel in Class V mountain surrounding rock, specifically including the following steps:

[0047] Step 1: Advanced geological exploration and forecasting;

[0048] Step 2: Excavation of the eccentric pressure section of the tunnel body;

[0049] Step three, blasting construction;

[0050] Step four, advance support and continuous grouting using regulating valve 4;

[0051] Step five, monitoring measurement.

[0052] In order to determine the detection method, the application also has in step one, using geological radar as detection means, short distance detection of geological conditions within thirty meters in front, at the same time using geological radar to detect the cave development and rock mass broken condition of tunnel floor and both sides, then using advanced drilling method for detection, mainly using advanced horizontal core drilling, supplemented by shallow hole drilling, through drilling to understand and release the underground water affecting tunnel excavation construction, through core observation and analysis to accurately locate the unstable rock stratum and fault fracture zone in front of tunnel excavation, directly taking core sample to obtain rock physical and mechanical property parameters through various compressive strength tests;

[0053] In order to save construction time and reduce expenses, for the section with stable geological conditions, hard and complete lithology and small changes, the advanced horizontal core drilling workload can be appropriately reduced, in the drilling process, the drill bit deviation is avoided as much as possible to cause detection result error, according to the hardness of rock, the drilling machine speed and drilling pressure are adjusted, lower drilling pressure is used for hard rock, geological drilling machine is used for advanced deep hole drilling, the drilling depth can reach 150m, the hole diameter is 90-120mm;

[0054] The detection hole arrangement is closely combined with construction process, part of the excavation is drilled first, 3 detection holes are arranged for each section, the hole depth is 30m, and the lap length is 5m.

[0055] In order to determine the excavation step, the application also has in step two, using ring excavation core soil reservation method for construction, according to the engineering hydrogeological conditions, the advanced support is well done according to the design requirements to prevent surrounding rock relaxation and ensure tunnel excavation safety, in fault, fracture zone, shallow buried section and other poor self-stability or water-rich strata, the advanced support should be strengthened according to the design requirements, the specific steps include:

[0056] Step 1, upper arc guide hole excavation A, B, C: after arch advance support, the upper arc guide hole is excavated in ring, the core soil is reserved, the core soil length is 3-5m, and the width is 1 / 3-1 / 2 of the tunnel excavation width. The excavation cycle footage should be determined according to the initial support steel frame spacing, which should not be more than 0.75m, 3-5cm concrete is immediately sprayed after excavation, and spraying, anchoring and net system support are timely carried out after excavation;

[0057] Step 2, upper section initial support ① is made;

[0058] Step 3, upper section core soil D is excavated;

[0059] Step 4, excavate the lower section E, not more than two arches;

[0060] Step 5, make the lower section initial support ②, ③;

[0061] Step 6, close the inverted arch initial support ④;

[0062] Step 7, make the inverted arch secondary lining ⑤;

[0063] Step 8, inverted arch backfill ⑥.

[0064] In order to describe the blasting process in detail, the application also has in step three, the arch of the upper half of the tunnel section is blasted by using micro-vibration straight-hole cutting, which reduces the seismic intensity of cutting blasting and controls the deformation of surrounding rock to maintain the stability of surrounding rock. Since the bias section is generally V-class surrounding rock, the excavation of V-class surrounding rock section should adhere to the principle of "short footage, weak blasting, strong support, and fast closure". In order to avoid collapse, in addition to strengthening the initial support, the blasting vibration effect should be minimized to reduce the disturbance to the surrounding rock of the tunnel and maintain the stability of the surrounding rock. Micro-vibration blasting technology should be used, and reasonable blasting parameters and process should be selected to effectively control vibration and achieve a more ideal vibration effect in soft and broken sections and shallow tunnel sections.

[0065] Secondly, the blasting excavation is manually drilled on the drilling rig, the non-electric millisecond detonator is used for differential initiation, the peripheral hole adopts φ25mm small-diameter cartridge charge without corner charge, the rest of the blast holes adopt continuous charge, emulsion waterproof explosive is selected for water-rich sections, the cutting hole adopts middle-control straight-hole cutting method, and 1-19 section plastic booster is used as the blasting material, the booster detonator is used for initiation, and the peripheral hole adopts emulsion explosive with low blasting speed, low density, high explosive force, and good transmission.

[0066] The blasting explosive quantity is calculated as follows:

[0067] The maximum initiation explosive quantity of micro-vibration blasting is calculated by the following formula, and vibration monitoring is performed on adjacent tunnels and shallow section structures to adjust the blasting scheme in time:

[0068] Qmax = R3 x (Vkp / K)3 / a

[0069] In the formula: Qmax is the maximum blasting explosive quantity, unit kg

[0070] Vkp is the safety speed, unit cm / s, V=2 cm / s

[0071] R is the blasting safety distance

[0072] K is the terrain and geological influence coefficient, K=150

[0073] A is the attenuation coefficient, a=0.16.

[0074] To further supplement the blasting process points, the application also has in step three, drill and blast excavation operation process composition: measurement lofting, eye, trolley and wind water pipeline in place, drilling, charging plug, connection detonation network, detonation, ventilation, find top clear dangerous rock, slag and clean bottom, specifically:

[0075] Lofting eye: the center line construction control point, horizontal construction control point every 10 m set one, every 50 meters from the excavation surface is buried a center line pile, every 100 meters set a temporary level point; before drilling, using total station instrument, level, steel ruler, cooperate, determine the excavation section center line, horizontal line, red paint draw the excavation section contour line, mark the position of blast hole, after inspection meet the design requirements can drill;

[0076] Positioning eye: using pneumatic rock drill drilling, its axis and tunnel axis should be kept parallel, according to the blast hole layout drawing on the drawing point positioning drilling, for slotting eye and peripheral eye drilling precision requirements than other holes, opening error control within 5 cm;

[0077] Drilling: according to different hole position, drill worker positioning, drill worker familiar with the blast hole layout drawing, can operate rock drilling machinery skillfully, especially for drilling peripheral eye, must be by the old drill worker with rich experience, have a special person to command, ensure the accurate external angle of peripheral eye, make the two blast hole interface step not more than 15 cm, at the same time, according to the eye position rock concave and convex degree adjustment blast hole depth, ensure the blast hole eye bottom in the same plane;

[0078] Hole cleaning: after drilling, should be strictly checked, according to the blast hole layout drawing inspection and make a good record, have not meet the requirements of blast hole should be re drilled, after inspection can charge blasting; before charging, must use by the steel bend of hook and less than the diameter of blast hole high pressure air pipe input high pressure air blast hole stone and blow out;

[0079] Charging: charging need to be divided into pieces, according to the blast hole design chart to determine the charging quantity from top to bottom, detonator "number", positioning, segment, do not mix, all blast hole with mortar plug, plug length is not less than 20 cm, from the top of the cartridge plug, do not just plug in the eye;

[0080] In addition, to ensure the drilling quality measures: unified command, coordinate action, seriously implement the "five" post responsibility system of person, position, machine, quality, quantity; drilling according to the order, avoid mutual interference, collision, crowded; fixed shift, skilled operation, master the law, improve the speed and accuracy of drilling.

[0081] In order to determine the construction method of the advanced support, the application further has that in step four, a Φ42 small duct grouting advanced support is arranged at the arch of the tunnel V-grade surrounding rock small-spacing bias section, a rock drill is used to drill along the arch excavation contour line, the small duct 2 is installed after the hole is formed, the small duct 2 is firmly welded into the abdomen and the initial support steel frame 1, the line spraying C25 concrete is arranged along the small duct 2 to form a grout stop disc, and the grouting operation is performed by using a grouting pump;

[0082] The small duct 2 is made in a component processing factory, the front end is tapered to be inserted into the surrounding rock, the tail is welded with a φ8mm reinforcing bar stiffening hoop for positioning, and holes are staggered drilled on the pipe wall every 15cm with a diameter of 6-8mm; the small duct 2 is inserted into the hole after drilling, and is punched in by using an air gun when it is difficult to insert, and the small duct 2 is welded with the initial support steel frame 1 to form a pre-support system;

[0083] Secondly, the grouting equipment adopts a KBY-50 / 70 grouting pump, the cement grout pressure is not greater than 2MPa, the grouting process is strictly performed according to the design and construction specification, the grout stop disc is formed by spraying 5-10cm of concrete to close the working face before grouting, the grouting is ended when the single-hole grouting reaches the designed amount, and the grouting parameters are adjusted according to the grouting test results and the site conditions.

[0084] In order to describe the grouting step of the advanced support in detail, the application further has that in step four, two soft pipes 5 are respectively fixed and communicated with two grout outlets 41 on both sides of the adjusting valve 4, and the two soft pipes 5 are respectively communicated with the end portions of two adjacent small ducts 2, the grouting pipe 3 is communicated with an external grouting pump, the adjusting knob 63 is twisted and the adjusting port 61 is communicated with one soft pipe 5, at this time, after the grouting pump is started, the slurry is grouted into one small duct 2 along one soft pipe 5, after the grouting of the small duct 2 is completed, the adjusting knob 63 is twisted to make the adjusting port 61 communicated with the other soft pipe 5, at this time, the next small duct 2 can be grouted, then the valve 22 at the end portion of one small duct 2 is closed, the soft pipe 5 at this position is disassembled and communicated with the next small duct 2, the above steps are repeated, until all the small ducts 2 are grouted from bottom to top, and uninterrupted continuous grouting is realized.

[0085] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A kind of mountain V class surrounding rock small pitch bias tunnel advance support, it is characterized by: Include: The initial support steel frame (1) is provided with a plurality of small advance ducts (2) arranged in a ring array on the side surface, the small advance ducts (2) are inserted into the surrounding rock in an inclined manner, one end of the small advance duct (2) is provided with a valve (22), and a plurality of grout outlets (21) are arranged on the surface of the small advance duct (2) in a plum blossom shape; The grouting pipe (3) is communicated with the adjusting valve (4) at one end, the outer side of the adjusting valve (4) is communicated with two soft branch pipes (5), and the two soft branch pipes (5) are respectively communicated with one end of the two small advance ducts (2), the adjusting valve (4) is provided in a hollow cylinder shape, and a valve core (6) matched with the adjusting valve (4) is rotatably installed inside, the valve core (6) is provided in a cylindrical shape with one end open, and a plurality of adjusting openings (61) corresponding to one soft branch pipe (5) are arranged on the surface of the valve core (6), and a sealing gasket is arranged between the surface of the valve core (6) and the inner wall of the adjusting valve (4); The surface of the adjusting valve (4) is fixedly connected with a grout outlet (41) on both sides, the two soft branch pipes (5) are respectively communicated with the two grout outlets (41), the open end of the adjusting valve (4) is covered with a sealing cover plate (42) fixed by bolts, an arc-shaped limiting block (43) is fixedly arranged on the surface of the sealing cover plate (42), one end of the valve core (6) is fixedly connected with a connecting shaft (62), and the connecting shaft (62) penetrates the sealing cover plate (42), an adjusting knob (63) is fixedly arranged on one end of the connecting shaft (62), and a pointing block (64) is fixedly arranged on the surface of the connecting shaft (62), the pointing block (64) is aligned with the adjusting opening (61) and abuts against one end surface of the limiting block (43); By communicating the adjusting valve (4) with the grouting pipe (3) at one end, the soft branch pipes (5) are communicated on both sides of the adjusting valve (4), the two soft branch pipes (5) are respectively communicated with the two small advance ducts (2), the valve core (6) is rotatably installed in the adjusting valve (4), one end of the valve core (6) is open and communicated with the grouting pipe (3), the adjusting opening (61) is arranged on the surface of the valve core (6) and communicated with one soft branch pipe (5), when the grouting of one small advance duct (2) is completed, the adjusting opening (61) is communicated with another soft branch pipe (5) by rotating the valve core (6), and the grouting of the next small advance duct (2) can be realized, then the soft branch pipe (5) is separated from one small advance duct (2) and communicated with the next small advance duct (2), and the cycle can be realized to realize uninterrupted grouting of multiple small advance ducts (2).

2. The construction method of the advanced support of the mountain V-grade surrounding rock small-clearance bias tunnel according to claim 1, characterized in that: Specifically includes the following steps: Step one, advanced geological exploration and prediction; Step two, tunnel body bias section excavation; Step three, blasting construction; Step four, advance support and continuous grouting using the adjusting valve (4); Step five, monitoring and measurement.

3. The construction method of the advanced support of the mountain V-class surrounding rock small-clearance bias tunnel according to claim 2, characterized in that: In the step one, the geological radar is used as the detecting means to detect the geological conditions within 30 meters in front, and meanwhile, the geological radar is used to detect the development of karst cave and the broken rock mass on the tunnel floor and both sides. Then, the advanced drilling method is used to detect, mainly the advanced horizontal core drilling, supplemented by the shallow hole drilling. Through the drilling, the underground water affecting the tunnel excavation construction is understood and released, and through the core observation and analysis, the unstable rock stratum and fault fracture zone in front of the tunnel excavation are accurately positioned, and the rock core sample is directly taken to conduct various compression strength tests to obtain the rock physical and mechanical property parameters.

4. The construction method of the advanced support of the mountain V-class surrounding rock small-clearance bias tunnel according to claim 3, characterized in that: In the step two, the annular excavation reserved core soil excavation method is used for construction, specifically including: Step 1, upper arc-shaped guide pit excavation A, B, C: after the arch advance support, the annular upper arc-shaped guide pit is excavated, the core soil is reserved, the excavation cycle footage should be determined according to the initial support steel frame spacing, and the maximum should not exceed 0.75 m. After excavation, 3-5 cm of concrete is immediately sprayed, and the spraying, anchoring and mesh system support is timely performed after excavation; Step 2, performing upper section initial support ①; Step 3, excavating upper section core soil D; Step 4, excavating lower section E, the maximum is not more than two arch frames; Step 5, performing lower section initial support ②, ③; Step 6, closing the inverted arch initial support ④; Step 7, performing inverted arch secondary lining ⑤; Step 8, inverted arch backfill ⑥.

5. The construction method of the advanced support of the mountain V-class surrounding rock small-clearance bias tunnel according to claim 4, characterized in that: In the step three, the micro-vibration straight-hole slotting form is used for blasting in the arch of the upper half section of the tunnel, the seismic intensity of the slotting blasting is reduced, the deformation of the surrounding rock is controlled, the stability of the surrounding rock is maintained, the blasting excavation is performed, the drilling rig is manually drilled, the non-electric millisecond detonator is used for differential initiation, the peripheral hole uses the φ25 mm small-diameter cartridge without corner charging, the rest of the blast holes use continuous charging, the emulsion waterproof explosive is selected for the water-rich section, the slotting hole uses the central control straight-hole slotting method, the blasting material uses the 1-19 section plastic booster, the booster is initiated, and the peripheral hole uses the emulsion explosive with low blasting speed, low density, high blasting force and good transmission.

6. The construction method of the advanced support of the mountain V-class surrounding rock small-clearance bias tunnel according to claim 5, characterized in that: In the step three, the drilling and blasting method excavation operation process is composed of: measurement and lofting, hole arrangement, rig and air and water pipeline positioning, hole drilling, charging and plugging, connection and initiation network, initiation, ventilation, top finding and dangerous stone cleaning, slag removal and bottom cleaning.

7. The construction method of the advanced support of the mountain V-grade surrounding rock small-clearance bias tunnel according to claim 6, characterized in that: In the step four, the Φ42 small duct grouting advance support is arranged in the arch of the tunnel V-class surrounding rock small clear distance bias pressure section, the rock drilling rig is used to drill along the arch excavation contour line, the small duct is installed after the hole is formed, the small duct is firmly welded with the initial support steel frame in the abdomen, the line spraying C25 concrete is arranged along the small duct to form the grout stop disc, and the pressure grouting pump is used for pressure grouting operation.

8. The construction method of the advanced support of the mountain V-grade surrounding rock small clear distance bias tunnel according to claim 7, characterized in that: The step four, two soft branch pipes (5) are respectively communicated with two slurry outlet interfaces (41) on both sides of the adjusting valve (4) and fixed, and the two soft branch pipes (5) are respectively communicated with the end portions of two adjacent advanced small conduits (2), the grouting pipe (3) is communicated with the external pressure grouting pump, the adjusting knob (63) is screwed and the adjusting port (61) is communicated with one soft branch pipe (5), after the pressure grouting pump is started, the slurry liquid is injected into one advanced small conduit (2) along one soft branch pipe (5), after the slurry injection of the advanced small conduit (2) is completed, the adjusting knob (63) is screwed to make the adjusting port (61) communicated with another soft branch pipe (5), at this time, the next advanced small conduit (2) can be injected, then the valve (22) at the end portion of the advanced small conduit (2) is closed, the soft branch pipe (5) is removed and communicated with the next advanced small conduit (2), the above steps are repeated until all the advanced small conduits (2) are injected from bottom to top, the uninterrupted continuous grouting is realized.

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