A soft rock dynamic pressure roadway supporting method using a combined supporting device

Abstract

The application relates to the technical field of roadway supporting, and provides a soft rock dynamic pressure roadway supporting method adopting a combined supporting device, which comprises the following steps: S1, prefabricating a connecting piece 5 and a supporting unit; S2, performing double-gradient grouting on roadway surrounding rock; S3, constructing a roadway surrounding rock anchoring system; S4, installing a bearing plate on the roadway surrounding rock; S5, according to the shape of a roadway section, splicing the connecting piece and a plurality of the supporting units to form a rectangular roadway combined supporting device or a three-star arch roadway combined supporting device; S6, installing a displacement sensor, a pressure sensor group and a controller; S7, performing floor heave construction; and S8, dynamically supporting and regulating. The application provides a combined supporting device integrating "active support-real-time monitoring-dynamic compensation-floor reinforcement", and solves the multi-dimensional deformation problem of an extremely soft rock dynamic pressure roadway through structural innovation and construction process optimization.

Description

Technical Field

[0001] This application relates to the field of roadway support technology, and in particular to a method for supporting soft rock dynamic pressure roadways using a combined support device. Background Technology

[0002] In deep mining, traditional roadway layouts often neglect the influence of the direction of ground stress. When the direction of ground stress is perpendicular to the roadway axis, the roadway is susceptible to significant horizontal stress, leading to deformation and damage such as roof subsidence and sidewall shrinkage. Especially in extremely soft rock formations, stress concentration can cause severe floor heave. Furthermore, because the distribution of the ground stress field is not effectively integrated with the support structure design, it is difficult to cope with the multi-dimensional deformation challenges under dynamic pressure in extremely soft rock. Simultaneously, extremely soft rock roadways under dynamic pressure often face challenges such as sudden roof subsidence, sidewall plastic flow shrinkage, and severe floor heave due to stress concentration caused by repeated disturbances from mining, due to the low rock mass strength, high content of expansive minerals such as montmorillonite, and repeated disturbances from mining stress. Traditional passive support (such as anchor bolts and cables + shotcrete) has shortcomings such as insufficient reinforcement depth, inability to adapt to dynamic deformation, and lack of stress cutoff mechanisms for floor heave control. In particular, it lacks an integrated solution of "surrounding rock reinforcement - active support - intelligent monitoring," making it difficult to effectively address the multi-dimensional deformation and damage of extremely soft rock roadways under dynamic pressure.

[0003] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0004] To address the above issues, this application provides a combined support device integrating "active support, real-time monitoring, dynamic compensation, and floor reinforcement." Through structural innovation and construction process optimization, it solves the multi-dimensional deformation problem in extremely soft rock dynamic pressure roadways.

[0005] This application relates to a method for supporting soft rock dynamic pressure roadways using a combined support device, the improvement of which is that the support method includes:

[0006] Step S1: Prefabricate connector 5 and support unit; connector 5 includes a metal block; support unit includes rod-shaped hydraulic strut 2;

[0007] Step S2 involves performing dual-gradient grouting on the surrounding rock of the tunnel, including:

[0008] Step S2-1, shallow hole low pressure coarse-grained grouting;

[0009] Step S2-2: Deep hole high-pressure fine-grain grouting;

[0010] Step S3, construction of the roadway surrounding rock anchoring system; the anchoring system includes anchor bolts and anchor cables that are uniformly constructed along the radial direction of the roadway and added along the axial direction of the roadway;

[0011] Step S4: Install bearing plate 1 in the surrounding rock of the tunnel; the bearing plate 1 is a plate-shaped object, and a flat rectangular or arc-shaped bearing plate is selected according to the cross-section of the tunnel; if it is a rectangular tunnel, a flat rectangular bearing plate is selected; if it is a three-star arch tunnel, an arc-shaped bearing plate is selected.

[0012] The support plate 1 includes a plate-shaped object, which is uniformly disposed on the tunnel wall; the first surface of the support plate 1 is attached to the tunnel wall.

[0013] Step S5: According to the cross-sectional shape of the roadway, the connecting piece 5 and multiple support units are spliced ​​together to form a rectangular roadway joint support device or a three-star arch roadway joint support device; the first end of the hydraulic prop 2 is set on the connecting piece 5; the second end of each hydraulic prop 2 is connected to the second surface of the corresponding bearing plate 1.

[0014] Step S6: Install displacement sensor 3, pressure sensor group 6, and controller; install displacement sensor 3 on the side wall of the second end of hydraulic support 2; install pressure sensor group 6 on the end face of hydraulic support 2 that contacts bearing plate 1; install controller in connector 5;

[0015] Step S7, Heave construction; in severely heave areas with a heave rate > 5 mm / day, construct bottom corner grouting anchor pipes; in other heave areas, construct ordinary bottom corner anchor bolts;

[0016] Step S8, dynamic support control; when the roof sinks, the bearing plate 1 compresses the hydraulic prop 2, the displacement sensor monitors the compression of the hydraulic prop 2 and sends a displacement signal to the controller. The controller receives the displacement signal and feeds back a control signal to the hydraulic prop, so that the hydraulic prop automatically replenishes fluid to continue to provide support force to the bearing plate 1.

[0017] Preferably, step S2-1, shallow hole low-pressure coarse-grained grouting, includes: constructing shallow grouting holes 11 in the surrounding rock at the top of the roadway using a Φ42mm drill bit; the shallow grouting holes are 2-3m deep, 1.5-2.0m apart, arranged in a quincunx pattern, with an inclination angle of 10°-15°; the grouting material for the shallow grouting holes is: 42.5 grade ordinary Portland cement and river sand in a ratio of 1:0.5, water-cement ratio of 1:1.2, with 3% UEA expansion agent added; the grouting pressure is 0.5-1.0 MPa; grouting ends when grout returns from the shallow grouting holes or when the grouting volume reaches the theoretical value, forming a shallow closed reinforcement ring with a thickness of 2-3m.

[0018] Preferably, step S2-2, deep-hole high-pressure fine-grained grouting, includes: constructing deep-hole grouting holes 12 next to the shallow-hole grouting holes 11 using a Φ56mm drill bit; the deep-hole grouting holes are 5-8m deep, 2.5-3.0m apart, and arranged at intervals with the shallow holes, with an inclination angle of 5°-10°; the grouting material for the deep-hole grouting holes is: a mixture of 42.5 grade cement and silica fume, with a water-cement ratio of 1:0.8, and a cement-water glass two-liquid grout volume ratio of 1:0.6, with a water glass concentration of 35Be′.

[0019] Preferably, if the roadway is rectangular, then a rectangular roadway combined support device is selected;

[0020] The rectangular roadway combined support device includes a first combined support device and a second combined support device connected by a hydraulic connecting rod 4; the second combined support device is symmetrically arranged with the first combined support device, and each includes:

[0021] Rigid cube connector; three support units are provided on the rigid cube; the first support unit is perpendicular to the ground; the second support unit is parallel to the ground; the third support unit is obliquely downward and at an acute angle to the second support unit;

[0022] The first and second combined support devices are added along the axial direction of the rectangular roadway to form a combined support device for the rectangular roadway.

[0023] Preferably, if it is a three-star arch tunnel, then the three-star arch tunnel combined support device shall be selected;

[0024] The Samsung Arch Tunnel Joint Support Device includes Samsung Arch Tunnel Joint Support Units added along the tunnel axis; each Samsung Arch Tunnel Joint Support Unit includes: a rigid circular ring connector; five support units are arranged on the rigid circular ring connector; the first support unit is perpendicular to the ground and is located on the top of the rigid circular ring connector; the second and third support units are respectively located on both sides of the first support unit, with the second and third support units forming an angle of 50° to 75° with the first support unit; the fourth support unit is located outside the second support unit, forming an angle of 50° to 75° with the second support unit; and the fifth support unit is located outside the third support unit, forming an angle of 50° to 75° with the third support unit.

[0025] Preferably, step S7, bottom heave construction, includes: constructing a bottom corner grouting anchor pipe with a depth of 3.5m within the severely heaved area, and injecting double-liquid grout at a pressure of 2.5MPa to form a reinforced column; the bottom corner grouting anchor pipe includes a seamless steel pipe with a diameter of Φ42mm × wall thickness of 4mm, and the length of the bottom corner grouting anchor pipe is 3.5m; grouting holes with a hole spacing of 150mm and a diameter of Φ8mm are opened at the front end of the bottom corner grouting anchor pipe, and a rubber grout stop plug is installed at the tail end of the bottom corner grouting anchor pipe.

[0026] Preferably, the feature is that, in step S7, the ordinary bottom corner anchor rods used for bottom heave construction include: 2.5m long, Φ22mm, HRB400 steel anchor rods, with a row spacing of 1.0m×1.2m between the steel anchor rods; the shallow deformation of the bottom plate is suppressed by pre-tightening the tray.

[0027] Compared with the closest prior art, the technical solution of this application has the following beneficial effects:

[0028] 1. Dual-gradient grouting process: By "shallow hole low pressure coarse particle sealing + deep hole high pressure fine particle reinforcement", the surrounding rock is reinforced from the surface to the inside, which solves the contradiction between grouting penetration and strength improvement in extremely soft rock.

[0029] 2. Intelligent dynamic support structure: The hydraulic support and the intermediate connecting rod form a triangular stable system. Combined with displacement-pressure dual sensors for linkage pressure compensation, the response time is <3s, realizing adaptive control of support force under dynamic pressure environment;

[0030] 3. Graded control mode for bottom heave: Differentiated use of bottom corner grouting anchor pipes or ordinary anchor bolts according to the severity of bottom heave, to improve the economy and targetedness of support. Attached Figure Description

[0031] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein:

[0032] Figure 1 This is a schematic diagram of the rectangular tunnel combined support device involved in this application;

[0033] Figure 2 This is a schematic diagram of the rectangular tunnel support involved in this application;

[0034] Figure 3 This is a schematic diagram of the support device for the Samsung arch tunnel involved in this application;

[0035] Figure 4 This is a schematic diagram of the connection of the bearing plate involved in this application;

[0036] Figure 5 This is a schematic diagram of the construction of the dual-gradient grouting and bottom corner grouting anchor pipe involved in this application;

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Bearing plate; 2. Hydraulic support; 3. Displacement sensor; 4. Hydraulic connecting rod; 5. Connector; 6. Pressure sensor group; 7. Anchor bolt; 8. Anchor cable; 9. Concrete shell; 10. Bottom corner grouting anchor pipe; 11. Shallow hole grouting hole; 12. Deep hole grouting hole. Detailed Implementation

[0039] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present application without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present application encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0040] In the following description, the terms "first / second / third" are used merely to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to limit this disclosure.

[0042] In the description of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and do not require that this application be constructed and operated in a specific orientation, and therefore should not be construed as limiting this application. The terms "connected," "linked," and "set up" used in this application should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; direct connections or indirect connections through intermediate components; wired connections, radio connections, or wireless communication signal connections. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0043] This application relates to a method for supporting soft rock dynamic pressure roadways using a combined support device, characterized in that the support method includes:

[0044] Step S1: Prefabricate the connector 5 and support units; the connector 5 includes a metal block; the support unit includes a rod-shaped hydraulic support 2. Specifically, in subsequent steps, the connector 5 and multiple support units need to be spliced ​​together according to the cross-sectional shape of the roadway to form a support structure corresponding to the cross-sectional shape of the roadway.

[0045] Step S2 involves performing dual-gradient grouting on the surrounding rock of the tunnel, including:

[0046] Step S2-1, shallow-hole low-pressure coarse-grained grouting. Specifically, as follows... Figure 5 As shown, step S2-1, shallow-hole low-pressure coarse-grained grouting, includes: constructing shallow-hole grouting holes 11 in the surrounding rock at the top of the tunnel using a Φ42mm drill bit; the shallow-hole grouting holes are 2-3m deep, 1.5-2.0m apart, arranged in a quincunx pattern, with an inclination angle of 10°-15°. Specifically, the quincunx pattern is a common hole arrangement in grouting hole construction. Its core feature is that the symmetrical distribution of the central hole and the surrounding holes achieves uniform coverage of the grouting holes in the surrounding rock. For shallow-hole low-pressure coarse-grained grouting, this application preferentially selects a square diagonal grouting hole arrangement, that is, the central hole is located at the center of the square, and the four outer holes are located at the four vertices of the square. At this time, the distance from the central hole to the outer hole (i.e., half the diagonal) is slightly greater than the distance between two adjacent outer holes (i.e., the side length of the square), which is suitable for scenarios with small hole spacing requirements and limited working space (such as shallow-hole grouting and small-scale reinforcement). Meanwhile, grouting with inclined holes at an angle of 10°-15° can penetrate deep into the fractured zone of the surrounding rock. After the grout solidifies, it forms a grout vein skeleton with an inclined angle, which is more resistant to lateral or vertical displacement of the surrounding rock than vertical holes. The inclination direction of the grout is preferentially inclined towards the hard rock layer outside the tunnel, because soft rock is prone to hole collapse. Inclining towards hard rock can reduce the risk of tunnel collapse, and at the same time, it allows the grout to form a "support layer" at the interface between hard rock and soft rock to prevent deformation of the soft rock.

[0047] The grouting material for shallow grouting holes is: 42.5 grade ordinary Portland cement and river sand in a ratio of 1:0.5, water-cement ratio of 1:1.2, with 3% UEA expansion agent added; the grouting pressure is 0.5-1.0 MPa; grouting ends when the shallow grouting hole returns grout or the grouting volume reaches the theoretical value (calculated as a coefficient of 1.5 times the duct volume), forming a shallow closed reinforcement ring with a thickness of 2-3m.

[0048] The use of the above-mentioned materials as shallow hole grouting materials also has the following advantages: The 42.5 grade ordinary Portland cement has a moderate strength, which can meet the basic requirements of shallow reinforcement for early strength and later stability. When combined with river sand (1:0.5 ratio), the grout gradation can be optimized, reducing cement usage to control costs, while simultaneously enhancing the skeleton support capacity of the grout body and avoiding structural cracks caused by excessive shrinkage of pure cement grout; the 1:1.2 water-cement ratio balances the fluidity and pumpability of the grout, ensuring that the grout can smoothly diffuse and fill the pores within the shallow hole channels, and also allows for rapid setting and hardening after grouting, avoiding… The problem of insufficient strength due to excessively thin grout or difficulty in injection due to excessively thick grout can be addressed by adding 3% UEA expansion agent. This effectively compensates for the volume shrinkage during the grout hardening process, improves the adhesion between the grout and the rock strata of the borehole wall, and prevents shrinkage cracks from affecting the sealing effect. Combined with a grouting pressure of 0.5-1.0MPa (suitable for the pressure bearing capacity of shallow rock strata) and a termination standard of grout return or reaching the theoretical grouting volume (1.5 times the borehole volume), it can efficiently form a shallow sealing reinforcement ring with a thickness of 2-3m, high density, and strong sealing performance, fully meeting the core requirements of shallow rock strata reinforcement for integrity, stability, and sealing.

[0049] Step S2-2, Deep Hole High-Pressure Fine-Grain Grouting. Specifically, step S2-2, Deep Hole High-Pressure Fine-Grain Grouting, includes: constructing deep hole grouting holes 12 next to the shallow hole grouting holes 11 using a Φ56mm drill bit; the deep hole grouting holes are 5-8m deep, 2.5-3.0m apart, and spaced apart from the shallow holes, with an inclination angle of 5°-10°; the grouting material for the deep hole grouting holes is: a mixture of 42.5 grade cement and silica fume, with a water-cement ratio of 1:0.8, using a cement-water glass two-liquid grout (volume ratio 1:0.6), and a water glass concentration of 35Be′.

[0050] Among these advantages, using the aforementioned materials as deep-hole grouting materials also offers the following benefits: Using a mixture of 42.5 grade cement and silica fume (water-cement ratio 1:0.8) combined with a cement-water glass dual-liquid grout (volume ratio 1:0.6, water glass concentration 35Be′) as the deep-hole grouting material meets the specific performance requirements of deep-hole grouting: 42.5 grade cement ensures foundation strength, silica fume fills the gaps between cement particles, improving the density and impermeability of the grout, and the 1:0.8 water-cement ratio ensures a certain level of grout performance. The fluidity is adapted to accommodate long-distance diffusion in deep holes while reducing later shrinkage and enhancing strength. The cement-water glass dual-liquid grout (1:0.6 volume ratio) combined with 35Be′ concentration water glass can significantly shorten the grout setting time, avoid grout loss due to long diffusion distance and large rock pores during deep hole grouting, and quickly form a solidified body. Moreover, the dual-liquid grout stone body has high strength and good impermeability, which can effectively seal the rock fissures around the deep hole, meeting the core requirements of deep hole grouting for rapid reinforcement, efficient water plugging and long-term stability.

[0051] Step S3, construction of the tunnel surrounding rock anchoring system; such as Figure 5 As shown, the anchoring system includes anchor bolts 7 and anchor cables 8, which are uniformly installed radially along the roadway and added axially along the roadway. Specifically, the anchor bolts 7 and anchor cables 8 can be installed using common roadway support methods, by passing the anchor bolts 7 and anchor cables 8 through the concrete shell 9 of the roadway wall and fixing them inside the roadway wall.

[0052] Step S4: Install bearing plate 1 in the surrounding rock of the tunnel; the bearing plate 1 is a plate-shaped object, and a flat rectangular or arc-shaped bearing plate is selected according to the cross-section of the tunnel; if it is a rectangular tunnel, a flat rectangular bearing plate is selected; if it is a three-star arch tunnel, an arc-shaped bearing plate is selected.

[0053] The bearing plate 1 comprises a plate-shaped object, evenly arranged on the tunnel wall; the first surface of the bearing plate 1 is in contact with the tunnel wall. Specifically, a flat rectangular or arc-shaped bearing plate is selected according to the tunnel cross-section, and the bearing plate 1 is evenly fixed to the surface of the tunnel roof by anchor bolts 7. The method of fixing the bearing plate to the anchor bolts 7 is determined according to the actual situation during construction. Holes can be drilled in the bearing plate before fixing it to the anchor bolts 7.

[0054] Step S5: According to the cross-sectional shape of the roadway, the connecting piece 5 and multiple support units are spliced ​​together to form a rectangular roadway joint support device or a three-star arch roadway joint support device; the first end of the hydraulic prop 2 is set on the connecting piece 5; the second end of each hydraulic prop 2 is connected to the second surface of the corresponding bearing plate 1.

[0055] Preferred, such as Figure 1 As shown, if it is a rectangular roadway, then a rectangular roadway combined support device should be selected;

[0056] The rectangular roadway combined support device includes a first combined support device and a second combined support device connected by a hydraulic connecting rod 4; the second combined support device is symmetrically arranged with the first combined support device, and each includes:

[0057] Rigid cube connector; three support units are provided on the rigid cube; the first support unit is perpendicular to the ground; the second support unit is parallel to the ground; the third support unit is obliquely downward and at an acute angle to the second support unit;

[0058] The first and second combined support devices are added along the axial direction of the rectangular roadway to form a combined support device for the rectangular roadway.

[0059] Specifically, a rectangular roadway is a roadway with a rectangular radial cross-section. A rectangular roadway combined support system includes two combined support devices, a first combined support device and a second combined support device, installed symmetrically with respect to the roadway's axial direction within the same radial cross-section. The first and second combined support devices are connected by a hydraulic connecting rod 4.

[0060] The first and second combined support devices use a rigid cube as the connector 5. A support unit is installed in each of the three directions of the rigid cube. The first support unit is perpendicular to the ground; the second support unit is parallel to the ground; and the third support unit is angled downwards at an acute angle to the second support unit.

[0061] During installation, such as Figure 2 As shown, the first combined support device and the second combined support device are hoisted at a row spacing of 1.5m. The connection length of the hydraulic connecting rod 4 and the support length of the hydraulic support 2 are adjusted so that each support unit is connected to its corresponding bearing plate 1.

[0062] The first and second combined support devices, added along the roadway axis, are connected by a hydraulic system. The hydraulic system is installed on the connecting joint 5 of the two front-to-back first combined support devices; it is also installed on the connecting joint 5 of the two front-to-back second combined support devices, used to adjust the spacing between the first and second combined support devices. After installation, a rectangular roadway combined support system is formed.

[0063] Preferred, such as Figure 3 As shown, if it is a three-star arch tunnel, then the three-star arch tunnel combined support device shall be selected;

[0064] The Samsung Arch Tunnel Joint Support Device includes Samsung Arch Tunnel Joint Support Units added along the tunnel axis. Each Samsung Arch Tunnel Joint Support Unit includes a rigid circular ring connector; five support units are mounted on the rigid circular ring connector; a first support unit is perpendicular to the ground and positioned at the top of the rigid circular ring connector; a second and third support unit are respectively positioned on either side of the first support unit, with the second and third support units forming an angle of 50° to 75° with the first support unit; a fourth support unit is positioned outside the second support unit, forming an angle of 50° to 75° with the second support unit; a fifth support unit is positioned outside the third support unit, forming an angle of 50° to 75° with the third support unit. These Samsung Arch Tunnel Joint Support Device units are added along the tunnel axis to form the Samsung Arch Tunnel Joint Support Device.

[0065] Specifically, the Sanxing Arch tunnel is a tunnel with an arched radial cross-section. Its arch section consists of a main arch and two secondary arches on either side, forming three arch segments that jointly bear the surrounding rock pressure. The Sanxing Arch tunnel's combined support device uses a rigid circular ring connector (connector 5). A support unit is installed in each of the five directions of the rigid circular ring connector, forming a combined support unit for the Sanxing Arch tunnel. The first support unit is perpendicular to the ground and located at the top of the rigid circular ring connector. The second and third support units are symmetrically arranged on either side of the first support unit. The fourth and fifth support units are symmetrically arranged diagonally downwards, with the fourth support unit located outside the second support unit and the fifth support unit located outside the third support unit.

[0066] Preferably, when installing the connector 5 and the hydraulic support 2, such as Figure 1 and Figure 3 As shown, a block-shaped fixing component is also provided; a fixing component is provided on each side of the first end of the hydraulic support 2. The fixing component is welded to the connecting component 5. At the same time, the fixing component is also fixed to the first end of the hydraulic support 2 by a fixing pin, so as to ensure that the position of the hydraulic support 2 is fixed in subsequent steps and that the axial displacement does not occur.

[0067] Step S6, as follows Figure 4 As shown, a displacement sensor 3, a pressure sensor group 6, and a controller are installed; the displacement sensor 3 is installed on the side wall of the second end of the hydraulic support 2; the pressure sensor group 6 is installed on the end face of the hydraulic support 2 that contacts the bearing plate 1; and the controller is installed in the connector 5.

[0068] Specifically, a displacement sensor 3 is installed on each hydraulic support 2 at one end near the bearing plate 1 to monitor the displacement of the second end of the hydraulic support 2, thereby monitoring the degree of roof subsidence. The displacement sensor is a YHW100 type, with a range of 0-100mm and an accuracy of 0.01mm.

[0069] A pressure sensor group 6 is also installed on the end face of the hydraulic prop 2 that contacts the bearing plate 1. The pressure sensor group 6 includes multiple pressure sensors evenly arranged along the circumference of the second end face of the hydraulic prop 2. The pressure sensors are embedded in the cylinder of the hydraulic prop 2 to monitor the pressure of the roadway wall on the hydraulic prop 2, thereby monitoring the support force of the hydraulic prop 2. The pressure sensor is a CYB200 type, with a range of 0-80MPa and an accuracy of 0.1MPa.

[0070] The controller is set in each connector 5 with a preset deformation threshold. When the sinking rate of the top plate is greater than 1.5 mm / h or the cumulative sinking amount is greater than 40 mm, the hydraulic support 2 will be automatically pressurized, and the pressurization rate is 8-12 kN / s.

[0071] Step S7, bottom heave construction; in severely heave areas with a heave rate > 5 mm / day, construct bottom corner grouting anchor pipe 10; in other heave areas, construct ordinary bottom corner anchor rods.

[0072] Among them, such as Figure 5 As shown, within the severely bulging area, a bottom corner grouting anchor pipe 10 with a depth of 3.5m is constructed at the bottom corner, and liquid grout is injected at a pressure of 2.5MPa to form a reinforced column; the bottom corner grouting anchor pipe 10 includes a seamless steel pipe with a diameter of Φ42mm × wall thickness of 4mm, and the length of the bottom corner grouting anchor pipe is 3.5m; grouting holes with a diameter of Φ8mm and a hole spacing of 150mm are opened from the front end to the end of the bottom corner grouting anchor pipe, and a rubber grout stop plug is installed at the tail end of the bottom corner grouting anchor pipe.

[0073] Specifically, in areas of severe floor heave, the location of severe floor heave varies depending on the cross-sectional shape of the tunnel and the stress distribution of the surrounding rock. In rectangular tunnels, where the floor is flat and there is significant stress concentration at the four corners, severe floor heave is mostly concentrated in the middle of the floor and near the sides. The middle section, directly bearing the vertical pressure of the upper rock strata and with weaker lateral restraint, is prone to overall bulging or the development of longitudinal fissures. Near the sides, due to the deformation and compression of the surrounding rock, it is often accompanied by... The bulging at the bottom corner is superimposed with the amount of bottom heave; the three-star arch roadway (the cross-section is shaped like a "three-star arch", and the bottom plate is mostly a gentle arc or a structure with a certain degree of curvature) is affected by the force transmission of the arc cross-section, and the stress is more likely to be dispersed to the arch. The area of ​​severe bottom heave is relatively concentrated in the middle area of ​​the arc section of the bottom plate. In this position, because the arc structure has a weaker ability to buffer vertical pressure, and the arc sections on both sides have a stronger constraint on the middle than the two sides of the rectangular roadway, the bottom heave is mostly manifested as a local bulge in the middle, rather than being evenly distributed along the bottom plate.

[0074] The common bottom corner anchors used in the bottom heave construction include: Φ22mm HRB400 steel anchors, 2.5m in length, with a row spacing of 1.0m (spacing) × 1.2m (row spacing); shallow deformation of the bottom plate is suppressed by pre-tightening with a tray.

[0075] Step S8, dynamic support control; when the roof sinks, the bearing plate 1 compresses the hydraulic prop 2, the displacement sensor monitors the compression of the hydraulic prop 2 and sends a displacement signal to the controller. The controller receives the displacement signal and feeds back a control signal to the hydraulic prop, so that the hydraulic prop automatically replenishes fluid to continue to provide support force to the bearing plate 1.

[0076] Specifically, when the displacement sensor detects a roof settlement rate > 1.5 mm / h or a cumulative settlement > 40 mm, it sends a displacement signal to the controller. The controller receives the displacement signal and feeds back a control signal to the hydraulic prop, triggering automatic pressure replenishment of hydraulic prop 2 at a rate of 8-12 kN / s, thereby increasing the support force of hydraulic prop 2. After construction is completed, the grouting reinforcement thickness is checked, and the working resistance of the hydraulic props is randomly inspected. The under-swelling amount is required to be ≤ 20 mm per month to ensure that the support effect meets the standards.

[0077] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for supporting soft rock dynamic pressure roadways using a combined support device, characterized in that, The support method includes: Step S1: Prefabricate the connector (5) and the support unit; the connector (5) includes a metal block; the support unit includes a rod-shaped hydraulic strut (2). Step S2 involves performing dual-gradient grouting on the surrounding rock of the tunnel, including: Step S2-1, shallow hole low pressure coarse-grained grouting; Step S2-2: Deep hole high-pressure fine-grain grouting; Step S3, construction of the roadway surrounding rock anchoring system; the anchoring system includes anchor bolts and anchor cables that are uniformly constructed along the radial direction of the roadway and added along the axial direction of the roadway; Step S4: Install the bearing plate (1) in the surrounding rock of the tunnel; the bearing plate (1) is a plate-shaped object, and a flat rectangular or arc-shaped bearing plate is selected according to the cross-section of the tunnel; if it is a rectangular tunnel, a flat rectangular bearing plate is selected; if it is a three-star arch tunnel, an arc-shaped bearing plate is selected. The bearing plate (1) includes a plate-shaped object, which is uniformly disposed on the tunnel wall; the first surface of the bearing plate (1) is attached to the tunnel wall; Step S5: According to the cross-sectional shape of the roadway, the connecting piece (5) and multiple support units are spliced ​​together to form a rectangular roadway joint support device or a three-star arch roadway joint support device; the first end of the hydraulic prop (2) is set on the connecting piece (5); the second end of each hydraulic prop (2) is connected to the second surface of the corresponding bearing plate (1); Step S6: Install displacement sensor (3), pressure sensor group (6) and controller; install displacement sensor (3) on the side wall of the second end of the hydraulic support (2); install pressure sensor group (6) on the end face of the hydraulic support (2) that contacts the bearing plate (1); install controller in the connector (5); Step S7, Heave construction; in severely heave areas with a heave rate > 5 mm / day, construct bottom corner grouting anchor pipes; in other heave areas, construct ordinary bottom corner anchor bolts; Step S8, dynamic support control; when the top plate sinks, the bearing plate (1) compresses the hydraulic prop (2), the displacement sensor monitors the compression of the hydraulic prop (2), sends the displacement signal to the controller, the controller receives the displacement signal and feeds back the control signal to the hydraulic prop, so that the hydraulic prop automatically replenishes fluid to the bearing plate (1) to continue to provide support force.

2. The method for supporting soft rock dynamic pressure roadways using a combined support device as described in claim 1, characterized in that, Step S2-1, shallow hole low-pressure coarse-grained grouting, includes: constructing shallow grouting holes (11) in the surrounding rock at the top of the roadway using a Φ42mm drill bit; the shallow grouting holes are 2-3m deep, 1.5-2.0m apart, arranged in a quincunx pattern, with an inclination angle of 10°-15°; the grouting material for the shallow grouting holes is: 42.5 grade ordinary Portland cement and river sand in a ratio of 1:0.5, water-cement ratio of 1:1.2, with 3% UEA expansion agent added; the grouting pressure is 0.5-1.0Mpa; grouting ends when the shallow grouting holes return grout or the grouting volume reaches the theoretical value, forming a shallow closed reinforcement ring with a thickness of 2-3m.

3. The method for supporting soft rock dynamic pressure roadways using a combined support device as described in claim 2, characterized in that, Step S2-2, deep hole high pressure fine particle grouting, includes: using a Φ56mm drill bit to construct a deep hole grouting hole (12) next to the shallow hole grouting hole (11); the deep hole grouting hole is 5-8m deep, the hole spacing is 2.5-3.0m, and it is arranged at intervals with the shallow hole, with an inclination angle of 5°-10°; the grouting material of the deep hole grouting hole is: 42.5 grade cement and silica fume mixed slurry, water-cement ratio 1:0.8, using cement-water glass double liquid slurry, volume ratio 1:0.6, water glass concentration 35Be′.

4. The method for supporting soft rock dynamic pressure roadways using a combined support device as described in claim 1, characterized in that, If the tunnel is rectangular, then select the rectangular tunnel combined support device; The rectangular roadway combined support device includes a first combined support device and a second combined support device connected by a hydraulic connecting rod (4); the second combined support device is symmetrically arranged with the first combined support device, and both include: Rigid cube connector; three support units are provided on the rigid cube; the first support unit is perpendicular to the ground; the second support unit is parallel to the ground; the third support unit is obliquely downward and at an acute angle to the second support unit; The first and second combined support devices are added along the axial direction of the rectangular roadway to form a combined support device for the rectangular roadway.

5. The method for supporting soft rock dynamic pressure roadways using a combined support device as described in claim 1, characterized in that, If it is a three-star arch tunnel, then the three-star arch tunnel combined support device shall be selected; The Samsung Arch Tunnel Joint Support Device includes Samsung Arch Tunnel Joint Support Units added along the tunnel axis; each Samsung Arch Tunnel Joint Support Unit includes: a rigid circular ring connector; five support units are arranged on the rigid circular ring connector; the first support unit is perpendicular to the ground and is located on the top of the rigid circular ring connector; the second and third support units are respectively located on both sides of the first support unit, with the second and third support units forming an angle of 50° to 75° with the first support unit; the fourth support unit is located outside the second support unit, forming an angle of 50° to 75° with the second support unit; and the fifth support unit is located outside the third support unit, forming an angle of 50° to 75° with the third support unit.

6. The method for supporting soft rock dynamic pressure roadways using a combined support device as described in claim 1, characterized in that, Step S7, bottom heave construction, includes: within the severely heaved area, constructing a bottom corner grouting anchor pipe to a depth of 3.5m at the bottom corner, injecting double-liquid grout at a pressure of 2.5MPa to form a reinforced column; the bottom corner grouting anchor pipe includes a seamless steel pipe with a diameter of Φ42mm × wall thickness of 4mm, and the length of the bottom corner grouting anchor pipe is 3.5m; grouting holes with a hole spacing of 150mm and a diameter of Φ8mm are opened at the front end of the bottom corner grouting anchor pipe, and a rubber grout stop plug is installed at the tail end of the bottom corner grouting anchor pipe.

7. The method for supporting soft rock dynamic pressure roadways using a combined support device as described in claim 1, characterized in that, Step S7, the ordinary bottom corner anchor rods used for bottom heave construction include: 2.5m long, Φ22mm, HRB400 steel anchor rods, the spacing between the steel anchor rods is 1.0m×1.2m; the shallow deformation of the bottom plate is suppressed by pre-tightening the tray.

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