A method and anchor bolt device for preventing bottom bulging of bentonite-type foundation slabs using hydrophobic anchoring.

Abstract

This invention discloses a method and anchor bolt device for preventing bottom bulging in bentonite-type foundation slabs through drainage anchoring, belonging to the field of expansive soil layer construction technology. The method includes the following steps: Step 1, water source location, identification of water-rich target areas, monitoring of hydraulic gradients, and construction of a water flow path map; Step 2, layered hole layout, optimizing the distribution of drainage holes, and layering holes according to grade; Step 3, drainage anchoring, using an anchor bolt device integrating drainage and grouting functions for targeted drainage and layered grouting, and applying prestress; Step 4, intelligent detection, including deep displacement monitoring, surface deformation monitoring, water content dynamic monitoring, and expansion stress monitoring. This invention significantly improves the stability and long-term expansion resistance of bentonite-type foundation slabs by integrating four core technologies: water source location, layered hole layout, targeted drainage anchoring, and intelligent monitoring. Simultaneously, the anchor bolt device of this invention simultaneously performs the triple functions of drainage, grouting, and prestressed anchoring.

Description

Technical Field

[0001] This invention relates to the field of expansive soil construction technology, and in particular to a method and anchor bolt device for preventing bottom bulging of bentonite-type base plates by drainage anchoring. Background Technology

[0002] Bentonite, a clay rock with montmorillonite as its core component, is characterized by its strong swelling property upon contact with water. Montmorillonite's unique layered crystal structure allows it to expand to several times or even tens of times its original volume during hydration and ion exchange, releasing enormous expansion forces. This characteristic poses a significant threat to the stability of the floor in underground engineering projects such as mine tunnels. Tunnel excavation causes stress redistribution in the floor. The bentonite strata, originally in equilibrium, develop fissures due to stress concentration. Groundwater intrudes along these fissures, causing the montmorillonite to expand continuously, generating an upward thrust. When this force exceeds the strength of the floor rock mass and the support resistance, it leads to floor bulging, cracking, and even overall uplift—a phenomenon known as floor bulging. Such damage not only reduces the tunnel cross-section and hinders transportation and ventilation, but in severe cases, it can also cause the support structure to fail, posing a significant threat to construction safety.

[0003] Currently, conventional prevention and control methods for bentonite-type floor slab heave are mainly divided into three categories: First, the drainage and pressure reduction method, which involves installing drainage holes and drainage devices to drain accumulated water from the floor slab, thereby reducing the moisture content of bentonite and weakening the expansion force. However, this method is difficult to completely drain floor slabs with complex crack development, and residual moisture can still induce slow expansion. Second, the rigid support method, which uses high-strength structures such as dense steel rails and concrete pouring to resist the heave force. However, the support structure is prone to brittle fracture due to continuous expansion force, resulting in high maintenance costs in the later stages. Third, the chemical modification method, which involves injecting modifiers such as calcium chloride into the floor slab to inhibit montmorillonite expansion. However, the modifiers are easily lost under long-term erosion by groundwater, making the effect difficult to sustain, and large-scale use may cause environmental problems.

[0004] These conventional methods generally suffer from shortcomings such as insufficient targeting, limited timeliness, or excessive cost, making it difficult to fundamentally solve the problem of continuous expansion and bulging deformation of bentonite-type base plates. Therefore, there is an urgent need to develop a comprehensive prevention and control technology that integrates hydrophobicity, reinforcement, and long-term stability control. Summary of the Invention

[0005] The purpose of this invention is to provide a method and anchor bolt device for preventing bottom bulging in bentonite-type floor slabs by drainage anchoring. This invention addresses the technical problems of determining the water source distribution and flow direction in bentonite-type floor slabs to clarify the reasonable arrangement range of drainage holes, determining the distribution of grouting holes across the bentonite-type floor slab, including parameter variations of grouting holes in areas with different water content, achieving anchoring reinforcement support for bentonite-type floor slabs in roadways to improve the overall strength of the floor slab, and monitoring the expansion and deformation of the roadway floor rock mass in bentonite-type floor slabs.

[0006] To achieve the above objectives, the present invention provides a method for preventing bottom heave of a bentonite-type base plate with hydrophobic anchoring, comprising the following steps: Step 1: Locate the water source, identify water-rich target areas and monitor hydraulic gradients, and construct a water flow path map; Step 2: Perform layered pore placement to optimize the distribution of hydrophobic pores, and place pores in layers according to grade; Step 3: Perform drainage anchoring, using an anchor bolt device with integrated drainage and grouting functions for targeted drainage and layered grouting, and apply prestress; Step 4: Conduct intelligent detection, including deep displacement monitoring, surface deformation monitoring, water content dynamic monitoring, and expansion stress monitoring.

[0007] Preferably, in step one, ground-penetrating radar and resistivity method are used to scan the bentonite-type base plate to identify low-resistivity anomaly areas as water-rich target areas; a temperature and humidity sensor network is deployed to monitor the hydraulic gradient direction, and the water flow path is constructed by combining the COMSOL inversion model; drainage holes are deployed along the main seepage direction to achieve "interception of flow through holes", and the water flow vector is verified by the difference in borehole inflow, and the hole location distribution is dynamically optimized.

[0008] Preferably, in step two, resistivity imaging and water flow vector model are combined to implement layered perforation according to risk level. In water-rich target areas, diamond-shaped dense perforation is carried out, and in low water-bearing areas, quincunx-shaped perforation is carried out to effectively block the lateral recharge path. At the same time, the coverage range is dynamically adjusted based on the difference in water inflow of the perforation group. The core is to accurately cover the three key areas of bentonite-rich layer, main seepage path and expansion deformation zone, and finally achieve the technical goal of targeted drainage.

[0009] Preferably, in step three, the holes are cleaned and filled with hydrophobic aggregate. Then, an anchor device integrating drainage and grouting functions is implanted into the bentonite-type base plate for drainage. After drainage is completed, layered targeted grouting is implemented: in the low water content area, a staggered hole pattern is used, conventional pressure grouting is performed, and a water-repellent agent is added; in the water-rich area, a diamond-shaped dense hole pattern is used, the grouting pressure is increased, and the proportion of water-repellent agent is increased. During construction, hydrophobic aggregate is laid at the bottom of the holes for drainage, and prestressing is applied to the anchor rods to ultimately achieve the dual goals of improving the overall strength of the base plate and long-term control of expansion deformation.

[0010] Preferably, in step four, deep rock mass displacement is captured in real time by embedding distributed optical fibers through boreholes; surface deformation of the bottom heave layer is monitored across the entire area using laser scanning of the top plate; the dynamic water content of bentonite is detected by array capacitive sensors, which sense water migration in layers; the expansion stress of bentonite is monitored by embedding grating pressure gauges at the anchor bolt interface; the early warning mechanism integrates microseismic positioning and a digital twin platform, which automatically triggers the prevention and control system when the water content increases significantly or the strain rate is fast, thereby achieving precise control of the deformation source.

[0011] An anchor bolt device includes an anchor bolt body, the anchor bolt body including a drainage pipe and a grouting pipe, the drainage pipe being disposed in the middle of the anchor bolt body, the grouting pipe being evenly arranged around the drainage pipe in the circumferential direction, and a plurality of grouting holes being spirally spaced on the outer wall of the anchor bolt body, the grouting holes being connected to the grouting pipes; An anchor head is fixedly connected to the bottom of the anchor body. The anchor head is in the shape of an inverted frustum, and lateral spray holes are evenly arranged on the arc surface of the anchor head. The anchor head has a bottom grouting hole along the vertical direction. The bottom grouting hole and the lateral spray holes are both connected to the grouting pipe. The middle of the anchor head has a bottom drainage hole along the vertical direction. The bottom drainage hole is connected to the drainage pipe. The bottom grouting hole is evenly arranged around the outer periphery of the bottom drainage hole.

[0012] Preferably, a nano-hydrophobic filter is embedded in the grouting hole, and a superhydrophobic copper mesh is provided inside the hydrophobic tube.

[0013] Preferably, both the grouting pipe and the drainage pipe are provided with tail interfaces, which include a water pump interface and a grouting pump interface. The water pump is connected to the water pump interface on the drainage pipe through a water supply pipe. The end of the water supply pipe is connected to a drainage ditch. The grouting machine is connected to the grouting pump interface on the grouting pipe through a grout supply pipe.

[0014] Preferably, a pad is inserted through the tail of the anchor bolt body, and the pad is located on the inner wall of the tunnel.

[0015] Preferably, a plurality of fiber optic pressure gauges are fixedly connected to the top of the anchor head along the circumferential direction.

[0016] The advantages and positive effects of the method and anchor bolt device for preventing bottom bulging of bentonite-type base plates described in this invention are as follows: 1. The present invention provides a method for preventing bottom bulging of bentonite-type base plates by integrating four core technologies: water source positioning, layered hole layout, targeted drainage and anchoring, and intelligent monitoring. This method significantly improves the stability and long-term anti-swelling ability of bentonite-type base plates.

[0017] 2. The anchor bolt device of this invention simultaneously performs three functions: drainage, grouting, and prestressed anchoring. For anti-clogging and drainage, it is equipped with a nano-hydrophobic filter screen and a superhydrophobic copper mesh for water guidance. Furthermore, the lateral spray holes in the anchor head design allow the grout to diffuse like tree roots, enhancing the reinforcement effect. The spirally spaced grouting holes on the anchor bolt facilitate radial diffusion of the grout.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a simplified flowchart of a method for preventing bottom bulging of a bentonite-type base plate according to the present invention. Figure 2 This is a detailed flowchart of a method for preventing bottom bulging in a bentonite-type base plate according to the present invention. Figure 3 This is a schematic diagram of the structure of the anchor bolt body of the present invention; Figure 4 for Figure 3 Sectional view along axis AA; Figure 5 for Figure 3 BB-direction sectional view; Figure 6 This is a schematic diagram of the bottom of the anchor head of the present invention; Figure 7 This is a diagram showing the usage state of the anchor bolt body of the present invention.

[0020] Figure Labels 1. Anchor bolt body; 2. Grouting hole; 3. Drainage pipe; 4. Superhydrophobic copper mesh; 5. Anchor head; 6. Tail end interface; 7. Pad plate; 8. Grating pressure gauge; 9. Water pump interface; 10. Grouting pump interface; 11. Drainage hole at the bottom of the anchor head; 12. Grouting hole at the bottom of the anchor head; 13. Grouting pipe; 14. Drainage ditch; 15. Water pump; 16. Grouting machine; 17. Tunnel; 18. Water delivery pipeline; 19. Grout delivery pipeline; 20. Lateral spray hole. Detailed Implementation

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the 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 the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] In this application, 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 application pertains. In case of any inconsistency, the meaning set forth in this specification or derived from the content described herein shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit the scope of this application.

[0023] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] like Figures 1-7 As shown, a method for preventing bottom heave caused by hydrophobic anchoring in bentonite-type foundation slabs includes the following steps: Step 1: Locate the water source, identify water-rich target areas and monitor hydraulic gradients, and construct a water flow path map; Step 2: Perform layered pore placement to optimize the distribution of hydrophobic pores, and place pores in layers according to grade; Step 3: Perform drainage anchoring, using an anchor bolt device with integrated drainage and grouting functions for targeted drainage and layered grouting, and apply prestress; Step 4: Conduct intelligent detection, including deep displacement monitoring, surface deformation monitoring, water content dynamic monitoring, and expansion stress monitoring.

[0025] In step one, ground-penetrating radar and resistivity method are used to scan the bentonite-type base plate and identify low-resistivity anomaly areas as water-rich target areas; a network of temperature and humidity sensors is deployed to monitor the hydraulic gradient direction, and the water flow path is constructed by combining the COMSOL inversion model; drainage holes are deployed along the main seepage direction to achieve "interception of flow through holes", and the water flow vector is verified by the difference in borehole inflow, and the hole location distribution is dynamically optimized.

[0026] In step two, resistivity imaging and water flow vector model are combined to implement layered perforation according to risk level. In water-rich target areas, diamond-shaped dense perforation is carried out, and in low water-bearing areas, quincunx-shaped perforation is carried out to effectively block the lateral recharge path. At the same time, the coverage range is dynamically adjusted based on the difference in water inflow of the perforation group. The core is to accurately cover the three key areas of bentonite-rich layer, main seepage path and expansion deformation zone, and finally achieve the technical goal of targeted drainage.

[0027] In step three, the holes are cleaned and filled with hydrophobic aggregate. Then, an anchor bolt device integrating drainage and grouting functions is implanted into the bentonite-type base plate for drainage. After drainage is completed, layered targeted grouting is implemented: in the low water content area, a staggered hole pattern is used, conventional pressure grouting is performed, and a water-repellent agent is added; in the water-rich area, a diamond-shaped dense hole pattern is used, the grouting pressure is increased, and the proportion of water-repellent agent is increased. During construction, hydrophobic aggregate is laid at the bottom of the holes for drainage, and prestressing is applied to the anchor bolts to ultimately achieve the dual goals of improving the overall strength of the base plate and long-term control of expansion deformation.

[0028] In step four, deep rock mass displacement is monitored by embedding distributed optical fibers in boreholes to capture rock mass strain in real time; surface deformation of the bulging layer is monitored using top plate laser scanning to measure the bulging volume across the entire area. Bentonite moisture dynamics are detected using array capacitive sensors to sense moisture migration in layers. Bentonite expansion stress is assessed by embedding grating pressure gauges at the anchor bolt interface. The early warning mechanism integrates microseismic positioning and a digital twin platform; when there is a significant increase in moisture content or a rapid strain rate, the prevention and control system is automatically triggered, achieving precise control of the deformation source.

[0029] Example 1 A method for preventing bottom heave in bentonite-type foundations using hydrophobic anchoring is proposed. Step one involves geological conditions with a montmorillonite content of 38%, well-developed fissures, an initial water content of 26.7%, and a bottom heave rate of 12 mm / month. First, the water source is precisely located using geophysical scanning. A 250MHz ground-penetrating radar is used to detect water-rich fissure zones (resistivity 8Ω・m-15Ω・m), and the area of ​​the main water-rich zone is determined using resistivity imaging. In the water flow inversion stage, temperature and humidity sensors are deployed to monitor the hydraulic gradient, and the peak water flow velocity along the fault is further displayed using a COMSOL model. Based on this, hydrophobic holes are drilled with an inclination angle of 8° and a diameter of 60 mm.

[0030] The formula for verifying the inflow rate is as follows: Q 顺流 To the direction of the inflow, Q 垂直 This refers to the vertical flow rate.

[0031] Step two: Combining resistivity imaging and water flow vector modeling, areas with resistivity less than 20 Ω·m are designated as high-risk zones. Layered borehole layout is implemented according to risk level: For high-risk zones composed of water-rich bentonite zones, a denser rhomboid grid of 0.8m × 0.8m is used, with borehole depths reaching 3m to penetrate the expansion layer. In the diffusion zone, a 1.2m × 1.2m quincunx-shaped borehole group is laid out, with a borehole depth controlled at 2.8m to form a three-dimensional seepage interception network.

[0032] Step 3: After cleaning the borehole, fill it with drainage aggregate, which is a mixture of volcanic rock slag and rubber particles in a 7:3 ratio, with a porosity of 48%. Then, use an anchor bolt device with integrated drainage and grouting functions to be installed in the bottom plate of the expansive soil layer. The borehole radius is 0.03m. Connect the tail interface 6 to a water pump and use the drainage function of the anchor bolt to drain the water accumulated at the bottom. Then, perform layered grouting.

[0033] In the low-moisture diffusion zone, the main component of this grouting material is epoxy resin, accounting for 65.8%. The curing agent is polyamide, accounting for 16.5%. The water-repellent agent is silane coupling agent, accounting for 4.1%. The additive is 0.5mm-1mm expanded perlite, accounting for 13.6%.

[0034] The main component of the grouting material for water-rich areas is modified epoxy resin, accounting for 61.3%. Modified amine curing agent accounts for 17.2%. Water-repellent agent accounts for 5.2%. Toughening aggregate is 1mm-3mm rubber particles, accounting for 15.3%. Expansion compensator is ettringite powder, accounting for 0.9%.

[0035] In the low water-content diffusion zone, , , .

[0036] P 低 C is the grouting pressure in the diffusion zone. h1 The concentration of hydrophobic agent in the diffusion zone (%), V g Aggregate filler volume (m) 3 ), This refers to the water content.

[0037] In the water-rich area, , , .

[0038] P 高 For the grouting pressure in the water-rich area, C h2 The concentration of water-repellent agent in water-rich areas (%), V g Aggregate filler volume (m) 3 ), This refers to the water content.

[0039] During the curing stage, it is necessary to wait for the grout in the anchoring section to reach the strength required by the design, which usually takes several days. After the strength of the grout in the anchoring section meets the requirements, the tensioning and locking stage begins. The anchor rod is tensioned, and after the design prestress is applied, it is locked to the anchor block or girder.

[0040] The prestressing formula is: H represents a burial depth of 550m. The expansion stress is taken as 3.1 MPa, and F is 75 kN.

[0041] Step four: Deep displacement is performed using distributed optical fibers, deployed vertically via drilling. The drilling depth is three times the thickness of the bottom drum layer, with a spacing of 15 meters between holes. Data acquisition frequency is 1 time per minute. Surface deformation is measured using a top-mounted laser scanner, deployed every 30 meters with a scanning radius of 50 meters and an accuracy of 0. Point cloud density is The sampling frequency is once per hour. Moisture content is monitored using an array of capacitive sensors, which are installed in layers along the borehole with a vertical spacing of 0.5 meters. The monitoring accuracy is ±0.5%, the range is 0-40%, and the sampling frequency is once every five minutes. Expansion stress is monitored using fiber optic grating pressure gauges, which are arranged in a ring at the anchor-surrounding rock interface, with three measuring points per anchor. The accuracy is 0.01 MPa, the range is 0-10 MPa, and the sampling frequency is once per second. Microseismic events are monitored by a 16-channel ESG microseismic system, staggered between the top and bottom plates with a spacing of 20 meters. The positioning error is ≤0.5 meters, and continuous monitoring mode is used.

[0042] An anchor bolt device includes an anchor bolt body 1, which includes a drainage pipe 3 and a grouting pipe 2. The drainage pipe 3 is located in the middle of the anchor bolt body 1, and the grouting pipes 2 are evenly arranged around the drainage pipe 3 in a circumferential direction. Multiple grouting holes 2 are spirally spaced on the outer wall of the anchor bolt body 1, and the grouting holes 2 are connected to the grouting pipes 13. An anchor head 5 has a bottom grouting hole 12 arranged vertically, and the bottom grouting hole 12 is connected to the grouting pipe 13.

[0043] Specifically, multiple grouting holes 2 arranged in a spiral pattern enable the grout to diffuse radially.

[0044] An anchor head 5 is fixedly connected to the bottom of the anchor body 1. The anchor head 5 is in the shape of an inverted frustum, and lateral spray holes 20 are evenly arranged on the arc surface of the anchor head 5.

[0045] Anchor head 5 has a grouting hole 12 at the bottom of the anchor head along the vertical direction. The grouting hole 12 at the bottom of the anchor head and the side spray hole are connected to the grouting pipe 13, which can realize the diffusion of grout in a root-like manner, thereby improving the reinforcement effect. A drainage hole 11 at the bottom of the anchor head 5 is provided in the middle of the anchor head along the vertical direction. The drainage hole 11 at the bottom of the anchor head is connected to the drainage pipe 3. The grouting holes 12 at the bottom of the anchor head are evenly distributed around the outer periphery of the drainage hole 11 at the bottom of the anchor head.

[0046] The grouting hole 2 is embedded with a nano-hydrophobic filter, and the hydrophobic tube 3 is equipped with a superhydrophobic copper mesh.

[0047] Specifically, the nano-hydrophobic filter can effectively prevent clogging, and the superhydrophobic copper mesh has a porosity of 92%, which facilitates the drainage of water accumulated in the bentonite-type base plate.

[0048] Both the grouting pipe and the drainage pipe 3 are equipped with a tail interface 6. The tail interface 6 includes a water pump interface 9 and a grouting pump interface 10. The water pump 15 is connected to the water pump interface 9 on the drainage pipe 3 through the water supply pipe 18. The end of the water supply pipe 18 is connected to the drainage ditch 14. The grouting machine 16 is connected to the grouting pump interface on the grouting pipe 13 through the grout supply pipe 19.

[0049] A pad 7 is inserted through the tail of the anchor bolt body 1, and the pad 7 is located on the inner wall of the tunnel 17. Multiple fiber optic pressure gauges are fixedly connected to the top of the anchor head 5 along the circumferential direction.

[0050] The method of using the anchor bolt device is as follows: First, the anchor bolt device is placed inside the borehole, and the tail of the anchor bolt body 1 is set on the inner wall of the roadway 17 through the pad plate 7 to ensure the stability of the anchor bolt and prevent displacement during grouting.

[0051] Secondly, the water pump 15 is connected to the water pump interface 9 on the drainage pipe 3 through the water supply pipe 18, and uses the drainage function of the anchor rod to drain the water accumulated at the bottom.

[0052] Then, the grouting machine 16 is connected to the grouting pump interface 10 on the grouting pipe 13 through the grouting pipeline 19, and then layered grouting is carried out.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preventing bottom heave caused by hydrophobic anchoring in bentonite-type foundation slabs, characterized in that: Includes the following steps, Step 1: Locate the water source, identify water-rich target areas and monitor hydraulic gradients, and construct a water flow path map; Step 2: Perform layered pore placement to optimize the distribution of hydrophobic pores, and place pores in layers according to grade; Step 3: Perform drainage anchoring, using an anchor bolt device with integrated drainage and grouting functions for targeted drainage and layered grouting, and apply prestress; Step 4: Conduct intelligent detection, including deep displacement monitoring, surface deformation monitoring, water content dynamic monitoring, and expansion stress monitoring; In step one, ground-penetrating radar and resistivity method are used to scan the bentonite-type base plate and identify low-resistivity anomaly areas as water-rich target areas. A network of temperature and humidity sensors is deployed to monitor the direction of the hydraulic gradient, and the water flow path is constructed by combining it with the COMSOL inversion model. Drainage holes are arranged along the main permeation direction to achieve "interception of flow through holes", and the water flow vector is verified by the difference in water inflow from the boreholes to dynamically optimize the hole location distribution; In step two, resistivity imaging and water flow vector model are combined to implement layered hole layout according to risk level. In water-rich target areas, diamond-shaped dense hole layout is carried out, and in low water-bearing areas, quincunx-shaped hole layout is carried out to effectively block the lateral recharge path. At the same time, the coverage range is dynamically adjusted based on the difference in water inflow of the hole group. The core is to accurately cover the three key areas of bentonite-rich layer, main seepage path and expansion deformation zone, and finally achieve the technical goal of targeted drainage. In step three, the holes are cleaned and filled with hydrophobic aggregate. Then, an anchor bolt device integrating drainage and grouting functions is implanted into the bentonite-type base plate for drainage. After drainage is completed, layered targeted grouting is implemented: in the low water content area, a staggered hole pattern is used, conventional pressure grouting is performed, and a water-repellent agent is added; in the water-rich area, a diamond-shaped dense hole pattern is used, the grouting pressure is increased, and the proportion of water-repellent agent is increased. During construction, hydrophobic aggregate is laid at the bottom of the holes for flow guidance, and prestressing is applied to the anchor bolts to ultimately achieve the dual goals of improving the overall strength of the base plate and long-term control of expansion deformation. In step four, deep rock mass displacement is monitored by embedding distributed optical fibers in boreholes to capture rock mass strain in real time; surface deformation of the bottom heave layer is monitored by laser scanning of the top plate to monitor the bottom heave amount across the entire area; the dynamic water content of bentonite is monitored by array capacitive sensors to sense water migration in layers; the expansion stress of bentonite is monitored by embedding grating pressure gauges at the anchor bolt interface; the early warning mechanism integrates microseismic positioning and a digital twin platform, and automatically triggers the prevention and control system when the water content increases significantly or the strain rate is fast, so as to achieve precise control of the deformation source. The anchor bolt device includes an anchor bolt body, which includes a drainage pipe and a grouting pipe. The drainage pipe is located in the middle of the anchor bolt body, and the grouting pipes are evenly arranged around the drainage pipes in the circumferential direction. Multiple grouting holes are spirally spaced on the outer wall of the anchor bolt body, and the grouting holes are connected to the grouting pipes. An anchor head is fixedly connected to the bottom of the anchor bolt body. The anchor head is in the shape of an inverted frustum, and lateral spray holes are evenly arranged on the arc surface of the anchor head. The anchor head has a bottom grouting hole in the vertical direction. The bottom grouting hole and the lateral spray holes are both connected to the grouting pipe. The middle of the anchor head has a bottom drainage hole in the vertical direction. The bottom drainage hole is connected to the drainage pipe. The bottom grouting hole is evenly arranged around the outer periphery of the bottom drainage hole. The grouting hole is embedded with a nano-hydrophobic filter screen, and the hydrophobic tube is equipped with a superhydrophobic copper mesh. Multiple fiber optic pressure gauges are fixedly connected to the top of the anchor head along the circumferential direction.

2. The method for preventing bottom bulging of a bentonite-type base plate with hydrophobic anchoring according to claim 1, characterized in that: Both the grouting pipe and the drainage pipe are provided with tail interfaces, which include a water pump interface and a grouting pump interface. The water pump is connected to the water pump interface on the drainage pipe through a water supply pipe. The end of the water supply pipe is connected to the drainage ditch. The grouting machine is connected to the grouting pump interface on the grouting pipe through a grout supply pipe.

3. The method for preventing bottom heave of a bentonite-type base plate with hydrophobic anchoring according to claim 2, characterized in that: The tail of the anchor bolt body is penetrated by a pad, which is located on the inner wall of the tunnel.

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