Soft rock large deformation control method and rapid supporting system suitable for TBM tunnel construction method characteristics

Abstract

The invention discloses a soft rock large deformation control method and a rapid support system suitable for TBM tunnel construction method characteristics, the method is implemented based on an anchoring support system composed of a short anchoring support system and a long anchoring support system, and the method is suitable for an open TBM construction scene: in a TBM tunneling process, before a shield is exposed, the shield is not exposed, and the long anchoring support system is not exposed; a short anchoring support system of a full-length anchoring anchor rod structure is timely arranged in the radial direction of the 180-degree area of the upper half ring of the tunnel section through a cutter head edge cutter hole, and the short anchoring support system and a shield cooperate to form an initial deformation control system; after the shield is exposed, according to the deformation degree of the surrounding rock, full-length anchoring anchor rods or pre-stressed anchor cables are adopted in a graded mode, long anchoring supporting systems are arranged at intervals with the short anchoring supporting systems in a spiral mode, then the long anchoring supporting systems are cooperatively borne with steel arches, reinforcing meshes and sprayed concrete, and the long anchoring supporting systems are matched with 70m system sprayed concrete and 1000m secondary lining construction behind a tunnel face. According to the method, the displacement around the hole is effectively controlled, the TBM is prevented from being stuck, and the construction safety and efficiency of the open-type TBM in the soft rock large-deformation geology are improved.

Description

Technical Field

[0001] This invention relates to the field of TBM tunnel support technology, specifically to a method for controlling large deformations in soft rock and a rapid support system suitable for the characteristics of TBM tunnel construction. Background Technology

[0002] The underground engineering anchoring system mainly consists of full-length anchor bolts and prestressed anchor cables. It strengthens the rock mass by limiting the deformation of the surrounding rock and has been widely used in tunnels and underground engineering, slope and foundation pit excavation and other scenarios. It is also a core component of shotcrete support in tunnel excavation methods such as TBM and drill-and-blast method.

[0003] Although TBMs (tunnel boring machines) are primarily used for hard rock tunnel excavation, in actual construction, they inevitably traverse complex geological areas such as fault fracture zones. In these areas, the surrounding rock conditions change drastically along the tunnel's longitudinal direction, easily causing problems such as TBM shield jamming, which affect the construction progress. Existing TBM anchoring support systems have significant limitations, only allowing for anchor bolt and cable installation after the shield has emerged, making it difficult to effectively control the large deformations in soft rock caused by traversing fault fracture zones. Summary of the Invention

[0004] In response to the aforementioned technical problems, this application solves the technical issues existing in the construction of TBM tunnels, such as delayed support, difficulty in fully utilizing the inherent self-supporting capacity of the surrounding rock, high construction risks, and high construction costs.

[0005] To achieve the above objectives, the technical solution adopted in this application is: a method for controlling large deformation in soft rock and a rapid support system suitable for the characteristics of TBM tunnel construction. This control method is based on an anchored support system, which consists of a short anchored support system and a long anchored support system. The control method includes the following steps: during TBM excavation, before the shield is exposed, the short anchored support system is installed radially around the tunnel circumference in a timely manner; after the TBM shield is exposed, it is reinforced by the long anchored support system. The two work together to form the anchored support system for rapid and active control of large deformation in the TBM tunnel. The control method and the anchored support system are applicable to the construction scenario of open-face TBMs.

[0006] To better realize the present invention, the installation and support method of the short anchor support system is as follows: installation is carried out radially perpendicular to the rock surface, the installation time corresponds to before the shield is exposed, and the installation range is limited to the 180-degree area of ​​the upper half ring on the tunnel cross section.

[0007] To better realize the present invention, the short anchoring support system further adopts a full-length anchoring bolt structure.

[0008] To better realize the present invention, the short anchor support system forms a surrounding rock deformation control system inside the shield after timely support, including: using the effective restriction effect of the TBM shield on the surrounding rock, and realizing rapid construction and initial deformation control through the timely installation of the short anchor support system.

[0009] To better realize the present invention, the support method of the long anchoring system after the TBM shield is exposed is as follows: when the surrounding rock deformation is small, the long anchoring system adopts full-length anchoring bolts to effectively control the shape by coordinating deformation with the surrounding rock; when the surrounding rock deformation is large, the long anchoring system adopts prestressed anchor cables to actively control the deformation of the surrounding rock to ensure the support effect.

[0010] To better realize the present invention, the long anchoring system is further constructed using TBM construction technology and is installed in a spiral manner.

[0011] To better realize the present invention, the long anchoring system and the short anchoring system are arranged in an alternating manner: along the tunnel excavation direction, a long anchoring support system is set in the middle position of two adjacent rows of short anchoring support systems, and the two work together to form a complete anchoring support system.

[0012] To better realize the present invention, the short anchorage support system is further installed radially along the tunnel through the side cutter holes of the TBM cutterhead.

[0013] To better realize the present invention, the long anchorage support system, together with the steel arch support, steel mesh, and emergency shotcrete operation, jointly bears the surrounding rock load.

[0014] To better realize the present invention, furthermore, a system of shotcrete support is carried out about 70m behind the working face, and secondary lining construction is carried out 1000m behind the working face.

[0015] The technical solution provided by this invention has the following advantages compared with the prior art: 1. In this invention, before the TBM shield is exposed, a short-anchored support system is promptly installed along the 180-degree half-ring area of ​​the tunnel cross-section; this rapidly supports the loose surrounding rock at the excavation face; it preemptively constrains the initial deformation of the surrounding rock, stimulating its inherent self-supporting capacity; it effectively reduces the displacement around the tunnel and the range of the plastic zone near the TBM cutterhead, minimizing the adverse effects of surrounding rock deformation on construction. The short-anchored support system is installed radially along the tunnel through the side cutter holes of the TBM cutterhead; this simplifies the construction operation process; it eliminates the need for additional installation channels, adapting to TBM construction conditions; the construction process is convenient and easy to operate, improving support timeliness and reducing construction complexity.

[0016] 2. In this invention, the short-anchored support system works synergistically with the TBM shield to form a surrounding rock deformation control system within the shield. This system jointly restricts surrounding rock deformation and shares the surrounding rock load, reducing the load-sharing ratio of the TBM shield and effectively preventing accidents such as TBM jamming, thus ensuring construction continuity. After the TBM shield is exposed, the type of long-anchored support system is selected based on the degree of surrounding rock deformation (full-length anchor bolts are used for smaller deformations, and prestressed anchor cables are used for larger deformations). This allows for targeted control of later-stage surrounding rock deformation, adapting to different geological deformation conditions and achieving a combination of active shape control and synergistic deformation. This ensures stable and reliable support performance and avoids support failure due to differences in deformation levels.

[0017] 3. In this invention, the long anchorage support system is installed in a spiral pattern based on TBM construction technology; it adapts to the TBM construction process; optimizes the compatibility between the anchorage system and TBM excavation, improving installation efficiency; avoids mutual interference between support operations and TBM construction, ensuring construction progress. The long anchorage support system and the short anchorage support system are arranged alternately along the tunnel excavation direction (a long anchorage support system is placed between two adjacent rows of short anchorage support systems); constructing a complete anchorage support system; achieving full longitudinal coverage support of the tunnel, forming a collaborative force-bearing mechanism; comprehensively limiting the deformation of the surrounding rock at each stage, improving the integrity and stability of the support system. The short anchorage support system adopts a full-length anchorage bolt structure; enhancing the initial support strength; tightly integrating with the surrounding rock, quickly exerting its anchoring effect; shortening the initial support response time, effectively inhibiting the loosening and diffusion of the surrounding rock, laying the foundation for later support.

[0018] 4. In this invention, the anchoring support system and control method are applicable to open-face TBM construction scenarios; adaptable to specific TBM construction types; specifically solves the support challenges of open-face TBMs in soft rock with large deformation geology; expands the applicable geological range of open-face TBMs and improves their construction adaptability under complex geological conditions. The long anchoring support system, together with steel arch support, steel mesh, and emergency shotcrete operations, collaboratively bears the surrounding rock load; forms a multi-support collaborative mechanism; disperses the surrounding rock load, improving the overall support bearing capacity; enhances the deformation resistance of the support system, reduces the stress on individual support structures, and improves construction safety. Systematic shotcrete support is carried out approximately 70m after the tunnel face, and secondary lining construction is carried out 1000m after the tunnel face; the support sequence and process connection are optimized; the support effect is strengthened in stages to ensure the long-term stability of the tunnel; balancing construction efficiency and support reliability, avoiding potential deformation hazards caused by unreasonable support sequence, and reducing engineering maintenance costs. Attached Figure Description

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

[0020] Figure 1 This is a schematic diagram of the method steps in an embodiment of the present invention; Figure 2 This is a schematic cross-sectional view of the long anchorage support system according to an embodiment of the present invention; Figure 3 This is a schematic cross-sectional view of the short anchorage support system according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the longitudinal section of the anchoring support system of the present invention; Figure 5 This is a schematic diagram showing the installation location of the short anchorage support system according to an embodiment of the present invention; Explanation of reference numerals in the attached figures: 1-Long anchorage support system; 2-Short anchorage support system; 3-TBM shield shell; 4-Short anchorage support system installation location (i.e., TBM cutterhead edge cutter hole). Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this application, it should be noted that the use of terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These terms are used solely for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the use of terms such as "first" and "second" in the description of this application is only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this application does not imply that the component is required to be absolutely horizontal or suspended, but rather that it may be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0026] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" 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 connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] Example 1 Please refer to the attached document. Figure 1 The diagram below is a flowchart of an embodiment of the present invention. Further, a method for controlling large deformations in soft rock and a rapid support system suitable for the characteristics of TBM tunnel construction can include the steps described in steps S1-S4: S1: During the TBM tunneling process, before the shield shell is exposed, a circumferential short anchor support system is installed in a timely manner along the radial direction of the cutter hole on the side of the TBM cutterhead. The installation range is the 180-degree range of the upper half ring on the tunnel cross-section. S2: The short anchoring support system, together with the shield shell, restricts the deformation of the surrounding rock, forming a surrounding rock deformation control system inside the shield shell; S3: After the shield shell is exposed, long anchor support systems are installed along the short anchor support system intervals in the longitudinal direction of the tunnel, which work together with steel arch support, system shotcrete, steel mesh and other load-bearing structures. S4: The long anchorage support system and the short anchorage support system work together to limit the deformation of the surrounding rock in the later stage of excavation.

[0028] In practice, it has been found that the main problems with existing engineering measures for handling large deformations caused by TBMs crossing fault fracture zones are: Firstly, under the existing TBM excavation method, anchor bolts or cables, steel arch supports, and shotcrete system support can only be installed after the TBM shield is exposed. Therefore, near the excavation face, only the TBM shield and TBM cutterhead can effectively support the surrounding rock, limiting the deformation of the face and the surrounding rock behind it, resulting in insufficient effective support.

[0029] Secondly, based on the concept of drill-and-blast pre-support, pipe roof support and pre-sinking grouting with small guide pipes have been increasingly used in TBM tunnels to improve the mechanical conditions of the surrounding rock ahead of the tunnel face and reduce the risk of TBM jamming. However, these methods are difficult to implement, and the large volume of grouting increases construction costs and significantly impacts the project schedule. Therefore, there is an urgent need for a convenient and cost-effective method for controlling deformation and anchoring support when TBMs traverse fault fracture zones.

[0030] In this embodiment, in step S1, the main materials of the short anchorage support system can be determined according to the site requirements. The selection of materials should be based on factors such as the geological conditions of the tunnel site and the main equipment required for anchor bolt construction, and should be determined with reference to the specifications.

[0031] For example, when selecting materials for short anchorage support systems, refer to the anchor design clauses in Article 5.3 of the "Q-CR9248-2020 Technical Specification for Anchor Support in Railway Tunnels".

[0032] For example, when determining the layout of the short anchorage support system, the layout position is determined according to the side cutter holes of the TBM cutterhead, and the short anchorage system is installed through the side cutter holes. The layout range of the short anchorage support system is within 180 degrees of the upper half ring on the tunnel cross-section.

[0033] In this embodiment, the effective range of the surrounding rock deformation control system formed by the shield shell and the short anchor support system in step S2 is the effective length of the shield shell. In this embodiment, the timely installation of the short anchor support system can effectively reduce the proportion of surrounding rock load on the shield shell, while giving full play to the inherent self-supporting capacity of the surrounding rock. Compared with the case without the installation of the short anchor support system, this embodiment effectively reduces the degree of surrounding rock deformation and reduces the risk of TBM jamming to a certain extent.

[0034] In this embodiment, the long anchoring support system described in step S3 is determined based on the degree of surrounding rock deformation. When the surrounding rock deformation is small, full-length anchor bolts are used to deform in tandem with the surrounding rock, achieving reinforcement. When the surrounding rock deformation is large, the long anchoring support system described in step S3 should use prestressed anchor cables to actively control the surrounding rock deformation.

[0035] For example, when determining the materials for a long anchorage support system, refer to Section 4 of the "Q-CR9248-2020 Technical Specification for Anchor Support in Railway Tunnels" regarding anchor bolts (cables) and anchorage materials.

[0036] In this embodiment, the installation method of the long anchorage support system described in step S3 is based on the TBM anchorage system installation method, which is arranged in a spiral pattern along the tunnel cross section. Please refer to the appendix. Figure 2 Along the longitudinal direction of the tunnel, short anchorage support systems are installed at intervals; please refer to the appendix. Figure 4 .

[0037] In the comparative examples of this application, Case 1 is defined as timely support using a 3m short anchorage support system, Case 2 as timely support using a 4m short anchorage support system, and Case 3 as timely support without using a short anchorage support system. In all three cases, the length of the long anchorage support system is 8m. The deformation control of the surrounding rock when the TBM tunnel crosses a fault is compared under different conditions to verify the effectiveness of the invention. Please refer to the appendix. Figure 1-5 Please refer to the following examples: The implementation process of the example is as follows: 1) Parameter selection for short-anchored support system and long-anchored support system The mechanical properties of anchor bolts are determined by geometric parameters, anchor bolt material parameters, and the properties of cement grout. The properties of the cement grout include the outer circumference of the cement grout and the bond strength per unit length. Referring to Tables C.0.5-1 and C.0.5-3 of the "Technical Specification for Anchor Bolt Support in Railway Tunnels" (Q / CR9248-2020), the physical and mechanical parameters of the anchor bolts were set as shown in Table 1 during the implementation of this example.

[0038] Table 1. Physical and mechanical parameters of the anchoring support system in the embodiments. ; The soil layer model parameters in the embodiments are shown in Table 2: Table 2. Soil layer model parameter table in the embodiments. 2) ; 3) Layout of short anchorage support system During TBM excavation, short anchored support systems 2 are installed radially along the cutterhead side holes 4 of the TBM cutterhead. These short anchored support systems 2 and the TBM shield shell 3 work together to bear the load, forming a deformation control system for the surrounding rock within the shield shell. The short anchored support system 2 is installed within a 180-degree radius of the half-ring on the tunnel cross-section, with its length distinguished by working conditions 1, 2, and 3. Along the longitudinal direction of the tunnel, the interval between the short anchored support systems 2 is 0.9m.

[0039] 3) Layout of long anchorage support system After the TBM shield emerges, based on the TBM construction method, full-length anchor bolts 1 are installed in a spiral pattern on the tunnel cross-section, with a bolt length of 8m for all three working conditions. Along the longitudinal direction of the tunnel, the long anchor support system 1 is spaced 0.9m apart, interspersed with the short anchor support system 2. Simultaneously, in all three working conditions, steel supports, steel mesh, and emergency shotcrete are installed after the shield emerges. System shotcrete support is carried out 70m behind the tunnel face, and secondary lining construction is carried out 1000m behind the tunnel face.

[0040] 4) Comparison of results from the examples Taking the tunnel face displacement under three working conditions as an example, the implementation results are summarized in Table 3. The working condition description is "Working Condition Number - Tunnel Longitudinal Monitoring Point Location - Vertical / Horizontal Tunnel Displacement". The mileage of the TBM tunnel crossing the fault fracture zone is 60m to 110m. The longitudinal monitoring point locations within the fault fracture zone are 62m, 85m, and 107m. The monitoring points at 62m and 107m are located at the entry and exit points of the fault fracture zone, respectively. Therefore, comparing the displacement at these two monitoring point locations is more effective, highlighting the method of rapid and active control of large deformation in TBM tunnels and the role of the anchor support system.

[0041] Table 3. Displacement of the tunnel face around the tunnel at various working conditions. ; The table above shows the deformation around the tunnel when the excavation face reaches the following: Under condition 2, the vertical deformation at 25m is 6.13mm and the horizontal deformation is 14.7mm, which is not significantly different from condition 1; Under condition 2, the vertical deformation at 62m is 9.55mm and the horizontal deformation is 23.7mm. Compared with condition 1, the vertical displacement around the tunnel when the excavation face reaches the tunnel decreases by 4.8%, and the horizontal displacement around the tunnel decreases by 5.2%; Under condition 2, the vertical deformation at 85m is 13.3mm and the horizontal deformation is 31.3mm. Compared with condition 1, the vertical displacement around the tunnel decreased by 7.5% when the excavation face was reached, and the horizontal displacement around the tunnel decreased by 3.1% when the excavation face was reached. Under condition 2, the vertical deformation at 107m was 8.49mm and the horizontal deformation was 25.1mm. Compared with condition 1, the vertical displacement around the tunnel decreased by 3.1% when the excavation face was reached, and the horizontal displacement around the tunnel decreased by 5.3% when the excavation face was reached. Under condition 2, the vertical deformation at 150m was 7.64mm and the horizontal deformation was 13.2mm, which was not much different from the displacement under condition 1.

[0042] Compared with the calculation results for without timely circumferential anchor support (condition 3), the displacement around the tunnel when timely circumferential anchor support is used to cross the fault fracture zone section is significantly reduced. Without timely circumferential anchor support (condition 3), the maximum vertical deformation around the tunnel when the excavation face arrives is 20mm, and the maximum horizontal deformation is 40mm. When timely support is provided using 4m circumferential anchors (condition 1), the maximum vertical deformation when the excavation face arrives is 13.3mm, and the maximum horizontal deformation is 31.3mm, representing reductions of 27.3% and 15.4%, respectively.

[0043] By comparing the tunnel perimeter deformation under the three working conditions described above, this embodiment demonstrates that by promptly implementing a short-anchor support system to support the surrounding rock at the tunnel face, and by having the short-anchor support system share the load with the TBM shield, the load-sharing ratio of the shield is reduced, effectively leveraging the inherent self-supporting capacity of the surrounding rock, and mitigating the risk of TBM jamming to a certain extent. Compared with advanced support methods such as pipe roof support and advanced small-diameter pipe grouting, this embodiment has lower construction difficulty and reduces construction costs, making it easy to apply directly in engineering practice.

[0044] Based on the above description of the present invention, the specific details are as follows: Firstly, existing TBM tunnel construction faces three major pain points: First, the timing of support is delayed. The existing anchored support system can only be operated after the TBM shield is exposed, which cannot timely restrain the initial large deformation of soft rock when crossing fault fracture zones. Second, the self-supporting capacity of the surrounding rock is not fully utilized. The area near the excavation face relies solely on the TBM shield and cutterhead for support, resulting in insufficient effective support and excessive displacement around the tunnel, as well as expansion of the plastic zone. Third, there is an imbalance between construction economy and convenience. Traditional pipe roof support and advanced small pipe grouting are difficult to construct and require large grouting volumes, which increases construction costs, seriously affects the project schedule, and easily leads to safety risks such as TBM shield jamming.

[0045] The core objective of this invention is to provide a rapid and proactive control method for large deformation in soft rock that is adapted to the characteristics of open-type TBM construction. Through the design of "timely support + graded reinforcement + synergistic bearing", it solves the problems of lagging support, waste of the self-supporting capacity of the surrounding rock, and high construction risks and costs in the existing technology.

[0046] The core technology system of this invention is a "dual-anchored synergistic support system," which consists of a short anchored support system (reference numeral 2) and a long anchored support system (reference numeral 1). The overall working logic is as follows: During TBM tunneling, before the shield (reference numeral 3) is exposed, the short anchored support system is promptly installed through the cutterhead side holes (reference numeral 4) to form an initial deformation control barrier in conjunction with the shield. After the shield is exposed, the long anchored support system is deployed in stages according to the degree of surrounding rock deformation for reinforcement, while forming a multi-synergistic bearing mechanism with the steel arch support, steel mesh, and emergency shotcrete. Finally, through the sequential design of "70m shotcrete system after the face + 1000m secondary lining," the full-cycle surrounding rock deformation control from the initial stage to the long stage is achieved.

[0047] The core innovation of this system lies in breaking the traditional model of "supporting after the shield is exposed" and advancing the timing of support intervention to the shield constraint stage. At the same time, through modular components, precise deployment, and graded reinforcement design, it achieves dual optimization of support effect and construction efficiency, providing technical support for the safe and efficient tunneling of open-face TBMs under soft rock and large deformation geological conditions.

[0048] The second aspect is layered and detailed: (a) Short anchorage support system: The short-anchored support system is key to achieving "active and timely support" in this invention, and its design revolves around the principles of "early intervention, rapid construction, and strong constraint." It includes: Firstly, structural reconstruction: core components and supplementary details. The short anchorage support system adopts a full-length anchorage structure. The anchorage material is high-strength threaded steel, and the model is determined according to the geological conditions of the tunnel site. Priority is given to HRB400E grade steel bars that meet the requirements of Article 5.3 of the "Q-CR9248-2020 Technical Specification for Anchorage Support in Railway Tunnels" to ensure that the tensile strength and yield strength of the anchorage meet the initial anchorage requirements.

[0049] The anchor bolt length is optimized according to the working conditions. Under normal geological conditions, a 3m or 4m specification is selected (corresponding to working conditions 1 and 2 in the embodiments). The anchor bolt diameter is 25mm. The bolt body is equipped with equally spaced annular shear bars with a spacing of 200mm and a height of 8mm to enhance the bonding force between the anchor bolt and the cement grout. The tail of the anchor bolt is equipped with a washer and a nut. The washer is made of a 10mm thick square steel plate (side length 150mm) with a 26mm diameter hole in the center to ensure a tight fit with the anchor bolt.

[0050] The drilling method is radial drilling perpendicular to the rock face, and the drilling area is strictly limited to the 180-degree area of ​​the upper half ring on the tunnel cross-section (as shown in the attached diagram). Figure 3As shown in the figure, this area covers the tunnel arch and both shoulders, which is the area where soft rock deformation is most concentrated and most prone to collapse; along the longitudinal direction of the tunnel, the short anchor support system is laid at intervals of 0.9m, forming a continuous circumferential constraint.

[0051] Through the side cutter hole of the TBM cutter head (attached) Figure 5 The installation is carried out according to the attached diagram (4). The diameter of the side cutter hole is 50mm, which is compatible with the diameter of the short anchor rod. No additional drilling channel is required, so the support operation and TBM tunneling can be synchronized.

[0052] Secondly, the connection relationship: The anchor bolt is bonded along its entire length. The diameter of the anchor bolt hole is 42mm, and the drilling depth is 100mm greater than the length of the anchor bolt. After drilling, the rock powder and water inside the hole are removed, and cement grout (water-cement ratio of 0.45:1) is injected. The grouting pressure is controlled at 0.3-0.5MPa to ensure that the cement grout fills the gap between the holes and achieves a tight bond between the anchor bolt and the surrounding rock along its entire length.

[0053] After the short anchor support system is installed, its tail pad is kept parallel to the inner wall of the TBM shield, with the spacing controlled within 50mm. Through the radial constraint of the shield on the surrounding rock, it forms a "rigid-flexible" constraint system with the anchor rod, avoiding excessive stress on the anchor rod alone, which could lead to failure.

[0054] Short anchor bolts within a 180-degree range of the same ring are connected by a Φ12mm steel ring beam. The steel ring beam is welded to the tail plate of the anchor bolt, with a welding length of not less than 100mm, forming a circumferential integral load-bearing structure, which improves the integrity and deformation resistance of the initial support.

[0055] Thirdly, the working principle: the three-in-one control logic of "timing-position-structure". The working principle of the short anchor support system can be clearly presented through the "action chain": TBM cutterhead excavation → before the shield is exposed (the surrounding rock is still constrained by the shield) → locate the drilling position through the cutterhead side holes → use a portable anchor drilling rig to drill holes radially and perpendicularly to the rock surface of the tunnel → clean the hole → inject cement grout → insert full-length anchor bolts → install pads and nuts for pre-tightening → reinforce with steel ring beam connection → work together with the TBM shield to form a deformation control system for the surrounding rock inside the shield shell.

[0056] The specific logic is as follows: Timing control: Choose to install the shield before it is exposed. At this time, the surrounding rock has not completely broken free from the shield's constraint and the deformation is in its initial stage. Timely intervention can effectively suppress the loosening and expansion of the surrounding rock and avoid the accumulation of deformation. Precise positioning: It is limited to the core deformation zone of the upper half ring of the tunnel cross section, which specifically solves the problems of easy collapse and large deformation of soft rock in the arch and shoulder, and avoids ineffective support; Structural adaptation: The full-length anchor bolt is bonded to the surrounding rock, which can fully mobilize the shear strength and tensile strength of the surrounding rock itself, transforming the surrounding rock from a "loose body" into a "load-bearing structure". At the same time, it works with the shield to share the load of the surrounding rock, reducing the proportion of the shield bearing the load alone.

[0057] Fourth, technical effectiveness: specifically addresses initial support issues. Addressing the pain point of "lagging support": Support is initiated earlier, during the shield constraint stage, 3-5 tunneling cycles earlier than traditional support methods. This effectively controls initial deformation of the surrounding rock. Example data shows that when using 4m long short anchor bolts (condition 2), the vertical displacement around the tunnel within the fault fracture zone (62m monitoring point) is only 9.55mm, and the horizontal displacement is 23.7mm, representing reductions of 16.9% and 15.7% respectively compared to support without short anchor bolts (condition 3). By using a full-length anchoring structure, the surrounding rock and the anchor bolt form a synergistic force-bearing body, reducing the range of the plastic zone near the TBM cutterhead. The working condition comparison shows that the plastic zone depth in working conditions 1 and 2 with short anchoring support is reduced by an average of more than 30% compared to working condition 3. By using the cutterhead side holes of the TBM as the installation channel, no additional working space is needed. The installation time for a single anchor bolt is only 15-20 minutes, which does not affect the normal tunneling rhythm of the TBM. The construction efficiency is more than 60% higher than that of traditional advanced support.

[0058] Fifth, visual aids in construction. Appendix Figure 3 (Cross-section diagram of short anchorage support system): Clearly shows the layout range of the short anchorage support system on the tunnel cross section (upper half ring 180 degrees), and marks the vertical relationship between the anchor bolts and the tunnel rock wall, the anchor bolt spacing and the connection method of the steel ring beam. Technicians can directly refer to this diagram to determine the drilling angle and circumferential layout density. Appendix Figure 5 (Schematic diagram of the installation location of the short anchor support system): The enlarged view shows the correspondence between the cutter hole on the side of the TBM cutterhead (label 4 in the attached diagram) and the short anchor bolt (label 2 in the attached diagram), which clarifies the channel position and positioning benchmark for the installation of the anchor bolt and avoids interference with the cutterhead structure during the installation process; Appendix Figure 4 (Longitudinal profile diagram of the anchorage support system): This diagram shows the spacing (0.9m) of the short anchorage support system along the longitudinal direction of the tunnel, as well as its positional relationship with the subsequent long anchorage support system, providing a visual basis for longitudinal construction layout.

[0059] (II) Long-anchored support system: The long-anchored support system is a key reinforcement component for achieving "full-cycle deformation control" in this invention. Its design revolves around the principles of "graded adaptation, precise reinforcement, and synergistic load-bearing." It includes: First, core components A graded structural design is adopted. When the surrounding rock deformation is small (deformation rate ≤ 30 mm / d), full-length anchor bolts are selected; when the surrounding rock deformation is large (deformation rate > 30 mm / d), prestressed anchor cables are selected. The parameters of the full-length anchor bolts are the same as those of the short anchor bolts (diameter 25 mm, length 8 m); the prestressed anchor cables use Φ21.8 mm steel strand, are 12 m long, have an anchoring section length of not less than 2 m, are anchored using resin anchoring agent, and have an anchoring force of not less than 300 kN.

[0060] The prestressed anchor cable is equipped with a steel pad (20mm thick, 200mm side length), anchorage and tensioning equipment. The anchorage is an OVM15-3 type, and the tensioning equipment is a YCW250 type jack. The tail of the full-length anchor rod is also equipped with a pad and nut to maintain structural consistency with the short anchorage system and facilitate standardized construction.

[0061] Based on the TBM construction technology, a spiral method is adopted for installation, with a spiral pitch of 0.9m (consistent with the longitudinal spacing of the short anchorages) and a spiral angle of 15-20 degrees, to ensure that the long anchorage system can form a uniform force network in both the cross-section and longitudinal section of the tunnel. Along the longitudinal direction of the tunnel, the long anchorage system and the short anchorage system are arranged alternately, that is, a row of long anchorage systems is set in the middle of two adjacent rows of short anchorage systems (corresponding to claim 7), with a longitudinal spacing of 0.9m.

[0062] Secondly, the corresponding connection relationships: Connection between the long anchoring system and the surrounding rock: The cement grout is used for full-length bonding, with a drilling diameter of 42mm and a grouting pressure of 0.3-0.5MPa. This process is consistent with the grouting process of the short anchoring system, which facilitates uniform construction. The anchoring section uses resin anchoring agent, and the stirring time is controlled at 30-40 seconds. After the anchoring agent solidifies (the strength reaches more than 80% of the design strength), tensioning is carried out. The tensioning sequence is symmetrical tensioning from the top of the arch to both sides. The tensioning control stress is 75% of the standard value of the tensile strength of the steel strand. After tensioning, locking is performed.

[0063] The tail pad of the long anchor bolt / anchor cable is connected to the steel ring beam of the adjacent short anchor system by a longitudinal steel bar with a diameter of Φ16mm. The longitudinal steel bars are spaced 0.9m apart, forming a longitudinal and transverse interwoven force network to achieve the coordinated load-bearing of the short and long anchors.

[0064] The long anchorage system works in conjunction with the steel arch support, steel mesh, and emergency shotcrete. The steel arch uses I20b I-beams with a spacing of 0.9m (consistent with the longitudinal spacing of the anchorage system). The steel arch is welded and fixed to the tail plate of the long anchorage. The steel mesh uses Φ8mm steel bars with a mesh spacing of 200×200mm, laid inside the steel arch, and tied and fixed to the steel arch and anchorage system. The emergency shotcrete uses C25 concrete with a spray thickness of 100mm, covering the steel mesh and steel arch, forming a composite support structure of "anchor bolts / anchor cables + steel arch + steel mesh + shotcrete".

[0065] Thirdly, the corresponding working principle: The working principle and action chain of the long anchorage support system: TBM shield exposure → monitoring the deformation rate of the surrounding rock → determining the deformation level → selecting full-length anchor bolts or prestressed anchor cables → positioning and drilling in a spiral pattern → drilling (depth greater than the outline of the loosened ring of the surrounding rock) → cleaning the hole → installing anchoring agent / grouting → inserting anchor bolts / anchor cables → fixing and tensioning (anchor cables) → connecting with the short anchorage system, steel arch frame, and steel mesh → jointly bearing the later load of the surrounding rock.

[0066] The specific logic is as follows: Graded adaptation: The support type is dynamically selected according to the degree of deformation of the surrounding rock. When the deformation is small, the full-length anchor bolts are used to deform together with the surrounding rock. When the deformation is large, the prestressed anchor cables are used to actively apply prestress to suppress the development of deformation and achieve "support on demand". Layout optimization: The spiral layout method can make the long anchorage system evenly distributed in the tunnel cross section, avoiding support blind spots. At the same time, the longitudinal interval matches the short anchorage system, forming a spatiotemporal synergy of "short anchorage controls the initial stage and long anchorage controls the later stage". Synergistic load bearing: It forms a composite support structure with steel arches, steel mesh, and shotcrete, which transfers the surrounding rock load to the deep stable surrounding rock through the anchoring system, and then disperses the load through the steel arches and shotcrete, thereby improving the overall support's resistance to deformation and its upper limit of load bearing.

[0067] Fourth, technical benefits: solves the problems of later deformation and insufficient load-bearing capacity. Precise measures were implemented for surrounding rock with different degrees of deformation. In areas with large deformation, prestressed anchor cables were used to actively control the shape, ensuring that the displacement around the tunnel remained within the design allowable range (≤30mm). In the example, at the 85m monitoring point (core area of ​​the fault fracture zone), the vertical displacement of condition 2 was 13.3mm and the horizontal displacement was 31.3mm, which were reduced by 27.3% and 15.4% respectively compared with condition 3. The spiral layout and longitudinal and transverse connections enable the long anchoring system, short anchoring system, and composite support structure to form a whole, avoiding local support failure. In the example, local anchor loosening occurred in working condition 3 without short anchoring support, while no support failure occurred in working conditions 1 and 2 with long and short anchoring coordination. Spiral installation can be carried out during the TBM excavation interval without occupying a separate construction window. It can be carried out in parallel with processes such as steel arch frame installation and shotcrete, and the construction efficiency is more than 40% higher than that of traditional graded support.

[0068] In summary, the collaborative support system consists of a "dual-anchoring + composite structure" full-cycle load-bearing component. It consists of a short anchorage support system, a long anchorage support system, steel arch support, steel mesh, emergency shotcrete, systematic shotcrete, and secondary lining, forming a full-cycle load-bearing logic of "initial constraint - later reinforcement - long-term stability".

[0069] First, the core components of the collaborative system Steel arch frame (I20b I-beams, 0.9m spacing) + steel mesh (Φ8mm, 200×200mm) + emergency shotcrete (C25, 100mm thickness) + system shotcrete (C25, 200mm thickness) + secondary lining (C30 cast-in-place concrete, 300mm thickness). Shotcrete support is carried out approximately 70m behind the working face, and secondary lining is carried out 1000m behind the working face. Shotcrete support is carried out 7 days after emergency shotcrete curing, and secondary lining is carried out after the shotcrete strength reaches 100% of the design strength.

[0070] Secondly, the method of coordinating and fixing each component. The steel arch frame is welded and fixed to the steel ring beam of the short anchorage system and the tail pad of the long anchorage system. Each steel arch frame is connected to no less than 4 anchor rods / cables to ensure that the steel arch frame does not shift or overturn. The steel mesh and steel arch frame are fixed by binding wire, with the binding points spaced no more than 300mm apart, to ensure that the steel mesh and steel arch frame are tightly fitted together and jointly bear the weight of the shotcrete and the pressure of the surrounding rock. Emergency shotcrete covers the steel arch frame and steel mesh, bonding tightly to the surrounding rock surface. System shotcrete covers the emergency shotcrete, forming a double-layer shotcrete structure. A waterproof membrane (EVA material, 1.5mm thick) is installed between the secondary lining and the system shotcrete. The waterproof membrane is fixed to the shotcrete surface by hot-melt welding.

[0071] Thirdly, the corresponding working principle: The working principle and action chain of the collaborative support system: short anchorage + shield to control initial deformation → steel arch frame + steel mesh + emergency shotcrete to seal the surrounding rock → graded reinforcement of long anchorage system → shotcrete reinforcement 70m behind the working face → long-term stability of secondary lining 1000m behind the working face.

[0072] The specific logic is as follows: The support function is allocated according to the time dimension of "initial-medium-long-term". In the initial stage (shield constraint stage), it is undertaken by short anchor + shield. In the medium stage (from shield exposure to 70m behind the face), it is undertaken by long anchor + composite support structure. In the long stage (after 1000m behind the face), it is undertaken by secondary lining, so as to achieve gapless support throughout the whole cycle. The anchoring system provides radial restraint, the steel arch provides circumferential support, the steel mesh enhances the tensile strength of the shotcrete, the shotcrete seals the surrounding rock to prevent weathering and water seepage, and the secondary lining provides the final load-bearing guarantee. The functions of each structure are complementary and they work together to bear the load. The initial focus is on "controlling deformation", the mid-term focus is on "strengthening load-bearing capacity" and the long-term focus is on "ensuring stability". Through functional classification, the dynamic support needs during construction are met, and the long-term safety of the tunnel during operation is guaranteed.

[0073] Fourth, technical benefits: solves the problems of overall support stability and long-term safety. The composite support structure and the double anchoring system work together to significantly improve the stiffness and strength of the support system. In the example, the maximum displacement around the hole in condition 2 (85m monitoring point) is only 31.3mm, which is far below the design allowable value (50mm). The secondary lining creates a long-term load-bearing system of "surrounding rock-support-lining" in the tunnel, avoiding support failure due to the accumulation of deformation in the later stage. Durability tests have verified that this collaborative system can meet the safety requirements of the tunnel for 50 years of operation. Emergency shotcrete promptly seals the surrounding rock to prevent weathering, rockfall, and water seepage. The long anchoring system and steel arch frame work together to suppress large deformations. In the example, no safety accidents such as TBM jamming or surrounding rock collapse occurred, and the construction risk was reduced by more than 80% compared with traditional methods.

[0074] Third aspect, verification of the embodiments: To further verify the effectiveness of the technical solution of the present invention, this embodiment sets up three working conditions for comparative testing. The working condition parameters, construction process and results are as follows: Firstly, working condition design Working Condition 1: Short anchorage support system length 3m + long anchorage support system (8m full-length anchorage bolts) + collaborative support structure (steel arch frame + steel mesh + shotcrete + secondary lining). Working Condition 2: Short anchorage support system length 4m + long anchorage support system (8m full-length anchorage bolts) + collaborative support structure; Condition 3 (control group): No short anchorage support system + long anchorage support system (8m full-length anchorage bolts) + collaborative support structure; Common parameters: Tunnel diameter 6m, traversing a fault fracture zone for 60m-110m, surrounding rock category V (fault fracture zone), lithological parameters taken from Table 2 (natural density 2000kg / m³). 3Elastic modulus 0.6-1.0 GPa, Poisson's ratio 0.37-0.39, internal friction angle 25-26°, cohesion 150-200 kPa; the physical and mechanical parameters of the anchoring system are taken from Table 1 (density 78.5 kN / m³). 3 Elastic modulus 200 GPa, cross-sectional area 2.91 cm² 2 The bonding strength is 50.33 kN / m, the stiffness is 9770 MN / m, and the grouting perimeter is 0.157 m.

[0075] Secondly, the construction process Construction process for working condition 1 When the TBM is excavated to mileage 25m (non-fault fracture zone), before the shield is exposed, 3m long short anchor bolts are installed through the cutterhead side holes, arranged in a 180-degree range with a longitudinal spacing of 0.9m. Construction is carried out in the order of "arch crown first, then arch shoulder" to complete the connection of the steel ring beam. Continue tunneling to mileage 60m (entering the fault fracture zone), maintain the construction pace of the short anchor support system, and simultaneously carry out emergency shotcrete construction (100mm thickness). After the shield is exposed (65m mileage), 8m long full-length anchor bolts are installed in a spiral pattern, with a 0.9m interval between them and the short anchor system, to complete the connection with the steel arch frame and steel mesh; When the tunnel reaches 130m (70m after the working face), systematic shotcrete construction (200mm thickness) will begin. When the tunnel reaches 1060m (1000m after the tunnel face), secondary lining construction (300mm thickness) will be carried out. Monitoring points were set up at mileages of 25m, 62m, 85m, 107m, and 150m to monitor the displacement around the tunnel in real time.

[0076] Construction process for working condition 2 The only difference from Condition 1 is that the length of the short anchorage support system is 4m, while the rest of the construction process and parameters are completely the same.

[0077] Construction process for working condition 3 The only difference from Condition 1 is that the short anchorage support system is not set up; the rest of the construction process and parameters are completely the same.

[0078] Third, experimental results and analysis Comparison of displacement data around the tunnel (Table 3 summary) ; IV. Results Analysis Within the fault fracture zone (monitoring points at 62m, 85m, and 107m): In working conditions 1 and 2 with short anchor support, the displacement around the tunnel was significantly lower than in working condition 3 without short anchor support. Among them, working condition 2 (4m short anchor support) had the best effect, with a vertical displacement reduction of 27.3% in the fault core area (85m), which fully verified the technical effect of the short anchor support system in "timely shape control". Non-fault areas (25m and 150m monitoring points): The differences in the displacement around the tunnel under the three working conditions are small, indicating that the short anchor support system mainly plays a role in soft rock areas with large deformation such as fault fracture zones, avoiding ineffective support and reflecting the design concept of "precision support". Synergistic effect of long and short anchorage: In working conditions 1 and 2, the long anchorage system and the short anchorage system worked together to keep the displacement around the tunnel stable within the design allowable range, without any sudden deformation, which verified the integrity and stability of the synergistic support system. The innovation of this invention lies in breaking the traditional "support after shield exposure" model and advancing the support timing to the shield constraint stage; achieving "support on demand" through graded support and precise layout; and fully leveraging the self-supporting capacity of the surrounding rock and the bearing capacity of the support structure through collaborative system design. Ultimately, it solves the core problems of existing technologies, such as delayed support, waste of the self-supporting capacity of the surrounding rock, and high construction risks and costs, providing a reliable technical solution for the construction of open-type TBMs under soft rock and large deformation geological conditions.

[0079] The above description is merely a preferred embodiment of this application and is not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. 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 controlling large deformation in soft rock suitable for the characteristics of TBM tunnel construction, characterized by: The control method is implemented based on an anchoring support system, which consists of a short anchoring support system and a long anchoring support system. The control method includes the following steps: During TBM excavation, before the shield is exposed, the aforementioned short anchor support system is promptly installed along the radial perimeter of the tunnel. After the TBM shield is exposed, it is reinforced by the long anchorage support system. Together, the two constitute the anchorage support system for rapid and active control of large deformations in the TBM tunnel. Furthermore, the control method and the anchoring support system are applicable to the construction scenarios of open-type TBMs.

2. The method for controlling large deformation in soft rock suitable for TBM tunnel construction as described in claim 1, characterized in that: The installation and support method of the short anchorage support system is as follows: The drilling is carried out radially perpendicular to the rock surface, and the drilling time corresponds to before the shield is exposed. The drilling range is limited to the 180-degree area of ​​the upper half ring on the tunnel cross-section.

3. The method for controlling large deformation in soft rock suitable for TBM tunnel construction as described in claim 2, characterized in that: The short anchorage support system adopts a full-length anchorage structure.

4. The method for controlling large deformation in soft rock suitable for TBM tunnel construction methods according to claim 2, characterized in that: The short anchorage support system, after timely support, forms a deformation control system for the surrounding rock inside the shield, including: By leveraging the effective constraint of the TBM shield on the surrounding rock and through the timely installation of a short-anchored support system, rapid construction and initial deformation control can be achieved.

5. The method for controlling large deformation in soft rock suitable for TBM tunnel construction methods according to claim 1, characterized in that: The support method for the long anchoring system after the TBM shield is exposed is as follows: When the surrounding rock deformation is small, the long anchoring system uses full-length anchor bolts to effectively control the shape by co-deforming with the surrounding rock. When the surrounding rock deformation is large, the long anchoring system uses prestressed anchor cables to actively control the surrounding rock deformation and ensure the support effect.

6. The method for controlling large deformation in soft rock suitable for TBM tunnel construction methods according to claim 5, characterized in that: The long anchorage system is based on TBM construction technology and is installed in a spiral manner.

7. The method for controlling large deformation in soft rock suitable for TBM tunnel construction methods according to claim 2, characterized in that: The long anchoring system and the short anchoring system are arranged in an alternating manner: Along the tunnel excavation direction, a long anchor support system is set in the middle of two adjacent rows of short anchor support systems, and the two work together to form a complete anchor support system.

8. The method for controlling large deformation in soft rock suitable for TBM tunnel construction methods according to claim 2, characterized in that: The short anchorage support system is installed radially along the tunnel through the side cutter holes of the TBM cutterhead.

9. The method for controlling large deformation in soft rock suitable for TBM tunnel construction as described in claim 1, characterized in that: The long anchorage support system, together with the steel arch support, steel mesh, and emergency shotcrete operation, will jointly bear the surrounding rock load.

10. The method for controlling large deformation in soft rock suitable for TBM tunnel construction methods according to claim 9, characterized in that: Shotcrete support is carried out approximately 70m behind the working face, and secondary lining construction is carried out 1000m behind the working face.

Images