A boulder treatment method for shield construction

Abstract

The present application relates to the technical field of tunnel construction, in particular to a boulder treatment method for shield construction, comprising the following steps: S1. Carrying out geological exploration to obtain boulder and environmental parameters; S2. Classification treatment: when the diameter of the boulder d is greater than or equal to 500 mm, the net distance of the pipeline is 250 mm≤D<1400 mm, and the seismic safety threshold V is less than 1.0 cm / s, the first type of treatment step is adopted: an anchoring hole is drilled from the ground to penetrate the boulder and extend to a predetermined depth below the boulder; a glass fiber reinforcement cage is lowered into the hole and concrete is poured to form an anchoring pile that penetrates the boulder; during shield tunneling, the boulder and the anchoring pile are cut and broken together by the cutter head. The present application defines the applicable boundary of the first type of method; the boulder is strongly bound to the stable stratum below by the anchoring pile, preventing the boulder from rotating under the torque of the cutter head, achieving efficient cutting without opening the cabin, and improving construction efficiency and safety.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for handling isolated boulders during shield tunneling. Background Technology

[0002] With the rapid development of urban rail transit, the shield tunneling method has been widely used in the excavation of underground tunnels. During tunnel excavation, uneven weathering of bedrock is frequently encountered, meaning that isolated boulders in spherical weathering (moderate to slightly weathered) form exist within residual soil or weathered rock. These boulders often have very high compressive strength and are classified as extremely hard rock, which can have a very adverse impact on shield tunneling construction.

[0003] During tunnel boring machine (TBM) excavation, when the cutterhead contacts a boulder, the enormous rotational torque breaks the binding force of the surrounding soft strata on the boulder, causing it to roll in front of the tunnel face or rotate in the same direction as the cutterhead. This not only prevents the boulder from being effectively broken by the cutterhead, but also causes it to jam the cutterhead, resulting in significant wear on the cutters and causing the TBM to deviate from its excavation axis. In severe cases, it can even prevent the TBM from advancing, delaying the construction schedule. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing shield tunneling methods, where boulders roll in front of the tunnel face or rotate in the same direction as the cutterhead, affecting shield tunneling and slowing down construction efficiency, and to provide a method for handling boulders in shield tunneling.

[0005] In a first aspect, the present invention provides a method for handling boulders during shield tunneling, comprising the following steps:

[0006] S1. Conduct supplementary geological exploration to obtain parameters of isolated boulders and environmental parameters of the construction site; S2. Based on the geological survey results, isolated boulders at the construction site will be classified and treated accordingly: When the diameter d of the boulder satisfies: d ≥ 500 mm, the net spacing D between pipelines at the construction site satisfies: 250 mm ≤ D < 1400 mm, and the permissible seismic safety velocity threshold V at the construction site is < 1.0 cm / s, the first type of boulder treatment steps are adopted, including: Drill a hole from the ground down, penetrate the boulder within the tunnel body, and continue drilling down to a predetermined depth below the boulder to form an anchoring hole that penetrates the boulder; Lower the fiberglass reinforcement cage into the anchoring hole; Concrete is poured into the anchoring hole to form an anchoring pile that penetrates the boulder, thereby anchoring and binding the boulder through the anchoring pile. During shield tunneling, the shield cutterhead is used to cut the boulders and anchor piles together.

[0007] This invention provides a method for handling isolated boulders during shield tunneling. By precisely defining environmental parameters and the geometric characteristics of the boulders, it clarifies the applicable boundaries of the first type of construction method. For constrained conditions such as the prohibition of conventional blasting, limited space preventing the entry of large equipment, and large boulders unsuitable for integral grouting or dense slot drilling, the invention proposes the use of anchor piles. By penetrating the boulder with anchor piles, the boulder is effectively anchored to the stable strata or bedrock below, forming a strong anchoring constraint. This allows the boulder to remain stationary when facing cutterhead torque, enabling effective rock breaking by the cutterhead. Through this pretreatment with anchor piles, during shield tunneling, the cutterhead can cut through the boulder and anchor pile together without stopping the machine for hatch opening or secondary muck removal, improving construction efficiency and avoiding delays in the construction schedule.

[0008] Fiberglass reinforced cages were used instead of traditional steel cages, which ensured high-strength and stable restraint of boulders during the pretreatment stage. Due to their excellent machinability, they can be directly cut by the cutterhead during tunnel boring machine (TBM) excavation, avoiding the risk of traditional high-strength steel bars getting stuck on the TBM cutterhead or breaking the cutters, thus extending the life of the cutters.

[0009] Preferably, in the first type of boulder treatment step, continuing to drill downwards to a predetermined depth below the boulder includes: continuing to drill downwards to at least 2m below the bedrock surface below the boulder, and the bottom elevation of the anchor hole is located at no less than 1m below the bottom elevation of the tunnel.

[0010] By drilling anchor holes at least 2m into the bedrock surface, sufficient embedment depth of the anchor piles in the underlying stable rock mass is ensured, preventing the anchor piles from overturning or loosening. The bottom elevation of the hole is at least 1m lower than the bottom elevation of the tunnel, ensuring that the anchor piles can completely penetrate the entire cross-section of the tunnel excavation and penetrate deep into the tunnel foundation, avoiding local rollover or instability of the bottom of the boulder due to incomplete anchoring, and improving the anchoring stability of the boulder.

[0011] Preferably, in the first type of isolated rock treatment step, the diameter of the pilot hole is 250mm, and the top of the anchor pile is 500mm below the ground elevation.

[0012] Preferably, in the first type of boulder treatment step, when the boulder diameter d satisfies 1m≤d<2m, the number of anchor holes is 1; When the diameter d of the boulder satisfies 2m≤d<3m, the number of anchor holes is 2; When the diameter d of the boulder satisfies 3m≤d<4m, the number of anchor holes is 4; When the diameter d of the boulder satisfies 4m≤d<5m, the number of anchor holes is 6; When the diameter d of the boulder satisfies 5m≤d≤6m, the number of anchor holes is 8.

[0013] By classifying the size of boulders, the anchoring restraint force and the volume of the boulders were matched; while ensuring that large-diameter boulders have multi-point spatial constraints, the construction redundancy and cost waste caused by excessive drilling of small-diameter boulders were avoided.

[0014] Preferably, in S2, when the permissible seismic safety velocity threshold V at the construction site is ≥1.0 cm / s, the second type of boulder treatment step is adopted, including: Within the area of ​​the isolated rock, blasting holes are drilled, and multiple rows of blasting holes are arranged in a dot matrix pattern with a hole spacing and row spacing of no more than 0.75m. During detonation, the blast holes located at the edge of the boulder are detonated first, and then the blast holes located in the middle of the boulder are detonated one by one. After the blasting is completed, holes are drilled and grout is injected into the blasting area to consolidate the blasted fragments; During shield tunneling, the shield cutterhead is used to cut the grout-consolidated explosive fragments.

[0015] When site conditions permit blasting, this highly efficient rock-breaking method is prioritized. The lattice-patterned layout of the blasting holes ensures a uniform, high-density release of explosive energy within the boulder, guaranteeing its full expansion and disintegration into smaller fragments. During detonation, the blasting holes at the boulder's edge are detonated first, using edge blasting to compress the surrounding soil and create a free surface. Subsequently, the central blasting holes are detonated one by one, reducing resistance and clamping forces within the boulder and improving explosive energy utilization and hard rock fracturing. After blasting, grout is injected into the blasted area to fill cracks and cavities between fragments, re-cementing and solidifying the discrete blasted fragments into a unified whole. This transforms the originally high-strength boulder into an easily machinable cemented fragment composite, allowing the tunnel boring machine (TBM) cutterhead to continuously cut through it without needing to stop for cleaning, thus improving construction efficiency and ensuring cutter safety.

[0016] Preferably, in the second type of boulder treatment step, of the two adjacent blasting holes, one blasting hole is drilled to the bottom surface of the boulder and explosives are loaded from the bottom of the hole upwards to a distance of 10cm from the top surface of the boulder; the bottom of the other blasting hole is 10cm from the bottom surface of the boulder and explosives are loaded from the bottom of the hole upwards to a distance of 10cm from the top surface of the boulder.

[0017] By setting adjacent blasting holes in a staggered charging structure, it is beneficial to eliminate the blasting dead zone at the bottom of the boulder, ensuring that the boulder can be fully impacted and broken up.

[0018] Preferably, in S2, when the net spacing D between pipelines at the construction site is ≥1400mm and the permissible seismic safety velocity threshold V at the construction site is <1.0cm / s, the third type of boulder treatment step is adopted, including: Install steel casing; Use a rotary drilling rig to perform rotary drilling operations, drill through the boulder and drill downwards to at least 1m below the bottom elevation of the shield tunnel; After drilling, a hole cleaning operation is carried out to remove isolated rocks and debris. Then, mortar is used to backfill the rotary drilling hole to the ground to form a pile. During shield tunneling, the shield cutterhead is used to cut rotary piles.

[0019] When site conditions do not permit conventional blasting but allow for the use of large rotary drilling rigs, the rotary drilling method is preferred for handling isolated boulders. This method fully utilizes spatial advantages, directly physically removing the boulders. After drilling, mortar is used to backfill the borehole, forming rotary piles and replacing the original high-compressive-strength, hard boulders with mortar piles. During tunnel boring, the cutterhead only needs to cut the homogeneous rotary piles, improving construction efficiency.

[0020] Preferably, in S2, when the net spacing D of pipelines at the construction site satisfies: 150mm ≤ D < 250mm, and the permissible seismic safety velocity threshold V at the construction site is < 1.0cm / s, the fourth type of boulder treatment step is adopted, including: Multiple rows of holes are drilled using a drilling rig, with the extension direction of each row of holes parallel to the centerline of the shield tunnel. The holes are drilled to a depth of at least 1 meter below the bottom elevation of the shield tunnel. The spacing between the rows of holes is no more than 400 mm, and the boulder is cut and separated into multiple sheet-like stones with a thickness of no more than 300 mm. After drilling is completed, grouting and sealing operations are carried out on the boreholes. During shield tunneling, the shield cutterhead is used to cut through the drainage holes and the sheet-like rocks together.

[0021] When the clearance between pipelines at the construction site is narrow, large rotary drilling equipment cannot enter the site, and conventional blasting is strictly prohibited, the drilling-through-row method is preferred for treating boulders. Multiple rows of holes are used to divide the boulders into sheet-like blocks no more than 300mm thick, making them easily crushed or overturned and cut off by the thrust and cutting force of the tunnel boring machine (TBM). After drilling, grouting is performed to seal the holes, filling the cavities left by the rows and providing appropriate filling and constraint for the sheet-like blocks. During TBM tunneling, the TBM cutterhead can cut through the grout-sealed rows of holes along with the sheet-like blocks, improving construction efficiency.

[0022] Preferably, in step S2, when the diameter d of the boulder satisfies d < 500 mm, the fifth type of boulder treatment step is adopted, including: Multiple rows of grouting holes are drilled on the ground using a drilling rig. The plane range of the grouting holes covers an area of ​​at least 2.5m radially outward from the boulder and at least 5m along the tunnel boring direction. The depth of the grouting holes extends at least 2.5m below the bottom of the boulder. After drilling is completed, grout is injected from the bottom of the hole upwards to consolidate and reinforce the strata in the boulder area, forming a grouting consolidation zone; During shield tunneling, the shield cutterhead is used to cut the grouting consolidation area and the isolated boulders inside.

[0023] For small-diameter boulders, the costly and complex method of in-situ rock breaking was abandoned in favor of an integral grouting reinforcement method. Grouting reinforces the surrounding strata, forming a grouting consolidation zone that encapsulates the small boulder. This grouting consolidation zone extends at least 5 meters forward along the tunnel boring machine (TBM) advance, providing positive thrust to the boulder and preventing it from escaping or rolling forward during cutterhead operation. During TBM tunneling, the cutterhead can directly cut through the grouting consolidation zone and the small boulders within it, significantly improving construction efficiency.

[0024] Preferably, in S2, when the net spacing D of pipelines at the construction site satisfies: 110mm ≤ D < 150mm, and the permissible seismic safety velocity threshold V at the construction site is < 1.0cm / s, the sixth type of boulder treatment step is adopted, including: Multiple splitting holes were drilled inside the boulder using a ring-combined layered method, with the spacing between adjacent layers controlled at 400 mm and the circumferential spacing between the splitting holes in each layer at 500~800 mm. After the splitting hole is drilled, the splitting rod is lowered into the splitting hole and pressure is applied to expand the boulder until the width of the crack in the boulder expands to at least 5cm. After the expansion and cracking are completed, grout is injected into the splitting hole to consolidate the split fragments; During shield tunneling, the shield cutterhead is used to cut the grout-consolidated fragments.

[0025] When the net spacing between pipelines at the construction site is extremely close, and conventional blasting is strictly prohibited, deep-hole fracturing is the preferred method for treating boulders. The expansion force generated by a hydraulic fracturing rod destroys and disintegrates the overall structure of the boulder. After fracturing, grout is injected into the fracturing holes and internal cracks of the boulder to fill the cavities created by the fracturing and cement the fracturing fragments, thus re-locking the discrete fragments into a softer, more easily cuttable whole. During tunnel boring machine (TBM) excavation, the cutterhead can directly cut through the grout-bonded fracturing fragments, improving construction efficiency.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for handling isolated boulders during shield tunneling. By precisely defining environmental parameters and the geometric characteristics of the boulders, the applicable boundaries of the first type of construction method are clarified. For constrained conditions such as the prohibition of conventional blasting, limited space preventing the entry of large equipment, and large boulders unsuitable for integral grouting or dense slot drilling, the method of constructing anchor piles is proposed. By penetrating the boulders with anchor piles, the anchor piles act as if nailing the boulders to the stable strata or bedrock below, forming a strong anchoring constraint. This allows the boulders to remain stationary when facing the torque of the cutterhead, thus enabling the cutterhead to effectively break the rock. With the pretreatment of the anchor piles mentioned above, the shield cutterhead can cut through the boulders and anchor piles together during shield tunneling without stopping the machine to open the hatch or performing secondary slag removal, thus improving construction efficiency and avoiding delays in the construction period. The use of fiberglass reinforced cages instead of traditional steel cages ensures high-strength and stable restraint of the boulders during the pretreatment stage. Due to their excellent machinability, they can be directly cut by the cutterhead during shield tunneling, avoiding the risk of traditional high-strength steel bars getting stuck on the shield machine cutterhead or breaking the cutters, and extending the life of the cutters. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of anchoring a boulder with an anchor pile.

[0028] Figure 2 A schematic diagram of the reinforcement configuration for a glass fiber reinforced cage.

[0029] Figure 3 This is a schematic diagram of the hole layout for blasting a boulder.

[0030] Figure 4 This is a schematic diagram of the explosive loading structure for blast holes when the thickness of the boulder is less than 2m.

[0031] Figure 5 A schematic diagram of the explosive charge structure for a blast hole when the thickness of the boulder is 2m to 3m.

[0032] Figure 6 This is a schematic diagram of the explosive loading structure for blast holes when two boulders overlap.

[0033] Figure 7 This is a diagram illustrating the effect of an explosion.

[0034] Figure 8 This is a schematic diagram of the plan view of the ground-level perforation.

[0035] Figure 9 A schematic diagram of the grouting reinforcement around the isolated rock.

[0036] Figure 10 A schematic diagram of the cross-section of the grouting reinforcement around the isolated rock.

[0037] Figure 11 This is a schematic diagram of the arrangement of the annular and layered holes for splitting.

[0038] Figure 12 This is a schematic diagram of a lone rock splitting apart.

[0039] Marked in the image: 1-Isolated rock, 2-Fiberglass reinforced cage, 3-Anchor pile, 4-Blast hole, 5-Drill hole, 6-Grouting hole, 7-Grouting consolidation zone, 8-Split hole, 9-Split rod. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0041] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0042] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0043] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0044] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0045] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0046] Example 1 This embodiment provides a method for handling isolated boulders during shield tunneling construction, including the following steps: S1. Conduct supplementary geological exploration to obtain parameters of boulder 1 and environmental parameters of the construction site.

[0047] In this embodiment, prior to construction, a detailed geological supplementary survey and on-site environmental investigation were conducted based on the project's geological data, specifically including: Geological drilling and edge finding: Geological exploration holes are drilled along the centerline of the shield tunnel at preset intervals (e.g., every 2m) to explore down to at least 1m below the bottom elevation of the tunnel. If the exploration reveals that there is a boulder 1 within the tunnel body, the concentric circle multi-ring drilling method with equal spacing from the inside to the outside is used as the center to find the edge ring by ring, accurately exploring the three-dimensional geometric shape, physical boundary and spatial location of the boulder 1. If necessary, cross-hole seismic wave CT geophysical exploration method is combined to set up transmitting and receiving holes in the core area, and use electric spark source and three-component geophone to collect seismic wave signals. Wave velocity imaging map is obtained through inversion calculation to further refine the verification of the size and burial depth of the boulder 1.

[0048] Pipeline inspection and exploration: Before excavation and drilling, the pipeline ownership unit shall be contacted, and the distribution, direction, type and net spacing D of underground pipelines shall be comprehensively investigated by using instrument detection combined with manual excavation of trenches / holes (the trench excavation depth shall not be less than 1.5m and the hole depth shall not be less than 3m).

[0049] Comprehensive parameter acquisition: Through the above geological supplementation and pipeline investigation, the parameters of boulder 1 (including boulder diameter d, three-dimensional dimensions, burial depth and hardness / compressive strength) and the environmental parameters of the construction site (including the net spacing of pipelines at the construction site D, the distance R of surrounding sensitive buildings / pipelines from the blasting center, and the permissible seismic safety velocity threshold V at the construction site) were accurately obtained.

[0050] In this embodiment, the seismic safety velocity threshold V refers to the maximum permissible peak mass vibration velocity (unit: cm / s) to ensure the structural safety and normal use of existing buildings, underground pipelines (such as gas and water supply pipelines), and existing rail transit facilities around the construction site. It is obtained as follows: First, the basic safety standard is determined by referring to tables in the "Safety Regulations for Blasting" (GB 6722), combined with local administrative control requirements; before project implementation, blasting vibration meters and triaxial vibration velocity sensors are deployed on the protected objects (such as building foundations and the ground surface corresponding to pipelines) to monitor the mass vibration velocity generated by the test blast in real time, and based on the Sadovsky formula:

[0051] The formula is obtained through data regression calculation and calibration, where Q is the maximum single-stage charge (unit: kg), R is the distance from the blasting center to the protected object (unit: m), K is a coefficient related to geological conditions, and α is the blasting attenuation index.

[0052] S2. Based on the geological survey results, the isolated boulder 1 at the construction site was classified and treated accordingly: When the supplementary survey reveals that the diameter d of boulder 1 satisfies: d ≥ 500 mm, and the net spacing D of pipelines at the construction site satisfies: 250 mm ≤ D < 1400 mm, and the permissible seismic safety velocity threshold V at the construction site is < 1.0 cm / s, if Figure 1 , Figure 2 As shown, the first type of isolated rock treatment steps include: Using a drilling rig (such as a geological drilling rig), a vertical pilot hole is drilled from the ground down, penetrating the boulder 1 located within the tunnel body, and continuing to drill down to a predetermined depth below the boulder 1 (to the bedrock below the boulder 1 or a predetermined depth), forming an anchoring hole that runs through the boulder 1 from top to bottom.

[0053] Specifically, in this embodiment, the process of continuing to drill downwards to a predetermined depth below boulder 1 is implemented according to the following dual depth control criteria: Rock embedment depth control: After drilling through boulder 1, the drilling rig passes through the weak soil layer or residual soil layer below boulder 1 and continues to drill down to at least 2m below the bedrock surface (such as moderately weathered or slightly weathered bedrock surface) below boulder 1 (i.e., the depth of the pile bottom into the rock is ≥2m).

[0054] Tunnel elevation control: While ensuring that the above-mentioned rock embedment depth is met, the final elevation of the bottom of the anchor hole is controlled to be no less than 1m below the bottom elevation of the shield tunnel (tunnel floor / lower outline of the tunnel body).

[0055] By drilling the anchoring hole at least 2m into the bedrock surface, sufficient embedment depth of the anchoring pile 3 in the lower stable rock mass is ensured, preventing the anchoring pile 3 from overturning or loosening. The bottom elevation of the hole is at least 1m lower than the bottom elevation of the tunnel, ensuring that the anchoring pile 3 can completely penetrate the entire cross-section of the tunnel excavation and penetrate deep into the tunnel foundation, avoiding local rollover or instability of the bottom of the boulder 1 due to incomplete anchoring, and improving the anchoring stability of the boulder 1.

[0056] After the anchor hole is formed and cleaned and passes inspection, the fiberglass reinforcement cage 2 is lowered into the anchor hole.

[0057] Concrete is poured into the anchoring hole to form an anchoring pile 3 that penetrates the boulder 1, thereby anchoring and binding the boulder 1 through the anchoring pile 3.

[0058] During shield tunneling, the shield cutterhead is used to cut through the boulder 1 and the anchor pile 3 together.

[0059] Furthermore, in this embodiment, the diameter of the pilot hole is 250mm, and the top elevation of anchor pile 3 is controlled to be 500mm lower than the ground elevation (i.e., the pile top burial depth is not less than 0.5m).

[0060] In this embodiment, the glass fiber reinforced cage 2 is a reinforced cage made entirely of glass fiber reinforced polymer (GFRP). The main reinforcement, stirrups, and stiffening hoops of the cage are all made of high tensile strength, low shear strength glass fiber reinforced polymer (GFRP / Plastic). Figure 2 As shown, the overall outer diameter of the fiberglass reinforced cage 2 is set to Φ200mm, matching the 250mm diameter of the pilot hole, ensuring smooth lowering of the cage and a uniform concrete protective layer around its perimeter. The longitudinal main reinforcement uses Φ14mm diameter fiberglass bars, evenly distributed circumferentially along the cage's circumference. The spiral stirrups use 10mm diameter fiberglass bars, continuously wound and bound along the cage's axial direction at 200mm intervals. To prevent bending deformation during hoisting and lowering, a 12mm diameter fiberglass stiffening hoop is installed every 2000mm longitudinally inside the cage. Positioning pads are provided around the cage to ensure that the net protective layer thickness on both the inner and outer sides of the anchor pile 3 is not less than 25mm.

[0061] Furthermore, in this embodiment, after the anchor hole is cleaned and inspected to ensure it is qualified, C30 underwater concrete is poured using the tremie method to form the pile. A second cleaning of the hole is performed before concrete pouring to control the thickness of sediment at the bottom of the hole to no more than 50mm, ensuring close contact between the pile bottom and the underlying bedrock and preventing weak interlayers at the pile bottom that could lead to anchor failure. During concrete pouring, the filling coefficient is controlled between 1.1 and 1.3 to ensure the pile body is dense and free of shrinkage cavities; the verticality deviation of the hole is controlled to no more than 2‰ (or 1 / 200), and the deviation of the pile position plane and pile diameter are both controlled within ≤50mm to ensure that the anchor pile 3 penetrates and locks into the boulder 1.

[0062] Furthermore, in this embodiment, the number of anchor holes (and subsequently formed anchor piles 3) is not fixed, but is matched in a stepped manner according to the diameter d (or equivalent projected geometric dimension) of the boulder 1 obtained from the geological supplementary exploration. The specific number of anchor holes is set as follows: When the diameter d of boulder 1 satisfies 1m≤d<2m, the number of anchor holes is 1; When the diameter d of boulder 1 satisfies 2m≤d<3m, the number of anchor holes is 2; When the diameter d of boulder 1 satisfies 3m≤d<4m, the number of anchor holes is 4; When the diameter d of boulder 1 satisfies 4m≤d<5m, the number of anchor holes is 6; When the diameter d of boulder 1 satisfies 5m≤d≤6m, the number of anchor holes is 8.

[0063] In some extremely complex weathered strata, if geological exploration reveals that the diameter d of boulder 1 is greater than 6m, the number of anchor holes should be increased proportionally from the original 8 (for example, based on the planar projected area of ​​boulder 1, according to an increase of 1~1.5m). 2 By adding one anchor hole to the projected area, 10, 12 or more anchor holes can be arranged. By classifying the size of boulder 1, the anchoring restraint force is matched with the volume of boulder 1; while ensuring that large-diameter boulder 1 has multi-point spatial constraints, the construction redundancy and cost waste caused by excessive drilling of small-diameter boulder 1 are avoided.

[0064] The shield tunneling method for handling isolated boulders provided in this embodiment clarifies the applicable boundaries of the first type of construction method by precisely defining environmental parameters and the geometric characteristics of the isolated boulder 1. For restricted working conditions where conventional blasting is strictly prohibited, the limited space for pipelines prevents large equipment from entering the site, and the large diameter of the isolated boulder 1 makes integral grouting or dense slot drilling unsuitable, the method of constructing anchor piles 3 is proposed. By penetrating the isolated boulder 1 with anchor piles 3, the anchor piles 3 act as if nailing the isolated boulder 1 to the stable strata or bedrock below, forming a strong anchoring constraint. This allows the isolated boulder 1 to remain stationary when facing the torque of the cutterhead, thus enabling effective rock breaking by the roller cutter. Through the pretreatment with anchor piles 3, during shield tunneling, the shield cutterhead can cut through the isolated boulder 1 and anchor piles 3 together without stopping the machine for hatch opening or secondary slag removal, improving construction efficiency and avoiding delays in the construction period.

[0065] Fiberglass reinforced cage 2 was selected to replace the traditional steel cage. In the pretreatment stage, it ensured the high strength and stability of the boulder 1. Due to its excellent machinability, it can be directly cut by the cutterhead during shield tunneling, avoiding the risk of traditional high-strength steel bars getting stuck on the shield machine cutterhead or breaking the cutter, thus extending the cutter life.

[0066] Example 2 Based on Example 1, the method for handling isolated boulders in shield tunneling construction provided in this example further classifies and treats isolated boulders 1 at the construction site according to the geological survey results: When the permissible seismic safety velocity threshold V at the construction site is ≥1.0 cm / s, the second type of boulder treatment procedure (deep-hole blasting method) is adopted, including: Drill blasting holes 4 within the area of ​​boulder 1, such as Figure 3 As shown, the hole spacing is no greater than 0.75m. Figure 3 Mid-distance a) and row spacing ( Figure 3 (b) At medium distance, multiple rows of blasting holes are arranged in a dot matrix pattern.

[0067] When drilling blast hole 4, a geological drilling rig or down-the-hole drilling rig can be used to drill vertically downwards from the ground. The hole diameter is set to 110mm. After drilling, a 90mm diameter PVC protective sleeve with a bottom plug is immediately buried in the hole to prevent the hole wall from collapsing and blocking the hole.

[0068] During detonation, the blasting holes 4 located at the edge of boulder 1 are detonated first, and then the blasting holes 4 located in the middle of boulder 1 are detonated one by one.

[0069] After the blasting is completed, the boreholes are sampled and cored using a geological drilling rig. The standard for qualified blasted rock fragments is that the unidirectional length of the extracted complete rock core is ≤30cm, ensuring that boulder 1 has been broken into fragments that are easy for the shield cutterhead and the soil removal system to suck up and remove.

[0070] After the blasting is completed, a retractable drilling and injection machine is used to drill holes in the blasting area and inject grout (such as cement-water glass dual-liquid grout). The grout fills and interweaves to consolidate the gaps between the rocks and the surrounding soil created by the blasting.

[0071] During shield tunneling, the shield cutterhead is used to cut the grout-consolidated explosive fragments.

[0072] When site conditions permit blasting, this highly efficient rock-breaking method is prioritized. The 4-hole array of blasting holes ensures a uniform, high-density release of explosive energy within boulder 1, guaranteeing its full expansion and disintegration into smaller fragments. During detonation, the blasting holes 4 located at the edge of boulder 1 are detonated first, using edge blasting to compress the surrounding soil and create a free surface. Subsequently, the blasting holes 4 in the center are detonated one by one, reducing resistance and clamping forces within boulder 1, improving explosive energy utilization and hard rock fracturing. After blasting, grout is injected into the blasted area to fill cracks and cavities between fragments, re-bonding and solidifying the discrete blasted fragments into a single unit. This transforms the originally high-strength boulder 1 into an easily cuttable, bonded fragment composite, allowing the tunnel boring machine cutterhead to continuously cut through it without stopping for cleaning, improving construction efficiency and ensuring cutter safety.

[0073] Furthermore, such as Figure 4 As shown, for a single boulder 1 with a thickness within a certain range (e.g., less than 2.0m), in two adjacent blasting holes 4, one blasting hole 4 is drilled downwards and completely penetrates the boulder 1 to reach its bottom surface. During charging, the explosive charge is continuously loaded upwards from the bottom of this blasting hole 4 (i.e., at the elevation of the bottom surface of the boulder 1), ending 10cm from the top surface of the boulder 1. That is, this blasting hole leaves a buffer section of 10cm in height (h1=10cm) without explosives on the top surface of the boulder 1. The other adjacent blasting hole 4 is drilled into the interior of the boulder 1, with its bottom 10cm from the bottom surface of the boulder 1. During charging, the explosive charge is continuously loaded upwards from the bottom of this hole (i.e., 10cm from the bottom surface of the boulder 1), also ending 10cm from the top surface of the boulder 1. That is, the blast hole has a buffer section with a height of h1=10cm on the top surface of boulder 1 without explosives and a rock mass protection section with a height of h2=10cm on the bottom surface of boulder 1 without explosives.

[0074] By setting the adjacent blasting holes 4 into a staggered charging structure, it is beneficial to eliminate the blasting dead zone at the bottom of boulder 1 and ensure that boulder 1 can be fully impacted and fully fractured.

[0075] like Figure 5As shown, in the second type of boulder treatment step (deep-hole blasting method), when the thickness of a single boulder 1 revealed by geological supplementary exploration is relatively large (for example, the thickness of boulder 1 is in the range of 2.0m~3.0m), each blasting hole 4 adopts an in-hole segmented (interval) charging structure: after the blasting hole 4 drills vertically through the boulder 1 from the ground, the charging is divided into an upper charging package and a lower charging package along the axial length of the borehole inside the boulder 1; between the upper charging package and the lower charging package, there is an intermediate filling interval section without charging (e.g., Figure 5 The diagonal-patterned filling area in the middle of the interior of the isolated rock 1 is shown.

[0076] like Figure 6 As shown, when geological exploration reveals multiple isolated boulders 1 with overlapping or intersecting vertical spaces (e.g., an upper boulder separated by a soil layer or soft rock layer and a lower boulder), each blasting hole 4 adopts a cross-layer continuous drilling and layered charging structure: the blasting hole 4 is drilled vertically downwards from the ground, with one hole continuously penetrating the upper boulder 1, the intermediate soil / soft rock interlayer, and the lower boulder 1. During charging, the explosive charge is precisely filled only in the axial sections of the blasting hole 4 that pass through the upper boulder 1 and the axial sections that pass through the lower boulder 1 (e.g., ...). Figure 6 The black-filled areas inside the two isolated rocks are shown.

[0077] like Figure 7 As shown ( Figure 7 (The two blasting holes 4 on the left are blasted holes; the one blasting hole 4 on the right is an unblasted hole). After the explosive blasting, the original intact and hard boulder 1 was fragmented, forming a blasted rock mass composed of a large number of small rock fragments.

[0078] Furthermore, when the net spacing between pipelines at the construction site D ≥ 1400 mm, and the permissible seismic safety velocity threshold V < 1.0 cm / s at the construction site, the third type of isolated rock treatment procedure (rotary drilling and rock removal method) is adopted, including: The construction site was leveled and hardened, and a total station was used to determine the axis and planar position of the rotary drilling hole.

[0079] Excavate and install steel casing at the proposed drilling location. The steel casing is made of steel plate with a thickness of 4-8mm, and the inner diameter of the casing is set at 1400mm. The top of the casing is 20-30cm above the original ground level. During installation, clay is symmetrically layered and compacted around the casing to ensure that the verticality deviation of the casing is ≤3 / 1000, preventing mud loss and surface collapse.

[0080] Rotary drilling rigs (full-rotation casing drilling rigs) are used for rotary drilling operations. After the rotary drilling rig is in place, the verticality of the drill rod is adjusted. A 1200mm diameter roller cone drill bit (such as a Bauer roller cone drill bit) is selected as the drill bit. The high-pressure crushing action of the roller cone mechanically crushes and grinds the boulder.

[0081] During drilling, sodium-based bentonite was used to prepare circulating drilling mud for borehole wall protection. The mud specific gravity was controlled between 1.05 and 1.15 g / cm³. 3 The viscosity is no greater than 28s and the sand content is less than 8%. The pressure of the mud column is used to maintain the stability of the borehole wall and prevent borehole collapse during drilling.

[0082] When the size of boulder 1 is large or it is distributed in a group of boulders, multiple rotary drilling holes with a spacing of 1200mm can be arranged in a quincunx pattern. The rotary drilling rig directly drills through boulder 1 and continues to drill downwards to at least 1m below the bottom elevation of the shield tunnel (the lower outline of the tunnel floor slab), ensuring that the boulder 1 that has intruded into the tunnel body section and the disturbed area of ​​the floor slab is removed.

[0083] After drilling to the designed depth, slightly raise the drill bit 10-20cm from the bottom of the hole and let it idle to stir. Then, use a positive or reverse circulation cleaning process to crush and remove the stone chips and rock fragments suspended in the mud and settled at the bottom of the hole, and control the thickness of the sediment at the bottom of the hole to ≤100mm.

[0084] After the hole is cleaned and inspected and the steel casing is removed, low-strength, easily machinable M5 cement mortar (or low-strength concrete) is continuously poured into the rotary drilling hole for backfilling until the rotary drilling hole is completely backfilled from the bottom of the hole to the ground surface. After solidification, an easily machinable rotary drilling mortar pile is formed.

[0085] During shield tunneling, the shield cutterhead is used to cut rotary piles.

[0086] When site conditions do not permit conventional blasting but allow for the use of large rotary drilling equipment, the rotary drilling shovel method is preferred for treating boulder 1. This method fully utilizes the available space by physically removing boulder 1 directly. After drilling, mortar is used to backfill the borehole, forming a rotary pile and replacing the original high-compressive-strength, hard boulder 1 with a mortar pile. During tunnel boring, the cutterhead only needs to cut the homogeneous rotary pile, improving construction efficiency.

[0087] Furthermore, when the net spacing D of pipelines at the construction site satisfies: 150mm ≤ D < 250mm, and the permissible seismic safety velocity threshold V at the construction site is < 1.0cm / s, the fourth type of boulder treatment procedure (drilling method) is adopted, such as... Figure 8 As shown, it includes: Due to the narrow net spacing of the pipelines (150mm≤D<250mm), large machinery cannot be placed. In this step, a light drilling rig (such as a geological drilling rig or a small down-the-hole drilling rig) with small footprint and high flexibility is selected to drill multiple rows of holes vertically from the ground.

[0088] like Figure 8As shown, the extension direction of each row of holes 5 on the plane is parallel to the centerline direction of the shield tunnel (i.e., the direction of the shield excavation axis). The borehole diameter of the row of holes 5 is selected to be 110~200mm (preferably 150~200mm); the spacing between multiple rows of holes 5 in the direction perpendicular to the tunnel centerline is set to no more than 400mm. Within the same row of holes 5, adjacent holes are drilled continuously close together (even partially overlapping and tangential), covering the projection area of ​​the boulder 1 within the tunnel cross-section.

[0089] Each row of holes 5 drills downwards through the boulder 1 and continues drilling downwards to at least 1m below the bottom elevation of the shield tunnel (the lower outline of the tunnel floor), ensuring that all boulders 1 intruding into the entire tunnel cross-section and the disturbed area of ​​the floor are cut through by the vertical rows of holes 5. The densely arranged rows of holes 5 form multiple cutting surfaces inside the boulder 1, mechanically cutting and separating the originally intact, highly compressive-resistant boulder 1 into multiple sheet-like stones with a thickness of no more than 300mm.

[0090] After all drilling operations are completed, use drill rods or grouting pipes to inject grout (such as ordinary silicate cement grout with a water-cement ratio of 1:1, or cement-water glass double-liquid grout) into all rows of holes 5 to seal the holes.

[0091] During shield tunneling, the shield cutterhead is used to cut through the 5th hole and the sheet-like rocks together.

[0092] When the net spacing between pipelines at the construction site is narrow, large rotary drilling equipment cannot enter the site, and conventional blasting is strictly prohibited, the preferred method for treating boulder 1 is to use multiple rows of boreholes 5. These boreholes 5 divide boulder 1 into sheet-like stones no thicker than 300mm, making them easily crushed or overturned and cut off by the thrust and cutting force of the tunnel boring machine (TBM). After drilling, grouting is performed to seal the boreholes, filling the cavities left by the boreholes 5 and providing appropriate filling and constraint for the sheet-like stones. During TBM tunneling, the TBM cutterhead can cut through the grout-sealed boreholes 5 and the sheet-like stones together, improving construction efficiency.

[0093] Furthermore, when the diameter d of boulder 1 satisfies d < 500 mm, the fifth type of boulder treatment procedure (grouting reinforcement method) is adopted, such as... Figure 9 , Figure 10 As shown, it includes: Multiple rows of grouting holes 6 are drilled vertically downwards from the ground using a drilling and grouting rig (or a geological drilling rig). The multiple rows of grouting holes 6 are preferably spaced 2.0m apart in the plane. A 2.0m plum blossom-shaped grid is used for dot matrix arrangement.

[0094] To ensure that the boulder 1 and the surrounding disturbed soil are completely and firmly encased, the spatial range of the grouting holes 6 is controlled as follows: Planar range: such as Figure 9 , Figure 10As shown, the grouting holes 6 are arranged in a plane covering an area of ​​at least 2.5m radially around the boulder 1 and extending at least 5m along the front of the tunnel boring machine. Depth range: such as Figure 10 As shown, the drilling depth of grouting hole 6 extends to at least 2.5m below the bottom elevation of boulder 1.

[0095] After the borehole reaches the target depth, a retractable drilling and grouting machine is used to perform segmented pressure grouting from the bottom of the hole upwards: The grouting slurry uses a cement-water glass two-component slurry. The cement slurry uses P.O42.5 ordinary Portland cement (water-cement ratio of 1:1), and the water glass uses 40°Bé water glass (diluted with water at a mass ratio of 1:1). During injection, the cement slurry and water glass solution are mixed at a volume ratio of 1:1.

[0096] Grouting begins at the deepest point, with the drill rod gradually raised upwards in 50cm increments, and the grouting control pressure is set to no more than 0.5MPa.

[0097] In the soil layers around and above and below the boulder 1, the grout seeps into and diffuses into the surrounding soil under a pressure of 0.5 MPa (the grout diffusion radius is about 0.7 m). After the cement grout solidifies, a three-dimensional grouting consolidation zone 7 is formed around the boulder 1, and the boulder 1 is locked in the grouting consolidation zone 7.

[0098] During shield tunneling, the shield cutterhead is used to cut the grouting consolidation area 7 and the isolated rocks 1 inside it.

[0099] For the small-diameter boulder 1, the costly and complex method of in-situ rock breaking was abandoned. Instead, an integral grouting reinforcement method was adopted. Grouting reinforced the strata surrounding the boulder 1, forming a grouting consolidation zone 7, which encapsulated the small boulder 1 within the grouting consolidation zone 7. Furthermore, the grouting consolidation zone 7 extended at least 5 meters along the tunnel boring machine's (TBM) advance, using the consolidation body to provide positive thrust resistance to the boulder 1, preventing it from escaping or rolling forward during cutterhead cutting. During TBM tunneling, the cutterhead could directly cut through the grouting consolidation zone 7 and the small boulder 1 within it, improving construction efficiency.

[0100] Furthermore, when the net spacing D of pipelines at the construction site satisfies: 110mm ≤ D < 150mm, and the permissible seismic safety velocity threshold V at the construction site is < 1.0cm / s, the sixth type of boulder treatment step (deep-hole fracturing method) is adopted, such as... Figure 11 , Figure 12 As shown, it includes: Using a lightweight geological drilling rig or down-the-hole drilling rig, multiple split holes 8 are drilled vertically from the ground to the underground boulder 1.

[0101] like Figure 11As shown, within the planar projection area of ​​boulder 1, multiple splitting holes 8 are arranged in a ring-shaped combined layered lattice pattern with the geometric center of boulder 1 as the center.

[0102] Layer spacing control: Concentric rings expand layer by layer from the inside out, controlling the radius difference between adjacent concentric rings (i.e., layer spacing). Figure 11 The mid-range distance (L1) is 400mm; Circumferential spacing control: On the same concentric ring, each splitting hole 8 is arranged at equal intervals along the circumferential direction, and the circumferential arc length spacing between adjacent splitting holes 8 is controlled to be 500~800mm. Figure 11 Mid-range L2).

[0103] like Figure 12 As shown, the split holes 8 are drilled with differentiated diameters and depths from top to bottom: Upper guide section: From the ground surface to the upper surface of boulder 1, drill a pilot hole with a diameter of 110mm, and follow the hole with PVC casing to protect the wall, so as to prevent the overlying soil or soft rock from collapsing and blocking the hole. Rock-breaking section inside the boulder: Drill downwards from the upper surface of boulder 1 into the interior of boulder 1, and drill a 90mm diameter pilot hole inside the boulder (no need to install a PVC sleeve). After the inspection and cleaning of splitting hole 8 is completed, the high-pressure hydraulic splitting rod 9 is slowly lowered into the pilot hole section inside boulder 1 using ground-based mechanical hoisting equipment and extended high-pressure oil pipes. The high-pressure oil pipe is led out from the hole to the ground and connected to the high-pressure hydraulic pump station located on the ground. The ground high-pressure hydraulic pump station is started, and splitting is carried out in stages according to the order of first the outer ring holes, then the middle inner ring holes, and finally the center hole: the pump station outputs high-pressure oil (working pressure ≥60MPa), driving the wedge mechanism inside the splitting rod 9 to expand laterally in all directions, generating a tension force of up to several thousand tons (e.g., ≥3000t for a single rod); the rated high pressure is maintained for 30~60s, causing boulder 1 to split along the annular array of holes; this process is repeated until the width of the through crack in boulder 1 expands to at least 5cm.

[0104] After the expansion and cracking of boulder 1 is completed, the splitting rod 9 is removed. A retractable drilling and grouting machine is used to inject grout (such as a two-component grout prepared by mixing ordinary Portland cement with 40°Bé water glass in a 1:1 volume ratio, with a grouting control pressure ≤0.5MPa) into the expanded cracks and ducts of boulder 1 through the splitting hole 8. After the grout solidifies, it binds the split fragments into a cohesive composite body that is easy to cut.

[0105] During shield tunneling, the shield cutterhead is used to cut the grout-consolidated fragments.

[0106] When the net spacing between pipelines at the construction site is extremely close, and conventional blasting is strictly prohibited, the deep-hole fracturing method is preferred for treating boulder 1. The expansion force generated by the hydraulic fracturing rod 9 destroys and disintegrates the overall structure of boulder 1. After fracturing, grout is injected into the fracturing hole 8 and the internal cracks of boulder 1 to fill the cavities created by the fracturing and cement the fracturing fragments, thus re-locking the discrete fragments into a softer, more easily cuttable whole. During shield tunneling, the cutterhead can directly cut through the grout-bonded fracturing fragments, improving construction efficiency.

[0107] In addition to the six types of isolated rock handling steps mentioned above, if the ground conditions at the construction site are completely unsuitable for equipment to enter and pre-treat, or if an isolated rock 1 in a blind zone not revealed by geological supplementary exploration is encountered during the tunnel boring machine's excavation, a seventh type of isolated rock handling step (opening the compartment to handle the isolated rock) can be used as a backup plan. Specifically, it includes the following steps: Before opening the excavation chamber, to ensure the stability of the excavation chamber and the working face, cement-water glass double-liquid grout is injected into the soil in front of and around the cutterhead through the surface or the grouting holes of the tunnel boring machine for reinforcement. At the same time, double-liquid grout or bentonite sealing rings are installed at the tail of the shield, and high-viscosity sodium-based bentonite slurry (funnel viscosity 80~120s) is injected into the soil chamber. By controlling the pressure inside the chamber, a high-density supporting mud film is established at the working face to ensure that no instability or water inrush occurs at the working face during pressurized or atmospheric pressure excavation.

[0108] After opening the compartment and ensuring the interior environment is safe, the workers enter the excavation compartment: Using the existing air supply pipeline in the cabin, a miniature handheld pneumatic rock drill (such as the Y6 handheld rock drill) is connected to the surface of the isolated rock 1 in the cutterhead area or soil chamber, and multiple small-diameter pilot holes are arranged in a plum blossom pattern. The silent expanding agent (static breaking agent) slurry, prepared according to the preset water-cement ratio, is filled and compacted into the pilot hole within 10 minutes. The silent expanding agent undergoes a hydration reaction in the hole, generating expansion pressure. Under safe conditions with no noise, no vibration, no flying stones, and no harmful gases, the boulder 1 is statically expanded and broken into small stones with a particle size ≤300mm after 4~24 hours.

[0109] After the pre-fracture of boulder 1 is completed, personnel exit the tunnel and close the chamber, resuming normal tunneling. The shield cutterhead rotates and crushes the pre-fractured boulder fragments, further grinding them and discharging them through the shield machine's screw conveyor / soil pump, ensuring continuous tunneling.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for handling isolated boulders during shield tunneling construction, characterized in that, Includes the following steps: S1. Conduct supplementary geological exploration to obtain parameters of the isolated rock (1) and environmental parameters of the construction site; S2. Based on the geological survey, the isolated boulders (1) at the construction site were classified and treated accordingly: When the diameter d of the boulder (1) satisfies: d≥500mm, and the net spacing D of pipelines at the construction site satisfies: 250mm≤D<1400mm, and the allowable seismic safety velocity threshold V at the construction site is <1.0cm / s, the first type of boulder treatment steps are adopted, including: Drill a hole from the ground down, drill through the boulder (1) located within the tunnel body, and continue drilling down to a predetermined depth below the boulder (1) to form an anchoring hole that penetrates the boulder (1); (2) Lower the fiberglass reinforcement cage into the anchor hole. Concrete is poured into the anchoring hole to form an anchoring pile (3) that penetrates the boulder (1), and the boulder (1) is anchored and bound by the anchoring pile (3). During shield tunneling, the shield cutterhead is used to cut the boulder (1) and the anchor pile (3) together.

2. The method for handling isolated boulders during shield tunneling construction according to claim 1, characterized in that, In the first type of isolated rock treatment step, continue drilling downward to a predetermined depth below the isolated rock (1), including: continuing to drill downward to at least 2m below the bedrock surface below the isolated rock (1), and the bottom elevation of the anchor hole is located at no less than 1m below the bottom elevation of the tunnel.

3. The method for handling isolated boulders during shield tunneling construction according to claim 1, characterized in that, In the first type of isolated rock treatment steps, the diameter of the pilot hole is 250mm, and the top of the anchor pile (3) is 500mm lower than the ground elevation.

4. The method for handling isolated boulders during shield tunneling construction according to claim 1, characterized in that, In the first type of isolated rock treatment steps, when the diameter d of the isolated rock (1) satisfies 1m≤d<2m, the number of anchor holes is 1; When the diameter d of the boulder (1) satisfies 2m≤d<3m, the number of anchor holes is 2; When the diameter d of the boulder (1) satisfies 3m≤d<4m, the number of anchor holes is 4; When the diameter d of the boulder (1) satisfies 4m≤d<5m, the number of anchor holes is 6; When the diameter d of the boulder (1) satisfies 5m≤d≤6m, the number of anchor holes is 8.

5. The method for handling isolated boulders during shield tunneling construction according to claim 1, characterized in that, In S2, when the permissible seismic safety velocity threshold V at the construction site is ≥1.0 cm / s, the second type of boulder treatment procedure is adopted, including: Within the area of ​​the isolated rock (1), blasting holes (4) are drilled, and multiple rows of blasting holes (4) are arranged in a dot matrix pattern with a hole spacing and row spacing of no more than 0.75m. When detonating, the blasting holes (4) located at the edge of the boulder (1) are detonated first, and then the blasting holes (4) located in the middle of the boulder (1) are detonated one by one. After the blasting is completed, holes are drilled and grout is injected into the blasting area to consolidate the blasted fragments; During shield tunneling, the shield cutterhead is used to cut the grout-consolidated explosive fragments.

6. The method for handling isolated boulders during shield tunneling construction according to claim 5, characterized in that, In the second type of isolated rock treatment steps, among two adjacent blasting holes (4), one blasting hole (4) is drilled to the bottom surface of the isolated rock (1) and explosives are loaded from the bottom of the hole to a distance of 10cm from the top surface of the isolated rock (1); the bottom of the other blasting hole (4) is 10cm from the bottom surface of the isolated rock (1) and explosives are loaded from the bottom of the hole to a distance of 10cm from the top surface of the isolated rock (1).

7. The method for handling isolated boulders during shield tunneling construction according to claim 1, characterized in that, In S2, when the net spacing between pipelines at the construction site D ≥ 1400 mm and the permissible seismic safety velocity threshold V < 1.0 cm / s, the third type of boulder treatment procedure is adopted, including: Install steel casing; Rotary drilling rigs are used to drill through the boulder (1) and drill downwards to at least 1m below the bottom elevation of the shield tunnel; After drilling, the hole is cleaned to remove the debris of the boulder (1), and then mortar is used to backfill the rotary drilling hole to the ground to form a pile. During shield tunneling, the shield cutterhead is used to cut rotary piles.

8. The method for handling isolated boulders during shield tunneling construction according to claim 1, characterized in that, In S2, when the net spacing D between pipelines at the construction site satisfies: 150mm ≤ D < 250mm, and the permissible seismic safety velocity threshold V at the construction site is < 1.0cm / s, the fourth type of boulder treatment steps are adopted, including: Using a drilling rig, multiple rows of holes (5) are drilled. The extension direction of each row of holes (5) is parallel to the centerline of the shield tunnel. The holes (5) are drilled to at least 1m below the bottom elevation of the shield tunnel. The spacing between the rows of holes (5) is no more than 400mm. The boulder (1) is cut and separated into multiple sheet-like stones with a thickness of no more than 300mm. After drilling is completed, grouting and sealing operations are carried out on the borehole (5); During shield tunneling, the shield cutterhead is used to cut the drainage holes (5) and the sheet-like rocks together.

9. A method for handling isolated boulders during shield tunneling construction according to claim 1, characterized in that, In S2, when the diameter d of the boulder (1) satisfies d < 500 mm, the fifth type of boulder treatment steps are adopted, including: Multiple rows of grouting holes (6) are drilled on the ground using a drilling rig. The planar range of the grouting holes (6) covers an area of ​​at least 2.5m radially outward from the boulder (1) and at least 5m along the tunnel boring direction. The depth of the grouting holes (6) extends at least 2.5m below the bottom of the boulder (1). After drilling is completed, grout is injected from the bottom of the hole upwards to consolidate and reinforce the strata in the area of ​​the isolated rock (1) and form a grouting consolidation area (7). During shield tunneling, the shield cutterhead is used to cut the grouting consolidation area (7) and the isolated rocks (1) inside it.

10. A method for handling isolated boulders during shield tunneling construction according to claim 1, characterized in that, In S2, when the net spacing D between pipelines at the construction site satisfies: 110mm ≤ D < 150mm, and the permissible seismic safety velocity threshold V at the construction site is < 1.0cm / s, the sixth type of boulder treatment procedure is adopted, including: Multiple splitting holes (8) were drilled in the boulder (1) using a ring-combined layered method, with the spacing between adjacent layers controlled at 400 mm and the circumferential spacing of each splitting hole (8) being 500~800 mm. After the splitting hole (8) is drilled, the splitting rod (9) is lowered into the splitting hole (8) and pressure is applied to expand the boulder (1) until the width of the crack in the boulder (1) expands to at least 5 cm. After the expansion and cracking are completed, grout is injected into the split hole (8) to consolidate the split fragments; During shield tunneling, the shield cutterhead is used to cut the grout-consolidated fragments.

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