Construction method of double-shield open-type TBM (Tunnel Boring Machine) during cavity collapse of unfavorable geological section

Abstract

The invention relates to the technical field of TBM tunnel construction, in particular to a construction method of a double-shield open-type TBM during cavity collapse of an unfavorable geological section, which comprises the following steps: firstly, carrying out geological judgment, then quickly constructing a primary support structure to form a closed operation space, and then quickly backfilling a collapsed cavity by using a foaming chemical material to form a closed operation space; and a reinforcing chemical material is used for rapidly consolidating the accumulated surrounding rock above the TBM shield, and finally, the formed primary support structure is subjected to grouting reinforcement, so that the primary support structure is tightly combined with the surrounding rock. According to the method, the unfavorable geological section is judged in advance, the front geological condition is mastered in advance, response is conducted in advance, the vault space is constructed, the excavated tunnel section is rapidly stabilized, the surrounding rock is prevented from further chipping, then the stability of the surrounding rock above the TBM equipment is enhanced through chemical irrigation backfilling and chemical irrigation consolidation, the shield body is prevented from being directly threatened by broken stones or collapsed blocks, and the construction efficiency is improved. And finally, grouting reinforcement is conducted on the primary supporting structure, so that the supporting structure and the surrounding rock form a tightly-combined whole.

Description

Technical Field

[0001] The present invention relates to the technical field of TBM tunnel construction, and particularly relates to a construction method for a double-shield open TBM in a cavity collapse section of poor geological conditions. Background Art

[0002] A TBM (Tunnel Boring Machine) is a complete set of automated tunnel excavation equipment integrating technologies such as machinery, electronics, hydraulics, and control. Its tunnel excavation construction has the technical characteristics of being fast, efficient, high-quality, safe, and environmentally friendly, and has been widely used in the construction of tunnel projects such as water conservancy and hydropower, transportation, and municipal engineering.

[0003] However, during the TBM tunneling process, especially in long-distance or tunnel projects with complex geological conditions, various poor geological conditions are often encountered, such as fault fracture zones, soft surrounding rocks, water-rich areas, etc. Among them, sudden water inrush and surrounding rock collapse (forming a cavity) are common major geological disasters.

[0004] Once significant water inrush or cavity collapse occurs during the TBM tunneling process, it not only causes construction delays, greatly increases project costs, endangers the lives of construction workers and the safety of TBM equipment, but also poses potential quality hazards to the project, brings great difficulties to the maintenance work, and even makes the tunnel unable to be used normally. When the TBM tunnels through poor geological sections, collapses often occur due to extremely broken surrounding rocks, which are extremely difficult to handle and cause delays in the TBM construction period. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a construction method for a double-shield open TBM in a cavity collapse section of poor geological conditions, which can quickly handle the water inrush and collapse section in a timely manner, and makes the treated water inrush and collapse area have better stability, and is applicable to the construction method of the TBM poor geological section with a small cross-section.

[0006] The present invention is realized through the following technical solutions:

[0007] A construction method for a double-shield open TBM in a cavity collapse section of poor geological conditions, including:

[0008] Conduct poor geological judgment to determine the surrounding rock conditions, water inrush, and collapse risks in front of the tunnel face;

[0009] Install steel arch frames in the excavated section as part of the initial support structure;

[0010] Install longitudinal steel bar rows and transverse steel bar rows, and the transverse steel bar rows, longitudinal steel bar rows and steel arch frames form a top arch space;

[0011] Carry out rapid chemical grouting backfill for the water inrush and cavity collapse area to fill the cavity and initially stabilize the surrounding rock;

[0012] Chemically grout and consolidate the loose crushed stone area above the TBM shield to form a stable load-bearing structure;

[0013] Grout and reinforce the initial support structure composed of steel arch frames, longitudinal steel bar rows, and transverse steel bar rows to form an integral body with the surrounding rock.

[0014] Specifically, the methods for determining poor geology include:

[0015] Analyze the tunneling parameters to determine the strength of the surrounding rock and whether the face collapses. The tunneling parameters include thrust, muck output, cutterhead torque, cutterhead rotation speed, and tunneling speed;

[0016] Observe and analyze the muck aggregates to judge the sand content, mud content, water content of the surrounding rock, and the strength of the surrounding rock;

[0017] Combine the results of advanced geological forecasting to obtain a geological report on poor geological conditions, disaster geological conditions, fault structure information, location information of fault fracture zones, property information, filling material state information, water inrush state information, and groundwater state information.

[0018] Specifically, the methods for installing steel arch frames include:

[0019] Set the steel arch frames between the TBM shield and the tunnel wall, and continuously install them from the set starting position to the tail of the TBM shield;

[0020] Install a steel bar mesh on the back of the steel arch frame, and spray concrete on the inner arc surface of the steel arch frame to enclose the installed steel arch frames to form an integral body.

[0021] Specifically, the methods for installing longitudinal steel bar rows include: position and store the longitudinal steel bar rows through the steel bar grooves reserved at the top of the TBM strut shield, weld one end of the longitudinal steel bar rows to the steel arch frame, and extend the other end of the longitudinal steel bar rows out of the shield along with the TBM tunneling and contact the tunnel wall;

[0022] The methods for installing transverse steel bar rows include: drive the steel bars constituting the transverse steel bar rows into the side wall of the tunnel from between the steel arch frame and the TBM shield until they reach hard rock. One end of the transverse steel bar rows is fixed in the hard rock, and the other end of the transverse steel bar rows is connected to the longitudinal steel bar rows and the steel arch frame;

[0023] Among them, the central axis of the steel bars of the longitudinal steel bar rows is parallel to the central axis of the tunnel, and the central axis of the steel bars of the transverse steel bar rows is perpendicular to the central axis of the tunnel.

[0024] Specifically, the methods for quickly chemically grouting and backfilling the water inrush and collapse cavity area include:

[0025] Insert one end of multiple grouting pipes through the steel arch frame and insert them through the loose crushed stone area into the water inrush and collapse cavity area;

[0026] Inject foaming chemical materials from the other end of the grouting pipe into the water-inrush and cavity-collapse area until the entire water-inrush and cavity-collapse area is filled, preliminarily stabilizing the surrounding rock.

[0027] Specifically, the method for chemically grouting and consolidating the loose gravel area includes:

[0028] Pierce one end of multiple rows of grouting pipes through the steel arch and insert them into the loose gravel area;

[0029] Inject reinforcing chemical materials from the other end of the grouting pipe into the loose gravel area until a stable bearing structure is formed.

[0030] Specifically, the grouting reinforcement of the primary support structure includes:

[0031] Use single-fluid grout and double-fluid grout to grout the surrounding rock behind the steel arch; among them, the single-fluid grout is cement grout, and the double-fluid grout is a mixed slurry of cement and water glass.

[0032] Furthermore, the method further includes:

[0033] Use a total station to observe the settlement rate of the steel arch, and use a ground penetrating radar or core drilling to check and confirm the effect of surrounding rock grouting reinforcement.

[0034] Furthermore, the method further includes:

[0035] After the TBM tunnels through the poor geological section, add temporary steel supports in the core section of the cavity to strengthen the primary support structure. The lower end of the temporary steel support is fixed to the tunnel floor through a backing plate, and the upper end of the temporary steel support is fixed to the steel arch.

[0036] Furthermore, after the TBM tunneling is completed, add a reinforced concrete lining on the basis of the primary support structure and remove the temporary steel supports.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] The present invention first conducts geological determination; then quickly constructs a primary support structure to form a closed working space; then, uses foaming chemical materials to quickly backfill the cavity of the cavity-collapse, and uses reinforcing chemical materials to quickly consolidate the accumulated surrounding rock above the TBM shield; finally, grouts and reinforces the formed primary support structure to make it closely combined with the surrounding rock.

[0039] By judging the poor geological section in advance, the present invention can master the geological conditions ahead in advance, take countermeasures in advance, construct the vault space, quickly stabilize the excavated tunnel section, prevent further caving of the surrounding rock, and then enhance the stability of the surrounding rock above the TBM equipment through chemical grouting backfill and chemical grouting consolidation to prevent gravel or collapsed blocks from directly threatening the shield body. Finally, by grouting and reinforcing the primary support structure, the support structure and the surrounding rock form a closely integrated whole, improving the bearing capacity and overall stability of the support system, and ensuring the long-term safety and reliability of the tunnel structure after treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings illustrate exemplary embodiments of the present invention and are used together with the description to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention, and the drawings are included in this specification and form a part of this specification, and do not constitute a limitation on the embodiments of the present invention.

[0041] Figure 1 It is a sectional view of the support system after constructing the vault space in a construction method of a double-shield open TBM in a cavity collapse in a poor geological section according to the present invention.

[0042] Figure 2 It is a schematic diagram of quickly chemically grouting and backfilling the water-inrush cavity collapse area according to the present invention.

[0043] Figure 3 It is a schematic diagram of chemically grouting and consolidating the loose gravel area according to the present invention.

[0044] Figure 4 It is a schematic diagram of the temporary steel support according to the present invention.

[0045] Reference numerals in the drawings: 1 - longitudinal steel bar row, 2 - transverse steel bar row, 3 - steel arch frame, 4 - steel bar mesh, 5 - temporary steel support, 6 - backing plate, 10 - water-inrush cavity collapse area, 11 - multiple grouting pipes, 20 - loose gravel area, 21 - multiple rows of grouting pipes. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the relevant content and do not limit the present invention.

[0047] In addition, it should be noted that only parts related to the present invention are shown in the drawings for the convenience of description.

[0048] In this application, unless otherwise clearly defined and limited, terms such as "installation", "connection", "attachment", "fixation", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a direct connection, or an indirect connection through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0049] In this application, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0050] Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0051] Embodiment 1

[0052] This embodiment provides a systematic construction method for dealing with poor geological sections (sections with cavity collapse and possible water gushing) during the construction process using a double-shield open-type tunnel boring machine (TBM). The solution of this embodiment is based on accurately judging the geological risks ahead. First, a temporary initial support structure is quickly constructed to ensure the operation safety. Then, chemical grouting treatments are respectively carried out on the cavity collapse and the potentially unstable areas above the TBM equipment. Finally, the initial support structure is reinforced so that it can stably bear the formation pressure, thereby ensuring that the TBM can pass through the poor geological section safely and smoothly. The specific construction method of the double-shield open-type TBM when there is a cavity collapse in the poor geological section includes:

[0053] Carry out poor geological determination to determine the surrounding rock conditions, water gushing and collapse risks in front of the heading face, including judging the stability of the surrounding rock (referring to the rock mass or soil body around the tunnel), whether there is or potentially there is water gushing phenomenon, and the possibility and risk degree of collapse (forming a cavity).

[0054] Install steel arch 3 in the excavated section as part of the initial support structure, that is, a part of the temporary or partial permanent support constructed after excavation, used to provide preliminary bearing capacity and prevent the surrounding rock in the excavated section from further deforming or becoming unstable.

[0055] Install the longitudinal steel bar row 1 and the transverse steel bar row 2. The transverse steel bar row 2, the longitudinal steel bar row 1 and the steel arch frame 3 form a relatively closed and stable structural space - the crown arch space at the top of the tunnel.

[0056] Quickly carry out chemical grouting backfill for the water gushing and cavity collapse area 10 to fill the cavity and preliminarily stabilize the surrounding rock. The water gushing and cavity collapse area 10 is a cavity area formed by collapse. Chemical grouting uses chemical slurry to expand in the cavity, fill the cavity of the collapsed cavity, preliminarily stabilize the surrounding rock around the cavity, and prevent the collapse range from continuing to expand.

[0057] Carry out chemical grouting consolidation for the loose gravel area 20 above the TBM shield to form a stable bearing structure. Consolidation means injecting slurry to cement and harden the loose particles to form a stable bearing structure with a certain strength and integrity to eliminate the risk of falling blocks above the TBM.

[0058] Carry out grouting reinforcement for the primary support structure composed of the steel arch frame 3, the longitudinal steel bar row 1 and the transverse steel bar row 2 to form an integral with the surrounding rock. It means injecting slurry into the gap between the primary support structure and the surrounding rock to closely combine the support structure and the surrounding rock into an integral.

[0059] Embodiment 2

[0060] This embodiment provides a specific construction method, taking a double - shield open - type TBM with a diameter of 3.53 meters as an example.

[0061] Step 1, the methods for judging bad geology include:

[0062] Analyze the tunneling parameters to judge the strength of the surrounding rock and whether the face collapses. The tunneling parameters include thrust, mucking volume, cutterhead torque, cutterhead rotation speed and tunneling speed;

[0063] Observe and analyze the mucked aggregate to judge the sand content, mud content, water content of the surrounding rock and the strength of the surrounding rock;

[0064] Combine the results of advanced geological forecasting to obtain a geological report on bad geological conditions, disaster geological conditions, fault structure information, location information of fault fracture zones, property information, filling state information, water gushing state information, and groundwater state information.

[0065] Determine the surrounding rock strength of the tunnel face by the magnitude of the thrust in the tunneling parameters. The thrust is directly proportional to the surrounding rock strength of the tunnel face. The greater the thrust, the harder the surrounding rock. Generally, when the thrust is below 2500 kN, the surrounding rock is broken and prone to collapse. Determine whether the tunnel face collapses by observing the muck output, cutterhead torque and rotation speed, and tunneling speed. If it is observed that the muck output is large and remains unchanged, the cutterhead torque and rotation speed are high, and the tunneling speed is small, it can be determined that the surrounding rock of the tunnel face has collapsed. Determine whether the surrounding rock of the tunnel face contains mud, sand, water content and the surrounding rock strength by observing the composition of the muck and knocking on the stones in the muck. When necessary, samples can be taken for strength tests. Combine with advanced geological forecasts such as TXT or ground penetrating radar to finally obtain a geological report on the specific conditions of adverse and disaster geology, the location, nature, filling state of the fault structure and fault fracture zone, and the water inrush and groundwater state.

[0066] Step two, the method for installing the steel arch 3 includes:

[0067] Set the steel arch 3 between the TBM shield and the tunnel wall, and continuously install it from the set starting position to the tail of the TBM shield;

[0068] Install the steel mesh 4 on the back of the steel arch 3, and spray concrete on the inner arc surface of the steel arch 3 to enclose the installed steel arch 3 to form a whole.

[0069] Adopt I12 and below I-beams to continuously install the steel arch 3 from the position with better surrounding rock to the tail of the TBM shield. First, adopt I12 I-beams to continuously install the steel arch 3 from the position with better surrounding rock to the tail of the TBM shield. According to the spacing of 30 cm to 50 cm, use the jacking device to install the steel arch 3 in place. At the same time, install the steel mesh 4 on the back of the steel arch 3, and spray C30 concrete to the inner arc surface of the steel arch 3 to enclose the installed steel arch 3 to form a whole.

[0070] Step three, the method for installing the longitudinal steel bar row 1 includes: position and store the longitudinal steel bar row 1 through the steel bar groove reserved at the top of the TBM tightening shield, weld one end of the longitudinal steel bar row 1 to the steel arch 3, and extend the other end of the longitudinal steel bar row 1 out of the shield along with the TBM tunneling and contact with the tunnel wall.

[0071] Install the φ16 longitudinal steel bar row 1 using the steel bar groove reserved at the top of the TBM tightening shield, with a spacing of no more than 5 cm. One end is connected to the steel arch 3, and the other end gradually extends out of the shield along with the TBM tunneling. The outside of the steel bar row extending out of the shield contacts the tunnel wall, and the inside is welded and fixed to the steel arch 3 to achieve continuous closure at the top, prevent rock materials from directly sliding to the installation area of the steel arch 3 from the top, and ensure construction safety.

[0072] When necessary, a temporary steel support 5 can be added in the middle of the longitudinal steel bar row 1. The steel bar row and the temporary steel support 5 can slide freely, and the temporary steel support 5 is welded and fixed to the TBM connection bridge, moving with the TBM.

[0073] The method for installing the transverse steel bar row 2 includes: driving the steel bars forming the transverse steel bar row 2 between the steel arch 3 and the TBM shield into the side wall of the tunnel until reaching hard rock. One end of the transverse steel bar row 2 is fixed in the hard rock, and the other end of the transverse steel bar row 2 is connected to the longitudinal steel bar row 1 and the steel arch 3.

[0074] Use a rammer to drive φ22 steel bars into the side wall of the tunnel between the steel arch 3 and the shield at intervals of 5 - 10 cm, passing through the broken surrounding rock and hammering into the hard rock. The other end forms a closed top arch space with the steel bar row, the steel arch 3, the shield, etc., preventing large pieces of fallen slag from the top from falling behind the equipment and creating favorable conditions for continuous construction.

[0075] Among them, the central axis of the steel bars in the longitudinal steel bar row 1 is basically parallel to the central axis of the tunnel, and the central axis of the steel bars in the transverse steel bar row 2 is basically perpendicular to the central axis of the tunnel. As Figure 1 shown, the construction of the initial support structure is completed.

[0076] Step four, the method for quickly chemically grouting and backfilling the water - gushing collapse cavity area 10 includes:

[0077] One end of multiple grouting pipes 11 penetrates through the steel arch 3 and is inserted into the water - gushing collapse cavity area 10 through the loose gravel area 20;

[0078] Inject a foaming chemical material from the other end of the grouting pipe into the water - gushing collapse cavity area 10 until the entire water - gushing collapse cavity area 10 is filled, initially stabilizing the surrounding rock.

[0079] As Figure 2 shown, use a non - toxic and flame - retardant polyurethane - like foaming material to quickly grout and fill the collapsed cavity space, fully and densely seal the surface of the surrounding rock in the collapse cavity and expand and squeeze into the fissures or defect areas on the surface of the surrounding rock to stabilize the surrounding rock so that it no longer flakes or collapses.

[0080] Step five, the method for chemically grouting and consolidating the loose gravel area 20 includes:

[0081] One end of multiple rows of grouting pipes 21 penetrates through the steel arch 3 and is inserted into the loose gravel area 20;

[0082] Inject a reinforcing chemical material from the other end of the grouting pipe into the loose gravel area 20 until a stable load - bearing structure is formed.

[0083] As Figure 3As shown in the figure, a polyether-based reinforced chemical material is adopted to quickly grout and consolidate the broken surrounding rock accumulated above the shield, so that the broken rock mass is quickly cemented into an integral load-bearing body, restoring the overall load-bearing function, forming a consolidated surrounding rock arch ring support system with a certain thickness, achieving that during the forward movement of the TBM shield, no large amount of slag falls from the shield, avoiding affecting the construction effect of Step 5, and ensuring construction safety.

[0084] Step 6, grouting and strengthening the initial support structure includes:

[0085] Injecting grout into the surrounding rock on the back of the steel arch 3 using single-component grout and two-component grout; among them, the single-component grout is cement grout, and the two-component grout is a mixed grout of cement and water glass.

[0086] Strengthening the initial support structure is to use single-component grout and two-component grout to reinforce the surrounding rock on the back of the steel arch 3 to form an integral, and the grouting pressure is 0.1 - 1 MPa; among them, the single-component grout is cement grout, and the two-component grout is formed by mixing cement and water glass in a ratio of 1:2.

[0087] Example 3

[0088] In addition, to ensure that the construction quality reaches the expected effect, the method further includes:

[0089] Observing the settlement rate of the steel arch 3 using a total station, and using ground-penetrating radar or core drilling to check and confirm the effect of surrounding rock grouting reinforcement. As a new high-resolution, high-efficiency non-destructive high-tech detection technology, ground-penetrating radar has characteristics such as safety, convenience, and speed.

[0090] After the TBM tunnels through the poor geological section, a temporary steel support 5 is added in the core section of the collapse cavity to strengthen the initial support structure. The lower end of the temporary steel support 5 is fixed to the tunnel floor through a backing plate 6, and the upper end of the temporary steel support 5 is fixed to the steel arch 3.

[0091] After the TBM tunnels through, a reinforced concrete lining is added on the basis of the initial support structure, and the temporary steel support 5 is removed.

[0092] After the TBM tunnels through the poor geological section, a temporary steel support 5 is added in the core section of the collapse cavity to strengthen the impact stability of the steel arch 3 system and improve safety, and it is gradually removed during the later pouring of the reinforced concrete lining; after the TBM tunnels through, a reinforced concrete lining with a thickness not greater than 50 cm is added on the basis of the steel arch 3 support system.

[0093] In the description of this specification, the description with reference to terms such as "one embodiment / way", "some embodiments / ways", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of this application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments / ways or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments / ways or examples described in this specification and the features of different embodiments / ways or examples.

[0094] In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0095] Those skilled in the art should understand that the above embodiments are only for clearly explaining the present invention and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications can be made on the basis of the above invention, and these changes or modifications are still within the scope of the present invention.

Claims

1. A construction method of a double-shield open TBM in a poor geological section with a collapsed cavity, characterized in that: include: Conduct adverse geological assessment to determine the surrounding rock conditions, water inrush and landslide risks in front of the tunnel face; Install steel arches as part of the initial support structure in the excavated section; Install longitudinal and transverse steel bars, which form a top arch space with the steel arch frame; Rapid chemical grouting backfill is carried out in the water-gushing collapse cavity area to fill the cavity and initially stabilize the surrounding rock; Chemical grouting is performed on the loose gravel area above the TBM shield to form a stable load-bearing structure; The initial support structure consisting of steel arch frames, longitudinal steel bars and transverse steel bars is reinforced by grouting to form a whole with the surrounding rock.

2. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 1, characterized in that: Methods for making adverse geological determinations include: Analyze the excavation parameters to determine the surrounding rock strength and whether the tunnel face has collapsed. The excavation parameters include thrust, slag discharge, cutterhead torque, cutterhead speed and excavation speed. Observe and analyze slag aggregates to determine the sand content, mud content, water content and strength of surrounding rocks; Combined with the results of advanced geological forecasting, obtain geological reports on adverse geological conditions, disastrous geological conditions, fault structure information, fault fracture zone location information, property information, filling status information, water gushing status information and groundwater status information.

3. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 1, characterized in that: Methods for installing steel arches include: The steel arch is set between the TBM shield and the tunnel wall, and is installed continuously from the set starting position to the tail of the TBM shield; A steel mesh is installed on the back of the steel arch frame, and concrete is sprayed on the inner curved surface of the steel arch frame to seal the installed steel arch frame into a whole.

4. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 1, characterized in that: The method for installing the longitudinal steel bar row includes: positioning and storing the longitudinal steel bar row through the steel bar groove reserved at the top of the TBM support shield, extending one end of the longitudinal steel bar row and welding and fixing it to the steel arch frame, and extending the other end of the longitudinal steel bar row outside the shield as the TBM excavates and contacts the tunnel wall; The method for installing the transverse reinforcement row includes: driving the reinforcements constituting the transverse reinforcement row from between the steel arch frame and the TBM shield into the tunnel side wall until they are in the hard rock, fixing one end of the transverse reinforcement row in the hard rock, and connecting the other end of the transverse reinforcement row to the longitudinal reinforcement row and the steel arch frame; Among them, the central axis of the steel bars in the longitudinal steel bar row is parallel to the central axis of the tunnel, and the central axis of the steel bars in the transverse steel bar row is perpendicular to the central axis of the tunnel.

5. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 1, characterized in that: The methods for rapid chemical grouting backfilling of water-gushing collapse areas include: One end of a plurality of grouting pipes is passed through the steel arch frame and inserted into the water gushing collapse cavity area through the loose gravel area; Foaming chemical materials are injected into the water gushing and collapsing cavity area from the other end of the grouting pipe until the entire water gushing and collapsing cavity area is filled to initially stabilize the surrounding rock.

6. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 1, characterized in that: Methods for chemical grouting consolidation of loose gravel areas include: Pass one end of the multiple rows of grouting pipes through the steel arch frame and insert them into the loose gravel area; Reinforcement chemical materials are injected into the loose gravel area from the other end of the grouting pipe until a stable load-bearing structure is formed.

7. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 1, characterized in that: Grouting reinforcement of the initial support structure includes: Single-liquid slurry and double-liquid slurry are used to grout the surrounding rock on the back of the steel arch frame; wherein the single-liquid slurry is cement slurry, and the double-liquid slurry is a mixed slurry of cement and water glass.

8. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 1, characterized in that: The method further comprises: The settlement rate of the steel arch frame is observed using a total station, and the effect of the surrounding rock grouting reinforcement is checked and confirmed using ground penetrating radar or core drilling.

9. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 1, characterized in that: The method further comprises: After the TBM excavates through the poor geological section, temporary steel supports are added to the core section of the collapsed cavity to strengthen the initial support structure. The lower end of the temporary steel support is fixed to the tunnel ground through a pad, and the upper end of the temporary steel support is fixed to the steel arch frame.

10. The construction method of a double-shield open-type TBM in a poor geological section during cavity collapse according to claim 9, characterized in that: After the TBM tunneling is completed, reinforced concrete lining is added on the basis of the initial support structure and the temporary steel support is removed.

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