A method for PBA hole excavation guide hole partition synchronous excavation construction

Abstract

The present application relates to the technical field of underground construction, and discloses a PBA hole excavation pilot hole partition synchronous excavation construction operation method, which comprises the following steps: obtaining bridge foundation information of an existing bridge and pilot hole arrangement information of a to-be-excavated PBA pilot hole group, dividing a bridge area influence window according to the planar projection relationship between the two, dividing pilot hole groups according to the overlapping range of each PBA pilot hole and the bridge area influence window, and configuring excavation control parameters, dividing a load shedding block set according to the bridge area influence window boundary and the adjacent PBA pilot hole contour, and establishing an attribution relationship, determining the adjacent relationship of the load shedding block according to the spatial boundary of the load shedding block, and generating a non-continuous load shedding path, obtaining the support closed state, the bridge deformation monitoring value and the pilot hole deformation monitoring value after the completion of the excavation unit, generating a construction permission state, releasing the next excavation unit construction permission in the release state, and generating a construction parameter adjustment instruction in the lock state. The PBA multi-pilot hole synchronous excavation is subjected to multiple common constraints, and the safety control of the bridge area PBA pilot hole synchronous excavation is improved.

Description

Technical Field

[0001] This invention relates to the field of underground construction technology, specifically to a method for synchronous excavation of pilot tunnels in PBA tunnels. Background Technology

[0002] The PBA (Pit-Based Batteries) method is a common construction method used in urban underground engineering projects involving tunnel excavation. It typically involves pre-excavating several pilot tunnels, within which the support piles, capping beams, top longitudinal beams, central columns, and arch structures are constructed, gradually forming the main structural load-bearing system. This method can decompose large-section underground structures into several smaller-section pilot tunnels, which helps reduce the area excavated at one time and is suitable for underground space construction in areas with existing roads, pipelines, and dense buildings.

[0003] During PBA pilot tunnel construction, to balance construction efficiency and ground stability, measures such as sequential advancement of multiple pilot tunnels, staggered face spacing control, short excavation advances, timely support, and construction monitoring are typically adopted. For construction scenarios involving tunnels passing under existing bridges, piers, abutments, and pile foundations are highly sensitive to disturbances in the surrounding soil. Ground unloading caused by pilot tunnel excavation, delayed support closure, and the superposition of soil disturbances between adjacent pilot tunnels can all impact the bridge foundation and pilot tunnel support structure. Current PBA pilot tunnel construction control focuses primarily on the excavation sequence of individual pilot tunnels, face spacing, and monitoring alarms. The pace of pilot tunnel advancement is also adjusted based on field experience during construction organization. This type of method can meet the control requirements of general tunneling construction. However, when multiple pilot tunnels are advanced simultaneously within the same bridge foundation influence area, relying solely on the excavation status of a single pilot tunnel or a single monitoring indicator is insufficient to accurately reflect the continuous unloading effect of the soil to be excavated between adjacent pilot tunnels. It is also difficult to establish a stable correlation between the support closure status and subsequent construction release. Because the excavation objects between different pilot tunnels lack a unified spatial attribution and construction permit judgment basis, it is easy for the adjacent soil to continue to be released before the support of a local pilot tunnel has formed a closed stress state, thereby increasing the difficulty of controlling differential settlement of bridge foundation and deformation of pilot tunnel support.

[0004] To address the aforementioned issues, it is imperative to innovate the design based on the existing PBA tunnel excavation and pilot tunnel phased synchronous excavation construction. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synchronous excavation of pilot tunnels in sections during PBA tunnel excavation, in order to solve the problems mentioned in the background art regarding the increased difficulty in controlling differential settlement of bridge foundations and deformation of pilot tunnel support in existing PBA tunnel excavation construction.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for synchronous excavation of pilot tunnel sections in a PBA tunnel, comprising the following steps: S1. Obtain the bridge foundation information of the existing bridge and the layout information of the pilot tunnel group to be excavated in PBA. Divide the bridge area influence window according to the planar projection relationship between the bridge foundation information and the pilot tunnel layout information. S2. Based on the overlap range between each PBA pilot tunnel in the PBA pilot tunnel group to be excavated and the bridge area influence window, each PBA pilot tunnel is divided into a sensitive pilot tunnel group, a transition pilot tunnel group, and a normal pilot tunnel group, and excavation control parameters are configured for the sensitive pilot tunnel group, the transition pilot tunnel group, and the normal pilot tunnel group. S3. Based on the boundary of the bridge area influence window and the outline of the adjacent PBA guide tunnels in the PBA guide tunnel group to be excavated, divide the soil to be excavated between adjacent PBA guide tunnels into unloading block sets, and establish the ownership relationship between each unloading block and the bridge area influence window. S4. Determine the adjacent relationship of each unloading block according to the spatial boundary of each unloading block, and generate a discontinuous unloading path according to the attribution relationship, the adjacent relationship of the unloading blocks and the excavation control parameters; S5. After completing an excavation unit determined by the unloading block and the excavation unit length in the excavation control parameters according to the discontinuous unloading path, obtain the support closure status of the excavation unit, the bridge deformation monitoring value and the guide tunnel deformation monitoring value. S6. Generate a construction permit status based on the support closure status, bridge deformation monitoring value, and guide tunnel deformation monitoring value; when the construction permit status is in the release status, release the construction permit for the next excavation unit; when the construction permit status is in the locked status, generate a construction parameter adjustment command.

[0007] Furthermore, this scheme obtains the bridge foundation information of existing bridges and the layout information of the pilot tunnels of the PBA pilot tunnel group to be excavated, and divides the bridge area influence window according to the planar projection relationship between the bridge foundation information and the pilot tunnel layout information, including: The location of the piers, the boundary of the abutment, and the outline of the pile foundation of the existing bridge are obtained to form the bridge foundation information; Obtain the tunnel number, tunnel outline, and longitudinal axis of each PBA tunnel in the PBA tunnel group to be excavated, and form the tunnel layout information; The bridge foundation information is projected onto the PBA pilot tunnel construction plane to obtain the bridge foundation projection area; Based on the net distance relationship between the bridge foundation projection area and the guide tunnel outline of each PBA guide tunnel, the bridge area influence window is divided along the longitudinal and transverse directions of the PBA guide tunnel. Configure the influence window number and influence window level for the bridge area influence window.

[0008] Furthermore, the impact window levels in this plan include sensitive impact window level, transitional impact window level, and ordinary impact window level; Based on the overlap between each PBA pilot tunnel in the PBA pilot tunnel group to be excavated and the bridge area influence window, each PBA pilot tunnel is divided into a sensitive pilot tunnel group, a transitional pilot tunnel group, and a normal pilot tunnel group, including: The influence window level of each PBA tunnel is determined based on the overlap range between the tunnel profile of each PBA tunnel and the influence window of the bridge area. PBA tunnels with an influence window level of sensitive influence window are classified as the sensitive tunnel group; PBA tunnels with an influence window level of transitional influence window level are classified as the transitional tunnel group; PBA tunnels with an influence window level of ordinary influence window are classified into the ordinary tunnel group.

[0009] Furthermore, the excavation control parameters of this scheme include face offset, single-cycle advance, excavation unit length, and upper limit of the number of active faces; the excavation control parameters configured for the sensitive pilot tunnel group, transition pilot tunnel group, and ordinary pilot tunnel group include: Configure the sensitive pilot tunnel group with the first face offset, the first single-cycle advance, the first excavation unit length, and the upper limit of the number of first active faces; Configure the transition tunnel group with a second face offset, a second single-cycle advance, a second excavation unit length, and a maximum number of second active faces; Configure the ordinary pilot tunnel group with the third face offset, the third single-cycle advance, the third excavation unit length, and the upper limit of the number of third active faces; Wherein, the first face offset is greater than the second face offset, the second face offset is greater than the third face offset, the first single-cycle advance is less than the second single-cycle advance, and the second single-cycle advance is less than the third single-cycle advance.

[0010] Furthermore, the upper limit of the number of active working faces in this scheme is used to limit the number of PBA pilot tunnel working faces that are in the excavation state and have not reached the stable state of support closure within the same bridge area influence window; the upper limit of the first active working face is one, and the upper limit of the second active working face is less than the upper limit of the third active working face.

[0011] Furthermore, based on the boundaries of the bridge area influence window and the outlines of adjacent PBA pilot tunnels in the PBA pilot tunnel group to be excavated, this scheme divides the soil to be excavated between adjacent PBA pilot tunnels into unloading block sets, and establishes the attribution relationship between each unloading block and the bridge area influence window, including: Obtain the boundary of the bridge area influence window, the outline of the adjacent PBA guide tunnel, the main structure compartment line, the location of temporary support arrangement and the location of the arch support node; Based on the boundary of the bridge area influence window, the outline of the adjacent PBA guide tunnel, the main structure compartment line, the location of temporary support and the location of the arch support node, the soil to be excavated between adjacent PBA guide tunnels is divided to obtain the unloading block set. Configure each unloading block in the unloading block set with an unloading block number, an influence window number, an adjacent PBA tunnel number, a support node number, and a monitoring point number; Based on the influence window number, establish the affiliation relationship between each unloading block and the influence window of the bridge area.

[0012] Furthermore, this scheme determines the adjacency relationship of each unloading block based on its spatial boundary, and generates a discontinuous unloading path based on the attribution relationship, the adjacency relationship of the unloading blocks, and the excavation control parameters, including: Extract the set of unloading blocks within the same bridge area's influence window based on the aforementioned attribution relationship; Based on the spatial boundaries of each unloading block within the same bridge area's influence window, generate an adjacent relationship table for the unloading blocks; When the opened unloading block has not reached the stable state of support closure, the unloading block adjacent to the opened unloading block is found according to the unloading block adjacent relationship table, and a locking mark is configured on the found unloading block. If the number of active working faces within the same bridge area influence window is less than the upper limit of the number of active working faces, and the unloading block is not configured with a locking mark, the unloading block is identified as a candidate unloading block. Based on the distance between the candidate unloading blocks and the bridge foundation projection area, the candidate unloading blocks are sorted, and the discontinuous unloading path is generated according to the sorting result.

[0013] Furthermore, after completing an excavation unit determined by the unloading block and the excavation unit length in the excavation control parameters according to the discontinuous unloading path, this scheme obtains the support closure status of the excavation unit, bridge deformation monitoring values, and pilot tunnel deformation monitoring values, including: The initial support closed loop state, the construction state of the locking toe component, the construction state of the temporary invert arch, the construction state of the transverse connecting component, the backfilling and grouting state behind the support, and the continuous closed length of the excavation unit are obtained to generate the support closed state. The vertical displacement of the piers, differential settlement of the piers, tilt of the piers, and displacement of the abutments of the existing bridge are obtained to generate the deformation monitoring values ​​of the bridge. The deformation monitoring values ​​of the pilot tunnel are generated by acquiring the tunnel arch subsidence, clearance convergence, initial support stress, central column displacement, and ground settlement of the PBA pilot tunnel adjacent to the excavation unit.

[0014] Furthermore, this scheme generates a construction permit status based on the support closure status, bridge deformation monitoring values, and pilot tunnel deformation monitoring values, including: When the initial support closed ring state, the locking member construction state, the temporary invert arch construction state, the transverse connection member construction state, and the backfill grouting state behind the support are all completed, and the continuous closure length reaches the preset closure length, a support qualification mark is generated, and the support qualification mark corresponds to the support closure stable state. When the bridge deformation monitoring value meets the bridge release threshold, a bridge qualification mark is generated; When the deformation monitoring value of the pilot tunnel meets the pilot tunnel release threshold, a pilot tunnel qualification mark is generated; When the support qualification mark, bridge qualification mark, and pilot tunnel qualification mark are generated simultaneously, a release status is generated; If the support qualification mark, bridge qualification mark, and tunnel qualification mark are not generated simultaneously, a locked state is generated.

[0015] Furthermore, when the construction permit status of this plan is in the "released" state, the construction permit for the next excavation unit will be released. When the construction permit status is locked, determine the influence window number of the bridge area influence window corresponding to the locked status, and lock the construction permit for the next excavation unit under the influence window number. Based on the support closure status under the locked state, the bridge deformation monitoring value, and the pilot tunnel deformation monitoring value, construction parameter adjustment instructions are generated. The construction parameter adjustment instructions include instructions to shorten the single-cycle advance, instructions to increase the face offset, instructions to reduce the upper limit of the number of active faces, instructions to adjust the discontinuous unloading path, instructions to compensate for grouting, and instructions to add temporary supports.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This method for synchronous excavation of PBA tunnels and pilot tunnels in zones associates the bridge foundation information of existing bridges with the layout information of the pilot tunnels of the PBA pilot tunnel group to be excavated, divides the bridge area influence window, and completes the grouping of pilot tunnels, configuration of excavation control parameters, division of unloading block sets, generation of discontinuous unloading paths, and judgment of construction permit status within the bridge area influence window. This transforms the synchronous excavation process of multiple PBA pilot tunnels from a control method that relies solely on construction sequence and monitoring alarms to a construction control method that is jointly constrained by spatial zoning, unloading relationship, support closure status, and deformation monitoring data, as detailed below: 1. By dividing the bridge area influence window using bridge foundation information and PBA pilot tunnel layout information, the pilot tunnel excavation control can correspond to the influence range of bridge piers, abutments, and pile foundations; by dividing the PBA pilot tunnels into sensitive pilot tunnel groups, transition pilot tunnel groups, and ordinary pilot tunnel groups, and configuring the face offset, single-cycle advance, and upper limit of the number of active faces respectively, different excavation intensities are adopted for areas with different influence levels; by dividing the soil to be excavated between adjacent PBA pilot tunnels into unloading block sets and generating discontinuous unloading paths, adjacent unloading blocks within the same bridge area influence window are opened discontinuously, reducing the risk of continuous strip unloading; 2. The construction permit status is generated by combining the support closure status, bridge deformation monitoring values, and pilot tunnel deformation monitoring values, so that there is a clear basis for judging whether the next excavation unit should be released. When the construction permit status is locked, instructions such as shortening the single-cycle advance, increasing the face offset, reducing the upper limit of the number of active faces, adjusting the discontinuous unloading path, compensating for grouting, and adding temporary supports are generated, so that the construction adjustment corresponds to the monitoring results and the support status, which facilitates timely adjustment of construction parameters under abnormal conditions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process for the synchronous excavation of the PBA tunnel guide tunnel in the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: As Figure 1 The present invention provides a technical solution: a method for synchronous excavation of pilot tunnels in PBA tunnels, comprising the following steps: S1. Obtain the bridge foundation information of the existing bridge and the layout information of the pilot tunnels of the PBA pilot tunnel group to be excavated. Divide the bridge area influence window according to the planar projection relationship between the bridge foundation information and the pilot tunnel layout information. The PBA pilot tunnel group to be excavated consists of adjacent PBA pilot tunnels.

[0020] In this embodiment, the bridge foundation information is determined by existing bridge inspection data, on-site measurement results and design drawings. The bridge foundation information includes the pier location, the abutment boundary and the pile foundation outline. The pier location is used to characterize the coordinate position of the pier centerline in the construction plane, the abutment boundary is used to characterize the projection range of the abutment outer contour in the construction plane, and the pile foundation outline is used to characterize the projection range of the pile foundation outer edge in the construction plane.

[0021] The layout information of the pilot tunnels is jointly determined by the PBA (Plain Bridge Engineering) cut-and-cover structure construction drawings, the pilot tunnel excavation plan, and the on-site layout results. This information includes the pilot tunnel number, outline, and longitudinal axis of each PBA pilot tunnel in the PBA pilot tunnel group to be excavated. The pilot tunnel number distinguishes different PBA pilot tunnels, the outline represents the excavation boundary of each PBA pilot tunnel in the construction plane, and the longitudinal axis represents the extension baseline of each PBA pilot tunnel along the route. The bridge foundation projection area is formed by projecting the pier locations, abutment boundaries, and pile foundation outlines onto the PBA pilot tunnel construction plane. This projection area represents the occupied area and adjacent influence range of the existing bridge foundation within the PBA pilot tunnel construction plane.

[0022] After the bridge foundation projection area is formed, the outlines of each PBA guide tunnel are superimposed onto the same PBA guide tunnel construction plane, and the shortest plane distance from the boundary of the bridge foundation projection area to the boundary of each PBA guide tunnel outline is calculated. The shortest plane distance is used to characterize the proximity between the PBA guide tunnel and the bridge foundation projection area.

[0023] Based on the bridge safety assessment report, geological survey data, and the PBA pilot tunnel construction plan, the first control clearance L1 and the second control clearance L2 are determined before excavation, where 0 < L1 < L2. Taking the boundary of the bridge foundation projection area as the benchmark, the first control boundary is formed along the longitudinal and transverse directions of the PBA pilot tunnel according to the first control clearance L1, and the second control boundary is formed according to the second control clearance L2.

[0024] The construction area overlapping with the PBA pilot tunnel within the first control boundary is designated as the sensitive bridge area influence window; the construction area overlapping with the PBA pilot tunnel between the first and second control boundaries is designated as the transition bridge area influence window; and the construction area of ​​the PBA pilot tunnel outside the second control boundary and within the construction monitoring range is designated as the ordinary bridge area influence window. Influence window numbers are assigned to the sensitive bridge area influence windows, transition bridge area influence windows, and ordinary bridge area influence windows, and their influence window levels are sequentially determined as sensitive influence window level, transition influence window level, and ordinary influence window level. The construction monitoring range is determined by the construction monitoring plan before excavation based on the bridge safety assessment report, geological survey data, and the layout range of the PBA pilot tunnel.

[0025] Through the above-described implementation method, S1 outputs a data set including the influence window number, influence window boundary, influence window level, bridge foundation projection area, pilot tunnel number, pilot tunnel outline, and pilot tunnel longitudinal axis, providing a spatial data basis for subsequent division of sensitive pilot tunnel groups, transitional pilot tunnel groups, and ordinary pilot tunnel groups based on the overlap range between each PBA pilot tunnel and the bridge area influence window.

[0026] S2. Based on the overlap range between each PBA pilot tunnel in the PBA pilot tunnel group to be excavated and the influence window of the bridge area, each PBA pilot tunnel is divided into a sensitive pilot tunnel group, a transitional pilot tunnel group, and a normal pilot tunnel group, and excavation control parameters are configured for the sensitive pilot tunnel group, the transitional pilot tunnel group, and the normal pilot tunnel group.

[0027] In this embodiment, the influence window number, influence window boundary, influence window level, pilot tunnel number, pilot tunnel outline, and pilot tunnel longitudinal axis output by S1 are used to superimpose the pilot tunnel outlines of each PBA pilot tunnel in the PBA pilot tunnel group to be excavated with the boundaries of each bridge area influence window onto the same PBA pilot tunnel construction plane. The overlapping range is defined by the plane range in which the pilot tunnel outline enters the bridge area influence window. The overlapping range is used to represent the construction section range of a single PBA pilot tunnel within the bridge area influence window that is affected by the existing bridge foundation. The overlapping range is determined by the closed plane area formed by the intersection of the pilot tunnel outline and the bridge area influence window boundary. The longitudinal start point, longitudinal end point, and the influence window number to which the overlapping range belongs are used as the grouping basis for the PBA pilot tunnel.

[0028] When the overlapping area of ​​a PBA pilot tunnel is within the bridge area influence window corresponding to the sensitive influence window level, the PBA pilot tunnel is classified into a sensitive pilot tunnel group; when the overlapping area of ​​a PBA pilot tunnel is within the bridge area influence window corresponding to the transitional influence window level, the PBA pilot tunnel is classified into a transitional pilot tunnel group; when the overlapping area of ​​a PBA pilot tunnel is within the bridge area influence window corresponding to the ordinary influence window level, the PBA pilot tunnel is classified into an ordinary pilot tunnel group. When the same PBA pilot tunnel crosses two or more influence window levels along its longitudinal axis, the pilot tunnel group to which the PBA pilot tunnel belongs is determined by the highest influence window level it crosses, and the excavation control parameters corresponding to that pilot tunnel group are uniformly adopted in all overlapping construction sections of the PBA pilot tunnel with each bridge area influence window.

[0029] Excavation control parameters include face offset, single-cycle advance, excavation unit length, and upper limit of active faces. Face offset is used to limit the minimum interval between faces along the longitudinal axis of the pilot tunnel within the same bridge area influence window. Single-cycle advance is used to limit the length of one excavation advance. Excavation unit length is used to determine the length of the construction section that needs to be judged for support closure after one excavation. Upper limit of active faces is used to limit the number of PBA pilot tunnel faces within the same bridge area influence window that are in the excavation state and have not reached the stable state of support closure.

[0030] For sensitive pilot tunnel groups, configure the first face offset, the first single-cycle advance, the first excavation unit length, and the upper limit of the number of the first active faces. For transition pilot tunnel groups, configure the second face offset, the second single-cycle advance, the second excavation unit length, and the upper limit of the number of the second active faces. For ordinary pilot tunnel groups, configure the third face offset, the third single-cycle advance, the third excavation unit length, and the upper limit of the number of the third active faces.

[0031] The first face offset is greater than the second face offset, the second face offset is greater than the third face offset, the first single-cycle advance is less than the second single-cycle advance, and the second single-cycle advance is less than the third single-cycle advance. This configuration ensures that construction areas with stronger bridge foundation influence have larger face intervals and shorter single excavation advance lengths. The maximum number of first active faces is set to one, ensuring that within the bridge area influence window corresponding to the same sensitive influence window level, only one PBA pilot tunnel face that has not reached the stable state of support closure is retained in the sensitive pilot tunnel group. The maximum number of second active faces is less than the maximum number of third active faces, making the synchronous excavation intensity of the transition pilot tunnel group lower than that of the ordinary pilot tunnel group.

[0032] After forming the pilot tunnel group and excavation control parameters, the pilot tunnel number, its corresponding pilot tunnel group, its corresponding influence window number, face offset, single-cycle advance, excavation unit length, and upper limit of the number of active faces are written into the pilot tunnel grouping control table. The pilot tunnel grouping control table provides a parameter basis for subsequent unloading block division, discontinuous unloading path generation, and construction permit status judgment. In this embodiment, the advancement of the PBA pilot tunnel face and the excavation of unloading blocks of the soil to be excavated between adjacent PBA pilot tunnels are coordinated and controlled as interrelated excavation operations within the same bridge area influence window. Among them, the face offset and the upper limit of the number of active faces are used to constrain the advancement of the PBA pilot tunnel face, and the single-cycle advance and excavation unit length are used to constrain the longitudinal excavation length of the unloading block. Each unloading block is associated with the adjacent PBA pilot tunnels on both sides by a number. Only when the corresponding construction section of the PBA pilot tunnels on both sides of the unloading block has formed the pilot tunnel outline, and the faces of the PBA pilot tunnels on both sides meet the applicable face offset, will the unloading block enter the candidate unloading block judgment.

[0033] S3. Based on the boundary of the bridge area influence window and the outline of the adjacent PBA guide tunnels in the PBA guide tunnel group to be excavated, divide the soil to be excavated between adjacent PBA guide tunnels into unloading block sets, and establish the affiliation relationship between each unloading block and the bridge area influence window.

[0034] In this embodiment, the bridge area influence window formed by S1 and the pilot tunnel grouping control table formed by S2 are used to extract the boundary of the bridge area influence window, the pilot tunnel outline of adjacent PBA pilot tunnels, the main structure compartment line, the temporary support layout position and the arch support node position. The above objects are then uniformly superimposed on the PBA pilot tunnel construction plane to form a plan control map for dividing the soil to be excavated.

[0035] The main structure partition line refers to the boundary line used to divide the construction sections in the horizontal and vertical construction organization of the PBA main structure. It is used to limit the construction connection range between the soil excavation between the pilot tunnel and the subsequent pile-beam-arch structure, the arch structure and the main excavation structure. The location of temporary support arrangement refers to the installation position of temporary invert arch, temporary cross brace, locking toe component and support conversion component in the construction plane of PBA pilot tunnel. It is used to define the construction boundary that can form local support constraint in time after the soil to be excavated is divided. The location of the arch support node refers to the position where the subsequent arch structure connects with the initial support, cap beam, top longitudinal beam and support connection parts in the pilot tunnel. It is used to limit the control position that needs to be judged for support closure and checked for node connection after the unloading block excavation is completed.

[0036] When dividing the unloading block set, the outline of the adjacent PBA pilot tunnels is used as the two side boundaries of the soil to be excavated, the boundary of the bridge area influence window is used as the control boundary of the bridge foundation influence range, and the main structure compartment line, the location of temporary supports, and the location of the arch support node are used as the dividing boundaries of the soil to be excavated. This divides the soil between adjacent PBA pilot tunnels into unloading blocks with independent excavation sequences and independent support check objects. An unloading block refers to a soil unit between adjacent PBA pilot tunnels designated as a single controlled excavation object. Its technical meaning lies in converting the soil between continuous pilot tunnels into a numberable, attributable, lockable, and releaseable construction control unit, thereby providing an object basis for the subsequent generation of discontinuous unloading paths. The boundary of each unloading block is jointly defined by the outline of the adjacent PBA pilot tunnels, the boundary of the bridge area influence window, the main structure compartment line, the location of temporary supports, and the location of the arch support node, ensuring that each unloading block has a defined excavation range on the plane and a defined support closure check position in the construction organization.

[0037] After obtaining the unloading block set, each unloading block in the set is assigned an unloading block number, its associated influence window number, adjacent PBA pilot tunnel number, support node number, and monitoring point number. The unloading block number is used to distinguish different unloading blocks, the associated influence window number indicates the bridge area influence window to which the unloading block belongs, the adjacent PBA pilot tunnel number indicates which two adjacent PBA pilot tunnels the unloading block is located between, the support node number indicates the support connection position that needs to be checked after the unloading block is excavated, and the monitoring point number indicates the bridge deformation monitoring value and pilot tunnel deformation monitoring value that need to be associated and read during the excavation of the unloading block.

[0038] The influence window number is determined based on the positional relationship between the unloading block's planar range and the bridge area influence window boundary. When the unloading block's planar range is entirely within a bridge area influence window, the influence window number of that bridge area influence window is written into the unloading block's influence window number. When the unloading block's planar range crosses bridge area influence windows of different influence window levels, the bridge area influence window with the highest influence window level is determined as the unloading block's assigned bridge area influence window, and its influence window number is written into the unloading block's influence window number. When the unloading block's planar range crosses two or more bridge area influence windows of the same highest influence window level, the bridge area influence window with the largest overlap area with the unloading block is determined as the primary assigned bridge area influence window, and its influence window number is written into the unloading block's influence window number. The primary bridge area influence window refers to the bridge area influence window with the largest overlapping area when the unloading block crosses two or more bridge area influence windows of the same highest influence window level. By determining a unique primary bridge area influence window for the unloading block, an unloading block is controlled by only one bridge area influence window in the subsequent generation of discontinuous unloading paths and the judgment of construction permit status. The support node number is determined based on the location of the temporary support arrangement near the boundary of the unloading block and the location of the arch support node. The support node number is then bound to the unloading block number so that after the unloading block is excavated, the initial support closed ring status, the construction status of the locking toe component, the construction status of the temporary invert arch, the construction status of the transverse connection component, and the backfill grouting status behind the support can be read according to the support node number. The monitoring point number is determined based on the influence window number to which the unloading block belongs, the adjacent PBA pilot tunnel number, and the monitoring layout of the existing bridge. The numbers of the pier vertical displacement monitoring points, pier differential settlement monitoring points, pier tilt monitoring points, abutment displacement monitoring points, pilot tunnel arch settlement monitoring points, clearance convergence monitoring points, initial support stress monitoring points, central column displacement monitoring points, and surface settlement monitoring points are written into the monitoring point number field of the unloading block.

[0039] By configuring the unloading block number, the corresponding influence window number, the adjacent PBA tunnel number, the support node number, and the monitoring point number, an unloading block control record is formed. The unloading block control record is used to indicate the spatial location of each unloading block, its bridge area affiliation, adjacent PBA tunnels, support verification objects, and monitoring data sources. When establishing the affiliation relationship, the unloading block control record is written into the unloading block list of the bridge area influence window using the corresponding influence window number as an index, so that each bridge area influence window has a set of unloading blocks under its control.

[0040] Through the above processing, S3 outputs data results including the unloading block set, unloading block control records, and the attribution relationship between each unloading block and the bridge area influence window, providing construction control objects for subsequent determination of the adjacent relationship of unloading blocks based on the spatial boundary of unloading blocks and generation of discontinuous unloading paths.

[0041] S4. Determine the adjacent relationships of unloading blocks based on the spatial boundaries of each unloading block, and generate discontinuous unloading paths based on the attribution relationship, the adjacent relationships of unloading blocks, and the excavation control parameters.

[0042] In this embodiment, the unloading block set, unloading block control record, and the relationship between each unloading block and the bridge area influence window output by S3 are used to extract the unloading block set within the same bridge area influence window using the influence window number as the index, and the spatial boundaries of each unloading block in the unloading block set are superimposed onto the same PBA pilot tunnel construction plane.

[0043] The adjacent relationship of unloading blocks refers to any spatial relationship between two unloading blocks within the same bridge area's influence window, including shared boundaries, shared support node boundaries, or a planar interval smaller than the preset construction interval. The preset construction interval is determined by the construction plan based on the influence window level and the pilot tunnel spacing. Its technical meaning is to identify unloading block combinations that may form continuous unloading influence after excavation. Based on the spatial boundaries of each unloading block within the same bridge area's influence window, boundary adjacency identification is performed on each unloading block. When two unloading blocks share a common boundary, a shared support node boundary, or a planar interval smaller than the preset construction interval, these two unloading blocks are recorded as adjacent unloading blocks, and an unloading block adjacent relationship table is generated.

[0044] The unloading block adjacency table includes the current unloading block number, adjacent unloading block numbers, the corresponding influence window number, the adjacent boundary type, and the adjacent boundary length. The current unloading block number identifies the unloading block being judged; the adjacent unloading block number identifies the unloading block that forms an adjacency with the current unloading block; the corresponding influence window number identifies the bridge area influence window to which this adjacency belongs; the adjacent boundary type characterizes the relationship type of shared boundary, shared support node boundary, and planar interval proximity; and the adjacent boundary length characterizes the boundary length of spatial proximity between two unloading blocks. After generating the unloading block adjacency table, the support closure status of the opened unloading blocks is read. If the opened unloading block has not reached a stable support closure state, the adjacent unloading block is searched according to the unloading block adjacency table, and a locking flag is configured for the found unloading block. The locking flag indicates that the unloading block must not be opened in the current construction cycle. Its technical meaning is to block the continuous excavation of adjacent unloading blocks, preventing the formation of continuous strip-shaped unloading zones in the soil between guide tunnels within the same bridge area influence window.

[0045] Before determining the candidate unloading blocks, the upper limit of the number of active working faces applicable to the unloading blocks is first determined. The upper limit of the number of active working faces applicable to the unloading blocks is used to limit the number of PBA pilot tunnel working faces that are in the excavation state and have not reached the support closure and stability state within the influence window of the bridge area to which the unloading block belongs. When the unloading block is located between adjacent PBA pilot tunnels in the same pilot tunnel group, the upper limit of the number of active working faces in that pilot tunnel group is determined as the upper limit of the number of active working faces applicable to the unloading block. When the unloading block is located between adjacent PBA pilot tunnels in different pilot tunnel groups, the upper limit of the number of active working faces in the pilot tunnel group with the higher influence window level among the two PBA pilot tunnels is determined as the upper limit of the number of active working faces applicable to the unloading block. The influence window levels are from high to low as sensitive influence window level, transitional influence window level and ordinary influence window level.

[0046] When determining candidate unloading blocks, the number of PBA pilot tunnel faces that are in the excavation state and have not reached the stable state of support closure within the same bridge area's influence window is counted to obtain the current number of active faces. If the current number of active faces is less than the upper limit of the number of active faces applicable to unloading blocks, and the unloading block is not equipped with a locking mark, the unloading block is determined as a candidate unloading block. A candidate unloading block refers to an unloading block that is qualified to participate in the sorting and opening judgment in the current construction cycle. To determine the opening order of candidate unloading blocks, the distance value between the candidate unloading block and the bridge foundation projection area is calculated. The distance value is the shortest planar distance between the center point of the candidate unloading block and the boundary of the bridge foundation projection area.

[0047] In one implementation, the shortest planar distance from the center point of each candidate unloading block to the boundary of the bridge foundation projection area is calculated, and the candidate unloading blocks are sorted from largest to smallest according to the shortest planar distance; when the shortest planar distance of two or more candidate unloading blocks is the same, the order is determined according to the unloading block number from smallest to largest, so as to form a unique candidate unloading block sorting result.

[0048] The next unloading block to be opened is determined sequentially according to the candidate unloading block sorting results, forming a discontinuous unloading path. The discontinuous unloading path refers to the excavation sequence of unloading blocks that makes adjacent unloading blocks open discontinuously within the same bridge area influence window. Its technical meaning is to control the soil unloading process between the pilot tunnels through spatial intervals and support closure constraints.

[0049] Through the above processing, S4 outputs the adjacent relationship table of unloading blocks, locking flag, candidate unloading block sorting results and discontinuous unloading paths, providing the basis for excavation objects and construction sequence for obtaining the support closure status, bridge deformation monitoring values ​​and pilot tunnel deformation monitoring values ​​after completing an excavation unit.

[0050] S5. After completing an excavation unit determined by the length of the excavation unit in the excavation control parameters according to the discontinuous unloading path, obtain the support closure status of the excavation unit, the bridge deformation monitoring value, and the guide tunnel deformation monitoring value.

[0051] In this embodiment, the construction control system receives the discontinuous unloading path and the determined excavation unit output by S4. After the excavation unit completes the soil excavation, initial support construction and temporary support installation, it reads the site acceptance record, construction record and monitoring data, and uses the reading results as the data source for the subsequent construction permit status generation.

[0052] An excavation unit refers to a single construction check section within the spatial boundary of an unloading block to be opened, along the longitudinal direction of the PBA guide tunnel, according to the applicable excavation unit length of the unloading block. The same excavation unit shall not cross the boundary of the unloading block. When the remaining longitudinal length of the unloading block is less than the length of the excavation unit, the remaining longitudinal length shall be used as the actual length of the last excavation unit. By dividing the unloading block into excavation units that can independently collect support status and monitoring status, subsequent construction permits shall be judged based on the currently completed excavation units. The support closure state is jointly formed by the initial support closure ring state, the construction state of the anchor bolt components, the construction state of the temporary invert arch, the construction state of the transverse connection components, the backfilling and grouting state behind the support, and the continuous closure length. The initial support closure ring state indicates whether the shotcrete, steel mesh, and grid steel frame have formed a closed stress ring within the excavation unit. The anchor bolt component construction state indicates whether the anchor bolts, anchor bolts, and anchor bolt connectors at the arch foot and sidewall foot have been installed. The temporary invert arch construction state indicates whether the temporary closure components at the bottom of the pilot tunnel have been constructed. The transverse connection component construction state indicates whether the transverse tie and support conversion components between adjacent support sections have been connected. The backfilling and grouting state behind the support indicates whether the gaps behind the initial support have been filled. The continuous closure length indicates the longitudinal length of the closed support.

[0053] When obtaining the initial support closed loop status, read the site acceptance record, support installation record and image verification data to confirm that the grid steel frame installation, shotcrete covering and support circumferential connection are completed within the excavation unit, and write the confirmation result into the initial support closed loop status field. When obtaining the construction status of the anchor component, read the anchor component construction record and on-site measurement record to confirm that the installation position, quantity, anchorage length and connection node of the anchor component meet the support design requirements of the excavation unit, and write the confirmation result into the anchor component construction status field. When obtaining the construction status of the temporary invert arch, read the temporary invert arch construction record, bottom closure measurement record and concrete pouring record, confirm that the temporary invert arch forms a bottom closure with the initial support on both sides in the excavation unit, and write the confirmation result into the temporary invert arch construction status field. When obtaining the construction status of the transverse connection component, read the installation record and node verification record of the transverse connection component to confirm that the transverse connection component has connected the adjacent support section in the excavation unit, and write the confirmation result into the construction status field of the transverse connection component. When obtaining the backfill grouting status behind the support, read the grouting pressure record, grouting volume record and backfilling completion record to confirm that the void behind the initial support in the excavation unit has been backfilled and write the confirmation result into the backfill grouting status field behind the support. When obtaining the continuous closed length, the longitudinal starting point of the excavation unit is taken as the measurement starting point, and the longitudinal endpoint of the initial support closed loop, the completion of the locking toe component, the completion of the temporary invert arch, the completion of the transverse connection component, and the completion of the backfill grouting behind the support is taken as the measurement endpoint. The longitudinal distance between the two is calculated and written into the continuous closed length field.

[0054] The bridge deformation monitoring values ​​are formed by the vertical displacement of the piers, differential settlement of the piers, tilting of the piers, and displacement of the abutment of the existing bridge. The vertical displacement of the piers is used to represent the settlement change of the pier measuring point relative to the benchmark elevation before construction. The differential settlement of the piers is used to represent the settlement difference between the measuring points of adjacent piers of the same bridge foundation. The tilting of the piers is used to represent the deflection of the pier axis relative to the initial axis. The displacement of the abutment is used to represent the planar displacement of the abutment measuring point relative to the benchmark position before construction. When acquiring bridge deformation monitoring values, the monitoring data of the pier vertical displacement monitoring points, pier differential settlement monitoring points, pier tilt monitoring points, and abutment displacement monitoring points in the bridge area influence window to which the excavation unit belongs are read according to the monitoring point number in the unloading block control record in S3, and written into the bridge deformation monitoring value field according to the acquisition time.

[0055] The deformation monitoring values ​​of the pilot tunnel are jointly formed by the settlement of the pilot tunnel arch, the clearance convergence, the initial support stress, the displacement of the central column, and the ground settlement of the PBA pilot tunnels adjacent to the excavation unit. Among them, the settlement of the pilot tunnel arch is used to represent the settlement change of the pilot tunnel arch measuring point relative to the initial elevation; the clearance convergence is used to represent the change of the horizontal distance between the measuring points on both sides of the pilot tunnel; the initial support stress is used to represent the stress change of the initial support components; the central column displacement is used to represent the horizontal and vertical displacement of the central column measuring point of the PBA structure; and the ground settlement is used to represent the settlement change of the ground measuring point above the pilot tunnel relative to the benchmark elevation before construction. When acquiring the deformation monitoring values ​​of the pilot tunnel, the monitoring data of the pilot tunnel arch subsidence monitoring point, clearance convergence monitoring point, initial support stress monitoring point, central column displacement monitoring point and surface settlement monitoring point corresponding to the adjacent PBA pilot tunnel are read according to the PBA pilot tunnel number adjacent to the excavation unit and the influence window number of the bridge area influence window to which the excavation unit belongs, and written into the pilot tunnel deformation monitoring value field according to the acquisition time.

[0056] To ensure that the support closure status, bridge deformation monitoring values, and pilot tunnel deformation monitoring values ​​can be verified within the same construction cycle, the above data are encapsulated according to the excavation unit number, the influence window number, the adjacent PBA pilot tunnel number, the unloading block number, and the acquisition time to form an excavation unit status record. The excavation unit status record is used to characterize the support completion status, the existing bridge response status, and the PBA pilot tunnel deformation status after the completion of an excavation unit. Its technical significance lies in providing a unified data object for generating the construction permit status based on the support closure status, bridge deformation monitoring values, and pilot tunnel deformation monitoring values.

[0057] Through the above processing, S5 outputs data results including the support closure status, bridge deformation monitoring values, pilot tunnel deformation monitoring values, and excavation unit status records, providing a verification basis for subsequent judgment of the release status and locking status.

[0058] S6. Generate a construction permit status based on the support closure status, bridge deformation monitoring values, and pilot tunnel deformation monitoring values; when the construction permit status is in the release status, release the construction permit for the next excavation unit; when the construction permit status is in the locked status, generate a construction parameter adjustment command.

[0059] In this embodiment, the construction control system receives the excavation unit status record output by S5, reads the support closure status, bridge deformation monitoring value and pilot tunnel deformation monitoring value from the excavation unit status record, and inputs the above three types of data into the support verification process, bridge verification process and pilot tunnel verification process respectively. The support verification process is used to determine whether the completed excavation unit has reached the support closure stability condition. Its technical meaning is to confirm that the excavation unit has formed a closed support structure that can withstand subsequent unloading disturbances; the support closure stability state refers to the state in which the support qualification mark is generated.

[0060] When the initial support is closed into a ring, the anchor bolt construction is complete, the temporary invert arch construction is complete, the transverse connecting component construction is complete, and the backfilling and grouting behind the support is complete, and the continuous closure length reaches the preset closure length, a support qualification mark is generated. The preset closure length is determined before excavation by the PBA pilot tunnel design documents, support structure design requirements, and construction special plan. When any of the following conditions is not met: initial support closed into a ring, anchor bolt construction, temporary invert arch construction, transverse connecting component construction, backfilling and grouting behind the support, or continuous closure length, a support qualification mark is not generated.

[0061] The bridge verification process is used to determine whether the deformation response of an existing bridge after the construction of the current excavation unit meets the requirements for continued excavation. The bridge release threshold is determined before excavation by the bridge safety assessment report, the existing bridge inspection report and the construction monitoring plan, and includes the cumulative control threshold and the rate of change control threshold corresponding to the vertical displacement of the pier, the differential settlement of the pier, the tilt of the pier and the displacement of the abutment, respectively.

[0062] The vertical displacement of the bridge piers, differential settlement of the bridge piers, tilting of the bridge piers, and displacement of the abutment are compared with their respective cumulative control thresholds. The rate of change of each bridge deformation monitoring value in adjacent collection periods is compared with its respective rate of change control threshold. A bridge qualification mark is generated when none of the bridge deformation monitoring values ​​exceed their respective cumulative control thresholds and none of the rates of change of the bridge deformation monitoring values ​​exceed their respective rate of change control thresholds. No bridge qualification mark is generated when any bridge deformation monitoring value or its rate of change exceeds the corresponding threshold.

[0063] The pilot tunnel verification process is used to determine whether the deformation response of the PBA pilot tunnel adjacent to the current excavation unit meets the requirements for continued construction. Its technical meaning is to prevent the unloading blocks from being released before the support deformation of the adjacent PBA pilot tunnel has stabilized.

[0064] The threshold for pilot tunnel release is determined before excavation by the PBA pilot tunnel design documents, construction special plan, and construction monitoring plan. It includes cumulative control thresholds and rate-of-change control thresholds corresponding to pilot tunnel crown settlement, clearance convergence, initial support stress, central column displacement, and surface settlement, respectively. The pilot tunnel crown settlement, clearance convergence, initial support stress, central column displacement, and surface settlement are compared with their respective cumulative control thresholds. The rate of change of each pilot tunnel deformation monitoring value within adjacent acquisition periods is also compared with its corresponding rate-of-change control threshold. A pilot tunnel qualification mark is generated when all pilot tunnel deformation monitoring values ​​do not exceed their respective cumulative control thresholds, and the rate of change of each pilot tunnel deformation monitoring value does not exceed its corresponding rate-of-change control threshold. No pilot tunnel qualification mark is generated when any pilot tunnel deformation monitoring value or its rate of change exceeds the corresponding threshold. When the support qualification mark, bridge qualification mark, and pilot tunnel qualification mark are generated simultaneously, the construction control system will set the construction permit status of the bridge area influence window of the current excavation unit to the open state; when the support qualification mark, bridge qualification mark, and pilot tunnel qualification mark are not generated simultaneously, the construction control system will set the construction permit status of the bridge area influence window of the current excavation unit to the locked state.

[0065] When the construction permit status is in the release state, the construction control system reads the discontinuous unloading path generated by S4 and releases the construction permit for the next excavation unit according to the excavation object sorted after the current excavation unit in the discontinuous unloading path.

[0066] The next excavation unit construction permit refers to the control instruction that allows construction personnel to open the next pilot tunnel face advancement permit and the next unloading block excavation permit within the same bridge area influence window. Its technical meaning is to transform the support closure result, bridge deformation result and pilot tunnel deformation result into subsequent construction access conditions.

[0067] When the construction permit status is locked, the construction control system reads the influence window number in the current excavation unit status record and determines the influence window number corresponding to the locked status. Based on the influence window number, the construction control system locks the construction permit for the next excavation unit within the influence window of the bridge area, so that the advancement of the next pilot tunnel face and the excavation of the next unloading block within the influence window of the bridge area remain in an unreleased state. The construction parameter adjustment command is generated based on the qualified identification type not generated in the locked status. When no qualified support identification is generated, the command to add temporary support, the command to compensate grouting, and the command to adjust the discontinuous unloading path are generated.

[0068] When no bridge qualification mark is generated, commands to shorten the single-cycle advance, increase the tunnel face offset, reduce the upper limit of the number of active tunnel faces, and compensate for grouting are generated; when no pilot tunnel qualification mark is generated, commands to shorten the single-cycle advance, adjust the discontinuous unloading path, add temporary support, and reduce the upper limit of the number of active tunnel faces are generated.

[0069] The "Shorten Single-Cycle Advance" command adjusts the advance length of subsequent excavation units within the current bridge area influence window to a length less than the original single-cycle advance length. The "Increase Face Stagger" command expands the longitudinal distance between adjacent PBA pilot tunnel faces within the same bridge area influence window. The "Decrease Active Face Count Limit" command reduces the number of faces within the same bridge area influence window that have not reached the stable state of support closure. The "Adjust Discontinuous Unloading Path" command re-calls the adjacent relationships of unloading blocks and the sorting results of candidate unloading blocks in S4. The "Compensation Grouting" command grouts and reinforces the soil adjacent to the bridge foundation projection area and the voids behind the initial support. The "Add Temporary Support" command adds temporary cross braces, temporary inverts, and locking components within the current excavation unit and its adjacent support sections.

[0070] After the construction parameter adjustment command is executed, the construction control system re-collects the bridge deformation monitoring values ​​and pilot tunnel deformation monitoring values ​​within the current bridge area's influence window, and re-reads the support closure status of the current excavation unit after executing the construction parameter adjustment command. Through the above processing, S6 outputs the release status, lock status, construction permit for the next excavation unit, and construction parameter adjustment command, transforming the synchronous excavation of the PBA pilot tunnel from an experience-based continuous advancement to a permit-based construction control constrained by the support closure status, bridge deformation status, and pilot tunnel deformation status. When the re-collected support closure status generates a support qualification mark, the bridge deformation monitoring value generates a bridge qualification mark, and the pilot tunnel deformation monitoring value generates a pilot tunnel qualification mark, the lock status under the influence window number is released, and the construction permit for the next excavation unit is released according to the updated discontinuous unloading path; when none of the above three qualification marks are generated simultaneously, the lock status under the influence window number is maintained.

[0071] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., 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 synchronous excavation of pilot tunnels in sections during PBA tunnel excavation, characterized in that, The method includes the following steps: S1. Obtain the bridge foundation information of the existing bridge and the layout information of the pilot tunnel group to be excavated in PBA. Divide the bridge area influence window according to the planar projection relationship between the bridge foundation information and the pilot tunnel layout information. Project the bridge foundation information onto the PBA pilot tunnel construction plane to obtain the bridge foundation projection area. S2. Based on the overlap range between each PBA pilot tunnel in the PBA pilot tunnel group to be excavated and the bridge area influence window, each PBA pilot tunnel is divided into a sensitive pilot tunnel group, a transitional pilot tunnel group, and a normal pilot tunnel group, and excavation control parameters are configured for the sensitive pilot tunnel group, the transitional pilot tunnel group, and the normal pilot tunnel group; the excavation control parameters include the face offset, single-cycle advance, excavation unit length, and the upper limit of the number of active faces; the upper limit of the number of active faces is used to limit the number of PBA pilot tunnel faces that are in the excavation state and have not reached the support closure stability state within the same bridge area influence window. S3. Based on the boundary of the bridge area influence window and the guide tunnel outlines of adjacent PBA guide tunnels in the PBA guide tunnel group to be excavated, the soil to be excavated between adjacent PBA guide tunnels is divided into unloading block sets, and the affiliation relationship between each unloading block and the bridge area influence window is established; wherein, the boundary of the bridge area influence window, the guide tunnel outline of adjacent PBA guide tunnels, the main structure compartment line, the temporary support layout position, and the arch support node position are obtained; based on the boundary of the bridge area influence window, the guide tunnel outline of adjacent PBA guide tunnels, the main structure compartment line, the temporary support layout position, and the arch support node position, the soil to be excavated between adjacent PBA guide tunnels is divided to obtain the unloading block set; each unloading block in the unloading block set is assigned an unloading block number, influence window number, adjacent PBA guide tunnel number, support node number, and monitoring point number; based on the influence window number, the affiliation relationship between each unloading block and the bridge area influence window is established; S4. Determine the adjacency relationship of each unloading block based on its spatial boundary, and generate a discontinuous unloading path based on the attribution relationship, the adjacency relationship of the unloading blocks, and the excavation control parameters. Specifically, extract the set of unloading blocks within the same bridge area influence window based on the attribution relationship; generate an adjacency relationship table for each unloading block within the same bridge area influence window based on its spatial boundary; when an activated unloading block has not reached a stable support closure state, find the unloading block adjacent to the activated unloading block according to the adjacency relationship table, and configure a locking identifier for the found unloading block; when the number of active working faces within the same bridge area influence window is less than the upper limit of the number of active working faces, and the unloading block is not configured with a locking identifier, determine the unloading block as a candidate unloading block; sort the candidate unloading blocks according to the distance between the candidate unloading block and the bridge foundation projection area, and generate the discontinuous unloading path according to the sorting result. S5. After completing an excavation unit determined by the unloading block and the excavation unit length in the excavation control parameters according to the discontinuous unloading path, the support closure state, bridge deformation monitoring value, and guide tunnel deformation monitoring value of the excavation unit are obtained; wherein, the initial support closed loop state, the locking toe component construction state, the temporary invert arch construction state, the transverse connecting component construction state, the backfill grouting state behind the support, and the continuous closure length of the excavation unit are obtained, and the support closure state is generated. S6. Generate a construction permit status based on the support closure status, bridge deformation monitoring value, and guide tunnel deformation monitoring value; when the initial support closure ring status, locking member construction status, temporary invert arch construction status, transverse connection member construction status, and backfilling grouting status behind the support are all completed, and the continuous closure length reaches the preset closure length, generate a support qualification mark, which corresponds to the support closure stability status; when the bridge deformation monitoring value meets the bridge release threshold, generate a bridge qualification mark; when the guide tunnel deformation monitoring value meets the guide tunnel release threshold, generate a guide tunnel qualification mark; when the support qualification mark, bridge qualification mark, and guide tunnel qualification mark are generated simultaneously, a release status is generated; when the construction permit status is a release status, release the construction permit for the next excavation unit; when the support qualification mark, bridge qualification mark, and guide tunnel qualification mark are not generated simultaneously, a locked status is generated; when the construction permit status is a locked status, generate a construction parameter adjustment command.

2. The method for synchronous excavation of pilot tunnel sections in a PBA tunnel according to claim 1, characterized in that: The process of acquiring bridge foundation information of existing bridges and pilot tunnel layout information of the PBA pilot tunnel group to be excavated, and dividing the bridge area influence window according to the planar projection relationship between the bridge foundation information and the pilot tunnel layout information, includes: The location of the piers, the boundary of the abutment, and the outline of the pile foundation of the existing bridge are obtained to form the bridge foundation information; Obtain the tunnel number, tunnel outline, and longitudinal axis of each PBA tunnel in the PBA tunnel group to be excavated, and form the tunnel layout information; Based on the net distance relationship between the bridge foundation projection area and the guide tunnel outline of each PBA guide tunnel, the bridge area influence window is divided along the longitudinal and transverse directions of the PBA guide tunnel. Configure the influence window number and influence window level for the bridge area influence window.

3. The method for synchronous excavation of pilot tunnels in sections according to claim 2, characterized in that: The impact window levels include sensitive impact window level, transitional impact window level and normal impact window level; Based on the overlap between each PBA pilot tunnel in the PBA pilot tunnel group to be excavated and the bridge area influence window, each PBA pilot tunnel is divided into a sensitive pilot tunnel group, a transitional pilot tunnel group, and a normal pilot tunnel group, including: The influence window level of each PBA tunnel is determined based on the overlap range between the tunnel profile of each PBA tunnel and the influence window of the bridge area. PBA tunnels with an influence window level of sensitive influence window are classified as the sensitive tunnel group; PBA tunnels with an influence window level of transitional influence window level are classified as the transitional tunnel group; PBA tunnels with an influence window level of ordinary influence window are classified into the ordinary tunnel group.

4. The method for synchronous excavation of pilot tunnel sections in a PBA tunnel according to claim 3, characterized in that: Configure excavation control parameters for the sensitive pilot tunnel group, the transition pilot tunnel group, and the ordinary pilot tunnel group, including: Configure the sensitive pilot tunnel group with the first face offset, the first single-cycle advance, the first excavation unit length, and the upper limit of the number of first active faces; Configure the transition tunnel group with a second face offset, a second single-cycle advance, a second excavation unit length, and a maximum number of second active faces; Configure the ordinary pilot tunnel group with the third face offset, the third single-cycle advance, the third excavation unit length, and the upper limit of the number of third active faces; Wherein, the first face offset is greater than the second face offset, the second face offset is greater than the third face offset, the first single-cycle advance is less than the second single-cycle advance, and the second single-cycle advance is less than the third single-cycle advance.

5. The method for synchronous excavation of pilot tunnels in sections according to claim 4, characterized in that: The maximum number of the first active working face is one, and the maximum number of the second active working face is less than the maximum number of the third active working face.

6. The method for synchronous excavation of pilot tunnels in sections according to claim 1, characterized in that: After completing an excavation unit determined by the unloading block and the excavation unit length in the excavation control parameters according to the discontinuous unloading path, the support closure status of the excavation unit, bridge deformation monitoring values, and pilot tunnel deformation monitoring values ​​are obtained, including: The vertical displacement of the piers, differential settlement of the piers, tilt of the piers, and displacement of the abutments of the existing bridge are obtained to generate the deformation monitoring values ​​of the bridge. The deformation monitoring values ​​of the pilot tunnel are generated by acquiring the tunnel arch subsidence, clearance convergence, initial support stress, central column displacement, and ground settlement of the PBA pilot tunnel adjacent to the excavation unit.

7. The method for synchronous excavation of pilot tunnels in sections according to claim 1, characterized in that: When the construction permit status is "released", release the construction permit for the next excavation unit. When the construction permit status is locked, determine the influence window number of the bridge area influence window corresponding to the locked status, and lock the construction permit for the next excavation unit under the influence window number. Based on the support closure status under the locked state, the bridge deformation monitoring value, and the pilot tunnel deformation monitoring value, construction parameter adjustment instructions are generated. The construction parameter adjustment instructions include instructions to shorten the single-cycle advance, instructions to increase the face offset, instructions to reduce the upper limit of the number of active faces, instructions to adjust the discontinuous unloading path, instructions to compensate for grouting, and instructions to add temporary supports.

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