Hard rock tunnel deep buried center ditch step-by-step accurate excavation construction method

Abstract

The application relates to the field of hard rock single-track railway tunnel deep-buried center ditch construction excavation, and discloses a hard rock tunnel deep-buried center ditch step-by-step accurate excavation construction method, which establishes a ditch independent operation platform at the rear of a main line excavation operation system, maintains a longitudinal separation distance, cuts two vertical isolation grooves along a design boundary by using a double-cantilever symmetrical cutting mechanism, arranges a center slotting hole and an edge row hole in a center rock body between the isolation grooves, controls a network differential delay initiation by blasting, and synchronously clears and transports rock slag in a main slag discharge time window. The application controls the cutting depth and the blasting delay time in combination with rock mechanics parameters, blocks blasting stress waves by using pre-cut isolation grooves and damping air holes, realizes space-time cooperation of the center ditch and the main line construction, controls over-excavation and under-excavation, and improves construction efficiency and forming quality.

Description

Technical Field

[0001] This invention relates to the field of construction and excavation technology for deep-buried central drainage ditches in hard rock single-track railway tunnels, specifically a step-by-step precise excavation method for deep-buried central drainage ditches in hard rock tunnels. Background Technology

[0002] In the construction of long-distance hard rock tunnels for high-speed railways and highways, deeply buried central drainage ditches are a key structure to ensure the smooth operation of the tunnel's drainage system. Conventional central drainage ditch excavation is usually attached to the construction of the tunnel's main arch, using direct drill-and-blast method to break up the rock mass simultaneously with or slightly after the tunnel face, followed by the removal of excavated soil using the main line's muck removal machinery.

[0003] This traditional construction method presents significant scheduling conflicts in actual engineering projects. Due to the large excavation depth and long operation cycle of the deep-buried central drainage ditch, construction equipment needs to occupy the limited space in the invert arch area for extended periods, which severely restricts the passage of various large machinery and material transportation along the tunnel mainline. Simultaneously, the muck removal operations in the drainage ditch often overlap with the regular muck removal operations at the tunnel face, leading to mutual waiting between different processes and making it difficult to achieve parallel progress across multiple work faces, thus slowing down the overall tunnel's cyclical advance.

[0004] Direct drilling and blasting excavation of the central drainage ditch in hard rock makes it difficult to effectively control the quality of the excavation. The stress waves generated by the blasting spread rapidly through the bedrock, easily causing hidden damage to the outer side of the drainage ditch and the retained rock mass of the invert arch bottom. The intense vibrations not only undermine the overall bearing capacity of the bedrock but also lead to severe over- and under-excavation of the drainage ditch sidewalls, requiring a large amount of concrete for backfilling later, increasing construction costs, and failing to meet the high-precision profile requirements of modern tunnels. Summary of the Invention

[0005] The technical problem solved by this invention is that in the construction of central drainage ditches in existing hard rock tunnels, the direct drill-and-blast method, which is carried out in sequence with the main tunnel invert, is commonly used. This method suffers from spatial interference between excavation and main tunnel construction, as well as long waiting times.

[0006] Meanwhile, the stress waves generated by conventional blasting are easily transmitted to the bottom plate, causing damage to the retained rock mass and over- or under-excavation of the ditch outline, making it difficult to control the construction progress and the quality of the finished product.

[0007] To address the above problems, the present invention provides the following technical solution:

[0008] This invention provides a method for step-by-step precise excavation of a central drainage ditch in a deep-buried hard rock tunnel, comprising the following steps:

[0009] Construction preparation and space pre-planning steps:

[0010] Establish the longitudinal spatial position of the independent working platform for the drainage ditch behind the main excavation system of the tunnel, and maintain a longitudinal separation distance between the independent working platform for the drainage ditch and the working face of the invert arch.

[0011] Contour pre-cutting and end vibration reduction boundary construction steps: On the independent working platform of the ditch, the double cantilever symmetrical cutting mechanism is used to cut along the two sides of the central ditch design into the rock mass to form two vertical isolation grooves;

[0012] Drilling and controlled blasting steps: A central cut-out and a side cut-out are arranged in the central rock mass between two vertical isolation trenches, and a micro-delay detonation is performed through a controlled blasting network;

[0013] Construction waste removal system and implementation steps:

[0014] The rock debris generated from the blasting of the central drainage ditch was removed, and the independent working platform for the drainage ditch was moved forward along with the main excavation system.

[0015] Preferably, in the construction preparation and spatial pre-positioning steps, the process of establishing the longitudinal separation distance includes: obtaining the maximum longitudinal occupancy length of the independent working platform for the ditch and its equipment, as well as the safety buffer distance at the front and rear ends;

[0016] The initial ratio is obtained by dividing the sum of the maximum occupied length, the safety buffer distances at the front and rear ends by the standard advance length of the invert arch in a single cycle.

[0017] The maximum value between the preset constant value and the initial ratio is taken and rounded up to obtain the cycle base; the cycle base is multiplied by the standard advance length of the single cycle of the invert arch to obtain the longitudinal separation distance.

[0018] Preferably, in the contour pre-cutting and end vibration damping boundary construction steps, the process for determining the upper limit of the single-layer cutting depth of the double cantilever symmetrical cutting mechanism in a single cut includes:

[0019] Obtain the rated torque, saw blade outer diameter, longitudinal travel speed, and empirical coefficients for correcting the uniaxial compressive strength of the surrounding rock and cutting resistance of the double cantilever symmetrical cutting mechanism.

[0020] The numerator is obtained by multiplying the empirical coefficient for correcting cutting resistance by the rated torque, and the denominator is obtained by multiplying the uniaxial compressive strength of the surrounding rock, the longitudinal travel speed, and the outer diameter of the saw disc.

[0021] Dividing the numerator by the denominator yields the upper limit of the single-layer cutting depth, which controls the single-cut depth of the double-cantilever symmetrical cutting mechanism to not exceed the upper limit.

[0022] Preferably, in the contour pre-cutting and end vibration damping boundary construction steps, the position setting method for forming the two vertical isolation grooves is as follows:

[0023] Obtain the lateral vibration margin of the double cantilever symmetrical cutting mechanism and the preset system reference tolerance value, and use the sum of the two as the tolerance compensation amount;

[0024] Using the central axis of the central ditch as a reference, the cutting guide lines on the left and right sides are shifted away from the central axis by a tolerance compensation amount. Then, the double cantilever symmetrical cutting mechanism is controlled to perform the cutting operation along the shifted cutting guide lines.

[0025] Preferably, the double cantilever symmetrical cutting mechanism includes a support and locking assembly, which, during the cutting step:

[0026] Before controlling the double cantilever symmetrical cutting mechanism to cut the rock mass, the control support locking component extends downward and abuts against the bedrock of the tunnel floor and is locked in place;

[0027] In the locked state, the double cantilever symmetrical cutting mechanism is controlled to perform multiple rounds of stepped cutting from top to bottom.

[0028] Preferably, in the drilling and controlled blasting steps, the side holes are arranged in a direction parallel to the vertical isolation groove, and the process of determining the blasting resistance line of the side holes includes:

[0029] Obtain the nominal diameter of the explosive, the charge density, the tensile strength of the surrounding rock, and the empirical coefficient of rock resistance;

[0030] Multiply the rock resistance empirical coefficient, the nominal diameter of the explosive, and the charge density, and then divide by the tensile strength of the surrounding rock to obtain the blasting resistance line value of the side hole. The drilling equipment is then controlled based on this value.

[0031] Preferably, in the drilling and controlled blasting steps, the process for determining the lower limit of the delayed initiation time for the controlled blasting network configuration includes:

[0032] Obtain the horizontal geometric distance between the central cut hole and the side cut holes, the explosive crack propagation rate of the rock mass, and the time taken for rock block movement;

[0033] The initial delay is obtained by dividing the horizontal geometric spacing by the explosive crack propagation rate.

[0034] The lower limit of the delayed detonation time is obtained by adding the initial delay to the time taken for rock movement.

[0035] Preferably, the controlled blasting network includes a detonation controller, a safety interlocking unit, and a digital electronic detonator, and the controlled detonation process includes:

[0036] The safety interlocking unit collects signals from the blasting period at the working face of the main excavation operation system;

[0037] The timing of the detonation signal configured for the central ditch will be compared and verified with the blasting time signal. After the verification is successful, the detonation controller will send a detonation command to the digital electronic detonators arranged in the central rock mass.

[0038] Preferably, in the drilling and controlled blasting steps, vibration-damping holes are drilled in the central rock mass at both ends of the two vertical isolation trenches, and the interior of the vibration-damping holes is kept unloaded.

[0039] Preferably, in the process of waste removal and system advancement, the main waste removal time window of the main excavation operation system is obtained;

[0040] Based on the volume of rock debris from single-cycle blasting in the central water ditch and the rated speed of the cleaning equipment, the time required for rock debris removal is obtained.

[0041] The control and removal equipment synchronously performs the removal of rock debris within the time span of the main slag discharge time window.

[0042] This invention also provides a step-by-step precision excavation system for deep-buried central drainage ditches in hard rock tunnels, used to perform the above-mentioned construction method, comprising:

[0043] The main excavation system is used to perform conventional excavation and support of the tunnel face and invert.

[0044] The independent working platform for the drainage ditch is located on the inverted bedrock behind the main excavation system, maintaining a longitudinal separation distance from the inverted working face;

[0045] The double cantilever symmetrical cutting mechanism, mounted on an independent working platform for the ditch, is used to simultaneously open two vertical isolation trenches in the bedrock;

[0046] A controlled blasting network is deployed within the central rock mass between two vertical isolation channels to perform rock mass detonation.

[0047] This invention provides a method for the step-by-step, precise excavation of a central drainage ditch in a deep-buried hard rock tunnel. It offers the following advantages:

[0048] 1. This invention calculates the longitudinal separation distance between the independent working platform of the water ditch and the working face of the invert arch, and simultaneously removes blasted rock debris within the main tunnel muck removal time window, so that the construction of the central water ditch and the main line excavation do not interfere with each other in physical space and are synchronized in operation scheduling, reducing the idle waiting time of equipment and improving the overall cycle advance efficiency of the tunnel.

[0049] 2. This invention utilizes a double cantilever symmetrical cutting mechanism to pre-open vertical isolation grooves on both sides of the central ditch, and drills vibration-damping holes without explosives at the longitudinal ends, cutting off the continuity between the central rock mass and the external bedrock, causing the blasting stress wave to be reflected at the isolation groove, greatly reducing the vibration transmitted to the bottom plate, controlling the accuracy of the forming contour and reducing over- and under-excavation phenomena.

[0050] 3. This invention quantitatively calculates the upper limit of single-layer cutting depth, blasting resistance line, and delayed detonation time based on surrounding rock mechanical parameters and equipment rated parameters, preventing the cutting equipment from getting stuck in hard rock and optimizing the rock mass fragmentation effect; at the same time, the detonation signal is time-sequenced through a safety interlocking unit, avoiding accidental detonation at the intersection of the main line and the ditch working face, thus ensuring construction safety. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the overall layout of the hard rock tunnel spatiotemporal collaborative excavation system according to an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram illustrating the step-by-step synchronous operation process of tunnel invert arch excavation and deep-buried central water ditch cutting according to an embodiment of the present invention;

[0053] Figure 3 This is a sequence diagram of the contour pre-cutting steps according to an embodiment of the present invention;

[0054] Figure 4 This is a cross-sectional view of the blasting in an embodiment of the present invention;

[0055] Figure 5 This is a diagram showing the layout of the blast holes according to an embodiment of the present invention;

[0056] Figure 6 This is a sequence diagram of the progress of the slag removal and excavation system according to an embodiment of the present invention;

[0057] Figure 7 This is a comprehensive data diagram illustrating the configuration logic and experimental verification of the central drainage ditch excavation parameters in an embodiment of the present invention.

[0058] Among them, 10 is the main line excavation operation system; 20 is the independent operation platform for the ditch; 30 is the double cantilever symmetrical cutting mechanism; and 40 is the controlled blasting network. Detailed Implementation

[0059] 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.

[0060] Figure 1 This is a schematic diagram of the overall layout of a hard rock tunnel spatiotemporal collaborative excavation system according to an embodiment of the present invention.

[0061] This invention provides a step-by-step precise excavation method for deep-buried central drainage ditches in hard rock tunnels. This technical solution is implemented in conjunction with a spatiotemporal collaborative excavation system for hard rock tunnels.

[0062] The hard rock tunnel spatiotemporal collaborative excavation system includes a main line excavation operation system 10, a drainage ditch independent operation platform 20, a double cantilever symmetrical cutting mechanism 30, and a controlled blasting network 40.

[0063] The main excavation system 10 is set up at the tunnel face and invert arch operation area.

[0064] The main excavation system 10 is configured to perform full-section drilling and blasting in front of the tunnel and excavation and pouring of the invert arch behind it.

[0065] The independent working platform 20 for the drainage ditch is arranged longitudinally along the tunnel, behind the tunnel face and in front of the invert working area of ​​the main excavation system 10, and maintains a preset distance from the invert working face.

[0066] In this embodiment, the independent working platform 20 for the drainage ditch is an equipment carrying platform capable of moving and positioning along the longitudinal direction of the tunnel, including a movable supporting base, a support and locking assembly, and an equipment carrying section. The walking part of the movable supporting base and the support and locking assembly are respectively supported on the retained rock masses on both sides of the design outline of the central drainage ditch. The equipment carrying section spans both sides of the design outline of the central drainage ditch and forms working openings at the corresponding positions of the central rock masses to be excavated for cutting heads and drilling equipment to perform cutting and drilling operations.

[0067] The support locking assembly is used to lock the movable support underframe to the bottom of the tunnel during cutting and drilling operations;

[0068] Before detonation, the support locking components are unlocked, allowing the independent working platform 20 in the ditch to be evacuated along with its equipment to a safe blasting avoidance position.

[0069] The current central ditch construction section corresponding to the independent ditch operation platform 20 is defined as the independent ditch operation area.

[0070] The preset distance is 3 to 4 times the standard advance length of the invert arch in the main line excavation system 10.

[0071] The independent working platform 20 for the drainage ditch and the invert working area of ​​the main excavation system 10 are staggered along the longitudinal direction of the tunnel and maintain a safe blasting distance from the tunnel face working area. This creates an independent working space that is staggered along the tunnel axis and can be operated according to the construction sequence between the tunnel face working area, the independent working area for the drainage ditch and the invert working area.

[0072] The double cantilever symmetrical cutting mechanism 30 is movably deployed on the independent working platform 20 of the ditch.

[0073] The double cantilever symmetrical cutting mechanism 30 includes a walking chassis, support and positioning components disposed on both sides of the walking chassis, two hydraulic cantilever arms that can be lifted and adjusted laterally respectively, and cutting heads disposed at the ends of the two hydraulic cantilever arms respectively.

[0074] The two hydraulic cantilever arms are configured to adjust the lateral spacing between the two cutting heads according to the design width of the central ditch, and cut the rock mass downward along the design boundaries on both sides of the ditch, thereby forming two parallel vertical isolation grooves.

[0075] The controlled blasting network 40 is deployed within the rock mass between two vertical isolation channels.

[0076] The controlled blasting network 40 includes electronic detonators, detonation connection lines, detonation controllers, and safety interlocking units. The independent ditch work platform 20 is also equipped with drilling equipment for forming blast holes and charging equipment for loading explosives into the blast holes.

[0077] The drilling equipment is used to drill holes in the core rock mass between vertical isolation trenches in sections, and the controlled blasting network 40 is used to implement micro-delay detonation of the blast holes in different sections according to the set detonation sequence and delay time.

[0078] The collaborative workflow of the step-by-step precise excavation construction method for deep buried central drainage ditches in hard rock tunnels, combined with the excavation system, includes the following steps in both time and space dimensions:

[0079] S10, Construction preparation and spatial pre-positioning are carried out on the independent working platform 20 of the ditch. The movable section of the middle part of the temporary crossing facility covering the working position of the central ditch within the area of ​​the independent working platform 20 of the ditch is moved to the avoidance position, and the lateral passage or bypass passage is kept unobstructed. The work site is cleared, and the surveyors lay out the boundary lines on both sides according to the design outline of the deeply buried central ditch and establish the cutting guide line.

[0080] S20, the double cantilever symmetrical cutting mechanism 30 is started to perform contour pre-cutting and end vibration reduction boundary construction process, so that the cutting operation period of the double cantilever symmetrical cutting mechanism 30 at least partially overlaps with the period of the main line excavation operation system 10 performing invert arch slag removal and support.

[0081] The double cantilever symmetrical cutting mechanism 30 cuts downward along the cutting guide line, forming continuous vertical isolation grooves on both sides of the ditch; the drilling equipment forms an end vibration damping boundary composed of vibration damping holes at the longitudinal front end of the single cycle section, and uses the ditch cavity already excavated in the previous cycle as the longitudinal rear end free boundary of the current cycle.

[0082] For the first excavation cycle, the drilling equipment forms end vibration damping boundaries at the longitudinal front end and longitudinal rear end of the cycle, respectively;

[0083] The vertical isolation trough still retains a through clearance after deducting the thickness of residual rock debris in the trough, the deformation of the trough wall, and the lateral displacement caused by blasting.

[0084] The longitudinal advance length of the pre-cutting process is equal to the standard advance length of the single cycle of the invert arch;

[0085] After the cutting is completed, the double cantilever symmetrical cutting mechanism 30 is moved to the avoidance area, and the area above the blasting operation area is kept open or only the bypass facilities located outside the blasting influence range are restored to pass.

[0086] S30, the controlled blasting network 40 is activated to perform the zoned micro-differential blasting procedure. The drilling and charging operation period of the control center ditch overlaps at least partially with the drilling and charging operation period of the main line excavation operation system 10 at the tunnel face.

[0087] The blasting operations in the central ditch and the blasting operations at the working face are controlled by a unified blasting dispatch command and a safety interlocking unit. They are blasted in the same blasting warning time window in a predetermined order, and the safety interlocking unit is configured to prevent the other blasting controller from entering the blasting state when one of the blasting controllers is in the blasting state.

[0088] The controlled blasting network 40 implements micro-delay blasting in the order of first detonation of the central cut hole and delayed detonation of the side holes, and retains a bottom protective layer between the bottom of the blast hole and the designed bottom elevation of the central ditch for subsequent mechanical finishing; the vertical isolation groove reflects and attenuates the blasting stress wave propagating to its wall, thereby weakening the propagation of blasting stress to the remaining rock mass outside the groove;

[0089] S40, the process of transporting excavated soil and waste is carried out. During the main excavation time window when the main excavation operation system 10 is carrying out excavation operations at the tunnel face, the ditch excavation machinery is started and the broken rock mass in the independent operation area of ​​the ditch is cleared and transported out through the lateral passage, bypass passage or time-sharing passage during the main excavation time window.

[0090] After the rock debris was removed, the reserved bottom protective layer was mechanically repaired and the bottom elevation and side wall contour of the central ditch were inspected.

[0091] After the current cycle passes the acceptance test, the independent working platform 20 and its auxiliary equipment are moved forward along the tunnel longitudinally to the next working section.

[0092] The following section will provide a detailed explanation of the core structures, physical boundary construction mechanisms, and parameter settings involved in the method and system, in conjunction with specific accompanying drawings.

[0093] Reference Figure 2 , Figure 2 This is a schematic diagram of the synchronous operation process of tunnel invert arch excavation and deep-buried central drainage ditch cutting in stages according to an embodiment of the present invention.

[0094] In practice, step S10 is performed to separate the working environment and establish the construction benchmark, thereby reducing the mutual interference of large machinery in different processes within the same cross section.

[0095] The specific implementation process of step S10 includes steps S101 to S103.

[0096] S101, establish the longitudinal spatial position of the independent working platform 20 for the ditch.

[0097] On the longitudinal section of the tunnel axis, the excavation area of ​​the deep central ditch is moved forward, so that the independent ditch operation platform 20 is arranged behind the tunnel face and in front of the invert arch operation area of ​​the main line excavation operation system 10.

[0098] From the perspective of operational principles, this spatially forward-positioned layout can avoid the congested areas of the tunnel invert construction face.

[0099] To reduce overlap between the invert construction machinery of the main excavation system 10 and the cutting equipment on the independent ditch work platform 20 within the working rotation range, the independent ditch work platform 20 is set behind the tunnel face and in front of the invert working face, and its advance distance relative to the invert working face is matched with the invert construction progress.

[0100] The longitudinal separation distance between the independent ditch work platform 20 and the main line excavation system 10 on the invert arch construction face. The following relationship must be satisfied:

[0101] ;

[0102] In the formula, The longitudinal separation distance of the independent working platform 20 of the ditch relative to the working surface of the inverted arch;

[0103] This refers to the standard advance length of the invert arch in a single cycle corresponding to the longitudinal separation distance.

[0104] The standard advance length of the invert arch in the main excavation system 10 for a single cycle. Select from the range of 3 to 4;

[0105] When setting the specific value of N, the longitudinal separation distance should not be less than the sum of the longitudinal occupancy length of the double cantilever symmetrical cutting mechanism 30 and the independent ditch working platform 20 and the front and rear safety buffer distances, that is:

[0106] ;

[0107] In the formula, The maximum length occupied by the independent working platform 20 for the drainage ditch and its working equipment along the longitudinal direction of the tunnel;

[0108] Provide a safe buffer distance for the platform's front end;

[0109] Provides a safe buffer distance for the platform's backend.

[0110] Only when Only when the above-mentioned equipment space conditions are met simultaneously, taking options 3 to 4, can the following conditions be met: The value is determined to be 3 to 4.

[0111] Determined according to the following relationship:

[0112] ;

[0113] In the formula, the symbol This indicates rounding up. When determined according to the above relationship... When the value is not greater than 4, the determined value shall be used. ;

[0114] When calculated When the value is greater than 4, it indicates that the longitudinal occupancy length of the independent ditch working platform 20 and its working equipment is not suitable for the spatial arrangement of 3 to 4 cycles of advance as defined in this embodiment. It is necessary to shorten the longitudinal occupancy length of the equipment, reduce the safety buffer distance, or adjust the structural arrangement of the independent ditch working platform 20 before construction can proceed.

[0115] With this layout, the excavation face of the central ditch is physically separated from the interference zone in conventional assembly line construction, forming a basis for parallel subsequent mechanical operations.

[0116] S102, Perform site cleanup in area 20 of the independent working platform for the drainage ditch.

[0117] Remove the temporary crossing facilities covering the independent working platform 20 of the ditch.

[0118] Because it is necessary to keep the muck removal channel at the front face unobstructed during hard rock tunnel construction, temporary crossing facilities usually use steel structure trestle bridges.

[0119] The control and traction equipment will move the temporary crossing facility longitudinally along the tunnel to a clearance position outside the current independent operation area of ​​the drainage ditch, so that the bedrock surface of the reserved central drainage ditch below is exposed, and physical obstacles affecting subsequent downward cutting, drilling and slag removal operations are eliminated.

[0120] The specific support structure and traction movement method of the temporary crossing facility can be conventionally configured according to the tunnel cross-sectional dimensions by those skilled in the art, which is well known in the field and will not be described in detail here.

[0121] After the temporary crossing facility is moved to the avoidance position, it shall not be restored to the position directly above the rock mass to be blasted until the pre-cutting, drilling and charging, detonation, post-blast inspection and slag removal in the ditch are completed.

[0122] Mainline transport is maintained through bypass passages located on one or both sides of the central ditch;

[0123] Alternatively, the temporary crossing facility may adopt a segmented structure, moving only the middle crossing section corresponding to the current independent operation area of ​​the ditch, while retaining the lateral passage section located outside the blasting impact range.

[0124] S103, establish the reference drilling position and cutting guide line.

[0125] On the bedrock surface of the cleaned independent working platform 20 for the ditch, coordinate layout is carried out according to the pre-designed outline of the deep-buried central ditch.

[0126] Surveyors used a total station to mark the longitudinal center axis of the ditch and laid it out laterally to both sides to establish two parallel cutting guide lines.

[0127] The lateral coordinates of the left-side cutting guide line satisfy:

[0128] ;

[0129] The lateral coordinates of the right-side cutting guide line satisfy:

[0130] ;

[0131] In the formula, The horizontal coordinate of the left-side cutting guide line;

[0132] The horizontal coordinate of the cutting guide line on the right;

[0133] The transverse coordinate of the longitudinal central axis of the central ditch;

[0134] The design net width for the deeply buried central drainage ditch;

[0135] δ is the mechanical cutting tolerance compensation amount set out from the design boundary of the ditch outward.

[0136] In actual operation, if the cutter head is cut directly along the boundary of the designed net width, the thickness of the cutter head itself will occupy the internal space of the water channel, resulting in the actual distance between the two sides of the interface after the central rock mass is removed.

[0137] Therefore, tolerance compensation amount The value is usually set to the sum of half the thickness of the cutter head and the lateral vibration margin of the equipment.

[0138] As a specific example, if the blade thickness of the selected cutting equipment is calibrated to 30 mm, and the equipment vibration margin is measured to be 5 to 10 mm through on-site test cutting, then the tolerance compensation amount is... The value range can be determined to be 20 to 25 millimeters.

[0139] By applying physical markers to the rock surface to determine the offset position, a continuous cutting guide line is formed, providing a cutting reference for the double cantilever symmetrical cutting mechanism 30.

[0140] Positioning markers are set at intervals along the cutting guide line according to the undulation of the bedrock surface, for checking the cutting position and travel direction of the double cantilever symmetrical cutting mechanism 30;

[0141] Between the two cutting guide lines, a blast hole positioning grid is formed based on the design coordinates of the center slot and the side row holes, and the reference drilling positions of the center slot, the side row holes and the end vibration damping holes are marked respectively.

[0142] Reference Figure 3 , Figure 3 This is a contour pre-cutting step sequence diagram according to an embodiment of the present invention.

[0143] After completing the spatial positioning and guide line layout, step S20 is executed to cut parallel vertical isolation grooves in the rock mass of both sides of the boundary line to construct a physical wave-damping boundary for subsequent blasting operations.

[0144] The specific implementation process of step S20 includes steps S201 to S204.

[0145] S201, control the double cantilever symmetrical cutting mechanism 30 to enter the independent working platform 20 of the ditch and perform anti-sway positioning.

[0146] The double cantilever symmetrical cutting mechanism 30 includes a heavy-duty traveling chassis, hydraulic cantilever arms arranged symmetrically on both sides, and a diamond saw disc installed at the end of the hydraulic cantilever arms.

[0147] In actual engineering, when excavating hard rock with a compressive strength greater than 100MPa, the diamond saw disc is easily affected by the heterogeneity of the rock mass, resulting in lateral load, which in turn leads to the bending deformation of the cutter disc or even jamming of the saw.

[0148] To address this issue, the lateral degree of freedom of the diamond saw blade is locked by activating the hydraulic lock-up valve and hydraulic locking circuit within the hydraulic cantilever, thus limiting its lateral disturbance in the cutting guide plane.

[0149] Setting the maximum permissible lateral deflection during diamond saw cutting The following conditions must be met:

[0150] ;

[0151] In the formula, Peak lateral resistance;

[0152] : Lateral equivalent stiffness after locking;

[0153] : Width of the vertical isolation groove;

[0154] This is the offset tolerance factor, which typically ranges from 0.1 to 0.15.

[0155] Technicians can calculate and estimate the peak lateral resistance based on the previous core sampling data, and adjust the back pressure of the hydraulic system to set the lateral equivalent stiffness to ensure that the deflection is controlled within the safe threshold.

[0156] The specific drive transmission structure and conventional layout of the hydraulic pipelines of the chassis can be conventionally configured according to the power supply conditions in the tunnel, which is a well-known technology in the field and will not be described in detail here.

[0157] S202 performs a top-down stepped pre-cutting operation.

[0158] The double cantilever symmetrical cutting mechanism 30 is controlled to move synchronously along the longitudinal direction and drive two sets of diamond saw discs to cut in layers along the cutting guide line.

[0159] To prevent damage to the cutter head due to overload from a single deep cut, the single-layer cutting depth for each cut is... The configuration is determined based on the mechanical properties of the target rock and the equipment's dynamic parameters:

[0160] ;

[0161] In the formula, The empirical coefficient for correcting cutting resistance is determined based on the degree of development of rock strata, and is usually taken as 0.6 to 0.85 for slightly weathered, intact, and hard rock sections;

[0162] The rated torque output of the double cantilever symmetrical cutting mechanism 30;

[0163] The uniaxial compressive strength of the rock;

[0164] This refers to the longitudinal travel speed of the equipment; This refers to the outer diameter of the diamond saw blade.

[0165] The engineering principle behind this calculation formula is to use the rated mechanical power provided by the equipment to balance the energy consumption required for rock breaking, thereby solving for the maximum safe feed rate under the current rock type while preventing spindle torque overload.

[0166] The double cantilever symmetrical cutting mechanism 30 performs multiple rounds of longitudinal reciprocating travel and layer-by-layer downward feeding based on a determined single-layer cutting depth until the bottom of the vertical isolation groove reaches the design bottom elevation of the central water ditch.

[0167] During the equipment selection and trial cutting phase, the geometric relationships between the diamond saw disc, spindle, saw disc guard, and hydraulic cantilever are verified in advance to ensure that the maximum effective cutting depth of the diamond saw disc is not less than the design depth of the vertical isolation groove.

[0168] ;

[0169] In the formula, To determine the maximum effective cutting depth achievable after considering the saw blade radius, spindle position, guard size, and cantilever extension stroke;

[0170] This refers to the design depth of the vertical isolation groove.

[0171] In this embodiment, the double cantilever symmetrical cutting mechanism 30 is selected to meet the requirements. The diamond saw disc and its matching hydraulic cantilever are used. When the maximum effective cutting depth of the selected diamond saw disc cannot meet the above conditions, the diamond saw disc will not be used to perform the vertical isolation groove cutting operation of this embodiment.

[0172] This stepped feed method distributes the cutting load of the entire rock mass across multiple working strokes.

[0173] S203, flushing and slag removal and establishing physical boundaries that conform to wave-damping parameters.

[0174] After the stepped cutting is completed, two vertical isolation channels are formed on both sides of the central ditch.

[0175] Vertical isolation trenches are used to weaken the main path of blasting stress waves that propagate directly laterally between the deep-buried central drainage ditch area and the main rock mass preserved in the tunnel floor, and to cause the blasting stress waves propagating to the trench wall to be reflected, diffracted and attenuated.

[0176] The width of the vertical isolation groove is... Its size configuration is designed to meet the requirements for blocking the lateral impact of subsequent internal blasting.

[0177] The width of the vertical isolation trench Configured to maintain a minimum clearance for continuity even after considering lateral expansion of the central rock mass from blasting, residual rock debris within the trench, and deformation of the trench walls, it satisfies the following:

[0178] ;

[0179] In the formula, The estimated value of the maximum lateral expansion displacement of the central rock mass toward the vertical isolation trench under controlled blasting.

[0180] It is the sum of the allowable residual rock debris thickness in the vertical isolation trench after high-pressure washing and the amount of trench wall deformation closure;

[0181] This refers to the minimum through clearance width that the vertical isolation trench should maintain during the blasting process.

[0182] The and The width of the vertical isolation trench is determined by small-scale blasting tests under the same or similar geological conditions, based on the minimum net width measured after flushing and slag removal.

[0183] The thickness of the diamond saw disc, the end face runout, the lateral vibration of the equipment, and the number of repeated cuts are comprehensively configured to ensure that the measured minimum net width satisfies the above relationship.

[0184] During and after the cutting process, the high-pressure water jet built into the equipment is activated to flush the inside of the gap under high pressure, remove the deposited rock debris, and ensure that the physical boundary has the cavity impedance characteristics of a cavity without medium filling.

[0185] In addition to the vertical isolation trenches on both sides, a row of vibration-damping holes is installed transversely along the front longitudinal direction of each trench excavation cycle. The bottom of the vibration-damping holes reaches the bottom elevation of the vertical isolation trenches. The spacing between adjacent vibration-damping holes is configured to allow burst cracks to preferentially penetrate between adjacent vibration-damping holes. The diameter of the vibration-damping holes is denoted as [missing information]. The net distance between adjacent vibration damping holes is denoted as . .

[0186] In one embodiment, the net distance between holes satisfies:

[0187] ;

[0188] The specific diameter and spacing of the vibration-damping cavities can be adjusted based on the results of test drilling and small-charge test blasting in similar surrounding rock to create a continuous or nearly continuous crack weakening zone between adjacent cavities.

[0189] The longitudinal rear end of the current cycle is used as the free boundary of the ditch cavity that has been excavated in the previous cycle.

[0190] For the first excavation cycle, the aforementioned damping holes are set at the longitudinal front end and longitudinal rear end of the first cycle, so that the core rock mass to be blasted in a single cycle forms a controlled boundary in the longitudinal direction of the tunnel.

[0191] S204, completion process time coordination.

[0192] The pre-cutting operation of the double cantilever symmetrical cutting mechanism 30 can be carried out in parallel with the invert slag removal and initial support operations performed by the main excavation system 10 behind it, at least partially within the same operation time window.

[0193] Longitudinal feed length of a single pre-cutting process The single-cycle advance length of the invert arch of the main excavation system 10 Maintain synchronized matching.

[0194] After the vertical isolation trench of the corresponding length is opened, the double cantilever symmetrical cutting mechanism 30 is controlled to retreat along the original route to the forward avoidance area. The movable section in the middle of the temporary crossing facility covering the central ditch operation position will not be restored for the time being. Mainline vehicles can pass through the side passage, bypass passage or pass through the construction scheduling instructions in stages.

[0195] After the blasting operation in step S30 and the slag removal and base trimming operation in step S40 are completed, the central movable section is restored to the passable position.

[0196] By arranging operations at the same frequency and within the same window, the time spent on mechanical pre-cutting operations is at least partially included in the time spent on invert arch slag removal and support operations, thereby reducing the additional time occupied by ditch cutting operations on the critical construction period of the tunnel main line.

[0197] See attached document Figure 4 , Figure 4 This is a blasting cross-section diagram according to an embodiment of the present invention.

[0198] See attached document Figure 5 , Figure 5 This is a diagram showing the layout of blast holes according to an embodiment of the present invention.

[0199] After completing the pre-cutting operation of the double cantilever symmetrical cutting mechanism 30, step S30 is executed.

[0200] A controlled blasting network 40 is deployed in the central rock mass between two vertical isolation channels to perform zoned micro-differential blasting procedures.

[0201] From a construction operation perspective, this step aims to use isolation boundaries to confine the blasting energy within the outline of the ditch, thereby reducing disturbance to the main rock mass of the outer bottom plate.

[0202] The specific implementation process of step S30 includes steps S301 to S304.

[0203] S301 performs spatial arrangement and drilling operations for the blast hole array.

[0204] In the central rock mass between the two vertical isolation channels, central cut-out holes and side drainage holes are arranged.

[0205] Both the central cut hole and the side drain hole are drilled downwards from the bedrock surface at the top of the central ditch. The axis of the blast hole is set along the depth direction of the ditch and is basically parallel to the depth direction of the vertical isolation trench.

[0206] The bottom of the central cutout and the side drain holes are located at a predetermined distance above the designed bottom elevation of the central drainage ditch, so as to retain a protective layer at the bottom of the ditch. The thickness of the protective layer is denoted as . .

[0207] The thickness of the protective layer is determined based on the integrity of the surrounding rock, the error at the bottom of the blast hole, and the allowable over-excavation of the ditch. In one embodiment, it is taken as 100 mm to 300 mm.

[0208] After the central rock mass is blasted and the slag is removed, the protective layer is removed using a hydraulic breaker, a mechanical milling head, or a small cutting device, so that the base of the ditch reaches the designed bottom elevation.

[0209] The central cut-out holes are located in the central axis area of ​​the central rock mass.

[0210] The side-row eyes are arranged in vertical isolation grooves parallel to both sides.

[0211] The lateral distance from the center of the side hole to the inner wall of the vertical isolation groove is set as the blast resistance line. .

[0212] The value of is determined by the following formula:

[0213] ;

[0214] In the formula, The empirical coefficient for rock resistance is set to 1.2 to 1.5 for slightly weathered hard rock. The diameter of the cylinder of the selected explosive cartridge;

[0215] In one specific embodiment of the invention, the charge density of the explosive is... and The value is usually taken directly from the nominal specifications of the standardized industrial emulsion explosives or water-gel explosives purchased on site.

[0216] The tensile strength of the core rock mass can be obtained through uniaxial tensile tests of the rock core during the early geological exploration stage.

[0217] In the principle of rock breaking by blasting, the setting of the blasting resistance line needs to balance the work capacity released by the explosive explosion with the tensile strength limit of the rock itself.

[0218] The drilling equipment, set on the independent working platform 20 of the ditch, completes the drilling operations of the central slot and the side slots according to these parameters.

[0219] As a preferred implementation, the blast array is constructed by configuring these parameters so that the energy generated by the blast is sufficient to overcome the rock binding force and break the rock, while reducing the risk of excessive blast energy impacting the rock mass outside the vertical isolation trench.

[0220] For the specific selection of drilling equipment and the routine control of drilling depth, those skilled in the art can make routine configurations based on the tunnel cross-section dimensions. These are well-known technologies in the field and will not be elaborated here.

[0221] S302, construct a controlled blasting network 40 and execute the detonation control of the central cut hole.

[0222] After the charging operation is completed inside the borehole, the electronic detonator initiation communication line of the controlled blasting network 40 is connected and the initiation delay time is configured.

[0223] The controlled blasting network 40 is configured to detonate the first hole in the control center.

[0224] Before detonation, release the support and locking status of the independent ditch operation platform 20, and allow the independent ditch operation platform 20, together with the double cantilever symmetrical cutting mechanism 30, drilling equipment and charging equipment, to be moved to a safe blasting avoidance position.

[0225] The central movable section of the temporary crossing facility remains outside the blasting impact area, and construction personnel withdraw from the blasting warning zone.

[0226] The central ditch detonation controller and the working face detonation controller are interlocked through a safety interlocking unit. Only after both blasting areas have been cleared and the detonation conditions have been met can the detonation be carried out in a predetermined order within a unified blasting warning time window. At any given time, only one of the central ditch detonation controller and the working face detonation controller is allowed to enter the detonation state.

[0227] The engineering principle is that, since the main free surface of the central rock mass is located at the top, the vertical isolation grooves on both sides form the horizontal unloading boundary and the stress wave attenuation boundary. After the central slot is detonated, the blasting stress wave and the high-pressure explosive gas crush the rock in the center of the central rock mass, throwing the original solid rock mass upward, thus forming a through initial free surface in the central area between the two vertical isolation grooves.

[0228] This initial free surface provides expansion space for the rock fragments broken by subsequent side-hole blasting.

[0229] S303, executes delayed detonation control to prevent the side holes from collapsing inward.

[0230] The controlled blasting network 40 is configured to detonate in the central cut hole after a predetermined delay time. The outer edge of the detonation hole.

[0231] At the hardware implementation level, this delay logic can be achieved by filling the hole with a high-precision digital electronic detonator and writing the corresponding micro-delay parameter into it.

[0232] Extension time The settings are configured to allow the rock cracks in the first center cut hole to be fully penetrated and the core fragments to be ejected.

[0233] The lower threshold is determined according to the following formula:

[0234] ;

[0235] In the formula, The horizontal geometric distance between the center cut hole and the side row holes is determined by the row spacing design parameters of the blast holes.

[0236] The current explosive crack propagation rate in hard rock media can be obtained by combining rock dynamics and statics test results with acoustic wave test results.

[0237] The time it takes for the rock fragments at the center to be ejected by high-pressure gas and form an effective cavity can be obtained by high-speed video recording of a small-volume throwing test in the field, with the value range configured from 20 milliseconds to 50 milliseconds.

[0238] The delayed detonation principle of the side-row hole is to guide the remaining rock blocks to collapse towards the central cavity area under the action of the initial free surface, and to use the spatial compensation mechanism to block the tendency of the rock fragments to expand outward to both sides, thus preventing them from squeezing the pre-cut vertical isolation groove.

[0239] S304, Perform post-explosion safety and profile checks.

[0240] After completing the micro-delay detonation of the central cut hole and the side drain hole, forced ventilation was carried out in the central water ditch operation area, and the concentration of blasting smoke and harmful gases was detected.

[0241] After the conditions for personnel entry are met, the blasting personnel shall check for misfires, unexploded ordnance detonators, and undetonated charge holes, and handle the misfires in accordance with the blasting safety operation procedures.

[0242] After confirming that there are no misfires, check whether the vertical isolation trenches on both sides remain connected, remove loose rocks from the trench walls and the central ditch, and measure the lateral position and verticality of the ditch sidewalls after blasting, as well as the elevation of the bottom surface of the blasted rock mass.

[0243] The slag removal operation in step S40 is only permitted after the post-blast safety inspection is completed and the blasting warning is lifted.

[0244] See attached document Figure 6 , Figure 6 This is a sequence diagram of the progress of a slag removal and excavation system according to an embodiment of the present invention.

[0245] After the directional unloading blasting operation of the central rock mass is completed, step S40 is executed, in which the broken rock blocks are removed by means of the time-space reuse mechanism through the existing logistics channel of the tunnel, and the excavation system is advanced into the next construction cycle.

[0246] The specific implementation process of step S40 includes steps S401 to S402.

[0247] S401, execute time-aligned scheduling of waste soil transportation.

[0248] The blasted and broken rock fragments in the central ditch area need to be removed from the tunnel in a timely manner. At the same time, the main excavation system 10 also faces the slag removal process after blasting at the front face.

[0249] The scheduling instructions issued by the construction scheduling control unit control the ditch slag removal equipment and the main slag removal equipment of the main line excavation operation system 10 to operate within the same main slag removal time window.

[0250] When the lateral passage or bypass channel has two-way or zoned passage conditions, the two slag discharge devices can operate in parallel;

[0251] When the passage width is insufficient, a muck removal time period and a slag removal time period are set at the working face and in the water ditch within the main muck removal time window, so that the two types of vehicles can alternately pass through the shared transport section.

[0252] The hard rock tunnel spatiotemporal collaborative excavation system also includes a construction scheduling and control unit. The construction scheduling and control unit is used to record the operation time windows of drilling and blasting operations at the tunnel face, invert arch operations, water ditch pre-cutting operations, and water ditch muck removal operations, and to issue operation start, pause, passage switching, and equipment transfer instructions to the corresponding equipment or construction personnel.

[0253] To avoid delays in the main process due to water ditch clearing, the number and loading efficiency of the water ditch slag removal equipment are configured to meet the timing envelope conditions.

[0254] Time required to complete the removal of rocks from the ditch The following constraints must be met:

[0255] ;

[0256] In the formula, The coefficient of volume expansion of hard rock after blasting;

[0257] The volume of the original rock body excavated by the blasting of the central ditch within a single cycle;

[0258] The overall rated loading and transportation rate of the slag removal equipment in the ditch;

[0259] The actual available time allocated to slag removal operations in the ditch within the main slag removal time window;

[0260] The main slag removal operation time window is set by the main excavation operation system 10.

[0261] Technicians calculate the blasting volume and adjust the configuration. This ensures that the slag removal operation in the ditch is at least partially within the main slag removal time window of the main line slag removal operation on the time axis, and adopts parallel or time-sharing passage methods according to the width of the channel.

[0262] The slag removal equipment in the ditch and the slag removal equipment at the tunnel face can share the external transport fleet and part of the internal transport section, or they can be equipped with separate loading equipment.

[0263] This scheduling logic avoids additional equipment overlap and vehicle waiting caused by ditch excavation, enabling the reuse of construction machinery at the same frequency.

[0264] For the specific selection of loading machinery and heavy transport fleets and the planning of conventional driving routes, those skilled in the art can make conventional configurations based on the tunnel cross-sectional dimensions, which are well-known technologies in the field and will not be elaborated here.

[0265] After the blasted and broken rock blocks are removed, a hydraulic breaker, a mechanical milling head, or a small cutting device is used to remove the protective layer reserved at the bottom of the ditch. The bottom elevation, net width, and sidewall verticality of the central ditch are then re-measured using a total station, laser elevation measuring equipment, or cross-section scanning equipment. Mechanical trimming is implemented for areas with under-excavation.

[0266] For areas of localized over-excavation, filler materials compatible with the ditch structure will be used during subsequent ditch lining construction.

[0267] S402, execute the periodic advancement mechanism of the excavation system.

[0268] After the excavated soil in the area where the independent working platform 20 of the ditch is located is removed and the foundation is leveled with the assistance of manual or mechanical means, the step-by-step precise excavation of the deep-buried central ditch in the current construction section is completed.

[0269] The independent working platform 20 for controlling the water ditch and its associated double cantilever symmetrical cutting mechanism 30 and other supporting equipment are periodically moved longitudinally forward along the tunnel direction.

[0270] Distance of a single longitudinal step The single-cycle advance length of the invert arch of the main excavation system 10 To maintain consistency, satisfying:

[0271] ;

[0272] After the equipment is moved longitudinally, the independent working platform 20 for the ditch is locked in the next ditch working position. The construction scheduling system adjusts the moving time of the independent working platform 20 for the ditch according to the actual advancing position of the invert working face, so that the independent working platform 20 for the ditch and the invert working face continue to maintain a longitudinal separation distance of 3 to 4 invert working cycles.

[0273] After the current cycle of blasting and clearing rock blocks from the ditch, removing the bottom protective layer, and completing the outline inspection are completed, the movable middle section of the temporary crossing facility will be restored to the passable position of the currently completed ditch section. After the independent working platform 20 of the ditch is moved to the next working position, the movable middle section corresponding to the next working position will be moved away to enter the next construction cycle.

[0274] Through this coordinated advancement mechanism with equal step spacing, the construction of the main arch and the construction of the deep-buried water ditch always maintain a safe and non-overlapping isolation distance in physical space, thus forming a closed loop in the overall logic of the project, and preparing to enter the next round of spatial decoupling, cutting and blasting cycle.

[0275] See attached document Figure 7 , Figure 7 This is a comprehensive data diagram of the configuration logic and experimental verification of the central drainage ditch excavation parameters according to an embodiment of the present invention.

[0276] To further clarify the control logic and technical advantages of the step-by-step precise excavation method for deep-buried central drainage ditches in hard rock tunnels described in this invention in actual engineering, a detailed explanation is provided below using a specific application example and field comparative test of deep-buried central drainage ditches in a slightly weathered hard rock tunnel.

[0277] In a tunnel project in a granite stratum, the uniaxial compressive strength of the surrounding rock was... The measured tensile strength is 120 MPa. The measured value was 8 MPa.

[0278] Standard advance length of single cycle for the invert arch of main excavation system 10 Set to 3m.

[0279] The maximum length of the independent ditch work platform 20 and its working equipment deployed on site along the longitudinal direction of the tunnel. The platform front-end safety buffer distance is 5.5m. and backend safety buffer distance They are configured to be 1.5m and 1.0m respectively.

[0280] Technicians calculate the cycle base for the longitudinal separation distance based on the collaborative propulsion control logic.

[0281] ;

[0282] The calculation result is no greater than 4, which meets the physical space requirements of the equipment.

[0283] Therefore, the longitudinal separation distance between the independent working platform 20 of the ditch and the working surface of the invert arch is... Set to 9m.

[0284] This separation distance ensures that the independent working platform 20 of the drainage ditch will not cause spatial interference with the rear arch pouring and the front face drilling and blasting when carrying out a full set of mechanical operations.

[0285] During the pre-cutting process, the designed net width of the central drainage channel... It is 1.2m.

[0286] The selected double cantilever symmetrical cutting mechanism 30 is configured with an outer diameter of The diamond saw disc is 2.0m long and 30mm thick. On-site test cuts determined the equipment's lateral vibration tolerance to be 5mm.

[0287] Based on the tolerance compensation principle, the tolerance compensation amount The calculation is 15mm + 5mm = 20mm.

[0288] Therefore, the left and right cutting guide lines are set at a distance of 0.62m from the central axis.

[0289] To prevent the diamond saw blade from jamming due to the hard rock mass with a strength of 120 MPa, the technicians configured a single-layer cutting depth. .

[0290] The rated torque output by the known equipment 450 longitudinal travel speed The cutting resistance correction empirical coefficient is set to 0.02 m / s. Take 0.8. Single-layer cutting depth The theoretical upper limit is calculated to be 2.

[0291] ;

[0292] The control system rigidly constrains the depth of a single cut to within 75mm, driving the equipment to perform multiple rounds of reciprocating cuts until the designed depth of 1.5m is reached.

[0293] The measured net width of the two vertical isolation grooves formed by the cutting was... The thickness is 35mm, which is greater than the sum of the lateral expansion displacement and the residual thickness of the rock debris, thus meeting the physical wave-damping requirements.

[0294] During the parameter configuration phase of the controlled blasting network 40, a nominal diameter is selected. 0.032m, charge density For a standard chemical industrial emulsion explosive of 1100 kg / m³, the empirical coefficient of rock resistance is... It is 1.3.

[0295] Explosive resistance line of the edge row The calculation is as follows:

[0296] ;

[0297] Based on this, the drilling equipment completes the hole layout on the cross section of the central ditch.

[0298] Regarding the initiation micro-delay time setting, the horizontal geometric distance between the center cut hole and the side cut holes... The design depth is 0.4m. The current explosive crack propagation rate of the granite was measured. The rock movement time was 1500 m / s, obtained from a small-dose test. It takes 25ms.

[0299] Delayed detonation time The lower limit is:

[0300] ;

[0301] The controlled blasting network uses a 30ms delay time to write high-precision digital electronic detonators into the boreholes, ensuring that the core rock fragments are ejected before guiding the side holes to collapse inwards.

[0302] After the explosion, a volume expansion coefficient is generated. Rock slag with a strength of 1.4.

[0303] Single-cycle blasting of original rock volume The rated capacity of the cleaning equipment is 5.4 m³. The capacity is configured to be 60 m³ / h.

[0304] Cleaning time The calculated time is 7.56 minutes, which is much smaller than the main slag discharge time window. The project successfully achieved timeline-aligned scheduling of construction waste without taking up additional critical construction time.

[0305] Based on the aforementioned project background, comparative tests were conducted on-site.

[0306] The control group used the traditional drill and blast method to directly excavate the central ditch without pre-cutting the boundary of the isolation trench.

[0307] The experimental group used the spatiotemporal collaborative excavation system and the step-by-step cutting and blasting method of the present invention.

[0308] Combined with appendix Figure 7 The test data on blasting vibration velocity attenuation was obtained by deploying three-dimensional vibration sensors in the inverted bedrock at distances of 2m, 4m, and 6m from the outer edge of the central ditch design boundary to collect peak particle vibration velocity data during the blasting process.

[0309] Analysis of the collected waveform data revealed that in traditional direct drilling and blasting groups, the peak particle vibration velocity at a distance of 2m from the boundary reached as high as 18.5cm / s. A large amount of blasting energy was transmitted to the outer bottom plate in the form of stress waves, resulting in the propagation of micro-primary cracks inside the main rock mass.

[0310] In the test group where the present invention was implemented, the vertical isolation groove pre-cut by the double cantilever symmetrical cutting mechanism 30 cut off the direct propagation medium of the stress wave, and the difference in wave impedance caused the transmitted dynamic stress to decrease sharply.

[0311] The peak particle vibration velocity at a distance of 2m from the boundary dropped sharply to 3.2cm / s, a decrease of 82%, which fully meets the safety control standards for hard rock blasting and effectively maintains the structural integrity of the load-bearing bottom plate on both sides of the ditch.

[0312] Combined with appendix Figure 7In the contour measurement statistics, after the rock debris in the two test sections was cleared, the surveyors used a three-dimensional laser scanning device to collect and compare the point cloud of the formed central ditch sidewall contour, and extracted the measurement deviation value of the continuous section in the statistical template.

[0313] In the comparative section of conventional direct drilling and blasting, the rock mass was irregularly torn due to the lateral blast impact, and the over-excavation was widely distributed between +80mm and +250mm. There were some areas of under-excavation, which required subsequent manual pneumatic pick trimming, and the standard deviation of the formed profile was extremely large.

[0314] In the test section using the present invention, the controlled blasting of the side-row holes is confined within the pre-cut boundary, and the blast crack terminates along the physical boundary.

[0315] The scan data statistics show that the over-excavation of the sidewall profile is consistently controlled between +20mm and +45mm, and there are no under-excavation points. The frequency distribution is highly concentrated.

[0316] This method utilizes mechanical pre-cutting combined with a micro-differential unloading blasting mechanism to achieve high-precision contour control of deep-buried water ditches in hard rock, avoiding the high cost of concrete backfilling and time-consuming repairs in the later stages.

[0317] In terms of construction organization efficiency, the mechanical cutting operation period is overlapped with the invert arch muck removal support period of the main line excavation operation system 10 through the construction scheduling control unit, and the ditch blasting period is interlocked with the face blasting period.

[0318] The total construction time of the single-cycle water ditch in the test section was completely encompassed within the non-critical path of the main line operation. Compared with the traditional serial construction or cross-interference waiting mode, each advancement cycle saved a lot of waiting window period for the main line operation, realizing mechanized collaborative operation of multiple processes in the whole space in hard rock tunnels.

[0319] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for step-by-step, precise excavation of a central drainage ditch in a deep-buried hard rock tunnel, characterized in that, Includes the following steps: Construction preparation and space pre-planning steps: Establish the longitudinal spatial position of the independent ditch operation platform (20) behind the main excavation operation system (10) of the tunnel, and maintain a longitudinal separation distance between the independent ditch operation platform (20) and the invert arch operation surface; Contour pre-cutting and end vibration damping boundary construction steps: On the independent working platform (20) of the water ditch, the double cantilever symmetrical cutting mechanism (30) is used to cut along the two sides of the central water ditch into the rock mass to form two vertical isolation grooves; Drilling and controlled blasting steps: A central cut-out and a side cut-out are arranged in the central rock mass between the two vertical isolation slots, and a micro-delay detonation is performed through a controlled blasting network (40); Construction waste removal system and implementation steps: The rock debris generated by the blasting of the central ditch is cleared, and the independent working platform (20) of the ditch is moved forward along with the main excavation system (10).

2. The method for step-by-step precise excavation of a deep-buried central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, In the construction preparation and spatial pre-positioning steps, the process of establishing the longitudinal separation distance includes: Obtain the maximum longitudinal length of the independent operation platform (20) and its equipment, as well as the safety buffer distance between the front and rear ends; The initial ratio is obtained by dividing the sum of the maximum occupied length, the safety buffer distance at the front and rear ends by the standard advance length of the single cycle of the invert arch. The maximum value between the preset constant value and the initial ratio is taken and rounded up to obtain the cycle base; The longitudinal separation distance is obtained by multiplying the cycle base number by the standard advance length of the single cycle of the invert arch.

3. The method for step-by-step precise excavation of a deep-buried central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, In the contour pre-cutting and end vibration damping boundary construction steps, the process for determining the upper limit of the single-layer cutting depth of the double cantilever symmetrical cutting mechanism (30) in a single cut includes: Obtain the rated torque, saw blade outer diameter, longitudinal travel speed, and empirical coefficients for correction of uniaxial compressive strength and cutting resistance of the surrounding rock output by the double cantilever symmetrical cutting mechanism (30); The numerator is obtained by multiplying the cutting resistance correction empirical coefficient by the rated torque, and the denominator is obtained by multiplying the uniaxial compressive strength of the surrounding rock, the longitudinal travel speed, and the outer diameter of the saw disc. Divide the numerator by the denominator to obtain the upper limit of the single-layer cutting depth, and control the single cutting depth of the double cantilever symmetrical cutting mechanism (30) to not exceed the upper limit.

4. The method for step-by-step precise excavation of a deep-buried central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, In the contour pre-cutting and end vibration damping boundary construction steps, the position setting method for forming the two vertical isolation grooves is as follows: Obtain the lateral vibration margin of the double cantilever symmetrical cutting mechanism (30) and the preset system reference tolerance value, and use the sum of the two as the tolerance compensation amount; Using the central axis of the central ditch as a reference, the tolerance compensation amount is translated on the left and right cutting guide lines away from the central axis, and then the double cantilever symmetrical cutting mechanism (30) is controlled to perform cutting operations along the translated cutting guide lines.

5. The method for step-by-step precise excavation of a deep-buried central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, The double cantilever symmetrical cutting mechanism (30) includes a support and locking assembly that, during the cutting step: Before controlling the double cantilever symmetrical cutting mechanism (30) to cut the rock mass, control the support locking assembly to extend downward and abut against the bedrock of the tunnel floor to be in a locked state; In the locked state, the double cantilever symmetrical cutting mechanism (30) is controlled to perform multiple rounds of stepped cutting from top to bottom.

6. The method for step-by-step precise excavation of a central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, In the drilling and controlled blasting steps, the side holes are arranged parallel to the vertical isolation groove, and the process of determining the blasting resistance line of the side holes includes: Obtain the nominal diameter of the explosive, the charge density, the tensile strength of the surrounding rock, and the empirical coefficient of rock resistance; Multiply the empirical rock resistance coefficient, the nominal diameter of the explosive, and the charge density, and then divide by the tensile strength of the surrounding rock to obtain the blasting resistance line value of the side hole. Based on this value, control the equipment to perform hole drilling.

7. The method for step-by-step precise excavation of a deep-buried central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, In the drilling and controlled blasting steps, the process for determining the lower limit of the delayed detonation time of the controlled blasting network (40) includes: The horizontal geometric distance between the central cut hole and the side cut holes, the explosive crack propagation rate of the rock mass, and the time taken for rock block movement are obtained. The initial delay is obtained by dividing the horizontal geometric spacing by the explosion crack propagation rate. The lower limit of the delayed detonation time is obtained by adding the initial delay to the time taken for the rock block to move.

8. The method for step-by-step precise excavation of a deep-buried central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, The controlled blasting network (40) includes a detonation controller, a safety interlocking unit, and a digital electronic detonator. The controlled detonation process includes: The safety interlocking unit collects the blasting time signal at the working face of the main excavation operation system (10); The timing of the detonation signal configured for the central ditch is compared and verified with the blasting time period signal. After the verification is successful, the detonation controller sends a detonation command to the digital electronic detonator arranged in the central rock mass.

9. The method for step-by-step precise excavation of a central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, In the drilling and controlled blasting steps, vibration-damping holes are drilled in the central rock mass at both ends of the two vertical isolation trenches, and the interior of the vibration-damping holes remains unloaded.

10. The method for step-by-step precise excavation of a central drainage ditch in a hard rock tunnel according to claim 1, characterized in that, In the above-mentioned slag removal and system advancement steps, the main slag discharge time window of the main line excavation operation system (10) is obtained; Based on the volume of rock debris from single-cycle blasting in the central water ditch and the rated speed of the cleaning equipment, the time required for rock debris removal is obtained. The cleaning equipment is controlled to synchronously perform the cleaning of rock debris within the time span of the main slag discharge time window.

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