CN113775344A - Tunnel in-situ unilateral extension construction method - Google Patents

Abstract

The invention relates to a tunnel in-situ unilateral extension construction method, which comprises the following process flows: construction preparation; filling a construction platform; supporting by a small advanced catheter; breaking the original lining of the upper step, removing the primary support and expanding and digging; primary support of an upper step; breaking the original lining of the lower step, removing the primary support and expanding and digging; primary support of a lower step; dismantling the original inverted arch; constructing an inverted arch; and (5) waterproof and secondary lining construction. According to the tunnel in-situ unilateral extension construction method, tunnel construction excavation is carried out by adopting a method of advance support for mounting upper and lower steps, so that tunnel excavation circulation is effectively improved, early sealing of primary support and early ring formation are realized; and the displacement and convergence conditions of the surrounding rock by the step method can meet related requirements, so that the construction progress is remarkably accelerated, the disturbance of the surrounding rock is reduced, and the construction safety is improved.

Description

Tunnel in-situ unilateral extension construction method

Technical Field

The invention relates to the technical field of tunnel extension construction, in particular to an in-situ unilateral tunnel extension construction method.

Background

As the requirement of economic development on the transportation capacity of the highway is increasingly improved, at present, many domestic four-lane highways need to be reconstructed and expanded into six lanes or eight lanes, and tunnel expansion becomes an inevitable technical problem of road expansion.

The existing tunnel extension mainly adopts a unilateral extension method, and the excavation method mainly adopts a CD method and a CRD method; the methods have the disadvantages of complicated excavation step sequence, small operation space of each sub-bin, large mutual interference, great difficulty in large-scale mechanized operation, high manual demand, slow construction progress and high engineering measure cost; the closing and looping of the tunnel is slow, and construction of reconstruction and expansion of the tunnel is restricted.

Disclosure of Invention

The invention aims to provide a tunnel in-situ unilateral extension construction method, which aims to solve the problems that the tunnel extension excavation step proposed in the background technology is complicated, the operation space of each sub-bin is small, the mutual interference is large, the large-scale mechanized operation is not facilitated, the manual demand is high, the construction progress is slow, and the engineering measure cost is high; the tunnel sealing and ring forming are slow, so that the construction problem of tunnel reconstruction and expansion is limited.

In order to achieve the purpose, the invention provides the following technical scheme: the tunnel in-situ unilateral extension construction method comprises the following process flows: construction preparation; filling a construction platform; supporting by a small advanced catheter; breaking the original lining of the upper step, removing the primary support and expanding and digging; primary support of an upper step; breaking the original lining of the lower step, removing the primary support and expanding and digging; primary support of a lower step; dismantling the original inverted arch; constructing an inverted arch; and (5) waterproof and secondary lining construction.

Preferably, in the construction preparation step, the existing tunnel and its surroundings are checked to know and grasp the site situation and the construction conditions.

Preferably, in the construction platform filling step, the hole slag is used for filling an upper step construction platform on the road surface of the existing tunnel, and the filling height is 5 m.

Preferably, in the advanced small guide pipe supporting step, contour lines are excavated along the longitudinal direction of the tunnel, holes are drilled outwards at an external insertion angle of 8-12 degrees, the small guide pipes are driven into a rock body and penetrate through the belly of the steel arch frame, the tail parts of the small guide pipes are welded with the steel arch frame, the annular spacing of the small guide pipes is 50cm, the longitudinal spacing is 3m, 1 ring is constructed, the lap joint is larger than or equal to 1m, an orifice end socket and an orifice valve are installed after the small guide pipes are drilled and installed, and then grouting is conducted from bottom to top.

Preferably, in the steps of original lining demolition, primary support demolition and expanding excavation of the upper step, the existing secondary lining demolition of the tunnel adopts a mode of combining loose blasting and mechanical demolition, and the annular demolition sequence is to demolish the upper part of the arch ring first and then symmetrically demolish the structures on two sides.

Preferably, the upper step primary support comprises primary spraying concrete, anchor rod construction, hanging of a steel mesh, arch frame erection and secondary spraying concrete construction.

Preferably, the original lining removing, primary support removing and expanding excavation steps of the lower step are carried out when the upper step is advanced by about 5m, the lower step is excavated, a tunnel slag construction platform is firstly removed, and a layered weak blasting and mechanical crushing mode is adopted to remove the secondary lining of the lower step, the tunnel pavement and the inverted arch filling layer.

Preferably, the lower step primary support step completes primary concrete spraying, anchor rod construction, steel mesh hanging, arch frame erecting and repeated concrete spraying according to the upper step primary support construction procedure.

Preferably, in the steps of original inverted arch demolition and inverted arch construction, the original inverted arch demolition is constructed by adopting large machinery, and the inverted arch construction comprises inverted arch excavation; primary inverted arch supporting, lining and filling; installing inverted arch lining reinforcing steel bars; and (5) constructing inverted arch secondary lining concrete by using the vertical formwork.

Preferably, after the excavation step is completed, a section laser scanner is used for scanning and collecting section information, monitoring sections are arranged at intervals of 10 meters behind the extension tunnel, and sensors are arranged at 3 positions of the arch crown and the arch waist of each section.

Compared with the prior art, the invention has the beneficial effects that: according to the tunnel in-situ unilateral extension construction method, tunnel construction excavation is carried out by adopting a method of advance support for mounting upper and lower steps, so that tunnel excavation circulation is effectively improved, early sealing of primary support and early ring formation are realized; and the displacement and convergence conditions of the surrounding rock by the step method can meet related requirements, so that the construction progress is remarkably accelerated, the disturbance of the surrounding rock is reduced, and the construction safety is improved. According to the tunnel in-situ single-side extension construction method, the broken tunnel door and the lining slag backfill are used as the tunnel upper step excavation construction platform, so that the transportation cost is saved; during the circulating footage construction, the hole slag generated by breaking the tunnel is filled forwards, so that the slag removal engineering quantity is reduced, and the construction speed is improved; the tunnel in-situ expanding excavation is carried out by adopting an upper step and a lower step method, so that the temporary support construction steps are reduced, the primary support ring forming speed is improved, and the surrounding rock disturbance is reduced; the safety of tunnel expanding excavation construction is improved; the upper step construction platform plays a role in back-pressing the bottom of the tunnel; the integral stability of surrounding rock of an excavation section is improved when the existing tunnel lining is broken and the vault is subjected to unilateral expansion excavation; the secondary lining concrete of the existing tunnel is broken by combining loose blasting with machinery, so that the disturbance of blasting on surrounding rocks is effectively reduced, and the construction speed of breaking the secondary lining concrete is improved; acquiring and analyzing section change data in the expansion process by using a tunnel three-dimensional laser section scanner, automatically and intelligently analyzing the over-excavation, under-excavation and guniting consumption, and strictly controlling the field construction quality; an intelligent safety guarantee system is established by using a sensor arrangement technology and a laser scanning technology, so that real-time early warning of surrounding rock breakage and large surrounding rock deformation can be realized, and the tunnel construction safety is effectively improved; the method is suitable for the in-situ unilateral extension of the bidirectional four-lane tunnel of the expressway into bidirectional six-lane middle-long level surrounding rock III and IV level surrounding rock and short-lane III, IV and V level surrounding rock extension excavation construction.

Drawings

FIG. 1 is a process flow diagram of the tunnel in-situ single-side extension construction method of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, the present invention provides a technical solution: the tunnel in-situ unilateral extension construction method comprises the following process flows: construction preparation; filling a construction platform; supporting by a small advanced catheter; breaking the original lining of the upper step, removing the primary support and expanding and digging; primary support of an upper step; breaking the original lining of the lower step, removing the primary support and expanding and digging; primary support of a lower step; dismantling the original inverted arch; constructing an inverted arch; and (5) waterproof and secondary lining construction.

In the construction preparation step, existing tunnels and their peripheries are checked, and site conditions and construction conditions are known and grasped. The verification content of the step comprises the following steps: the method comprises the steps of designing a design drawing of an existing tunnel, relevant geological data of a construction stage, construction conditions, design changes, tunnel portals, tunnel drainage facilities and drainage capacity, buildings, pipelines, residents and the like within a tunnel construction influence range, identifying disease parts such as collapse, water burst and the like during existing tunnel construction according to the construction data, properly controlling footage, properly reducing the explosive blasting amount, and fully protecting rock masses of the disease parts.

In the step of filling the construction platform, the hole slag is used for filling the upper step construction platform on the road surface of the existing tunnel, and the filling height is 5 m. After the construction platform is filled, the construction platform is compacted and leveled by machinery, the excavation rack is guaranteed to be placed stably, and the height of the construction platform can be properly adjusted according to the actual situation on site.

In the step of advancing the support of the small guide pipes, contour lines are excavated along the longitudinal direction of the tunnel, holes are drilled outwards at an external insertion angle of 8-12 degrees, the small guide pipes are driven into a rock body and penetrate through the belly of the steel arch frame, the tail of the steel arch frame is welded with the steel arch frame, the annular distance of the small guide pipes is 50cm, 1 ring is applied at the longitudinal distance of 3m, the lap joint is larger than or equal to 1m, an orifice end socket and an orifice valve are installed after the small guide pipes are drilled and installed, and then grouting is performed from bottom to top.

In the steps of original lining demolition, primary support demolition and expanding excavation of the upper step, the existing secondary lining demolition of the tunnel adopts a mode of combining loosening blasting and mechanical demolition, and the annular demolition sequence is to demolish the upper part of the arch ring first and then symmetrically demolish the structures on two sides. The step is to carry out blast hole drilling construction of the existing tunnel secondary lining concrete arch ring according to the loose blasting design, and the distance of each cycle of drilling is 1-2 steel arch frame distances. The blastholes are arranged at intervals of 50 multiplied by 50cm in a quincunx shape, the blastholes at the arch springing positions are encrypted and arranged at intervals of 40cm, and the blastholes are properly offset when meeting the reinforcing steel bars of the original structure. And after the drilling construction is finished and the inspection is qualified, charging. And (4) before blasting, hoisting the excavation rack out of the blasting area, and carrying out inspection and warning work before blasting. And after blasting is finished, timely smoke discharging, toxin removing, dust settling, post-blasting inspection and dangerous rock cleaning are carried out. After loosening blasting, a hydraulic hammer excavator is adopted to remove the damaged original secondary lining concrete and peripheral loose bodies; after the original secondary lining of the upper step is gradually broken, manually cutting off the secondary lining reinforcing steel bars by using an excavation rack. And a special person commanding machine is arranged in the dismantling process to avoid personal and mechanical injuries, the dismantled steel bars are independently stacked and transported out of the hole, and the damaged concrete is filled forwards by the machine. The primary lining concrete is broken by adopting an excavator hydraulic hammer from the arch crown to the arch waists at two sides step by step. In the process of removing the sprayed concrete, the steel bar net piece and the profile steel arch are gradually removed through mechanical cooperation and manual work, the steel bars of the arch are removed and uniformly stacked, and finally the steel bars are cleaned out of the hole. During the cutting construction of secondary lining and primary support reinforcing steel bars and arch frames, the line arrangement of a cutting machine and the placement of gas bottles are required. And determining an actual excavation profile according to the designed excavation profile and the surrounding rock deformation. And (4) utilizing the existing free surface, and adopting an excavator hydraulic hammer to dig the contour line layer by layer from top to bottom in sequence. After the dangerous stones are expanded to the contour lines, dangerous stones are removed in a mode of combining mechanical operation and manual operation; and when the rock surface is exposed by water seepage, drainage treatment is carried out.

The upper step primary support comprises primary concrete spraying, anchor rod construction, steel bar net piece hanging, arch frame erecting and secondary concrete spraying. In the step, after the expanding excavation is finished, a wet spraying manipulator is adopted to carry out primary spraying concrete construction and the expanding excavation section face is closed. The concrete spraying operation is performed in a subsection and subsection mode in sequence, and the spraying sequence is performed from bottom to top. When the first layer is sprayed with concrete, the concrete is filled and filled completely, and the small pits are sprayed circularly and smoothly. And (3) carrying out mould-hanging concrete spraying treatment on the anchor rod at a serious depression on the rock surface. According to design position mark cavity slip casting stock position, the stock construction order is: drilling in place with a drilling machine → cleaning the hole with high pressure wind → installing an anchor rod → installing a grout stop plug → grouting → installing a backing plate and a nut. The drilling direction and angle are strictly controlled, the hole position allowable deviation is +/-15 mm, the hole depth is not less than the effective length of the anchor rod body, and the hole depth allowable deviation is +/-50 mm. And grouting construction is carried out after the installation is finished, and grouting can be stopped after the air outlet discharges slurry, so that full slurry and grouting quality are ensured. The backing plate is brought into close contact with the sprayed concrete surface. And then the reinforcing mesh and the anchor rod are welded firmly, so that the gap between the reinforcing mesh and the surface of the primary sprayed concrete is controlled to be 20-30 mm. Positioning measurement and arch center installation are carried out. Before installing the arch springing, removing the deficiency slag under the backing plate, and arranging a locking anchor rod at the arch springing; and (5) checking whether the steel frame is vertical or not by using a hanging hammer line in the vertical direction, and correcting. During installation, the steel frames are longitudinally welded and connected by the threaded steel bars, so that the steel frames form a combined supporting system together. The steel frame is attached to the closed concrete. The wet spraying manipulator is adopted for concrete re-spraying, firstly, concrete is sprayed to fill and compact the gap between the steel frame and the primarily sprayed concrete, so that the steel frame and the sprayed concrete form a whole; and then symmetrically spraying upwards from arch springs at two sides, completely covering the steel frame and spraying to the designed thickness, and simultaneously ensuring that the thickness of the sprayed concrete protective layer is not less than 20 mm.

And the steps of breaking and removing the original lining of the lower step, removing the primary support and expanding and digging are carried out when the upper step advances by about 5m, the construction platform of the hole slag is firstly removed by excavating the lower step, and the secondary lining of the lower step, the tunnel pavement and the inverted arch filling layer are removed by adopting a mode of combining layered weak blasting with mechanical crushing. The step dismantling and expanding excavation process is basically the same as that of the upper step. The lower bench construction is divided into left and right side construction, the side lower bench construction is firstly carried out, and then the other side bench construction is carried out. And the other side construction can be carried out after the primary support construction is finished at the expanding and digging side.

And the lower step primary support step completes primary spray concrete, anchor rod construction, steel bar net piece hanging, arch frame erecting and repeated spray concrete construction according to the upper step primary support construction procedure. The step mainly controls the connection of the lower-step primary support steel arch and the upper-step steel arch, and the bolts must be screwed down on the joint plates to ensure the quality of the steel frame installation; and (4) clearing away floating slag at the bottom foot, adding a concrete cushion block at the super-digging position, and applying a foot locking anchor rod.

In the steps of original inverted arch demolition and inverted arch construction, the original inverted arch demolition is constructed by large machinery, and the inverted arch construction comprises inverted arch excavation; primary inverted arch supporting, lining and filling; installing inverted arch lining reinforcing steel bars; and (5) constructing inverted arch secondary lining concrete by using the vertical formwork. After the construction of the left lower step and the right lower step is finished, the inverted arch trestle is erected to carry out inverted arch excavation construction. The original inverted arch is broken and constructed by adopting large machinery; the construction method depends on a project that a bucket-mountain DX420 excavator is matched with a high-power hydraulic hammer to carry out breaking construction. Because the original inverted arch steel bars are dense, the operation space is small, and the drilling and blasting construction is not facilitated, the original inverted arch is broken by mechanical breaking. The excavation length of the soil and soft rock inverted arch is not more than 3m, and the hard rock should not be more than 5 m. After the original inverted arch concrete is crushed, manually cutting off inverted arch reinforcing steel bars, and carrying out classified deslagging. And (5) manually matching with a machine to dig to the designed inverted arch base. And (5) cleaning scum at the bottom of the inverted arch and checking whether overbreak exists or not. And a small amount of underdug parts are chiseled manually, and the overdug parts are filled with concrete of the same grade. The primary support, lining and filling of the inverted arch must be poured once, and the inverted arch must not be poured in different frames. And (3) carrying out primary spraying leveling on the bottom of the inverted arch by adopting a wet spraying manipulator, wherein the primary spraying thickness is not less than 4 cm. After measurement and positioning, the inverted arch centering is installed, the inverted arch centering connecting plate and the lower step centering connecting plate are connected according to design and standard requirements, and then the concrete is re-sprayed. And (5) installing the inverted arch lining reinforcing steel bars after the inverted arch primary support is completed. The binding of the inverted arch second lining reinforcing steel bars ensures that the layer distance of the double-layer reinforcing steel bars and the distance of each layer of reinforcing steel bars meet the requirements, and the positioning of the layer distance can be determined by welding the limiting reinforcing steel bars. Constructing the inverted arch secondary lining concrete by using a vertical mold, and manually installing an inverted arch end template and an arc-shaped steel template in cooperation with machinery; the end template uses a combined arc-shaped steel template, a longitudinal I-shaped steel is used as a bracket for fixing the template, and the combined arc-shaped steel templates are connected and spliced into an integral structure through bolts. The upward supplied concrete is pumped into the mold by a delivery pump, and the inserted vibrator is tamped tightly. And (4) filling the inverted arch after the inverted arch construction is finished, and forbidding the mixed construction of the inverted arch and filling.

And after the excavation step is finished, scanning by using a section laser scanner to collect section information, arranging monitoring sections at intervals of 10 meters behind the extension tunnel, and arranging sensors at 3 positions of the vault and the arch waist of each section. In the step, after the section laser scanner scans, the section information is subjected to over-excavation and under-excavation analysis, and after the initial support is completed, the scanning and data acquisition are carried out to analyze the amount of the primary sprayed concrete guniting. And controlling the tunnel excavation and primary support quality by using the analysis data. And (3) scanning and monitoring for 1-2 times every day within 1-15 days, and establishing an intelligent surrounding rock deformation early warning system. During construction of the hollow anchor rod, sensors are arranged in the drill holes, surrounding rock micro-fracture signals are collected in real time, the geological disaster inoculation process of the front and rear of the working face in the tunnel in-situ expanding and excavating process is monitored in real time, and real-time early warning is carried out.

And during the waterproof board construction, the longitudinal ring is arranged on the drain pipe, the non-woven fabric and the waterproof board according to the design drawing requirements. The waterproof boards are constructed in advance by 9-20m in secondary lining, are laid by a waterproof board laying trolley from bottom to top in an annular mode, are fixedly installed by infrared positioning and hot-melt gaskets, and are welded between the waterproof boards in the annular mode by a heat seal welding machine.

In the secondary lining concrete construction, secondary lining construction is started after primary support deformation is stable. The second lining concrete is integrally cast by adopting a full-section lining template trolley, a concrete delivery pump is adopted for feeding into a mould, and an inserted type tamper is matched with an attached type tamper for tamping; the concrete is poured symmetrically from two sides to the vault from bottom to top in a layered mode with left and right alternate modes, and the left and right height difference is not larger than 1.5 m. And (5) preparing a curing spray pipe for concrete spraying curing.

Main materials and equipment for tunnel in-situ single-side expanding excavation construction are shown in the following table.

Description of the drawings: the material equipment of the standard is the minimum condition of 1 tunnel construction surface.

And (3) quality control:

1. the ISO9000 quality management system is strictly implemented and complies with the relevant regulations of technical Specifications for road and tunnel construction (JTG/T3660) and standards for quality inspection and assessment of road engineering (JTG F80/1).

2. Before construction, detailed construction technology bottom-crossing work is well done; and during construction, the poplar is carried out according to a formulated construction scheme, and the operation key points of each construction flow are strictly installed.

3. Determining a tunnel excavation profile according to the designed excavation profile and the surrounding rock deformation, and strictly controlling underexcavation and overexcavation; and (5) performing ultra excavation and backfilling to be dense.

4. And analyzing data such as over-excavation, under-excavation and guniting consumption of the section in the extension process by using a tunnel section laser scanner, and guiding construction.

5. And combining the thickness condition of the two linings of the existing tunnel, performing special blasting design, and strictly performing the blasting design.

6. The materials used for the tunnel forepoling, the primary shoring and the secondary lining must meet the design requirements and the current national standard.

7. The construction quality of the sprayed concrete and the secondary lining concrete is strictly controlled.

8. And (3) strictly executing a 'three-inspection' system, and entering the next procedure for construction if the acceptance is qualified after each procedure is finished.

9. And establishing a special quality management group to implement a quality responsibility system.

And (4) safety measures are as follows:

1. strictly executing a company ' three-standard integration ' management system, establishing a safety management organization, evaluating and analyzing risk source factors, making a safety management scheme, and executing according to relevant regulations such as ' road engineering construction safety technical specification ' (JTG F90) ' and ' construction site temporary electricity utilization safety technical specification ' (JTJ 46).

2. Before construction, safety technology is well done to meet the end, a safety management leader group is established, and a safety production responsibility system is implemented.

3. Compiling a special safety guarantee measure scheme and a production safety accident emergency plan.

4. The operators for special operations must be certified on duty, attend pre-duty training and strictly comply with safe operating regulations.

5. All personnel entering the construction site must properly wear safety protection equipment as prescribed.

6. And arranging escape system facilities in the tunnel, storing emergency rescue goods and materials and the like.

And (3) environmental protection measures:

1. the three-standard integrated management system is strictly implemented and complies with the relevant regulations of the construction project construction site management regulations.

2. The method strengthens civilized construction and safety awareness of constructors, organizes and learns safety production management regulations and knowledge related to civilized construction, performs post education, explains professional morality and tree industry fresh air.

3. The method carries out the guideline of unifying economic effect and environmental benefit, strives to minimize the adverse effect of engineering construction on the natural and social environment along the line, achieves the coordinated development of the engineering construction and the environmental protection, and ensures the sustainable development of the engineering construction.

And (3) benefit analysis:

1. the technical benefits are as follows: the tunnel in-situ single-side extension construction method solves the problems that the tunnel extension and excavation procedures of a CD method and a CRD method are complicated, the operation space of each warehouse is small, the mutual interference is large, the extension cannot use large-scale mechanical equipment, the ring formation of the closed tunnel is slow, and the construction progress is slow by adopting an upper step and a lower step excavation method; by utilizing a section laser scanning technology and a rock burst sensor monitoring technology, the tunnel expanding excavation and primary support construction quality and the tunnel construction safety are effectively improved.

2. Economic benefits are as follows: the construction method adopts the upper and lower step expanding excavation construction, has simple construction procedures, can input large-scale mechanical equipment without separate operation, reduces the manual demand, and can realize the rapid sealing and ring formation of the tunnel support. The excavation hole slag is used for filling the construction platform, so that the slag discharge operation is reduced, and the excavation circulation of the upper bench is effectively improved; the secondary lining of the existing tunnel is removed by using loose blasting and matching machinery, and the construction efficiency is high. The laser scanning technology effectively controls the tunnel expanding excavation quality and the amount of sprayed concrete, and is beneficial to controlling the construction cost; has good economic benefit.

3. Social benefits are as follows: the construction method realizes mechanical, digital, rapid and safe construction of unilateral in-situ extension of the tunnel. Through the cooperation of various processes, the tunnel is quickly expanded and excavated and quickly sealed to form a ring, so that the safety, the quality and the progress of tunnel construction are ensured; the method is fully determined and approved by construction units and supervision units. The tunnel reconstruction and expansion process is continuously improved and innovated, a good company image is established, and remarkable social benefits are obtained. And precious construction experience is accumulated for the tunnel reconstruction and extension project.

Application example:

1. the construction and extension of a hundred-light tunnel from Guangxi Hezhou to Bama expressway (Duan to Bama section): the construction method is adopted in the engineering of reconstruction and extension of the hundred-light tunnel of the Kwangsi Hezhou-Bama expressway (Duan-Bama section), and the length of the right hole of the hundred-light tunnel is 217 meters, and the length of the left hole of the hundred-light tunnel is 220 meters. The method for expanding excavation by adopting the advance support upper and lower steps can complete 2 excavation cycle constructions every day, the construction progress is fast, the lower step and the inverted arch are constructed closely, and the rapid sealing and ring formation of the tunnel are realized; monitoring and measuring results show that the displacement and convergence of the surrounding rock can meet requirements, and the reliability of the bench method excavation is verified. The construction quality of expanding excavation and concrete spraying is effectively controlled by utilizing a laser scanning technology; the intelligent safety guarantee system monitors and detects the whole tunnel construction process, and ensures the safe and smooth construction of the all-weather tunnel.

2. Guangxi Hao Zhou to Bama expressway (Du an to Bama segment) Tingxin tunnel reconstruction and extension: the construction method is adopted for the IV-level surrounding rock section in the reconstruction and extension engineering of the Gangxi Hezhou to Bama expressway (Duan to Bama section), wherein the length of a right hole is 200 meters, and the length of a left hole is 200 meters. The construction disturbance of the existing two-lining is small and the progress is fast by adopting the loose blasting and matching machinery; demolishing and expanding excavation slag to fill the excavation platform forward rapidly, reduce the upper bench volume of slagging-off, realize the circulation of quick excavation. The laser scanning technology effectively controls the construction quality of tunnel expanding excavation and concrete spraying. According to the construction method, the tunnel is expanded and excavated, the construction progress is fast, the tunnel is sealed to form a ring fast, and the safety of tunnel construction is effectively improved.

The working principle is as follows: when the tunnel in-situ unilateral extension construction method is used, firstly, the basic principle of the bidirectional four-lane tunnel in-situ unilateral extension into the bidirectional six-lane tunnel is that tunnel hole slag is filled into a construction platform, and an up-down step excavation method is adopted for carrying out extension excavation construction. And (4) carrying out the advanced small conduit support of the upper step, the original tunnel lining of the upper step, the primary support breaking and the expanding excavation construction on the platform. The original tunnel lining is demolished by adopting loose blasting and mechanical demolition; mechanical excavation is adopted for tunnel expanding excavation; the original tunnel inverted arch is dismantled by a high-power machine. A section laser scanner is arranged in the tunnel to collect section data, the over-excavation, under-excavation and guniting consumption is analyzed, and the site construction quality is controlled. And (3) a sensor is arranged in the drilled hole to collect a surrounding rock micro-fracture signal, and a surrounding rock safety early warning system is established, so that a series of work is completed.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.

Claims (10)

1. The tunnel in-situ unilateral extension construction method is characterized by comprising the following steps: the tunnel in-situ single-side extension construction method comprises the following process flows: construction preparation; filling a construction platform; supporting by a small advanced catheter; breaking the original lining of the upper step, removing the primary support and expanding and digging; primary support of an upper step; breaking the original lining of the lower step, removing the primary support and expanding and digging; primary support of a lower step; dismantling the original inverted arch; constructing an inverted arch; and (5) waterproof and secondary lining construction.

2. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: in the construction preparation step, existing tunnels and the peripheries thereof are checked, and site conditions and construction conditions are known and mastered.

3. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: in the construction platform filling step, the hole slag is used for filling an upper step construction platform on the road surface of the existing tunnel, and the filling height is 5 m.

4. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: in the advanced small guide pipe supporting step, contour lines are excavated along the longitudinal direction of a tunnel, holes are drilled outwards at an external insertion angle of 8-12 degrees, small guide pipes are driven into a rock body and penetrate through the belly of a steel arch frame, the tail of each small guide pipe is welded with the steel arch frame, the circumferential distance of the small guide pipes is 50cm, the longitudinal distance of the small guide pipes is 3m, 1 ring is constructed, the lap joint is larger than or equal to 1m, an orifice end socket and an orifice valve are installed after the small guide pipes are drilled and installed, and then grouting is conducted from bottom to top.

5. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: in the steps of original lining demolition, primary support demolition and expanding excavation of the upper step, the existing secondary lining demolition of the tunnel adopts a mode of combining loosening blasting and mechanical demolition, and the annular demolition sequence is to demolish the upper part of the arch ring first and then symmetrically demolish the structures on two sides.

6. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: the upper step primary support comprises primary spraying concrete, anchor rod construction, hanging of a steel mesh sheet, arch frame erection and secondary spraying concrete construction.

7. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: and the steps of breaking and removing the original lining of the lower step, removing the primary support and expanding and digging are carried out when the upper step is advanced by about 5m, the lower step is excavated, firstly, a tunnel slag construction platform is removed, and a secondary lining of the lower step, a tunnel pavement and an inverted arch filling layer are removed by adopting a mode of combining layered weak blasting with mechanical crushing.

8. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: and the lower step primary support step completes primary spray concrete, anchor rod construction, steel bar net piece hanging, arch frame erecting and repeated spray concrete construction according to the upper step primary support construction procedure.

9. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: in the steps of original inverted arch demolition and inverted arch construction, the original inverted arch demolition is constructed by large machinery, and the inverted arch construction comprises inverted arch excavation; primary inverted arch supporting, lining and filling; installing inverted arch lining reinforcing steel bars; and (5) constructing inverted arch secondary lining concrete by using the vertical formwork.

10. The tunnel in-situ single-side extension construction method according to claim 1, characterized in that: and after the excavation step is finished, scanning by using a section laser scanner to collect section information, arranging monitoring sections at the rear of the extension tunnel at intervals of 10 meters, and arranging sensors at 3 positions of the arch crown and the arch waist on each section.

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