Small pilot tunnel entering construction method for auxiliary channel of highway tunnel

Abstract

The invention provides a highway tunnel auxiliary channel small pilot tunnel entering construction method, and belongs to the technical field of entering construction, and the method comprises the following steps: step 1, preparing before construction, carrying out geological exploration and risk assessment, excavating a small pilot tunnel, determining the position of the small pilot tunnel, excavating the small pilot tunnel, carrying out advance support and primary support, and expanding excavation to a designed section; step-by-step expanding excavation and segmented expanding excavation are conducted, final supporting is conducted, after expanding excavation is conducted to a designed section, final supporting work is conducted, concrete lining is poured, safety and stability of a tunnel structure are guaranteed, monitoring and adjusting are conducted, the water level and surrounding rock deformation are monitored in real time, and measures are adjusted in time. The small-section construction can be more refined, the engineering quality can be improved, and in the small pilot tunnel construction process, surrounding rock deformation and water level change can be monitored in real time, construction measures can be adjusted in time, and the engineering quality is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel entry construction, and in particular to a tunnel entry construction method for a small guide tunnel in an auxiliary channel of a highway tunnel. Background Art

[0002] The national medium- and long-term development plan places transportation infrastructure construction in an important position. The focus of major infrastructure construction is gradually moving towards areas with extremely complex terrain and geology. Large-section highway tunnel projects with a two-way six-lane area of ​​10,000 meters are being or will be put into production soon. Inclined shafts are one of the main ways to speed up the construction progress as auxiliary construction channels for long and large tunnels. The intersection of the inclined shaft and the main tunnel has a large section and complex structural stress, which is the key control section for tunnel construction safety and quality. Therefore, it is necessary to design a construction method for small pilot tunnels in auxiliary channels of highway tunnels. Summary of the invention

[0003] The purpose of the present invention is to provide a construction method for a small guide tunnel for an auxiliary channel of a highway tunnel, so as to solve the technical problems raised in the background technology.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A method for constructing a small pilot tunnel for an auxiliary channel of a highway tunnel, the method comprising the following steps:

[0006] Step 1: Pre-construction preparation, geological survey and risk assessment;

[0007] Step 2: excavation of small pilot tunnel, determination of the location of the small pilot tunnel, and excavation of the small pilot tunnel;

[0008] Step 3: Carry out advance support and initial support;

[0009] Step 4: Excavate to the designed section, gradually and segmentally;

[0010] Step 5: Final support: After the tunnel is excavated to the designed section, the final support work is carried out and the concrete lining is poured to ensure the safety and stability of the tunnel structure;

[0011] Step 6: Monitoring and adjustment: monitor the water level and surrounding rock deformation in real time and adjust measures in time.

[0012] Furthermore, in step 1, ground survey: the topography and geological structure of the construction area are understood through the data of topographic maps, remote sensing images and geological maps; drilling sampling: drilling is carried out on site to collect core samples and analyze the rock type, strength and degree of fragmentation; geophysical exploration: the information of underground structure is obtained by using geophysical exploration methods, seismic wave detection or electromagnetic detection; groundwater investigation and hydrogeological testing: the distribution, flow direction and water pressure of groundwater are determined by drilling pumping test or permeability coefficient determination method; dynamic observation of groundwater: long-term observation wells are set up to monitor the changes of groundwater level and provide a basis for drainage design during construction; surrounding rock stability evaluation: rock mass classification is determined: surrounding rock is classified according to rock mass quality index and rock mass integrity index; stability calculation: rock mass mechanics theory and numerical simulation software are used to predict the stability of surrounding rock under different working conditions.

[0013] Furthermore, in step 2, a location suitable for excavating a small pilot tunnel is selected, such as a location with good geological conditions or low construction difficulty. The optimal location is selected, and a small-section excavation method is adopted, which is sufficient for construction personnel and equipment to pass through. The cross-sectional dimensions of the small pilot tunnel may be 5 meters in bottom width and 4.89 meters in height.

[0014] Furthermore, in step 3, before or during the excavation of the small pilot tunnel, in order to reduce the disturbance of the excavation to the surrounding rock and ensure the safety of construction, steel pipes or a scaffolding structure composed of steel pipes are pre-driven into the loose and broken strata before tunnel excavation to enhance the stability of the surrounding rock, and grouting reinforcement is performed to form a temporary support structure.

[0015] Furthermore, in step 3, initial support is carried out immediately after excavation, including shotcrete, anchor rods and steel mesh to prevent the surrounding rock from becoming unstable. The shotcrete thickness is 5 cm, and φ8 steel mesh and Ф22 mortar anchor rod materials are used.

[0016] Furthermore, in step 4, the order of excavation is determined according to geological conditions and design requirements. One side is excavated first, and then the other side is excavated after it is stable. The excavation process is divided into three stages. Each stage excavates a fixed length and width. The first stage excavates to a fixed size, the second stage further excavates, and the third stage finally reaches the designed section.

[0017] By gradually expanding the excavation method, the small guide tunnel can be gradually expanded to the designed section while ensuring safety, thereby achieving smooth construction of the tunnel intersection, effectively reducing construction risks, and improving project quality and efficiency.

[0018] Further, in step 5, the base surface is cleaned: the surface of the surrounding rock after the expansion is cleaned to ensure that there are no debris and loose rocks; the template is installed: the template is installed according to the design drawings to ensure that the template position is accurate and stable; the steel bar is tied: the steel bar is tied according to the design requirements to ensure that the steel bar is arranged correctly and the spacing is uniform; the embedded parts are installed: the embedded parts, including expansion joints and drainage pipes, are installed;

[0019] Concrete mixing: Mix concrete according to the designed mix ratio to ensure that all performance indicators of the concrete meet the requirements; Pouring order: Pour from the bottom upwards to ensure that the concrete densely fills the space inside the formwork; Vibration: Use a vibrating rod to vibrate to ensure that the concrete is dense and free of bubbles; Pouring speed: Control the pouring speed to avoid concrete segregation caused by too fast pouring.

[0020] Further, in step 6, water level monitoring, installation of water level monitoring equipment, water level gauges or pressure sensors for real-time monitoring of groundwater levels; monitoring point layout: reasonable arrangement of monitoring points around the tunnel and in the construction area to ensure that the monitoring network covers the entire construction area; data collection: regular or real-time collection of water level data, recording and analyzing water level change trends; early warning system: establishment of an abnormal water level early warning system, automatic alarm when the water level exceeds the preset threshold; emergency measures: once the water level is found to rise abnormally, the emergency plan is immediately activated, drainage measures are taken, additional drainage pumps are installed or drainage capacity is increased;

[0021] Surrounding rock deformation monitoring: use surrounding rock deformation monitoring instruments, convergence meters or displacement sensors to monitor the deformation of surrounding rocks in real time; monitoring point layout: arrange monitoring points at key locations of surrounding rocks, especially in areas with unstable surrounding rocks or complex geological conditions; data collection: collect surrounding rock deformation data regularly or in real time, record and analyze deformation conditions; data analysis: analyze the collected data, identify deformation patterns and development trends, and evaluate surrounding rock stability; early warning system: establish an abnormal surrounding rock deformation early warning system, which automatically alarms when the deformation exceeds the preset threshold; emergency measures: once abnormal surrounding rock deformation is found, immediately activate the emergency plan, take reinforcement measures, and add anchors or spray concrete;

[0022] By real-time monitoring of water levels and surrounding rock deformation and timely adjustment of construction measures, various risks in the construction process can be effectively prevented and controlled to ensure the safety of tunnel construction and project quality.

[0023] The present invention has the following beneficial effects due to the adoption of the above technical solution:

[0024] The construction of the small section of the present invention can be more refined, which is conducive to improving the quality of the project. During the construction of the small pilot tunnel, the deformation of the surrounding rock and the change of the water level can be monitored in real time, and the construction measures can be adjusted in time to ensure the quality of the project. It is suitable for areas with complex geological conditions and poor surrounding rock stability. It can effectively reduce construction risks, reduce interference with existing traffic and the surrounding environment, and improve construction efficiency. Through the segmented construction method, parallel operations can be achieved, and the overall construction efficiency can be improved. It has significant advantages in terms of improving construction safety, facilitating construction management, accelerating construction progress, reducing construction costs, and improving project quality. In practical applications, according to the specific engineering characteristics and geological conditions, the construction plan can be flexibly adjusted to give full play to the advantages of small pilot tunnel entry construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are only for the purpose of enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

[0027] like Figure 1 As shown, a construction method for a small pilot tunnel for an auxiliary channel of a highway tunnel comprises the following steps:

[0028] Step 1: Pre-construction preparation, geological survey and risk assessment. Ground survey, through topographic maps, remote sensing images, geological maps, to understand the topography and geological structure of the construction area; Drilling sampling: Drilling on site, collecting core samples, analyzing rock type, strength, and degree of fragmentation; Geophysical exploration: Using geophysical exploration methods, seismic wave detection or electromagnetic detection, to obtain information on underground structures; Groundwater survey, hydrogeological testing: Determine the distribution, flow direction and water pressure of groundwater through drilling pumping tests or permeability coefficient determination methods; Groundwater dynamic observation: Set up long-term observation wells to monitor groundwater level changes and provide a basis for drainage design during construction; Surrounding rock stability evaluation, determine rock mass classification: Classify surrounding rocks according to rock mass quality indicators and rock mass integrity index; Stability calculation: Use rock mass mechanics theory and numerical simulation software to predict the stability of surrounding rocks under different working conditions.

[0029] Step 2: Excavation of small pilot tunnels, determine the location of small pilot tunnels, and excavate small pilot tunnels. Choose a location suitable for excavating small pilot tunnels, choose a place with good geological conditions or low construction difficulty, select the best location, and use a small cross-section excavation method that is sufficient for construction personnel and equipment to pass through. The cross-sectional dimensions of the small pilot tunnel may be 5 meters in width and 4.89 meters in height.

[0030] Step 3: Carry out advance support and initial support. This is carried out before or during the excavation of the small pilot tunnel. In order to reduce the disturbance of the excavation to the surrounding rock and ensure the safety of construction, steel pipes or a scaffolding structure composed of steel pipes are pre-driven into the loose and broken strata before tunnel excavation to enhance the stability of the surrounding rock. Steel pipes or pipe scaffolds are pre-driven and grouting is performed to reinforce them to form a temporary support structure. Initial support is carried out immediately after excavation, including shotcrete, anchor rods and steel mesh to prevent the surrounding rock from becoming unstable. The thickness of the shotcrete is 5 cm, and φ8 steel mesh and Ф22 mortar anchor rod materials are used.

[0031] Step 4: Excavate to the designed section, excavate gradually and in sections. According to geological conditions and design requirements, determine the order of excavation, first excavate one side, and then excavate the other side after it stabilizes. The excavation process is divided into three stages. Each stage excavates a fixed length and width. The first stage excavates to a fixed size, the second stage further excavates, and the third stage finally reaches the designed section.

[0032] By gradually expanding the excavation method, the small guide tunnel can be gradually expanded to the designed section while ensuring safety, thereby achieving smooth construction of the tunnel intersection, effectively reducing construction risks, and improving project quality and efficiency.

[0033] Step 5: Final support. After the excavation reaches the designed section, the final support work is carried out and the concrete lining is poured to ensure the safety and stability of the tunnel structure. Clean the base surface: clean the surrounding rock surface after the excavation to ensure that there are no debris and loose rocks; template installation: install the template according to the design drawings to ensure that the template position is accurate and stable; steel bar binding: bind the steel bars according to the design requirements to ensure that the steel bars are arranged correctly and the spacing is uniform; embedded parts installation: install embedded parts, including expansion joints and drainage pipes;

[0034] Concrete mixing: Mix concrete according to the designed mix ratio to ensure that all performance indicators of the concrete meet the requirements; Pouring order: Pour from the bottom upwards to ensure that the concrete densely fills the space inside the formwork; Vibration: Use a vibrating rod to vibrate to ensure that the concrete is dense and free of bubbles; Pouring speed: Control the pouring speed to avoid concrete segregation caused by too fast pouring.

[0035] Step 6: Monitoring and adjustment, real-time monitoring of water level and surrounding rock deformation, and timely adjustment of measures. Water level monitoring, installation of water level monitoring equipment, water level gauges or pressure sensors, for real-time monitoring of groundwater level; Monitoring point layout: Reasonable arrangement of monitoring points around the tunnel and in the construction area to ensure that the monitoring network covers the entire construction area; Data collection: Regular or real-time collection of water level data, recording and analyzing water level change trends; Early warning system: Establish a water level abnormality early warning system, which automatically alarms when the water level exceeds the preset threshold; Emergency measures: Once the water level is found to be abnormally high, immediately activate the emergency plan, take drainage measures, add drainage pumps or increase drainage capacity.

[0036] Surrounding rock deformation monitoring: use surrounding rock deformation monitoring instruments, convergence meters or displacement sensors to monitor the deformation of the surrounding rock in real time; monitoring point layout: arrange monitoring points at key locations of the surrounding rock, especially in areas with unstable surrounding rock or complex geological conditions; data collection: collect surrounding rock deformation data regularly or in real time, record and analyze deformation conditions; data analysis: analyze the collected data, identify deformation patterns and development trends, and evaluate surrounding rock stability; early warning system: establish an abnormal surrounding rock deformation early warning system, which automatically alarms when the deformation exceeds the preset threshold; emergency measures: once abnormal surrounding rock deformation is found, immediately activate the emergency plan, take reinforcement measures, and add anchors or spray concrete.

[0037] By real-time monitoring of water levels and surrounding rock deformation and timely adjustment of construction measures, various risks in the construction process can be effectively prevented and controlled to ensure the safety of tunnel construction and project quality.

[0038] During construction, monitoring and measurement are strengthened at the main tunnel and intersections. Monitoring and measurement points are arranged at the locations where cross-section changes occur and at intersections. Observation points are buried and readings are taken in time after each excavation. The initial readings are controlled to be taken within 12 hours after excavation.

[0039] After the initial support steel frame of the small pilot tunnel is removed, the initial support of the main tunnel must be immediately applied, and the next cycle of excavation can only be carried out after the sprayed concrete strength reaches the design strength. The reserved settlement of the main tunnel steel arch frame should be appropriately increased within the triangular area, which should be controlled within 10cm to 15cm.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Construction method of small pilot tunnel for auxiliary channel of highway tunnel, Features: The method comprises the following steps: Step 1: Pre-construction preparation, geological survey and risk assessment; Step 2: excavation of small pilot tunnel, determination of the location of the small pilot tunnel, and excavation of the small pilot tunnel; Step 3: Carry out advance support and initial support; Step 4: Excavate to the designed section, gradually and segmentally; Step 5: Final support: After the tunnel is excavated to the designed section, the final support work is carried out by pouring concrete lining to ensure the safety and stability of the tunnel structure. Step 6: Monitoring and adjustment: monitor the water level and surrounding rock deformation in real time and adjust measures in time.

2. The construction method for small pilot tunnels in auxiliary passages of highway tunnels according to claim 1, Features: In step 1, ground survey, through topographic maps, remote sensing images, geological maps, to understand the topography and geological structure of the construction area; drilling sampling: drilling on site, collecting core samples, analyzing rock type, strength, and degree of fragmentation; geophysical exploration: using geophysical exploration methods, seismic wave detection or electromagnetic detection to obtain information on underground structures; groundwater investigation, hydrogeological testing: through drilling pumping test or permeability coefficient measurement method, determine the distribution, flow direction and water pressure of groundwater; groundwater dynamic observation: set up long-term observation wells to monitor groundwater level changes and provide a basis for drainage design during construction; surrounding rock stability evaluation, determine rock mass classification: classify surrounding rocks according to rock mass quality indicators and rock mass integrity index; stability calculation: use rock mechanics theory and numerical simulation software to predict the stability of surrounding rocks under different working conditions.

3. The construction method for small pilot tunnel in auxiliary channel of highway tunnel according to claim 1, Features: In step 2, select a location suitable for excavating a small pilot tunnel, choose a place with good geological conditions or low construction difficulty, select the best location, and adopt a small-section excavation method that is sufficient for construction personnel and equipment to pass through. The cross-sectional dimensions of the small pilot tunnel may be 5 meters in bottom width and 4.89 meters in height.

4. The method for constructing a small pilot tunnel for an auxiliary channel of a highway tunnel according to claim 1, Features: In step 3, it is carried out before or during the excavation of the small pilot tunnel. In order to reduce the disturbance of the excavation to the surrounding rock and ensure the safety of construction, steel pipes or a scaffolding structure composed of steel pipes are pre-driven into the loose and broken strata before tunnel excavation to enhance the stability of the surrounding rock. Steel pipes or pipe scaffolds are pre-driven and grouting is carried out to reinforce them to form a temporary support structure.

5. The construction method for small pilot tunnel in auxiliary channel of highway tunnel according to claim 1, Features: In step 3, initial support is carried out immediately after excavation, including shotcrete, anchor rods and steel mesh to prevent the surrounding rock from becoming unstable. The shotcrete thickness is 5 cm, and φ8 steel mesh and Ф22 mortar anchor rod materials are used.

6. The construction method for small pilot tunnel entry of the auxiliary channel of a highway tunnel according to claim 1, Features: In step 4, the order of excavation is determined according to geological conditions and design requirements. One side is excavated first, and then the other side is excavated after it stabilizes. The excavation process is divided into three stages. Each stage excavates a fixed length and width. The first stage excavates to a fixed size, the second stage further excavates, and the third stage finally reaches the designed section. By gradually expanding the excavation method, the small guide tunnel can be gradually expanded to the designed section while ensuring safety, thereby achieving smooth construction of the tunnel intersection, effectively reducing construction risks, and improving project quality and efficiency.

7. The method for constructing a small pilot tunnel for an auxiliary channel of a highway tunnel according to claim 1, Features: In step 5, clean the base surface: clean the surrounding rock surface after the expansion and excavation to ensure that there are no debris and loose rocks; install the template: install the template according to the design drawings to ensure that the template is accurately positioned and stable; tie the steel bars: tie the steel bars according to the design requirements to ensure that the steel bars are correctly arranged and evenly spaced; install the embedded parts: install the embedded parts, including expansion joints and drainage pipes; Concrete mixing: Mix concrete according to the designed mix ratio to ensure that all performance indicators of the concrete meet the requirements; Pouring order: Pour from the bottom upwards to ensure that the concrete densely fills the space inside the formwork; Vibration: Use a vibrating rod to vibrate to ensure that the concrete is dense and free of bubbles; Pouring speed: Control the pouring speed to avoid concrete segregation caused by too fast pouring.

8. The method for constructing a small pilot tunnel for an auxiliary channel of a highway tunnel according to claim 1, Features: In step 6, water level monitoring: installing water level monitoring equipment, water level gauges or pressure sensors to monitor the groundwater level in real time; monitoring point layout: reasonably arranging monitoring points around the tunnel and in the construction area to ensure that the monitoring network covers the entire construction area; data collection: collecting water level data regularly or in real time, recording and analyzing water level change trends; early warning system: establishing a water level abnormality early warning system, which automatically alarms when the water level exceeds the preset threshold; emergency measures: once the water level is found to rise abnormally, immediately activate the emergency plan, take drainage measures, add drainage pumps or increase drainage capacity; Surrounding rock deformation monitoring: using surrounding rock deformation monitoring instruments, convergence meters or displacement sensors to monitor the deformation of surrounding rocks in real time; monitoring point arrangement: arranging monitoring points at key locations of surrounding rocks, especially in areas with unstable surrounding rocks or complex geological conditions; data collection: collecting surrounding rock deformation data regularly or in real time, recording and analyzing deformation conditions; data analysis: analyzing the collected data, identifying deformation patterns and development trends, and evaluating surrounding rock stability; Early warning system: Establish an abnormal deformation early warning system for surrounding rock, and automatically alarm when the deformation exceeds the preset threshold; Emergency measures: Once abnormal deformation of surrounding rock is found, immediately activate the emergency plan, take reinforcement measures, add anchors or spray concrete; By real-time monitoring of water levels and surrounding rock deformation and timely adjustment of construction measures, various risks in the construction process can be effectively prevented and controlled to ensure the safety of tunnel construction and project quality.

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