Method for blasting construction of newly-built tunnel under existing pipeline

Abstract

The application discloses a blasting construction method for a newly-built tunnel underpassing existing pipelines, real-time monitoring of the existing pipelines, and ensuring the operation safety of the existing pipelines, and provides a theoretical basis for controlling and optimizing blasting parameters; drilling and blasting construction of peripheral holes is performed in a small interval, short footage and low explosive quantity mode, a smooth surface effect is good, and the one-time forming qualification rate of a working face is improved; a wedge-shaped cutting technology is adopted, cutting holes are first detonated, free surfaces are provided for auxiliary holes and peripheral holes, space is provided for rock expansion, blasting efficiency is improved, and single-shot explosive quantity is reduced. A blasting vibration velocity detection system is adopted to perform real-time monitoring on blasting vibration, whether the blasting vibration velocity is over standard is understood, and dynamic protection on the safety and stability of the pipelines in the construction process is ensured. Meanwhile, blasting parameters are adjusted according to feedback data, and the control blasting technology is further optimized.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for blasting construction of a new tunnel under an existing pipeline. Background Technology

[0002] As the scale of underground engineering construction continues to expand, the protection of adjacent buildings, especially existing underground pipelines, becomes more difficult and risky. A natural gas pipeline with a diameter of 1.016 meters runs through the surface above a certain tunnel under construction. Conventional tunnel drilling and blasting methods are insufficient to ensure the structural stability and operational safety of the above-ground gas pipeline. Therefore, the construction design drawings recommend mechanical excavation. However, mechanical excavation of tunnels is slow and cannot meet the contractual schedule.

[0003] Therefore, it is necessary to develop a method for constructing new tunnels under existing pipelines using blasting techniques to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to design a method for blasting construction of new tunnels under existing pipelines in order to solve the above-mentioned problems.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] The blasting construction method for constructing a new tunnel under existing pipelines includes the following steps:

[0007] S1, Drilling and blasting design; including:

[0008] Explosive consumption per unit volume: 0.7 kg / m³ 3 ;

[0009] Cutting method: The upper step cutting holes and the first and second ring auxiliary holes adopt horizontal wedge cutting, and the remaining auxiliary holes adopt straight cutting; the lower step adopts straight cutting, and all the surrounding holes adopt small-spacing, small-angle outward straight cutting.

[0010] Hole Layout: Cut Holes: Hole spacing is 0.4m, hole depth is 2.2m, number of holes is 4, single hole charge is 1.93kg, total charge of 4 holes is 7.72kg; Peripheral Holes: Small spacing and low charge are adopted, hole spacing a = 0.30m, hole depth is 2.0m, hole bottom is inclined outwards from the outline by 2°, number of holes is 120; single hole charge is 0.12kg, plugging length is 0.2m, total charge of 120 holes is 14.4kg; Auxiliary Holes: Hole spacing is 0.7-0.9m, hole depth is 2.0m, number of holes is 162, single hole charge is 0.6-0.8kg, maximum single charge is 18.4kg;

[0011] S2. Charge structure layout: The slotted boreholes and auxiliary boreholes adopt a radially uncoupled continuous charge structure; the peripheral boreholes adopt a radially uncoupled, axially spaced charge structure.

[0012] S3. Safety calculation of blasting vibration; Calculate the blasting vibration values ​​of each protected object at the distance from the blasting point according to Sadovsky's empirical formula:

[0013]

[0014] K – A coefficient related to topography and geology;

[0015] α — Seismic attenuation coefficient;

[0016] Q—Maximum charge for detonation in the same phase;

[0017] Determine whether the blasting vibration velocity in the drilling and blasting design can be controlled within the specified safety allowable range. If so, the blasting design meets the requirements and proceed to the next step.

[0018] S4, Detonation; Detonate in the order of slotted holes, auxiliary holes, and surrounding holes.

[0019] Specifically, the blasting construction method for new tunnels passing under existing pipelines also includes step S5, monitoring blasting vibration velocity; the blasting vibration detection adopts a real-time monitoring method, and three measuring points are set up on the ground of the gas pipeline foundation; through blasting monitoring, the ground mass vibration velocity of key parts of the gas pipeline is obtained, compared with the design value, and the impact of blasting vibration on the gas pipeline is determined.

[0020] Furthermore, blasting detection was conducted by setting up measuring points at the midpoints of the right tunnel, left tunnel, and both left and right tunnels.

[0021] Furthermore, the sensor installation at the measuring point includes;

[0022] The sensor is installed on the test pile or foundation;

[0023] Remove dust and dirt from the surface of the test pile or foundation, and clean the surface with a brush;

[0024] According to the orientation of the three-dimensional rectangular coordinate system, three sensors are arranged on the surface of the natural gas pipeline foundation in the vertical, horizontal tangential and horizontal radial directions; and the installation positions and sensor orientations are marked with a conspicuous marker.

[0025] The horizontal tangential velocity sensor and the horizontal radial velocity sensor should be on the same plane and parallel to the horizontal plane. The horizontal radial velocity sensor should point to the blast center, and the vertical velocity sensor must be arranged perpendicular to the horizontal plane.

[0026] Preferably, the sensor is bonded with plaster. The plaster is mixed with water to form a paste, which is then evenly applied to the bottom surface of the sensor. The thickness of the paste does not exceed 1 cm, and the plaster curing time is not less than 10 minutes, so that the sensor and the surface of the target being measured form a rigid connection.

[0027] Specifically, the blasting construction method for constructing a new tunnel under an existing pipeline also includes step S6: analysis of blasting vibration monitoring data. After the blasting mileage enters the monitoring mileage, real-time monitoring of each blast begins. After on-site testing, the testing personnel import the data into a computer and print out the waveform diagram and test result table, which are then given to the verification personnel. The verification personnel check and verify the test results based on the original data and calculate the coefficients and attenuation index related to the terrain and geology between the blasting point and the surrounding protected buildings based on the verified test data. During the monitoring process, the point with the largest vibration peak is selected as the early warning point for the safety and stability control of the natural gas pipeline. When the peak exceeds the safe allowable vibration velocity of the natural gas pipeline, the blasting operation is immediately stopped, and the blasting parameters are adjusted.

[0028] Specifically, in step S1, a hollow hole is left in the middle of the slot.

[0029] The beneficial effects of this invention are as follows:

[0030] This application integrates the construction characteristics and standards of new tunnels passing under existing pipelines, designing a simpler and more flexible controlled blasting structure. Furthermore, real-time monitoring of existing pipelines ensures their operational safety and provides a theoretical basis for optimizing blasting parameters in controlled blasting. Drilling and blasting operations employ small-interval, short-footprint, and low-charge methods for the peripheral holes, resulting in a smooth surface finish and increased first-pass yield of the tunnel face. A wedge-shaped slotting technique is used, with the slotted holes detonated first, providing free surfaces for auxiliary and peripheral holes, allowing space for rock expansion, improving blasting efficiency, and reducing the charge per blast. A blasting vibration velocity detection system is used to monitor blasting vibration in real time, ensuring dynamic protection of the pipeline's safety and stability during construction. Simultaneously, blasting parameters are adjusted based on feedback data to further optimize controlled blasting technology. Attached Figure Description

[0031] Figure 1 Detailed drawing of the blast hole layout;

[0032] Figure 2 Provide a top view of the blast hole layout;

[0033] Figure 3 This is a schematic diagram of a continuous charge structure;

[0034] Figure 4 This is a schematic diagram of a spaced-charge structure;

[0035] Figure 5 This is a schematic diagram of the monitoring results of blasting vibration velocity.

[0036] In the diagram: 1. Fuse; 2. Clay; 3. Non-electric detonator; 4. Explosive charge; 5. Detonating cord. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0040] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," "outer," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0041] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0042] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, terms such as "set" and "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0044] Blasting methods for constructing new tunnels under existing pipelines include:

[0045] S1, Drilling and blasting design

[0046] 1. Hole diameter D = 42mm;

[0047] 2. Hole depth L = 2.0m;

[0048] 3. Explosive consumption per unit: The value used in this design is 0.7 kg / m³. 3 ;

[0049] 4. Grooving method:

[0050] The upper bench cut holes and the first and second rings of auxiliary holes adopt horizontal wedge cuts, while the remaining auxiliary holes adopt straight cuts. An empty hole is left in the middle of the cut holes to provide a free surface for the cut holes and provide space for rock expansion, so as to improve the blasting effect. The lower bench adopts the straight cut method, and all the surrounding holes adopt the small-spacing, small-angle outward straight cut method.

[0051] 5. Arrangement of blast holes:

[0052] 1) Cut holes: The spacing between the cut holes is 0.4m, and the hole depth is 2.2m. There are 4 cut holes. The charge per hole is 1.93kg, and the total charge of the 4 holes is 7.72kg.

[0053] 2) Peripheral holes: A small-spaced, low-charge method is adopted, with a hole spacing of a = 0.30m, a hole depth of 2.0m, and a hole bottom inclined outward at 2° from the outline. The number of holes is 120. The charge per hole is 0.12kg, the plugging length is 0.2m, and the total charge of 120 holes is 14.4kg.

[0054] 3) Auxiliary holes: The spacing between blast holes is 0.7–0.9 m, the depth of blast holes is 2.0 m, and the number of blast holes is 162. The charge per hole is 0.6–0.8 kg, and the maximum charge per blast is 18.4 kg.

[0055] For details regarding the location, drilling angle, and drilling depth of the blast holes at the working face, please refer to [link / reference]. Figure 1 and Figure 2 .

[0056] 6. Drilling should meet the following requirements:

[0057] The drilling depth, angle, row spacing, and line spacing of the blast holes should conform to Table 1.

[0058] Table 1 Drilling Location Requirements

[0059]

[0060] After the blast holes are drilled, they should be checked one by one against the parameters in the drilling and blasting design and the blast hole layout diagram, and the results should be recorded. If any blast holes are found to be non-compliant, they should be re-drilled. After the drilling is completed, they should be inspected again. After the inspection is passed, the next process can be carried out.

[0061] Before loading explosives, the blast holes must be thoroughly cleaned of mud and stone powder to ensure that there are no foreign objects inside and that the explosives are loaded evenly. All blast holes for loading explosives must be plugged with blasting mud, and the plugging length should not be less than 20cm.

[0062] For details on the charging and blasting parameters of each blast hole on the upper and lower steps, please refer to Tables 2 and 3.

[0063] Table 2 Bench Excavation Method ① Drilling and Blasting Parameters for the Upper Bench

[0064]

[0065] Table 3 Bench Excavation Method ① Drilling and Blasting Parameters for the Upper Bench

[0066]

[0067] S2. Charge structure layout;

[0068] The slotted holes, auxiliary holes, and bottom plate holes adopt a radially decoupled continuous charge structure, such as... Figure 3 As shown. Multiple explosive charges are set without gaps, with the lead wire passing inward through the blast hole to connect to the non-electric detonator, which in turn connects to the explosive charge. Special blast hole mud is used to seal the blast hole.

[0069] The peripheral holes employ a radially decoupled, axially discontinuous charging structure (interval charging structure). Each explosive charge within the hole is connected by detonating cord. Special stemming material is used to plug the boreholes to ensure a smooth blasting effect. The charging structure is as follows: Figure 4 As shown.

[0070] S3, Safety Calculation for Blasting Vibration

[0071] The following table shows the blast vibration values ​​for each protected object at the distance from the blast point, calculated using Sadovsky's empirical formula.

[0072]

[0073] K—a coefficient related to topography and geology. The value is taken according to the lithology, as detailed in Table 4. In this case, it is taken as 350.

[0074] α—Seismic attenuation coefficient, the value of which is determined according to lithology (see Table 4). In this study, it is taken as 1.5.

[0075] Q – Maximum charge for detonation in the same segment. According to Table 4, this is taken as 18.4 kg.

[0076] Table 4. Values ​​of Lithological Topography Correlation Coefficient and Seismic Attenuation Coefficient

[0077] Lithology k α hard rock 50-150 1.3-1.5 medium-hard rocks 150-250 1.5-1.8 soft rocks 250-350 1.8-2.0

[0078] In summary:

[0079] Table 5. Blasting Vibration Calculation Table

[0080]

[0081] Calculations, as shown in Table 5 (Blasting Vibration Verification Table), demonstrate that the blasting vibration velocity can be controlled within the specified safe range when the above drilling and blasting design is adopted, and the blasting design meets the requirements. (Ⅰ-1, Ⅱ, Ⅲ, Ⅳ, Ⅴ-5, Ⅵ-6)

[0082] S4. Detonation sequence: Ⅰ Cut-out hole, Ⅱ, Ⅲ, Ⅳ, Ⅴ Auxiliary hole, Ⅵ Auxiliary hole (detonated after Ⅳ), Ⅶ Peripheral hole, smooth blasting, detonated after Ⅴ.

[0083] S5, blasting vibration velocity monitoring

[0084] Monitoring methods

[0085] The blasting vibration detection employs a real-time monitoring method, with three monitoring points set up on the ground beneath the gas pipeline foundation. Through blasting monitoring, the ground particle vibration velocity at key locations along the gas pipeline is obtained and compared with the design value V = 2.0 cm / s to determine the impact of the blasting vibration on the gas pipeline.

[0086] On-site monitoring

[0087] (1) The Zhonggui gas pipeline crosses the tunnel, so measuring points are set up at the midpoints of the right line, left line and left and right lines of the tunnel respectively.

[0088] (2) Sensor Installation

[0089] ① The sensor is installed on the test pile or foundation;

[0090] ② Remove dust and dirt from the base surface and clean the surface with a brush;

[0091] ③ Arrange three sensors on the surface of the natural gas pipeline foundation according to the orientation of the three-dimensional rectangular coordinate system, in the vertical, horizontal tangential, and horizontal radial directions, and minimize the distance between the sensors. Use a conspicuous marker to mark the installation location and sensor orientation.

[0092] ④ The horizontal tangential velocity sensor and the horizontal radial velocity sensor should be on the same plane and parallel to the horizontal plane. The horizontal radial velocity sensor should point to the blasting center, and the vertical velocity sensor must be arranged perpendicular to the horizontal plane.

[0093] ⑤ The sensor is bonded with plaster. The plaster is mixed with water to form a paste, which is then evenly applied to the bottom surface of the sensor. The thickness of the paste should not exceed 1 cm, and the plaster should solidify for at least 10 minutes to form a rigid connection between the sensor and the surface of the target being measured.

[0094] S6. Analysis of Blasting Vibration Monitoring Data

[0095] Monitoring of blasting activities during tunnel construction beneath the Zhonggui natural gas pipeline was conducted using a UBOX-5016 intelligent blasting vibration monitor and velocity sensors, with the sensors deployed on the pipeline foundation. Real-time monitoring of each blast began after the blasting mileage entered the monitoring mileage. After on-site monitoring, the monitoring personnel imported the data into a computer and printed out the waveform diagrams and results tables, which were then given to the verification personnel. The verification personnel checked and verified the results against the original data and calculated the topographic and geological coefficients and attenuation indices between the blasting point and surrounding protected structures based on the verified data.

[0096] According to the relevant provisions of "the blasting vibration criteria for ground buildings, power plant (plant) central control room equipment, tunnels and roadways, high rock slopes and newly poured large-volume concrete, the peak vibration velocity and dominant frequency of the foundation mass points at the location of the protected object shall be adopted."

[0097] The main protected object near the blasting area is the gas pipeline. However, there is no safety allowable vibration velocity standard for natural gas pipelines in the relevant standards and specifications. After reviewing relevant literature, it was determined that the maximum vibration velocity of natural gas pipelines should not exceed 3 cm / s (the specific value needs to be agreed upon with the natural gas company). For the sake of safety, the design value is V = 2.0 cm / s.

[0098] During the monitoring process, the point with the largest vibration peak was selected as the early warning point for the safety and stability control of the Zhonggui natural gas pipeline. When the peak value exceeded V = 2.0 cm / s, the blasting operation was immediately stopped and the blasting parameters were adjusted.

[0099] For detailed monitoring results of blasting vibration velocity, please refer to Figure 5 :

[0100] According to the monitored blasting vibration velocity, using the above-mentioned controlled blasting parameters, the blasting vibration velocity only changes with the distance from the blasting point. The maximum peak value at the point closest to the pipeline is in the z-direction, with a value of 1.05 cm / s, which is far below the safety allowable vibration velocity standard for natural gas pipelines. The safety of the Zhonggui natural gas transmission pipeline meets the requirements.

[0101] Evaluation of Explosion Effect

[0102] Multiple blasting results showed that not only was the blasting vibration velocity controlled within the safe allowable standard, but over-excavation was also well controlled, the blast marks were clear, and the disturbance to the surrounding rock was significantly reduced.

[0103] Using the drilling and blasting method described in this application, the pass rate of one-time tunnel section formation was increased from 63.3% to 94.6% according to the test and statistics. The average over-excavation was controlled within 10cm, and the over-excavation volume per linear meter was reduced by 6.04 cubic meters compared with before the drilling and blasting parameters were changed. The overall cost saving per linear meter was 2470.7 yuan, which is a significant economic benefit.

[0104] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for constructing a new tunnel under an existing pipeline using blasting, characterized in that... Includes the following steps: S1, Drilling and blasting design; including: Explosive consumption per unit volume: 0.7 kg / m³ 3 ; Cutting method: The upper step cutting holes and the first and second ring auxiliary holes adopt horizontal wedge cutting, and the remaining auxiliary holes adopt straight cutting; the lower step adopts straight cutting, and all the surrounding holes adopt small-spacing, small-angle outward straight cutting. Hole Layout: Cut Holes: The hole spacing is 0.4m, the hole depth is 2.2m, the number of holes is 4, the charge per hole is 1.93kg, and the total charge of the 4 holes is 7.72kg; Peripheral Holes: A small-spacing, low-charge method is adopted, the hole spacing a=0.30m, the hole depth is 2.0m, the hole bottom is inclined outwards from the outline by 2°, the number of holes is 120; the charge per hole is 0.12kg, the plugging length is 0.2m, and the total charge of the 120 holes is 14.4kg; Auxiliary holes: the spacing between blast holes is 0.7-0.9m, the depth of blast holes is 2.0m, the number of blast holes is 162, the charge per hole is 0.6-0.8kg, and the maximum charge per blast is 18.4kg; S2. Charge structure layout: The slotted boreholes and auxiliary boreholes adopt a radially uncoupled continuous charge structure; the peripheral boreholes adopt a radially uncoupled, axially spaced charge structure. S3. Safety calculation of blasting vibration; Calculate the blasting vibration values ​​of each protected object at the distance from the blasting point according to Sadovsky's empirical formula: K – A coefficient related to topography and geology; α — Seismic attenuation coefficient; Q—Maximum charge for detonation in the same phase; Determine whether the blasting vibration velocity in the drilling and blasting design can be controlled within the specified safety allowable range. If so, the blasting design meets the requirements and proceed to the next step. S4, Detonation; Detonate in the following order: cut hole, auxiliary hole, and surrounding hole; Step S5, Blasting Vibration Velocity Monitoring; Blasting vibration detection adopts a real-time monitoring method. Three measuring points are set up on the ground of the gas pipeline foundation. Through blasting monitoring, the vibration velocity of ground particles at key parts of the gas pipeline is obtained and compared with the design values ​​to determine the impact of blasting vibration on the gas pipeline. Measuring points are set up at the midpoints of the right line, left line, and both lines of the tunnel. The sensor installation at the measuring points includes... The sensor is installed on the test pile or foundation; Remove dust and dirt from the surface of the test pile or foundation, and clean the surface with a brush; According to the orientation of the three-dimensional rectangular coordinate system, three sensors are arranged on the surface of the natural gas pipeline foundation in the vertical, horizontal tangential and horizontal radial directions; and the installation positions and sensor orientations are marked with a conspicuous marker. The horizontal tangential velocity sensor and the horizontal radial velocity sensor should be on the same plane and parallel to the horizontal plane. The horizontal radial velocity sensor should point to the blast center, and the vertical velocity sensor must be arranged perpendicular to the horizontal plane.

2. The method for blasting construction of a new tunnel under an existing pipeline according to claim 1, characterized in that, The sensor is bonded with plaster. The plaster is mixed with water to form a paste, which is then evenly applied to the bottom surface of the sensor. The thickness of the paste should not exceed 1 cm, and the plaster should solidify for at least 10 minutes to form a rigid connection between the sensor and the surface of the target being measured.

3. The method for blasting construction of a new tunnel under an existing pipeline according to claim 1, characterized in that, The method for constructing a new tunnel under an existing pipeline using blasting also includes step S6: analysis of blasting vibration monitoring data. After the blasting mileage enters the monitoring mileage, real-time monitoring of each blast begins. After on-site testing, the testing personnel import the data into a computer and print out the waveform diagram and test result table, which are then given to the verification personnel. The verification personnel check and verify the test results based on the original data and calculate the coefficients and attenuation index related to the terrain and geology between the blasting point and the surrounding protected buildings based on the verified test data. During the monitoring process, the point with the largest vibration peak is selected as the early warning point for the safety and stability control of the natural gas pipeline. When the peak value exceeds the safe allowable vibration velocity of the natural gas pipeline, the blasting operation is immediately stopped, and the blasting parameters are adjusted.

4. The method for blasting construction of a new tunnel under an existing pipeline according to claim 1, characterized in that, In step S1, leave one empty hole in the middle of the slot.

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