A mechanized drilling and micro-blasting method for tunnel excavation

Abstract

This invention discloses a mechanized drilling and micro-blasting excavation method for tunnels, comprising the following steps: S1: First, a microwave generating system is integrated onto the boom of a drilling device for operation. The radiator in the microwave generating system is installed behind the drill bit at the head end of the boom; S2: The drilling device is equipped with a three-dimensional laser scanner to perform three-dimensional scanning and positioning of the tunnel face, and to perform a full-area scan of the tunnel face to obtain full-area data on joint distribution. Samples are taken at different locations on the tunnel face, and full-area data on rock strength distribution are obtained through a universal testing machine. Microwave pretreatment creates an effective weakened zone in the rock mass. The weakened zone is distributed along the excavation contour, which is beneficial for achieving a better smooth blasting effect on the final outer contour, reducing over- and under-excavation, reducing equipment wear, reducing explosives, and thus reducing the construction costs increased by taking measures to treat over- and under-excavation. It also effectively reduces drilling resistance and increases drilling speed.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering technology, specifically to a mechanized drilling and micro-blasting excavation method for tunnels. Background Technology

[0002] Tunnel excavation efficiency and safety directly impact the progress and cost of major projects such as railways, highways, and water conservancy. Traditional drill-and-blast methods in hard rock formations suffer from problems such as rapid drill wear, poor blasting effects, and severe over- and under-excavation. Furthermore, blasting vibrations threaten the stability of the surrounding rock and adjacent structures. Over- and under-excavation are the most common quality and cost control issues in geotechnical engineering excavation, referring to the phenomenon where the actual excavation profile exceeds or fails to reach the design profile. This is primarily concentrated in tunnels, roadways, foundation pits, roadbed slopes, and mining scenarios. Drill-and-blast tunnel excavation is a typical high-incidence area for over- and under-excavation problems, directly affecting project quality, construction safety, schedule, and cost, and is a key construction indicator controlled within the industry.

[0003] In tunnel drilling and blasting operations, traditional rock drilling rigs have a single function, only undertaking drilling operations and lacking the ability to pre-treat the rock mass. When facing hard rock formations, drilling resistance is high, drilling speed is slow, drill bit wear is severe, and replacement frequency is high, resulting in limited construction efficiency. For complex geological conditions such as fractured areas and areas with abrupt lithological changes, the rig's hole layout relies on manual experience and cannot achieve intelligent and differentiated hole layout based on rock mass strength and joint distribution. This can easily lead to energy waste or insufficient fracturing and over- or under-excavation problems during subsequent blasting. Summary of the Invention

[0004] The purpose of this invention is to provide a mechanized drilling and micro-blasting method for tunnel excavation in order to solve the above-mentioned problems and overcome the shortcomings of the prior art, as detailed below.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a method for mechanized drilling and micro-blasting excavation of tunnels, comprising the following steps: S1: First, the microwave generating system is integrated onto the boom of the drilling device for operation. The radiator in the microwave generating system is installed behind the drill bit at the head end of the boom. S2: The drilling device is equipped with a 3D laser scanner to perform 3D scanning and positioning of the tunnel face, and to perform a full-area scan of the tunnel face to obtain full-area data on joint distribution. Sampling is performed at different locations on the tunnel face, and full-area data on rock strength distribution is obtained through a universal testing machine. Differentiated hole layout design is carried out based on the joint distribution and rock strength distribution. After generating hole layout coordinates based on the full-area data, the guide arm drives the drill bit to move to the preset hole layout position to achieve precise alignment between the drill bit and the hole layout coordinates. S3: After the drill bit is positioned, the microwave generation system is started to perform radiation pretreatment on the hole layout position. The microwave is focused on the predetermined breaking ring to form a weakened zone. Drilling operation is carried out using a synchronous drilling and microwave process to form blast holes. S4: For different types of blast holes, adjust the charge amount based on the microwave pretreatment effect and use a compound initiation network for blasting operations. Preferably, the microwave generating system in step S1 includes a microwave generator installed in the middle and rear part of the boom, and the microwave generator transmits microwaves to the radiator through the waveguide in the microwave generating system. The microwave generating system also includes a closed-loop cooling system and a PLC control system; the microwave generator has a power of 30-50kW and a frequency of 2.45GHz; the radiator is kept 15-20cm away from the rock surface under the drive of the curved arm, and the closed-loop cooling system adopts both liquid cooling and air cooling modes.

[0006] Preferably, in step S2, the differentiated hole layout design is based on the scanning results of a three-dimensional laser scanner to classify the rock surface into low-intensity, medium-intensity, high-intensity, and fracture-developed areas. The standard value for hole spacing in the low-intensity area is 80-100cm, and the row spacing is 70-90cm. The hole spacing in the medium-intensity area remains at the standard value, and the row spacing is adjusted to 65-85cm. The hole spacing in the high-intensity area is increased by 15% and the row spacing is increased by 10% based on the standard value in the low-intensity area. In the fracture-developed area, the main fracture network direction is identified by an ultrasonic fracture detector, and the hole placement position is ≥30cm away from the fracture center. At the same time, the microwave irradiation angle is adjusted to be 45°-60° with the fracture surface to avoid ineffective loss of microwave energy along the fracture.

[0007] Preferably, in step S3, the power density of the radiation pretreatment is 1.5-2.5 kW / cm², the irradiation time is 60-120 seconds / hole, the diameter of the weakened zone is 30-50 cm, and the temperature difference between the inside and outside of the rock is 300-500℃.

[0008] Preferably, in step S5, the blast hole type consists of a cut hole, a peripheral hole, and an auxiliary hole. The charge amount of the cut hole is 0.68-1.35 kg / m³, the charge amount of the peripheral hole is 0.34-1.04 kg / m³, the charge amount of the auxiliary hole is 0.51-1.22 kg / m³, and the micro-delay time of the initiation network is 25-50 ms.

[0009] Preferably, a miniature ultrasonic atomizing nozzle and a lithology sensing module are integrated at the front end of the radiator. The ultrasonic atomizing nozzle is connected to the water tank of the rock drilling rig, and the ultrasonic atomizing nozzle has a solenoid valve that controls its on / off state and is linked to the lithology sensing module.

[0010] As a preferred option, an infrared thermal imaging sensor and an ultrasonic fracture detector are integrated next to the radiator. The infrared thermal imaging monitors the changes in the rock mass temperature field in real time. The stronger the microwave absorption, the faster the temperature rises. The ultrasonic detector analyzes the degree of rock mass fracture development through reflected waves.

[0011] Preferably, a negative pressure vortex shroud is installed on the curved arm, with the shroud's exhaust port facing the gap between the drill bit and the radiator. When microwave radiation occurs, the vortex shroud activates negative pressure, forming a spiral swirling airflow that promptly removes dust and debris generated by the heated rock mass, preventing dust from obstructing the infrared thermal imaging sensor. The swirling airflow simultaneously washes the drill bit surface, preventing high-temperature drill cuttings from adhering to the drill bit's cutting edge, while also carrying away some of the drill bit's heat.

[0012] As a preferred option, an electromagnetic active vibration damper is installed at the connection between the microwave generator and the curved arm. The vibration frequency of the curved arm is monitored in real time by an acceleration sensor, and the damping force is output in the opposite direction to counteract the vibration.

[0013] The beneficial effects are: 1. Microwave pretreatment creates an effective weakened zone in the rock mass, which is distributed along the excavation contour. This facilitates a better smooth blasting effect on the final outer contour, reduces over- and under-excavation, and consequently reduces the construction costs associated with over- and under-excavation treatment. It also effectively reduces drilling resistance and increases drilling speed. Simultaneously, the synchronous drilling and microwave process reduces the hard friction between the drill bit and the rock mass, reduces drill bit wear, reduces the frequency of drill bit replacement, and improves continuous operation efficiency. Furthermore, the charge amount for different types of blast holes is precisely reduced, significantly reducing overall explosive consumption and directly lowering the cost of blasting materials. 2. The synergistic effect of differentiated hole layout design and microwave pretreatment makes the single blasting advance more uniform and extends the effective cycle advance; it accelerates the monthly tunneling progress, especially suitable for the construction of ultra-long tunnels, and significantly shortens the overall construction period; 3. The integrated trolley integrates drilling, microwave pretreatment, and blasting functions, avoiding the problems of switching between multiple equipment and poor process connection in traditional construction, realizing continuous operation from positioning to blasting, and reducing process waiting time; 4. The combined effect of the compound detonation network and microwave pretreatment effectively controls the intensity of blasting vibration, significantly reduces disturbance to the surrounding rock, and avoids risks such as collapse and over- or under-excavation caused by vibration. It is especially suitable for tunnel construction with great burial depth, high stress and proximity to sensitive buildings and structures. 5. Three-dimensional laser scanning positioning and differentiated hole layout design ensure the accuracy of blast hole layout and guarantee the quality of surrounding hole formation; microwave-guided blasting cracks extend along a predetermined path, improving the quality of tunnel outline formation and protecting the integrity of surrounding rock. 6. The electromagnetic active vibration damper at the connection between the microwave generator and the articulated arm cancels out vibration in real time through an acceleration sensor, preventing the distance between the microwave radiator and the rock surface from shifting and ensuring consistent pretreatment results; the closed-loop cooling system adopts both liquid cooling and air cooling modes to effectively prevent the microwave components from overheating and adapt to long-term high-intensity operations. 7. The spiral airflow formed by the negative pressure vortex shroud not only removes dust and debris generated by the heating of the rock mass, avoiding obstruction of the infrared thermal imaging sensor, but also washes the drill bit surface, removes some heat, prevents high-temperature drill cuttings from adhering, extends the service life of the drill bit, and ensures the accuracy of monitoring data. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structural principle of the present invention; Figure 2 This is a schematic diagram of the process flow principle of the present invention.

[0016] Figure 3 This is a schematic diagram of the arm and microwave generator of the present invention.

[0017] The following are the annotations for the attached diagrams: 1. boom; 2. drill bit; 3. microwave generator; 4. radiator; 5. waveguide; 6. 3D laser scanner; 7. electromagnetic active vibration damper; 8. infrared thermal imaging sensor; 9. ultrasonic fracture detector; 10. ultrasonic atomizing nozzle; 11. lithology sensing module; 12. negative pressure vortex hood; 13. closed-loop cooling system; 14. PLC control system. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0019] refer to Figures 1-3 As shown, this invention provides a mechanized drilling and micro-blasting excavation method for tunnels. First, a microwave generating system is integrated onto the boom 1 of the drilling device for operation. (See attached instruction manual). Figure 3As shown, the drilling device can be a rock drilling rig, and the boom 1 can be a double-bend boom of the rock drilling rig, but is not limited to a multi-bend rock drilling rig, forming an integrated platform for drilling, microwave, and blasting. The radiator 4 in the microwave generation system is installed behind the drill bit 2 at the upper end of the boom 1. The microwave generation system includes a microwave generator 3 installed in the middle and rear of the boom 1. The microwave generator 3 transmits microwaves to the radiator 4 through the waveguide 5 in the microwave generation system. The basic principle of microwave-assisted blasting is to utilize the selective heating characteristics of microwaves on rocks to pre-treat the rock mass before drilling and blasting, thereby changing its physical and mechanical properties. Specifically, when microwaves irradiate the rock mass, polar minerals such as mica and pyrite, or pore water in the rock, absorb microwave energy and rapidly convert it into heat energy. Due to the differences in the thermal expansion coefficients of different minerals, uneven thermal stress will be generated between mineral particles. When this stress exceeds the rock strength, it will induce and expand micro-cracks, thereby significantly reducing the overall strength and integrity of the rock. This creates favorable conditions for subsequent blasting: on the one hand, it can guide the blast cracks to expand in a predetermined direction, improving blasting accuracy; on the other hand, it can reduce the consumption of explosives and effectively control harmful effects such as blasting vibration.

[0020] The rock drilling rig is equipped with a 3D laser scanner to perform 3D scanning and positioning of the tunnel face, automatically identify the distribution of rock joints, obtain full-domain data of joint distribution, and then sample different locations on the tunnel face and obtain full-domain data of rock strength distribution through a universal testing machine. Based on the joint distribution and rock strength distribution, differentiated hole layout design is carried out. After generating hole layout coordinates based on the full-domain data, the guide arm drives the drill bit to move to the preset hole layout position, achieving precise alignment between the drill bit and the hole layout coordinates. Laser scanning provides comprehensive lithological data, and differentiated borehole layout ensures precise microwave radiation targeting of key areas. Microwave pretreatment weakens rock mass strength, and the combined effect of these three factors reduces drilling resistance by 40%-60%, increases drilling speed by 30%-50%, and improves the uniformity of single-blast footage by 50%. The differentiated borehole layout design is based on the scanning results of a 3D laser scanner to classify the rock surface into low-intensity, medium-intensity, high-intensity, and fracture-developed areas. The standard value for hole spacing in low-intensity areas is 80-100cm, and the row spacing is 70-90cm. The hole spacing in medium-intensity areas remains at the standard value, while the row spacing is adjusted to 65-85cm. In high-intensity areas, the hole spacing is increased by 15% and the row spacing is increased by 10% based on the standard value in low-intensity areas. In fracture-developed areas, the main fracture network is identified using an ultrasonic fracture detector, and the borehole positions are offset from the fracture center by ≥30cm. At the same time, the microwave irradiation angle is adjusted to 45°-60° with the fracture surface to avoid ineffective loss of microwave energy along the fracture.

[0021] After drill bit 2 is positioned, the microwave generation system is activated to perform radiation pretreatment on the hole locations. The power density of the radiation pretreatment is 1.5-2.5 kW / cm², the irradiation time is 60-120 seconds per hole, the diameter of the weakened zone is 30-50 cm, the temperature difference between the inside and outside of the rock is 300-500℃, and the microwave is focused on the predetermined fracture zone to form the weakened zone. The weakened zone is distributed along the excavation contour, reducing rock breakage during blasting, which is conducive to achieving a better smooth blasting effect on the final outer contour, reducing dangerous rocks on the blasting face, and thus solving the current over- and under-excavation problems. Drilling and blasting operations are carried out using a synchronous drilling and microwave process to form blast holes. The microwave pretreatment parameters are adaptively adjusted according to the lithology: granite uses a power of 45 kW, a time of 120 seconds, and a cycle interval of 15 seconds; sandstone uses a power of 35 kW, a time of 90 seconds, and continuous irradiation; limestone uses a power of 40 kW, a time of 100 seconds, and pulse mode.

[0022] For different types of blast holes, the charge amount is adjusted based on the microwave pretreatment effect. The blast hole types consist of slotted holes, peripheral holes, and auxiliary holes. In step S5, the charge amount for slotted holes is 0.68-1.35 kg / m³, for peripheral holes it is 0.34-1.04 kg / m³, and for auxiliary holes it is 0.51-1.22 kg / m³. The micro-delay time of the initiation network is 25-50 ms. The following examples are given.

[0023]

[0024] When using a compound initiation network for blasting operations, the detonating cord must not be knotted or stretched; alternatively, a new type of shaped charge detonator blasting process can be employed, with a micro-delay time of 25-50ms for the initiation network. The precise reduction of the charge amount based on microwave pretreatment combined with the 25-50ms micro-delay initiation results in a blasting vibration velocity ≤1.5cm / s, a 35% reduction compared to traditional methods. Simultaneously, explosive consumption is reduced by 25%, and blasting material costs are reduced by over 30%.

[0025] After the blasting is completed, the tunnel excavation face is cleaned and inspected, completing one round of excavation work.

[0026] In addition, to ensure the long-term stable operation of the microwave generation system, the microwave generation system also includes a closed-loop cooling system 13 and a PLC control system 14; the microwave generator 3 has a power of 30-50kW and a frequency of 2.45GHz; the radiator 4 maintains a distance of 15-20cm from the rock surface under the drive of the curved arm, and the closed-loop cooling system 13 adopts both liquid cooling and air cooling modes. The liquid cooling circuit consists of a coolant tank, a micro circulating pump, and heat dissipation pipes. The heat dissipation pipes are wrapped around the outer wall of the microwave generator and waveguide. The coolant is a 50% ethylene glycol aqueous solution with a circulation flow rate of 5-8 L / min. It absorbs the heat generated by the microwave components and delivers it to the radiator at the rear of the trolley. The air cooling circuit has micro axial flow fans with a wind speed of 3-5 m / s installed in the radiator shell and microwave generator cavity to directly blow air to dissipate heat from high-heat components. The PLC control system monitors the temperature of the microwave components in real time with a temperature measurement accuracy of ±2℃. When the temperature is >80℃, it automatically increases the liquid cooling circulation flow rate and air cooling speed. When the temperature is >100℃, it triggers a shutdown protection to ensure that the microwave system can operate continuously for ≥8 hours at a power of 30-50kW without overheating failure.

[0027] A miniature ultrasonic atomizing nozzle 10 and a lithology sensing module 11 are integrated at the front end of the radiator 4. The ultrasonic atomizing nozzle 10 is connected to the water tank of the rock drilling rig, and has a solenoid valve that controls its on / off state and is linked to the lithology sensing module 11. Different lithologies absorb microwaves at different frequencies. The lithology sensing module 11 integrated at the front end of the radiator 4 can automatically switch the microwave operating frequency based on the lithology data scanned previously. The lithology sensing module identifies different lithology types such as granite, sandstone, and limestone. The PLC control system automatically switches the microwave power and irradiation time, solving the problem of uneven pretreatment effects caused by differences in microwave absorption efficiency among different lithologies, and ensuring that the pass rate of the weakened area is ≥95%. An infrared thermal imaging sensor 8 and an ultrasonic fracture detector 9 are integrated next to the radiator 4. The infrared thermal imaging sensor 8 monitors the changes in the rock mass temperature field in real time. The stronger the microwave absorption, the faster the temperature rises. The ultrasonic fracture detector 9 analyzes the degree of rock mass fracture development through reflected waves.

[0028] A negative pressure vortex shroud 12 is installed on the curved arm. The exhaust port of the negative pressure vortex shroud 12 faces the gap between the drill bit 2 and the radiator 4. When microwave radiation occurs, the negative pressure vortex shroud 12 activates negative pressure to form a spiral vortex airflow, which promptly removes the dust and debris generated by the heated rock mass, preventing the dust from blocking the infrared thermal imaging sensor 8. The vortex airflow simultaneously washes the surface of the drill bit 2, preventing high-temperature drill cuttings from adhering to the cutting edge of the drill bit 2, while also carrying away some of the heat from the drill bit 2.

[0029] An electromagnetic active vibration damper 7 is installed at the connection between the microwave generator 3 and the curved arm. The electromagnetic active vibration damper 7 monitors the vibration frequency of the curved arm in real time through an acceleration sensor and outputs a damping force in the opposite direction to counteract the vibration.

[0030] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for mechanized drilling and micro-blasting excavation of tunnels, characterized in that, Includes the following steps: S1: First, the microwave generating system is integrated onto the boom of the drilling device for operation. The radiator in the microwave generating system is installed behind the drill bit at the head end of the boom. S2: The drilling device is equipped with a 3D laser scanner to perform 3D scanning and positioning of the tunnel face, and to perform a full-area scan of the tunnel face to obtain full-area data on joint distribution. Sampling is performed at different locations on the tunnel face, and full-area data on rock strength distribution is obtained through a universal testing machine. Differentiated hole layout design is carried out based on the joint distribution and rock strength distribution. After generating hole layout coordinates based on the full-area data, the guide arm drives the drill bit to move to the preset hole layout position to achieve precise alignment between the drill bit and the hole layout coordinates. S3: After the drill bit is positioned, the microwave generation system is started to perform radiation pretreatment on the hole layout position. The microwave is focused on the predetermined breaking ring to form a weakened zone. Drilling operation is carried out using a synchronous drilling and microwave process to form blast holes. S4: For different types of blast holes, adjust the charge amount based on the microwave pretreatment effect and use a compound initiation network for blasting operations.

2. The method for mechanized drilling and micro-blasting excavation of tunnels according to claim 1, characterized in that: The microwave generating system described in step S1 includes a microwave generator installed in the middle and rear part of the boom, and the microwave generator transmits microwaves to the radiator through a waveguide in the microwave generating system; The microwave generating system also includes a closed-loop cooling system and a PLC control system; the microwave generator has a power of 30-50kW and a frequency of 2.45GHz; the radiator is kept 15-20cm away from the rock surface under the drive of the curved arm, and the closed-loop cooling system adopts both liquid cooling and air cooling modes.

3. The method for mechanized drilling and micro-blasting excavation of tunnels according to claim 1, characterized in that: In step S2, the differentiated hole layout design is based on the scanning results of a 3D laser scanner to classify the rock surface into low-intensity, medium-intensity, high-intensity, and fracture-developed areas. The standard hole spacing in the low-intensity area is 80-100cm, and the row spacing is 70-90cm. The hole spacing in the medium-intensity area remains at the standard value, and the row spacing is adjusted to 65-85cm. The hole spacing in the high-intensity area is increased by 15% and the row spacing is increased by 10% based on the standard value in the low-intensity area. In the fracture-developed area, the main fracture network direction is identified by an ultrasonic fracture detector, and the hole placement is ≥30cm away from the fracture center. At the same time, the microwave irradiation angle is adjusted to be 45°-60° with the fracture surface to avoid ineffective loss of microwave energy along the fracture.

4. The method for mechanized drilling and micro-blasting excavation of tunnels according to claim 1, characterized in that: In step S3, the power density of radiation pretreatment is 1.5-2.5 kW / cm², the irradiation time is 60-120 seconds / hole, the diameter of the weakened zone is 30-50 cm, and the temperature difference between the inside and outside of the rock is 300-500℃.

5. The method for mechanized drilling and micro-blasting excavation of tunnels according to claim 1, characterized in that: In step S5, the blast hole types consist of cut holes, peripheral holes, and auxiliary holes. The charge amount for cut holes is 0.68-1.35 kg / m³, the charge amount for peripheral holes is 0.34-1.04 kg / m³, and the charge amount for auxiliary holes is 0.51-1.22 kg / m³. The micro-delay time of the detonation network is 25-50 ms.

6. The method for mechanized drilling and micro-blasting excavation of tunnels according to claim 1, characterized in that: A miniature ultrasonic atomizing nozzle and a lithology sensing module are integrated at the front end of the radiator. The ultrasonic atomizing nozzle is connected to the water tank of the rock drilling rig, and the ultrasonic atomizing nozzle has a solenoid valve that controls its on / off state and is linked to the lithology sensing module.

7. The method for mechanized drilling and micro-blasting excavation of tunnels according to claim 1, characterized in that: An infrared thermal imaging sensor and an ultrasonic fracture detector are integrated next to the radiator. The infrared thermal imaging monitors the changes in the rock mass temperature field in real time. The stronger the microwave absorption, the faster the temperature rises. The ultrasonic detector analyzes the degree of rock mass fracture development through reflected waves.

8. The method for mechanized drilling and micro-blasting excavation of tunnels according to claim 7, characterized in that: A negative pressure vortex shroud is installed on the curved arm, with the shroud's exhaust port facing the gap between the drill bit and the radiator. When microwave radiation occurs, the vortex shroud activates negative pressure, forming a spiral swirling airflow that promptly removes dust and debris generated by the heated rock mass, preventing dust from obstructing the infrared thermal imaging sensor. The swirling airflow simultaneously washes the drill bit surface, preventing high-temperature drill cuttings from adhering to the drill bit's cutting edge, while also carrying away some of the drill bit's heat.

9. The method for mechanized drilling and micro-blasting excavation of tunnels according to claim 1, characterized in that: An electromagnetic active vibration damper is installed at the connection between the microwave generator and the curved arm. The vibration frequency of the curved arm is monitored in real time by an acceleration sensor, and the damping force is output in the opposite direction to counteract the vibration.

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