A method of excavating a cross-measure access using a plasma torch

Abstract

The application discloses a method for excavating a connecting channel by using a plasma torch, and the method comprises the following steps: carrying out freezing construction in a stratum until a freezing wall is closed, and the soil in the excavation path of the connecting channel is frozen into a frozen soil body; drawing an excavation contour line of the connecting channel on a working face, the excavation contour line is drawn according to the excavation path of the connecting channel, and the excavation contour line is located in the enclosure of the freezing wall; S2, drawing a cutting line on the working face, the cutting line is located in the enclosure of the excavation contour line of the connecting channel; S3, cutting the frozen soil body along the cutting line by using the plasma torch to obtain a cutting groove; and S4, inserting a nozzle of the plasma torch into the cutting groove. By reasonably designing the cutting line layout and the cutting unit area and combining the high-efficiency melting and crushing of the frozen soil body by the plasma torch, the method overcomes the shortcomings of low efficiency and great difficulty of the traditional construction method, and improves the construction efficiency and safety of the connecting channel.

Description

Technical Field

[0001] This invention relates to the field of tunnel boring technology. Specifically, it is a method for tunneling connecting passages using a plasma torch. Background Technology

[0002] In subway construction, connecting passageways are indispensable supporting facilities. These passageways are typically located deep underground, and most traverse soft soil layers. Under such geological conditions, construction often requires specialized methods. Currently, the freezing method is one of the main technical means for constructing connecting passageways in soft soil layers. The freezing method lowers the soil temperature, freezing the soil into permafrost, thereby providing higher strength and stability. However, the high strength of permafrost leads to low construction efficiency and significant excavation difficulty when using traditional manual pneumatic drills. This technical bottleneck severely restricts the construction progress of connecting passageway projects.

[0003] A plasma torch, also known as a plasma spray gun or plasma torch, is a plasma generator that works by utilizing the thermal effect of high-temperature plasma. A plasma torch consists of a nozzle, electrodes, and an electrode chamber, and its outlet can generate a high-temperature gas flow with temperatures ranging from several thousand to tens of thousands of degrees Celsius.

[0004] Currently, although some devices or methods exist for applying plasma torches to tunnel excavation, such as the device provided in CN112983283B and the method provided in CN113982620A, these devices or methods are designed for tunnel construction in hard strata such as rock formations. Furthermore, plasma devices release a large amount of heat during operation, making these methods unsuitable for tunnel construction in soft strata requiring artificial freezing. In other words, a method for applying plasma torches to tunnel excavation in artificially frozen strata is still lacking. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a method for tunneling connecting passages using a plasma torch. By rationally designing the layout of the cutting lines and the area of ​​the cutting units, and combining the efficient melting and breaking of frozen soil by the plasma torch, the method overcomes the shortcomings of low efficiency and high difficulty of traditional construction methods, and improves the construction efficiency and safety of connecting passages.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for tunneling a communication passage using a plasma torch includes the following steps:

[0008] S1. Freezing construction is carried out in the stratum until the frozen walls are encircled and the soil inside the excavated rough path of the connecting passage is frozen into frozen soil; the excavation outline of the connecting passage is marked on the working face, the excavation outline is marked according to the excavated rough path of the connecting passage; the excavation outline is located within the frozen walls and the excavation outline forms a closed circle A.

[0009] S2. Draw a cutting line on the working face, the cutting line being located within the closed circle A;

[0010] S3. Use a plasma torch to cut the frozen soil along the cutting line to obtain a cutting groove;

[0011] S4. Insert the nozzle of the plasma torch into the cutting groove to heat and break up the frozen soil located between the cutting grooves;

[0012] S5. Repeat steps S2 to S4 until the communication channel is connected.

[0013] The cutting lines include transverse cutting lines, longitudinal cutting lines, oblique cutting lines, and circumferential cutting lines. The circumferential cutting lines form a closed loop B, and are parallel to the excavation outline. The transverse, longitudinal, and oblique cutting lines are all located within the closed loop B, and both ends of all transverse cutting lines connect to the circumferential cutting lines. At least one longitudinal cutting line connects to both ends of the circumferential cutting lines. The transverse cutting lines are all parallel to the horizontal plane of the connecting passage, and the longitudinal cutting lines are all perpendicular to the transverse cutting lines. Each oblique cutting line intersects with at least one of the transverse, longitudinal, and circumferential cutting lines. The closed design of the circumferential cutting lines ensures the integrity of the cutting range and reduces the risk of local collapse caused by uneven heating of the frozen soil. The interconnection of the cutting lines forms a grid structure, ensuring that after the cutting lines form cutting grooves, when the frozen soil is heated and broken along the cutting grooves using a plasma torch, the frozen soil is gradually broken along a predetermined path, improving construction stability and safety.

[0014] In the aforementioned method of tunneling a communication passage using a plasma torch, in step S2, the transverse cutting line, the longitudinal cutting line, and the oblique cutting line collectively divide the frozen soil within the closed loop B into a first cutting unit and a second cutting unit. The first cutting unit is triangular on the tunnel face, and the second cutting unit is an irregular shape formed by the oblique cutting line and the circumferential cutting line on the tunnel face. Compared to quadrilaterals or other shapes, the triangular structure is easier to detach in whole, which is beneficial for obtaining a smooth tunnel face after heating and breaking up the frozen soil.

[0015] In the aforementioned method for tunneling a communication channel using a plasma torch, in step S2, the oblique cutting lines include a first oblique cutting line and a second oblique cutting line. Each first oblique cutting line intersects with at least three points with the second oblique cutting line, and each second oblique cutting line intersects with at least three points with the first oblique cutting line. The first oblique cutting lines are parallel to each other, and the distance between any two adjacent first oblique cutting lines is equal. The second oblique cutting lines are parallel to each other, and the distance between any two adjacent second oblique cutting lines is equal. The transverse cutting lines are evenly spaced along the vertical direction of the closed loop B, and the longitudinal cutting lines are evenly spaced along the horizontal direction of the closed loop B. By maintaining equal spacing between the transverse cutting lines, the longitudinal cutting lines, and the oblique cutting lines, the shape and size of the first cutting unit can be made as consistent as possible, reducing the occurrence of local overheating or underheating, and also helping to reduce the number of times the plasma power ejected from the plasma torch needs to be adjusted.

[0016] In the above-described method of tunneling a connecting passage using a plasma torch, in step S3, the frozen soil is cut sequentially along the circumferential cutting line, the transverse cutting line, the longitudinal cutting line, and the oblique cutting line to obtain circumferential cutting grooves, transverse cutting grooves, longitudinal cutting grooves, and oblique cutting grooves, respectively. The plasma torch used for constructing the circumferential cutting groove has a power of 100-150kW; the plasma torch used for constructing the transverse, longitudinal, and oblique cutting grooves has a power of 50-80kW; the plasma torch used is a DG-FB-150kW / 600V 350A plasma torch system manufactured by Anhui Jinyi Plasma Power Technology Co., Ltd. When cutting the circumferential groove, the clamping force on the frozen soil at the excavation face is large, and cutting is easier when the plasma torch power is high. When cutting the transverse (longitudinal) groove, the frozen soil at the excavation face has already separated from the frozen wall soil in the radial direction, making cutting relatively easier; to save costs, a lower power plasma torch can be used.

[0017] In the above-described method of tunneling a connecting passage using a plasma torch, in step S4, all transverse cutting grooves are grouped into the first group, all longitudinal cutting grooves into the second group, and all oblique cutting grooves into the third group; when using the plasma torch to heat and break up the frozen soil along the cutting grooves, heating and breaking are carried out group by group.

[0018] In the aforementioned method of tunneling a communication passage using a plasma torch, in step S4, when heating and breaking up the frozen soil along the cutting groove using the plasma torch, heating and breaking are performed group by group in sequence from the first group to the third group; within the same group of cutting grooves, the frozen soil is heated and broken up sequentially along the cutting groove from the center of the tunnel face to both sides. Heating the cutting grooves in groups and in the order of "from the center to both sides" when heating and breaking up the frozen soil helps to achieve the effect of heat being dispersed and diffused from the center of the tunnel face to the periphery in stages, and also helps to ensure uniform heating of the frozen soil within the first cutting unit 10, allowing it to detach as a whole and in an orderly manner. If heating is performed in any order, or simultaneously along multiple cutting grooves, it may lead to excessive heat in some areas, resulting in damage to the frozen wall.

[0019] In the aforementioned method of tunneling connecting passages using a plasma torch, in step S2, the distance between the circumferential cutting line and the excavation outline is 400-500 mm; in step S3, the depths of the circumferential cutting groove, the transverse cutting groove, the longitudinal cutting groove, and the oblique cutting groove are 300-400 mm respectively. If the cutting groove is too shallow, the cycle advance is small, resulting in high costs and a long construction period; if the cutting groove is too deep, the efficiency of removing the broken frozen soil from the cutting groove is reduced, and the broken soil at the bottom of the cutting groove slowly accumulates and absorbs some heat energy, meaning that the energy is not fully used to remove the frozen soil at the bottom of the groove, causing unnecessary energy waste.

[0020] In the above-described method for tunneling a communication passage using a plasma torch, in step S2, within the area enclosed by the circumferential cutting line, the area of ​​the first cutting unit near the center is smaller than the area of ​​the first cutting unit near the edge; the area of ​​the first cutting unit 10 is 0.01–0.5 m². 2 .

[0021] In the above-described method of tunneling a communication channel using a plasma torch, in step S4, the nozzle of the plasma torch is inserted into the cutting groove around the first cutting unit in sequence from the center to the periphery of the tunnel face to heat and break up the frozen soil, and finally the second cutting unit is used for heating and breaking up the frozen soil.

[0022] Within the area enclosed by the circumferential cutting lines, the area of ​​the first cutting unit at the center is smaller than that at the edges. This design allows the smaller first cutting unit in the central area to break up more quickly, forming the initial failure point. Furthermore, the heat from the plasma torch is conducted outwards from the center, reducing the heating time required for the larger outer first cutting units. In addition, when the first cutting units are arranged in this manner, the frozen soil in the smaller area of ​​the first cutting unit at the center of the working face is broken up first, followed by the frozen soil in the larger outer first cutting units. This helps reduce the risk of the frozen wall melting due to excessive heat during construction, protecting the stability of the surrounding strata.

[0023] The technical solution of the present invention achieves the following beneficial technical effects:

[0024] 1. This invention overcomes the limitations of traditional pneumatic drill excavation methods, such as low efficiency, high labor intensity, and high construction difficulty, by using a plasma torch to cut and melt frozen soil with high-temperature airflow. A circumferential cutting groove isolates heat transfer between the frozen soil columns inside and outside the excavation outline. Transverse, longitudinal, and oblique cutting grooves are constructed within the area enclosed by the circumferential cutting groove, dividing the excavation face into multiple first cutting units. Furthermore, by fully designing the shape and area of ​​the first cutting units, the arrangement of first cutting units with different areas, and the crushing sequence of the first cutting units, each first cutting unit is crushed and detached from the face in an orderly manner. This eliminates the need for repeated adjustments to the plasma torch power, achieving efficient crushing of the frozen soil while preventing the heat from the plasma torch from damaging the frozen wall, ensuring the safety of the connecting tunnel excavation process and guaranteeing efficient and safe construction of connecting tunnels in soft strata.

[0025] 2. In the method provided by this invention, the layout of the cutting grooves, the shape and area design of the first cutting unit, the cutting sequence, and the dynamic adjustment of the plasma torch power work together to ensure that the heat released by the plasma torch is efficiently utilized during the frozen soil breaking process, protecting the frozen wall and preventing the disorderly detachment of the broken frozen soil blocks. Specifically, in one method provided by this invention, by rationally planning the shape and area of ​​the first cutting unit and grouping all transverse cutting grooves, all longitudinal cutting grooves, and all oblique cutting grooves into groups, when using the plasma torch to heat the frozen soil between the first cutting units along the cutting grooves, heating is carried out according to the group sequence. This ensures that the frozen soil in the first cutting units with the same area detaches from the working face almost simultaneously, while the frozen soil in the smaller and larger first cutting units detaches in batches, preventing the uncontrolled detachment of frozen soil blocks, improving construction safety, and eliminating the need for frequent adjustments to the plasma torch power during construction, thus improving construction efficiency.

[0026] 3. This invention also provides a method for dividing the first cutting unit into units with gradually increasing areas from the center of the working face outwards. In this method, the frozen soil is broken in sequence from the center of the working face outwards. This allows for the rapid melting and breaking of the small-area first cutting unit at the center of the working face, forming the initial failure point. This effectively unloads the frozen soil at the center, accelerating subsequent breaking operations and reducing the heating time required for the larger outer first cutting units to melt and break, thus effectively protecting the frozen wall. These various technical means complement each other, constructing an efficient, energy-saving, and safe construction method. Attached Figure Description

[0027] Figure 1 A schematic diagram showing the positional relationship between the frozen wall, the excavation outline, and the circumferential cutting line at the excavation face of the connecting passage in Embodiment 1 of the present invention;

[0028] Figure 2 A schematic diagram showing the positional relationship of the circumferential cutting line, transverse cutting line, longitudinal cutting line, and oblique cutting line at the excavation face of the connecting passage in Embodiment 1 of the present invention;

[0029] Figure 3 A schematic diagram showing the positional relationship between the connecting passage, the water collection well, and the support structure after construction is completed in Embodiment 1 of the present invention;

[0030] Figure 4 A schematic diagram showing the area of ​​the first cutting unit on the face of the machine in Embodiment 2 of the present invention.

[0031] The reference numerals in the figure are as follows: 1-Frozen wall; 2-Excavation outline; 3-Transverse cutting line; 4-Longitudinal cutting line; 5-Diagonal cutting line; 51-First diagonal cutting line; 52-Second diagonal cutting line; 6-Circumferential cutting line; 7-Connecting passage; 8-Support structure; 9-Water collection well; 10-First cutting unit; 11-Second cutting unit. Detailed Implementation

[0032] Example 1

[0033] This embodiment provides a method for tunneling a communication channel using a plasma torch, the specific steps of which are as follows:

[0034] 1. Freezing construction

[0035] Freezing construction is carried out in the strata. Freezing pipes are buried in the strata where the connecting tunnel is to be excavated, and the freezing pipes are located outside the excavation path of the connecting tunnel (that is, the excavation outline 2). Low-temperature brine is circulated in the freezing pipes until the strata between the freezing pipes freeze to form a ring of frozen walls (i.e., the ring of frozen walls 1). As the freezing pipes continuously transfer cold energy to the soil within the area surrounded by frozen walls 1, the soil inside the excavation path of the connecting tunnel 7 is also frozen soil.

[0036] After the frozen wall 1 is closed and the soil inside the excavated path of the connecting passage 7 is also frozen, the excavation outline 2 of the connecting passage is drawn on the working face according to the excavated path of the connecting passage 7. The excavation outline 2 forms a closed circle A, and the excavation outline 2 is located within the enclosure of the frozen wall 1.

[0037] 2. Draw the cutting line.

[0038] Cutting lines are drawn on the working face. These cutting lines include circumferential cutting lines 6, transverse cutting lines 3, longitudinal cutting lines 4, and oblique cutting lines 5. The circumferential cutting lines 6 form a closed loop B, parallel to the excavation outline 2 of the connecting passage, and spaced 400mm apart from it. Figure 1 As shown. The transverse cutting line 3, the longitudinal cutting line 4, and the diagonal cutting line 5 are all located within the closed ring B. The transverse cutting line 3 is parallel to the horizontal plane of the connecting channel 7, and the transverse cutting line 3 and the longitudinal cutting line 4 are perpendicular to each other. The diagonal cutting line 5 intersects the transverse cutting line 3 at least once, and the longitudinal cutting line 4 intersects the circumferential cutting line 6 at least once.

[0039] like Figure 2 As shown, in this embodiment, the oblique cutting line 5 includes a first oblique cutting line 51 and a second oblique cutting line 52. Each first oblique cutting line 51 and the second oblique cutting line 52 have at least 3 intersection points, and each second oblique cutting line 52 and the first oblique cutting line 51 have at least 3 intersection points. The first cutting lines 51 are parallel to each other, and the distance between any two adjacent first cutting lines 51 is equal. The second cutting lines 52 are parallel to each other, and the distance between any two adjacent second oblique cutting lines 52 is equal. The transverse cutting lines 3 are evenly distributed along the vertical direction of the closed ring B, and the longitudinal cutting lines 4 are evenly distributed along the horizontal direction of the closed ring B.

[0040] like Figure 2 As shown, in this embodiment, there are 3 horizontal cutting lines 3 and 3 vertical cutting lines 4. There are 10 diagonal cutting lines 5. The two ends of all horizontal cutting lines are connected to the two sides of the circumferential cutting line; the two ends of one vertical cutting line are connected to the top and bottom of the circumferential cutting line, respectively, and the bottom ends of the other two vertical cutting lines are connected to the axial cutting line, and the top ends are connected to the diagonal cutting lines 5.

[0041] The transverse cutting lines 3, longitudinal cutting lines 4, and diagonal cutting lines 5 together divide the frozen soil surface within the area enclosed by the circumferential cutting line 6 into multiple triangular first cutting units 10 and two irregularly shaped second cutting units 11. The second cutting unit is formed by the diagonal cutting line 5 and the circumferential cutting line 6, as shown below. Figure 2 As shown.

[0042] In this embodiment, the arrangement of the transverse cutting line 3, the longitudinal cutting line 4, and the diagonal cutting line 5 ensures that the first cutting unit 10 has only two areas with minimal difference in size. In other embodiments, the spacing between the transverse cutting lines can also be equal to the spacing between the longitudinal cutting lines, resulting in the first cutting unit 10 having only one area.

[0043] When the area of ​​the first cutting unit is different, the volume of frozen soil it contains also varies, meaning that the heat resistance of the frozen soil in the first cutting unit with different areas also varies. In this embodiment, the first cutting unit has only two areas, and the area difference between the two types of first cutting units is small. After the cutting groove is constructed, when using a plasma torch to heat and melt the frozen soil, the power of the plasma torch only needs to be changed once at most. If the area difference of the first cutting unit is too large, or if there are too many types of areas, the power of the plasma torch needs to be repeatedly adjusted when heating and melting the frozen soil to prevent the frozen soil in the smaller first cutting unit from falling off uncontrollably due to excessive heating. If a plasma torch with a lower power is used continuously, it will take more time to heat and melt the frozen soil in the larger first cutting unit, which is not conducive to improving construction efficiency.

[0044] The first cutting unit should ideally be triangular. Compared to a quadrilateral first cutting unit, placing the plasma torch in the cutting groove near the acute angle of the triangular first cutting unit to heat and break up the frozen soil results in a more concentrated stress caused by the expansion of the frozen soil. This stress is also more easily transmitted along the sides of the triangle, ultimately making it easier for the frozen soil in the first cutting unit to break up and detach completely under stress, resulting in a relatively flat working face. A relatively flat working face facilitates the next round of "marking the cutting line - constructing the cutting groove - breaking up the first cutting unit" construction. If the first cutting unit is quadrilateral or irregularly shaped, the frozen soil in the first cutting unit is easily broken into irregular shapes and detaches. In this case, to obtain a relatively flat working face, repeated breaking and adjustment of the frozen soil is required, which is complex and detrimental to improving construction efficiency.

[0045] 3. Construction cutting groove

[0046] The frozen soil was cut sequentially along circumferential cutting line 6, transverse cutting line 3, longitudinal cutting line 4, and oblique cutting line 5 using a plasma torch, forming circumferential, transverse, longitudinal, and oblique cutting grooves, respectively. The depth of each groove was 350 mm. The plasma torch used was a DG-FB-150kW / 600V 350A plasma torch system manufactured by Anhui Jinyi Plasma Power Technology Co., Ltd.

[0047] The construction of the circumferential cutting groove should be carried out first. After the circumferential cutting groove is constructed on the excavation face, an isolated frozen soil column is formed inside the circumferential cutting groove, which is separated from the surrounding frozen soil. At this time, the radial stress acting on the isolated frozen soil column is relieved, and the channel for transmitting cold energy from the frozen wall to the isolated frozen soil column in the radial direction is also cut off. The strength of the isolated frozen soil column will decrease accordingly.

[0048] When constructing cutting trenches, the power of the plasma emitted by the plasma torch should be controlled and adjusted. Specifically, when constructing circumferential cutting trenches, the plasma torch power is 100kW; when constructing transverse, longitudinal, and oblique cutting trenches, the plasma torch power is 80kW. That is, the plasma torch power for circumferential cutting trenches should be greater than that for transverse, longitudinal, and oblique cutting trenches. This is because when constructing circumferential cutting trenches, the clamping force on the frozen soil at the excavation face is large, and cutting trenches is easier with a higher plasma torch power; when cutting transverse (longitudinal) cutting trenches, the frozen soil at the excavation face has already separated from the frozen soil on the frozen wall in the radial direction, making cutting relatively easier, and the plasma torch power can be reduced to save costs.

[0049] In other embodiments, the plasma torch power used when constructing the circumferential cutting groove is in the range of 100 to 150 kW, and the plasma torch power used when constructing the transverse cutting groove, the longitudinal cutting groove, or the oblique cutting groove is in the range of 50 to 80 kW.

[0050] 4. Heat and break up the frozen soil

[0051] The nozzles of the plasma torch are inserted sequentially into the transverse cutting groove, the longitudinal cutting groove, and the oblique cutting groove. The frozen soil between the broken cutting grooves is melted by high-temperature plasma heating.

[0052] When using a plasma torch to melt and break the frozen soil between the cutting grooves (in the first cutting unit 10), a specific order should be followed. Specifically, in this embodiment, all transverse cutting grooves on the working face are grouped into a first group, all longitudinal cutting grooves into a second group, and all oblique cutting grooves into a third group. Construction personnel first use a plasma torch to heat the frozen soil in the first cutting unit along the first group of cutting grooves, and then sequentially heat the frozen soil along the second and third groups of cutting grooves. For each group of cutting grooves, the frozen soil is first heated and broken along the cutting grooves adjacent to the center of the closed circle B (i.e., the center of the excavation face of the connecting passage), and then heated and broken along the cutting grooves away from the center of the closed circle B.

[0053] like Figure 2As shown, in this embodiment, the first cutting unit 10 can be divided into two types according to its area. The first type is a smaller first cutting unit, whose three sides belong to a portion of the transverse cutting groove, the longitudinal cutting groove, and the oblique cutting groove, respectively; the second type is a larger first cutting unit, whose three sides belong to a portion of the oblique cutting groove and the other side belongs to a portion of the longitudinal cutting groove.

[0054] Taking the first cutting unit 10 in this embodiment as an example, the construction personnel first heat the frozen soil in the first cutting unit 10 along all the transverse cutting grooves, and then along all the longitudinal cutting grooves. After the longitudinal cutting grooves are heated and cut, the frozen soil at the two sides of the smaller area of ​​the first cutting unit 10 will crack under the action of the plasma torch, while the larger area of ​​the first cutting unit will remain basically stable because both sides are part of the oblique cutting grooves. Furthermore, when the construction personnel heat and break the frozen soil in the first cutting unit along the oblique cutting grooves, they can first aim the nozzle of the plasma torch at the frozen soil in the smaller area of ​​the first cutting unit 10 to heat this part of the frozen soil. The frozen soil in the smaller area of ​​the first cutting unit 10 has a smaller volume and requires less heat to melt, so this part of the frozen soil in the first cutting unit 10 will fall off first. Subsequently, the construction personnel increase the power of the plasma torch and heat and break the frozen soil in the larger area of ​​the first cutting unit 10 along the oblique cutting grooves. At this time, the frozen soil in the smaller area of ​​the first cutting unit has already fallen off, and there will be no more problems with uncontrolled falling off due to overheating. The heating and crushing of the second cutting unit 11 is carried out after the heating and crushing of all the first cutting units 10 are completed.

[0055] Taking the case of heating and breaking frozen soil along the transverse cutting groove (first set of cutting grooves) as an example, in this embodiment, the frozen soil is first heated and broken along the transverse cutting groove located near the center of the closed circle B, and then the frozen soil is heated and broken along the transverse cutting grooves located above and below the first transverse cutting groove in sequence. The same principle applies when constructing the second set of cutting grooves (longitudinal cutting grooves) and the third set of cutting grooves (oblique cutting grooves).

[0056] When heating the fractured frozen soil, the cutting grooves are heated in groups, and those belonging to the same group are heated in a "from the center outwards" sequence. This helps to achieve a gradual and dispersed heat diffusion from the center of the working face outwards, and also ensures uniform heating of the frozen soil within the first cutting unit 10, allowing the frozen soil to detach in an orderly manner. If heating is carried out in an arbitrary sequence, or simultaneously along multiple cutting grooves, it may lead to excessive heat in some areas, resulting in damage to the frozen wall.

[0057] When it is necessary to heat and break the frozen soil in the first cutting unit 10 along the oblique cutting groove first, the construction sequence of the longitudinal cutting groove can be arranged before the transverse cutting groove, so that the first cutting unit 10 with a larger area can be completely detached first; then the transverse cutting groove is heated to break and detach the frozen soil in the first cutting unit 10 with a smaller area.

[0058] In other embodiments, the construction personnel may adjust the heating sequence of the first group of cutting grooves (transverse cutting grooves), the second group of cutting grooves (longitudinal cutting grooves), and the third group of cutting grooves (oblique cutting grooves) according to actual needs. However, in general, it should be ensured that the plasma torch heats and breaks up the frozen soil along the cutting grooves in groups.

[0059] Repeat steps 2 through 4 until the connecting passage 7 is completed. After each step 4, further remove the remaining soil within the excavation outline 2, and then construct support for the exposed arch and sidewalls of the connecting passage 7. This support is temporary; permanent support will be implemented after the connecting passage is completed, resulting in a concrete support structure 8. After the permanent support is completed, stop freezing and allow the frozen walls to thaw naturally. Figure 3 This is a schematic diagram showing the locations of the connecting passage 7, the water collection well 9, and the support structure 8 after construction is completed.

[0060] Example 2

[0061] This embodiment provides a method for tunneling a communication passage using a plasma torch. The main difference between this method and that in Embodiment 1 is that, in step S2, when drawing the cutting lines, the transverse cutting lines 3, longitudinal cutting lines 4, and diagonal cutting lines 5 are not evenly spaced. That is, the transverse cutting lines 3, longitudinal cutting lines 4, and diagonal cutting lines 5 together divide the frozen soil surface within the area enclosed by the circumferential cutting lines 6 into multiple triangular first cutting units 10 with unequal areas; within the area enclosed by the circumferential cutting lines 6, the area of ​​the first cutting unit 10 near the center is smaller than the area of ​​the first cutting unit 10 near the edge. The area of ​​the first cutting unit 10 on the entire tunnel face is between 0.01 and 0.5 m². 2 Within the range, such as Figure 4 As shown.

[0062] In this embodiment, within the area enclosed by the circumferential cutting line 6, the area of ​​the first cutting unit 10 gradually increases in the direction from the center to the edge. After the cutting groove construction is completed, the volume of the frozen soil in each first cutting unit 10 also gradually increases in the direction from the center to the edge. When using a plasma torch to break up the frozen soil, the first cutting unit 10 is broken up from the center (the center of the area enclosed by the circumferential cutting line 6) towards the edge. When breaking up each first cutting unit, the plasma torch is inserted into the cutting groove around the first cutting unit to heat and melt the frozen soil in the first cutting unit. The remaining operations are the same as in Embodiment 1.

[0063] The circumferential cutting line is parallel to the excavation outline of the connecting tunnel, and the center of the area enclosed by the circumferential cutting line (closed circle B) is actually the center of the excavation face of the connecting tunnel. In this embodiment, the first cutting unit 10 in this central area has a smaller area and can be melted and broken up more quickly, forming the initial failure point. The frozen soil around the initial failure point will also absorb the heat from the plasma torch and melt to a certain extent, thereby reducing the heating time required for the larger first cutting unit 10 to melt and break up. The subsequent breaking operation speed is accelerated, thus effectively protecting the frozen wall.

[0064] Compared with Example 1, in this example, the first cutting unit 10 with a larger area (larger volume of frozen soil) is distributed near the excavation outline 2, which to some extent helps to prevent the heat from the first cutting unit 10 at the center of the working face from being transferred to the excavation outline 2 during crushing.

[0065] In this embodiment, since the area of ​​the first cutting unit 10 varies, and the area of ​​the first cutting unit 10 near the center of the working face is relatively small, if the transverse cutting groove, longitudinal cutting groove, and oblique cutting groove are grouped together according to the method in Embodiment 1, and the frozen soil in the first cutting unit is heated and melted along the cutting groove according to the group, then in order to prevent the frozen soil in the first cutting unit 10 from falling uncontrollably, a low-power plasma torch would be continuously used to heat or melt the frozen soil, or the power of the plasma torch would need to be repeatedly adjusted, which is not conducive to improving construction efficiency. Therefore, in this embodiment, the nozzle of the plasma torch is inserted into the cutting groove around the first cutting unit 10, and the frozen soil in the first cutting unit 10 is heated and broken one by one, and the frozen soil in the first cutting unit 10 is heated and broken in the order from the center of the working face to the excavation outline. When heating and breaking up the frozen soil in the first cutting unit 10, which has a smaller area at the center of the tunnel face, a high-power plasma torch is used to quickly obtain the initial failure point. At this time, because the frozen soil layer around the center is thicker, it provides a certain degree of insulation, so the high-power plasma torch is less likely to damage the frozen wall, and the frozen soil within the excavation outline is less likely to collapse as a whole. However, when heating and breaking up the frozen soil in the outer first cutting unit 10, the power of the plasma torch can be appropriately reduced. This is because the frozen soil in the outer first cutting unit 10 has already absorbed some heat, its strength has decreased, and it is easier to break up. Furthermore, a lower plasma torch power is beneficial for protecting the frozen wall.

[0066] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for tunneling a communication passage using a plasma torch, characterized in that, Includes the following steps: S1. Freezing construction is carried out in the stratum until the frozen wall (1) is encircled and the soil inside the excavation path of the connecting passage (7) is frozen into frozen soil; the excavation outline (2) of the connecting passage (7) is drawn on the working face, the excavation outline (2) is drawn according to the excavation path of the connecting passage (7); the excavation outline (2) is located within the enclosure of the frozen wall (1) and the excavation outline (2) forms a closed circle A; S2. Draw a cutting line on the working face, the cutting line being located within the closed circle A; S3. Use a plasma torch to cut the frozen soil along the cutting line to obtain a cutting groove; S4. Insert the nozzle of the plasma torch into the cutting groove to heat and break up the frozen soil located between the cutting grooves; S5. Repeat steps S2 to S4 until the communication channel (7) is connected; In step S2, the cutting lines include a transverse cutting line (3), a longitudinal cutting line (4), an oblique cutting line (5), and a circumferential cutting line (6); the circumferential cutting line (6) forms a closed loop B, and the circumferential cutting line (6) is parallel to the excavation outline (2); the transverse cutting line (3), the longitudinal cutting line (4), and the oblique cutting line (5) are all located within the closed loop B, and both ends of all the transverse cutting lines (3) are connected to the circumferential cutting line (6), and at least one longitudinal cutting line (4) has both ends connected to the circumferential cutting line (6); the transverse cutting lines (3) are all parallel to the horizontal plane of the connecting channel (7), the longitudinal cutting lines (4) are all perpendicular to the transverse cutting lines (3), and the oblique cutting line (5) has at least one intersection point with the transverse cutting line (3), the longitudinal cutting line (4), and the circumferential cutting line (6); In step S2, the transverse cutting line (3), the longitudinal cutting line (4), and the oblique cutting line (5) together divide the frozen soil within the closed circle B into a first cutting unit (10) and a second cutting unit (11); the first cutting unit (10) is triangular on the working face, and the second cutting unit (11) is an irregular shape on the working face formed by the oblique cutting line (5) and the circumferential cutting line (6).

2. The method for tunneling a communication passage using a plasma torch according to claim 1, characterized in that, In step S2, the oblique cutting line (5) includes a first oblique cutting line (51) and a second oblique cutting line (52). Each first oblique cutting line (51) and the second oblique cutting line (52) have at least 3 intersection points, and each second oblique cutting line (52) and the first oblique cutting line (51) have at least 3 intersection points. The first oblique cutting lines (51) are parallel to each other, and the distance between any two adjacent first oblique cutting lines (51) is equal. The second oblique cutting lines (52) are parallel to each other, and the distance between any two adjacent second oblique cutting lines (52) is equal. The transverse cutting lines (3) are evenly distributed along the vertical direction of the closed ring B, and the longitudinal cutting lines (4) are evenly distributed along the horizontal direction of the closed ring B.

3. The method for tunneling a communication passage using a plasma torch according to claim 2, characterized in that, In step S3, the frozen soil body is cut sequentially along the circumferential cutting line (6), the transverse cutting line (3), the longitudinal cutting line (4), and the oblique cutting line (5) to obtain circumferential cutting grooves, transverse cutting grooves, longitudinal cutting grooves, and oblique cutting grooves, respectively; the power of the plasma torch used when constructing the circumferential cutting groove is 100-150kW; the power of the plasma torch used when constructing the transverse cutting groove, the longitudinal cutting groove, and the oblique cutting groove is 50-80kW.

4. The method for tunneling a communication passage using a plasma torch according to claim 3, characterized in that, In step S4, all the transverse cutting grooves are grouped into a first group, all the longitudinal cutting grooves are grouped into a second group, and all the oblique cutting grooves are grouped into a third group; when the plasma torch is used to heat and break up the frozen soil along the cutting grooves, the heating and breaking are carried out group by group.

5. The method for tunneling a communication passage using a plasma torch according to claim 4, characterized in that, In step S4, when the plasma torch is used to heat and break up the frozen soil along the cutting groove, the heating and breaking are carried out in the order from the first group to the third group; in the same group of cutting grooves, the frozen soil is heated and broken up along the cutting groove in the order from the center of the working face to both sides.

6. The method for tunneling a communication passage using a plasma torch according to claim 4, characterized in that, In step S2, the distance between the circumferential cutting line (6) and the excavation outline (2) is 400-500mm; in step S3, the depths of the circumferential cutting groove, the transverse cutting groove, the longitudinal cutting groove and the oblique cutting groove are 300-400mm respectively.

7. The method for tunneling a communication passage using a plasma torch according to claim 1, characterized in that, In step S2, among all the first cutting units (10), the area of ​​the first cutting unit (10) adjacent to the center of the working face is less than or equal to the area of ​​the first cutting unit (10) away from the center of the working face; the area of ​​the first cutting unit (10) is 0.01~0.5m². 2 .

8. The method for tunneling a communication passage using a plasma torch according to claim 7, characterized in that, In step S4, the nozzle of the plasma torch is inserted into the cutting groove around the first cutting unit (10) in the order from the center to the periphery of the working face to heat and break the frozen soil, and finally the second cutting unit (11) is heated and broken.

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