A ventilation arrangement structure for constructing small-spacing tunnel groups beside existing tunnels

Abstract

The utility model discloses a ventilation arrangement structure of small distance tunnel group construction beside existing tunnel, including a plurality of pressure -in type fan, a plurality of jet fan and a plurality of air -blocking curtain, the pressure -in type fan realizes the ventilation of corresponding operation surface through corresponding air passage, the jet fan sets up at the intersection or the turning position between the tunnel, the air -blocking curtain sets up at the intersection position between the second tunnel and the rest tunnel. For the small distance hole group multiple operation surface of adjacent existing line, through the pressure -in type fan and the air passage of corresponding each working face, and the air passage changes along with the construction progress, realizes the ventilation of each working face to guarantee the whole ventilation effect, is provided with the jet fan in the intersection of tunnel or the turning position, is used for guaranteeing the discharge of tunnel dirty air, and at the same time, is provided with the air -blocking curtain for blocking dirty air, avoids the mutual influence ventilation effect of the intercommunication.

Description

Technical Field

[0001] This utility model belongs to the field of ventilation technology in railway tunnel group construction, specifically relating to a ventilation arrangement structure for a small-clearance tunnel group constructed next to an existing tunnel. Background Technology

[0002] During tunnel construction, ventilation structures are typically installed to supply fresh air and cool the tunnel. The effectiveness of ventilation directly affects the health and work efficiency of construction workers. Previous tunnel construction rarely involved the simultaneous parallel construction of multiple tunnels with small clearances between existing lines and newly built tunnels. In such cases, due to the numerous work surfaces within the tunnel and the concentration of construction personnel, machinery, and vehicles inside, as well as the complex transitions between work processes, a ventilation arrangement is needed to ensure a continuous supply of fresh air to the multiple work surfaces within the tunnel. Utility Model Content

[0003] This utility model proposes a ventilation arrangement structure for constructing a small-clearance tunnel group next to an existing tunnel, in order to ensure ventilation of multiple work faces during the construction of the small-clearance tunnel group adjacent to the existing tunnel.

[0004] Therefore, the technical solution adopted by this utility model is as follows: a ventilation arrangement structure for constructing a small-clearance tunnel group next to an existing tunnel. The multi-line tunnel group includes an existing first tunnel, a second tunnel, and a third, fourth, and fifth tunnel to be constructed. The third tunnel is a new passage tunnel after the second tunnel near its entrance is abandoned. The fourth tunnel overlaps with the second tunnel near its entrance. The first, third, and fourth tunnels are arranged side by side. The entrance of the fifth tunnel is located on the side of the fourth tunnel away from the third tunnel, and the end of the fifth tunnel away from its entrance merges into the second tunnel. The entrance of the second tunnel is located between the third and fourth tunnels. The multi-line tunnels are arranged in sequence along the tunnel entrances, with a first construction passage, a second construction passage, a third construction passage, and a fourth construction passage. The first, second, and third construction passages are all located within the overlapping section between the fourth and second tunnels. The first, second, and third construction passages are all synchronously connected to the second, third, fourth, and fifth tunnels. The fourth construction passage connects the second and fourth tunnels.

[0005] The third tunnel has a fifth working face, a first working face, a second working face, and a third working face arranged sequentially from the tunnel entrance inwards. The fourth tunnel has a seventh working face and a fourth working face arranged sequentially from the tunnel entrance inwards. The fifth tunnel has a sixth working face arranged from the tunnel entrance inwards. The first working face is connected to the first construction passage, the second working face is connected to the second construction passage, the third working face is connected to the third construction passage, and the fourth working face is connected to the fourth construction passage.

[0006] The ventilation arrangement structure includes several forced-in fans, several jet fans, and several air-blocking curtains. The forced-in fans achieve ventilation of the corresponding working face through corresponding air channels. The jet fans are set at the intersections or turning points between tunnels. The air-blocking curtains are set at the intersections between the second tunnel and the other tunnels.

[0007] As a preferred embodiment of the above scheme, the ventilation duct includes four stages of ventilation ducts, wherein the first stage ventilation duct is used for ventilation during the construction of the third, fourth, and fifth tunnels after the construction of each construction channel is completed. It includes a first air duct, a second air duct, and a third air duct that are respectively connected to a forced-flow fan. The first air duct is configured as a duct extending along the fifth tunnel to the sixth working face. At the same time, the first air duct is connected in parallel at the first construction channel to a duct that passes through the first construction channel and extends to the first working face. The second air duct is configured as a duct that passes through the fourth construction channel from the tunnel entrance of the second tunnel and extends to the fourth working face. At the same time, the second air duct is connected in parallel at the third construction channel to a duct that passes through the third construction channel and extends to the third working face. The third air duct is configured as a duct that extends from the tunnel entrance of the second tunnel to the second working face.

[0008] The second-stage ventilation system is used to provide ventilation during the construction of the third, fourth, and fifth tunnels after backfilling on the side of the second tunnel near the tunnel entrance. It includes a fourth, fifth, sixth, seventh, and eighth ventilation duct connected to a forced-flow fan. The fourth ventilation duct is a duct extending along the fifth tunnel to the sixth working face. At the same time, the fourth ventilation duct is connected in parallel at the first construction passage to a duct that passes through the first construction passage and extends to the first working face. The fifth ventilation duct is a duct that passes through the first and fourth construction passages from the tunnel entrance of the fifth tunnel to the fourth working face. At the same time, the fifth ventilation duct is connected in parallel at the third construction passage to a duct that passes through the third construction passage and extends to the third working face. The sixth ventilation duct is a duct that passes through the first construction passage from the tunnel entrance of the fifth tunnel to the second working face. The seventh ventilation duct is a duct that extends from the tunnel entrance of the fourth tunnel to the seventh working face. The eighth ventilation duct is a duct that extends from the tunnel entrance of the third tunnel to the fifth working face.

[0009] The third-stage ventilation duct is used for ventilation during the construction of the fourth and fifth tunnels after multiple working faces on the third tunnel are connected and the sixth working face is located on the side of the second cross passage away from the tunnel entrance. It includes the ninth, tenth, and eleventh ventilation ducts, which are respectively connected to the forced-flow fans. The ninth ventilation duct is a duct that extends along the fifth tunnel to the sixth working face. The tenth ventilation duct is a duct that extends from the tunnel entrance of the fifth tunnel through the second and fourth construction passages to the fourth working face. The eleventh ventilation duct is a duct that extends along the fourth tunnel to the seventh working face.

[0010] The fourth stage is used for ventilation during the construction of the fourth tunnel after the fifth tunnel is completed. It includes the twelfth and thirteenth ventilation ducts, which are respectively connected to the forced-in fans. The forced-in fans of the twelfth ventilation duct are set at the cross section of the fifth tunnel. The twelfth ventilation duct is a duct that is connected to the corresponding forced-in fans and extends to the fourth working face after passing through the third and fourth construction passages. The thirteenth ventilation duct is a duct that extends along the fourth tunnel to the seventh working face.

[0011] Further optimization involves reusing the forced ventilation fans in different stages, with the forced ventilation fans located outside the tunnel positioned near the fifth tunnel.

[0012] Further preferred, in the first stage, the third ventilation duct is connected in parallel with the second construction passage and extends to the side of the sixth working face after passing through the second construction passage; in the second stage, the sixth ventilation duct is connected in parallel with the second construction passage and extends to the side of the sixth working face after passing through the second construction passage; in the third stage, an eighth working face connected to the third construction passage is provided in the fifth tunnel, and a fourteenth ventilation duct is also included, wherein the fourteenth ventilation duct is a ventilation duct that extends from the tunnel entrance of the fifth tunnel through the second and third construction passages and extends to the eighth working face.

[0013] In a further preferred embodiment, a fifth construction passage is provided at the end of the second tunnel away from the tunnel entrance, which is connected to the fourth tunnel. A ninth working face is provided in the fourth tunnel, which is constructed through the fifth construction passage. A tenth working face is provided at the end of the second tunnel away from the tunnel entrance, which faces the third tunnel. Ventilation of the ninth and tenth working faces is achieved through ventilation components provided in the second tunnel.

[0014] Further preferably, the ventilation assembly includes a fan frame, a damper, and an air curtain installed in the second tunnel. Two forced-in fans are installed outside the damper. The other end of the forced-in fans is connected to the outside through the sixth construction channel and the construction inclined shaft on the side of the fourth tunnel closest to the tunnel entrance. The sixth construction channel is used to connect the construction inclined shaft with the end of the second tunnel away from the tunnel entrance.

[0015] Further preferably, the interval between the first construction passage, the second construction passage, and the third construction passage is between 200 and 300 meters.

[0016] Further optimization is that the distance between adjacent jet fans is between 400-500m.

[0017] The beneficial effects of this utility model are as follows: For multiple working faces in a group of tunnels with small clearances near existing railway lines, ventilation of each working face is achieved through forced-in fans and corresponding air ducts for each working face, and the air ducts are changed as the construction progresses, thereby ensuring the overall ventilation effect; jet fans are installed at the intersections or turning points of the tunnels to ensure the discharge of polluted air in the tunnels, and air curtains are installed to block polluted air and prevent it from spreading and affecting the ventilation effect. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the location of the multi-line tunnel in this utility model.

[0019] Figure 2 for Figure 1 A schematic diagram of the interrupted section 1 (i.e., the opening).

[0020] Figure 3 for Figure 1 A schematic diagram of interrupted surface 2.

[0021] Figure 4 for Figure 1 A schematic diagram of cross-section 3.

[0022] Figure 5 for Figure 1 A schematic diagram of the interrupted surface 3-1.

[0023] Figure 6 for Figure 1 A schematic diagram of cross-section 4.

[0024] Figure 7 for Figure 1 A schematic diagram of cross section 5.

[0025] Figure 8 for Figure 1 A schematic diagram of cross section 11.

[0026] Figure 9 for Figure 1 A schematic diagram of cross-section 6.

[0027] Figure 10 for Figure 1 A schematic diagram of cross-section 7.

[0028] Figure 11 for Figure 1 A schematic diagram of interrupted surface 8.

[0029] Figure 12 for Figure 1 A schematic diagram of cross-section 9.

[0030] Figure 13 for Figure 1 A schematic diagram of cross-section 10.

[0031] Figure 14 This is a construction schematic diagram of the multi-line tunnel in this utility model.

[0032] Figure 15 This is a schematic diagram of the wind tunnel in the first stage.

[0033] Figure 16 This is a schematic diagram of the wind tunnel during the second stage.

[0034] Figure 17 This is a schematic diagram of the wind tunnel in the third stage.

[0035] Figure 18 A schematic diagram of the ventilation channel when the third tunnel is completed.

[0036] Figure 19 This is a construction schematic diagram of a large-span section in a multi-line tunnel according to this utility model.

[0037] Attached reference numerals: First Tunnel-1, Second Tunnel-2, Third Tunnel-3, Fourth Tunnel-4, Fifth Tunnel-5, First Construction Access Road-6, Second Construction Access Road-7, Third Construction Access Road-8, Fourth Construction Access Road-9, Fifth Construction Access Road-10, Sixth Construction Access Road-11, First Ventilation Duct-12, Second Ventilation Duct-13 and Third Ventilation Duct-14, Fourth Ventilation Duct-15, Fifth Ventilation Duct-16, Sixth Ventilation Duct-17, Seventh Ventilation Duct-18, Ninth Ventilation Duct-20, Tenth Ventilation Duct-21, Eleventh Ventilation Duct-22, Twelfth Ventilation Duct-23. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments and accompanying drawings:

[0039] like Figure 1-8 As shown, a ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel is illustrated. Figure 1 and Figure 2 As shown, the multi-track tunnel system consists of the existing first tunnel 1 and second tunnel 2, and the third tunnel 3, fourth tunnel 4, and fifth tunnel 5, which require construction. The first, third, and fourth tunnels are arranged side-by-side. The entrance of the second tunnel is located between the third and fourth tunnels. The entrance of the fifth tunnel 4 is located on the side of the fourth tunnel 4 furthest from the third tunnel 3. The end of the fifth tunnel furthest from its entrance merges with the second and third tunnels, meaning the main tunnels of the fifth and second tunnels merge, and the adjacent distance between them is small. The fourth tunnel overlaps with the second tunnel at its entrance. The third tunnel is a new passageway after the second tunnel's entrance end near its entrance is abandoned; that is, the entrance sections of the second and fourth tunnels partially overlap, therefore the entrance section of the second tunnel needs to be abandoned.

[0040] To expedite construction, ensure progress, and minimize downtime, the tunnel complex will be constructed with four construction access channels (6, 7, 8, and 9) sequentially extending inwards from the tunnel entrances. Ideally, the intervals between these channels should be between 200-300 meters, and all three channels should be located within the overlapping sections of the second and fourth tunnels. These channels should simultaneously connect to the second, third, fourth, and fifth tunnels, while the fourth channel connects to both the second and fourth tunnels.

[0041] Throughout the construction process, multiple working faces will be set up within the tunnel complex. Specifically: a tenth working face will be set up at the end of the second tunnel furthest from the tunnel entrance, facing the construction of the third tunnel. Within the third tunnel, from the tunnel entrance inwards, there will be a fifth, a first, a second, and a third working face in sequence. Within the fourth tunnel, from the tunnel entrance inwards, there will be a seventh and a fourth working face in sequence, and a ninth working face will be set up within the fourth tunnel, operating through a fifth construction access road. A sixth working face will be set up within the fifth tunnel, from the tunnel entrance inwards. The first working face connects to the first construction access road, the second working face connects to the second construction access road, the third working face connects to the third construction access road, and the fourth working face connects to the fourth construction access road.

[0042] To expedite the completion of the fifth tunnel, an eighth working face is also constructed within the fifth tunnel, connecting to the junction of the third and fifth tunnels via the third construction tunnel. A fifth construction passage 10, connecting to the fourth tunnel, is located at the end of the second tunnel furthest from its entrance. Correspondingly, a ninth working face, constructed via the fifth construction passage, is located within the fourth tunnel. A tenth working face, facing the third tunnel, is located at the end of the second tunnel furthest from its entrance. Ventilation for the ninth and tenth working faces is achieved through ventilation components installed within the second tunnel. The first to tenth working faces are as follows: Figure 3 The circled numbers in the diagram represent the corresponding working surfaces.

[0043] The ventilation arrangement structure includes several forced-flow fans, several jet fans, and several air-blocking curtains. The forced-flow fans achieve ventilation for the corresponding work face through corresponding air channels. The jet fans are set at the intersections or turning points between tunnels, and the distance between adjacent jet fans is between 400-500m. The air-blocking curtains are set at the intersections between the second tunnel and the other tunnels.

[0044] The ventilation ducts are set up in sections according to the specific construction. Specifically, the ventilation ducts include four stages, with the first stage being as follows: Figure 4As shown, ventilation during the construction of the third, fourth, and fifth tunnels after the completion of construction in each construction passage is achieved includes a first ventilation duct 12, a second ventilation duct 13, and a third ventilation duct 14, each connected to a forced-draft fan. The first ventilation duct is configured as a duct extending along the fifth tunnel to the sixth working face, and simultaneously, at the first construction passage, a duct passing through the first construction passage and extending to the first working face is connected in parallel to the first ventilation duct. The second ventilation duct is configured as a duct extending from the tunnel entrance of the second tunnel through the fourth construction passage to the fourth working face, and simultaneously, at the third construction passage, a duct passing through the third construction passage and extending to the third working face is connected in parallel to the second construction passage. The third ventilation duct is configured as a duct extending from the tunnel entrance of the second tunnel to the second working face, and to expedite the connection of the fifth tunnel from its entrance to the second construction passage, the third ventilation duct is connected in parallel at the second construction passage to a duct passing through the second construction passage and extending to the opposite side of the sixth working face.

[0045] like Figure 5 As shown, the second-stage ventilation ducts are used to facilitate ventilation during the construction of the third, fourth, and fifth tunnels after backfilling on the side of the second tunnel near the tunnel entrance, and simultaneously after the section from the tunnel entrance of the fifth tunnel to the first construction passage has been completed. These ventilation ducts include the fourth ventilation duct 15, the fifth ventilation duct 16, the sixth ventilation duct 17, the seventh ventilation duct 18, and the eighth ventilation duct 19, which are respectively connected to a forced-flow fan. The fourth ventilation duct 15 extends along the fifth tunnel 5 to the sixth working face, and is connected in parallel at the first construction passage 6 to a duct that passes through the first construction passage 6 and extends to the first working face. The fifth ventilation duct 16 extends from the tunnel entrance of the fifth tunnel 5 through the first construction passage 6 and the fourth construction passage 9 to the fourth working face, and is connected in parallel at the third construction passage 8 to a duct that passes through the third construction passage 8 and extends to the third working face. The seventh ventilation duct 18 extends from the tunnel entrance of the fourth tunnel 4 to the seventh working face. The eighth ventilation duct 19 extends from the tunnel entrance of the third tunnel 3 to the fifth working face. The sixth ventilation duct 17 extends from the tunnel entrance of the fifth tunnel through the first construction passage 6 to the second working face. At the same time, in order to speed up the connection of the fifth tunnel from the tunnel entrance to the second construction passage, the sixth ventilation duct 17 is connected in parallel with a ventilation duct that extends through the second construction passage 7 and to the side of the sixth working face.

[0046] like Figure 6As shown, the third-stage ventilation ducts are used to connect multiple work faces on the third tunnel. Meanwhile, the section from the tunnel entrance of the fifth tunnel to the second construction passage has been completed. Ventilation during the construction of the fourth and fifth tunnels includes the ninth ventilation duct 20, the tenth ventilation duct 21, and the eleventh ventilation duct 22, which are respectively connected to forced-air fans. The ninth ventilation duct 20 extends along the fifth tunnel 5 to the sixth work face. The tenth ventilation duct 21 extends from the tunnel entrance of the fifth tunnel 5 through the second construction passage 7 and the fourth construction passage 9 to the fourth work face. The eleventh ventilation duct 22 extends along the fourth tunnel 4 to the seventh work face. To expedite the completion of the fifth tunnel, a fourteenth ventilation duct 25 is also included, extending from the tunnel entrance of the fifth tunnel 5 through the second construction passage 7 and the third construction passage 8 to the eighth work face.

[0047] like Figure 7 As shown, the fourth stage is used for ventilation during the construction of the fourth tunnel after the fifth tunnel is completed. It includes a twelfth ventilation duct 23 and a thirteenth ventilation duct 24, respectively connected to the forced-in ventilation fan. The forced-in ventilation fan of the twelfth ventilation duct 23 is located at the span of the fifth tunnel. The twelfth ventilation duct 23 is a duct connected to the corresponding forced-in ventilation fan and extends to the fourth working face after passing through the third construction passage 8 and the fourth construction passage 9. The thirteenth ventilation duct 24 is a duct extending along the fourth tunnel 4 to the seventh working face.

[0048] The forced-air fans in different stages can be reused, meaning that the same forced-air fan can be connected to the air ducts in different stages. For example, the first, fourth, and ninth air ducts can all be supplied with air by the same forced-air fan. For ease of management, the forced-air fans located outside the tunnel should be installed adjacent to each other, preferably near the location of the fifth tunnel.

[0049] The ventilation system includes a fan frame, a damper, and a curtain installed in the second tunnel. A forced-in fan is installed outside the damper. The other end of the forced-in fan is connected to the outside through the sixth construction passage 11 and the construction inclined shaft on the side of the fourth tunnel closest to the tunnel entrance. The sixth construction passage is used to connect the construction inclined shaft to the end of the second tunnel away from the tunnel entrance.

[0050] like Figure 3 As shown, the construction method for a multi-track tunnel group includes the following steps:

[0051] The first step is the construction of the access roads. Using the second tunnel, construction of access roads 6, 7, 8, and 9 will proceed sequentially inwards from the tunnel entrance, with the first, second, and third access roads all located within the overlapping section of the fourth and second tunnels. The first, second, and third access roads will simultaneously connect to the second, third, fourth, and fifth tunnels, while the fourth access road will connect to the second and fourth tunnels. While the access roads are being constructed, construction of the fifth tunnel will begin simultaneously from its entrance inwards. At this stage, vehicle access will be via the second tunnel.

[0052] The second step involves the construction of the third and fifth tunnels. After the construction of the section of the fifth tunnel from its connection with the first construction passage to the tunnel entrance is completed, the section of the second tunnel from its connection with the first construction passage to the tunnel entrance will be backfilled. After the construction of the second construction passage is completed, construction will proceed through the second construction passage towards the tunnel entrance of the fifth tunnel. This will ensure that the section of the fifth tunnel intersecting with the second construction passage is completed first, allowing passage through the fifth tunnel after the tunnel entrance section of the second tunnel is backfilled.

[0053] Meanwhile, after the fourth construction channel is completed, the fourth tunnel will be constructed in the direction away from the tunnel entrance through the fourth construction channel, that is, construction will be carried out inward through the fourth construction channel until it is connected to the main tunnel.

[0054] Meanwhile, after the completion of the first, second, and third construction channels, the third tunnel will be constructed inward through the first, second, and third construction channels respectively. By carrying out construction on multiple working faces, the opening of the third tunnel will be accelerated.

[0055] The third step involves the construction of the third, fourth, and fifth tunnels. When the third tunnel is constructed to connect with the second tunnel via the third construction passage, the area between the connection point of the second tunnel and the connection point with the fourth construction passage will be backfilled.

[0056] After the backfilling of the tunnel entrance section of the second tunnel is completed, that is, after the backfilling between the intersection of the second tunnel and the first construction passage and the tunnel entrance is completed, the construction of the third tunnel will begin from the tunnel entrance and proceed inward to complete the breakthrough of the third tunnel. After the third tunnel is completed, the remaining part of the entrance section of the second tunnel will be backfilled.

[0057] After the backfilling of the tunnel entrance section of the second tunnel is completed, that is, after the backfilling between the intersection of the second tunnel and the first construction passage and the tunnel entrance is completed, construction will proceed from the tunnel entrance of the fourth tunnel inward until the construction of the fourth tunnel is completed, that is, until it is connected to the main tunnel of the fourth tunnel.

[0058] After the construction between the second construction passage and the tunnel entrance in the fifth tunnel is completed, the fifth tunnel will continue to be constructed inward until it merges with the third and second tunnels.

[0059] To further expedite construction, a fifth construction access road 10 is also being constructed concurrently. This fifth access road connects the ends of the second and fourth tunnels furthest from their entrances and is located in a section of the second tunnel that does not require abandonment. Once the fifth access road is completed, construction on the fourth tunnel towards its entrance will proceed via it. To quickly access the side of the second tunnel furthest from its entrance, a sixth construction access road 11, connecting to the second tunnel, is located at the construction shaft closest to the entrance of the fourth tunnel. To expedite the breakthrough of the fifth tunnel, while construction is underway inside the second construction access road, construction on the fifth tunnel towards the point where it intersects with the third tunnel is simultaneously being carried out via a third construction access road.

[0060] During the construction of the new tunnels, mechanical excavation was used for the third, fourth, and fifth tunnels. Simultaneously, during the construction of the third tunnel, the invert and filling followed the excavation of the tunnel face. Except for the section connecting to the first construction access road and the tunnel entrance, the remaining secondary lining work was carried out after the third tunnel's entrance connected to the second tunnel. During the construction of the fifth tunnel, except for the section connecting to the first construction access road and the tunnel entrance, the remaining secondary lining work was carried out after the secondary lining of the third tunnel was completed, followed by multi-face construction. During the construction of the fourth tunnel, except for the section connecting to the first construction access road and the tunnel entrance, the remaining secondary lining work was carried out after the fourth tunnel was connected to the main tunnel.

[0061] Since the second tunnel is a single-track tunnel and the fourth tunnel is a double-track tunnel, a section of the second tunnel will be entirely within the fourth tunnel. When the second tunnel is completely within the outline of the fourth tunnel, no backfilling is required; the remaining sections require backfilling. During the backfilling of the second tunnel, at the overlap with the third tunnel, the portion outside the outline of the third tunnel will be backfilled with concrete, while the portion inside the outline will be backfilled with foamed lightweight soil. Between the point where the second and third tunnels begin to overlap and the point where the second tunnel completely separates from the fourth tunnel, a retaining wall combined with foamed lightweight soil will be used for backfilling. Between the point where the second tunnel completely separates from the fourth tunnel and the point where the second tunnel is entirely within the fourth tunnel, the portion outside the outline of the fourth tunnel or fourth construction passage will be backfilled with foamed lightweight soil, while the portion inside the outline will be backfilled with soil and rock. Between the point where the second tunnel begins to be completely within the fourth tunnel and the tunnel entrance of the second tunnel, the portion outside the outline of the fourth tunnel will be backfilled with concrete, while the portion inside the outline will be backfilled with soil and rock.

[0062] Throughout the construction process, since the first tunnel and the third tunnel are close to each other, and the first tunnel is an existing tunnel, in order to reduce the impact of the construction of the third tunnel on the first tunnel, it is necessary to use the time when the first tunnel is not open to traffic to carry out corrugated plate lining and treatment of defects in the third tunnel before the construction of the third tunnel.

[0063] This construction method has been implemented. At the tunnel entrance, the distance between the first and third tunnels is 5.94m, the distance between the third and second tunnels is 0.54m, the distance between the second and fourth tunnels is 0.75m, and the distance between the fourth and fifth tunnels is 2.14m. The distance between adjacent tunnel entrances, the first construction access road, the second construction access road, and the third construction access road is 200-300m.

[0064] When the first tunnel is widened and then the second tunnel is rerouted and incorporated into the first tunnel, the first tunnel will be shut down for 12 months initially, and the second tunnel for 21 months later, for a total shutdown of 33 months. With this construction method, the first tunnel does not need to be modified, and only the second tunnel needs to be shut down for 9.4 months. When the third tunnel is completed, although the newly built tunnel is not fully completed, the third tunnel can be opened to traffic, that is, the existing line can be opened to traffic. Therefore, the overall shutdown time is less and the impact on travel is reduced.

[0065] The overall construction length of the third tunnel is 1245m. 966m of this section, near the tunnel entrance, is constructed from the entrance inwards. The remaining 264m on the other side is where the fifth tunnel merges with the second and third tunnels, and construction begins from the second tunnel towards the entrance. This section is the branching and large-span section, divided into four segments based on cross-sectional span: the switch section, the Vb double-track branching section, the second-largest span VK1 section, and the large-span VK2 section. The switch section has turnouts, and the large-span VK2 section completely separates the two tracks. The spans of the switch section, the Vb double-track branching section, the second-largest span VK1 section, and the large-span VK2 section increase sequentially. Before the large-span VK2 section, there is a section of the third tunnel marked as Vb-D branching single track. The project consists of four sections with different spans, and is excavated in sections to reduce the disturbance of the rock strata caused by stress changes due to excessive cross-sectional changes. This effectively reduces the need for time-consuming support such as anchor cables, and facilitates a reduction in the excavation time.

[0066] The switch machine section, the Vb double-track branching section, the second largest span VK1 section, and the Vb-D branching single track were all constructed using the step method, while the large span VK2 section was constructed using the central partition wall CD method. The secondary lining of the second largest span VK1 section and the large span VK2 section was constructed using a mobile full-span combined formwork system, the Vb double-track branching section used a secondary lining formwork trolley, and the switch machine section and the Vb-D branching single track used a single trolley frame for secondary lining formwork trolley construction. The end spans of the switch machine section, the Vb double-track branching section, the second largest span VK1 section, and the large span VK2 section are all larger than the single-track span of the second tunnel, therefore, widening excavation is required. The excavation sequence for the branching sections and large span sections is: Vb double-track branching section, second largest span VK1 section, large span VK2 section, Vb-D branching single track, and switch machine section.

[0067] The widening and excavation of the Vb double-track branch section, the second largest span VK1 section, and the switch machine section includes the following steps:

[0068] Step 1: Under the previous cycle of advanced support, remove the existing tunnel arch lining of the upper bench, then excavate the upper benches on both the left and right sides, and construct the initial support for the upper benches.

[0069] Step 2: Remove the existing tunnel sidewalls and invert arch at the bottom, then excavate the middle and lower benches on both sides and construct the initial support for the middle and lower benches.

[0070] Step 3: Expand the excavation of the left and right inverted arch sections, construct the initial support for the inverted arch, and then construct the inverted arch lining, side walls, and arch lining in sequence.

[0071] During construction, the advance per cycle for the upper steps shall not exceed two arch frames, the advance per cycle for the middle and lower steps shall not exceed three arch frames, the excavation shall be staggered by three arch frames on the left and right sides, and the advance per cycle for the invert arch shall not exceed five arch frames.

[0072] like Figure 8 As shown in the figure, the circled numbers indicate the excavation sequence. The excavation of the large-span VK2 section includes the following steps:

[0073] Step 1: Construct advanced support pipes within the arch area of ​​the existing tunnel, then excavate the upper right bench, and simultaneously install upper bench vertical supports on the left side of the enlarged upper bench; the vertical supports are steel frames, and concrete is sprayed on the vertical supports to serve as a central partition wall. When enlarging the upper right bench, proceed in sections of 2-3m until the entire upper right bench is enlarged.

[0074] Step 2: Expand the excavation of the upper left step. Expand the upper left step in sections of 2-3m, and the upper left step should be carried out 15m later than the upper right step.

[0075] Step 3: Excavation of the middle step. The right middle step is excavated 15m later than the left upper step. At the same time, vertical and horizontal supports are set on the left side of the right middle step during the widening excavation. The left middle step is excavated 15m after the left upper step.

[0076] Step 4: Excavation of the lower steps. Before excavation, remove the vertical and horizontal supports in sections of 2-3m. The lower right step is excavated 15m later than the middle right step, and the lower left step is excavated 15m later than the middle left step.

[0077] Step 5: Construct the inverted arch. The initial support of the inverted arch will be completed 2-3 days later than the initial support of the lower left step.

[0078] To ensure overall support, in addition to the invert arch, anchor pipes were added to each steel frame after the excavation of each section was completed. Additionally, large arch feet were added to each steel frame on the upper step to prevent settlement. Anchor cable support was eliminated during the excavation process, effectively reducing construction time.

[0079] During tunnel excavation, it is necessary to monitor and measure both the new and existing tunnels, and adjust the corresponding construction based on the measurement results. If necessary, temporary steel frame support is installed within 10m of the existing lining adjacent to the excavation site.

[0080] Due to the presence of multiple working faces, the amount of slag generated is large. To reduce slag discharge pressure and prevent delays in construction progress, a reverse-engineering working face is constructed on each construction channel to serve as a temporary slag storage point. Positioning monitoring equipment and traffic lights are installed within the tunnel complex to ensure smooth transportation.

[0081] To ensure dust control and cooling within the tunnel complex, water mist dust suppression devices are installed on the excavation equipment. Fog cannons can be set up at appropriate locations near the tunnel face for secondary dust suppression. At the same time, bag filters are installed for thorough dust suppression, and temporary drainage ditches are laid to collect and promptly pump out construction water.

[0082] In summer, the temperature inside the tunnel is high, and the construction machinery and equipment have high power and long operating time, generating a lot of heat. In addition, the space inside the tunnel is limited and the air circulation is poor. Relying solely on ventilation and cooling is not enough to meet the requirements of a suitable environment inside the tunnel, which is not conducive to the construction of personnel and equipment. Therefore, the site is equipped with a tunnel-specific skid-mounted water-cooled unit TSWCC-630H for cooling.

Claims

1. A ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel, characterized in that, The multi-track tunnel group includes the existing first tunnel (1), second tunnel (2), and the third tunnel (3), fourth tunnel (4), and fifth tunnel (5) that need to be constructed. The third tunnel (3) is a new passage tunnel after the second tunnel (2) is abandoned at the end near the tunnel entrance. The fourth tunnel (4) overlaps with the second tunnel (2) at the end near the tunnel entrance. The first tunnel (1), third tunnel (3), and fourth tunnel (4) are set up side by side. The tunnel entrance of the fifth tunnel (5) is located on the side of the fourth tunnel (4) away from the third tunnel (3), and the end of the fifth tunnel (5) away from the tunnel entrance merges into the second tunnel (2). The tunnel entrance of the second tunnel (2) is located at the end of the second tunnel (3). Between the third tunnel (3) and the fourth tunnel (4); the multi-line tunnel is provided with a first construction passage (6), a second construction passage (7), a third construction passage (8) and a fourth construction passage (9) in sequence along the tunnel entrance, and the first construction passage (6), the second construction passage (7) and the third construction passage (8) are all in the overlapping section between the fourth tunnel (4) and the second tunnel (2), wherein the first construction passage (6), the second construction passage (7) and the third construction passage (8) are all synchronously connected to the second tunnel (2), the third tunnel (3), the fourth tunnel (4) and the fifth tunnel (5), and the fourth construction passage (9) is connected to the second tunnel (2) and the fourth tunnel (4); The third tunnel (3) has a fifth working face, a first working face, a second working face and a third working face in sequence from the tunnel entrance. The fourth tunnel (4) has a seventh working face and a fourth working face in sequence from the tunnel entrance. The fifth tunnel (5) has a sixth working face from the tunnel entrance. The first working face is connected to the first construction passage, the second working face is connected to the second construction passage, the third working face is connected to the third construction passage, and the fourth working face is connected to the fourth construction passage. The ventilation arrangement structure includes several forced-in fans, several jet fans, and several air-blocking curtains. The forced-in fans achieve ventilation of the corresponding working face through corresponding air channels. The jet fans are set at the intersections or turning points between tunnels. The air-blocking curtains are set at the intersections between the second tunnel and the other tunnels.

2. The ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel as described in claim 1, characterized in that: The ventilation duct includes four stages of ventilation ducts. The first stage ventilation duct is used for ventilation during the construction of the third tunnel (3), the fourth tunnel (4), and the fifth tunnel (5) after the construction of each construction channel is completed. It includes a first air duct (12), a second air duct (13), and a third air duct (14) that are respectively connected to a forced-in fan. The first air duct (12) is set as a duct extending along the fifth tunnel (5) to the sixth working face. At the same time, the first air duct (12) is connected in parallel with a duct that passes through the first construction channel (6) and extends to the first working face. The second air duct (13) is set as a duct that passes through the fourth construction channel (9) from the tunnel entrance of the second tunnel (2) and extends to the fourth working face. At the same time, the second air duct (13) is connected in parallel with a duct that passes through the third construction channel (8) and extends to the third working face. The third air duct (14) is set as a duct that extends from the tunnel entrance of the second tunnel (2) to the second working face. The second-stage ventilation duct is used to achieve ventilation during the construction of the third tunnel (3), fourth tunnel (4), and fifth tunnel (5) after the backfilling of the second tunnel (2) near the tunnel entrance. It includes the fourth ventilation duct (15), the fifth ventilation duct (16), the sixth ventilation duct (17), the seventh ventilation duct (18), and the eighth ventilation duct (19), which are respectively connected to the forced draft fan. The fourth ventilation duct (15) is a duct extending along the fifth tunnel (5) to the sixth working face. At the same time, the fourth ventilation duct (15) is connected in parallel with a duct that passes through the first construction passage (6) and extends to the first working face. The fifth ventilation duct (16) is connected in parallel with a duct that passes through the first construction passage (6) and extends to the first working face. 6) The ventilation duct extends from the tunnel entrance of the fifth tunnel (5) through the first construction passage (6) and the fourth construction passage (9) to the fourth working face. At the same time, the fifth ventilation duct (16) is connected in parallel at the third construction passage (8) to the ventilation duct that extends from the third construction passage (8) to the third working face. The sixth ventilation duct (17) extends from the tunnel entrance of the fifth tunnel through the first construction passage (6) to the second working face. The seventh ventilation duct (18) extends from the tunnel entrance of the fourth tunnel (4) to the seventh working face. The eighth ventilation duct (19) extends from the tunnel entrance of the third tunnel (3) to the fifth working face. The third-stage ventilation duct is used for ventilation during the construction of the fourth tunnel (4) and the fifth tunnel (5) after multiple working faces are connected on the third tunnel (3) and the sixth working face is located on the side away from the tunnel entrance of the second cross passage. It includes the ninth ventilation duct (20), the tenth ventilation duct (21) and the eleventh ventilation duct (22) which are respectively connected to the forced-in fan. The ninth ventilation duct (20) is a duct that extends along the fifth tunnel (5) to the sixth working face. The tenth ventilation duct (21) is a duct that extends from the tunnel entrance of the fifth tunnel (5) through the second construction passage (7) and the fourth construction passage (9) to the fourth working face. The eleventh ventilation duct (22) is a duct that extends along the fourth tunnel (4) to the seventh working face. The fourth stage is used for ventilation during the construction of the fourth tunnel after the fifth tunnel is completed. It includes the twelfth ventilation duct (23) and the thirteenth ventilation duct (24) which are respectively connected to the forced ventilation fan. The forced ventilation fan of the twelfth ventilation duct (23) is set at the cross section of the fifth tunnel. The twelfth ventilation duct (23) is a duct that is connected to the corresponding forced ventilation fan and extends to the fourth working face after passing through the third construction channel (8) and the fourth construction channel (9). The thirteenth ventilation duct (24) is a duct that extends along the fourth tunnel (4) to the seventh working face.

3. The ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel as described in claim 2, characterized in that: The forced ventilation fans in different stages can be reused, and the forced ventilation fans located outside the tunnel are set near the fifth tunnel (5).

4. The ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel as described in claim 2, characterized in that: In the first stage, the third ventilation duct (14) is connected in parallel with the second construction passage (7) and extends to the side of the sixth working face after passing through the second construction passage (7); in the second stage, the sixth ventilation duct (17) is connected in parallel with the second construction passage (7) and extends to the side of the sixth working face after passing through the second construction passage (7); in the third stage, an eighth working face connected to the third construction passage is provided in the fifth tunnel, and a fourteenth ventilation duct (25) is also provided. The fourteenth ventilation duct (25) is a ventilation duct that extends from the tunnel entrance of the fifth tunnel (5) through the second construction passage (7) and the third construction passage (8) to the eighth working face.

5. The ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel as described in claim 1, characterized in that: The second tunnel (2) is provided with a fifth construction passage (10) connected to the fourth tunnel (4) at one end away from the tunnel entrance. The fourth tunnel (4) is provided with a ninth working face for construction through the fifth construction passage (10). The second tunnel (2) is provided with a tenth working face for construction towards the third tunnel (3) at one end away from the tunnel entrance. The ventilation of the ninth working face and the tenth working face is achieved by ventilation components provided in the second tunnel (2).

6. The ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel as described in claim 5, characterized in that: The ventilation assembly includes a fan frame, a door and a curtain installed in the second tunnel (2). A forced-in fan is installed outside the door. The other end of the forced-in fan is connected to the outside through the sixth construction channel (11) and the construction inclined shaft on the side closest to the tunnel entrance of the fourth tunnel. The sixth construction channel (11) is used to connect the construction inclined shaft with the end of the second tunnel (2) away from the tunnel entrance.

7. The ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel as described in claim 1, characterized in that: The interval between the first construction passage (6), the second construction passage (7), and the third construction passage (8) is between 200 and 300 m.

8. The ventilation arrangement structure for constructing a group of tunnels with small clearance next to an existing tunnel as described in claim 1, characterized in that: The distance between adjacent jet fans is between 400-500m.

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