Ventilation arrangement structure of small-spacing tunnel near existing tunnel group construction

Abstract

The application discloses a ventilation arrangement structure for small-distance tunnel construction near existing tunnel groups, comprising a plurality of pressure-inlet fans, a plurality of jet fans and a plurality of air isolation curtains, the pressure-inlet fans realize ventilation of corresponding working surfaces through corresponding air channels, the jet fans are arranged at intersections or turning parts between tunnels, and the air isolation curtains are arranged at intersection positions between a second tunnel and the rest of the tunnels. For the small-distance hole groups near the existing line and multiple working surfaces, the pressure-inlet fans and the air channels corresponding to each working surface are changed along with the construction progress, ventilation of each working surface is realized, and the overall ventilation effect is ensured; the jet fans are arranged at the intersections or turning parts of the tunnels, used for ensuring the discharge of dirty air in the tunnels, and the air isolation curtains are arranged for blocking the dirty air, so that the ventilation effect is avoided from being affected by mutual influence.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ventilation technology in railway tunnel group construction, and particularly relates to a ventilation arrangement structure for small-distance tunnel construction near existing tunnel group. BACKGROUND

[0002] In the process of tunnel construction, fresh air is usually supplemented and the temperature in the tunnel is lowered by setting a ventilation structure. The ventilation effect directly determines the health and work efficiency of construction workers. In the past, tunnel construction rarely involved the case of simultaneous construction of existing lines and newly-built multi-tunnel small-distance parallel construction. In this construction, the working surface in the tunnel is large, and the construction personnel, mechanical equipment and vehicles are concentrated in the tunnel, so the process conversion is complex. Therefore, a ventilation arrangement structure is needed to ensure that the multiple working surfaces in the tunnel have continuous fresh air. SUMMARY

[0003] The present application proposes a ventilation arrangement structure for small-distance tunnel construction near existing tunnel group, to ensure ventilation of multiple working surfaces during small-distance tunnel construction near existing tunnel group.

[0004] To this end, the technical scheme adopted by the present application is as follows: a ventilation arrangement structure for small-distance tunnel construction near existing tunnel group, the multi-line tunnel group includes existing first tunnel, second tunnel and third tunnel, fourth tunnel and fifth tunnel that need to be constructed, wherein the third tunnel is a new passing tunnel abandoned at one end of the second tunnel near the tunnel portal, the fourth tunnel overlaps with the second tunnel at one end near the tunnel portal, the first tunnel, the third tunnel and the fourth tunnel are arranged side by side, the tunnel portal 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 the tunnel portal is connected to the second tunnel, and the tunnel portal of the second tunnel is located between the third tunnel and the fourth tunnel; first construction passage, second construction passage, third construction passage and fourth construction passage are sequentially arranged in the multi-line tunnel along the tunnel portal, and the first construction passage, the second construction passage and the third construction passage are all in the partially overlapping section of the fourth tunnel and the second tunnel, wherein the first construction passage, the second construction passage and the third construction passage are synchronously connected to the second tunnel, the third tunnel, the fourth tunnel and the fifth tunnel, and the fourth construction passage is connected to the second tunnel and the fourth tunnel;

[0005] The fifth working surface, the first working surface, the second working surface and the third working surface are sequentially arranged in the third tunnel from the tunnel portal inwardly, the seventh working surface and the fourth working surface are sequentially arranged in the fourth tunnel from the tunnel portal inwardly, the sixth working surface is arranged in the fifth tunnel from the tunnel portal inwardly, the first working surface is connected to the first construction passage, the second working surface is connected to the second construction passage, the third working surface is connected to the third construction passage, and the fourth working surface is connected to the fourth construction passage;

[0006] The ventilation arrangement comprises several push-in fans, several jet fans and several air curtains, the push-in fans ventilate corresponding working surfaces through corresponding air channels, the jet fans are arranged at intersections or turning positions between tunnels, and the air curtains are arranged at intersection positions between the second tunnel and the rest of the tunnels.

[0007] As a preferred solution in the above solution, the air channel comprises four-stage air channels, wherein the first-stage air channel is used for ventilation when the third tunnel, the fourth tunnel and the fifth tunnel are under construction after the completion of construction of each construction channel, and comprises a first air duct, a second air duct and a third air duct which are in communication with the push-in fans respectively, the first air duct is arranged as an air pipe extending along the fifth tunnel to the sixth working surface, and the first air duct is provided with an air pipe extending to the first working surface through the first construction channel in parallel at the first construction channel, the second air duct is arranged as an air pipe extending to the fourth working surface through the fourth construction channel from the tunnel opening of the second tunnel, and the second air duct is provided with an air pipe extending to the third working surface through the third construction channel in parallel at the third construction channel, and the third air duct is arranged as an air pipe extending to the second working surface from the tunnel opening of the second tunnel;

[0008] The second-stage air channel is used for ventilation when the third tunnel, the fourth tunnel and the fifth tunnel are under construction after the backfilling of the side of the second tunnel close to the tunnel opening, and comprises a fourth air duct, a fifth air duct, a sixth air duct, a seventh air duct and an eighth air duct which are in communication with the push-in fans respectively, the fourth air duct is an air pipe extending along the fifth tunnel to the sixth working surface, and the fourth air duct is provided with an air pipe extending to the first working surface through the first construction channel in parallel at the first construction channel, the fifth air duct is an air pipe extending to the fourth working surface through the first construction channel and the fourth construction channel from the tunnel opening of the fifth tunnel, and the fifth air duct is provided with an air pipe extending to the third working surface through the third construction channel in parallel at the third construction channel, the sixth air duct is an air pipe extending to the second working surface through the first construction channel from the tunnel opening of the fifth tunnel, the seventh air duct is an air pipe extending to the seventh working surface from the tunnel opening of the fourth tunnel, and the eighth air duct is an air pipe extending to the fifth working surface from the tunnel opening of the third tunnel;

[0009] The third-stage air channel is used for ventilation when the fourth tunnel and the fifth tunnel are under construction after the penetration of multiple working surfaces of the third tunnel and the sixth working surface is located on the side of the second cross channel away from the tunnel opening, and comprises a ninth air duct, a tenth air duct and an eleventh air duct which are in communication with the push-in fans respectively, the ninth air duct is an air pipe extending along the fifth tunnel to the sixth working surface, the tenth air duct is an air pipe extending to the fourth working surface through the second construction channel and the fourth construction channel from the tunnel opening of the fifth tunnel, and the eleventh air duct is an air pipe extending along the fourth tunnel to the seventh working surface;

[0010] The fourth stage is used for ventilation during the fourth tunnel construction after the fifth tunnel is completed, comprising a twelfth air duct and a thirteenth air duct respectively connected with the forced air fans, the forced air fan of the twelfth air duct is arranged at the cross section position of the fifth tunnel, the twelfth air duct is an air pipe connected with the corresponding forced air fan and extending to the fourth working surface through the third construction channel and the fourth construction channel, and the thirteenth air duct is an air pipe extending to the seventh working surface along the fourth tunnel.

[0011] Further preferably, the forced air fans in different stages can be reused, and the forced air fan arranged outside the tunnel is arranged close to the position of the fifth tunnel.

[0012] Further preferably, in the first stage, the third air duct is connected in parallel with an air pipe extending to the opposite side of the sixth working surface through the second construction channel at the second construction channel; in the second stage, the sixth air duct is connected in parallel with an air pipe extending to the opposite side of the sixth working surface through the second construction channel at the second construction channel, and in the third stage, the eighth working surface connected with the third construction channel is arranged in the fifth tunnel, and further comprising a fourteenth air duct, which is an air pipe extending to the eighth working surface through the tunnel portal of the fifth tunnel, the second construction channel and the third construction channel.

[0013] Further preferably, the second tunnel is provided with a fifth construction channel connected with the fourth tunnel at the end away from the tunnel portal, the fourth tunnel is provided with a ninth working surface constructed through the fifth construction channel, the second tunnel is provided with a tenth working surface facing the third tunnel construction at the end away from the tunnel portal, and the ventilation of the ninth working surface and the tenth working surface is realized by the ventilation assembly arranged in the second tunnel.

[0014] Further preferably, the ventilation assembly comprises a fan rack, an air door and an air curtain arranged in the second tunnel, the air door is equipped with two forced air fans, the other end of the forced air fan is connected with the outside through the sixth construction channel and the construction inclined shaft closest to the tunnel portal on the side of the fourth tunnel, and the sixth construction channel is used for connecting the construction inclined shaft with the end of the second tunnel away from the tunnel portal.

[0015] Further preferably, the interval between the first construction channel, the second construction channel and the third construction channel is between 200-300m.

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

[0017] The beneficial effects of the present application: For the small-pitch hole group near the existing line, the pressure-in type fan and the air channel corresponding to each working face are arranged, and the air channel changes with the construction progress, realizing the ventilation of each working face, so as to ensure the overall ventilation effect; The jet fan is arranged at the intersection or turning part of the tunnel, which is used to ensure the exhaust of the dirty air in the tunnel, and the air curtain is arranged to block the dirty air to avoid the influence of the ventilation effect. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a schematic diagram of the position of the multi-line tunnel in the present application.

[0019] Figure 2 The figure is a schematic diagram of the position of the multi-line tunnel in the present application. Figure 1 The figure is a schematic diagram of the position of the multi-line tunnel in the present application.

[0020] Figure 3 The figure is a schematic diagram of the position of the multi-line tunnel in the present application.

[0021] Figure 4 The figure is a schematic diagram of the position of the multi-line tunnel in the present application.

[0022] Figure 5 The figure is a schematic diagram of the position of the multi-line tunnel in the present application.

[0023] Figure 6 The figure is a schematic diagram of the position of the multi-line tunnel in the present application.

[0024] Figure 7 The figure is a schematic diagram of the position of the multi-line tunnel in the present application.

[0025] Figure 8 The figure is a schematic diagram of the position of the multi-line tunnel in the present application.

[0026] Reference signs: first tunnel-1, second tunnel-2, third tunnel-3, fourth tunnel-4, fifth tunnel-5, first construction channel-6, second construction channel-7, third construction channel-8, fourth construction channel-9, fifth construction channel-10, sixth construction channel-11, first air duct-12, second air duct-13 and third air duct-14, fourth air duct-15, fifth air duct-16, sixth air duct-17, seventh air duct-18, ninth air duct-20, tenth air duct-21, eleventh air duct-22, twelfth air duct-23, thirteenth air duct-24, and fourteenth air duct-25. DETAILED DESCRIPTION

[0027] The present application will be further described below by examples and in conjunction with the drawings:

[0028] As shown in the drawings, a ventilation arrangement structure for constructing a small-pitch tunnel near an existing tunnel group, as shown in the drawings, Figures 1-8 and Figure 1 and Figure 2As shown, the multi-line tunnel is composed of the existing first tunnel 1, second tunnel 2 and the third tunnel 3, fourth tunnel 4 and fifth tunnel 5 which need to be constructed. Among them, the first tunnel, the third tunnel and the fourth tunnel are arranged side by side, the tunnel entrance of the second tunnel is located between the third tunnel and the fourth tunnel, the tunnel entrance of the fifth tunnel 4 is located on the side of the fourth tunnel 4 away from the third tunnel 3, and the end of the fifth tunnel away from the tunnel entrance is connected to the merging position of the second tunnel and the third tunnel, that is, the fifth tunnel is connected to the second tunnel in the straight tunnel, and the adjacent distance between the two is small. The fourth tunnel and the second tunnel overlap at the end close to the tunnel entrance, and the third tunnel is a new passing tunnel after the end of the second tunnel close to the tunnel entrance is abandoned, that is, the entrance section of the second tunnel and the entrance section of the fourth tunnel partially overlap, so the entrance section of the second tunnel needs to be abandoned.

[0029] In order to speed up the construction, ensure the construction progress, and reduce the downtime, the tunnel group is provided with the first construction passage 6, the second construction passage 7, the third construction passage 8 and the fourth construction passage 9 in turn along the tunnel entrance. Preferably, the interval between the first construction passage, the second construction passage and the third construction passage is between 200-300m, and the first construction passage, the second construction passage and the third construction passage are all in the partially overlapping section of the fourth tunnel and the second tunnel, wherein the first construction passage, the second construction passage and the third construction passage are all connected to the second tunnel, the third tunnel, the fourth tunnel and the fifth tunnel synchronously, and the fourth construction passage is connected to the second tunnel and the fourth tunnel.

[0030] During the entire construction process, multiple working faces are provided in the tunnel group, specifically: the tenth working face is provided at the end of the second tunnel away from the tunnel entrance for construction towards the third tunnel. The fifth working face, the first working face, the second working face, the third working face are provided in the third tunnel in turn from the tunnel entrance. The seventh working face and the fourth working face are provided in the fourth tunnel in turn from the tunnel entrance, and the ninth working face is provided in the fourth tunnel for construction through the fifth construction passage. The sixth working face is provided in the fifth tunnel 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.

[0031] In order to speed up the penetration of the fifth tunnel, the eighth working face is further provided in the fifth tunnel for construction through the third construction passage to the merging position of the fifth tunnel and the third tunnel. The fifth construction passage 10 is provided at the end of the second tunnel away from the tunnel entrance for connection with the fourth tunnel. Correspondingly, the ninth working face is provided in the fourth tunnel for construction through the fifth construction passage, and the tenth working face is provided at the end of the second tunnel away from the tunnel entrance for construction towards the third tunnel. The ventilation of the ninth working face and the tenth working face is realized through the ventilation assembly provided in the second tunnel. The first working face to the tenth working face are as shown in the figure. Figure 3The circled numbers in the diagram represent the corresponding working surfaces.

[0032] The ventilation arrangement structure includes several forced-in fans, several jet fans, and several air-blocking curtains. The forced-in 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.

[0033] 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 4 As shown, ventilation during the construction of the third, fourth, and fifth tunnels after the completion of construction in each construction passage 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 ventilation duct. 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.

[0034] like Figure 5As 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.

[0035] like Figure 6 As 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] like Figure 3 As shown, the construction method for a multi-track tunnel group includes the following steps:

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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:

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] like Figure 8As shown in the figure, the circled numbers indicate the excavation sequence. The excavation of the large-span VK2 section includes the following steps:

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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 tunnels with small clearances during construction adjacent to existing tunnel groups, 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 on the side of the third tunnel (3). Between tunnel (3) and 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. 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 at the first construction channel (6) 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 (4) 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 at the third construction channel (8) 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. 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).

2. The ventilation arrangement structure for tunnels with small clearances near existing tunnel groups as described in claim 1, 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).

3. The ventilation arrangement structure for tunnels with small clearances during construction adjacent to existing tunnel groups as described in claim 1, 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.

4. The ventilation arrangement structure for tunnels with small clearances near existing tunnel groups as described in claim 1, 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.

5. The ventilation arrangement structure for tunnels with small clearances near existing tunnel groups 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.

6. The ventilation arrangement structure for tunnels with small clearances near existing tunnel groups as described in claim 1, characterized in that: The distance between adjacent jet fans is between 400-500m.

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