Ventilation arrangement structure for constructing small-distance tunnel close to existing tunnel group

Abstract

The ventilation arrangement structure comprises a plurality of press-in type draught fans, a plurality of jet fans and a plurality of air separation curtains, the press-in type draught fans achieve ventilation of corresponding working faces through corresponding air channels, the jet fans are arranged at intersections or turning parts between the tunnels, and the air separation curtains are arranged on the intersections or turning parts. And the air separation curtain is arranged at the intersection position between the second tunnel and the other tunnels. Aiming at a plurality of working surfaces of a small-clear-distance cave group close to the existing line, the ventilation of each working surface is realized through a press-in type fan and an air channel corresponding to each working surface and the air channel is changed along with the construction progress, so that the overall ventilation effect is ensured; the jet fan is arranged at the crossed or turning part of the tunnel and used for ensuring discharge of dirty air in the tunnel, and meanwhile, the air separation curtain is arranged and used for blocking the dirty air, so that the ventilation effect is prevented from being influenced by channeling of the dirty air.

Description

Technical Field

[0001] The present invention belongs to the technical field of ventilation in the construction of railway tunnel groups, and particularly relates to a ventilation layout structure for a small clear distance tunnel during the construction adjacent to an existing tunnel group. Background Art

[0002] During the tunnel construction process, fresh air is usually supplemented into the tunnel and the temperature in the tunnel is reduced by setting up a ventilation structure. The quality of the ventilation effect directly determines the health and working efficiency of construction workers. In the past, tunnel construction rarely involved the situation of simultaneous parallel construction of an existing line and multiple newly-built tunnels with a small clear distance. In this construction, due to the large number of working faces in the tunnel, and the construction personnel, mechanical equipment and vehicles in the tunnel are concentrated in the tunnel, and the process conversion is complex, so a ventilation layout structure is needed to ensure that there is continuous fresh air in multiple working faces in the tunnel. Summary of the Invention

[0003] The present invention intends to propose a ventilation layout structure for a small clear distance tunnel during the construction adjacent to an existing tunnel group, so as to ensure the ventilation of multiple working faces during the construction of a small clear distance tunnel group adjacent to an existing tunnel.

[0004] Therefore, the technical solution adopted by the present invention is as follows: A ventilation layout structure for a small clear distance tunnel during the construction adjacent to an existing tunnel group. The multi-line tunnel group includes the existing First Tunnel, Second Tunnel and the Third Tunnel, Fourth Tunnel, Fifth Tunnel to be constructed. Among them, the Third Tunnel is a new traffic tunnel after one end of the Second Tunnel near the tunnel entrance is abandoned. The Fourth Tunnel overlaps with the Second Tunnel at one end near the tunnel entrance. The First Tunnel, Third Tunnel, and Fourth Tunnel are arranged side by side. The tunnel entrance of the Fifth Tunnel is located on the side of the Fourth Tunnel far from the Third Tunnel, and one end of the Fifth Tunnel far from the tunnel entrance merges into the Second Tunnel. The tunnel entrance of the Second Tunnel is located between the Third Tunnel and the Fourth Tunnel. Inside the multi-line tunnel, a First Construction Passage, Second Construction Passage, Third Construction Passage, and Fourth Construction Passage are successively arranged inward along the tunnel entrance. And the First Construction Passage, Second Construction Passage, and Third Construction Passage are all within the overlapping section of the Fourth Tunnel and the Second Tunnel. Among them, the First Construction Passage, Second Construction Passage, and Third Construction Passage are all synchronously connected to the Second Tunnel, Third Tunnel, Fourth Tunnel, and Fifth Tunnel. The Fourth Construction Passage is connected to the Second Tunnel and the Fourth Tunnel.

[0005] At the Third Tunnel, a Fifth Working Face, First Working Face, Second Working Face, and Third Working Face are successively arranged inward from the tunnel entrance. At the Fourth Tunnel, a Seventh Working Face and a Fourth Working Face are successively arranged inward from the tunnel entrance. At the Fifth Tunnel, a Sixth Working Face is arranged inward 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.

[0006] The ventilation layout structure includes a number of forced draft fans, a number of jet fans and a number of air separation curtains. The forced draft fans ventilate the corresponding working faces through the corresponding air channels. The jet fans are arranged at the intersections or turning parts between the tunnels. The air separation curtains are arranged at the intersection positions between the second tunnel and the other tunnels.

[0007] As a preference in the above solution, the air channel includes air channels in four stages. Among them, the air channel in the first stage is used for ventilation during the construction of the third tunnel, the fourth tunnel and the fifth tunnel after the construction of each construction channel is completed, and includes a first air duct, a second air duct and a third air duct respectively connected to the forced draft fans. The first air duct is arranged as an air 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 with an air duct extending to the first working face after passing through the first construction channel. The second air duct is arranged as an air duct extending from the tunnel entrance of the second tunnel through the fourth construction channel to the fourth working face. At the same time, the second air duct is connected in parallel at the third construction channel with an air duct extending to the third working face after passing through the third construction channel. The third air duct is arranged as an air duct extending from the tunnel entrance of the second tunnel to the second working face;

[0008] The air channel in the second stage is used for ventilation during the construction of the third tunnel, the fourth tunnel and the fifth tunnel after the backfilling of the side of the second tunnel close to the tunnel entrance is completed, and includes a fourth air duct, a fifth air duct, a sixth air duct, a seventh air duct and an eighth air duct respectively connected to the forced draft fans. The fourth air duct is an air duct extending along the fifth tunnel to the sixth working face. At the same time, the fourth air duct is connected in parallel at the first construction channel with an air duct extending to the first working face after passing through the first construction channel. The fifth air duct is an air duct extending from the tunnel entrance of the fifth tunnel through the first construction channel and the fourth construction channel to the fourth working face. At the same time, the fifth air duct is connected in parallel at the third construction channel with an air duct extending to the third working face after passing through the third construction channel. The sixth air duct is an air duct extending from the tunnel entrance of the fifth tunnel through the first construction channel to the second working face. The seventh air duct is an air duct extending from the tunnel entrance of the fourth tunnel to the seventh working face. The eighth air duct is an air duct extending from the tunnel entrance of the third tunnel to the fifth working face;

[0009] The air channel in the third stage is used for ventilation during the construction of the fourth tunnel and the fifth tunnel after multiple working faces on the third tunnel are connected and the sixth working face is located on the side of the second cross-channel far from the tunnel entrance, and includes a ninth air duct, a tenth air duct and an eleventh air duct respectively connected to the forced draft fans. The ninth air duct is an air duct extending along the fifth tunnel to the sixth working face. The tenth air duct is an air duct extending from the tunnel entrance of the fifth tunnel through the second construction channel and the fourth construction channel to the fourth working face. The eleventh air duct is an air duct extending 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 penetrated, including the twelfth air duct and the thirteenth air duct respectively connected to the pressure-in fan. The pressure-in fan of the twelfth air duct is arranged at the span position of the fifth tunnel. The twelfth air duct is an air duct connected to the corresponding pressure-in fan and extends to the fourth working surface after passing through the third construction channel and the fourth construction channel. The thirteenth air duct is an air duct extending to the seventh working surface along the fourth tunnel.

[0011] It is further preferred that the pressure fans in different stages are reusable, and the pressure fans outside the tunnel are arranged near the fifth tunnel.

[0012] It is further preferred that, in the first stage, the third air duct is connected in parallel at the second construction channel with an air duct that passes through the second construction channel and extends to the side of the sixth working surface; in the second stage, the sixth air duct is connected in parallel at the second construction channel with an air duct that passes through the second construction channel and extends to the side of the sixth working surface; in the third stage, an eighth working surface connected to the third construction channel is provided in the fifth tunnel, and also includes a fourteenth air duct, which is an air duct that extends from the tunnel entrance of the fifth tunnel through the second construction channel and the third construction channel to the eighth working surface.

[0013] It is further preferred that a fifth construction channel connected to the fourth tunnel is provided at one end of the second tunnel away from the tunnel entrance, a ninth working surface constructed through the fifth construction channel is provided in the fourth tunnel, and a tenth working surface toward the third tunnel is provided at one end of the second tunnel away from the tunnel entrance, and ventilation of the ninth working surface and the tenth working surface is achieved through ventilation components provided in the second tunnel.

[0014] Further preferably, the ventilation assembly includes a fan rack, a damper and a wind curtain arranged in the second tunnel, and two pressure fans are provided outside the damper. The other end of the pressure fan is connected to the outside through the sixth construction channel and the construction inclined shaft on the side closest to the tunnel entrance on the fourth tunnel. 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 intervals between the first construction channel, the second construction channel and the third construction channel are between 200-300 m.

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

[0017] Advantages of the present invention: For a small clear distance tunnel group with multiple working faces near an existing line, through a forced draft fan and air ducts corresponding to each working face, and the air ducts change with the construction progress, ventilation of each working face is achieved, thereby ensuring the overall ventilation effect; jet fans are arranged at the intersection or turning part of the tunnel to ensure the discharge of polluted air in the tunnel. At the same time, air separation curtains are arranged to block the polluted air and prevent it from affecting the ventilation effect by cross-flow. Brief Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the position of a multi-line tunnel in the present invention.

[0019] Figure 2 is Figure 1 a schematic diagram of a medium cross-section.

[0020] Figure 3 It is a construction schematic diagram of a multi-line tunnel in the present invention.

[0021] Figure 4 It is a schematic diagram of the air duct in the first stage.

[0022] Figure 5 It is a schematic diagram of the air duct in the second stage.

[0023] Figure 6 It is a schematic diagram of the air duct in the third stage.

[0024] Figure 7 It is a schematic diagram of the air duct when the construction of the third tunnel is completed.

[0025] Figure 8 It is a construction schematic diagram of a large-span section in the multi-line tunnel of the present invention.

[0026] Reference numerals: First Tunnel - 1, Second Tunnel - 2, Third Tunnel - 3, Fourth Tunnel - 4, Fifth Tunnel - 5, First Construction Passage - 6, Second Construction Passage - 7, Third Construction Passage - 8, Fourth Construction Passage - 9, Fifth Construction Passage - 10, Sixth Construction Passage - 11, First Air Duct - 12, Second Air Duct - 13, 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, Fourteenth Air Duct - 25. Detailed Description of the Invention

[0027] The present invention will be further described below through embodiments in conjunction with the drawings:

[0028] As Figures 1-8 shown, a ventilation layout structure for a small clear distance tunnel constructed near an existing tunnel group, as Figure 1 and Figure 2As shown in the figure, the multi-line tunnel consists of the existing First Tunnel 1, Second Tunnel 2 and the Third Tunnel 3, Fourth Tunnel 4, and Fifth Tunnel 5 to be constructed. Among them, the First Tunnel, Third Tunnel, and 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 away from the Third Tunnel 3. The end of the Fifth Tunnel away from the tunnel entrance merges into the junction of the Second Tunnel and the Third Tunnel, that is, the main tunnel of the Fifth Tunnel merges with the Second Tunnel, and the adjacent distance between them is small. The Fourth Tunnel and the Second Tunnel overlap at one end near the tunnel entrance. The Third Tunnel is the new traffic tunnel after the abandonment of the entrance section of the Second Tunnel, that is, there is partial overlap between the entrance section of the Second Tunnel and the entrance section of the Fourth Tunnel. Therefore, the entrance section of the Second Tunnel needs to be abandoned.

[0029] To accelerate the construction, ensure the construction progress, and at the same time reduce the outage time, during the construction of this tunnel group, there are successively the First Construction Passage 6, Second Construction Passage 7, Third Construction Passage 8, and Fourth Construction Passage 9 from the tunnel entrance inward. Preferably, the intervals between the First Construction Passage, Second Construction Passage, and Third Construction Passage are between 200 - 300 m, and the First Construction Passage, Second Construction Passage, and Third Construction Passage are all within the overlapping section of the Fourth Tunnel and the Second Tunnel. Among them, the First Construction Passage, Second Construction Passage, and Third Construction Passage are all synchronously connected to the Second Tunnel, Third Tunnel, Fourth Tunnel, and Fifth Tunnel, and the Fourth Construction Passage is connected to the Second Tunnel and the Fourth Tunnel.

[0030] During the entire construction process, there are multiple working faces in the tunnel group. Specifically: there is a Tenth Working Face facing the Third Tunnel at the end of the Second Tunnel away from the tunnel entrance. Inside the Third Tunnel, there are successively the Fifth Working Face, First Working Face, Second Working Face, and Third Working Face from the tunnel entrance inward. Inside the Fourth Tunnel, there are successively the Seventh Working Face and Fourth Working Face from the tunnel entrance inward. At the same time, there is a Ninth Working Face in the Fourth Tunnel constructed through the Fifth Construction Passage. Inside the Fifth Tunnel, there is a Sixth Working Face from the tunnel entrance inward. 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] To accelerate the penetration of the Fifth Tunnel, there is also an Eighth Working Face in the Fifth Tunnel constructed through the Third Construction Tunnel towards the merging position of the Fifth Tunnel and the Third Tunnel. There is a Fifth Construction Passage 10 connecting the end of the Second Tunnel away from the tunnel entrance to the Fourth Tunnel. Correspondingly, there is a Ninth Working Face in the Fourth Tunnel constructed through the Fifth Construction Passage. There is a Tenth Working Face facing the Third Tunnel at the end of the Second Tunnel away from the tunnel entrance. The ventilation of the Ninth Working Face and the Tenth Working Face is achieved through the ventilation components arranged in the Second Tunnel. The First Working Face to the Tenth Working Face are as Figure 3The circled numbers shown, and the numbers are the corresponding working faces.

[0032] The ventilation layout structure includes a number of forced draft fans, a number of jet fans and a number of air separation curtains. The forced draft fans achieve ventilation for the corresponding working faces through the corresponding air channels. The jet fans are arranged at the intersections or turning parts between the tunnels, and the distance between adjacent jet fans is between 400 - 500 m. The air separation curtains are arranged at the intersection positions between the second tunnel and the other tunnels.

[0033] Among them, the air channels are set according to specific construction sections. Specifically, the air channels include air channels in four stages. Among them, the air channels in the first stage are as Figure 4 shown, and are used to achieve ventilation during the construction of the third tunnel, the fourth tunnel, and the fifth tunnel 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 the forced draft fans. The first air duct is set as an air duct that extends along the fifth tunnel to the sixth working face. At the same time, the first air duct is paralleled with an air duct that extends to the first working face after passing through the first construction channel at the first construction channel. The second air duct is set as an air duct that passes through the fourth construction channel from the tunnel entrance of the second tunnel and then extends to the fourth working face. At the same time, the second air duct is paralleled with an air duct that extends to the third working face after passing through the third construction channel at the third construction channel. The third air duct is set as an air duct that extends from the tunnel entrance of the second tunnel to the second working face. At the same time, to accelerate the penetration of the fifth tunnel from the tunnel entrance to the second construction channel, the third air duct is paralleled with an air duct that passes through the second construction channel and then extends to the opposite side of the sixth working face at the second construction channel.

[0034] As Figure 5As shown, the wind channel of the second stage is used to realize the ventilation during the construction of the third tunnel, the fourth tunnel and the fifth tunnel after the backfilling of the side near the tunnel entrance, and the section from the tunnel entrance of the fifth tunnel to the first construction channel has been completed, including the fourth wind channel 15, the fifth wind channel 16, the sixth wind channel 17, the seventh wind channel 18 and the eighth wind channel 19 respectively connected to the pressure-in fan. The fourth wind channel 15 is a wind duct extending from the fifth tunnel 5 to the sixth working surface, and the fourth wind channel 15 is connected in parallel with the wind duct extending from the first construction channel 6 to the first working surface at the first construction channel 6. The fifth wind channel 16 extends from the tunnel entrance of the fifth tunnel 5 to the fourth working surface through the first construction channel 6 and the fourth construction channel 9, and the fifth wind channel 16 is connected in parallel with the wind duct extending from the third construction channel 8 to the third working surface at the third construction channel 8. The seventh wind channel 18 is a wind duct extending from the tunnel entrance of the fourth tunnel 4 to the seventh working surface. The eighth wind channel 19 is a wind duct extending from the tunnel entrance of the third tunnel 3 to the fifth working surface. The sixth air duct 17 extends from the tunnel entrance of the fifth tunnel through the first construction channel 6 to the air duct of the second working surface. At the same time, in order to speed up the penetration of the fifth tunnel from the tunnel entrance to the second construction channel, the sixth air duct 17 is connected in parallel with the second construction channel 7 with an air duct that passes through the second construction channel 7 and extends to the side of the sixth working surface.

[0035] like Figure 6 As shown, the wind channel of the third stage is used to realize the connection of multiple working surfaces on the third tunnel. At the same time, the section from the tunnel entrance to the second construction channel of the fifth tunnel has been completed. The ventilation during the construction of the fourth tunnel and the fifth tunnel includes the ninth wind duct 20, the tenth wind duct 21, and the eleventh wind duct 22 respectively connected to the pressure-in fan. The wind duct of the ninth wind duct 20 is an air duct extending from the fifth tunnel 5 to the sixth working surface. The tenth wind duct 21 is an air duct extending from the tunnel entrance of the fifth tunnel 5 through the second construction channel 7 and the fourth construction channel 9 to the fourth working surface. The eleventh wind duct 22 is an air duct extending from the fourth tunnel 4 to the seventh working surface. In order to speed up the connection of the fifth tunnel, the fourteenth wind duct 25 is also included. The fourteenth wind duct 25 is an air duct extending from the tunnel entrance of the fifth tunnel 5 through the second construction channel 7 and the third construction channel 8 to the eighth working surface.

[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 connected, including the twelfth air duct 23 and the thirteenth air duct 24 respectively connected to the fans during the pressure injection, wherein the pressure injection fan of the twelfth air duct 23 is arranged at the span position of the fifth tunnel, and the twelfth air duct 23 is connected to the corresponding pressure injection fan and extends to the fourth working surface after passing through the third construction channel 8 and the fourth construction channel 9. The thirteenth air duct 24 is an air duct extending along the fourth tunnel 4 to the seventh working surface.

[0037] The forced draft fans in different stages can be reused, that is, the same forced draft fan can be connected to the air ducts in different stages. For example, the first air duct, the fourth air duct, and the ninth air duct are all supplied with air by the same forced draft fan. For the convenience of management, the forced draft fans located outside the tunnel are arranged adjacent to each other. Preferably, they are all arranged near the position of the fifth tunnel.

[0038] The ventilation component includes a fan frame, a damper, and an air isolation curtain arranged in the second tunnel. A forced draft fan is equipped outside the damper. The other end of the forced draft fan is connected to the outside through the sixth construction passage 11 and the construction inclined shaft on the side closest to the tunnel entrance on the fourth tunnel. The sixth construction passage is used to connect the construction inclined shaft with the end of the second tunnel far from the tunnel entrance.

[0039] Such as Figure 3 As shown, the construction method of the multi-line tunnel group includes the following steps:

[0040] The first step is the construction of the construction passage. Using the second tunnel, the first construction passage 6, the second construction passage 7, the third construction passage 8, and the fourth construction passage 9 are constructed synchronously inward along the tunnel entrance in sequence. Moreover, the first construction passage, the second construction passage, and the third construction passage are all within the overlapping section of the fourth tunnel and the second tunnel. Among them, the first construction passage, the second construction passage, and the third construction passage are all synchronously connected to the second tunnel, the third tunnel, the fourth tunnel, and the fifth tunnel. The fourth construction passage is connected to the second tunnel and the fourth tunnel. When constructing the construction passage, the fifth tunnel is simultaneously constructed inward from the tunnel entrance. At this time, the entry and exit of vehicles are all realized through the second tunnel.

[0041] The second step is the construction of the third tunnel and the fifth tunnel. After the construction between the connection of the fifth tunnel and the first construction passage and the tunnel entrance is completed, backfill the section between the connection of the second tunnel and the first construction passage and the tunnel entrance. And after the second construction passage is completed, construct the fifth tunnel towards the tunnel entrance direction through the second construction passage, so that the section from the intersection of the fifth tunnel and the second construction passage to the tunnel entrance is first penetrated, facilitating the passage of each construction passage through the fifth tunnel after the backfill of the tunnel entrance section of the second tunnel.

[0042] At the same time, after the fourth construction passage is completed, construct the fourth tunnel in the direction away from the tunnel entrance through the fourth construction passage, that is, construct inward through the fourth construction passage until it penetrates through to the main tunnel.

[0043] At the same time, after the first construction passage, the second construction passage, and the third construction passage are completed, construct the third tunnel inward through the first construction passage, the second construction passage, and the third construction passage respectively. Through the construction of multiple working faces, the opening to traffic of the third tunnel is accelerated.

[0044] Step 3: Driving through the Third Tunnel, Fourth Tunnel, and Fifth Tunnel. When the Third Tunnel is driven through the Third Construction Passage to connect with the Second Tunnel, backfill the section between the connection point of the Third Tunnel and the Second Tunnel and the connection point with the Fourth Construction Passage in the Second Tunnel.

[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, start driving the Third Tunnel inward from the tunnel entrance until the Third Tunnel is fully driven through. After the Third Tunnel is driven through, backfill the remaining part of the entrance section of the Second Tunnel.

[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, start driving the Fourth Tunnel inward from the tunnel entrance of the Fourth Tunnel until the construction of the Fourth Tunnel is completed, that is, it is connected to the main tunnel of the Fourth Tunnel.

[0047] After the construction between the position of the Second Construction Passage and the tunnel entrance in the Fifth Tunnel is completed, the Fifth Tunnel continues to be driven inward until it reaches the merging point of the Third Tunnel and the Second Tunnel.

[0048] To further accelerate the construction progress, the Fifth Construction Passage 10 is also constructed synchronously. The Fifth Construction Passage connects the far end of the Second Tunnel and the Fourth Tunnel away from the tunnel entrance, and the Fifth Construction Passage is located in the section of the Second Passage that does not need to be abandoned. After the construction of the Fifth Construction Passage is completed, use the Fifth Construction Passage to drive the Fourth Tunnel towards the tunnel entrance. To quickly enter the side of the Second Tunnel away from the tunnel entrance, a Sixth Construction Passage 11 connected to the Second Tunnel is provided at the construction inclined shaft closest to the entrance end on the Fourth Tunnel. To quickly achieve the penetration of the Fifth Tunnel, when constructing the inner side of the Second Construction Passage in the Fifth Tunnel, simultaneously drive the Fifth Tunnel towards the merging position of the Fifth Tunnel and the Third Tunnel through the Third Construction Passage.

[0049] In the construction of the new tunnels, mechanical excavation is used for the excavation and advancement of the Third Tunnel, Fourth Tunnel, and Fifth Tunnel. At the same time, when constructing the Third Tunnel, the invert and filling follow the excavation and advancement of the heading face, and except for the section between the connection point with the First Construction Passage and the tunnel entrance, the secondary lining construction of the rest is carried out after the Third Tunnel is connected to the Second Tunnel at the tunnel entrance. When constructing the Fifth Tunnel, except for the section between the connection point with the First Construction Passage and the tunnel entrance in the Fifth Tunnel, the secondary lining construction of the rest is carried out after the secondary lining of the Third Tunnel is completed with multiple working faces. When constructing the Fourth Tunnel, except for the section between the connection point with the First Construction Passage and the tunnel entrance in the Fourth Tunnel, the secondary lining construction of the rest is carried out after the Fourth Tunnel is connected to the main tunnel.

[0050] Since the second tunnel is a single-track tunnel and the fourth tunnel is a double-track tunnel, there will be a section of the second tunnel that is completely inside the fourth tunnel. When the second tunnel is completely within the contour of the fourth tunnel, no backfilling is required, but for the rest, backfilling is needed. During the backfilling of the second tunnel, at the overlapping part between the second tunnel and the third tunnel, the part outside the contour of the third tunnel is backfilled with concrete, and the part inside the contour of the third tunnel is backfilled with foamed lightweight soil. Between the position where the second tunnel and the third tunnel start to overlap and the position where the second tunnel completely leaves the fourth tunnel, it is backfilled with a concrete retaining wall + foamed lightweight soil. Between the position where the second tunnel completely leaves the fourth tunnel and the position where the second tunnel is completely within the fourth tunnel, the part outside the contour of the fourth tunnel or the fourth construction access is backfilled with foamed lightweight soil, and the part inside the contour is backfilled with earth and rock. Between the position where the second tunnel starts to be completely within the fourth tunnel and the tunnel entrance of the second tunnel, the part outside the contour of the fourth tunnel is backfilled with concrete, and the part inside the contour is backfilled with earth and rock.

[0051] During the entire construction process, since the first tunnel is adjacent to the third tunnel and the first tunnel is an existing tunnel, to reduce the impact on the first tunnel during the construction of the third tunnel, before the construction of the third tunnel, it is necessary to use the non-operating time of the first tunnel to carry out corrugated plate lining and disease treatment for the third tunnel.

[0052] This construction method has been specifically implemented. At the tunnel entrance, the distance between the first tunnel and the third tunnel is 5.94m, the distance between the third tunnel and the second tunnel is 0.54m, the distance between the second tunnel and the fourth tunnel is 0.75m, and the distance between the fourth tunnel and the fifth tunnel is 2.14m. The distances between the tunnel entrance, the first construction access, the second construction access, and the third construction access adjacent to each other are between 200 - 300m.

[0053] When the first tunnel is first excavated and then the second tunnel is rerouted and incorporated into the first tunnel, the first tunnel needs to be out of service for 12 months in the early stage, and the second tunnel needs to be out of service for 21 months in the later stage, with a total outage of 33 months. After adopting this construction method, the first tunnel does not need to be modified, and only the second tunnel needs to be out of service for 9.4 months. When the third tunnel is completed, although the new tunnel is not completely finished, the third tunnel can be opened to traffic, that is, the existing line can be opened to traffic. Therefore, the overall outage time is less, reducing the impact on travel.

[0054] The overall construction length of the third tunnel is 1245 m. Among them, 966 m near one side of the tunnel entrance is constructed from the tunnel entrance inward, and the other 264 m is the parallel section of the fifth tunnel, the second tunnel and the third tunnel. It is constructed from the second tunnel towards the tunnel entrance side. This section is a turnout and large-span section, which is divided into four sections according to the section span, namely: the switch machine section, the Vb double-track turnout section, the second largest span VK1 section and the large span VK2 section. Among them, the switch machine section is the section where turnouts are set, and the large span VK2 section is where the two lines are completely separated. Moreover, the spans of the switch machine section, the Vb double-track turnout section, the second largest span VK1 section and the large span VK2 section increase in sequence. There is also a section of the third tunnel marked as Vb-D turnout single track before the large span VK2 section. There are four sections with different spans, and they are excavated in sections to reduce the disturbance of the stress change caused by the too large change of the section to the rock stratum, so as to effectively reduce the setting of time-consuming supports such as anchor cables and facilitate the reduction of the excavation construction time.

[0055] The switch machine section, the Vb double-track turnout section, the second largest span VK1 section and the Vb-D turnout single track are all constructed by the bench method, and the large span VK2 section is constructed by the center diaphragm CD method; for the second lining of the second largest span VK1 section and the large span VK2 section, a mobile full hall formwork is used for construction, for the Vb double-track turnout section, a second lining formwork trolley is used for construction, and for the switch machine section and the Vb-D turnout single track, a second lining formwork trolley with a set of trolley skeletons is used for construction. Among them, the end face spans of the switch machine section, the Vb double-track turnout 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, it is necessary to carry out excavation for this. The excavation sequence of the turnout and large-span section is the Vb double-track turnout section, the second largest span VK1 section, the large span VK2 section, the Vb-D turnout single track, and the switch machine section.

[0056] The excavation of the Vb double-track turnout section, the second largest span VK1 section and the switch machine section includes the following steps:

[0057] The first step: Under the advanced support of the previous cycle, demolish the existing tunnel arch lining of the upper bench, and then excavate the upper bench on the left and right sides, and construct the initial support of the upper bench.

[0058] The second step: Demolish the existing tunnel side wall and invert of the lower part, and then excavate the middle and lower benches on the left and right sides, and construct the initial support of the middle and lower benches.

[0059] The third step: Excavate the invert parts on the left and right sides, construct the initial invert support, and then successively construct the invert lining, side wall and arch lining.

[0060] During the construction process, the advance footage of each cycle of the upper bench is not more than two sets of arch frames, the advance footage of each cycle of the middle and lower benches is not more than three sets of arch frames, the excavation on the left and right sides is staggered by three sets of arch frames, and the invert is not more than five sets of arch frames in one cycle.

[0061] Such as Figure 8As shown in the figure, the circled numbers in the figure are the excavation sequence for enlargement. The enlargement of the large-span VK2 section includes the following steps:

[0062] The first step: Advance support conduits are constructed within the arch area of the existing tunnel, and then the upper right bench is excavated. Meanwhile, upper bench vertical struts are set at the left side position of the enlarged upper bench. The vertical struts are steel rigid frames, and concrete is sprayed on the vertical struts to be used as the middle partition wall. When excavating the upper right bench for enlargement, it is carried out in sections of 2 - 3 m until the excavation of the entire upper right bench is completed.

[0063] The second step: For the excavation of the upper left bench, the upper left bench is excavated in sections of 2 - 3 m, and the upper left bench lags behind the upper right bench by 15 m.

[0064] The third step: For the excavation of the middle bench, the right middle bench is excavated after lagging behind the upper left bench by 15 m. Meanwhile, middle bench vertical struts and cross struts are set at the left side position of the enlarged right middle bench. The left middle bench is carried out after the upper left bench is excavated by 15 m.

[0065] The fourth step: For the excavation of the lower bench, before excavation, the vertical struts and cross struts are removed in sections of 2 - 3 m. The lower right bench is excavated after lagging behind the right middle bench by 15 m, and the lower left bench is excavated after lagging behind the left middle bench by 15 m.

[0066] The fifth step: The invert is constructed. The initial support of the invert lags behind the initial support of the lower left bench by 2 - 3 days to complete.

[0067] To ensure the overall support, except for the invert, locking foot anchor pipes are added to each steel rigid frame after the enlargement of each part is completed. At the same time, large arch feet for preventing settlement are also added to each steel rigid frame of the upper bench. The support of the cable bolts is cancelled during the enlargement process, which can effectively reduce the construction time.

[0068] During the tunnel excavation process, it is necessary to monitor and measure the newly built tunnel and the existing tunnel, and adjust the corresponding construction according to the measurement results. When necessary, a temporary support of steel rigid frames is set within 10 m of the existing lining near the excavation.

[0069] Due to the existence of multiple working faces, the muck output is large. To reduce the muck discharge pressure and prevent the muck from affecting the construction progress, the working face of each construction channel is backfilled to serve as a temporary muck storage point. Positioning monitoring equipment and traffic lights for ensuring smooth transportation are set within the tunnel group.

[0070] To ensure dust removal and temperature reduction within the tunnel group, a water spray dust reduction device is configured for the excavation equipment, and a fog cannon can be set at a reasonable position near the heading face for secondary dust reduction by spraying mist. At the same time, a bag filter dust collector is installed for thorough dust reduction, and temporary intercepting and drainage ditches are arranged to collect and timely drain the construction water.

[0071] In summer, the temperature in the tunnel is high during operation. The construction machinery and equipment have high power, long operation hours, and generate a large amount of heat. Coupled with the limited space and poor air circulation in the tunnel, it is difficult to meet the requirements of a suitable environment in the tunnel only by ventilation and cooling, which is not conducive to construction such as personnel and equipment. A tunnel-specific skid-mounted water-cooled unit TSWCC-630H is equipped on-site for cooling.

Claims

1. A ventilation layout structure for a small clear distance tunnel constructed adjacent to an existing tunnel group, characterized in that The multi-line tunnel group includes the existing first tunnel (1), second tunnel (2), and the third tunnel (3), fourth tunnel (4), and fifth tunnel (5) to be constructed. Among them, the third tunnel (3) is a new traffic tunnel after one end of the second tunnel (2) near the tunnel entrance is abandoned. The fourth tunnel (4) overlaps with the second tunnel (2) at one end near the tunnel entrance. The first tunnel (1), third tunnel (3), and fourth tunnel (4) are arranged 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 one 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 between the third tunnel (3) and the fourth tunnel (4). Inside the multi-line tunnel, a first construction passage (6), a second construction passage (7), a third construction passage (8), and a fourth construction passage (9) are successively arranged inward along the tunnel entrance. Moreover, the first construction passage (6), second construction passage (7), and third construction passage (8) are all within the overlapping section of the fourth tunnel (4) and the second tunnel (2). Among them, the first construction passage (6), second construction passage (7), and third construction passage (8) are all synchronously connected to the second tunnel (2), third tunnel (3), fourth tunnel (4), and fifth tunnel (5). The fourth construction passage (9) is connected to the second tunnel (2) and the fourth tunnel (4). At the third tunnel (3), a fifth working face, a first working face, a second working face, and a third working face are successively arranged inward from the tunnel entrance. At the fourth tunnel (4), a seventh working face and a fourth working face are successively arranged inward from the tunnel entrance. At the fifth tunnel (5), a sixth working face is arranged inward 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. The fourth working face is connected to the fourth construction passage. The ventilation layout structure includes a number of forced draft fans, a number of jet fans, and a number of air separation curtains. The forced draft fans achieve ventilation for the corresponding working faces through the corresponding air channels. The jet fans are arranged at the intersections or turning parts between the tunnels. The air separation curtains are arranged at the intersection positions between the second tunnel and the other tunnels.

2. The ventilation layout structure of the small clear distance tunnel constructed adjacent to the existing tunnel group according to claim 1, characterized in that: The air duct includes an air duct in four stages. The air duct in the first stage 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 passage is completed. It includes a first air duct (12), a second air duct (13), and a third air duct (14) respectively connected to the forced draft fan. The first air duct (12) is set as an air duct extending along the fifth tunnel (5) to the sixth working face. At the same time, the first air duct (12) is paralleled with an air duct that extends to the first working face after passing through the first construction passage (6) at the first construction passage (6). The second air duct (13) is set as an air duct that passes through the fourth construction passage (4) from the tunnel entrance of the second tunnel (2) and then extends to the fourth working face. At the same time, the second air duct (13) is paralleled with an air duct that extends to the third working face after passing through the third construction passage (8) at the third construction passage (8). The third air duct (14) is set as an air duct that extends from the tunnel entrance of the second tunnel (2) to the second working face; The air duct in the second stage is used for ventilation during the construction of the third tunnel (3), the fourth tunnel (4), and the fifth tunnel (5) after the backfilling on the side of the second tunnel (2) near the tunnel entrance is completed. It includes a fourth air duct (15), a fifth air duct (16), a sixth air duct (17), a seventh air duct (18), and an eighth air duct (19) respectively connected to the forced draft fan. The fourth air duct (15) is an air duct extending along the fifth tunnel (5) to the sixth working face. At the same time, the fourth air duct (15) is paralleled with an air duct that extends to the first working face after passing through the first construction passage (6) at the first construction passage (6). The fifth air duct (16) is an air duct that passes through the first construction passage (6) and the fourth construction passage (9) from the tunnel entrance of the fifth tunnel (5) and then extends to the fourth working face. At the same time, the fifth air duct (16) is paralleled with an air duct that extends to the third working face after passing through the third construction passage (8) at the third construction passage (8). The sixth air duct (17) is an air duct that passes through the first construction passage (6) from the tunnel entrance of the fifth tunnel and extends to the second working face. The seventh air duct (18) is an air duct that extends from the tunnel entrance of the fourth tunnel (4) to the seventh working face, and the eighth air duct (19) is an air duct that extends from the tunnel entrance of the third tunnel (3) to the fifth working face; The air duct in the third stage is used for ventilation during the construction of the fourth tunnel (4) and the fifth tunnel (5) after multiple working faces on the third tunnel (3) are connected and the sixth working face is located on the side of the second cross passage away from the tunnel entrance. It includes a ninth air duct (20), a tenth air duct (21), and an eleventh air duct (22) respectively connected to the forced draft fan. The ninth air duct (20) is an air duct extending along the fifth tunnel (5) to the sixth working face. The tenth air duct (21) is an air duct that passes through the second construction passage (7) and the fourth construction passage (9) from the tunnel entrance of the fifth tunnel (5) and then extends to the fourth working face. The eleventh air duct (22) is an air duct extending 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 penetrated, and includes a twelfth air duct (23) and a thirteenth air duct (24) respectively connected to the pressure-in fan. The pressure-in fan of the twelfth air duct (23) is arranged at the span position of the fifth tunnel. The twelfth air duct (23) is an air duct connected to the corresponding pressure-in fan and extends to the fourth working surface after passing through the third construction channel (8) and the fourth construction channel (9). The thirteenth air duct (24) is an air duct extending along the fourth tunnel (4) to the seventh working surface.

3. The ventilation layout structure of the small clear distance tunnel constructed adjacent to the existing tunnel group according to claim 2, characterized in that: The pressure-in fans in different stages can be reused, and the pressure-in fans located outside the tunnel are arranged near the fifth tunnel (5).

4. The ventilation layout structure of the small clear distance tunnel constructed adjacent to the existing tunnel group according to claim 2, characterized in that: In the first stage, the third air duct (14) is connected in parallel with the second construction channel (7) to a wind duct that passes through the second construction channel (7) and extends to the side of the sixth working surface; in the second stage, the sixth air duct (17) is connected in parallel with the second construction channel (7) to a wind duct that passes through the second construction channel (7) and extends to the side of the sixth working surface. In the third stage, an eighth working surface connected to the third construction channel is provided in the fifth tunnel, and also includes a fourteenth air duct (25), which is an air duct that passes through the second construction channel (7) and the third construction channel (8) from the tunnel opening of the fifth tunnel (5) to the eighth working surface.

5. The ventilation layout structure of the small clear distance tunnel constructed adjacent to the existing tunnel group according to claim 1, characterized in that: A fifth construction passage (10) connected to a fourth tunnel (4) is arranged at one end of the second tunnel (2) away from the tunnel entrance, the fourth tunnel (4) having a ninth working surface constructed through the fifth construction passage (10), and a tenth working surface constructed toward a third tunnel (3) is arranged at one end of the second tunnel (2) away from the tunnel entrance, the ventilation of the ninth working surface and the tenth working surface being achieved by a ventilation assembly arranged in the second tunnel (2).

6. The ventilation layout structure of the small clear distance tunnel constructed adjacent to the existing tunnel group according to claim 5, characterized in that: The ventilation assembly comprises a fan frame, a damper and a wind screen arranged in the second tunnel (2); a pressure-in fan is arranged outside the damper; the other end of the pressure-in fan is connected to the outside through a sixth construction channel (11) and a construction inclined shaft on the side of the fourth tunnel closest to the tunnel entrance; the sixth construction channel (11) is used to connect the construction inclined shaft with an end of the second tunnel (2) farthest from the tunnel entrance.

7. The ventilation layout structure of the small clear distance tunnel constructed adjacent to the existing tunnel group according to claim 1, characterized in that: The intervals between the first construction channel (6), the second construction channel (7) and the third construction channel (8) are between 200-300 m.

8. The ventilation layout structure of the small clear distance tunnel constructed adjacent to the existing tunnel group according to claim 1, characterized in that: The distance between adjacent jet fans is between 400-500m.

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