A multifunctional tunnel construction auxiliary facility and its design method

Abstract

This invention discloses a multifunctional tunnel construction auxiliary facility and its design method, relating to the field of tunnel and underground engineering construction technology. The multifunctional tunnel construction auxiliary facility is a sunken space installed on the inverted concrete of the tunnel. The sunken space extends from near the tunnel face to the outside of the tunnel, and its top is sealed by a precast cover plate. An escape pipe is provided at the end of the sunken space near the tunnel face. This auxiliary facility integrates multiple functions such as assisting personnel escape, assisting construction ventilation, and assisting construction backslope drainage, achieving multiple functions in one facility. This greatly reduces the impact of traditional pipelines on construction, reduces the demand for tunnel construction space, and optimizes ventilation ducts and backslope drainage collection wells that are constrained by the construction environment. While ensuring construction safety, it achieves the goals of accelerating construction progress, improving ventilation efficiency, and reducing energy consumption, while also realizing a combination of permanent and temporary facilities, reducing project investment.

Description

Technical Field

[0001] This invention relates to the field of tunnel and underground engineering construction technology, and in particular to a multifunctional tunnel construction auxiliary facility and its design method. Background Technology

[0002] Tunnel construction is characterized by limited working space, harsh working environment, and significant geological influences, often presenting numerous uncertainties that impact construction safety. In addition to taking preventative measures before construction begins, sufficient safety protocols should be in place to support escape and rescue efforts in the event of an emergency.

[0003] From a structural safety perspective, collapses are a relatively common safety accident in tunnel construction, with "closing-door" collapses being particularly typical. Currently, the industry mainly addresses collapses and other emergencies by installing circular escape tunnels made of steel or other composite materials near the tunnel face to withstand rockfall impacts. Many studies have also proposed setting up emergency refuge chambers near the tunnel face, connected to these escape tunnels for personnel escape and rescue after an accident. The escape tunnels need to extend from near the tunnel face to the section where the secondary lining structure is completed. Considering the spacing requirements between different construction processes, these tunnels often need to be over 100 meters, sometimes even reaching 150 meters. As the tunnel face continues to advance, the escape tunnels need to be disassembled, moved forward, and reinstalled.

[0004] From the perspective of the breathing needs of construction workers, the tunnel needs to ensure a supply of 3m³ of fresh air per person per minute when workers are working. 3 Currently, most existing construction ventilation systems use a forced-in method, employing flexible ducts that hang on the tunnel sidewalls. These ducts are often bent at intersections with various work platforms within the tunnel, and sharp objects such as reinforcing bars and machinery inevitably cause damage. Bending increases local resistance to airflow, resulting in power loss; while damage (such as tears or holes) increases air leakage, leading to insufficient actual air supply at the tunnel face.

[0005] For tunnels excavated downhill, groundwater accumulates near the tunnel face due to the tunnel's longitudinal slope. If not drained promptly, this groundwater will soak the surrounding rock for an extended period, worsening the construction environment and reducing the bearing capacity of the surrounding rock. Therefore, reverse slope drainage is crucial during construction. Currently, reverse slope drainage on-site often involves excavating sump pits or placing collection tanks on the tunnel sidewalls, using pumps in stages to pump out the groundwater. Excavating sump pits encroaches on the construction space of the lining structure, causing unreasonable local stress on the structure and even affecting its safety. Placing collection tanks on the tunnel sidewalls encroaches on the construction space within the tunnel, and these tanks are often significantly higher than the tunnel surface, requiring higher pump head. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a multifunctional tunnel construction auxiliary facility and its design method. Based on its unique location, material properties, and structural form, it can assist personnel in escaping during tunnel construction emergencies, serve as a ventilation or exhaust duct for tunnel construction, and provide space for drainage on the reverse slope of tunnel construction. This multifunctional tunnel construction auxiliary facility integrates these three functions into the invert arch filling layer, reducing the need for construction space, minimizing interference with construction, thereby improving construction efficiency and saving on project investment.

[0007] The technical solution adopted in this invention is as follows:

[0008] A multifunctional tunnel construction auxiliary facility is a sinking space installed on the inverted concrete of a tunnel. The sinking space is located on one side of the tunnel cross-section centerline, extending from near the tunnel face to the outside of the tunnel. The top of the sinking space is closed by a precast cover plate, the top surface of which is flush with the top surface of the inverted concrete. An escape pipe is installed at the end of the sinking space near the tunnel face via an escape pipe foundation. One end of the escape pipe extends into the sinking space, and the other end extends to the tunnel face.

[0009] Furthermore, the sunken space has a rectangular cross-section, and the escape pipe has a circular cross-section.

[0010] Furthermore, a fan is installed at one end of the sunken space extending to the outside of the tunnel, and the fan is located at the tunnel entrance; when the fan blows air in the forward direction, fresh air from outside the tunnel is pressurized by the fan and sent to the vicinity of the working face along the sunken space and escape pipe; when the fan provides the power for reverse exhaust, the polluted gas inside the tunnel is discharged outside the tunnel along the escape pipe and sunken space.

[0011] Furthermore, the end of the sunken space is provided with an end seal for sealing the outer edge of the escape pipe.

[0012] When the tunnel excavation direction is downhill, the longitudinal slope of the sinking space is consistent with the longitudinal slope of the tunnel; several water collection wells are set at certain intervals at the bottom of the sinking space, and each water collection well is equipped with a water pump. The water pump is connected to a drainage pipe, which extends to the next water collection well.

[0013] A design method for a multifunctional tunnel construction auxiliary facility, specifically for an escape tunnel construction auxiliary facility; the cross-section of the sunken space is larger than the cross-section of the escape pipe; the height and width of the sunken space cross-section are expressed by the following formula:

[0014]

[0015] In the formula, b is the cross-sectional clear width of the sunken space, in meters; h is the cross-sectional clear height of the sunken space, in meters; d is the inner diameter of the circular escape pipe, in meters; and t is the wall thickness of the circular escape pipe, in meters.

[0016] If the escape tunnel uses a metal circular tube with an inner diameter of 0.95m and a wall thickness of 0.01m, the height and width of the sunken space section must both be greater than 0.97m.

[0017] A design method for a multifunctional tunnel construction auxiliary facility, which is designed for a tunnel construction auxiliary facility with ventilation function; construction ventilation needs to provide sufficient fresh air for workers at the tunnel face to breathe, while also removing carbon dioxide generated by breathing and dust generated during construction.

[0018] When constructing ventilation systems for sunken spaces and escape tunnels, the cross-sectional dimensions of the sunken space must meet the following formula:

[0019]

[0020] In the formula, Q represents the required air volume for tunnel construction ventilation, in meters (m³). 3 / s; v is the air velocity of the ventilation duct, in m / s; b is the cross-sectional clear width of the sunken space, in m; h is the cross-sectional clear height of the sunken space, in m.

[0021] A design method for a multifunctional tunnel construction auxiliary facility, which includes a drainage function for the tunnel construction auxiliary facility; during construction, reverse slope drainage requires that the water inflow near the tunnel face be pumped out to the outside of the tunnel through a relay formula using a water collection well, a water pump and a drainage pipe; the volume of each water collection well needs to be greater than the water inflow of the tunnel within the distance between the current water collection well and the previous water collection well;

[0022] The dimensions of a water collection well are expressed by the following formula:

[0023]

[0024] In the formula, V j b is the volume of the water collection well, in m3; h is the net cross-sectional width of the sunken space, in m; j The depth of the water collection well, in meters (m); l j The longitudinal length of the water collection well is in meters; i is the longitudinal slope of the tunnel; Q w The predicted water inflow is given by L1, which is the distance between the collection wells, in meters; L is the total length of the tunnel, in meters; and k is the surplus coefficient, which is generally greater than 1.

[0025] A design method for a multifunctional tunnel construction auxiliary facility is provided. This method addresses the need for the multifunctional tunnel construction auxiliary facility to serve multiple purposes, including escape, ventilation, and drainage. The cross-sectional dimensions of the sunken space should satisfy the following formula:

[0026]

[0027] In the formula, Q represents the required air volume for tunnel construction ventilation, in meters (m³). 3 / s; v is the wind speed of the ventilation duct, in m / s; d is the inner diameter of the circular escape duct, in m; t is the wall thickness of the circular escape duct, in m; b is the cross-sectional clear width of the sunken space, in m; h is the cross-sectional clear height of the sunken space, in m.

[0028] The beneficial effects of this invention are:

[0029] (1) The multi-functional tunnel construction auxiliary facility is simple in design and convenient to construct. It integrates multiple functions and can simultaneously achieve the functions of assisting personnel escape, assisting construction ventilation, and assisting construction reverse slope drainage.

[0030] (2) The multi-functional tunnel construction auxiliary facility can be used in conjunction with the escape pipeline to greatly reduce the length of the escape pipeline, shorten the time for dismantling and reassembling the escape pipeline, and accelerate the construction progress while ensuring safety.

[0031] (3) The auxiliary facility is used to replace the traditional ventilation pipe. The facility is located in the invert arch filling layer, which reduces the demand on the tunnel construction section. The facility is laid out in a fixed position along the longitudinal direction of the tunnel, with a smooth transition, avoiding problems such as pipe bending caused by avoiding the construction trolley. The facility is relatively enclosed, which reduces the air leakage rate of the ventilation pipe and improves the construction ventilation efficiency.

[0032] (4) This facility can be used for reverse slope drainage during construction. The water collection well does not occupy construction space and can also be used as a temporary water storage pool for tunnel water inflow. After operation, the facility can be used for drainage. At the same time, the water collection well can be used as a sedimentation tank and maintenance well for the water ditch. It takes into account both the construction period and the operation period, and greatly saves project investment. Attached Figure Description

[0033] Figure 1 This is a schematic diagram showing the layout of the multifunctional tunnel construction auxiliary facilities of the present invention inside the tunnel;

[0034] Figure 2 Longitudinal cross-section of the construction auxiliary facility of this invention for emergency escape of construction personnel going up the steps;

[0035] Figure 3Longitudinal cross-section of the emergency escape route for construction workers descending the steps, as shown in this invention's construction auxiliary facilities;

[0036] Figure 4 This is a cross-sectional layout diagram of the multifunctional construction auxiliary facilities of the present invention;

[0037] Figure 5 This is a cross-sectional layout diagram of the construction auxiliary facilities for the present invention during reverse slope drainage construction.

[0038] Figure 1 —5, 1—sunken space, 2—tunnel invert arch filling concrete, 3—precast cover plate, 4—end seal, 5—escape pipe, 6—cover plate, 7—water pump, 8—drainage pipe, 9—escape pipe foundation, 10—upper bench face, 11—lower bench face, 12—water collection well. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] For ease of explanation, spatial relative terms such as “above,” “below,” “left,” and “right” may be used herein to describe the relationship of one element or feature shown in the figure relative to another element or feature. It should be understood that, in addition to dealing with the orientation shown in the figure, spatial terms are intended to include different orientations of the device in use or operation. For example, if the device in the figure is inverted, an element described as being “below” other elements or features would be defined as being “above” other elements or features. Therefore, the exemplary term “below” can encompass both above and below. The device may be positioned in other ways, and the spatial relative descriptions used herein can be interpreted accordingly.

[0041] Example 1

[0042] To address the escape problem during tunnel construction, this embodiment proposes a multifunctional tunnel construction auxiliary facility. For example... Figure 1 As shown, this multi-functional tunnel construction auxiliary facility is a sinking space 1 installed on the inverted concrete 2 of the tunnel, and the sinking space 1 is located on one side of the tunnel cross-section centerline; as Figure 2 and Figure 3As shown, the sunken space 1 extends from near the upper bench face 10 or the lower bench face 11 to the outside of the tunnel. The top of the sunken space 1 is sealed by a precast cover plate 3, the top surface of which is flush with the top surface of the tunnel invert filling concrete 2. An escape pipe 5 is installed at the end of the sunken space 1 near the face via an escape pipe foundation 9. One end of the escape pipe 5 extends into the sunken space 1, and the other end extends to the upper bench face 10 or the lower bench face 11. The tunnel excavation direction is shown by the arrow in the figure.

[0043] like Figure 2 and Figure 3 As shown, the sunken space 1 is flush with the end of the tunnel invert arch filling concrete 2 near the tunnel face, while the other end leads to the outside of the tunnel. The end of the escape pipe 5 near the tunnel face overlaps with the sunken space 1. In the event of a sudden accident such as a collapse near the tunnel face, as shown by the arrow in the figure, construction workers can escape into the sunken space 1 through the escape pipe 5 and open the precast cover 3 at a safe location to escape. Using this multi-functional tunnel construction auxiliary facility to assist in escape can reduce the size of the escape pipe 5, make the installation of the escape pipe 5 more convenient during construction, and facilitate the movement of the escape pipe 5 forward as the tunnel face is excavated.

[0044] Furthermore, as a preferred technical solution in this embodiment, such as Figure 4 As shown, in this embodiment, the sunken space 1 has a rectangular cross-section, and the escape pipe 5 has a circular cross-section. The combined use of the sunken space 1 and the escape pipe 5 can significantly reduce the length of the escape pipe 5, shorten the time required for dismantling and reassembling it, and accelerate the construction progress while ensuring safety.

[0045] Example 2

[0046] Based on the multifunctional tunnel construction auxiliary facilities provided in Embodiment 1, in this embodiment, a fan is provided at one end of the sunken space 1 extending to the outside of the tunnel. The fan is located at the tunnel entrance, and the auxiliary construction ventilation function is achieved by the fan in conjunction with the sunken space 1 and the escape pipe 5.

[0047] Specifically, such as Figure 2 and Figure 3As shown, this multi-functional construction auxiliary facility starts at the tunnel entrance, with a fan installed at one end of the sunken space 1 extending outside the tunnel, and ends at the tunnel invert end. When used as a construction ventilation supply duct, fresh air from outside the tunnel is pressurized by the fan and then transported along the sunken space 1 and escape pipe 5 to the vicinity of the tunnel face. When used as a construction ventilation exhaust duct, the fan provides the power for reverse exhaust, and polluted gas inside the tunnel is discharged outside the tunnel along the escape pipe 5 and sunken space 1. Compared with traditional separately installed supply and exhaust ducts, this multi-functional construction auxiliary facility avoids bends and damage, preventing increased local ventilation resistance due to bends and cross-sectional changes, and also solves the problem of increased air leakage due to damage to flexible ducts.

[0048] It should be noted that when this multi-functional construction auxiliary facility also serves as a construction escape pipeline 5 and a ventilation pipeline, such as Figure 2 and Figure 3 As shown, an end seal 4 is required at the end of the sunken space 1 to seal the outer edge of the escape pipe 5. The end seal 4 is sealed with an airtight soft material, such as foam board, to avoid air loss. In addition, it is necessary to ensure that sealing measures are used to seal the space between the prefabricated cover plates 3 and between the prefabricated cover plates 3 and the top of the sunken space 1 to avoid air loss.

[0049] Example 3

[0050] Based on the multifunctional tunnel construction auxiliary facilities provided in Example 1, such as Figure 4 and Figure 5 As shown, in this embodiment, the longitudinal slope of the multi-functional construction auxiliary facility is consistent with the longitudinal slope of the tunnel. When the tunnel excavation direction is downhill, water collection wells 12 are set at certain intervals at the bottom of the sinking space 1. Groundwater near the tunnel face is pumped to the water collection wells 12 by water pump 7. Then, the water in the first water collection well 12 is pumped to the next water collection well 12 by water pump 7, and so on, until the groundwater is discharged outside the tunnel. The difference from conventional practices is that this multi-functional construction auxiliary facility is suitable for reverse slope drainage, does not affect the tunnel construction space, and does not affect the main structure of the tunnel. At the same time, the water collection wells 12 can also serve as sedimentation tanks for the drainage ditch during tunnel operation, facilitating the maintenance of the drainage ditch.

[0051] It should be noted that, to avoid localized resistance caused by sudden expansion and contraction during ventilation at the location of the water collection well 12, a cover plate 6 needs to be installed above the water collection well 12 to ensure cross-sectional consistency. The cover plate 6 can be made of materials with high rigidity and strength, such as steel or wood, to minimize its thickness. After the tunnel construction is completed and the tunnel enters the operational phase, the cover plate 6 of the water collection well 12 will be removed, and the water collection well 12 will be used as a sedimentation tank for the drainage ditch.

[0052] Example 4

[0053] Based on the multifunctional tunnel construction auxiliary facilities provided in Embodiments 1, 2, and 3, this embodiment provides a design method for multifunctional tunnel construction auxiliary facilities.

[0054] Specifically, when this multi-functional tunnel construction auxiliary facility is used only to assist in construction escape:

[0055] like Figure 1 and Figure 4 As shown, to achieve the connection between the escape pipe 5 and the sunken space 1, the cross-section of the sunken space 1 needs to be larger than the cross-section of the escape pipe 5 to allow personnel to pass through in an emergency. The height and width of the cross-section of the sunken space 1 can be expressed by the following formula:

[0056]

[0057] In the formula, b is the cross-sectional clear width of the sunken space, in meters; h is the cross-sectional clear height of the sunken space, in meters; d is the inner diameter of the circular escape pipe 5, in meters; and t is the wall thickness of the circular escape pipe 5, in meters.

[0058] Escape pipes in tunnel construction often use metal round pipes with an inner diameter of 0.95m and a wall thickness of 0.01m. Therefore, when this facility assists personnel in escaping, its cross-section height and width must both be greater than 0.97m.

[0059] When this multi-functional tunnel construction auxiliary facility is used to assist with construction ventilation:

[0060] Construction ventilation needs to provide workers at the working face with sufficient fresh air for breathing, while also removing carbon dioxide produced by breathing and dust generated during construction.

[0061] When constructing auxiliary ventilation for sunken space 1 and escape pipe 5, the cross-sectional dimensions of sunken space 1 must meet the following formula:

[0062]

[0063] In the formula, Q represents the required air volume for tunnel construction ventilation, in meters (m³). 3 / s; v is the air velocity of the ventilation duct, in m / s; b is the cross-sectional clear width of the sunken space, in m; h is the cross-sectional clear height of the sunken space, in m.

[0064] When this multi-functional tunnel construction auxiliary facility is used to assist in reverse slope drainage during construction:

[0065] During construction, reverse slope drainage requires pumping the water inflow near the tunnel face out through a relay method using sump 12, pump 7, and drainage pipe 8. To meet the groundwater pumping needs, the volume of each sump 12 needs to be greater than the tunnel's water inflow within the distance between that sump 12 and the previous sump 12; to prevent water overflow from the sump 12, a certain margin should be considered.

[0066] like Figure 4 and Figure 5 As shown, the dimensions of the water collection well 12 can be expressed by the following formula:

[0067]

[0068] In the formula: V j 12 represents the volume of the water collection well, in m³; b represents the net cross-sectional width of the sunken space, in meters; h represents the volume of the water collection well, in m. j The depth of well 12 is in meters (m); j The longitudinal length of the water collection well is 12, in meters; i is the longitudinal slope of the tunnel; Q w The predicted water inflow is given for the entire tunnel length, in m³ / s; L1 is the spacing between the 12 collection wells, in meters; L is the total length of the tunnel, in meters; k is the surplus coefficient, which is generally greater than 1.

[0069] When the multi-functional tunnel construction auxiliary facility simultaneously serves three functions: assisting in construction escape, assisting in construction ventilation, and assisting in construction reverse slope drainage, its cross-sectional dimensions should simultaneously meet the requirements of the relevant regulations.

[0070] Equation 1 and Equation 2, i.e., the following formulas:

[0071]

[0072] In the formula, Q represents the required air volume for tunnel construction ventilation, in meters (m³). 3 / s; v is the wind speed of the ventilation duct, in m / s; d is the inner diameter of the circular escape duct 5, in m; t is the wall thickness of the circular escape duct 5, in m; b is the cross-sectional clear width of the sunken space, in m; h is the cross-sectional clear height of the sunken space, in m.

[0073] In summary, this multi-functional tunnel construction auxiliary facility features a simple design, convenient construction, and multiple functions, simultaneously assisting in personnel escape, construction ventilation, and drainage on the reverse slope. When used in conjunction with the escape pipe 5, this facility significantly reduces the length of the escape pipe 5, shortens the time required for its dismantling and reassembly, and ensures safety while accelerating construction progress. Replacing traditional ventilation ducts with this auxiliary facility, located within the invert arch filling layer, reduces the need for tunnel construction cross-sections. Its fixed location along the tunnel's longitudinal direction ensures a smooth transition, avoiding problems such as duct bending caused by avoiding construction trolleys. The relatively enclosed space reduces duct leakage and improves construction ventilation efficiency. For reverse slope drainage, the collection well 12 does not occupy construction space and can serve as a temporary reservoir for tunnel water inflow. After operation, it can be used for drainage. Simultaneously, the collection well 12 can function as a sedimentation tank and maintenance well for the drainage ditch, comprehensively considering both construction and operation periods and significantly saving on project investment.

[0074] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A design method for a multifunctional tunnel construction auxiliary facility, characterized in that: The multifunctional tunnel construction auxiliary facility is a sinking space installed on the inverted concrete of the tunnel. The sinking space is located on one side of the centerline of the tunnel section, extending from near the tunnel face to the outside of the tunnel. The top of the sinking space is closed by a precast cover plate, and the top surface of the precast cover plate is flush with the top surface of the inverted concrete. An escape pipe is installed at the end of the sinking space near the tunnel face through an escape pipe foundation. One end of the escape pipe extends into the sinking space, and the other end extends to the tunnel face. The sunken space has a rectangular cross-section, and the escape pipe has a circular cross-section. A fan is installed at one end of the sunken space extending outside the tunnel, located at the tunnel entrance. When the fan blows air in the forward direction, fresh air from outside the tunnel is pressurized by the fan and sent to the vicinity of the tunnel face along the sunken space and escape pipes. When the fan provides reverse exhaust power, polluted gas inside the tunnel is discharged outside the tunnel along the escape pipes and the sunken space. An end seal is provided at the end of the sunken space to seal the outer edge of the escape pipes. When the tunnel excavation direction is downhill, the longitudinal slope of the sunken space is consistent with the longitudinal slope of the tunnel. Several water collection wells are set at certain intervals at the bottom of the sunken space. Each water collection well is equipped with a water pump, and the water pump is connected to a drainage pipe that extends to the next water collection well. In this design method, the cross-section of the sunken space is larger than that of the escape tunnel; the height and width of the sunken space cross-section are expressed by the following formula: Formula 1: In the formula, b is the cross-sectional clear width of the sunken space, in meters; h is the cross-sectional clear height of the sunken space, in meters; d is the inner diameter of the circular escape pipe, in meters; and t is the wall thickness of the circular escape pipe, in meters. If the escape tunnel uses a metal circular tube with an inner diameter of 0.95m and a wall thickness of 0.01m, the height and width of the sunken space section must both be greater than 0.97m.

2. The design method for the multifunctional tunnel construction auxiliary facility according to claim 1, characterized in that: Construction ventilation needs to provide workers at the working face with sufficient fresh air for breathing, while also removing carbon dioxide produced by breathing and dust generated during construction. When constructing ventilation systems for sunken spaces and escape tunnels, the cross-sectional dimensions of the sunken space must meet the following formula: Formula 2: In the formula, Q is the required air volume for tunnel construction ventilation, in m³ / s; v is the air velocity of the ventilation duct, in m / s; b is the cross-sectional net width of the sunken space, in m; and h is the cross-sectional net height of the sunken space, in m.

3. The design method for the multifunctional tunnel construction auxiliary facility according to claim 1, characterized in that: During construction, reverse slope drainage requires pumping the water inflow near the tunnel face out of the tunnel through a relay method using sump wells, pumps, and drainage pipes; the volume of each sump well must be greater than the water inflow in the tunnel within the distance between the sump well and the previous sump well. The dimensions of a water collection well are expressed by the following formula: Formula 3: In the formula, denoted as , where is the volume of the water collection well, in m³; b is the net cross-sectional width of the sunken space, in m. The depth of the water collection well, in meters (m). This refers to the longitudinal length of the water collection well, in meters (m). i represents the longitudinal slope of the tunnel; Predicted water inflow for the entire tunnel length, in m³ / s; The distance between water collection wells, in meters; L is the total length of the tunnel, in meters (m). k is the abundance coefficient, which is generally greater than 1.

4. The design method for multifunctional tunnel construction auxiliary facilities according to claim 1, characterized in that: If the multi-functional tunnel construction auxiliary facility is required to serve three purposes—escape, ventilation, and drainage—the cross-sectional dimensions of the sunken space should meet the following formula: Formula 4: In the formula, Q is the required air volume for tunnel construction ventilation, in m³ / s; v is the wind speed of the ventilation duct, in m / s; d is the inner diameter of the circular escape duct, in m; t is the wall thickness of the circular escape duct, in m; b is the cross-sectional clear width of the sunken space, in m; and h is the cross-sectional clear height of the sunken space, in m.

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