Relay type underground excavation shed tunnel structure system and construction method

Abstract

The invention discloses a relay type underground excavation shed tunnel structure system and a construction method, and relates to the technical field of highway engineering. The relay type underground excavation shed tunnel structure system comprises a main tunnel structure, and the main tunnel structure adopts the following structures at an excavation section of a slope body: the main tunnel structure comprises a group of arc-shaped arch body structures, the group of arc-shaped arch body structures are arranged at intervals, the sides, close to the slope body, of the group of arc-shaped arch body structures are connected through a plurality of longitudinal pipes, and the other sides of the arc-shaped arch body structures are connected through a special-shaped beam body; a plurality of relay walls are arranged on the sides, close to the slope body, of the arc-shaped arch bodies at intervals, and the longitudinal pipe sheds penetrate through the relay walls; and a plurality of transverse steel pipe piles obliquely driven into the slope body are mounted at the top of the special-shaped beam body. According to the relay type underground excavation shed tunnel structure system, a stable upper-anchoring and lower-supporting bearing structure system is formed through the transverse steel pipe piles, the relay walls and the longitudinal pipe sheds, disturbance of shed tunnel underground excavation to a slope body is effectively isolated, it is ensured that a shed tunnel and a mountain body are stable in the tunnel construction process, and safe and rapid construction of shed tunnel underground excavation is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of highway engineering, and in particular to a relay-type dark-excavated shed tunnel structure system and a construction method. Background Art

[0002] As the expressway continues to extend to the western mountainous areas, the line will inevitably pass through river valleys, mountainsides and other biased areas. Shed tunnels have begun to emerge as an effective way to cross these areas. Traditional shed tunnels generally adopt open cut backfill, semi-arch cover excavation and other construction methods. There is a problem with the above construction methods: with the excavation of the shed tunnel, the disturbance to the slope body gradually increases, and it is easy to slip along the fracture surface during the excavation process, posing a major safety hazard. The main reason is that the disturbance of the slope body caused by the excavation of the shed tunnel is not properly controlled. In view of the above situation, whether it is possible to study a shed tunnel structure and construction method that can effectively control the disturbance of the slope body during the dark excavation process, so that the shed tunnel can be quickly and safely excavated is a difficult problem that needs to be solved urgently. Summary of the invention

[0003] Based on the current problems, the present invention provides a relay-type dark-excavation shed tunnel structure system and construction method, which aims to form a stable "upper anchor and lower support" load-bearing structure system through transverse steel pipe piles, relay walls and longitudinal pipe sheds, effectively isolate the disturbance of the shed tunnel dark excavation on the slope, ensure the stability of the shed tunnel and the mountain during tunnel construction, and realize safe and rapid construction of the shed tunnel dark excavation.

[0004] The technical solution adopted by the present invention is:

[0005] A relay-type dark excavation shed tunnel structure system, the relay-type dark excavation shed tunnel structure system includes a main tunnel structure, and the main tunnel structure adopts the following structure in the slope excavation section:

[0006] The main tunnel structure includes a group of arc-shaped arch structures, which are arranged at intervals. A group of arc-shaped arches are connected by a number of longitudinal pipes on one side close to the slope body and connected by a special-shaped beam on the other side. A group of arc-shaped arches are arranged with a number of relay walls at intervals on one side close to the slope body, and the longitudinal pipe shed runs through the relay wall. A number of transverse steel pipe piles driven obliquely into the slope body are installed above the top of the special-shaped beam body.

[0007] The transverse steel pipe piles are driven into the slope body and connected with the top of the special-shaped beam body to form an anchoring unit, through which the transverse upper side anchor of the main tunnel structure is realized; a plurality of longitudinal pipes form a longitudinal pipe rack, and the longitudinal pipe rack cooperates with the relay wall structure to form a longitudinal bearing unit, through which the lower side support of the main tunnel structure is realized when the excavation constraint of the rock and soil body is lost.

[0008] Furthermore, the arc-shaped arch structure includes a sleeve arch located at the outer circle of the arc-shaped arch structure, and a lining layer structure located at the inner circle and bottom of the arc-shaped arch structure.

[0009] Furthermore, the cross-section of the relay wall is a right-angled trapezoidal wall structure, one side of which extends into the main hole structure, and the other side is embedded in the slope body.

[0010] Furthermore, the special-shaped beam body includes a plurality of inclined columns arranged at intervals along the excavation direction of the shed tunnel. If a special-shaped supporting beam is installed on the top of the inclined column, a cap beam is installed on the bottom; the special-shaped supporting beam is connected to a group of circular arc arch structures and one side of the lining layer structure; the special-shaped beam body also includes a plurality of transverse connecting beams arranged at intervals along the excavation direction of the shed tunnel, and the cap beam is connected to the lining layer structure in the main tunnel structure through a plurality of transverse connecting beams.

[0011] Furthermore, the special-shaped support beam is installed with a cap beam obliquely above the main tunnel structure. The cap beam is located on the mountain side of the center line of the cross-section of the main tunnel structure, and the cap beam is connected to one end of the transverse steel pipe pile.

[0012] A construction method of a relay-type dark excavation shed tunnel structure system, based on the above-mentioned shallow buried biased relay-type dark excavation shed tunnel structure, comprises the following steps:

[0013] Step 1: excavate the mountain in a small area, clear out the working platform, and drive transverse steel pipe piles into the mountain of the slope. The ends of the transverse steel pipe piles are cast together with the cap beam;

[0014] Step 2, further excavate the mountain in a small area downwards, and construct the cap beam, inclined columns and special-shaped supporting beams;

[0015] Step 3, calculate and determine the spacing and number of relay walls based on geological conditions and the length of the shed hole;

[0016] Step 4: Determine the location of the relay wall based on the spacing and number of the relay walls, cast the relay wall after milling, reserve a guide pipe at a suitable position of the relay wall during the casting process, and ensure that the top of the relay wall has the same slope as the mountain surface;

[0017] Step 5, construct a longitudinal pipe shed from the sleeve arch position to the relay wall, and the pipe shed passes through the relay wall;

[0018] Step 6, excavating the main hole under the pipe shed and constructing the lining structure;

[0019] Step 7: When the main tunnel structure is excavated to the relay wall, the part of the relay wall in the main tunnel is removed by milling and excavation according to the tunnel contour, and the longitudinal pipe shed is continued to be built from the reserved guide sleeve of the relay wall to the next relay wall;

[0020] Step 8, continue to excavate the main hole under the pipe shed; repeat the above steps until the main hole is connected; when setting up the longitudinal pipe shed, its upper elevation angle is 1 to 3 degrees, so that the longitudinal pipes form an arch as a whole.

[0021] Furthermore, in step 3, the process of determining the spacing of the relay walls is as follows:

[0022] Step 3.1, calculate the remaining sliding force of the slope:

[0023]

[0024] In the formula, F 1 、F 2 、F 3 is the residual sliding force of each part of the slope, where F 1 Represents the first slope section, F 2 represents the middle slope body, F 3 Represents the tail slope body close to the main tunnel structure; γ t is the safety factor; G 1 , G 2 , G 3 is the weight of the potential sliding soil in each part of the slope; θ 1 ,θ 2 ,θ 3 It is the angle between the potential sliding soil of each part of the slope and the horizontal plane; is the internal friction angle of each part of the slope; c 1 、c 2 、c 3 is the cohesion of the rock and soil in each part of the slope; l 1 , l 2 , l 3 is the potential sliding length of soil at each part of the slope; ψ 2 , 3 is the load transfer coefficient between slopes,

[0025] Step 3.2, calculate the remaining sliding force that the bearing unit formed by the relay wall and the longitudinal pipe roof needs to bear:

[0026] P=ξF 3

[0027] Where P is the residual sliding force that the load-bearing unit needs to bear; ξ is the distribution coefficient;

[0028] The load-bearing unit formed by the relay wall and the longitudinal pipe shed is simplified into a single-span statically indeterminate beam with fixed connections at both ends. The limit disturbance of a single longitudinal pipe under the action of the residual sliding force is calculated as follows:

[0029]

[0030] Where q is the residual sliding force on a single longitudinal pipe; D is the longitudinal pipe layout spacing of the longitudinal pipe rack; C is the layout range of the longitudinal pipe rack; w maxis the mid-span deflection of the longitudinal pipe shed; L is the length of the longitudinal pipe between the relay walls; E is the elastic modulus of the longitudinal pipe shed; I is the section moment of inertia of the longitudinal pipe shed and the grouting body; d is the diameter of a single longitudinal pipe;

[0031] Step 3.3, calculate the maximum tensile stress of a single longitudinal tube under the residual sliding force:

[0032]

[0033] In the formula, σ max is the maximum tensile stress of a single longitudinal tube;

[0034] Step 3.4, based on the calculation of the ultimate disturbance of a single longitudinal pipe and the maximum tensile stress of a single longitudinal pipe, calculate the ultimate disturbance of a single longitudinal pipe and the pipe shelf length L under the allowable stress condition respectively. 1 , L 2 ;

[0035]

[0036] Step 3.5, the length L of a single longitudinal tube should be L 1 , L 2 The smaller of the two; the length L of a single longitudinal tube is the spacing of the relay walls.

[0037] The beneficial effects of the present invention are:

[0038] 1. The relay-type dark-cut shed tunnel structure system cleverly connects the shed tunnel arch lining layer structure and the special-shaped beam body into a force-bearing whole that mainly transmits axial force, thereby improving the anti-eccentric compression bearing capacity of the main tunnel structure.

[0039] 2. The relay-type dark-cut shed tunnel structure system uses relay walls and longitudinal pipe sheds to form a load-bearing whole, effectively isolating the disturbance caused by the excavation of shallow-buried biased shed tunnels to the mountain, ensuring that the stability of the mountain is not affected during the construction of the main tunnel structure.

[0040] 3. The relay wall of the relay-type dark-excavated shed tunnel structure system is excavated by milling, and the longitudinal main tunnel structure is constructed by dark excavation, which greatly reduces the slope excavation area, saves land and protects the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the overall structure of the relay-type dark excavation shed tunnel structure system of the present invention;

[0042] Figure 2 It is a schematic diagram of the end structure of the relay-type dark excavation shed tunnel structure system of the present invention;

[0043] Figure 3 It is a structural schematic diagram of the relay wall, longitudinal pipe shed and main hole structure of the present invention;

[0044] Figure 4 It is a partial structural schematic diagram of the relay wall and the longitudinal pipe shed of the present invention;

[0045] Figure 5 It is a schematic diagram of mechanical analysis of the relay-type dark excavation shed tunnel structure system of the present invention;

[0046] Figure 6 is a cross-sectional view of the relay wall of the present invention;

[0047] In the figure, 1 is an arc-shaped arch structure, 2 is a slope, 3 is a longitudinal pipe, 4 is a special-shaped beam, 5 is a relay wall, 6 is a transverse steel pipe pile, 7 is a longitudinal pipe shed, 8 is an arch, 9 is a lining structure, 10 is an inclined column, 11 is a special-shaped supporting beam, 12 is a cap beam, 13 is a transverse connecting beam, 14 is a crown beam, and 15 is a guide sleeve. DETAILED DESCRIPTION

[0048] The following will be combined with the accompanying drawings of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In view of the problem that the disturbance control of the slope body caused by the current shed tunnel excavation process is not in place, this embodiment provides a relay-type dark excavation shed tunnel structure system, which includes a main tunnel structure. The main tunnel structure adopts the following structure in the slope body excavation section:

[0050] like Figure 1 and Figure 2 As shown, the main tunnel structure includes a group of arc-shaped arch structures 1, which are arranged at intervals. The arc-shaped arches are connected by a plurality of longitudinal tubes 3 on one side close to the slope body 2 and by a special-shaped beam body 4 on the other side. Figure 1 , Figure 2 and Figure 4 As shown, a group of arc-shaped arches are provided with a plurality of relay walls 5 at intervals near one side of the slope body 2 , and a longitudinal pipe rack 7 passes through the relay wall 5 .

[0051] Among them, Figure 1 As shown, the arc-shaped arch structure 1 includes a sleeve arch 8 located at the outer circle of the arc-shaped arch structure 1, and a lining layer structure 9 located at the inner circle and bottom of the arc-shaped arch structure 1. Figure 1 , Figure 2 and Figure 3As shown, the special-shaped beam body 4 includes a plurality of inclined columns 10 arranged at intervals along the excavation direction of the shed hole, and a special-shaped support beam 11 is installed on the top of the inclined column 10, and a cap beam 12 is installed on the bottom; the special-shaped support beam 11 is connected to a group of arc-shaped arch structures 1 and one side of the lining layer structure 9. Figure 1 As shown, the special-shaped beam body 4 also includes a plurality of transverse connecting beams 13 arranged at intervals along the excavation direction of the shed tunnel, and the cap beam 12 is connected to the lining layer structure 9 in the main tunnel structure through the plurality of transverse connecting beams 13.

[0052] In addition, a plurality of transverse steel pipe piles 6 are installed on the top of the special-shaped beam body 4 and are driven obliquely into the slope body 2. Specifically, Figure 2 As shown, the special-shaped support beam 11 is installed with a cap beam 14 obliquely above the main tunnel structure. The cap beam 14 is located on the mountain side of the center line of the main tunnel structure cross section. The cap beam 14 is connected to one end of the transverse steel pipe pile 6.

[0053] like Figure 2 As shown, the transverse steel pipe pile 6 is driven into the slope body 2, and the transverse steel pipe pile 6 is connected to the top of the special-shaped beam body 4 to form an anchoring unit, and the transverse upper side anchor of the main hole structure is realized through the anchoring unit. Figure 1 , Figure 3 and Figure 4 As shown, a plurality of longitudinal pipes 3 form a longitudinal pipe shed 7, and the longitudinal pipe shed 7 cooperates with the relay wall 5 to form a longitudinal bearing unit. When the excavation constraint of the rock and soil body is lost, the lower side support of the main tunnel structure is achieved through the longitudinal bearing unit.

[0054] Further, as a preferred technical solution of this embodiment, Figure 4 and Figure 6 As shown, in this embodiment, the cross-section of the relay wall 5 is a right-angled trapezoidal wall structure, one side of the relay wall 5 extends into the main hole structure, and the other side is embedded in the slope body 2.

[0055] The mechanical principle of the relay-type dark excavation shed tunnel structure system is as follows:

[0056] The transverse steel pipe pile 6 is driven into the slope body 2 before the main tunnel structure is constructed. The end of the transverse steel pipe pile 6 is connected to the crown beam 14 to form an anchoring unit to achieve the horizontal "upper anchor". In order to avoid the deformation of the longitudinal pipe shed 7 due to the loss of the end constraint of the longitudinal pipe shed 7 as the rock and soil body is excavated during the dark excavation of the main tunnel structure, a number of relay walls 5 are set up. The relay walls 5 cooperate with the longitudinal pipe shed 7 to form a stable longitudinal bearing unit to achieve "lower support".

[0057] After the main tunnel structure is excavated, the soil at the foot of the slope is removed. The upper soil tends to slide downward due to the loss of support constraints, thereby generating a sliding force. This sliding force deducts the friction force of the sliding surface to form a residual sliding force. The residual sliding force is first borne by the anchor unit, and the rest acts on the bearing unit. The mechanical principle is as follows: Figure 5 shown.

[0058] Because the load-bearing unit formed by the transverse steel pipe piles 6, the relay wall 5 and the longitudinal pipe shed 7 bears all the remaining sliding force, blocking the sliding trend and displacement of the slope soil, thereby effectively isolating and blocking the disturbance caused by the excavation of the shed tunnel, ensuring the safety and stability of the mountain and the shed tunnel.

[0059] Based on the above relay-type dark excavation shed tunnel structure system, this embodiment also provides a construction method of the relay-type dark excavation shed tunnel structure system, and the construction method includes the following steps:

[0060] Step 1, excavate the mountain in a small area, clear out the working platform, and drive transverse steel pipe piles 6 into the mountain of the slope body 2, and cast the ends of the transverse steel pipe piles 6 together with the cap beam 14;

[0061] Step 2, further excavating the mountain in a small area downward, constructing the cap beam 12, the inclined column 10 and the special-shaped support beam 11;

[0062] Step 3, calculating and determining the spacing and number of relay walls 5 according to geological conditions and the length of the shed hole;

[0063] Step 4, based on the spacing and number of relay walls 5, determine the position of relay wall 5, cast relay wall 5 after milling, reserve guide pipes at appropriate positions of relay wall 5 during casting, and make the top of relay wall 5 consistent with the slope of the mountain surface;

[0064] Step 5, a longitudinal pipe shed 7 is installed from the position of the sleeve arch 8 to the relay wall 5, and the pipe shed passes through the relay wall 5;

[0065] Step 6, excavating a main hole below the pipe shed and constructing a lining structure 9;

[0066] Step 7, when the main tunnel structure is excavated to the relay wall 5, the part of the relay wall 5 in the main tunnel is removed by milling and excavation according to the tunnel contour, and the longitudinal pipe shed 7 is continued to be installed from the reserved guide sleeve 15 of the relay wall 5 to the next relay wall 5;

[0067] Step 8, continue to excavate the main hole under the pipe shed; repeat the above steps until the main hole is connected; when the longitudinal pipe shed 7 is installed, its upper elevation angle is 1 to 3 degrees, so that the plurality of longitudinal pipes 3 form an arch as a whole.

[0068] Further, such as Figure 5 As shown, in step 3, the process of determining the spacing of the relay wall 5 is as follows:

[0069] Step 3.1, calculate the remaining sliding force of the slope:

[0070]

[0071] In the formula, F 1 、F 2 、F3 is the residual sliding force of each part of the slope, where F 1 Represents the first slope 2, F 2 Represents the middle slope body 2, F 3 Represents the tail slope body 2 close to the main tunnel structure; γ t is the safety factor, generally 1.3; G 1 , G 2 , G 3 is the weight of the potential sliding soil in each part of the slope; θ 1 ,θ 2 ,θ 3 It is the angle between the potential sliding soil of each part of the slope and the horizontal plane; is the internal friction angle of each part of the slope; c 1 、c 2 、c 3 is the cohesion of the rock and soil in each part of the slope; l 1 , l 2 , l 3 is the potential sliding length of soil at each part of the slope; ψ 2 for Figure 5 Medium G 1 The corresponding slope body and G 2 The load transfer coefficient between the corresponding slope bodies, ψ 3 G 2 The corresponding slope body and G 3 The load transfer coefficient between the slope bodies is calculated as follows:

[0072]

[0073] Step 3.2, calculate the remaining sliding force that the bearing unit formed by the relay wall 5 and the longitudinal pipe shed 7 needs to bear:

[0074] P=ξF 3

[0075] Where P is the residual sliding force that the load-bearing unit needs to bear; ξ is the distribution coefficient, which ranges from 0 to 1.

[0076] The load-bearing unit formed by the relay wall 5 and the longitudinal pipe shed 7 is simplified to a single-span statically indeterminate beam with fixed connections at both ends, and the limit disturbance of a single longitudinal pipe 3 under the action of the residual sliding force is calculated as follows:

[0077]

[0078] Where, q is the residual sliding force borne by a single longitudinal pipe 3; D is the layout spacing of the longitudinal pipes 3 of the longitudinal pipe rack 7; C is the layout range of the longitudinal pipe rack 7; w maxis the mid-span deflection of the longitudinal pipe shed 7; E is the elastic modulus of the longitudinal pipe shed 7; I is the section moment of inertia of the longitudinal pipe shed 7 and the grouting body.

[0079] The calculation formula for the mid-span deflection of the longitudinal pipe rack 7 is as follows:

[0080]

[0081] Wherein, L is the length of the longitudinal tube 3 between the relay walls 5.

[0082] The calculation formula for the cross-sectional inertia moment of the longitudinal pipe support 7 and the grouting body is as follows:

[0083]

[0084] Wherein, d is the diameter of a single longitudinal tube 3.

[0085] Step 3.3, calculate the maximum tensile stress of a single longitudinal tube 3 under the residual sliding force:

[0086]

[0087] In the formula, σ max is the maximum tensile stress borne by a single longitudinal tube 3;

[0088] The maximum tensile stress must be less than the allowable stress of the steel pipe. Taking a safety factor of 1.5, the allowable stress of the steel pipe is:

[0089] σ max ≤[σ]=235 / 1.5=156.7MPa.

[0090] Step 3.4, based on the calculation of the limit disturbance of a single longitudinal pipe 3 and the maximum tensile stress of a single longitudinal pipe 3, calculate the pipe shelf length L under the limit disturbance of a single longitudinal pipe 3 and the allowable stress condition respectively. 1 , L 2 ;

[0091]

[0092] Step 3.5, the length L of a single longitudinal tube 3 should be L 1 , L 2 the length L of a single longitudinal tube 3 is the spacing of the relay wall 5.

[0093] In order to verify the actual effect of the relay-type dark excavation shed tunnel structure system, the following actual engineering verification was carried out:

[0094] Taking a slope project as an example, the weight of the potential sliding soil mass in each part of the slope is G 1 =1495kN, G 2 =2392kN, G 3=2725.5kN,l 1 =21m,l 2 =11.69m,l 3 =9.47m, cohesion c=38kPa, friction angle Slope safety factor γ t =1.3.

[0095]

[0096] The layout range of the longitudinal pipe rack is 9.5m, the longitudinal pipe layout spacing of the longitudinal pipe rack is 0.4m, the diameter of a single longitudinal pipe is 0.108m, and the elastic modulus of the longitudinal pipe rack is E=95×10 4 MPa.

[0097] ① Substitute the relevant parameters into the formula to calculate the remaining sliding force F 3 :

[0098]

[0099] Calculate the remaining sliding force that the bearing unit formed by the relay wall and the longitudinal pipe shed needs to bear. Here, the distribution coefficient ξ=0.8 is conservatively taken:

[0100] P=ξF 3

[0101] =0.8×67.51

[0102] =54.01KN

[0103] ② Input the relevant parameters and calculate the residual sliding force q borne by a single pipe rack:

[0104]

[0105] ③ Input the relevant parameters to calculate the limit disturbance of a single longitudinal pipe and the pipe shelf length L under the allowable stress condition 1 , L 2 :

[0106]

[0107] From the above calculations, it can be seen that under the geological conditions, when the relay wall is set at no more than 14.31m, the relay-type dark excavation shed tunnel structure system can effectively isolate the disturbance of the shed tunnel to the slope, ensuring the stability of the shed tunnel and the mountain during the tunnel construction process.

[0108] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A relay-type dark excavation shed tunnel structure system, characterized in that: The relay-type dark excavation shed tunnel structure system includes a main tunnel structure, which adopts the following structure in the slope excavation section: The main tunnel structure includes a group of arc-shaped arch structures, which are arranged at intervals. A group of arc-shaped arches are connected by a number of longitudinal pipes on one side close to the slope body and connected by a special-shaped beam on the other side. A group of arc-shaped arches are arranged with a number of relay walls at intervals on one side close to the slope body, and the longitudinal pipe shed runs through the relay wall. A number of transverse steel pipe piles driven obliquely into the slope body are installed above the top of the special-shaped beam body. The transverse steel pipe piles are driven into the slope body and connected with the top of the special-shaped beam body to form an anchoring unit, through which the transverse upper side anchor of the main tunnel structure is realized; a plurality of longitudinal pipes form a longitudinal pipe rack, and the longitudinal pipe rack cooperates with the relay wall structure to form a longitudinal bearing unit, through which the lower side support of the main tunnel structure is realized when the excavation constraint of the rock and soil body is lost.

2. The relay-type dark excavation shed tunnel structure system according to claim 1 is characterized in that: The arc-shaped arch structure comprises a sleeve arch located at the outer circle of the arc-shaped arch structure, and a lining layer structure located at the inner circle and bottom of the arc-shaped arch structure.

3. The relay-type dark excavation shed tunnel structure system according to claim 1 is characterized in that: The cross section of the relay wall is a right-angled trapezoidal wall structure, one side of which extends into the main hole structure, and the other side is embedded in the slope body.

4. The relay-type dark excavation shed tunnel structure system according to claim 2 is characterized in that: The special-shaped beam body includes a plurality of inclined columns arranged at intervals along the excavation direction of the shed tunnel. A special-shaped supporting beam is installed on the top of the inclined column and a cap beam is installed on the bottom; the special-shaped supporting beam is connected to a group of circular arc arch structures and one side of the lining layer structure; the special-shaped beam body also includes a plurality of transverse connecting beams arranged at intervals along the excavation direction of the shed tunnel, and the cap beam is connected to the lining layer structure in the main tunnel structure through a plurality of transverse connecting beams.

5. The relay-type dark excavation shed tunnel structure system according to claim 4 is characterized in that: The special-shaped support beam is provided with a cap beam obliquely above the main tunnel structure. The cap beam is located on the mountain side of the center line of the cross section of the main tunnel structure, and the cap beam is connected to one end of the transverse steel pipe pile.

6. A construction method for a relay-type dark excavation shed tunnel structure system, the construction method is based on the shallow buried biased relay-type dark excavation shed tunnel structure according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: excavate the mountain in a small area, clear out the working platform, and drive transverse steel pipe piles into the mountain of the slope. The ends of the transverse steel pipe piles are cast together with the cap beam; Step 2, further excavate the mountain in a small area downwards, and construct the cap beam, inclined columns and special-shaped supporting beams; Step 3, calculate and determine the spacing and number of relay walls based on geological conditions and the length of the shed hole; Step 4: Determine the location of the relay wall based on the spacing and number of the relay walls, cast the relay wall after milling, reserve a guide pipe at a suitable position of the relay wall during the casting process, and ensure that the top of the relay wall has the same slope as the mountain surface; Step 5, construct a longitudinal pipe shed from the sleeve arch position to the relay wall, and the pipe shed passes through the relay wall; Step 6, excavating the main hole under the pipe shed and constructing the lining structure; Step 7: When the main tunnel structure is excavated to the relay wall, the part of the relay wall in the main tunnel is removed by milling and excavation according to the tunnel contour, and the longitudinal pipe shed is continued to be built from the reserved guide sleeve of the relay wall to the next relay wall; Step 8, continue to excavate the main hole under the pipe shed; repeat the above steps until the main hole is connected; when setting up the longitudinal pipe shed, its upper elevation angle is 1 to 3 degrees, so that the longitudinal pipes form an arch as a whole.

7. The construction method of the relay-type dark excavation shed tunnel structure system according to claim 6 is characterized in that: In step 3, the spacing of the relay walls is determined as follows: Step 3.1, calculate the remaining sliding force of the slope: Where F1, F2, and F3 are the residual sliding forces of each part of the slope, among which F1 represents the first section of the slope, F2 represents the middle section of the slope, and F3 represents the tail end of the slope close to the main tunnel structure; γ t is the safety factor; G1, G2, G3 are the weights of the potential sliding soil at each part of the slope; θ1, θ2, θ3 are the angles between the potential sliding soil at each part of the slope and the horizontal plane; is the internal friction angle of each part of the slope; c1, c2, c3 are the cohesion of the rock and soil in each part of the slope; l1, l2, l3 are the potential sliding lengths of the soil in each part of the slope; ψ2, ψ3 are the load transfer coefficients between slopes, Step 3.2, calculate the remaining sliding force that the bearing unit formed by the relay wall and the longitudinal pipe roof needs to bear: Where P is the residual sliding force that the load-bearing unit needs to bear; ξ is the distribution coefficient; The load-bearing unit formed by the relay wall and the longitudinal pipe shed is simplified into a single-span statically indeterminate beam with fixed connections at both ends. The limit disturbance of a single longitudinal pipe under the action of the residual sliding force is calculated as follows: Where q is the residual sliding force on a single longitudinal pipe; D is the longitudinal pipe layout spacing of the longitudinal pipe rack; C is the layout range of the longitudinal pipe rack; w max is the mid-span deflection of the longitudinal pipe shed; L is the length of the longitudinal pipe between the relay walls; E is the elastic modulus of the longitudinal pipe shed; I is the section moment of inertia of the longitudinal pipe shed and the grouting body; d is the diameter of a single longitudinal pipe; Step 3.3, calculate the maximum tensile stress of a single longitudinal tube under the residual sliding force: In the formula, σ max is the maximum tensile stress of a single longitudinal tube; Step 3.4, based on the calculation of the limit disturbance of a single longitudinal pipe and the maximum tensile stress of a single longitudinal pipe, respectively calculate the pipe shelf lengths L1 and L2 under the limit disturbance of a single longitudinal pipe and the allowable stress conditions; Step 3.5, the length L of a single longitudinal tube should be the smaller of L1 and L2; the length L of a single longitudinal tube is the spacing of the relay walls.

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