A combined water-draining segment for high-water-pressure TBM tunnels and its design method

Abstract

The present invention discloses a combined water-draining segment for a high-water-pressure TBM tunnel, comprising a combined segment, a deep hole located at the arch foot of the combined segment, and a drainage hole located between the arch waist and the arch crown of the combined segment. The combined segment is formed into an annular structure by splicing a capping block, a bilaterally symmetrical collar block, and a standard block end to end. The present invention also discloses a design method for a combined water-draining segment for a high-water-pressure TBM tunnel, comprising the following steps: Step S1, determining the circumferential opening angle θ of the deep hole; dh and the length L of the pinhole drain pipe dh Step S2: Determine the annular spacing angle Δθ of the drain holes h and the number of rows of drainage holes along the longitudinal direction of the joint segment n y ; Step S3, estimate the δ value of the drainage hole and preliminarily judge the rationality of the design parameters of the drainage hole on the joint pipe segment; Step S4, process the data to generate the ν‑θ variation curve of the joint pipe segment, which has the advantages of stable joint pipe segment structure, large discharge flow, good pressure reduction effect, and accurate design parameters.

Description

Technical Field

[0001] The present invention belongs to the technical field of water discharge and pressure reduction in high-pressure TBM tunnels, and particularly relates to a high-pressure TBM tunnel combined water discharge type segment and a design method. Background Art

[0002] TBM tunnel construction in high-pressure, water-rich areas often faces the problem of engineering safety hazards due to the excessive external water pressure on the lining of the segments. However, the external water pressure on the lining can be effectively reduced by designing the drainage of the segments. Deep hole drainage segments or drainage hole drainage segments are usually used.

[0003] However, the deep-hole drainage method, which involves adding pin-hole drainage pipes around the circumference of the segment to relieve water and reduce pressure, has the characteristics of large single-hole discharge and significant single-hole pressure reduction effect. However, it also has the problem of excessive loss of groundwater resources, which leads to the destruction of the groundwater environmental balance. The drainage hole drainage method, which involves opening drainage holes around the segment to relieve water and reduce pressure, has the characteristics of small single-hole discharge and a small single-hole pressure reduction range. It usually requires a relatively dense layout of drainage holes to achieve the ideal pressure reduction effect, resulting in reduced stability of the segment structure. At the same time, the drainage type segment can only be based on three standard types: circumferential single-opening drainage type, circumferential double-opening drainage type, and circumferential triple-opening drainage type. These are roughly selected according to the tunnel construction site, resulting in the segment not being fully adapted to the tunnel site. Summary of the Invention

[0004] Based on the concept of "tunnel engineering and groundwater environmental balance", the present invention studies the influence of the design parameters of drainage hole drainage and deep hole drainage on the external water pressure of the segment lining, the drainage flow and the stable water level drop, and proposes a new drainage segment design method based on drainage hole + deep hole combined drainage, which has a large drainage flow, good pressure reduction effect and strong structural stability. It solves the problems of excessive loss of groundwater resources and destruction of groundwater environmental balance due to the use of deep hole drainage segment, and the reduced stability of the segment structure due to dense arrangement of holes in the drainage hole drainage segment.

[0005] To this end, the technical solution adopted by the present invention is: a high-water-pressure TBM tunnel combined drainage type pipe segment, including a combined pipe segment, a deep hole located at the arch foot of the combined pipe segment, and a drainage hole located between the arch waist and the arch top of the combined pipe segment. The combined pipe segment is formed by splicing a capping block, a left-right symmetrical collar block, and a standard block end to end to form a ring structure. The deep holes and the drainage holes are arranged symmetrically in a ring on the combined pipe segment, and the deep holes are connected to a pin hole drainage pipe extending outward.

[0006] As a preferred embodiment of the above scheme, the outer diameter of the combined segment is 8300mm to 8400mm, the wall thickness is 400mm to 500mm, and the ring width is 1800mm to 2000mm, which meets the size requirements of conventional tunnels and has a reasonable design.

[0007] It is further preferred that the bottom of the joint segment and the excavated gap within a 90° central angle are filled with C20 early-strength fine stone concrete, and other areas are filled with blown pea-grain stone and injected with cement slurry, so as to fully ensure the stability of the joint segment installation while reducing the installation cost.

[0008] More preferably, the pin hole drain pipe length L dh =0.25d g , d g is the thickness of the grouting ring, which is half of the inner diameter of the tunnel. The formula is reasonable.

[0009] The present invention also provides a method for designing a combined water-draining segment for a high-water-pressure TBM tunnel, comprising the following steps:

[0010] Step S1: Using the aforementioned high-pressure TBM tunnel combined-type drainage segment, the overburden pressure, water head height, permeability coefficient, and combined segment size-related parameters are determined based on actual tunnel engineering conditions. A software model is used to perform fluid-solid coupling calculations and parameter analysis under different deep-hole drainage patterns. The evolution characteristics of the external water pressure on the segment lining, the segment discharge flow, and the stable water level drawdown are studied, thereby determining the circumferential opening angle θ of the deep hole. dh and the length L of the pinhole drain pipe dh ;

[0011] Step S2: Perform fluid-solid coupling calculation and parameter analysis under different drainage hole drainage patterns through software models, study the evolution characteristics of water pressure outside the segment lining, segment discharge, and stable water level drawdown, and determine the annular spacing angle Δθ of the drainage holes. h and the number of rows of drainage holes along the longitudinal direction of the joint segment n y ;

[0012] Step S3: Based on the individual circumferential spacing angles Δθ h The combined pressure reduction degree δ of the drainage holes in the 45° annular three-opening drainage type segment is δ, where δ is the ratio of the lining external water pressure to the limit and θ h1 ~θ h2 Within the range max The difference is calculated by dividing the circumferential spacing angle Δθ of the water leakage holes obtained in step S2. h Compared with 45°, estimate the δ value of the drain hole. When the δ value is greater than 0, the number of columns n is selected. y It is reasonable to enhance the blood pressure reduction effect. When the δ value is less than 0, the number of columns n is selected. yIt is reasonable only if it can avoid excessive pressure reduction, thus preliminarily judging the rationality of the design parameters of the drainage holes on the joint pipe segment;

[0013] Step S4: Install the designed joint segment in the tunnel, perform fluid-solid coupling calculations on the tunnel, extract the water pressure value outside the circumferential lining of the joint segment, and process the data to generate a ν-θ variation curve for the joint segment. It is determined whether the water pressure value in the actual environment has dropped to a safe range, thereby accurately determining whether the parameter design of the deep holes and drainage holes on the joint segment meets the standards under the actual tunnel environment.

[0014] As a preferred embodiment of the above scheme, the method further includes step S5, comparing all the joint segments that meet the requirements of steps S1-S4 but have different design parameters to obtain the optimal design parameters, and then calculating the optimal design parameters by combining the pressure reduction angle θ / 180° of the joint segment with the discharge flow limit ratio Q / Q. lim The ratio λ between them is used for evaluation. The joint segment with the largest ratio λ is the optimal design parameter, which makes it easy to compare the optimal solution and achieve the best drainage effect of the joint segment.

[0015] More preferably, the circumferential opening angle θ of the deep hole is dh =46.41°. Based on the actual tunnel engineering conditions, the relevant parameters of cover pressure, water head height, permeability coefficient, and joint segment size are determined to obtain the optimal circumferential opening angle.

[0016] More preferably, the number of rows n of the drain holes along the longitudinal direction of the joint segment is y =2, the spacing between adjacent rows is 0.5m~0.7m, and the circumferential spacing angle Δθ h =51°, opening angle θ h1 =102.66°,θ h2 =156.09°, which meets the design criteria of the above steps S1-S4.

[0017] More preferably, the number of rows n of the drain holes along the longitudinal direction of the joint segment is y =1, and the circumferential spacing angle Δθ h =34°, opening angle θ h1 =97.03°、θ h2 =130.78,θ h3 =164.53°, which meets the design criteria of the above steps S1-S4.

[0018] Beneficial effects of the present invention:

[0019] (1) It effectively overcomes the defects of the pure deep hole drainage type, that is, the deep holes arranged around the pipe segments result in excessive leakage and the groundwater cannot be discharged in time through the deep holes on the upper part of the pipe segments, and the external water pressure of the lining on the upper part of the pipe segments cannot be reduced to the safe range, forming a vicious cycle. It effectively overcomes the defect of the pure drainage hole drainage type pipe segments, that is, the need for many drainage holes to control the external water pressure of the pipe segment lining, which leads to the instability of the pipe segment lining structure. The present invention comprehensively considers the circumferential pressure reduction range and leakage rate of the pipe segments, and cleverly combines the deep holes and drainage holes for drainage. The design is exquisite, the combined pipe segment structure is stable, and the leakage rate is large.

[0020] (2) The combined segment controls the external water pressure of the lining in the lower area of the segment by arranging deep holes in the arch foot area, and at the same time controls the external water pressure of the lining in the upper area of the segment by arranging a certain number of drainage holes between the arch waist and the arch crown. The groundwater near the deep holes can be quickly discharged through the drainage ditches on both sides of the inverted arch, and the groundwater in the upper area of the segment can also be diverted and discharged through multiple drainage holes, which greatly reduces the risk of water accumulation in the upper lining and has a good pressure reduction effect.

[0021] (3) First, the software model is used to perform fluid-solid coupling calculation and parameter analysis under different drainage hole discharge patterns, as well as fluid-solid coupling calculation and parameter analysis under different deep hole drainage patterns. The calculation is convenient and fast. Combined with the actual site of the tunnel, it effectively ensures the accuracy of the design parameters of the joint segment, reduces the workload, and avoids the mismatch between the parameter design of the deep hole and the drainage hole of the joint segment and the actual situation, as well as the unsatisfactory matching between the parameters and the site requirements caused by a single selection.

[0022] In summary, the combined segment structure has the advantages of stable structure, large discharge flow, good pressure reduction effect and precise design parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the cross section of design type A.

[0024] Figure 2 A schematic cross-sectional view of design B.

[0025] Figure 3 For different n y ν-θ variation curve (Δθ h =45°).

[0026] Figure 4 is the ν-θ variation curve of the joint segment (Δθ h =45°). DETAILED DESCRIPTION

[0027] The present invention will be further described below by way of examples and in conjunction with the accompanying drawings:

[0028] Combine Figure 1 — Figure 4As shown, a high-water-pressure TBM tunnel combined drainage segment consists of a combined segment 1, a deep hole 2 located at the arch foot of the combined segment 1, and a drainage hole 3 located between the arch waist and the arch crown of the combined segment 1.

[0029] The joint segment 1 is formed into a ring structure by splicing the capping block 11, the bilaterally symmetrical collar blocks 12 and the standard blocks 13 end to end.

[0030] The bottom of the joint segment 1 and the excavation gap within the 90° central angle are filled with C20 early-strength fine stone concrete, and other areas are filled with blown pea-grain stone and injected with cement slurry.

[0031] The outer diameter of the joint segment 1 is preferably 8300 mm to 8400 mm, the wall thickness is preferably 400 mm to 500 mm, and the ring width is preferably 1800 mm to 2000 mm.

[0032] The deep holes 2 and the drainage holes 3 are symmetrically arranged in a circular array on the joint pipe segment 1. The circular array means that they are arranged in rows around the circumference.

[0033] The deep hole 2 is connected to a pin hole drainage pipe 21 extending outward.

[0034] Pin hole drain pipe 21 length L dh =0.25d g , d g is the thickness of the grouting ring, which is half of the inner diameter of the tunnel.

[0035] A design method for a combined water-draining segment for a high-water-pressure TBM tunnel is implemented in the following steps:

[0036] Step S1: Using a high-pressure TBM tunnel combined drainage segment as described in any one of claims 1-4, determining the overburden pressure, water head height, permeability coefficient, and combined segment 1 size-related parameters based on actual tunnel engineering conditions.

[0037] Through the software model, fluid-solid coupling calculation and parameter analysis under different deep hole 2 discharge modes are carried out to study the evolution characteristics of the water pressure outside the segment lining, the segment discharge flow, and the stable water level drop, so as to determine the circumferential opening angle θ of deep hole 2. dh and the length L of the pin hole drain pipe 21 dh .

[0038] Step S2: Perform fluid-solid coupling calculation and parameter analysis under different drainage patterns of the drainage holes 3 through the software model, study the evolution characteristics of the water pressure outside the segment lining, the segment discharge, and the stable water level drop, and determine the annular spacing angle Δθ of the drainage holes 3. h and the number of rows n of drain holes 3 along the longitudinal direction of the joint segment 1 y .

[0039] Regarding the fluid-solid coupling calculation and parameter analysis performed by the software model in steps S1 and S2, considering that the influence area of groundwater seepage is large, the distance between the side wall of the tunnel hole and the model boundary is about 20 times the hole diameter. To improve the efficiency of fluid-solid coupling analysis, two rings of segments are taken longitudinally in the numerical model for analysis. The width of one ring of segments is 1.8m. The top of the model is the groundwater level line, the TBM tunnel head height is 250m, the overburden pressure is 3.3MPa, and the overall model dimensions are x=350m, y=3.6m, and z=350m.

[0040] The model's mechanical boundary conditions are: constraining the x-direction displacement of the left and right sides of the model, constraining the y-direction displacement of the front and back of the model, and constraining the x, y, and z-directions of the bottom surface of the model. The model's seepage boundary conditions are: the top surface of the model is a free permeable surface with an initial pore water pressure of 0; the left and right sides of the model are constant head boundaries, with pore water pressure varying linearly with height; the bottom surface of the model is an impermeable boundary; after tunnel excavation, the inner surface of the rough hole is a free seepage boundary; after segmental lining installation, the inner surface of the drain port is a free seepage boundary; when performing seepage analysis using finite element software, the pore water pressure at each free seepage boundary should be set to 0.

[0041] Thus, two types of design of joint segments 1 are obtained.

[0042] The design parameters of design type A are: the circumferential opening angle θ of deep hole 2 dh =46.41°, the number of rows of drain holes 3 along the longitudinal direction of the joint segment 1 is n y =2, the spacing between adjacent rows is 0.5m~0.7m, and the circumferential spacing angle Δθ h =51°, opening angle θ h1 =102.66°,θ h2 =156.09°.

[0043] The design parameters of design type B are: the circumferential opening angle θ of deep hole 2 dh =46.41°, the number of rows of drain holes 3 along the longitudinal direction of the joint segment 1 n y =1, and the circumferential spacing angle Δθ h =34°, opening angle θ h1 =97.03°、θ h2 =130.78,θ h3 =164.53°.

[0044] Step S3: Based on the individual circumferential spacing angles Δθ h The combined pressure reduction degree δ of the drainage holes in the 45° annular three-opening drainage type segment is δ, where δ is the ratio of the lining external water pressure to the limit and θ h1 ~θ h2 Within the range max The difference, such as Figure 3 shown.

[0045] The maximum total pressure reduction angle of the circumferential single-opening drainage type is 35.01°, and the maximum total pressure reduction angle of the circumferential double-opening drainage type is 78.01°. The total pressure reduction angles of these two drainage hole drainage types are both less than 102°, which cannot meet the design requirements of the new combined drainage type segment. The minimum total pressure reduction angle of the circumferential three-opening drainage type is 81.13°, and the maximum total pressure reduction angle reaches 132.19°. Therefore, the design parameters of the drainage holes in the new combined drainage type segment can be selected and optimized based on the circumferential three-opening drainage type.

[0046] By calculating the circumferential spacing angle Δθ of the drain holes 3 obtained in step S2 h Compared with 45°, estimate the δ value of drain hole 3. When the δ value is greater than 0, the number of columns n is selected. y It is reasonable to enhance the blood pressure reduction effect. When the δ value is less than 0, the number of columns n is selected. y It is reasonable to avoid excessive pressure reduction, thereby preliminarily judging the rationality of the design parameters of the drainage hole (3) on the joint pipe segment (1).

[0047] Based on the reference type Δθ h = 45° is used as a reference indicator, as shown in the following table:

[0048] Drain hole design type judgment table

[0049]

[0050]

[0051] From the above table, we can conclude that: the circumferential spacing angle Δθ in design type A h >45°, indicating that the combined pressure reduction effect between holes is worse than that of the reference type. Therefore, the δ value should be greater than 0 to enhance the pressure reduction effect. y =2 is more reasonable; the annular spacing angle Δθ in design type B h <45°, indicating that the combined pressure reduction effect between holes is stronger than that of the reference type. At this time, the δ value should be less than 0 to avoid excessive pressure reduction, so n is selected. y =1 is more reasonable.

[0052] Step S4: Install the designed joint segment 1 in the tunnel, perform fluid-solid coupling calculation on the tunnel, extract the water pressure value outside the circumferential lining of the joint segment 1, and process the data to generate a ν-θ variation curve of the joint segment 1.

[0053] Specific as Figure 4 As shown, it is determined whether the water pressure value in the actual environment has dropped to a safe range, thereby accurately determining whether the parameter designs of the deep hole 2 and the drainage hole 3 on the joint segment 1 in the actual tunnel environment meet the standards.

[0054] Step S5: Compare all the joint segments 1 that meet the requirements of steps S1-S4 but have different design parameters to obtain the optimal design parameters. lim The joint segment 1 with the largest ratio λ is evaluated by the ratio λ between them, and the optimal design parameters are obtained.

[0055] The design parameters of the joint segment 1 of design type A in accordance with steps S1-S4 are: the circumferential opening angle θ of the deep hole 2 dh =46.41°, the number of rows of drain holes 3 along the longitudinal direction of the joint segment 1 n y =2, the spacing between adjacent rows is 0.5m~0.7m, and the circumferential spacing angle Δθ h =51°, opening angle θ h1 =102.66°,θ h2 =156.09°.

[0056] The design parameters of the joint segment 1 of design type B in accordance with steps S1-S4 are: the circumferential opening angle θ of the deep hole 2 dh =46.41°, the number of rows of drain holes 3 along the longitudinal direction of the joint segment 1 n y =1, and the circumferential spacing angle Δθ h =34°, opening angle θ h1 =97.03°、θ h2 =130.78,θ h3 =164.53°.

[0057] Compare the pressure reduction angle θ / 180° and the discharge flow limit ratio Q / Q of the joint segment 1 of design type A and design type B lim The ratio λ between them is shown in the following table:

[0058] λ value calculation table for two types of combined segments

[0059]

[0060] Discharge limit ratio Q / Q of joint segment of design type A lim It is 11.20% smaller than the joint segment of design type B, and the λ value is 12.61% larger than the joint segment of design type B. Therefore, under the premise of comprehensively considering the pressure reduction range and discharge flow, the design of the joint segment of design type A is relatively better.

Claims

1. A method for designing a combined water-draining segment for a high-water-pressure TBM tunnel, characterized in that: The following steps are involved: Step S1, using a high-pressure TBM tunnel combined type drainage type segment, the high-pressure TBM tunnel combined type drainage type segment comprising a combined segment (1), a deep hole (2) located at the arch foot of the combined segment (1), and a drainage hole (3) located between the arch waist and the arch crown of the combined segment (1); the combined segment (1) is formed by splicing a capping block (11), a left-right symmetrical collar block (12), and a standard block (13) end to end to form a ring structure; the deep hole (2) and the drainage hole (3) are arranged symmetrically on the combined segment (1) in a ring; the deep hole (2) is connected to a pin hole drainage pipe (21) extending outward; Based on the actual tunnel engineering conditions, the backfill pressure, water head height, permeability coefficient, and the size of the joint segment (1) are determined. The fluid-solid coupling calculation and parameter analysis under different deep hole (2) discharge modes are carried out through the software model. The evolution characteristics of the water pressure outside the segment lining, the segment discharge flow, and the stable water level drop are studied, so as to determine the circumferential opening angle of the deep hole (2). θ dh and the length of the pinhole drain pipe (21) L dh ; Step S2: Use software models to perform fluid-solid coupling calculations and parameter analysis under different drainage patterns of drainage holes (3), study the evolution characteristics of the water pressure outside the segment lining, the drainage flow of the segment, and the stable water level drop, and determine the annular spacing angle ∆ of the drainage holes (3). θ h and the number of rows of drain holes (3) along the longitudinal direction of the joint segment (1) n y ; Step S3: Based on the individual circumferential spacing angle ∆ θ h The combined pressure reduction degree of the drainage holes in the 45° annular three-opening drainage type segment δ , δ is the lining external water pressure limit ratio and θ h1 ~ θ h2 Within range ν max The difference, θ h1 is the opening angle of the first drain hole, θ h2 is the opening angle of the second drain hole, θ h1 ~ θ h2 The range value from the first drain hole opening angle to the second drain hole opening angle, ν max is the maximum limit ratio of the external water pressure of the lining; By calculating the annular spacing angle ∆ of the drain hole (3) obtained in step S2 θ h Compared with 45°, the estimated δ value, δ When the value is greater than 0, the number of rows of drain holes (3) along the longitudinal direction of the joint segment (1) n y Need to enhance the antihypertensive effect, δ When the value is less than 0, the number of rows of drain holes (3) along the longitudinal direction of the joint segment (1) n y It is necessary to avoid excessive pressure reduction, so as to preliminarily judge the rationality of the design parameters of the drainage hole (3) on the joint segment (1); Step S4: Install the designed joint segment (1) in the tunnel, perform fluid-solid coupling calculation on the tunnel, extract the water pressure value outside the annular lining of the joint segment (1), and process the data to generate the joint segment (1) ν-θ Change curve, ν is the limit ratio of the external water pressure of the segmental lining, θ The circumferential angle of the segment is used to determine whether the water pressure value in the actual environment has dropped to a safe range, thereby accurately determining whether the parameter design of the deep hole (2) and the drainage hole (3) on the combined segment (1) in the actual tunnel environment has met the standards.

2. The method for designing a combined water-draining segment for a high-water-pressure TBM tunnel according to claim 1, characterized in that: The outer diameter of the joint segment (1) is 8300 mm to 8400 mm, the wall thickness is 400 mm to 500 mm, and the ring width is 1800 mm to 2000 mm.

3. The method for designing a combined water-draining segment for a high-water-pressure TBM tunnel according to claim 1, characterized in that: The bottom of the joint segment (1) and the excavated gap within the range of 90° of the central angle are filled with C20 early strength fine stone concrete, and the other areas are filled with blown pea-grain stone and injected with cement slurry.

4. The method for designing a combined water-draining segment for a high-water-pressure TBM tunnel according to claim 1, characterized in that: The length of the pin hole drain pipe (21) L dh =0.25 d g , d g is the thickness of the grouting ring, which is half of the inner diameter of the tunnel.

5. The method for designing a combined water-draining segment for a high-water-pressure TBM tunnel according to claim 1, characterized in that: The method further includes step S5, comparing all the joint segments (1) that meet the requirements of steps S1-S4 but have different design parameters to obtain the optimal design parameters, and then determining the pressure reduction angle of the joint segment (1). θ / 180° and leakage flow limit ratio Q / Q lim The ratio between λ To evaluate, the ratio λ The largest joint segment (1) is the optimal design parameter.

6. The method for designing a combined water-draining segment for a high-water-pressure TBM tunnel according to claim 1, characterized in that: The circumferential opening angle of the deep hole (2) θ dh =46.41°.

7. The method for designing a combined water-draining segment for a high-water-pressure TBM tunnel according to claim 6, characterized in that: The number of rows of the drainage holes (3) along the longitudinal direction of the joint segment (1) n y =2, the distance between adjacent rows is 0.5m~0.7m, and the circumferential spacing angle ∆ θ h =51°, opening angle θ h1 =102.66°, θ h2 =156.09°.

8. The method for designing a combined water-draining segment for a high-water-pressure TBM tunnel according to claim 6, characterized in that: The number of rows of the drainage holes (3) along the longitudinal direction of the joint segment (1) n y =1, and the circumferential spacing angle ∆ θ h =34°, opening angle θ h1 =97.03°, θ h2 =130.78°, θ h3 =164.53°.

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