Method for determining fortification parameters of partial secondary lining of TBM diversion tunnel and construction method thereof

Abstract

The application provides a TBM water diversion tunnel local secondary lining fortification parameter determination method and a construction method thereof, comprising: establishing a three-dimensional fluid-solid coupling calculation model corresponding thereto; obtaining the pore water pressure situation, deformation situation, maximum principal stress distribution situation, minimum principal stress distribution situation and tunnel body water inflow situation behind the initial support structure of the tunnel under the condition that the secondary lining is not constructed under the surrounding rock condition; determining the influence range value of the fault fracture zone on the tunnel under the surrounding rock condition, and obtaining the initial value of the length of the local secondary lining beyond the two ends of the fault fracture zone; determining the optimal value of the local secondary lining fortification parameter under the current working condition; performing regression analysis on the optimal value of the local secondary lining fortification parameter under the current working condition, and obtaining the fortification length of the local secondary lining beyond the two ends of the fault fracture zone and the thickness of the local secondary lining, and the change relationship formula of the length of the fault fracture zone and the surrounding rock grade on the left and right sides of the fault.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for determining the design parameters and construction method of a TBM water diversion tunnel crossing a water-rich fault with a local secondary lining. Background Technology

[0002] As hydraulic tunnel projects develop towards greater depth, length, and size, they inevitably traverse different geological sections, leading to significant changes in rock mass properties and increasing the probability of adverse geological problems. Many water diversion tunnels traverse strata dominated by Class II and Class III surrounding rock, offering favorable conditions for tunnel construction. TBMs are commonly used, and most tunnel sections require only initial support with shotcrete. However, when hydraulic tunnels cross fault fracture zones, the combined action of the fault fracture zone and groundwater can trigger geological disasters such as water inrush and mudslides, and even collapses, severely impacting construction safety and progress. Existing solutions typically involve grouting reinforcement of the fault fracture zone or using waterproof concrete and waterproof layers in the secondary lining. However, grouting reinforcement rings may not withstand the high surrounding rock stresses at fault fracture zones in deeply buried tunnels; and secondary lining along the entire tunnel length is not economically viable for long-distance hydraulic tunnel projects.

[0003] To ensure safety during construction and operation, and to block water in the fault fracture zone, the tunnel is protected by partial secondary lining when crossing water-rich faults. Summary of the Invention

[0004] This invention provides a method for determining the design parameters of a partial secondary lining for a TBM water diversion tunnel and a construction method thereof, comprising the following steps:

[0005] Step 1: Establish a three-dimensional fluid-structure interaction calculation model II based on the parameters of the tunnel traversing Class II surrounding rock and a three-dimensional fluid-structure interaction calculation model I based on the parameters of the tunnel traversing Class I surrounding rock.

[0006] Step 2: Numerical simulations of the seepage field, surrounding rock deformation field, and stress field around the tunnel during the tunnel crossing the fault fracture zone are performed using the three-dimensional fluid-structure interaction calculation model II and the three-dimensional fluid-structure interaction calculation model I, respectively. This is to obtain the pore water pressure, deformation, maximum principal stress distribution, minimum principal stress distribution, and tunnel water inflow behind the initial support structure of the tunnel when the tunnel crosses Class II surrounding rock and when the tunnel crosses Class I surrounding rock without secondary lining.

[0007] Step 3: Based on the pore water pressure, deformation, maximum principal stress distribution, minimum principal stress distribution, and tunnel inflow of the initial support structure of the tunnel under the conditions of Class II surrounding rock and Class I surrounding rock without secondary lining, determine the influence range of the fault fracture zone on the tunnel under the conditions of Class II surrounding rock and Class I surrounding rock, respectively.

[0008] Step 4: Based on the determined influence range of the fault fracture zone on the tunnel, obtain the initial value of the length L1 of the local secondary lining extending beyond one end of the fault fracture zone and the initial value of the length L2 of the local secondary lining extending beyond the other end of the fault fracture zone.

[0009] Step 5: Numerical simulations of the seepage field characteristics, surrounding rock deformation, maximum principal stress, and minimum principal stress around the tunnel after partial secondary lining are performed using three-dimensional fluid-structure interaction calculation model II and three-dimensional fluid-structure interaction calculation model I, respectively. This is to obtain the maximum values ​​of pore water pressure, deformation, maximum principal stress, minimum principal stress, and tunnel inflow behind the tunnel lining structure after partial secondary lining are performed when the tunnel passes through Class II surrounding rock and Class I surrounding rock, respectively. The maximum values ​​of pore water pressure, deformation, maximum principal stress, minimum principal stress, and tunnel inflow behind the tunnel lining structure after partial secondary lining are used as analysis indicators to determine the optimal values ​​of the local secondary lining design parameters under the current working conditions.

[0010] Step 6: Perform regression analysis on the optimal values ​​of the local secondary lining design parameters under the current working conditions to obtain the design length of the local secondary lining extending beyond both ends of the fault fracture zone and the relationship between the thickness of the local secondary lining and the length of the fault fracture zone and the grade of the surrounding rock on the left and right sides of the fault.

[0011] Optionally, the parameters for the tunnel traversing Class II surrounding rock and the parameters for the tunnel traversing Class I surrounding rock include the mechanical parameters, seepage parameters, design parameters of the tunnel cross-section, and the length L of the fault fracture zone of the surrounding rock and fault fracture zone traversed by the tunnel.

[0012] Optionally, in step three, the specific method for determining the influence range of the fault fracture zone on the tunnel when the tunnel passes through Class II surrounding rock and when the tunnel passes through Class I surrounding rock is as follows:

[0013] Let A1 be the range of influence of the fault fracture zone on the tunnel determined by the pore water pressure behind the initial support structure of the tunnel without secondary lining, A2 be the range of influence of the fault fracture zone on the tunnel determined by the deformation behind the initial support structure of the tunnel without secondary lining, A3 be the range of influence of the fault fracture zone on the tunnel determined by the maximum principal stress distribution behind the initial support structure of the tunnel without secondary lining, A4 be the range of influence of the fault fracture zone on the tunnel determined by the minimum principal stress distribution behind the initial support structure of the tunnel without secondary lining, and A5 be the range of influence of the fault fracture zone on the tunnel determined by the water inflow of the tunnel body without secondary lining. Calculate the union of A1, A2, A3, A4, and A5. The union obtained is the range of influence of the fault fracture zone on the tunnel.

[0014] Optionally, in step five, the specific method for determining the optimal value of the local secondary lining design parameters under the current working condition is as follows:

[0015] The maximum values ​​of L1 and L2 are reduced from their maximum values ​​to 0 at intervals of 1m, so as to obtain the maximum pore water pressure, maximum deformation, maximum principal stress, maximum minimum principal stress and maximum water inflow of the tunnel body behind the tunnel lining structure after the local secondary lining is applied when the maximum values ​​of L1 and L2 are different.

[0016] Meanwhile, as the maximum values ​​of the length L1 of the local secondary lining extending beyond one end of the fault fracture zone and the maximum value of the length L2 of the local secondary lining extending beyond the other end of the fault fracture zone are gradually reduced, when a sudden change occurs in one of the analytical indicators, the length L of the local secondary lining extending beyond the fault fracture zone at the time of the sudden change is obtained. i The value and the length L of the local secondary lining extending beyond the other end of the fault fracture zone. p If the value is L, then L will be L. i The previous set of values ​​L i-1 Value and L p The previous set of values ​​L p-1 The value is taken as the optimal length of the local secondary lining extending beyond both ends of the fault fracture zone under the current working conditions.

[0017] Optionally, in step six, the expressions for the relationship between the fortification lengths L1′ and L2′ of the local secondary lining extending beyond both ends of the fault fracture zone and the thickness d of the local secondary lining as a function of the fault fracture zone length L and the grade of the surrounding rock on the left and right sides of the fault are as follows:

[0018]

[0019] K1, K2, B1, and B2 are model coefficients, whose values ​​are related to the length of the fault fracture zone and the surrounding rock grade on both sides of the fault.

[0020] Optionally, when the surrounding rock grade on both sides of the fault is Class II and the local secondary lining thickness d is 30cm-50cm, the value of K1 is 0.31-0.15, the value of K2 is 0.21-0.13, the value of B1 is 1.16-2.35, and the value of B2 is 1.26-1.88.

[0021] When the surrounding rock grade on both sides of the fault is Class I and the local secondary lining thickness d is 30cm-50cm, the values ​​of K1 are 0.28-0.39, K2 are 0.18-0.26, B1 are 0.15-0.48, and B2 are 0.36-0.90.

[0022] Optionally, when the surrounding rock grade on both sides of the fault is Class II and the local secondary lining thickness d is 30cm, 40cm or 50cm, the values ​​of K1 are 0.31, 0.21 or 0.15, K2 are 0.21, 0.16 or 0.13, B1 are 1.16, 2.01 or 2.35, and B2 are 1.26, 1.66 or 1.88.

[0023] When the surrounding rock grade on both sides of the fault is Class I and the local secondary lining thickness d is 30cm, 40cm or 50cm, the values ​​of K1 are 0.39, 0.34 or 0.28, K2 is 0.26, 0.24 or 0.18, B1 is 0.19, 0.15 or 0.48, and B2 is 0.36, 0.51 or 0.90.

[0024] This invention also provides a construction method for partial secondary lining of a TBM water diversion tunnel, comprising the following steps:

[0025] Step 1: Preparations before construction:

[0026] The design parameters for the local secondary lining of the TBM water diversion tunnel are determined using the method described above.

[0027] Based on the determined design thickness d of the secondary lining under the surrounding rock conditions, and based on the local secondary lining design thickness d, the design length L1′ of one end of the local secondary lining and the design length L2′ of the other end of the local secondary lining are calculated according to the length L of the fault fracture zone through which the tunnel passes. Based on the design length L1′ of one end of the local secondary lining and the design length L2′ of the other end of the local secondary lining, the design length L of the local secondary lining is calculated. S , where L S =L1′+L2′;

[0028] Construction orientation measurements were taken for the location of the local secondary lining, and the formwork for the bottom slab was erected.

[0029] Step 2, Concrete construction;

[0030] Step 3: Fabrication and installation of reinforcing bars;

[0031] Step 4: Template installation;

[0032] Step 5: Jointing of reinforced concrete lining;

[0033] Step 6: Inventory clearance and acceptance;

[0034] Step 7: Concrete pouring;

[0035] Step 8: Demolding.

[0036] Optionally, the local secondary lining protection parameters include the construction range and thickness of the local secondary lining.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) When the relationship between the design parameters of the local secondary lining of the tunnel crossing the water-rich fault and the strength of the surrounding rock and the fault length is not clear and the local secondary lining construction cannot be carried out, the design parameter determination method of the local secondary lining of the TBM water diversion tunnel provided by the present invention has guiding significance for the determination of the design parameters of related projects by the relationship between the design length and thickness of the local secondary lining and the fault thickness and the grade of the surrounding rock on the left and right sides of the fault.

[0039] (2) Compared with the traditional construction process of tunnels crossing water-rich faults, the construction method of TBM water diversion tunnel with partial secondary lining provided by the present invention adopts partial secondary lining for protection when crossing water-rich faults. The partial secondary lining can not only withstand the extremely high surrounding rock stress at the fault, but also improve the seepage prevention ability of the lining structure, which greatly enhances the stability and safety of the tunnel when crossing water-rich fault strata.

[0040] (3) In this invention, by adopting a construction process of partial secondary lining and determining its design parameters, it has better economic benefits than constructing secondary lining along the entire length of the tunnel.

[0041] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0042] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0043] Figure 1 This is a schematic diagram of the defense parameters in this invention;

[0044] Figure 2 This is a schematic diagram of the three-dimensional fluid-structure interaction model established in this invention;

[0045] Figure 3 yes Figure 2 Front view diagram;

[0046] Figure 4 This is a flowchart of the partial secondary lining construction process in this invention. Detailed Implementation

[0047] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0049] This embodiment:

[0050] The present invention provides a method for determining the design parameters of a partial secondary lining for a TBM water diversion tunnel, see [link to relevant documentation]. Figure 1 As shown, it includes the following steps:

[0051] Step 1: Based on the engineering geological survey data and current specifications, determine the mechanical parameters, seepage parameters, tunnel cross-section design parameters, and fault fracture zone length L of the surrounding rock and fault fracture zone through which the tunnel passes, as shown in Table 1.

[0052] Let the lengths of the local secondary lining extending beyond the two ends of the fault fracture zone be L1 and L2, respectively (i.e., the length L of the fault fracture zone includes L1 and L2), and the thickness of the local secondary lining be d.

[0053] Specifically, the mechanical parameters, seepage parameters, tunnel cross-section design parameters, and specific parameters of the fault fracture zone length for the tunnel traversing the surrounding rock and fault fracture zone are shown in Tables 1 and 2.

[0054] Table 1 Specific parameters when the tunnel passes through Class II surrounding rock.

[0055]

[0056]

[0057] Table 2 Specific parameters for tunnels traversing Class I surrounding rock strata.

[0058]

[0059] Step 2: Based on the mechanical parameters, seepage parameters, tunnel cross-section design parameters, fault fracture zone length, and local secondary lining thickness of the surrounding rock and fault fracture zone traversed by the tunnel as shown in Table 1, a three-dimensional fluid-structure interaction calculation model is established using the finite difference method or finite element software (see [link to three-dimensional fluid-structure interaction calculation model]). Figure 2 and Figure 3 (As shown).

[0060] Step 3: Use a three-dimensional fluid-structure interaction calculation model to perform numerical simulation of the seepage field, surrounding rock deformation field and stress field around the tunnel during the tunnel crossing the fault fracture zone. Extract the pore water pressure, deformation, maximum principal stress distribution, minimum principal stress distribution and tunnel water inflow behind the initial plundered structure of the tunnel under the condition of no secondary lining.

[0061] Step 4: Determine the range of influence of the fault fracture zone on the tunnel based on the pore water pressure, deformation, maximum principal stress distribution, minimum principal stress distribution, and tunnel water inflow behind the initial support structure of the tunnel without secondary lining. Specifically, the influence range of the fault fracture zone on the tunnel, determined by the pore water pressure behind the initial support structure of the tunnel without secondary lining, is set as A1; the influence range of the fault fracture zone on the tunnel, determined by the deformation behind the initial support structure of the tunnel without secondary lining, is set as A2; the influence range of the fault fracture zone on the tunnel, determined by the maximum principal stress distribution behind the initial support structure of the tunnel without secondary lining, is set as A3; the influence range of the fault fracture zone on the tunnel, determined by the minimum principal stress distribution behind the initial support structure of the tunnel without secondary lining, is set as A4; and the influence range of the fault fracture zone on the tunnel, determined by the water inflow in the tunnel body without secondary lining, is set as A5. The union of A1, A2, A3, A4, and A5 is then calculated, and the union obtained is the influence range of the fault fracture zone on the tunnel.

[0062] Step 5: Based on the determined influence range of the fault fracture zone on the tunnel, obtain the initial value of the length L1 of the local secondary lining extending beyond one end of the fault fracture zone (i.e., the maximum value of L1 of the length L1 of the local secondary lining extending beyond one end of the fault fracture zone) and the initial value of the length L2 of the local secondary lining extending beyond the other end of the fault fracture zone (i.e., the maximum value of L2 of the length L2 of the local secondary lining extending beyond the other end of the fault fracture zone). Preferably, under the current working conditions, the maximum value of L1 is 6m, the maximum value of L2 is 4m, and the thickness d of the local secondary lining is taken as 30cm, 40cm, and 50cm according to the "Specifications for Design of Highway Tunnels, Volume 1, Civil Engineering" (JTG 3370.1-2018). More preferably, the thickness d of the local secondary lining is 30cm.

[0063] Step Six: Using a three-dimensional fluid-structure interaction calculation model, numerical simulations are performed on the seepage field characteristics, surrounding rock deformation, maximum principal stress, and minimum principal stress around the tunnel after the partial secondary lining is constructed. The maximum values ​​of pore water pressure, deformation, maximum principal stress, minimum principal stress, and tunnel inflow behind the tunnel lining structure after the partial secondary lining are obtained. These maximum values ​​are used as analysis indicators. Specifically, the maximum values ​​of L1 and L2 are reduced from their maximum values ​​to 0 at intervals of 1m each. This yields the maximum values ​​of pore water pressure, deformation, maximum principal stress, minimum principal stress, and tunnel water inflow behind the tunnel lining structure after partial secondary lining is applied, when L1 and L2 are set to different values ​​(i.e., when the maximum value of L1 is 6m, 5m, 4m, 3m, 2m, 1m, and the maximum value of L2 is 4m, 3m, 2m, 1m). Simultaneously, during the gradual reduction of the maximum values ​​of L1 (length of the partial secondary lining extending beyond one end of the fault fracture zone) and L2 (length of the partial secondary lining extending beyond the other end of the fault fracture zone), when a sudden change occurs in any of the analytical indicators, the length L of the partial secondary lining extending beyond the fault fracture zone at the time of the sudden change is obtained. i The value and the length L of the local secondary lining extending beyond the other end of the fault fracture zone. p If the value is L, then L will be L. i The previous set of values ​​L i-1 Value and L p The previous set of values ​​L p-1 The value is taken as the optimal length of the local secondary lining extending beyond both ends of the fault fracture zone under the current working condition (i.e., the optimal length of the local secondary lining extending beyond one end of the fault fracture zone under the current working condition is L). i-1 The optimal value for the length of the secondary lining extending beyond the other end of the fault fracture zone under the current working conditions is L. p-1 value).

[0064] By changing the thickness d of the local secondary lining, the optimal lengths of the secondary lining extending beyond one end of the fault fracture zone and the optimal lengths of the local secondary lining extending beyond the other end of the fault fracture zone are obtained when d is 40cm and 50cm.

[0065] Step 7: Based on the mechanical parameters, seepage parameters, tunnel cross-section design parameters, length of fault fracture zone and thickness of local secondary lining of the surrounding rock and fault fracture zone of the tunnel as shown in Table 2, establish a three-dimensional fluid-structure interaction calculation model using the finite difference method or finite element software.

[0066] Based on the three-dimensional fluid-structure interaction calculation model established in step seven, steps three to six were repeated to obtain the optimal length of the local secondary lining extending beyond both ends of the fault fracture zone under different working conditions (see Tables 3 and 4 for details).

[0067] Table 3. Optimal values ​​for the length of local secondary lining extending beyond both ends of the fault fracture zone when both sides of the fault are Class II surrounding rock.

[0068]

[0069]

[0070] Table 4. Optimal values ​​for the length of local secondary lining extending beyond both ends of the fault fracture zone when both sides of the fault are Class I surrounding rock.

[0071]

[0072] Step 9: Based on the optimal lengths of the local secondary linings extending beyond both ends of the fault fracture zone under different working conditions obtained in Step 8, regression analysis is performed. The resulting fortification lengths L1′ and L2′ of the local secondary linings extending beyond both ends of the fault fracture zone, as well as the thickness d of the local secondary linings, vary with the length L of the fault fracture zone and the grade of the surrounding rock on the left and right sides of the fault, as shown in Tables 5 to 8.

[0073] Table 5. Variation relationship when both sides of the fault are Class II surrounding rock.

[0074] Local secondary lining thickness d <![CDATA[Relationship between L1′ and L]]> <![CDATA[Correlation coefficient R 2 > d = 30cm <![CDATA[L1′=0.31L+1.16]]> 0.9959 d = 40cm <![CDATA[L1′=0.21L+2.01]]> 0.9800 d = 50cm <![CDATA[L1′=0.15L+2.35]]> 0.9783

[0075] Table 6 shows the variation relationship when both sides of the fault are Class II surrounding rock.

[0076] Local secondary lining thickness d <![CDATA[Relationship between L2' and L]]> <![CDATA[Correlation coefficient R 2 > d = 30cm <![CDATA[L2′=0.21L+1.26]]> 0.9494 d = 40cm <![CDATA[L2′=0.16L+1.66]]> 0.9143 d = 50cm <![CDATA[L2′=0.13L+1.88]]> 0.9657

[0077] Table 7. Variation Relationships When Both Sides of the Fault Are Class I Surrounding Rock

[0078] Local secondary lining thickness d <![CDATA[Relationship between L1' and L]]> <![CDATA[Correlation coefficient R 2 > d = 30cm <![CDATA[L1′=0.39L+0.19]]> 0.9924 d = 40cm <![CDATA[L1′=0.34L+0.15]]> 0.9880 d = 50cm <![CDATA[L1′=0.28L+0.48]]> 0.9923

[0079] Table 8. Relationship between changes when both sides of the fault are Class I surrounding rock.

[0080] Local secondary lining thickness d <![CDATA[Relationship between L2' and L]]> <![CDATA[Correlation coefficient R 2 > d = 30cm <![CDATA[L2′=0.26L+0.36]]> 0.9941 d = 40cm <![CDATA[L2′=0.24L+0.51]]> 0.9460 d = 50cm <![CDATA[L2′=0.18L+0.90]]> 0.9761

[0081] Preferably, the relationship between the fortification lengths L1′ and L2′ of the local secondary lining extending beyond both ends of the fault fracture zone and the thickness d of the local secondary lining, and the variation of the fault fracture zone length L and the surrounding rock grades on the left and right sides of the fault, is expressed as follows:

[0082]

[0083] Wherein, K1, K2, B1, and B2 represent model coefficients (specifically, the three-dimensional fluid-structure interaction calculation model), and their values ​​are related to the secondary lining thickness d and the surrounding rock grade on both sides of the fault. Preferably, when the surrounding rock grade on both sides of the fault is Class II and the local secondary lining thickness d is 30cm-50cm, the values ​​of K1 are 0.31-0.15, K2 are 0.21-0.13, B1 are 1.16-2.35, and B2 are 1.26-1.88; when the surrounding rock grade on both sides of the fault is Class I and the local secondary lining thickness d is 30cm-50cm, the values ​​of K1 are 0.28-0.39, K2 are 0.18-0.26, B1 are 0.15-0.48, and B2 are 0.36-0.90. Further preferred values ​​are as follows: when the surrounding rock grade on both sides of the fault is Class II and the local secondary lining thickness d is 30cm, 40cm, or 50cm, K1 is 0.31, 0.21, or 0.15; K2 is 0.21, 0.16, or 0.13; B1 is 1.16, 2.01, or 2.35; and B2 is 1.26, 1.66, or 1.88. When the surrounding rock grade on both sides of the fault is Class I and the local secondary lining thickness d is 30cm, 40cm, or 50cm, K1 is 0.39, 0.34, or 0.28; K2 is 0.26, 0.24, or 0.18; B1 is 0.19, 0.15, or 0.48; and B2 is 0.36, 0.51, or 0.90.

[0084] This invention also provides a method for constructing a partial secondary lining for a TBM water diversion tunnel after determining the design parameters (specifically including the construction range and thickness of the partial secondary lining) based on the aforementioned method for determining the design parameters of the partial secondary lining. The specific process is as follows:

[0085] Step 1: Preparations before construction:

[0086] Based on the surrounding rock data collected under the current working conditions, the design thickness d of the secondary lining under these conditions is determined according to the current "Specifications for Design of Highway Tunnels, Volume 1: Civil Engineering" (JTG 3370.1-2018). Based on the local secondary lining design thickness d, the design length of one end of the local secondary lining is calculated according to the length L of the fault fracture zone through which the tunnel passes.

[0087] "′

[0088] L1 and the fortification length L2 at the other end of the partial secondary lining, based on the fortification length L1 at one end of the partial secondary lining and the local

[0089] "′

[0090] Calculation of the design length L2 at the other end of the secondary lining; design length L of the local secondary lining. S (L S =L1+L2);

[0091] Professional surveyors used a total station to measure and lay out the cross-sections at both ends of the trolley based on the construction orientation measurement data such as the design drawings and the design liaison form, taking the turning point (control point) inside the tunnel as the backsight point, to ensure the tunnel clearance and the centerline of the lining;

[0092] The base plate is erected and leveled.

[0093] Step 2, Concrete Construction:

[0094] ① The concrete is mixed by the mixers arranged at the batching plant according to the mix proportion. The concrete mixed by the mixers is transported by locomotives to the pump trucks and delivered into the silo.

[0095] ② The concrete for the full circular lining is pumped into the formwork using a concrete pump. For the sidewalls, concrete is fed through pre-reserved windows in the side formwork, with chutes placed at the feeding openings on each sidewall, the height of the chutes from the bottom surface not exceeding 1.5m. Each sidewall is fed in batches not exceeding 50cm, with the concrete height difference between the two sidewalls not exceeding 50cm. After the sidewalls are poured, the arch concrete is poured using a jet pipe, and the arch is sealed promptly after pouring.

[0096] ③ The concrete for the full-circle lining is vibrated using an attached vibrator (the lining trolley has its own vibrator); in order to ensure that the concrete is fully vibrated, the technical staff of the work team must arrange the concrete pouring points and the number of workers in advance before the concrete construction to ensure that the concrete is vibrated and compacted.

[0097] Step 3, Reinforcing steel bar fabrication and installation:

[0098] Before the steel bars are fabricated, a steel bar material list is prepared according to the design drawings. Based on the steel bar material list, the existing steel bars are matched in length and the combination is optimized for cutting. The processed steel bars are transported to the tunnel by transport vehicles and locomotives. When the steel bars are lowered, they are neatly stacked according to specifications and models. The steel bar joints adopt an alternating welding and binding lap splicing method. When welding, the appropriate welding rods are used in strict accordance with the specifications and the weld standard requirements are met.

[0099] The steel reinforcement is installed using a steel reinforcement trolley. Before the steel reinforcement is tied, the surveyors mark out the station number, elevation and bottom slab structure boundary line according to the design cross-section data, thereby determining the outline template for steel reinforcement tying. The construction workers tie the steel reinforcement according to the design requirements based on the outline template.

[0100] Step 4: Template Installation

[0101] The lining is cast in one go using a hydraulic steel formwork trolley. After the steel reinforcement and embedded parts are installed and inspected, the steel formwork trolley is placed in place.

[0102] Step 5: Jointing of reinforced concrete lining:

[0103] Deformation joints should be installed at locations where the surrounding rock is classified and its shape changes, as well as at the intersection of wells and tunnels.

[0104] Step 6: Inventory Clearance and Acceptance

[0105] Clean up debris in the silo, rinse it thoroughly, drain any standing water, submit relevant acceptance documents for silo acceptance, and prepare for pouring by erecting simple scaffolding and safety railings, checking the vibrating equipment, and increasing lighting. The silo to be poured first undergoes internal three-stage inspection, and original documents are provided. The quality inspection department then requests the supervisor to conduct acceptance.

[0106] Step 7: Concrete pouring:

[0107] Concrete pouring can only proceed after the bedrock surface has passed inspection. For bedrock surface pouring, cement mortar should be poured before pouring the first batch of concrete to ensure unobstructed pumping and good bonding between the concrete and the bedrock surface.

[0108] Step 8, Demolding:

[0109] The formwork can only be removed after the concrete strength reaches the requirements of the construction drawings and specifications. After removal, the formwork should be cleaned to prepare it for the next stage of concrete pouring.

[0110] In this application, the model coefficients K1, B1; K2, B2 are obtained through a three-dimensional fluid-structure interaction numerical calculation model, which are mainly related to the surrounding rock grades on both sides of the fault in the model. For different surrounding rock conditions, corresponding relational expressions are obtained according to current specifications, thereby calculating the corresponding secondary lining design length, and the secondary lining is constructed based on this design length and the corresponding secondary lining design thickness.

[0111] Due to the current vigorous development of water conservancy projects, long water diversion tunnels like this will become increasingly common. Introducing local secondary lining design parameters allows for localized secondary lining construction at locations where it is actually needed, based on calculations, to achieve both seepage prevention and load-bearing capacity. Compared to the traditional method of constructing secondary lining along the entire length of the tunnel, this significantly reduces the construction period and saves materials, resulting in better economic benefits.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the design parameters of a partial secondary lining for a TBM water diversion tunnel, characterized in that, Includes the following steps: Step 1: Establish a three-dimensional fluid-structure interaction calculation model II based on the parameters of the tunnel traversing Class II surrounding rock and a three-dimensional fluid-structure interaction calculation model I based on the parameters of the tunnel traversing Class I surrounding rock. Step 2: Numerical simulations of the seepage field, surrounding rock deformation field, and stress field around the tunnel during the tunnel crossing the fault fracture zone are performed using the three-dimensional fluid-structure interaction calculation model II and the three-dimensional fluid-structure interaction calculation model I, respectively. This is to obtain the pore water pressure, deformation, maximum principal stress distribution, minimum principal stress distribution, and tunnel water inflow behind the initial support structure of the tunnel when the tunnel crosses Class II surrounding rock and when the tunnel crosses Class I surrounding rock without secondary lining. Step 3: Based on the pore water pressure, deformation, maximum principal stress distribution, minimum principal stress distribution, and tunnel inflow of the initial support structure of the tunnel under the conditions of Class II surrounding rock and Class I surrounding rock without secondary lining, determine the influence range of the fault fracture zone on the tunnel under the conditions of Class II surrounding rock and Class I surrounding rock, respectively. Step 4: Based on the determined influence range of the fault fracture zone on the tunnel, obtain the initial value of the length L1 of the local secondary lining extending beyond one end of the fault fracture zone and the initial value of the length L2 of the local secondary lining extending beyond the other end of the fault fracture zone. Step 5: Numerical simulations of the seepage field characteristics, surrounding rock deformation, maximum principal stress, and minimum principal stress around the tunnel after partial secondary lining are performed using three-dimensional fluid-structure interaction calculation model II and three-dimensional fluid-structure interaction calculation model I, respectively. This is to obtain the maximum values ​​of pore water pressure, deformation, maximum principal stress, minimum principal stress, and tunnel inflow behind the tunnel lining structure after partial secondary lining are performed when the tunnel passes through Class II surrounding rock and Class I surrounding rock, respectively. The maximum values ​​of pore water pressure, deformation, maximum principal stress, minimum principal stress, and tunnel inflow behind the tunnel lining structure after partial secondary lining are used as analysis indicators to determine the optimal values ​​of the local secondary lining design parameters under the current working conditions. Step 6: Perform regression analysis on the optimal values ​​of the local secondary lining design parameters under the current working conditions to obtain the design length of the local secondary lining extending beyond both ends of the fault fracture zone and the relationship between the thickness of the local secondary lining and the length of the fault fracture zone and the grade of the surrounding rock on the left and right sides of the fault.

2. The method for determining the design parameters of a partial secondary lining for a TBM water diversion tunnel according to claim 1, characterized in that, The parameters for the tunnel traversing Class II surrounding rock and Class I surrounding rock include the mechanical parameters, seepage parameters, design parameters of the tunnel cross-section, and the length L of the fault fracture zone of the surrounding rock and fault fracture zone.

3. The method for determining the design parameters of the secondary lining of a TBM water diversion tunnel according to claim 1, characterized in that, In step three, the specific method for determining the influence range of the fault fracture zone on the tunnel when the tunnel passes through Class II surrounding rock and when the tunnel passes through Class I surrounding rock is as follows: Let A1 be the range of influence of the fault fracture zone on the tunnel determined by the pore water pressure behind the initial support structure of the tunnel without secondary lining, A2 be the range of influence of the fault fracture zone on the tunnel determined by the deformation behind the initial support structure of the tunnel without secondary lining, A3 be the range of influence of the fault fracture zone on the tunnel determined by the maximum principal stress distribution behind the initial support structure of the tunnel without secondary lining, A4 be the range of influence of the fault fracture zone on the tunnel determined by the minimum principal stress distribution behind the initial support structure of the tunnel without secondary lining, and A5 be the range of influence of the fault fracture zone on the tunnel determined by the water inflow of the tunnel body without secondary lining. Calculate the union of A1, A2, A3, A4, and A5. The union obtained is the range of influence of the fault fracture zone on the tunnel.

4. The method for determining the design parameters of a partial secondary lining for a TBM water diversion tunnel according to claim 1, characterized in that, In step five, the specific method for determining the optimal value of the local secondary lining design parameters under the current working condition is as follows: The maximum values ​​of L1 and L2 are reduced from their maximum values ​​to 0 at intervals of 1m, so as to obtain the maximum pore water pressure, maximum deformation, maximum principal stress, maximum minimum principal stress and maximum water inflow of the tunnel body behind the tunnel lining structure after the local secondary lining is applied when the maximum values ​​of L1 and L2 are different. Meanwhile, as the maximum values ​​of the length L1 of the local secondary lining extending beyond one end of the fault fracture zone and the maximum value of the length L2 of the local secondary lining extending beyond the other end of the fault fracture zone are gradually reduced, when a sudden change occurs in one of the analytical indicators, the length L of the local secondary lining extending beyond the fault fracture zone at the time of the sudden change is obtained. i The value and the length L of the local secondary lining extending beyond the other end of the fault fracture zone. p If the value is L, then L will be L. i The previous set of values ​​L i-1 Value and L p The previous set of values ​​L p-1 The value is taken as the optimal length of the local secondary lining extending beyond both ends of the fault fracture zone under the current working conditions.

5. The method for determining the design parameters of a partial secondary lining for a TBM water diversion tunnel according to claim 1, characterized in that, In step six, the expressions for the relationship between the fortification lengths L1′ and L2′ of the local secondary lining extending beyond both ends of the fault fracture zone and the thickness d of the local secondary lining, and the changes in the length L of the fault fracture zone and the grade of the surrounding rock on the left and right sides of the fault, are as follows: K1, K2, B1, and B2 are model coefficients, whose values ​​are related to the length of the fault fracture zone and the surrounding rock grade on both sides of the fault.

6. The method for determining the design parameters of the secondary lining of a TBM water diversion tunnel according to claim 5, characterized in that, When the surrounding rock grade on both sides of the fault is Class II and the local secondary lining thickness d is 30cm-50cm, the value of K1 is 0.31-0.15, the value of K2 is 0.21-0.13, the value of B1 is 1.16-2.35, and the value of B2 is 1.26-1.

88. When the surrounding rock grade on both sides of the fault is Class I and the local secondary lining thickness d is 30cm-50cm, the values ​​of K1 are 0.28-0.39, K2 are 0.18-0.26, B1 are 0.15-0.48, and B2 are 0.36-0.

90.

7. The method for determining the design parameters of a partial secondary lining for a TBM water diversion tunnel according to claim 6, characterized in that, When the surrounding rock grade on both sides of the fault is Class II and the local secondary lining thickness d is 30cm, 40cm or 50cm, the values ​​of K1 are 0.31, 0.21 or 0.15, K2 is 0.21, 0.16 or 0.13, B1 is 1.16, 2.01 or 2.35, and B2 is 1.26, 1.66 or 1.

88. When the surrounding rock grade on both sides of the fault is Class I and the local secondary lining thickness d is 30cm, 40cm or 50cm, the values ​​of K1 are 0.39, 0.34 or 0.28, K2 is 0.26, 0.24 or 0.18, B1 is 0.19, 0.15 or 0.48, and B2 is 0.36, 0.51 or 0.

90.

8. A construction method for partial secondary lining of a TBM water diversion tunnel, characterized in that, Includes the following steps: Step 1: Preparations before construction: The design parameters of the local secondary lining of the TBM water diversion tunnel are determined using the design parameter determination method for local secondary lining as described in any one of claims 1-7. Based on the determined design thickness d of the secondary lining under the surrounding rock conditions, and based on the design thickness d of the local secondary lining, the design length L1′ of one end of the local secondary lining and the design length L2′ of the other end of the local secondary lining are calculated according to the length L of the fault fracture zone through which the tunnel passes. Based on the design length L1′ of one end of the local secondary lining and the design length L2′ of the other end of the local secondary lining, the design length L of the local secondary lining is calculated. S , where L S =L1′+L2′; Construction orientation measurements were taken for the location of the local secondary lining, and the formwork for the bottom slab was erected. Step 2, Concrete construction; Step 3: Fabrication and installation of reinforcing bars; Step 4: Template installation; Step 5: Jointing of reinforced concrete lining; Step 6: Inventory clearance and acceptance; Step 7: Concrete pouring; Step 8: Demolding.

9. The construction method for partial secondary lining of a TBM water diversion tunnel according to claim 8, characterized in that, The local secondary lining protection parameters include the construction range and thickness of the local secondary lining.

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