High pressure water tunnel lining structure containing prefabricated wide slit structure and construction method

Abstract

The application discloses a high-pressure water tunnel lining structure with prefabricated wide slot structure in the technical field of hydraulic engineering, which comprises a spray layer and a lining arranged on the inner wall of the tunnel in sequence, and a plurality of anchor rods penetrating through the lining and the spray layer and extending into surrounding rock, a plurality of prefabricated wide slots are arranged on the lining in a circumferential direction, the length direction of the prefabricated wide slot is consistent with the extension direction of the tunnel, the depth of the prefabricated wide slot is the same as the thickness of the lining, and the prefabricated wide slot is filled with an elastic water stop structure. The lining structure utilizes the anchor rods to closely connect the lining and the surrounding rock, plays a similar group pile effect, and transmits part of the internal water pressure of the reinforced concrete lining to the surrounding rock through the anchor rods, so that the radial and circumferential deformation amounts of the lining are effectively reduced; when the prefabricated wide slot is enlarged due to the radial and circumferential deformation of the lining, the water stop effect of the prefabricated wide slot structure is not lost, the internal water cannot exude through the prefabricated wide slot structure, and the long-term stable operation of the tunnel is ensured.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering technology, and in particular to a lining structure and construction method for a high-pressure hydraulic tunnel with a prefabricated wide-joint structure. Background Technology

[0002] Pressurized hydraulic tunnels are important water conveyance structures, often employing circular cross-section lining structures. Their structural stress characteristics involve radial deformation of the lining towards the surrounding rock under internal water pressure, generating circumferential tensile force. Depending on the lining design principles and working conditions, the internal water pressure is partially or completely transferred to the surrounding rock through the lining. With the construction and development of large-scale water diversion projects and pumped storage power stations, there is a need to construct high-pressure (H-value) and large-diameter (D-value) hydraulic tunnels. Current hydraulic tunnel designs mainly fall into the following categories:

[0003] Design theory for unlined tunnels: If the surrounding rock has high strength and modulus, good integrity, and the minimum ground stress level is higher than the internal water pressure, pressurized tunnels can be designed according to the unlined tunnel design theory. That is, after excavation, only shotcrete and anchor support is carried out on the surrounding rock, without lining. Its disadvantages are: high requirements for geological conditions such as surrounding rock grade and ground stress, which are difficult to meet for most pressurized water tunnel projects; over-excavation and under-excavation, undulations, and rough surfaces of shotcrete result in a large roughness around the tunnel, increasing head loss along the tunnel and reducing water conveyance and power generation efficiency; long-term immersion of the surrounding rock underwater may gradually deteriorate, leading to long-term stability problems of the tunnel.

[0004] The design theory of crack-limited lining structures: The current hydraulic tunnel design code recommends this method, which has a clear theory and relatively mature technology. The main technical solution is as follows: A reinforced concrete structure is used for the lining. Internal water pressure acts on the inner surface of the lining, radially compressing the lining and generating circumferential tensile stress in the lining structure. When the internal water pressure is low, the tensile stress value inside the lining is lower than the tensile strength of the concrete, the lining structure remains intact, and most of the internal water pressure load is borne by the lining concrete and reinforcement, with minimal transfer to the surrounding rock. As the internal water pressure increases, the tensile stress value inside the lining continuously increases. After exceeding the tensile strength of the concrete, the concrete cracks, forming fissures. However, the crack opening and spacing can be controlled by the reinforcement. Its disadvantage is that under high water head, the concrete lining of pressurized hydraulic tunnels may crack and leak. Under the action of high external seepage flow, the lining of the pressure tunnel may separate from the surrounding rock, leading to significant changes in the operating mechanism and hydraulic conduction behavior of the pressure tunnel, posing a potential safety hazard to the tunnel. Meanwhile, high-pressure internal and external water may cause the groundwater level in the mountain to rise, threatening the safety of the slope. Therefore, the bearing capacity of the crack-limiting lining is limited and it is not suitable for tunnels with high HD values.

[0005] The design theory of permeable lining structure: The lining adopts permeable concrete or pre-drainage holes and other permeable measures. After the tunnel is filled with water, it can achieve internal and external pressure balance, so as to withstand high HD value internal water pressure. Its disadvantages are: high pressure internal water splits the surrounding rock, causing internal water to seep out, which may cause mountain stability problems; excessive internal and external water cause water balance problems; internal water seepage causes the external water pressure of the upper pressurized tunnel to increase, and the external water pressure may diffuse to the surrounding rock of the lower pressure pipeline section, resulting in increased drainage volume of the lower pressure pipeline and prominent problems of external pressure instability of steel pipe and steel lining.

[0006] Steel-lined design theory: First, excavate a tunnel with a diameter 1.2m larger than the cross-section of the water passage. Continuous welding of steel pipes is then carried out within the tunnel to form an internally sealed steel plate lining. Concrete is then backfilled and grouted between the outer side of the steel lining and the tunnel wall. This technical solution is mainly used for pressure pipelines near the powerhouse in high-head conventional hydropower stations or pumped-storage power stations. Its disadvantages are: it requires excavating a tunnel with a diameter larger than the cross-section of the water passage, which may deteriorate the stability of the surrounding rock; the excavation and subsequent backfilling of concrete require a large volume; although the steel lining has strong internal pressure bearing capacity, it is prone to instability under external pressure, and external pressure control often requires additional drainage tunnels, resulting in high costs. Summary of the Invention

[0007] To address the problem that existing concrete lining structures for pressurized hydraulic tunnels are not adaptable to high HD values, the technical problem to be solved by this invention is to provide a lining structure for high-pressure hydraulic tunnels with prefabricated wide joints that can withstand high HD values ​​and a construction method thereof.

[0008] The technical solution adopted by this invention to solve its technical problem is:

[0009] A high-pressure hydraulic tunnel lining structure with prefabricated wide joints includes a sprayed layer and a lining sequentially arranged on the inner wall of the tunnel, and multiple anchor bolts that pass through the lining and the sprayed layer and extend into the surrounding rock. Multiple prefabricated wide joints are arranged at intervals along the circumference of the lining. The length direction of the prefabricated wide joints is consistent with the extension direction of the tunnel, and the depth of the prefabricated wide joints is the same as the thickness of the lining. The prefabricated wide joints are filled with an elastic water-stopping structure.

[0010] Furthermore, the thickness of the sprayed layer is not less than 10cm, and the concrete grade is not lower than C30.

[0011] Furthermore, the lining is a reinforced concrete lining, with a single section length of 9-12m and a thickness of not less than 35cm, and the central angle corresponding to a single lining section separated by prefabricated wide joints does not exceed 90°.

[0012] Furthermore, multiple rows of anchor bolt groups are installed along the tunnel extension direction. Each row of anchor bolt groups includes multiple anchor bolts arranged radially along the circumference of the tunnel. The anchor bolts penetrate at least 1m into the unloosened rock mass, with the exposed end length on the tunnel wall being 0.3 to 0.5m. The anchor bolts are arranged in the circumferential near-mid-span part of a single lining block.

[0013] Furthermore, the number of prefabricated wide joints is 4-8, the width of the wide joints is 2-3cm, and they are evenly spaced along the circumference of the lining.

[0014] Furthermore, the elastic water-stopping structure is an elastic sealant with a modulus of less than 20 MPa, and the bond strength between the sealant and the concrete is not less than the highest internal water pressure in the tunnel.

[0015] The construction method for the lining structure of a high-pressure hydraulic tunnel containing a precast wide-joint structure includes the following steps:

[0016] Step 1: Determine the cross-sectional dimensions of the tunnel according to project requirements and calculate the maximum internal water pressure inside the tunnel;

[0017] Step 2: Based on the cross-sectional dimensions of the tunnel, preliminarily determine the lining thickness, the number of prefabricated wide joints, and the spacing of the anchor bolts;

[0018] Step 3: Calculate the radial deformation of the above-mentioned preliminary lining structure based on the internal water pressure to obtain the opening degree of each prefabricated wide joint;

[0019] Step 4: Determine if the opening is within a reasonable range. If not, reset the lining structure in Step 2 until the opening of the precast wide joint meets the requirements.

[0020] Step 5: After meeting the requirements of Step 4, proceed with the construction of the lining structure according to Step 2. The construction process shall be carried out in the following order: excavating the tunnel, spraying the spray layer, laying anchor bolts, pouring the lining, setting the precast wide joint, and filling the precast wide joint with an elastic water-stop structure.

[0021] Furthermore, with the radius of the water-passing section on the inner side of the lining as r0, the radius of the outer side of the lining / inner side of the shotcrete layer as r1, the radius of the outer side of the shotcrete layer / inner side of the surrounding rock as r2, the radius of the loosened zone as r3, the distance from the rock mass depth of the anchor bolt to the center line of the tunnel as r4, and the anchor bolt spacing of a single lining block along the tunnel axis as s, where s is less than 1.0m; when the central angle α corresponding to a single lining block is 90° or the diameter of the water-passing section of the tunnel is greater than 6m, n are symmetrically arranged along the circumferential direction relative to the mid-span of the single lining block. a = 2 anchor bolts, spaced at 30°; when the central angle corresponding to a single lining block is less than or equal to α = 60° and the tunnel water-passing cross-section diameter r0 is less than 6m, n anchor bolts are set at the mid-span of the single lining block along the circumferential direction. a = 1 anchor bolt.

[0022] Furthermore, when calculating the opening of precast wide joints, the following methods can be used for approximate calculation, followed by numerical simulation analysis:

[0023] The internal water pressure P0 acts on the radial pressure F of a unit anchor bolt, satisfying:

[0024] F = Ak a p0

[0025] Where, k a The load-sharing factor for a single anchor bolt is determined by the anchor bolt / rock stiffness ratio. A represents the cross-sectional area of ​​the anchor bolt body, and the diameter d of the anchor bolt borehole is generally taken as 10 cm. E a The modulus of the anchor bolt material is taken as the weighted average of the modulus of the reinforcing steel inside the anchor bolt and the modulus of the backfill grouting material. When no measured data is available, a value of 30–50 GPa is used. r Determine the deformation modulus of the loosened rock mass;

[0026] The additional radial stress directly transmitted from the lining to the surrounding rock can be calculated using the radial stress diffusion formula for circular tunnels.

[0027]

[0028] Zi is the calculation depth. When i=1, it corresponds to the sprayed layer, and z1=(r2-r1) / 2 is taken. When i=2, it corresponds to the loosened rock mass, and z2=(r3-r2) / 2 is taken. When i=3, it corresponds to the unloosened rock layer within the anchoring depth, and z3=(r4-r3) / 2 is taken. When i=4, it corresponds to the unloosened rock layer outside the anchoring depth, and z4=r4+1.5l' is taken. l' is the depth of the anchor rod into the rock.

[0029] The radial deformation of the lining under internal water pressure is:

[0030]

[0031] Where: when i is 1, 2, 3, 4, Δz i The thicknesses of the sprayed layer, loosened zone, unloosened rock strata within the anchoring depth, and rock mass within the anchoring depth are calculated respectively. The calculated rock mass thickness within the anchoring depth is taken as three times the anchor rod insertion depth l'.

[0032] Then the average circumferential strain of the lining at this time is:

[0033]

[0034] Since the lining is a reinforced concrete structure, its stiffness is much greater than that of the wide joints. Therefore, almost all of the circumferential deformation of the lining is borne by the precast wide joints, which is converted into the opening of the wide joints. Integrating the lining strain along the circumferential direction of a single lining piece yields the opening of each wide joint:

[0035]

[0036] Considering that existing joint filler materials are generally in the elastic stage when the strain rate is less than 0.2, the width of the joint can be obtained.

[0037] Furthermore, when setting up precast wide joints, the wide joint formwork is first precast and placed at the end of the longitudinal formwork of the segmented lining. Then, a steel cage is arranged inside the formwork, and concrete is poured. After the concrete has initially set, the wide joint formwork is removed, and grouting material is injected into the joint to form an elastic water-stopping structure.

[0038] Furthermore, when setting up precast wide joints, the precast segmented lining steel cages are first fixed to the tunnel wall by anchor rods extending from the spray layer, leaving a gap between adjacent steel cages. Then, the trolley template is installed according to the control points, and the entire ring is poured in one go. After the concrete has initially set, a concrete cutter is used to cut through the lining at the reserved gap of the segmented steel cages. Finally, the joint is filled with sealant to form an elastic water-stop structure.

[0039] The beneficial effects of this invention are as follows: When the reinforced concrete lining is filled with water and the inner surface of the lining is subjected to high internal water pressure, the anchor structure tightly connects the lining with the surrounding rock, playing a role similar to a pile group. The reinforced concrete lining transmits part of the internal water pressure to the surrounding rock through the anchor, thereby effectively reducing the radial deformation of the lining, which in turn reduces the circumferential deformation of the lining. At the same time, when the precast wide joint increases due to radial and circumferential deformation during the filling and drainage operation of the pressurized tunnel, the precast wide joint structure will not lose its water-stopping effect, ensuring that the internal water will not seep out through the precast wide joint structure, thus ensuring the long-term stable operation of the tunnel. Attached Figure Description

[0040] Figure 1 This is a cross-sectional view of the lining structure of the present invention;

[0041] Figure 2 This is a schematic diagram of the structure of the present invention, which uses a wide-slit template to set a prefabricated wide slit.

[0042] Figure 3 This is a schematic diagram of the structure of the present invention, which sets prefabricated wide joints by cutting the lining;

[0043] The markings in the diagram are: 1-surrounding rock, 2-sprayed layer, 3-lining, 4-anchor bolt, 5-precast wide joint, 6-reinforcing cage, 7-joint filler material, 8-gap. Detailed Implementation

[0044] The invention will be further described below with reference to the accompanying drawings.

[0045] It should be noted that if this invention uses directional terms such as up, down, left, right, front, and back, these are for describing the relative positions of components and are not specific references to the absolute positions of related components or the relationships between them. They are only used to explain the relative positional relationships and movements of components in a specific posture. If the specific posture changes, the directional indication will also change accordingly. If this invention uses terms related to quantity such as "many," "multiple," or "several," these specifically refer to two or more.

[0046] like Figure 1 As shown, the prefabricated wide-joint high-pressure hydraulic tunnel lining structure of the present invention includes a sprayed layer 2 and a lining 3 sequentially arranged on the inner wall of the tunnel, and multiple anchor bolts 4 passing through the lining 3 and the sprayed layer 2 and extending into the surrounding rock 1. Multiple prefabricated wide joints 5 are arranged at intervals along the circumference of the lining 3. The length direction of the prefabricated wide joints 5 is consistent with the extension direction of the tunnel. The depth of the prefabricated wide joints 5 is the same as the thickness of the lining 3. The prefabricated wide joints 5 are filled with an elastic water-stopping structure. Compared to traditional tunnel structures, this invention utilizes anchor bolts 4 to tightly connect the lining 3 to the surrounding rock 1, achieving an effect similar to pile groups. This allows the reinforced concrete lining 3 to transfer some of the internal water pressure to the surrounding rock 1 through the anchor bolts 4, effectively reducing the radial deformation of the lining 3, which in turn reduces the circumferential deformation. Simultaneously, through precise calculations, even when the precast wide joint 5 enlarges due to radial and circumferential deformation during the filling and drainage operation of the pressurized tunnel, the precast wide joint 5 will not lose its water-stopping effect, ensuring that internal water will not seep out through the precast wide joint 5, thus ensuring the long-term stable operation of the tunnel.

[0047] To further improve the stability and structural strength of the entire lining structure, the present invention provides the following preferred solutions:

[0048] The thickness of the sprayed layer 2 should be no less than 10cm, and the concrete grade should be no less than C30.

[0049] The lining 3 is a reinforced concrete lining with a single section length of 9-12m, which is consistent with the length of the trolley to facilitate pouring construction. Considering structural strength, the thickness should not be less than 35cm. In order to prevent cracks from appearing in the middle of the lining 3 during deformation, the central angle of the single lining 3 separated by the precast wide joint 5 should not exceed 90°.

[0050] Regarding the arrangement of anchor bolts 4, the preferred option is to set up multiple rows of anchor bolt groups along the tunnel extension direction. Each row of anchor bolt groups includes multiple anchor bolts 4 arranged radially along the circumference of the tunnel. The anchor bolts 4 penetrate at least 1m into the unloosened rock mass, and the exposed end length on the tunnel wall is 0.3 to 0.5m, ensuring full connection between the shotcrete layer 2 and the lining 3 and the anchor bolts 4. The anchor bolts can be arranged in the circumferential near-mid-span part of a single lining block.

[0051] The number of prefabricated wide joints 5 is 4-8, with a width of 2-3 cm, and they are evenly spaced along the circumference of the lining 3. The number of prefabricated wide joints 5 is mainly selected according to the tunnel diameter. For example, for a tunnel with an excavation diameter of 4m to 5m, it is advisable to divide the lining 3 into four circumferential sections, i.e., the number of prefabricated wide joints 5 is 4; if the excavation diameter is 6m to 10m, it is divided into six circumferential sections, and the number of wide joints 5 is also 6. The width of the wide joint is 2-3cm, which is mainly determined based on the strain rate of general joint filler materials. It is generally believed that the joint filler material is in the elastic stage when the strain rate is less than 0.2. If the prefabricated wide joints 5 are too wide, the joint filler material will be prone to cracking. 2-3cm is more appropriate.

[0052] When selecting the filling material for the elastic waterstop structure, the elastic waterstop structure preferably uses an elastic sealant with a modulus of less than 20 MPa, and the bond strength between the sealant and the concrete is not less than the highest internal water pressure in the tunnel.

[0053] The construction method for the above-mentioned precast wide-joint high-pressure hydraulic tunnel lining structure includes the following steps:

[0054] Step 1: Determine the cross-sectional dimensions of the tunnel according to project requirements and calculate the maximum internal water pressure inside the tunnel;

[0055] Step 2: Based on the cross-sectional dimensions of the tunnel, preliminarily determine the thickness of the lining 3, the number of prefabricated wide joints 5, and the spacing of the anchor bolts 4;

[0056] Step 3: Calculate the radial deformation of the above-mentioned preliminary lining structure based on the internal water pressure to obtain the opening of each prefabricated wide joint 5.

[0057] Step 4: Determine if the opening is within a reasonable range. If not, reset the lining structure in Step 2 until the opening of the precast wide joint 5 meets the requirements.

[0058] Step 5: After meeting the requirements of Step 4, proceed with the construction of the lining structure according to Step 2. The construction process shall be carried out in the following order: excavating the tunnel, spraying the spray layer, laying anchor bolts, pouring the lining, setting the precast wide joint, and filling the precast wide joint with an elastic water-stop structure.

[0059] The number of anchor bolts can be determined as follows: The radius of the water-passing section inside the lining is r0, the radius of the outer side of the lining / inner side of the shotcrete layer is r1, the radius of the outer side of the shotcrete layer / inner side of the surrounding rock is r2, the radius of the loosened zone is r3, the distance from the anchor bolt insertion depth into the rock mass to the centerline of the tunnel is r4, and the anchor bolt spacing along the tunnel axis for a single lining block is s, where s is less than 1.0m; when the central angle α corresponding to a single lining block is 90° or the diameter of the water-passing section of the tunnel is greater than 6m, n anchor bolts are symmetrically arranged along the circumferential direction relative to the mid-span of the single lining block. a= 2 anchor bolts, spaced at 30°; when the central angle corresponding to a single lining block is less than or equal to α = 60° and the tunnel water-passing cross-section diameter r0 is less than 6m, n anchor bolts are set at the mid-span of the single lining block along the circumferential direction. a = 1 anchor bolt.

[0060] When calculating the opening of precast wide joints, the following approximate calculation methods can be used, followed by numerical simulation analysis:

[0061] The internal water pressure P0 acts on the radial pressure F of a unit anchor bolt, satisfying:

[0062] F = Ak a p0

[0063] Where, k a The load-sharing factor for a single anchor bolt is determined by the anchor bolt / rock stiffness ratio. A represents the cross-sectional area of ​​the anchor bolt body, and the diameter d of the anchor bolt borehole is generally taken as 10 cm. E a The modulus of the anchor bolt material is taken as the weighted average of the modulus of the reinforcing steel inside the anchor bolt and the modulus of the backfill grouting material. When no measured data is available, a value of 30–50 GPa is used. r Determine the deformation modulus of the loosened rock mass;

[0064] The additional radial stress directly transmitted from the lining to the surrounding rock can be calculated using the radial stress diffusion formula for circular tunnels.

[0065]

[0066] Zi is the calculation depth. When i=1, it corresponds to the sprayed layer, and z1=(r2-r1) / 2 is taken. When i=2, it corresponds to the loosened rock mass, and z2=(r3-r2) / 2 is taken. When i=3, it corresponds to the unloosened rock layer within the anchoring depth, and z3=(r4-r3) / 2 is taken. When i=4, it corresponds to the unloosened rock layer outside the anchoring depth, and z4=r4+1.5l' is taken. l' is the depth of the anchor rod into the rock.

[0067] The radial deformation of the lining under internal water pressure is:

[0068]

[0069] Where: when i is 1, 2, 3, 4, Δz i The thicknesses of the sprayed layer, loosened zone, unloosened rock strata within the anchoring depth, and rock mass within the anchoring depth are calculated respectively. The calculated rock mass thickness within the anchoring depth is taken as three times the anchor rod insertion depth l'.

[0070] Then the average circumferential strain of the lining at this time is:

[0071]

[0072] Since the lining is a reinforced concrete structure, its stiffness is much greater than that of the wide joints. Therefore, almost all of the circumferential deformation of the lining is borne by the precast wide joints, which is converted into the opening of the wide joints. Integrating the lining strain along the circumferential direction of a single lining piece yields the opening of each wide joint:

[0073]

[0074] Considering that existing joint filler materials are generally in the elastic stage when the strain rate is less than 0.2, the width of the joint can be obtained.

[0075] When setting the prefabricated wide joint 5, the present invention provides two solutions:

[0076] Option 1, such as Figure 2 As shown, the wide joint formwork is first prefabricated and placed at the end of the longitudinal formwork of the segmented lining. Then, the steel cage 6 is arranged inside the formwork, and concrete is poured. After the concrete has initially set, the wide joint formwork is removed, and the joint filler material 7 is injected into the joint to form an elastic water-stop structure.

[0077] Option 2, such as Figure 3 As shown, the prefabricated segmented lining steel cage 6 is first fixed to the tunnel wall by the anchor rod 4 extending from the spray layer 2. A gap 8 is left between two adjacent steel cages 6. Then, the trolley template is installed according to the control points and the whole ring is poured in one go. After the concrete has initially set, a concrete cutter is used to cut through the lining 3 at the reserved gap 8 of the segmented steel cage 6. Finally, the joint filling material 7 is injected into the joint to form an elastic water-stop structure.

[0078] Both schemes can construct precast wide joints 5 on the lining 3 without damaging the steel cage 6 in the lining structure, thus ensuring the stability and structural strength of the entire lining structure.

Claims

1. A lining structure for high-pressure hydraulic tunnels containing precast wide-joint structures, characterized by: The system includes a sprayed layer (2) and a lining (3) sequentially installed on the inner wall of the tunnel, and multiple anchor bolts (4) that pass through the lining (3) and the sprayed layer (2) and extend into the surrounding rock (1). The lining (3) has multiple prefabricated wide joints (5) spaced along its circumference. The length direction of the prefabricated wide joints (5) is consistent with the extension direction of the tunnel, and the depth of the prefabricated wide joints (5) is the same as the thickness of the lining (3). The prefabricated wide joints (5) are filled with an elastic water-stopping structure. The lining (3) is a reinforced concrete lining with a single section length of 9-12m and a thickness of not less than 35cm. The single lining (3) is separated by the prefabricated wide joints (5). The corresponding central angle does not exceed 90°. Multiple rows of anchor bolt groups are set along the tunnel extension direction. Each row of anchor bolt groups includes multiple anchor bolts (4) arranged radially along the circumference of the tunnel. The anchor bolts (4) penetrate at least 1m into the unloosened rock mass, and the exposed end length on the tunnel wall is 0.3~0.5m. The anchor bolts are arranged in the circumferential near-mid span of a single lining block. The number of prefabricated wide joints (5) is 4-8, the width of the wide joint is 2-3cm, and they are evenly spaced along the circumference of the lining (3). The elastic water-stopping structure is an elastic sealant with a modulus of less than 20MPa. The bonding strength between the sealant and the concrete is not lower than the highest internal water pressure in the tunnel.

2. The high-pressure hydraulic tunnel lining structure with prefabricated wide-joint structure as described in claim 1, characterized in that: The thickness of the sprayed layer (2) shall not be less than 10cm, and the concrete grade shall not be lower than C30.

3. The construction method for the lining structure of a high-pressure hydraulic tunnel containing a prefabricated wide-joint structure as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1: Determine the cross-sectional dimensions of the tunnel according to project requirements and calculate the maximum internal water pressure inside the tunnel; Step 2: Based on the cross-sectional dimensions of the tunnel, preliminarily determine the thickness of the lining (3), the number of prefabricated wide joints (5), and the spacing of the anchor bolts (4); Step 3: Calculate the radial deformation of the above-mentioned initial lining structure based on the internal water pressure to obtain the opening degree of each prefabricated wide joint (5); Step 4: Determine whether the opening is within a reasonable range. If not, reset the lining structure of Step 2 until the opening of the precast wide joint (5) meets the requirements. Step 5: After meeting the requirements of Step 4, proceed with the construction of the lining structure according to Step 2. The construction process shall be carried out in the following order: excavating the tunnel, spraying the spray layer, laying anchor bolts, pouring the lining, setting the precast wide joint, and filling the precast wide joint with an elastic water-stop structure.

4. The construction method of the high-pressure hydraulic tunnel lining structure with prefabricated wide-joint structure as described in claim 3, characterized in that: Let the radius of the water-passing section on the inner side of the lining be r0, and the radius of the outer side of the lining / inner side of the sprayed layer be r0. The radius of the outer side of the spray layer / inner side of the surrounding rock is The radius of the loosening zone is The depth of the anchor bolt insertion into the rock mass corresponds to the distance from the centerline of the tunnel. The anchor spacing of a single lining block along the tunnel axis is s, and s is less than 1.0m; when the central angle α corresponding to a single lining block is 90° or the diameter r0 of the tunnel water passage section is greater than 6m, n are symmetrically arranged along the circumferential direction relative to the mid-span of the single lining block. a = 2 anchor bolts, spaced at 30°; when the central angle corresponding to a single lining block is less than or equal to α=60° and the tunnel water-passing cross-section diameter r0 is less than 6m, n anchor bolts are set at the mid-span of the single lining block along the circumferential direction. a =1 anchor bolt.

5. The construction method for the lining structure of a high-pressure hydraulic tunnel containing a prefabricated wide-joint structure as described in claim 4, characterized in that, When calculating the opening degree of precast wide joints, the following approximate calculation methods can be used, followed by numerical simulation analysis: The radial pressure P0 exerted by the internal water pressure on a unit anchor bolt satisfy: ； Where, k a The load-sharing factor for a single anchor bolt is determined by the anchor bolt / rock stiffness ratio. A represents the cross-sectional area of ​​the anchor bolt body; the diameter d of the anchor bolt borehole is generally taken as 10cm; E a The modulus of the anchor bolt material is taken as the weighted average of the modulus of the reinforcing steel inside the anchor bolt and the modulus of the backfill grouting material. When no measured data is available, a value of 30-50 GPa is used. r Deformation modulus of loosened rock mass; The additional radial stress directly transmitted from the lining to the surrounding rock can be calculated using the radial stress diffusion formula for a circular tunnel. ； Zi represents the calculation depth, and i=1 corresponds to the spray layer. When i=2, it corresponds to the loosened sphere rock mass. When i=3, it corresponds to an unloose rock layer within the anchoring depth. i=4 corresponds to unloosened rock strata beyond the anchoring depth, and is taken as... , This refers to the depth of the anchor bolt into the rock. The radial deformation of the lining under internal water pressure is: ； Where: when i is 1, 2, 3, 4 The thickness of the sprayed layer, the thickness of the loosened zone, the thickness of the unloosened rock layer within the anchoring depth, and the thickness of the rock mass within the anchoring depth are calculated respectively. The thickness of the rock mass within the anchoring depth is taken as the depth of the anchor rod into the rock. 3 times, Then the average circumferential strain of the lining at this time is: ； Since the lining is a reinforced concrete structure, its stiffness is much greater than that of the wide joints. Therefore, almost all of the circumferential deformation of the lining is borne by the precast wide joints, which is converted into the opening of the wide joints. Integrating the lining strain along the circumferential direction of a single lining piece yields the opening of each wide joint: ； Considering that existing joint filler materials are generally in the elastic stage when the strain rate is less than 0.2, the width of the joint can be obtained.

6. The construction method of the high-pressure hydraulic tunnel lining structure with prefabricated wide-joint structure as described in claim 3, characterized in that: When setting up a precast wide joint (5), first precast the wide joint body template and place it at the end of the longitudinal template of the block lining. Then, arrange the steel cage (6) in the template, pour concrete, and remove the wide joint body template after the concrete has initially set. Inject the joint filling material (7) into the joint body to form an elastic water-stop structure. Alternatively, when setting up a precast wide joint (5), the precast segmented lining steel cage (6) is first fixed to the tunnel wall by the anchor rod (4) extending out of the spray layer (2), and a gap (8) is left between two adjacent steel cages (6). Then, the trolley template is installed according to the control point and the whole ring is poured in one go. After the concrete has initially set, a concrete cutter is used to cut through the lining (3) at the reserved gap (8) of the segmented steel cage (6). Finally, the joint filling material (7) is injected into the joint to form an elastic water-stop structure.

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