Safety prevention and control method for geological risks in large-span pumped storage power station tunnel construction

Abstract

The present application relates to pumped storage power station technical field, relates to the large span pumped storage power station tunnel construction geological risk safety prevention method.The present application is in view of the large span pumped storage power station tunnel along the strike construction in the inclined stratum, it is divided into three parts along the tendency, first, the half side of the tendency is relatively high and is cut, then the tendency low area is excavated and is supported in time, during this period, the inclined stratum outside the cut area is allowed to creep displacement to the cut area, and the creep of the stratum mostly occurs in the initial period after being exposed, and the inclined stratum of the high area of the tendency can reduce the creep after a large amount of creep after construction. Then according to the creep characteristic curve of the tendency stratum, the residual creep deformation is obtained, so that the high area of the tendency is accurately expanded, and the final creep deformation of the inclined stratum is ensured. The tunnel section still meets the requirements. The present application is especially suitable for the tunnel construction condition that the tunnel section is large and the inclined stratum is affected by the eccentric compression, and the present application is simple in construction and easy to popularize.

Description

Technical Field

[0001] The present invention relates to the technical field of pumped-storage power stations, and in particular to a method for safely preventing and controlling geological risks in tunnel construction of large-span pumped-storage power stations. Background Art

[0002] A pumped-storage power station uses electricity generated during low-load periods to pump water to an upper reservoir, releasing it to a lower reservoir for power generation during peak load periods. Its structure primarily consists of an upper reservoir, a lower reservoir, and a tunnel connecting the two. Tunnels for pumped-storage power stations are typically constructed within rock formations, which often have an inclined orientation due to geological activity. Tunnel construction within inclined rock formations is susceptible to lateral pressure. After tunnel excavation, rock formations inclined to the higher side tend to creep into the excavated tunnel. This can cause changes in the tunnel's cross-sectional dimensions, impacting the accuracy of subsequent power regulation during pumped-storage operations. It can also damage tunnel support, compromising the tunnel's long-term safety. Tunnel dimensions for pumped-storage power stations vary depending on their intended purpose. Construction of large-cross-section tunnels is particularly challenging, especially when the inclined rock formations are subject to lateral pressure. Summary of the Invention

[0003] In response to the above technical problems, the present invention proposes a method for preventing and controlling geological risks in the construction of a large-span pumped-storage power station tunnel. The pumped-storage power station tunnel is constructed along the inclined rock strata, comprising the following steps:

[0004] a. Determine the expected tunnel location, which is the tunnel location required by the design plan; design the tunnel overbreak location on the side with the relatively high inclination of the tunnel, with the overbreak location located outside the expected tunnel location; and divide the tunnel into three construction areas along the direction of inclination from relatively low to relatively high, namely, the low inclination area, the medium inclination area, and the high inclination area;

[0005] b. Excavate a trench area along the strike of the tunnel on the relatively high-dipping side between the overbreak location and the expected tunnel location; observe a creep characteristic curve for the inclined rock formation on the relatively high-dipping side, with the curve plotted against time and the accumulated creep amount, with the observation point located at the overbreak location in the trench area.

[0006] c. In the low-dip area, construct the tunnel step by step along the strike direction according to the expected tunnel location, with the construction length of each step along the strike direction consistent with the strike length of the groove area constructed in step b. Each construction step includes: excavating the inclined rock layer from top to bottom, and promptly supporting the exposed side sections of the tunnel with steel arches after each layer of inclined rock is excavated; promptly supporting the exposed bottom surface of the tunnel with a bottom plate steel frame and connecting it to the existing steel arch frame;

[0007] d. Obtaining creep characteristic curves and estimating residual creep deformation, which refers to the amount of creep deformation that will occur in the relatively high half-side mid-inclined rock formation beyond the expected position of the tunnel in the later stage;

[0008] e. Filling the groove area in the middle part of the inclined area; in the high-inclined area of ​​the tunnel, gradually construct the tunnel from top to bottom along the strike and expand the outer wall of the groove area, the expansion brush is the residual creep deformation; the length of each construction along the strike is consistent with the strike length of the groove area in step b, and the length of each step is the same as the construction step in step c; each construction step includes: excavating the inclined rock layer by layer from top to bottom and expanding the outer wall of the groove area, the expansion brush is the residual creep deformation, and then constructing the steel arch frame along the expansion brush section, and connecting the bottom plate steel frame along the bottom plate construction;

[0009] f. In the middle area of ​​the tunnel, the tunnel is gradually constructed from top to bottom along the strike, the filling material is removed, and the outer wall of the groove area is expanded and brushed. The length of each construction along the strike is consistent with the strike length of the groove area constructed in step b, and the length of each step is the same as the construction step in step c; each construction step includes: dividing the tunnel horizontally into two layers, first excavating the upper layer, excavating the upper layer twice, first excavating half of the high-inclined area, removing the filling material and expanding the outer wall of the groove area, and the expansion amount is the residual creep deformation; the side section of the tunnel is supported by steel arches and hydraulic supports in time, and connected to the steel arches constructed in the high-inclined area; then excavating half of the low-inclined area, exposing the side section of the tunnel using steel arches and hydraulic supports in time, and connected to the adjacent steel arches constructed in the inclination; then excavating the lower layer, removing the hydraulic supports, and after excavation, constructing the floor steel frame along the bottom plate and connecting the floor steel frames on both sides;

[0010] g. Construction of tunnel concrete lining along the strike direction, with each construction length along the strike direction consistent with the strike length of the grooving area constructed in step b. Construction includes: initial spraying of concrete on the tunnel wall, which covers the steel arch and bottom plate frame, laying of waterproof panels, and then secondary lining construction;

[0011] h. Repeat the above steps until the tunnel is completed.

[0012] Preferably, in step b, the construction length of the grooving area along the strike is 10-15m.

[0013] Preferably, in step c, the construction length of each step is 1.0-1.5m.

[0014] Preferably, step c and step e further include: using hydraulic props to connect the steel arch frame and the bottom plate steel frame closely to the rock mass in the middle inclined area.

[0015] Preferably, in step c, step e, and step f, a steel arch frame and a bottom plate steel frame are constructed in each step, and are located in the middle position of the step.

[0016] The key technical means and beneficial effects of the present invention are:

[0017] The present invention is aimed at constructing a large-span pumped-storage power station tunnel along the strike in an inclined rock formation. The tunnel is divided into three parts along the inclination. First, a groove is cut on the half side with a relatively high inclination. Then, the low-inclination area is excavated and supported in time. During this period, the inclined rock formation outside the grooved area is allowed to creep toward the grooved area. The creep of the rock formation mostly occurs in the initial stage after it is exposed. The inclined rock formation in the high-inclination area can reduce its creep in the later stage by carrying out construction after a large amount of creep has occurred. The residual creep deformation is then obtained based on the creep characteristic curve of the inclined rock formation, so as to accurately expand the high-inclination area and ensure that the tunnel cross-section can still meet the requirements after the final creep deformation of the inclined rock formation. The present invention is particularly suitable for tunnel construction situations where the tunnel cross-section is large and the inclined rock formation is affected by bias pressure. The present invention is simple to construct and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of step a construction of a pumped storage power station tunnel according to the present invention;

[0019] Figure 2 This is a schematic diagram of step b of the construction of the pumped storage power station tunnel of the present invention;

[0020] Figure 3 This is a schematic diagram of step c of the construction of a pumped storage power station tunnel according to the present invention;

[0021] Figure 4 This is a schematic diagram of step e of the construction of a pumped storage power station tunnel according to the present invention;

[0022] Figure 5 This is a schematic diagram of the construction step f of the pumped storage power station tunnel of the present invention Figure 1 ;

[0023] Figure 6 This is a schematic diagram of the construction step f of the pumped storage power station tunnel of the present invention Figure 2 ;

[0024] Figure 7 This is a schematic diagram of the construction step f of the pumped storage power station tunnel of the present invention Figure 3 ;

[0025] Figure 8 It is a schematic diagram of step g of the construction of the pumped storage power station tunnel of the present invention.

[0026] In the figure, 1- inclined rock layer; 2- expected tunnel position; 3- tunnel over-excavation position; 31- tunnel expansion position; 4- cutting area; 5- excavated tunnel area; 6- steel arch frame; 7- bottom plate steel frame; 8- hydraulic support; 9- tunnel lining. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] like Figure 1-8 As shown, a method for preventing and controlling geological risks in the construction of a large-span pumped-storage power station tunnel is provided. The axial direction of the pumped-storage power station tunnel is consistent with the direction of the inclined rock layer 1. The pumped-storage power station tunnel is constructed along the direction of the inclined rock layer. The tunnel is constructed horizontally symmetrically, including the following steps:

[0029] a. Figure 1 As shown, an expected tunnel position 2 is determined, and the expected tunnel position 2 is the tunnel position required according to the design scheme; a tunnel over-excavation position 3 on the half side with a relatively high inclination of the tunnel is designed, and the tunnel over-excavation position 3 is located outside the expected tunnel position 2;

[0030] The tunnel is roughly evenly divided into three construction areas along the direction from relatively low to relatively high inclination, namely low inclination area, medium inclination area and high inclination area;

[0031] b. Figure 2 As shown, on the half side of the tunnel with a relatively high dip, a groove area 4 is excavated along the strike between the tunnel overbreak position 3 and the tunnel expected position 2. The groove excavation is carried out for 10-15 meters along the strike. A creep characteristic curve of the inclined rock stratum 1 on the half side with a relatively high dip is observed. The creep characteristic curve uses time as the abscissa and the accumulated creep amount as the ordinate. The observation point is set at the tunnel overbreak position 3 in the groove area 4.

[0032] c. Figure 3 As shown, in the low-inclination area, the tunnel is constructed step by step along the strike according to the expected tunnel position 2, with each step of construction being 10-15m along the strike, which is consistent with the strike length of the groove area constructed in step b, and the construction length of each step is 1.0-1.5m; the construction content of each step includes: excavating the inclined rock layer 1 layer by layer from top to bottom, and promptly supporting the side section of the exposed tunnel with a steel arch frame 6 after each layer of inclined rock layer 1 is excavated; promptly supporting the bottom surface of the exposed tunnel with a bottom plate steel frame 7, and connecting it with the constructed steel arch frame 6, and using hydraulic pillars 8 to connect the steel arch frame 6 and the bottom plate steel frame 7 in close contact with the rock mass in the middle-inclination area; constructing a steel arch frame 6 and a bottom plate steel frame 7 in each step, located in the middle position of the strike of the step; in this process, the inclined rock layer 1 in the high-inclination area creeps toward the groove area 4;

[0033] d. Obtaining creep characteristic curves and estimating residual creep deformation, which refers to the creep deformation that will be generated in the relatively high half-side mid-inclined rock layer 1 beyond the expected tunnel position 2;

[0034] e. Figure 4 As shown, the groove area 4 in the middle of the inclination zone is filled; in the high inclination zone of the tunnel, the tunnel is gradually constructed from top to bottom along the strike and the outer wall of the groove area 4 is expanded, and the expansion amount is the residual creep deformation; each construction is 10-15m along the strike, which is consistent with the strike length of the groove area constructed in step b, and the construction length of each step is 1.0-1.5m, which is the same as the construction step distance in step c, and the corresponding step distance is consistent along the strike position; the construction content of each step includes: excavating the inclined rock layer 1 layer by layer from top to bottom and expanding the outer wall of the groove area 4, and the expansion amount is the residual creep deformation, then constructing a steel arch frame 6 along the expansion section, constructing a bottom plate steel frame 7 along the bottom plate and connecting the two; using hydraulic pillars 8 to connect the steel arch frame 6 and the bottom plate steel frame 7 close to the rock mass in the middle of the inclination zone; constructing a steel arch frame 6 and a bottom plate steel frame 7 in each step, located in the middle position of the strike of the step;

[0035] f. Figure 5-7 As shown, in the middle area of ​​the tunnel, the tunnel is constructed step by step from top to bottom along the strike, the filling material is removed, and the outer wall of the groove area 4 is expanded and brushed. Each construction is carried out along the strike of 10-15m, which is consistent with the strike length of the groove area constructed in step b. The length of each step is 1.0-1.5m, which is the same as the construction step distance in step c, and the corresponding step distance is consistent along the strike position; the construction content of each step includes: dividing the tunnel horizontally into two layers, first excavating the upper layer, and excavating the upper layer in two times, first excavating the half close to the high-inclined area, removing the filling material and expanding and brushing the outer wall of the groove area 4, The expansion amount is the residual creep deformation amount; the side section of the tunnel is promptly supported by steel arches 6 and hydraulic struts 8, and connected to the steel arches 6 already constructed in the high-inclination area; then the halfway point near the low-inclination area is excavated, and the exposed side section of the tunnel is promptly supported by steel arches 6 and hydraulic struts 8, and connected to the steel arches 6 already constructed in the adjacent inclination area; then the lower layer is excavated, the hydraulic struts 8 are removed, and after excavation, the bottom plate steel frame 7 is constructed along the bottom plate and connected to the bottom plate steel frames 7 on both sides; one steel arch 6 and bottom plate steel frame 7 are constructed at each step, located in the middle of the step;

[0036] g. Such as Figure 8 As shown, the tunnel concrete lining construction is carried out along the strike direction, with each construction being carried out for 10-15m along the strike direction, which is consistent with the strike length of the groove area constructed in step b. The construction content includes: initial spraying of concrete on the tunnel wall, which can cover the steel arch frame 6 and the bottom plate steel frame 7, laying the waterproof board, and then carrying out the secondary lining construction;

[0037] h. Repeat the above steps, i.e., steps a to g, until the tunnel is constructed.

[0038] The present invention is aimed at constructing a large-span pumped-storage power station tunnel along the strike in an inclined rock formation. The tunnel is divided into three parts along the inclination. First, a groove is cut on the half side with a relatively high inclination. Then, the low-inclination area is excavated and supported in time. During this period, the inclined rock formation outside the grooved area is allowed to creep toward the grooved area. The creep of the rock formation mostly occurs in the initial stage after it is exposed. The inclined rock formation in the high-inclination area can reduce its creep in the later stage by carrying out construction after a large amount of creep has occurred. The residual creep deformation is then obtained based on the creep characteristic curve of the inclined rock formation, so as to accurately expand the high-inclination area and ensure that the tunnel cross-section can still meet the requirements after the final creep deformation of the inclined rock formation. The present invention is particularly suitable for tunnel construction situations where the tunnel cross-section is large and the inclined rock formation is affected by bias pressure. The present invention is simple to construct and is easy to promote.

[0039] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above-mentioned embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any technician familiar with this field under the guidance of this specification fall within the substantive scope of this specification and should be protected by the present invention.

Claims

1. A method for preventing and controlling geological risks in the construction of a large-span pumped-storage power station tunnel, wherein the pumped-storage power station tunnel is constructed along an inclined rock stratum, and wherein: The steps include: a. Determine the expected tunnel location, which is the tunnel location required by the design plan; design the tunnel overbreak location on the side with the relatively high inclination of the tunnel, with the overbreak location located outside the expected tunnel location; and divide the tunnel into three construction areas along the direction of inclination from relatively low to relatively high, namely, the low inclination area, the medium inclination area, and the high inclination area; b. Excavate a trench area along the strike of the tunnel on the relatively high-dipping side between the overbreak location and the expected tunnel location; observe a creep characteristic curve for the inclined rock formation on the relatively high-dipping side, with the curve plotted against time and the accumulated creep amount, with the observation point located at the overbreak location in the trench area. c. In the low-dip area, construct the tunnel step by step along the strike direction according to the expected tunnel location, with the construction length of each step along the strike direction consistent with the strike length of the groove area constructed in step b. Each construction step includes: excavating the inclined rock layer from top to bottom, and promptly supporting the exposed side sections of the tunnel with steel arches after each layer of inclined rock is excavated; promptly supporting the exposed bottom surface of the tunnel with a bottom plate steel frame and connecting it to the existing steel arch frame; d. Obtaining creep characteristic curves and estimating residual creep deformation, which refers to the amount of creep deformation that will occur in the relatively high half-side mid-inclined rock formation beyond the expected position of the tunnel in the later stage; e. Filling the groove area in the middle part of the inclined area; in the high-inclined area of ​​the tunnel, gradually construct the tunnel from top to bottom along the strike and expand the outer wall of the groove area, the expansion brush is the residual creep deformation; the length of each construction along the strike is consistent with the strike length of the groove area in step b, and the length of each step is the same as the construction step in step c; each construction step includes: excavating the inclined rock layer by layer from top to bottom and expanding the outer wall of the groove area, the expansion brush is the residual creep deformation, and then constructing the steel arch frame along the expansion brush section, and connecting the bottom plate steel frame along the bottom plate construction; f. In the middle area of ​​the tunnel, the tunnel is gradually constructed from top to bottom along the strike, the filling material is removed, and the outer wall of the groove area is expanded and brushed. The length of each construction along the strike is consistent with the strike length of the groove area constructed in step b, and the length of each step is the same as the construction step in step c; each construction step includes: dividing the tunnel horizontally into two layers, first excavating the upper layer, excavating the upper layer twice, first excavating half of the high-inclined area, removing the filling material and expanding the outer wall of the groove area, and the expansion amount is the residual creep deformation; the side section of the tunnel is supported by steel arches and hydraulic supports in time, and connected to the steel arches constructed in the high-inclined area; then excavating half of the low-inclined area, exposing the side section of the tunnel using steel arches and hydraulic supports in time, and connected to the adjacent steel arches constructed in the inclination; then excavating the lower layer, removing the hydraulic supports, and after excavation, constructing the floor steel frame along the bottom plate and connecting the floor steel frames on both sides; g. Construction of tunnel concrete lining along the strike direction, with each construction length along the strike direction consistent with the strike length of the grooving area constructed in step b. Construction includes: initial spraying of concrete on the tunnel wall, which covers the steel arch and bottom plate frame, laying of waterproof panels, and then secondary lining construction; h. Repeat the above steps until the tunnel is completed.

2. A method for preventing and controlling geological risks in tunnel construction of a large-span pumped storage power station according to claim 1, characterized in that: In step b, the construction length of the grooving area along the strike is 10-15m.

3. A method for preventing and controlling geological risks in tunnel construction of a large-span pumped storage power station according to claim 1, characterized in that: In step c, the construction length of each step is 1.0-1.5m.

4. A method for preventing and controlling geological risks in tunnel construction of a large-span pumped storage power station according to claim 1, characterized in that: Step c and step e also include: using hydraulic props to connect the steel arch frame and the bottom plate steel frame closely to the rock mass in the middle inclined area.

5. A method for preventing and controlling geological risks in tunnel construction of a large-span pumped storage power station according to claim 1, characterized in that: In step c, step e, and step f, a steel arch frame and a bottom plate steel frame are constructed in each step, located in the middle of the step.

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