Large-span pumped storage power station tunnel construction geological risk safety control method

Abstract

The invention relates to the technical field of pumped storage power stations, in particular to a large-span pumped storage power station tunnel construction geological risk safety control method. The large-span pumped storage power station tunnel constructed in the inclined rock stratum in the trend is divided into three parts in the trend direction, firstly, the half side with the relatively high trend is grooved, then a low-trend area is excavated and supported in time, the inclined rock stratum outside the grooving area is made to conduct creep displacement towards the grooving area during the period, and the inclined rock stratum outside the grooving area is cut into the large-span pumped storage power station tunnel. The creep quantity of the rock stratum mostly occurs in the early stage which is just revealed, and the creep quantity of the inclined rock stratum in the high inclination area in the later stage can be reduced after the inclined rock stratum is constructed after a large amount of creep deformation. And then the residual creep deformation amount is obtained according to the creep characteristic curve of the inclined rock stratum, so that the high-inclination area is accurately expanded, and it is guaranteed that the tunnel section can still meet the requirement after final creep deformation of the inclined rock stratum. The method is particularly suitable for tunnel construction conditions that the tunnel section is large and inclined strata are affected by bias pressure, and construction is easy and beneficial to popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of pumped storage power stations, and in particular, to a safety prevention and control method for geological risks in the construction of large-span tunnels of pumped storage power stations. Background Technique

[0002] A pumped storage power station is a hydropower station that pumps water to an upper reservoir using electrical energy during low electricity load periods and releases water to a lower reservoir to generate electricity during high electricity load peaks. Its structure mainly includes an upper reservoir, a lower reservoir, and a tunnel connecting the upper reservoir and the lower reservoir. The tunnels of pumped storage power stations are generally constructed in rock formations, and many rock formations are inclined due to geological activities. When constructing a tunnel in an inclined rock formation, it is easily affected by the bias pressure of the rock formation. After the tunnel is excavated, the rock formation on the relatively high side of the inclination is prone to creep and move into the excavated tunnel, which will cause changes in the cross-sectional size of the tunnel, affecting the accuracy of power regulation in later pumped storage, and will also cause damage to the tunnel support, affecting the long-term safe use of the tunnel. According to different usage functions, the sizes of the tunnels of pumped storage power stations are not the same. For large-section tunnels, the construction difficulty is relatively large, especially when the inclined rock formation is affected by bias pressure. Summary of the Invention

[0003] In view of the above technical problems, the present invention proposes a safety prevention and control method for geological risks in the construction of large-span tunnels of pumped storage power stations. The tunnel of the pumped storage power station is constructed along the strike of the inclined rock formation, and the method includes the following steps:

[0004] a. Determine the expected position of the tunnel, where the expected position of the tunnel is the position of the tunnel required according to the design scheme; design the over-excavation position of the tunnel on the relatively high side of the inclination of the tunnel, and the over-excavation position of the tunnel is located outside the expected position of the tunnel; divide the tunnel into three construction areas along the inclination direction from the relatively low side to the relatively high side, namely the low inclination area, the middle inclination area, and the high inclination area;

[0005] b. On the relatively high side of the inclination of the tunnel, excavate the cutting groove area between the over-excavation position of the tunnel and the expected position of the tunnel along the strike; observe the creep characteristic curve of the inclined rock formation on the relatively high side of the inclination, where the creep characteristic curve takes time as the abscissa and the cumulative creep amount as the ordinate, and the observation points are set at the over-excavation position of the tunnel in the cutting groove area;

[0006] c. In the low inclination area, construct the tunnel step by step along the strike according to the expected position of the tunnel, and the length of each construction along the strike is the same as the strike length of the cutting groove area constructed in step b; each step of construction content includes: excavating the inclined rock formation layer by layer from top to bottom, and timely supporting the side section of the exposed tunnel with steel arch frames after each layer of the inclined rock formation is excavated; timely supporting the bottom surface of the exposed tunnel with a bottom plate steel frame and connecting it to the already constructed steel arch frames;

[0007] d. Obtain the creep characteristic curve and estimate the residual creep deformation amount, where the residual creep deformation amount refers to the creep deformation amount that the inclined rock stratum in the relatively high half will generate later and exceed the expected position of the tunnel.

[0008] e. Fill the grooving area in the middle part of the inclined area; in the high inclined area of the tunnel, construct the tunnel step by step from top to bottom along the strike and brush the outer wall of the grooving area, and the brushing amount is the residual creep deformation amount; the length of each construction along the strike is the same as the strike length of the grooving area constructed in step b, and the construction step length of each step is the same as the construction step distance in step c; the construction content of each step includes: excavate the inclined rock stratum layer by layer from top to bottom and brush the outer wall of the grooving area, and the brushing amount is the residual creep deformation amount, then construct the steel arch frame along the brushed section, construct the bottom steel frame along the bottom plate and connect the two.

[0009] f. In the middle inclined area of the tunnel, construct the tunnel step by step from top to bottom along the strike, take out the filling material, and brush the outer wall of the grooving area. The length of each construction along the strike is the same as the strike length of the grooving area constructed in step b, and the construction step length of each step is the same as the construction step distance in step c; the construction content of each step includes: horizontally divide the tunnel into two layers, first excavate the upper layer, and the upper layer is excavated in two times. First, excavate the half close to the high inclined area, take out the filling material and brush the outer wall of the grooving area, and the brushing amount is the residual creep deformation amount; timely support the side section of the tunnel with a steel arch frame and a hydraulic support and connect it with the steel arch frame constructed in the high inclined area; then excavate the half close to the low inclined area, timely support the exposed side section of the tunnel with a steel arch frame and a hydraulic support and connect it with the adjacent constructed steel arch frame in the inclined direction; then excavate the lower layer, remove the hydraulic support, and construct the bottom steel frame along the bottom plate after excavation and connect it with the bottom steel frames on both sides.

[0010] g. Carry out tunnel concrete lining construction along the strike. The length of each construction along the strike is the same as the strike length of the grooving area constructed in step b. The construction content includes: initially spray concrete on the tunnel wall surface, and the initially sprayed concrete can cover the steel arch frame and the bottom steel frame. After laying the waterproof board, carry out secondary lining construction.

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

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

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

[0014] Preferably, in steps c and e, it further includes: connecting the steel arch frame and the bottom steel frame with a hydraulic support closely attached to the rock mass in the middle inclined area.

[0015] Preferably, in step c, step e, and step f, one steel arch and one floor steel frame are constructed in each step, located at the middle position of the alignment of that step.

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

[0017] The present invention is directed to a large-span pumped-storage power station tunnel constructed along the alignment in inclined rock strata. It divides the tunnel along the dip into three parts. First, a half-cut groove is made on the relatively higher-dip half. Then, the lower-dip area is excavated and timely supported. During this period, the inclined rock strata outside the cut groove area creep and displace towards the cut groove area. Most of the creep amount of the rock strata occurs in the initial stage of exposure. After a large amount of creep occurs in the higher-dip inclined rock strata, construction can be carried out to reduce its later creep amount. Then, the residual creep deformation amount is obtained according to the creep characteristic curve of the dip rock strata, so as to accurately expand and brush the higher-dip area to ensure that the tunnel section can still meet the requirements after the final creep deformation of the inclined rock strata. The present invention is particularly applicable to the tunnel construction situation where the tunnel section is large and the inclined rock strata are affected by bias pressure. The construction of the present invention is simple and conducive to popularization. Description of the Drawings

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

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

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

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

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

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

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

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

[0026] In the figure, 1 - inclined rock stratum; 2 - expected position of the tunnel; 3 - overexcavated position of the tunnel; 31 - enlarged and brushed position of the tunnel; 4 - grooving area; 5 - excavated tunnel area; 6 - steel arch frame; 7 - floor steel frame; 8 - hydraulic support; 9 - tunnel lining. Specific implementation manner

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

[0028] As Figure 1-8 shown, for the geological risk safety prevention and control method for the construction of a large-span pumped-storage power station tunnel, the axial direction of the pumped-storage power station tunnel is consistent with the strike of the inclined rock stratum 1, the pumped-storage power station tunnel is constructed along the strike of the inclined rock stratum, and the tunnel is constructed symmetrically horizontally, including the following steps:

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

[0030] Divide the tunnel into three construction areas approximately evenly along the inclination direction from the relatively low inclination to the relatively high inclination, namely the low-inclination area, the middle-inclination area, and the high-inclination area;

[0031] b. As Figure 2 shown, on the relatively high-inclination half side of the tunnel, excavate the grooving area 4 between the overexcavated position 3 of the tunnel and the expected position 2 of the tunnel along the strike, and the grooving work is constructed along the strike for 10 - 15 m; observe the creep characteristic curve of the inclined rock stratum 1 in the relatively high-inclination half side, the creep characteristic curve takes time as the abscissa and the cumulative creep displacement as the ordinate, and the observation points are set at the overexcavated position 3 of the tunnel in the grooving area 4;

[0032] c. As Figure 3 shown, in the low-inclination area, construct the tunnel step by step along the strike according to the expected position 2 of the tunnel, each time construct 10 - 15 m along the strike, which is the same as the strike length of the grooving area constructed in step b, and the length of each step of construction is 1.0 - 1.5 m; the content of each step of construction includes: excavate the inclined rock stratum 1 layer by layer from top to bottom, and after excavating each layer of the inclined rock stratum 1, timely support the exposed side section of the tunnel with the steel arch frame 6; timely support the exposed bottom surface of the tunnel with the floor steel frame 7, and connect it with the already constructed steel arch frame 6, and use the hydraulic support 8 to closely connect the steel arch frame 6 and the floor steel frame 7 to the rock mass in the middle-inclination area; construct one steel arch frame 6 and floor steel frame 7 for each step, which is located at the middle position of the strike of this step; during this process, the inclined rock stratum 1 in the high-inclination area creeps and displaces towards the grooving area 4;

[0033] d. Obtain the creep characteristic curve and estimate the residual creep deformation amount, where the residual creep deformation amount refers to the creep deformation amount that the inclined rock stratum 1 on the relatively high side will still generate later and exceed the expected position 2 of the tunnel.

[0034] e. As Figure 4 shown, fill the grooving area 4 in the middle part of the inclined area; in the high inclined area of the tunnel, construct the tunnel step by step from top to bottom along the strike and expand and brush the outer wall of the grooving area 4, and the expansion and brushing amount is the residual creep deformation amount; construct 10 - 15 m along the strike each time, which is the same as the strike length of the grooving area constructed in step b, and the construction length of each step is 1.0 - 1.5 m, which is the same as the construction step distance in step c, and the corresponding step distance positions are the same along the strike; the construction content of each step includes: excavate the inclined rock stratum 1 layer by layer from top to bottom and expand and brush the outer wall of the grooving area 4, and the expansion and brushing amount is the residual creep deformation amount, then construct the steel arch 6 along the expanded section, construct the floor steel frame 7 along the floor and connect the two; use the hydraulic support 8 to closely connect the steel arch 6 and the floor steel frame 7 to the inclined middle rock mass; construct one steel arch 6 and one floor steel frame 7 for each step, which are located in the middle position of the strike of this step.

[0035] f. As Figures 5-7 shown, in the middle inclined area of the tunnel, construct the tunnel step by step from top to bottom along the strike, take out the filling material, and expand and brush the outer wall of the grooving area 4. Construct 10 - 15 m along the strike each time, which is the same as the strike length of the grooving area constructed in step b, and the construction length of each step is 1.0 - 1.5 m, which is the same as the construction step distance in step c, and the corresponding step distance positions are the same along the strike; the construction content of each step includes: horizontally divide the tunnel into two layers, first excavate the upper layer, and the upper layer is excavated in two times. First, excavate the half close to the high inclined area, take out the filling material and expand and brush the outer wall of the grooving area 4, and the expansion and brushing amount is the residual creep deformation amount; timely support the side section of the tunnel with the steel arch 6 and the hydraulic support 8 and connect it to the steel arch 6 constructed in the high inclined area; then excavate the half close to the low inclined area, timely support the exposed side section of the tunnel with the steel arch 6 and the hydraulic support 8 and connect it to the adjacent constructed steel arch 6 in the inclined direction; then excavate the lower layer, remove the hydraulic support 8, and construct the floor steel frame 7 along the floor after excavation and connect it to the floor steel frames 7 on both sides; construct one steel arch 6 and one floor steel frame 7 for each step, which are located in the middle position of the strike of this step.

[0036] g. As Figure 8 shown, carry out tunnel concrete lining construction along the strike. Construct 10 - 15 m along the strike each time, which is the same as the strike length of the grooving area constructed in step b. The construction content includes: initially spray concrete on the tunnel wall surface, and the initially sprayed concrete can cover the steel arch 6 and the floor steel frame 7, and then carry out secondary lining construction after laying the waterproof board.

[0037] h. Repeat the above steps, that is, steps a to g, until the tunnel construction is completed.

[0038] The present invention is directed to a large-span pumped-storage power station tunnel constructed along the strike in inclined rock strata. The tunnel is divided into three parts along the dip direction. First, a semi-side cutting groove is made in the relatively higher-dip half, and then the lower-dip area is excavated and timely supported. During this period, the inclined rock strata outside the cutting groove area creep and displace towards the cutting groove area. Most of the creep amount of the rock strata occurs in the initial stage of exposure. After a large amount of creep occurs in the inclined rock strata in the higher-dip area, construction can be carried out to reduce its later creep amount. Then, the residual creep deformation amount is obtained according to the creep characteristic curve of the inclined rock strata, so as to accurately expand and brush the higher-dip area to ensure that the tunnel section can still meet the requirements after the final creep deformation of the inclined rock strata. The present invention is particularly suitable for tunnel construction situations where the tunnel section is large and the inclined rock strata are affected by eccentric pressure. The construction of the present invention is simple and conducive to popularization.

[0039] Of course, the above description is only a preferred embodiment of the present invention. The present invention is not limited to listing the above embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any person skilled in the art under the guidance of this specification fall within the substantial scope of this specification and should be protected by the present invention.

Claims

1. A safety prevention and control method for geological risks in the construction of tunnels in large-span pumped-storage power stations. The tunnels of the pumped-storage power station are constructed along the strike of inclined rock strata, and it is characterized in that, It includes the following steps: a. Determine the expected position of the tunnel, where the expected position of the tunnel is the tunnel position required according to the design scheme; design the over-excavated position of the tunnel on the relatively high-side of the tunnel inclination, and the over-excavated position of the tunnel is located outside the expected position of the tunnel; divide the tunnel into three construction areas along the inclination direction from the relatively low inclination to the relatively high inclination, namely the low-inclination area, the middle-inclination area, and the high-inclination area; b. In the relatively high-side of the tunnel inclination, excavate the cutting area between the over-excavated position of the tunnel and the expected position of the tunnel along the tunnel alignment; observe the creep characteristic curve of the inclined rock stratum in the relatively high-side of the tunnel inclination, where the creep characteristic curve takes time as the abscissa and the cumulative creep deformation as the ordinate, and the observation points are set at the over-excavated position of the tunnel in the cutting area; c. In the low-inclination area, construct the tunnel step by step along the tunnel alignment according to the expected position of the tunnel, and the length of each construction along the tunnel alignment is the same as the length of the cutting area alignment constructed in step b; the construction content of each step includes: excavate the inclined rock stratum layer by layer from top to bottom, and timely support the side section of the exposed tunnel with steel arch frames after each excavation of an inclined rock stratum; timely support the bottom of the exposed tunnel with a bottom steel frame and connect it to the already constructed steel arch frames; d. Obtain the creep characteristic curve and estimate the residual creep deformation amount, where the residual creep deformation amount refers to the creep deformation amount that will still be generated by the inclined rock stratum in the relatively high-side later and exceeds the expected position of the tunnel; e. Fill the cutting area in the middle-inclination area; in the high-inclination area of the tunnel, construct the tunnel step by step from top to bottom along the tunnel alignment and expand and brush the outer wall of the cutting area, and the expansion and brushing amount is the residual creep deformation amount; the length of each construction along the tunnel alignment is the same as the length of the cutting area alignment constructed in step b, and the construction step length is the same as the construction step distance in step c; the construction content of each step includes: excavate the inclined rock stratum layer by layer from top to bottom and expand and brush the outer wall of the cutting area, and the expansion and brushing amount is the residual creep deformation amount, then construct the steel arch frames along the expanded section, construct the bottom steel frames along the bottom plate and connect the two; f. In the middle-inclination area of the tunnel, construct the tunnel step by step from top to bottom along the tunnel alignment, remove the filling material, and expand and brush the outer wall of the cutting area. The length of each construction along the tunnel alignment is the same as the length of the cutting area alignment constructed in step b, and the construction step length is the same as the construction step distance in step c; the construction content of each step includes: horizontally divide the tunnel into two layers, first excavate the upper layer, and the upper layer is excavated in two times. First, excavate the half close to the high-inclination area, remove the filling material and expand and brush the outer wall of the cutting area, and the expansion and brushing amount is the residual creep deformation amount; timely support the side section of the tunnel with steel arch frames and hydraulic supports and connect it to the already constructed steel arch frames in the high-inclination area; then excavate the half close to the low-inclination area, timely support the side section of the exposed tunnel with steel arch frames and hydraulic supports and connect it to the already constructed steel arch frames adjacent to the inclination; then excavate the lower layer, remove the hydraulic supports, and construct the bottom steel frames along the bottom plate after excavation and connect them to the bottom steel frames on both sides; g. Tunnel concrete lining construction is carried out along the strike. Each time the construction length along the strike is the same as the strike length of the grooving area constructed in step b. The construction content includes: initially spraying concrete on the tunnel wall surface, and the initially sprayed concrete can cover the steel arch and the floor steel frame. After laying the waterproof board, secondary lining construction is carried out; h. Repeat the above steps until the tunnel construction is completed.

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

3. A geological risk safety prevention and control method for the 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 - 1.5 m.

4. A geological risk safety prevention and control method for the construction of a large-span pumped storage power station tunnel according to claim 1, characterized in that, In steps c and e, it also includes: using hydraulic struts to closely connect the steel arch and the floor steel frame to the rock mass in the dip middle area.

5. A geological risk safety prevention and control method for the tunnel construction of a large-span pumped storage power station according to claim 1, characterized in that, In steps c, e, and f, one steel arch and one floor steel frame are constructed in each step, which are located at the middle position of the strike of this step.

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