Ultra-deep overburden dam foundation anti-seepage system and construction method thereof

Abstract

The present invention provides an ultra-deep overburden dam foundation anti-seepage system and a construction method thereof. Since the elastic modulus of the slurry in the grouting area is between the elastic modulus of the anti-seepage wall and the elastic modulus of the dam foundation, the grouting area can act as a transition layer between the anti-seepage wall and the ultra-deep overburden in earthquake conditions to buffer the anti-seepage wall, thereby reducing the deformation of the anti-seepage wall and the stress on the anti-seepage wall on the one hand, and avoiding the hollowing phenomenon between the anti-seepage wall and the ultra-deep overburden due to the earthquake on the other hand, thereby avoiding the reduction of the anti-seepage effect of the dam foundation or even the failure of the anti-seepage effect of the dam foundation; and the grouting area can form flexible anti-seepage structures on both sides of the upstream and downstream of the anti-seepage wall, respectively, so as to further improve the anti-seepage effect of the dam foundation on the basis of the anti-seepage effect of the anti-seepage wall, thereby realizing the anti-seepage of the ultra-deep overburden dam foundation, thereby avoiding the occurrence of seepage damage to the dam foundation due to construction defects of the anti-seepage wall and the like.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy and hydropower engineering, and in particular to an ultra-deep overburden dam foundation anti-seepage system and a construction method thereof. Background Art

[0002] Earth-rock dams are a common type of dam used in the construction of water conservancy and hydropower projects. When an earth-rock dam is built on a dam foundation with a thick overburden layer, the bearing capacity of the dam foundation is usually sufficient, and the settlement caused by the compression of the dam foundation is generally not large. The treatment of the thick overburden layer is mainly to solve the problem of anti-seepage, and the purpose of controlling the seepage of the dam foundation is achieved by taking measures combining "upper blocking" and "lower drainage".

[0003] There are two main treatment measures for anti-seepage of dam foundation with deep overburden layer: horizontal anti-seepage and vertical anti-seepage. Among them, horizontal anti-seepage measures generally place materials such as concrete, clay or geomembrane on the upstream dam foundation and connect them to the dam to extend the seepage path of the dam foundation so that the seepage gradient does not exceed the allowable value. It is generally suitable for medium and low dams on dam foundations with relatively simple homogeneous or double-layer overburden layers, while for high dams, it is generally necessary to combine it with vertical anti-seepage measures. Vertical anti-seepage is the most effective measure to control the seepage of highly permeable dam foundations. Vertical anti-seepage technology is relatively mature and is the most reliable and widespread in foundation treatment applications of water conservancy projects. Its main structural types include concrete anti-seepage walls and grouting curtains, as well as the combination of the two.

[0004] In recent years, the improvement results of the vertical anti-seepage treatment method of traditional earth-rock dam foundation for deep overburden layer mainly include:

[0005] 1) The invention patent with publication number CN106894389A proposes a new anti-seepage system and structure suitable for earth-rock dams with deep overburden layers. Vertical and horizontal anti-seepage structures are provided in the dam foundation at the same time. The vertical anti-seepage wall and curtain grouting extend to a depth below the stratum that meets the anti-seepage requirements; a horizontal anti-seepage layer is provided in the upstream direction of the dam foundation surface elevation, the vertical and horizontal anti-seepage structures intersect near the dam axis, and a horizontal drainage layer is provided downstream of the dam foundation along the ground elevation.

[0006] 2) The invention patent with publication number CN105155472A proposes an anti-seepage structure for the foundation of an earth-rock dam with a deep overburden layer and a construction method thereof, wherein the anti-seepage structure for the foundation of an earth-rock dam with a deep overburden layer comprises a suspended cast-in-place wall section and a grouting section; the lower part of the suspended cast-in-place wall section extends into a relatively impermeable layer in the overburden layer, and its upper end is connected to a grouting gallery; the grouting section is arranged in the overburden layer and the bedrock, and its upper and lower ends are respectively connected to the suspended cast-in-place wall section and the bedrock; a pre-buried first grouting pipe for constructing the grouting section is arranged upstream and downstream in the suspended cast-in-place wall section, and the upper end of the pre-buried first grouting pipe is connected to the inner cavity of the grouting gallery, and the lower end is located at the bottom of the suspended cast-in-place wall section.

[0007] 3) The invention patent with publication number CN117845835A proposes an ultra-high pressure rotary jet grouting pile auxiliary anti-seepage method for the anti-seepage wall of a high earth-rock dam with thick covering layer. By setting ultra-high pressure rotary jet grouting bite piles, the strength of the soil in the upstream and downstream covering layers is enhanced to form a more stable anti-seepage system and reduce the stress of the concrete anti-seepage wall. At the same time, the ultra-high pressure rotary jet grouting bite piles themselves are anti-seepage bodies, which can assist in anti-seepage and improve the anti-seepage effect of high earth-rock dam with thick covering layer.

[0008] 4) The invention patent with publication number CN116641344A proposes a double-row anti-seepage structure of a thick covering layer, in which the front row of anti-seepage walls penetrates the thick covering layer, and the top is connected to the anti-seepage body of the core wall rockfill dam, and the bottom extends into the bedrock layer, thereby forming the first anti-seepage defense line from upstream to downstream, playing the first anti-seepage role; the rear row of anti-seepage walls also penetrates the thick covering layer, and the top is connected to the corridor, and the bottom is connected to the curtain grouting structure, thereby forming the second anti-seepage defense line behind the front row of anti-seepage walls, playing the second anti-seepage role.

[0009] Although the above technologies have proposed improvement plans for the anti-seepage technology of earth-rock dam foundations with deep overburden, the existing technologies still have the following shortcomings: for high-seismic areas, under earthquake conditions, when an earth-rock dam is built on a super-deep overburden foundation with a depth of more than 100m, the anti-seepage wall of the super-deep overburden foundation of the earth-rock dam and the soil often breaks due to excessive and uneven force, resulting in seepage damage to the dam foundation; the anti-seepage wall of the super-deep overburden foundation of the earth-rock dam often leads to seepage damage to the dam foundation due to construction defects; the current anti-seepage technology is difficult to achieve anti-seepage of the super-deep overburden foundation of the earth-rock dam. Summary of the invention

[0010] In view of this, an object of the present invention is to provide an ultra-deep overburden dam foundation anti-seepage system and a construction method thereof, so as to alleviate the above-mentioned shortcomings existing in the prior art.

[0011] In a first aspect, an embodiment of the present invention provides an ultra-deep overburden dam foundation anti-seepage system, wherein the ultra-deep overburden dam foundation anti-seepage system is arranged in an ultra-deep overburden, and the ultra-deep overburden dam foundation anti-seepage system comprises an anti-seepage wall vertically arranged in the dam foundation along the dam axis direction, and grouting areas respectively arranged on the upstream and downstream sides of the anti-seepage wall; the anti-seepage wall is perpendicular to the flow direction of the water flow, the grouting area is arranged along the axis direction of the anti-seepage wall, the upper end elevation of the grouting area is consistent with the top elevation of the anti-seepage wall, and the grouting area extends into the first target layer; the first The target layer is a relatively impermeable soil layer in the ultra-deep covering layer or a bedrock below the ultra-deep covering layer; the elastic modulus of the slurry used for constructing the grouting area is between the elastic modulus of the cut-off wall and the elastic modulus of the dam foundation; the top of the cut-off wall is connected to the anti-seepage structure of the earth-rock dam body; the bottom of the cut-off wall extends into the first target layer; the bedrock is located below the ultra-deep covering layer, and the permeability coefficient of the relatively impermeable soil layer is less than the permeability coefficients of other soil layers above and below the ultra-deep covering layer that are adjacent to the relatively impermeable soil layer.

[0012] In a second aspect, an embodiment of the present invention further provides an ultra-deep overburden dam foundation anti-seepage system, wherein the ultra-deep overburden dam foundation anti-seepage system is arranged in an ultra-deep overburden, and the ultra-deep overburden dam foundation anti-seepage system comprises an anti-seepage wall vertically arranged in the dam foundation along the dam axis direction, and grouting areas respectively arranged on the upstream and downstream sides of the anti-seepage wall; the anti-seepage wall is perpendicular to the flow direction of the water flow, the grouting area is arranged along the axial direction of the anti-seepage wall, the upper end elevation of the grouting area is consistent with the top elevation of the anti-seepage wall, and the grouting area extends into the bedrock below the ultra-deep overburden; and the grouting area is used for constructing the grouting area. The elastic modulus of the slurry in the slurry zone is between the elastic modulus of the anti-seepage wall and the elastic modulus of the dam foundation; the top of the anti-seepage wall is connected to the anti-seepage structure of the earth-rock dam body; the bottom of the anti-seepage wall is connected to a curtain grouting body, and the bottom of the curtain grouting body extends into the second target layer; the second target layer is a permeability control layer or a relatively impermeable rock layer in the bedrock; the permeability of the permeability control layer is a preset permeability value corresponding to the dam foundation anti-seepage, and the permeability coefficient of the relatively impermeable rock layer is less than the permeability coefficient of other rock layers in the bedrock that are adjacent to the relatively impermeable rock layer above and below.

[0013] In a third aspect, an embodiment of the present invention further provides a construction method for an ultra-deep overburden layer dam foundation anti-seepage system, the construction method being used to construct the ultra-deep overburden layer dam foundation anti-seepage system described in the first aspect above, the construction method comprising: constructing the anti-seepage wall and connecting the top of the anti-seepage wall with the anti-seepage structure of the earth-rock dam body; constructing the grouting area after the construction of the anti-seepage wall is completed, and obtaining the ultra-deep overburden layer dam foundation anti-seepage system after the construction of the grouting area is completed.

[0014] In a fourth aspect, an embodiment of the present invention further provides a construction method for an ultra-deep overburden layer dam foundation anti-seepage system, the construction method being used to construct the ultra-deep overburden layer dam foundation anti-seepage system described in the second aspect, the construction method comprising: constructing the anti-seepage wall, and connecting the top of the anti-seepage wall with the anti-seepage structure of the earth-rock dam body; after the construction of the anti-seepage wall is completed, constructing the curtain grouting body, and then constructing the grouting area, and obtaining the ultra-deep overburden layer dam foundation anti-seepage system after the construction of the grouting area is completed.

[0015] An embodiment of the present invention provides an ultra-deep overburden dam foundation anti-seepage system and a construction method thereof. Since the elastic modulus of the slurry in the grouting area is between the elastic modulus of the anti-seepage wall and the elastic modulus of the dam foundation, the grouting area can act as a transition layer between the anti-seepage wall and the ultra-deep overburden under earthquake conditions to buffer the anti-seepage wall, thereby reducing the deformation of the anti-seepage wall and the stress on the anti-seepage wall on the one hand, and avoiding the hollowing phenomenon between the anti-seepage wall and the ultra-deep overburden due to the earthquake on the other hand, thereby avoiding the reduction of the anti-seepage effect of the dam foundation or even the failure of the anti-seepage effect of the dam foundation; and the grouting area can form flexible anti-seepage structures on both sides of the upstream and downstream of the anti-seepage wall, respectively, so as to further improve the anti-seepage effect of the dam foundation on the basis of the anti-seepage effect of the anti-seepage wall, thereby realizing the anti-seepage of the ultra-deep overburden dam foundation, thereby avoiding the occurrence of seepage damage to the dam foundation due to defects in the construction of the anti-seepage wall and the like.

[0016] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a structural schematic diagram of an ultra-deep overburden dam foundation anti-seepage system in an embodiment of the present invention;

[0020] Figure 2 This is an example diagram of an ultra-deep overburden dam foundation anti-seepage system in an embodiment of the present invention;

[0021] Figure 3 This is an exemplary diagram of another ultra-deep overburden dam foundation anti-seepage system in an embodiment of the present invention;

[0022] Figure 4 This is a construction drawing of controllable paste grouting in stages in an embodiment of the present invention;

[0023] Figure 5 This is a construction drawing of curtain grouting in stages in an embodiment of the present invention;

[0024] Figure 6 This is an example diagram of the overall model of the dam in the embodiment of the present invention;

[0025] Figure 7 It is a model example diagram of the dam shell, clay core wall, concrete cut-off wall, and controllable grout grouting structure in the embodiment of the present invention;

[0026] Figures 8 to 9 They are respectively displacement cloud diagrams of X- and Z-direction seismic strain responses of the concrete anti-seepage wall in the anti-seepage solution with a controllable paste grouting structure in the embodiment of the present invention;

[0027] Figures 10 to 12 They are respectively stress distribution diagrams of seismic stress responses of the concrete anti-seepage wall in the X, Y, and Z directions in the anti-seepage solution with a controllable paste grouting structure in the embodiment of the present invention;

[0028] Figure 13 to Figure 14 They are respectively displacement cloud diagrams of X- and Z-direction seismic strain responses of the concrete anti-seepage wall in the anti-seepage solution without the controllable paste grouting structure in the embodiment of the present invention;

[0029] Figures 15 to 17 They are respectively stress distribution diagrams of the seismic stress response of the concrete anti-seepage wall in the X, Y and Z directions in the anti-seepage solution without the controllable paste grouting structure in the embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in combination with the embodiments below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] At present, the anti-seepage technology for the foundation of earth-rock dams with deep overburden has the following shortcomings: for high-seismic areas, under earthquake conditions, when the earth-rock dam is built on the dam foundation of ultra-deep overburden with a depth of more than 100m, the anti-seepage wall of the dam foundation of the ultra-deep overburden layer of the earth-rock dam and the soil often breaks due to excessive and uneven force, resulting in seepage damage to the dam foundation; the anti-seepage wall of the dam foundation of the ultra-deep overburden layer of the earth-rock dam often leads to seepage damage to the dam foundation due to construction defects; the current anti-seepage technology is difficult to achieve anti-seepage of the dam foundation of the ultra-deep overburden layer of the earth-rock dam.

[0032] Based on this, the present invention provides an ultra-deep overburden dam foundation anti-seepage system and a construction method thereof, which can alleviate the above-mentioned shortcomings existing in the prior art.

[0033] To facilitate understanding of this embodiment, firstly, a super-deep overburden dam foundation anti-seepage system disclosed in an embodiment of the present invention is introduced in detail.

[0034] The embodiment of the invention provides a first ultra-deep overburden dam foundation anti-seepage system, see Figure 1 As shown, the ultra-deep overburden dam foundation anti-seepage system is set in the ultra-deep overburden 30, and the ultra-deep overburden dam foundation anti-seepage system may include an anti-seepage wall 10 vertically set in the dam foundation along the dam axis direction and grouting areas 20 respectively set on the upstream and downstream sides of the anti-seepage wall 10; the anti-seepage wall 10 is perpendicular to the flow direction of the water flow, the grouting area 20 is set along the axis direction of the anti-seepage wall 10, the upper end elevation of the grouting area 20 is consistent with the top elevation of the anti-seepage wall 10, and the grouting area 20 extends into the first target layer; the elastic modulus of the slurry used to construct the grouting area 20 is between the elastic modulus of the anti-seepage wall 10 and the elastic modulus of the dam foundation; the top of the anti-seepage wall 10 is connected to the anti-seepage structure of the earth-rock dam 50; the bottom of the anti-seepage wall 10 extends into the first target layer. Among them, the earth-rock dam 50 may include a core wall dam, a sloping wall dam, a face rockfill dam, a homogeneous earth dam, etc., which are not limited. The anti-seepage structure of the earth-rock dam 50 serves as the top connection structure of the anti-seepage wall 10 , and its type can be flexibly selected according to the dam type, and there is no limitation on this.

[0035] See also Figure 2 As shown, if the ultra-deep cover layer 30 contains a relatively impermeable soil layer, the first target layer may be the relatively impermeable soil layer 40 in the ultra-deep cover layer 30, and the permeability coefficient of the relatively impermeable soil layer 40 is smaller than the permeability coefficients of other soil layers in the ultra-deep cover layer 30 that are adjacent to the relatively impermeable soil layer 40 above and below. Figure 3 As shown, if the bedrock 100 below the ultra-deep overburden 30 is buried at a shallow depth, the first target layer may be the bedrock 100 .

[0036] The first ultra-deep overburden dam foundation anti-seepage system provided by the embodiment of the present invention has an elastic modulus of slurry in the grouting area between the elastic modulus of the anti-seepage wall and the elastic modulus of the dam foundation. Therefore, the grouting area can act as a transition layer between the anti-seepage wall and the ultra-deep overburden under earthquake conditions to buffer the anti-seepage wall, thereby reducing the deformation of the anti-seepage wall and the stress on the anti-seepage wall on the one hand, and avoiding the voiding phenomenon between the anti-seepage wall and the ultra-deep overburden due to the earthquake on the other hand, thereby avoiding the reduction of the anti-seepage effect of the dam foundation or even the failure of the anti-seepage effect of the dam foundation; and the grouting area can form flexible anti-seepage structures on both sides of the upstream and downstream of the anti-seepage wall, respectively, so as to further improve the anti-seepage effect of the dam foundation on the basis of the anti-seepage effect of the anti-seepage wall, thereby realizing the anti-seepage of the ultra-deep overburden dam foundation, thereby avoiding the occurrence of seepage damage to the dam foundation due to defects in the construction of the anti-seepage wall and the like.

[0037] As a possible implementation, see Figure 2 As shown, in the case where the ultra-deep cover layer 30 contains a relatively impermeable soil layer, the bottom of the cut-off wall 10 can extend into the relatively impermeable soil layer 40, and the depth of the bottom of the cut-off wall 10 extending into the relatively impermeable soil layer 40 is not less than a first preset value. The first preset value can be customized according to actual construction requirements. With this structural design, it is possible to ensure that the bottom of the cut-off wall 10 is in full contact with the relatively impermeable soil layer 40, thereby making full use of the relatively low permeability coefficient of the relatively impermeable soil layer 40 to ensure the overall anti-seepage effect of the cut-off wall 10.

[0038] As a possible implementation, see Figure 2 As shown, the bottom of the anti-seepage wall 10 can be connected to a plugging body 21; the upstream side and the downstream side of the anti-seepage wall 10 are respectively provided with a first grouting pipe for constructing the grouting area 20 vertically along the dam axis direction, the upper end of the first grouting pipe is connected to the earth-rock dam 50, and the lower end of the first grouting pipe is connected to the plugging body 21. With this structural design, the firmness of the connection between the anti-seepage wall 10 and the earth-rock dam 50 can be ensured by the anti-seepage structure of the earth-rock dam 50, and the stability of the grouting construction of the grouting area 20 can be ensured by the first grouting pipe and the plugging body 21, so as to ensure the anti-seepage effect of the grouting area 20 while ensuring the construction stability of the anti-seepage wall 10.

[0039] As a possible implementation, see Figure 2 As shown, the top of the plugging body 21 is connected to the bottom of the anti-seepage wall 10, and the vertical distance between the bottom of the plugging body 21 and the bottom of the anti-seepage wall 10 is not less than the fourth preset value. Among them, the fourth preset value can be customized according to actual construction requirements. With this structural design, it can be ensured that the plugging body 21 fully extends into the ultra-deep cover layer 30, thereby ensuring the stability of the grouting operation of the first grouting pipe connected to the plugging body 21, thereby further ensuring the stability of the construction of the anti-seepage wall 10 and the anti-seepage effect of the grouting area 20.

[0040] against Figure 3In the case where the bedrock 100 below the ultra-deep overburden 30 is buried at a shallow depth, the embodiment of the present invention also provides a first ultra-deep overburden dam foundation anti-seepage system, see Figure 1 and Figure 3 As shown, the ultra-deep overburden dam foundation anti-seepage system is arranged in the ultra-deep overburden 30, and the ultra-deep overburden dam foundation anti-seepage system may include an anti-seepage wall 10 vertically arranged in the dam foundation along the dam axis direction and grouting areas 20 respectively arranged on the upstream and downstream sides of the anti-seepage wall 10; the anti-seepage wall 10 is perpendicular to the flow direction of the water flow, the grouting area 20 is arranged along the axial direction of the anti-seepage wall 10, the upper end elevation of the grouting area 20 is consistent with the top elevation of the anti-seepage wall 10, and the grouting area 20 extends into the bedrock 100 located below the ultra-deep overburden; the elastic modulus of the slurry used to construct the grouting area 20 is between the elastic modulus of the anti-seepage wall 10 and the elastic modulus of the dam foundation; the top of the anti-seepage wall 10 is connected to the anti-seepage structure of the earth-rock dam 50; the bottom of the anti-seepage wall 10 is connected to a curtain grouting body 110 (i.e., a curtain obtained by curtain grouting construction), and the bottom of the curtain grouting body 110 extends into the second target layer. The second target layer may be a permeability control layer 42 or a relatively impermeable rock layer 43 in the bedrock 100; the permeability of the permeability control layer 42 is a preset permeability value corresponding to the dam foundation anti-seepage, and the permeability coefficient of the relatively impermeable rock layer 43 is less than the permeability coefficients of other rock layers in the bedrock 100 that are adjacent to the relatively impermeable rock layer 43 above and below. The permeability control layer 42 may refer to a rock layer in the bedrock 100 whose permeability is a preset permeability value.

[0041] The technical effect of the second ultra-deep overburden dam foundation anti-seepage system provided in the embodiment of the present invention is similar to the technical effect of the first ultra-deep overburden dam foundation anti-seepage system mentioned above, which will not be described in detail.

[0042] As a possible implementation, see Figure 3 As shown, when the bedrock 100 is buried at a shallow depth, the bottom of the anti-seepage wall 10 extends into the bedrock 100 (i.e., extends into the soil-rock boundary 41 and enters the bedrock 100) and does not reach the permeability control layer 42 or the relatively impermeable rock layer 43, the top of the curtain grouting body 110 is connected to the bottom of the anti-seepage wall, the bottom of the curtain grouting body 110 extends into the permeability control layer 42 or the relatively impermeable rock layer 43, and the depth of the bottom of the curtain grouting body 110 extending into the permeability control layer 42 or the relatively impermeable rock layer 43 is not less than a first preset value. With this structural design, it is possible to ensure that the bottom of the curtain grouting body 110 is in full contact with the permeability control layer 42 or the relatively impermeable rock layer 43, and then fully utilize the anti-seepage characteristics of the permeability control layer 42 or the relatively impermeable rock layer 43 to ensure the anti-seepage effect of the curtain grouting body 110, thereby facilitating the overall anti-seepage effect of the anti-seepage wall 10 connected to the curtain grouting body 110.

[0043] As a possible implementation, see Figure 3As shown, the depth of the bottom of the anti-seepage wall 10 extending into the bedrock 100 is not less than the second preset value. The second preset value can be customized according to actual construction requirements. With this structural design, it is possible to ensure that the bottom of the anti-seepage wall 10 is in full contact with the bedrock 100, thereby facilitating the stability of the construction of the anti-seepage wall 10.

[0044] As a possible implementation, see Figure 3 As shown, the top of the curtain grouting body 110 extends into the bottom of the cut-off wall 10, and the depth of the top of the curtain grouting body 110 extending into the bottom of the cut-off wall 10 is not less than the third preset value. The third preset value can be customized according to actual construction requirements. With this structural design, it is possible to ensure that the top of the curtain grouting body 110 is in full contact with the bottom of the cut-off wall 10, thereby ensuring the firmness of the connection between the curtain grouting body 110 and the cut-off wall 10 during the curtain grouting construction, thereby facilitating the stability of the curtain grouting construction of the curtain grouting body 110.

[0045] As a possible implementation, see Figure 3 As shown, an impermeable wall cap 60 can be set at the bottom of the impermeable wall and the impermeable wall cap 60 can be covered with high plastic soil 70 to form an impermeable structure of the earth-rock dam 50. A second grouting pipe for constructing a curtain grouting body (i.e., a curtain grouting body 110) is vertically set at the bottom of the impermeable wall 10 along the dam axis direction. The upper end of the second grouting pipe extends into the bottom of the impermeable wall 10 and the depth of the extension is not less than the third preset value. The lower end of the second grouting pipe is closed and extends into the permeability control layer 42 or the relatively impermeable rock layer 43. The depth of the lower end of the second grouting pipe extending into the permeability control layer 42 or the relatively impermeable rock layer 43 is not less than the first preset value. With this structural design, it can be ensured that the upper and lower ends of the second grouting pipe are fully in contact with the impermeable wall 10 and the permeability control layer 42 or the relatively impermeable rock layer 43, respectively, thereby ensuring the stability of the grouting construction of the curtain grouting body, thereby facilitating the anti-seepage effect of the curtain grouting body.

[0046] As a possible implementation, see Figure 2 and Figure 3 As shown, the ultra-deep overburden dam foundation anti-seepage system can also include a construction platform 80 and a safety flood-proof platform 90 located above it; the upper end of the grouting area 20 is at the same horizontal plane as the safety flood-proof platform 90; the construction of the anti-seepage wall 10 starts when the earth-rock dam 50 is filled to the construction platform 80; the construction of the grouting area 20 starts when the earth-rock dam 50 is filled to the safety flood-proof platform 90.

[0047] The structural design of setting up the construction platform 80 and the flood safety platform 90 as mentioned above can provide a reasonable opportunity for the construction of the anti-seepage wall 10 and the grouting area 20 respectively during the filling process of the earth-rock dam 50, and as long as the earth-rock dam 50 is filled above the flood safety platform during the dry season, the safety of the construction of the grouting area 20 can be guaranteed, thereby realizing the simultaneous filling of the earth-rock dam 50 and the construction of the grouting area 20, thereby effectively improving the overall efficiency and safety of the construction.

[0048] For ease of understanding, the composition and construction method of the above-mentioned ultra-deep overburden dam foundation anti-seepage system are described as follows by taking a specific application as an example.

[0049] In actual application, the corresponding ultra-deep overburden dam foundation anti-seepage system can be designed for the two different dam foundation structures: the ultra-deep overburden contains a relatively impermeable soil layer and the rock layer below the ultra-deep overburden is shallow. Specifically, for the dam foundation structure with an ultra-deep overburden containing a relatively impermeable soil layer, the ultra-deep overburden dam foundation anti-seepage system can be designed as follows: Figure 2 The suspended anti-seepage system composed of a concrete anti-seepage wall (or reinforced concrete anti-seepage wall) and a controllable paste grouting structure is shown in the figure. For the dam foundation structure with a shallow rock layer under the ultra-deep overburden, the above ultra-deep overburden dam foundation anti-seepage system can be designed as Figure 3 The vertical fully enclosed anti-seepage system shown is composed of a concrete anti-seepage wall (or reinforced concrete anti-seepage wall), a controllable slurry grouting structure and a curtain grouting structure.

[0050] When designing the above-mentioned ultra-deep cover layer dam foundation anti-seepage system, the dam foundation anti-seepage standard can adopt the permeability of bedrock after irrigation: 3~5Lu control for level 1 and 2 dams and high dams, 5~10Lu control or relatively impermeable layer control for level 3 and below dams.

[0051] See also Figure 2 As shown, when there is a relatively impermeable soil layer 40 at the dam foundation, the anti-seepage measure is a combination of a concrete anti-seepage wall (or a reinforced concrete anti-seepage wall) and a controllable grouting structure. Figure 2 The middle part of the super-deep cover layer dam foundation anti-seepage system is an anti-seepage wall 10. A row of controllable grouting structures are respectively arranged on the upstream and downstream sides of the anti-seepage wall 10 as a grouting area 20. The depth of the bottom of the anti-seepage wall 10 extending into the relatively impermeable layer is 5.0m.

[0052] See also Figure 3 As shown, when the dam foundation bedrock Lu line (i.e. the rock layer connected by the positions in the bedrock 100 whose permeability is the permeability value corresponding to the above-mentioned dam foundation anti-seepage standard) Figure 3 When the permeability control layer 42 in the rock layer or the relatively impermeable rock layer 43 is buried at a shallow depth, the anti-seepage measure is a combination of a concrete anti-seepage wall (or a reinforced concrete anti-seepage wall) with a controllable grouting structure and a curtain grouting structure. Figure 3The middle part of the super-deep overburden dam foundation anti-seepage system is an anti-seepage wall 10, and the bottom of the anti-seepage wall 10 is connected to a curtain grouting structure (i.e. Figure 3 In the embodiment of the present invention, a curtain grouting body 110 is constructed, and a row of controllable grouting structures are respectively arranged on the upstream and downstream sides of the anti-seepage wall 10 as the grouting area 20; the bottom of the anti-seepage wall has not reached the bedrock line or the relatively impermeable rock layer 43, and the curtain grouting structure is adopted after the bottom of the anti-seepage wall enters the rock layer (i.e., extends into the soil-rock boundary line 41) by 1.0m; the grouting pipes need to be pre-buried inside the anti-seepage wall in advance for the construction of the curtain grouting structure, and the hole spacing (i.e., the horizontal distance between two adjacent grouting holes) between the grouting pipes (i.e., the second grouting pipes) used for the construction of the curtain grouting structure is 1.5m, and the elevation of the bottom of the curtain grouting structure is controlled to be 5m below the bedrock line or the relatively impermeable rock layer 43. The number of rows of grouting pipes used in the curtain grouting structure can be determined according to the seepage analysis and the importance of the project. If the grouting pipes used in the curtain grouting structure are arranged in multiple rows, the grouting holes of the curtain grouting structure can be arranged in combination with the controllable grouting holes.

[0053] exist Figure 2 and Figure 3 In the ultra-deep overburden dam foundation anti-seepage system shown, a row of controllable grout grouting structures are respectively arranged along the dam axis on the upstream and downstream sides of the anti-seepage wall 10. The hole spacing (i.e., the horizontal distance between two adjacent grouting holes) between the grouting pipes (i.e., the first grouting pipes) used for constructing the controllable grout grouting structures is 1.5 m, and the spacing from the center line of the grouting holes to the center line of the anti-seepage wall 10 is 1.5 m. When the bottom of the anti-seepage wall 10 enters the relatively impermeable soil layer 40, the grouting depth of the controllable grout grouting structure is the same as the filling height of the anti-seepage wall. When the bottom of the anti-seepage wall 10 enters the rock layer, the depth of the controllable grout grouting structure entering the rock layer is not less than 5.0 m.

[0054] In addition, whether the anti-seepage wall 10 is equipped with steel bars and the number of steel bars required for the anti-seepage wall 10 can be calculated and determined based on the structure of the anti-seepage wall 10, and the thickness of the anti-seepage wall 10 can be calculated and determined based on the thickness of the ultra-deep covering layer 30 (for example, the thickness of the anti-seepage wall 10 is 0.6m, 0.8m, 1.0m, 1.2m, etc.).

[0055] The principles of the ultra-deep overburden dam foundation anti-seepage system provided by the present invention mainly include the following aspects:

[0056] (1) In high-seismic areas, during earthquake conditions, the cut-off wall and the soil often break due to excessive and uneven stress, which leads to seepage damage to the dam foundation. The ultra-deep cover layer dam foundation anti-seepage system provided by the present invention adopts one row of controllable slurry grouting structures upstream and downstream of the cut-off wall. The elastic modulus of the controllable slurry used in the controllable slurry grouting structure is between that of concrete and soil, thereby achieving a buffering effect. On the one hand, it reduces the deformation of the cut-off wall and the tensile stress it receives. On the other hand, it avoids the hollowing phenomenon between the cut-off wall and the soil due to the earthquake, thereby avoiding the cut-off wall from being damaged by seepage due to the reduction or even failure of its foundation anti-seepage effect.

[0057] (2) Aiming at the problem in the prior art that the anti-seepage wall of the ultra-deep overburden layer dam foundation is often damaged by seepage due to construction defects, and the anti-seepage effect of the anti-seepage wall of the ultra-deep overburden layer dam foundation is poor due to the difficulty in constructing the anti-seepage wall of the ultra-deep overburden layer dam foundation and the difficulty in ensuring the construction quality, the ultra-deep overburden layer dam foundation anti-seepage system provided by the present invention forms flexible auxiliary anti-seepage structures on the anti-seepage wall and downstream respectively, thereby effectively supplementing the overall anti-seepage effect of the dam foundation when the anti-seepage effect of the anti-seepage wall is poor.

[0058] (3) In view of the problem that it is difficult to achieve anti-seepage of the ultra-deep overburden layer of the dam in the prior art, the ultra-deep overburden layer dam foundation anti-seepage system provided by the present invention proposes two anti-seepage solutions: ultra-deep anti-seepage wall + ultra-deep controllable slurry grouting and ultra-deep anti-seepage wall + ultra-deep controllable slurry grouting + ultra-deep curtain grouting, which can effectively solve the problem of anti-seepage of the ultra-deep overburden layer dam foundation.

[0059] The construction methods of the ultra-deep overburden dam foundation anti-seepage system provided by the present invention are mainly the following two:

[0060] (I) Construction plan of suspended ultra-deep anti-seepage system. The specific construction steps mainly include:

[0061] Step 1.1: After the dam is filled to the construction platform, the concrete cut-off wall (or reinforced concrete cut-off wall) is constructed.

[0062] Step 1.2: The bottom of the concrete cut-off wall (or reinforced concrete cut-off wall) is constructed to 5m below the relatively impermeable soil layer, and the top cap of the cut-off wall is 5m higher than the construction platform.

[0063] Step 1.3: After the dam is filled to the safe flood-proof platform, a controllable slurry grouting structure is constructed upstream and downstream of the concrete cut-off wall (or reinforced concrete cut-off wall) along the axial direction. The spacing between grouting holes is 1.5m, and the grouting depth is 5m below the bottom of the concrete cut-off wall (or reinforced concrete cut-off wall). The top of the controllable slurry grouting structure is at the elevation of the construction platform.

[0064] Step 1.4: The controllable paste grouting structure is constructed in stages, which is divided into 3 stages. The construction sequence of the grouting holes is as follows: Figure 4 shown.

[0065] Figure 4 In the construction of the controllable slurry grouting structure, it is necessary to set up a row of grouting pipes 201 for the construction of the controllable slurry grouting structure on the upstream and downstream sides of the anti-seepage wall 10 along the dam axis. The hole spacing between each row of grouting pipes 201 is 1.5m, and the spacing from the center line of the grouting hole to the center line of the anti-seepage wall 10 is 1.5m. The grouting holes corresponding to the grouting pipes 201 required for the construction of the controllable slurry grouting structure in the first, second and third phases are respectively recorded as sequence holes, II sequence holes, and III sequence holes.

[0066] (II) Construction plan for vertical fully enclosed anti-seepage system. The specific construction steps mainly include:

[0067] Step 2.1: After the dam is filled to the construction platform, the concrete cut-off wall (or reinforced concrete cut-off wall) is constructed.

[0068] Step 2.2: The bottom of the concrete anti-seepage wall (or reinforced concrete anti-seepage wall) should be no less than 1m into the soil-rock boundary line, and the top cap of the anti-seepage wall should be 5m higher than the construction platform.

[0069] Step 2.3: During the construction of the anti-seepage wall, grouting pipes for the construction of curtain grouting structure are reserved at intervals of 1.5m along the center line. The construction of the curtain grouting structure must be carried out after the concrete anti-seepage wall (or reinforced concrete anti-seepage wall) has a curing age of 28 days.

[0070] Step 2.4: After the concrete cut-off wall (or reinforced concrete cut-off wall) has been cured for 28 days, the lower curtain grouting structure is constructed. The bottom elevation of the curtain grouting structure is 5m below the bedrock Lu line or relatively impermeable rock layer. The curtain grouting structure is constructed in stages, divided into 3 stages, see Figure 5 .

[0071] Figure 5 In the construction of the curtain grouting structure, a row of grouting pipes 111 need to be pre-buried inside the anti-seepage wall 10, and the hole spacing between the grouting pipes 111 is 1.5m. The grouting holes corresponding to the grouting pipes 111 required for the first, second and third phases of the curtain grouting structure construction are recorded as sequence holes, II sequence holes and III sequence holes respectively.

[0072] Step 2.5: The pressure grouting of the curtain grouting structure is lifted to 2.0m above the bottom of the anti-seepage wall and then terminated. After the grouting is completed, the anti-seepage wall is sealed.

[0073] Step 2.6, after the dam is filled to the safe flood platform, the controllable grouting structure is constructed upstream and downstream of the concrete anti-seepage wall (or reinforced concrete anti-seepage wall) along the axial direction. The spacing between grouting holes is 1.5m, and the grouting depth of the controllable grouting structure is 5m below the lower limit of the soil-rock boundary (i.e. 4.0m below the bottom of the anti-seepage wall). The top of the controllable grouting structure is at the elevation of the construction platform.

[0074] Step 2.7: The controllable paste structure is constructed in stages, which is divided into 3 stages. The construction sequence of the grouting holes is as follows: Figure 4 shown.

[0075] When the bedrock is broken and multiple rows of grouting pipes need to be arranged for the construction of curtain grouting structure, the curtain grouting structure can be constructed synchronously with the controllable paste grouting structure in sequence.

[0076] In addition, when constructing the super-deep overburden dam foundation anti-seepage system, 1 to 3 rows of grouting pipes can be laid on the upstream and downstream sides of the anti-seepage wall according to the conditions of the super-deep overburden to facilitate the construction of the controllable paste grouting structure. The grouting pipes used for the construction of the controllable paste grouting structure and the grouting pipes used for the construction of the curtain grouting structure can be adjusted to 1.5m, 2.0m, 2.5m, 3.0m, etc. according to the geological conditions, and the hole spacing of the grouting pipes is not limited here.

[0077] In order to verify the beneficial effects of the ultra-deep cover layer dam foundation anti-seepage system provided by the present invention, three-dimensional finite element calculations can be performed through actual cases, so as to compare the strain and stress response results of the concrete anti-seepage wall in the anti-seepage schemes with and without the controllable grouting structure of the dam foundation ultra-deep cover layer under the action of strong earthquakes, so as to illustrate that the controllable grouting structure can form a transition layer between the concrete anti-seepage wall and the soil, so that under strong earthquakes, the force transition of the ultra-deep cover layer dam foundation anti-seepage system provided by the present invention can be uniform, and the seepage damage of the dam foundation caused by the destruction of the ultra-deep cover layer dam foundation anti-seepage system can be effectively avoided.

[0078] Figure 6 The overall model of the dam for three-dimensional finite element calculations is shown. Figure 7 The examples show the models of dam shell, clay core wall, concrete cut-off wall and controllable grouting structure for 3D finite element calculation. Based on the constructed models, 3D finite element calculation can be performed and the results can be analyzed in the following ways:

[0079] 1) According to the anti-seepage scheme of setting controllable paste grouting structure, the stress and strain response of the concrete anti-seepage wall is studied, and the displacement cloud diagram of the strain response and the stress distribution diagram of the stress response are obtained.

[0080] Figures 8 to 9 The displacement cloud diagrams of the X- and Z-direction seismic strain responses of the concrete anti-seepage wall in the anti-seepage scheme with a controllable grouting structure are shown respectively. Figures 10 to 12 The stress distribution diagrams of the seismic stress response of the concrete anti-seepage wall in the anti-seepage scheme with a controllable grouting structure are shown respectively.

[0081] 2) For the anti-seepage scheme without controllable paste grouting structure, the stress and strain response of the concrete anti-seepage wall is studied to obtain the displacement cloud diagram of the strain response and the stress distribution diagram of the stress response.

[0082] Figure 13 to Figure 14 The displacement cloud diagrams of the X- and Z-direction seismic strain responses of the concrete anti-seepage wall in the anti-seepage scheme without the controllable grouting structure are shown respectively. Figures 15 to 17 The stress distribution diagrams of the seismic stress response of the concrete anti-seepage wall in the X, Y and Z directions in the anti-seepage scheme without the controllable grouting structure are shown respectively.

[0083] 3) Comparison of results.

[0084] The displacement cloud diagrams of the same-direction seismic strain response of the concrete cut-off wall in the anti-seepage schemes with and without the controllable grout grouting structure can be compared respectively, and the stress distribution diagrams of the same-direction seismic stress response of the concrete cut-off wall in the anti-seepage schemes with and without the controllable grout grouting structure can be compared respectively, and the results comparison shown in Table 1 can be obtained.

[0085] Table 1 Comparison of the results of the anti-seepage scheme with and without controllable paste grouting structure

[0086]

[0087] According to the comparison of the results, the maximum stress of the concrete anti-seepage wall is significantly reduced when the controllable slurry structure is set up compared with the case without the controllable slurry structure, and the overall stress of the concrete anti-seepage wall is reduced.

[0088] In summary, the ultra-deep overburden dam foundation anti-seepage system provided by the present invention has the following advantages:

[0089] Two anti-seepage schemes are provided for the foundation of earth-rock dam in the ultra-deep overburden in strong earthquake zones: anti-seepage wall + controllable grouting and anti-seepage wall + controllable grouting structure + curtain grouting anti-seepage structure. The controllable grouting structure arranged on the upper and downstream sides of the anti-seepage wall can form a transition layer between the anti-seepage wall and the soil. In strong earthquake zones, this transition layer can make the force transition of the anti-seepage system of the ultra-deep overburden dam foundation uniform, effectively avoiding the seepage damage of the dam foundation caused by the damage of the anti-seepage system of the ultra-deep overburden dam foundation; when cracks or defects appear in the anti-seepage wall due to construction or earthquake, the controllable grouting structure can effectively form an anti-seepage effect supplement, thereby avoiding seepage damage to the dam foundation; it can achieve basic anti-seepage for earth-rock dams on ultra-deep cover layers (cover layer depth>100m); since the controllable grouting structure construction and the dam continued filling can be carried out simultaneously after the dam is filled to the safe flood platform, the construction progress can be effectively improved, thereby reducing the construction safety risk; due to the existence of the controllable grouting structure as a transition layer, the overall stress of the anti-seepage wall is smaller and the stress distribution is more uniform. Only a small amount of steel bars are needed to meet the construction requirements of the anti-seepage wall, which can effectively reduce the amount of reinforcement of the anti-seepage wall, and the anti-seepage wall has better economy when the anti-seepage effect is the same.

[0090] Based on the above-mentioned first ultra-deep overburden dam foundation anti-seepage system, the present invention further provides a construction method of the ultra-deep overburden dam foundation anti-seepage system, which can be used to construct the above-mentioned first ultra-deep overburden dam foundation anti-seepage system, and the construction method may include the following steps:

[0091] Step S101, constructing an anti-seepage wall and connecting the top of the anti-seepage wall to the anti-seepage structure of the earth-rock dam body.

[0092] Step S102, after the construction of the anti-seepage wall is completed, the grouting area is constructed, and after the construction of the grouting area is completed, an ultra-deep cover layer dam foundation anti-seepage system is obtained.

[0093] Based on the above second ultra-deep overburden dam foundation anti-seepage system, the present invention also provides another construction method of the ultra-deep overburden dam foundation anti-seepage system, which can be used to construct the above second ultra-deep overburden dam foundation anti-seepage system, and the construction method may include the following steps:

[0094] Step S111, constructing an anti-seepage wall and connecting the top of the anti-seepage wall to the anti-seepage structure of the earth-rock dam body.

[0095] Step S112, after the construction of the anti-seepage wall is completed, the curtain grouting body is constructed, and then the grouting area is constructed, and after the construction of the grouting area is completed, the ultra-deep cover layer dam foundation anti-seepage system is obtained.

[0096] The construction method of the ultra-deep overburden layer dam foundation anti-seepage system provided in the embodiment of the present invention has the same implementation principle and technical effects as those of the aforementioned ultra-deep overburden layer dam foundation anti-seepage system embodiment. For the sake of brief description, for matters not mentioned in the method embodiment, reference may be made to the corresponding contents in the aforementioned system embodiment.

[0097] Unless otherwise specifically stated, the relative steps, numerical expressions and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0098] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0099] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An ultra-deep overburden dam foundation anti-seepage system, characterized in that: The ultra-deep overburden dam foundation anti-seepage system is arranged in the ultra-deep overburden, and the ultra-deep overburden dam foundation anti-seepage system comprises an anti-seepage wall vertically arranged in the dam foundation along the dam axis direction and grouting areas respectively arranged on the upstream and downstream sides of the anti-seepage wall; the anti-seepage wall is perpendicular to the flow direction of the water flow, the grouting area is arranged along the axis direction of the anti-seepage wall, the upper end elevation of the grouting area is consistent with the top elevation of the anti-seepage wall, and the grouting area extends into the first target layer; the first target layer is a relatively impermeable soil layer in the ultra-deep overburden or a soil layer located below the ultra-deep overburden. bedrock; the elastic modulus of the slurry used for constructing the grouting area is between the elastic modulus of the cut-off wall and the elastic modulus of the dam foundation; the top of the cut-off wall is connected to the anti-seepage structure of the earth-rock dam body; the bottom of the cut-off wall extends into the first target layer; the bedrock is located below the ultra-deep covering layer, and the permeability coefficient of the relatively impermeable soil layer is less than the permeability coefficients of other soil layers in the ultra-deep covering layer that are adjacent to the relatively impermeable soil layer above and below; the anti-seepage structure of the dam body is formed by a high-plasticity soil-covered anti-seepage wall cap, and the anti-seepage wall cap is arranged on the top of the cut-off wall; The bottom of the anti-seepage wall is connected to a plugging body; the upstream side and the downstream side of the anti-seepage wall are each vertically provided with a first grouting pipe for constructing the grouting area along the dam axis direction, the upper end of the first grouting pipe is connected to the earth-rock dam, and the lower end of the first grouting pipe is connected to the plugging body; the top of the plugging body is connected to the bottom of the anti-seepage wall, and the vertical distance between the bottom of the plugging body and the bottom of the anti-seepage wall is not less than a fourth preset value; The ultra-deep overburden dam foundation anti-seepage system also includes a construction platform and a safety flood-proof platform located above it; the construction of the anti-seepage wall begins when the earth-rock dam is filled to the construction platform; the upper end of the grouting area is at the same horizontal plane as the safety flood-proof platform, and the construction of the grouting area begins when the earth-rock dam is filled to the safety flood-proof platform.

2. An ultra-deep overburden dam foundation anti-seepage system, characterized in that: The ultra-deep overburden dam foundation anti-seepage system is arranged in the ultra-deep overburden, and the ultra-deep overburden dam foundation anti-seepage system comprises an anti-seepage wall vertically arranged in the dam foundation along the dam axis direction and grouting areas respectively arranged on the upstream and downstream sides of the anti-seepage wall; the anti-seepage wall is perpendicular to the flow direction of the water flow, the grouting area is arranged along the axis direction of the anti-seepage wall, the elevation of the upper end of the grouting area is consistent with the elevation of the top of the anti-seepage wall, and the grouting area extends into the bedrock below the ultra-deep overburden; the elastic modulus of the slurry used to construct the grouting area is between the elastic modulus of the anti-seepage wall and the elastic modulus of the dam foundation; the top of the anti-seepage wall is connected to the anti-seepage structure of the earth-rock dam body; the bottom of the anti-seepage wall is connected with a curtain grouting body, The bottom of the curtain grouting body extends into the second target layer; the second target layer is a permeability control layer or a relatively impermeable rock layer in the bedrock; the permeability of the permeability control layer is a preset permeability value corresponding to the dam foundation anti-seepage standard, and the permeability coefficient of the relatively impermeable rock layer is less than the permeability coefficient of other rock layers in the bedrock that are adjacent to the relatively impermeable rock layer above and below; the bottom of the anti-seepage wall extends into the bedrock and does not reach the second target layer, the top of the curtain grouting body is connected to the bottom of the anti-seepage wall, and the depth of the bottom of the curtain grouting body extending into the second target layer is not less than a first preset value; the anti-seepage structure of the dam body is formed by an anti-seepage wall cap covered with high plasticity soil, and the anti-seepage wall cap is arranged on the top of the anti-seepage wall; A second grouting pipe for constructing the curtain grouting body is vertically arranged at the bottom of the cut-off wall along the dam axis direction, the upper end of the second grouting pipe extends into the bottom of the cut-off wall, the depth of the upper end of the second grouting pipe extending into the bottom of the cut-off wall is not less than a third preset value, the lower end of the second grouting pipe is closed and extends into the second target layer, the depth of the lower end of the second grouting pipe extending into the second target layer is not less than the first preset value; The ultra-deep overburden dam foundation anti-seepage system also includes a construction platform and a safety flood-proof platform located above it; the construction of the anti-seepage wall begins when the earth-rock dam is filled to the construction platform; the upper end of the grouting area is at the same horizontal plane as the safety flood-proof platform, and the construction of the grouting area begins when the earth-rock dam is filled to the safety flood-proof platform.

3. The ultra-deep overburden dam foundation anti-seepage system according to claim 2, characterized in that: The bottom of the cut-off wall extends into the bedrock to a depth not less than a second preset value; the top of the curtain grouting body extends into the bottom of the cut-off wall, and the top of the curtain grouting body extends into the bottom of the cut-off wall to a depth not less than a third preset value.

4. A construction method for an ultra-deep overburden dam foundation anti-seepage system, characterized in that: The construction method is used to construct the ultra-deep overburden dam foundation anti-seepage system according to claim 1, and the construction method comprises: Carrying out the construction of the anti-seepage wall, and connecting the top of the anti-seepage wall with the anti-seepage structure of the earth-rock dam body; The construction of the grouting area is carried out after the construction of the anti-seepage wall is completed, and the ultra-deep covering layer dam foundation anti-seepage system is obtained after the construction of the grouting area is completed.

5. A construction method for an ultra-deep overburden dam foundation anti-seepage system, characterized in that: The construction method is used to construct the ultra-deep overburden dam foundation anti-seepage system according to claim 2 or 3, and the construction method comprises: Carrying out the construction of the anti-seepage wall, and connecting the top of the anti-seepage wall with the anti-seepage structure of the earth-rock dam body; After the construction of the anti-seepage wall is completed, the curtain grouting body is constructed, and then the grouting area is constructed. After the construction of the grouting area is completed, the ultra-deep covering layer dam foundation anti-seepage system is obtained.

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