A method for strengthening the dam body of an asphalt core wall dam located on a deep overburden layer

Abstract

The present invention discloses a method for reinforcing an asphalt core dam located on a deep covering layer. The method comprises the following steps: excavating the surface of the covering layer to the bottom elevation of a concrete pedestal to form a steel-plastic bidirectional geogrid laying area; an intersection area exists between the steel-plastic bidirectional geogrid laying area and the concrete pedestal foundation pit; pouring pedestal concrete and forming the area integrally with the steel-plastic bidirectional geogrid located in the pedestal; continuously laying the steel-plastic bidirectional geogrid upward layer by layer on the top surface of the pedestal and simultaneously constructing the asphalt concrete core wall until the dam body construction is completed; the present invention adopts the steel-plastic bidirectional geogrid to connect the concrete anti-seepage wall, the pedestal and the deep covering layer in the deep covering layer into a whole, which can significantly improve the ability of the overall anti-seepage system composed of the asphalt core wall, the pedestal and the anti-seepage wall to resist the uncoordinated deformation caused by large deformation of the deep covering layer caused by dam body filling, water storage and seismic loads, and can improve the deep anti-sliding stability of the asphalt core dam located on a deep covering layer with a weak interlayer.

Description

Technical Field

[0001] The present invention relates to the technical field of dam body construction, in particular to a method for reinforcing an asphalt core dam body located on a thick covering layer. Background Art

[0002] To date, my country has made considerable progress in utilizing overburden for dam construction, with various dam types constructed on overburden, including clay core rockfill dams, asphalt concrete core rockfill dams, concrete face rockfill dams, concrete gravity dams, and arch dams. However, due to the unique topography and geological environment of western China, most mainstream rivers in this region face a unique geological challenge: a deep overburden layer on the riverbed, ranging in depth from several hundred meters to over 50 meters. Constructing high earth-rockfill dams on such deep overburden presents significant engineering challenges, such as inconsistent deformation of the impermeable structure caused by the deep overburden and deep-seated anti-sliding stability caused by earthquakes. Therefore, the economical and effective reinforcement of this deep overburden layer at the dam foundation remains an ongoing research endeavor.

[0003] To address the deep-layer anti-sliding issues and the uncoordinated deformation of the dam body and foundation when building high earth-rockfill dams on thick overburden, current designs for deep overburden dam foundation reinforcement primarily involve removing the entire overburden soil from the dam body area, reinforcing it with vibro-replacement crushed stone piles, consolidating the dam foundation with grouting, and arranging weights upstream and downstream. These methods, however, are both prohibitively expensive and lack the rationality of evaluating the effectiveness of reinforcement when the overburden is over 100 meters deep and contains deep, weak interlayers.

[0004] For example, CN 112195910A discloses a structure and construction method for treating soft foundations of earth-rock dams using vibro-reinforced gravel piles and rockfill. The method involves installing a group of vibro-reinforced gravel piles in a soft overburden layer to reinforce the deep, soft foundation of the dam. The bottoms of the gravel piles are located above the dense layer of the overburden layer or weathered bedrock. The earth-rock dam's anti-seepage system consists of an overburden foundation anti-seepage wall and a dam body anti-seepage body. A foundation filter pad is arranged on top of the gravel piles on the downstream side of the anti-seepage wall. A reinforced rockfill area is constructed above the gravel piles on the upstream side of the anti-seepage wall and above the foundation filter pad on the downstream side. This prior art utilizes a pile foundation reinforcement method to reinforce the soft overburden layer, but pile foundation construction is not only time-consuming but also expensive.

[0005] In order to solve the above problems, the present invention provides a method for reinforcing an asphalt core dam located on a deep covering layer, so as to solve the problems of high construction cost of the covering layer dam body and deep anti-sliding stability of the upper structure due to the presence of a weak interlayer inside the covering layer. Summary of the invention

[0006] The object of the present invention is to provide a method for reinforcing the dam body of an asphalt core wall dam located on a deep overburden layer, achieving the purpose of improving the bearing capacity of the dam foundation and the deep anti-sliding stability of the dam body at low construction cost and technical difficulty.

[0007] To achieve the above object, the present invention provides the following solution:

[0008] A method for reinforcing the dam body of an asphalt core wall dam located on a deep overburden layer, comprising the following steps:

[0009] Determine the top elevation of the cutoff wall, excavate the surface layer of the overburden layer to form a laying area for a steel-plastic biaxial geogrid, complete the hole formation and construction of the cutoff wall. There is an intersection area between the laying area of the steel-plastic biaxial geogrid and the foundation pit of the concrete cushion. The intersection area is above the top elevation of the cutoff wall. In the intersection area, lay the steel-plastic biaxial geogrid layer by layer from bottom to top and extend it into the concrete cushion area located in the intersection area. Pour the concrete cushion to the top elevation and integrally form it with the steel-plastic biaxial geogrid located in the cushion;

[0010] Continue to lay the steel-plastic biaxial geogrid along the intersection area to the upstream and downstream dam toes of the dam body, complete the backfill of the dam shell material and integrally form it with the steel-plastic biaxial geogrid located in the cushion, constituting a steel-plastic biaxial geogrid reinforced composite foundation at the bottom of the dam body;

[0011] On the top surface of the cushion, continue to lay the steel-plastic biaxial geogrid layer by layer to the design height and simultaneously construct the asphalt concrete core wall. The steel-plastic biaxial geogrid does not cross the asphalt concrete core wall;

[0012] When laying each layer of the steel-plastic biaxial geogrid, extend it to the upstream and downstream dam toes on both sides;

[0013] Construct the rockfill areas on both sides of the asphalt concrete core wall until the dam body construction is completed.

[0014] Preferably, the height of the steel-plastic biaxial geogrid constructed simultaneously with the asphalt concrete core wall is one-fifth to one-fourth of the dam height.

[0015] Preferably, dry rubble slopes are provided on both the upstream and downstream faces of the dam body.

[0016] Preferably, after the cushion concrete construction is completed, lay a composite geomembrane along the direction perpendicular to the cushion trend and extend it onto the cushion.

[0017] Preferably, a filter layer is constructed on the composite geomembrane.

[0018] Preferably, asphalt mastic and water-stop copper sheets are provided at the connection between the asphalt concrete core wall and the cushion.

[0019] Preferably, the excavation depth of the covering layer is 2 meters to 5 meters.

[0020] Preferably, the spacing between adjacent steel-plastic bidirectional geogrids in the covering layer is 1.0 meter, and the spacing between the steel-plastic bidirectional geogrids laid inside the dam body is 2.0 to 3.0 meters.

[0021] Preferably, the steel-plastic bidirectional geogrid has an ultimate elongation greater than 3%, an ultimate tensile strength greater than 80 kN / m, and a transverse and longitudinal node peeling force greater than 300 N.

[0022] Preferably, a grouting and inspection gallery is provided inside the pad along the direction of the anti-seepage wall.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] 1. The present invention uses a steel-plastic bidirectional geogrid to connect the concrete cut-off wall, pad and deep covering layer located in the deep covering layer into a whole, and performs wrap-type reinforcement on the upper and lower downstream sides of the asphalt concrete core wall, which significantly improves the ability of the overall anti-seepage system composed of the asphalt core wall-pad-cut-off wall to resist the uncoordinated deformation caused by large deformation of the deep covering layer caused by dam filling, water storage and seismic loads, and can greatly improve the deep anti-sliding stability of the asphalt core wall dam located on a deep covering layer with a weak interlayer; in addition, the construction process of the present invention is simple and consumes less materials, which not only speeds up the construction progress but also reduces the construction cost.

[0025] 2. In the present invention, each layer of steel-plastic bidirectional geogrid extends to both sides to the upstream dam foot and the downstream dam foot when laid, forming a composite foundation to improve the bearing capacity of the asphalt core dam foundation located on a deep covering layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Attached Figure 1 It is a structural schematic diagram of the present invention;

[0028] Attached Figure 2 This is the enlarged view of point A;

[0029] Among them, 1. Anti-seepage wall; 2. Steel-plastic bidirectional geogrid; 3. Pad; 4. Grouting and inspection corridor; 5. Asphalt horseshoe grease; 6. Water-stop copper sheet; 7. Asphalt concrete core wall; 8. Dam body; 9. Composite geomembrane; 10. Covering layer. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] The object of the present invention is to provide a method for strengthening the dam body of an asphalt core wall dam located on a deep overburden layer, so as to achieve the purposes of improving the bearing capacity of the dam foundation, the deep anti-sliding stability of the dam body, and reducing the construction cost.

[0032] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Reference Figures 1 to 2, a method for reinforcing the body of an asphalt core dam located on a deep covering layer, determining the top surface elevation of the anti-seepage wall 1, excavating the surface of the covering layer 10 to the top elevation of the anti-seepage wall 1 and forming a steel-plastic bidirectional geogrid paving area 2, completing the construction of the concrete anti-seepage wall 1, and completing the construction of the concrete anti-seepage wall 1. There is an intersection area between the steel-plastic bidirectional geogrid 2 paving area and the concrete pad 3 foundation pit, and the intersection area is located above the top surface elevation of the anti-seepage wall 1. The steel-plastic bidirectional geogrid 2 is laid layer by layer from bottom to top in the intersection area and extends into the concrete pad 3 area located in the intersection area, pouring the concrete pad 3 to the top surface elevation and forming it as one piece with the steel-plastic bidirectional geogrid 2 located in the pad 3; continuing to lay the steel-plastic bidirectional geogrid 2 along the intersection area to the upstream and downstream dam foot ranges of the dam body 8, completing the dam shell material backfill and forming it as one piece with the steel-plastic bidirectional geogrid 2 located in the pad 3, forming a steel-plastic bidirectional geogrid 2 reinforced composite foundation at the bottom of the dam body 8. Continue to lay the steel-plastic bidirectional geogrid 2 upward layer by layer on the top surface of the pad 3 to the designed height and simultaneously construct the asphalt concrete core wall 7. The steel-plastic bidirectional geogrid 2 and the asphalt concrete core wall 7 do not intersect; when laying each layer of the steel-plastic bidirectional geogrid 2, it extends along the upstream and downstream directions of the dam body 8 to the upstream dam foot and the downstream dam foot; construct rockfill areas on both sides of the asphalt concrete core wall 7 to form the steel-plastic bidirectional geogrid 2 composite dam body 8 until the dam body construction is completed, and construct rockfill areas on both sides of the asphalt concrete core wall 7 until the dam body construction is completed. The use of a steel-plastic bidirectional geogrid 2 connects the concrete cutoff wall 1, pad 3, and deep cover 10 within the deep cover 10 into a single unit. Wrap-around reinforcement is also provided on both the upstream and downstream sides of the asphalt concrete core wall 7. This significantly improves the ability of the integrated anti-seepage system, consisting of the asphalt core wall, pad 3, and cutoff wall 1, to resist the uncoordinated deformation of the deep cover 10 caused by large deformations during dam body 8 construction, water storage, and seismic loads. It also significantly enhances the deep-layer anti-sliding stability of asphalt core dams located on a deep cover 10 with a weak interlayer. Furthermore, the present invention features a simple construction process and consumes minimal materials, which not only accelerates construction progress but also reduces construction costs.

[0034] Furthermore, the height of the steel-plastic bidirectional geogrid 2 constructed simultaneously with the asphalt concrete core wall 7 is one-fifth to one-quarter of the dam body height; it is laid on both sides to the upstream and downstream dam slopes. On the premise of ensuring the overall anti-seepage effect of the asphalt concrete core wall 7, the geogrids on both sides reinforced the composite rockfill body to further reduce the hydraulic splitting damage caused by uneven deformation of the asphalt core wall.

[0035] Furthermore, dry stone slope protection is set on both the water-facing and water-retaining sides of the dam body to ensure the stability of the dam body slope.

[0036] Furthermore, after the concrete construction of the base 3 is completed, the composite geomembrane 9 is laid in a direction perpendicular to the direction of the base 3 and extends onto the base 3.

[0037] Furthermore, a filter layer is applied on the composite geomembrane 9 .

[0038] Furthermore, bituminous mastic 5 and water-stop copper sheet 6 are provided at the connection between the asphalt concrete core wall 7 and the cushion block 3.

[0039] Furthermore, the excavation depth of the overburden layer 10 is 2 meters to 5 meters.

[0040] Furthermore, the spacing between adjacent steel-plastic biaxial geogrids 2 within the overburden layer 10 is 1.0 meter, and the spacing between the steel-plastic biaxial geogrids 2 laid inside the dam body is 2.0 meters to 3.0 meters.

[0041] Furthermore, the steel-plastic biaxial geogrid 2 has an ultimate elongation greater than 3%, an ultimate tensile strength greater than 80 kN / m, and a transverse and longitudinal joint peeling force greater than 300 N.

[0042] Reference Figure 2 , a grouting and inspection gallery 4 is arranged inside the cushion block along the trend of the impervious wall.

[0043] Adaptations made according to actual requirements are all within the protection scope of the present invention.

[0044] It should be noted that for those skilled in the art, obviously the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. A method for reinforcing the dam body of an asphalt core wall dam located on a thick overburden layer, characterized in that, It includes the following contents: Determine the top elevation of the impervious wall, excavate the surface layer of the overburden to the top elevation of the impervious wall to form a steel-plastic biaxial geogrid laying area, complete the construction of the concrete impervious wall. There is an intersection area between the steel-plastic biaxial geogrid laying area and the concrete cushion foundation pit, and the intersection area is above the top elevation of the impervious wall. In the intersection area, lay the steel-plastic biaxial geogrid layer by layer from bottom to top and extend it into the concrete cushion area located in the intersection area, pour the concrete cushion to the top elevation and integrally form it with the steel-plastic biaxial geogrid located in the concrete cushion; Continue to lay the steel-plastic biaxial geogrid within the range from the intersection area to the upstream and downstream dam toes of the dam body, complete the backfilling of the dam shell material and integrally form it with the steel-plastic biaxial geogrid located in the concrete cushion to form a steel-plastic biaxial geogrid reinforced composite foundation at the bottom of the dam body; Continue to lay the steel-plastic biaxial geogrid layer by layer upward on the top surface of the concrete cushion to the design height and simultaneously construct the asphalt concrete core wall. The steel-plastic biaxial geogrid does not cross the asphalt concrete core wall; When laying each layer of the steel-plastic biaxial geogrid, it extends along the upstream and downstream directions of the dam body to the upstream dam toe and the downstream dam toe; Construct the rockfill areas on both sides of the asphalt concrete core wall to form a steel-plastic biaxial geogrid composite dam body until the construction of the dam body is completed.

2. A method for reinforcing the dam body of an asphalt core wall dam located on a thick overburden layer, characterized in that, The height of the steel-plastic biaxial geogrid constructed simultaneously with the asphalt concrete core wall is one-fifth to one-fourth of the dam height.

3. A method for strengthening the dam body of an asphalt core wall dam located on a deep overburden layer, characterized in that, Dry stone revetments are provided on both the upstream and downstream faces of the dam body.

4. A method for reinforcing the dam body of an asphalt core wall dam located on a deep overburden layer, characterized in that, After the concrete construction of the concrete cushion is completed, lay the composite geomembrane along the direction perpendicular to the trend of the concrete cushion and extend it onto the concrete cushion.

5. A method for reinforcing the dam body of an asphalt core wall dam located on a deep overburden layer, characterized in that, Construct an anti-filter layer on the composite geomembrane.

6. A method for reinforcing the dam body of an asphalt core wall dam located on a deep overburden layer, characterized in that, Asphalt mastic and water-stop copper sheets are provided at the connection between the asphalt concrete core wall and the concrete cushion.

7. A method for strengthening the dam body of an asphalt core wall dam located on a deep overburden layer, characterized in that, The excavation depth of the overburden is 2 meters to 5 meters.

8. A method for strengthening the dam body of an asphalt core wall dam located on a deep overburden layer, characterized in that, The spacing between the steel-plastic biaxial geogrids in the overburden excavation area is 1.0 meter, and the spacing between the steel-plastic biaxial geogrids inside the dam body is 2.0 meters to 3.0 meters.

9. A method for reinforcing the dam body of an asphalt core wall dam located on a thick overburden layer, characterized in that, The steel-plastic biaxial geogrid has an ultimate elongation greater than 3%, an ultimate tensile strength greater than 80 kN / m, and a transverse and longitudinal node peeling force greater than 300 N.

10. A method for reinforcing the dam body of an asphalt core wall dam located on a deep overburden layer, characterized in that, Grouting and inspection galleries are provided inside the concrete cushion along the trend of the impervious wall.

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