Layout structure and construction method of asphalt concrete core rockfill dam

Abstract

The present invention relates to an asphalt concrete core wall rockfill dam layout structure and construction method. The purpose of the present invention is to provide an asphalt concrete core wall rockfill dam layout structure and construction method, so as to improve the foundation adaptability of the asphalt concrete core wall rockfill dam, reduce the requirements for the performance of dam construction materials, and improve the safety and economy of the asphalt concrete core wall rockfill dam. The technical solution of the present invention is: an asphalt concrete core wall rockfill dam layout structure, characterized in that: the dam body of the asphalt concrete core wall rockfill dam adopts an arched layout convex to the upstream, and the dam axis of the dam body is formed by two arcs with radii R1 and R2 respectively, which are tangent to the middle of the riverbed; among the two arcs of the dam axis, the arc connected to the bank slope with steep slope and deep cover adopts a smaller arc radius, and the arc connected to the bank slope with relatively gentle slope and relatively shallow cover adopts a relatively larger arc radius; when the terrain and geological conditions on both sides of the bank are well symmetrical, the arc radius R1 is equal to R2.

Description

Technical Field

[0001] The present invention relates to an asphalt concrete core rockfill dam layout structure and construction method. It is suitable for asphalt concrete core rockfill dam projects where one or more of the aforementioned unfavorable factors, such as weak dam foundation soil, steep bank slopes, poor fill material quality, and large dam height and scale, lead to significant deformation of the dam body and foundation, resulting in high tensile stress in the asphalt concrete core walls on both sides of the dam, significant disturbance in the asphalt concrete core walls at the riverbed, and a high risk of core wall cracking. Background Art

[0002] Asphalt concrete cores, a flexible dam constructed with local materials, offer wide adaptability, reliable anti-seepage effectiveness, environmental friendliness, and low investment, making them widely used in various reservoir projects. For asphalt concrete core rockfill dams, the core's operational status is crucial to the safe operation of the entire dam. Current research and engineering experience indicate that the following unfavorable factors can affect the safe operation of a dam when the foundation soil is weak, the side slopes are steep, the fill material quality is poor, or the dam is large:

[0003] (1) During the dam filling process and operation, the dam body or dam foundation has large deformation, which will cause tensile stress and deformation in the core wall on both sides. Especially when the terrain on both sides is steep, the distribution range and magnitude of the tensile stress will be further aggravated;

[0004] (2) After impoundment, the core wall will experience large disturbance deformation due to the water thrust, especially in the riverbed where the dam height and water head are large, and the disturbance deformation is also the largest. When the tensile stress on the upstream surface caused by the disturbance deformation is too large, it will also cause cracking of the anti-seepage body;

[0005] (3) When the anti-seepage performance of the dam foundation soil is good, excess pore water pressure will appear during the filling process, affecting the settlement during the filling process and increasing the post-construction settlement;

[0006] (4) When the anti-seepage performance of the soil of the dam foundation is good, due to the anti-seepage effect of the soil, a hydraulic gradient will be generated in the soil during water storage and the initial operation. The water head on the surface of the soil layer is higher than the water head of the underlying soil. The additional stress caused by the water head difference further compresses the soil and increases the foundation settlement deformation of the upstream part of the anti-seepage body, especially when the water storage rate is fast.

[0007] When the tensile stress and disturbance deformation on both sides caused by the above factors exceed the ultimate tensile capacity of the asphalt concrete core wall material, cracks will appear and continue to intensify under the action of hydraulic fracturing, resulting in failure of the dam's anti-seepage and endangering the safety of the dam.

[0008] Currently, the main approach to addressing this issue is through strict control of dam body and foundation deformation, and measures such as improving the tensile properties of the asphalt concrete core wall. This approach primarily relies on improving material performance, but its effectiveness is limited by the material's inherent properties, and the investment is generally large. This is especially true when the foundation is composed of deep, soft soil layers, where the investment in treating the soft foundation increases significantly, potentially preventing the project from being successfully implemented. Therefore, by leveraging the deformation characteristics of the dam body and foundation, an asphalt concrete core wall rockfill dam structure and construction method suitable for deep, soft soil foundations have been developed. This effectively improves the stress state of the anti-seepage core wall, is of great significance for reducing project investment and improving project operational reliability, and has broad application value. Summary of the Invention

[0009] The technical problem to be solved by the present invention is: in response to the above-mentioned problems, a layout structure and construction method of an asphalt concrete core wall rockfill dam are provided to improve the foundation adaptability of the asphalt concrete core wall rockfill dam, reduce the requirements for the performance of dam construction materials, and improve the safety and economy of the asphalt concrete core wall rockfill dam.

[0010] The technical solution adopted by the present invention is: an asphalt concrete core wall rockfill dam layout structure, characterized in that: the asphalt concrete core wall rockfill dam body adopts an arched layout convex to the upstream, and the dam axis of the dam body is formed by two arcs with radii R1 and R2 respectively, which are tangent to each other in the middle of the riverbed;

[0011] Of the two arcs along the dam axis, the arc connected to the bank slope with a steeper slope and a deeper cover layer adopts a smaller arc radius, while the arc connected to the bank slope with a relatively gentle slope and a relatively shallow cover layer adopts a relatively larger arc radius; when the topographic and geological conditions on both sides of the bank are relatively symmetrical, the arc radius R1 is equal to R2.

[0012] The dam body and the dam crest are narrow at both banks and gradually widen toward the middle of the riverbed.

[0013] The downstream control line of the dam crest is composed of two arcs with radii R3 and R4 tangent to each other in the middle of the riverbed. The radii of the two arcs on the control line are larger than the radii of the corresponding arcs on the dam axis.

[0014] The asphalt concrete core wall in the dam body is arranged in the middle upstream position of the dam body.

[0015] The top thickness of the downstream main rockfill area downstream of the asphalt concrete core wall in the dam body changes accordingly with the change of the dam top width, and the top thickness of the downstream secondary rockfill area downstream of the downstream main rockfill area remains unchanged.

[0016] A filter layer and a transition layer are provided between the asphalt concrete core wall rockfill dam body and the underlying soil foundation.

[0017] The bottom of the asphalt concrete core wall in the asphalt concrete core rockfill dam body is connected to the foundation anti-seepage structure through a foundation gallery, and the top of the asphalt concrete core wall is connected to the wave-breaking wall.

[0018] A plurality of drainage facilities capable of shortening the drainage path of the soil foundation are arranged in the soil foundation below the dam body of the asphalt concrete core wall rockfill dam.

[0019] The drainage facilities adopt one or more of sand wells, vibro-stone piles and sand and gravel piles.

[0020] A construction method for the asphalt concrete core wall rockfill dam arrangement structure is characterized by:

[0021] During the construction of the asphalt concrete core wall rockfill dam, the dam body is divided into four filling layers along the elevation direction, which are, from bottom to top, the core wall foundation pit filling layer area I, the middle and lower dam body filling layer area II, the middle and upper dam body filling layer area III, and the top dam body filling layer area IV;

[0022] The middle and lower dam body filling layer area II is divided from upstream to downstream into the middle and lower upstream preliminary filling area II-1, the middle and lower core wall filling area II-3 and the middle and lower downstream preliminary filling area II-2; the middle and upper dam body filling layer area III is divided from upstream to downstream into the middle and upper upstream preliminary filling area III-1, the middle and upper core wall filling area III-3 and the middle and upper downstream preliminary filling area III-2;

[0023] The construction method comprises the following steps:

[0024] Determine the main parameters of the dam material zoning design and the dam axis on both sides;

[0025] Excavation of the dam foundation riverbed, including asphalt concrete core wall foundation and rockfill area foundation;

[0026] Carry out foundation treatment of core wall corridor, construct anti-seepage wall, and pour foundation corridor;

[0027] Construction of drainage facilities on earth foundations;

[0028] The dam body and core wall to the rockfill foundation surface in the core pit filling layer area I shall be constructed in accordance with the rolling process parameters of the dam body filling materials in the core pit filling layer area I and the asphalt concrete construction process requirements;

[0029] During construction, the upper and lower middle parts of the dam body filling layer II will be filled in Area II-1 and II-2 upstream and downstream to the designed filling top elevation;

[0030] The middle and lower core wall filling area II-3 of the middle and lower dam body filling layer area II during construction, to the designed filling top elevation;

[0031] Construct the middle and upper dam body filling layer area III according to the construction sequence of the middle and lower dam body filling layer area II;

[0032] Construction top dam filling layer zone IV;

[0033] Construct wave-breaking walls and ensure that the seepage control requirements between the wave-breaking walls and the asphalt concrete core wall are met;

[0034] Construct dam top transition material and dam top pavement structure layer;

[0035] The foundation curtain grouting construction is carried out through the foundation corridor.

[0036] The beneficial effect of this invention is that, unlike traditional linear dams, where the core wall bulges downstream to the left and right of the water thrust, the entire core wall is in a state of tension, exacerbating internal tensile stress. This invention utilizes an arched core wall structure that bulges upstream, converting water pressure into axially distributed compressive stress, fundamentally changing the stress state within the core wall.

[0037] The present invention utilizes the front arrangement of the core wall and the unequal width dam crest structure, and uses limited engineering resources to increase the thickness of the resistance body downstream of the core wall, while making the entire dam more scenic.

[0038] The present invention utilizes engineering waste to fill the upstream and downstream pressure slope bodies, which can not only dispose of the waste, but also improve the overall stability of the dam. Under the same safety conditions, this method can effectively reduce the scale of the dam body.

[0039] The present invention utilizes foundation treatment measures with drainage capabilities such as manholes, vibro-compaction gravel piles, and sand and gravel piles. While strengthening the foundation, it can effectively shorten the foundation drainage and consolidation time, accelerate foundation settlement, and reduce the adverse effects of post-construction settlement on the mood during operation.

[0040] The present invention utilizes a zoning filling scheme to reduce the adverse effects of settlement during dam filling on the core wall, and further improve the stress state of the core wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is the plan layout diagram of the dam body in the embodiment.

[0042] Figure 2 It is a typical structural diagram of the dam body in the embodiment.

[0043] Figure 3 This is a diagram of the filling divisions of the dam body in the embodiment.

[0044] In the figure: 1. Reservoir bank; 2. Asphalt concrete core wall rockfill dam body; 3. Soil foundation; 4. Asphalt concrete core wall; 5. Upstream weighted area; 6. Upstream rockfill area; 7. Upstream transition area; 8. Downstream transition area; 9. Downstream main rockfill area; 10. Downstream secondary rockfill area; 11. Downstream weighted area; 12. Filter layer; 13. Transition layer; 14. Foundation corridor; 15. Foundation anti-seepage structure; 16. Wave-breaking wall; 17. Dam top pavement structure layer; 18. Manhole. DETAILED DESCRIPTION

[0045] This embodiment is an asphalt concrete core rockfill dam layout structure, the asphalt concrete core rockfill dam body is arranged across the river, and the two ends of the dam body are connected to the reservoir bank. The asphalt concrete core rockfill dam is arranged in an arch shape that convexly faces upstream.

[0046] In this example, the dam axis is formed by two arcs with radii R1 and R2, which are tangent to each other in the middle of the riverbed. When the topographic and geological conditions on both sides of the river are relatively symmetrical, the arc radius R1 is equal to R2, forming a single circle arrangement. When the topographic and geological conditions on both sides of the river are generally symmetrical, the arc connected to the bank slope with steep slope and deep cover layer adopts a smaller arc radius, and the arc connected to the bank slope with relatively gentle slope and relatively shallow cover layer adopts a relatively larger arc radius, forming a two-center circle arrangement.

[0047] In this example, the crest width Δ1 of the asphalt concrete core rockfill dam is set to a variable width, narrow at the banks and gradually widening toward the center of the riverbed. To achieve both the variable width and architectural aesthetics, a control line is used downstream of the dam crest, consisting of two arcs with radii R3 and R4, tangent to the center of the riverbed. The radius of the arc on the control line is larger than the radius of the dam axis at the corresponding location (this ensures both tangency at the riverbed and a greater crest width in the middle of the river than on the banks).

[0048] In this embodiment, the asphalt concrete core of the asphalt concrete core rockfill dam is located on a soil foundation, with the asphalt concrete core positioned in the middle, slightly upstream, portion of the dam body. From upstream to downstream, the dam body structure comprises the upstream weighted zone, upstream rockfill zone, upstream transition zone, asphalt concrete core, downstream transition zone, downstream primary rockfill zone, downstream secondary rockfill zone, and downstream weighted zone. These zones can be further subdivided based on the material source properties, hydraulic transition relationships between zones, and deformation coordination requirements.

[0049] In this example, the top thickness Δ2 of the downstream primary rockfill area downstream of the asphalt concrete core of an asphalt core rockfill dam changes with the dam crest width Δ1, while the top thickness of the downstream secondary rockfill area remains unchanged. By varying the dimensions of Δ1 and Δ2, the size of the primary force-resisting body downstream of the asphalt concrete core increases with increasing dam crest height.

[0050] In this embodiment, a filter layer and a transition layer are set between the asphalt core wall rockfill dam body and the soil foundation. The bottom of the core wall is connected to the foundation anti-seepage structure (waterproof wall and foundation curtain) through the foundation corridor, and the top is connected to the wave-breaking wall.

[0051] In this embodiment, manholes are installed within the earthen foundation beneath the dam body. During filling, they shorten the drainage path within the foundation, effectively accelerating its settlement. During impoundment, the manholes' water-guiding effect effectively reduces the hydraulic gradient caused by infiltration within the foundation, minimizing additional settlement in the upstream portion of the core wall after impoundment. Manholes can also be replaced with drainage-capable foundation treatments such as vibro-compacted gravel piles or gravel piles, or they can be used in conjunction with manholes.

[0052] The specific construction method of this embodiment is as follows:

[0053] During the construction of the asphalt concrete core rockfill dam, the dam body is divided into four filling layers along the elevation direction, from bottom to top: core wall foundation pit filling layer area I, middle and lower dam body filling layer area II, middle and upper dam body filling layer area III, and top dam body filling layer area IV;

[0054] The middle and lower dam body filling layer area II is divided from upstream to downstream into the middle and lower upstream preliminary filling area II-1, the middle and lower core wall filling area II-3 and the middle and lower downstream preliminary filling area II-2; the middle and upper dam body filling layer area III is divided from upstream to downstream into the middle and upper upstream preliminary filling area III-1, the middle and upper core wall filling area III-3 and the middle and upper downstream preliminary filling area III-2;

[0055] The construction method in this embodiment includes the following steps:

[0056] The dam material zoning design and the key parameters for the dam axis on both sides, namely the dam layout parameters R1, R2, R3, and R4, were determined based on the topographical and geological conditions on both sides, the dam height, and the properties of the fill material. To select the appropriate arc, three-dimensional numerical simulation was used to compare and analyze different layout options.

[0057] Excavation of the dam foundation riverbed, including asphalt concrete core wall foundation and rockfill area foundation;

[0058] Carry out foundation treatment of core wall corridor, construct anti-seepage wall, and pour foundation corridor;

[0059] Construction of drainage facilities on earth foundations;

[0060] The dam body and core wall to the rockfill foundation surface in the core pit filling layer area I shall be constructed in accordance with the rolling process parameters of the dam body filling materials in the core pit filling layer area I and the asphalt concrete construction process requirements;

[0061] During construction, the upper and lower middle parts of the dam body filling layer II will be filled in Area II-1 and II-2 upstream and downstream to the designed filling top elevation;

[0062] The middle and lower core wall filling area II-3 of the middle and lower dam body filling layer area II during construction, to the designed filling top elevation;

[0063] Construct the middle and upper dam body filling layer area III according to the construction sequence of the middle and lower dam body filling layer area II;

[0064] Construction top dam filling layer zone IV;

[0065] Construct wave-breaking walls and ensure that the seepage control requirements between the wave-breaking walls and the asphalt concrete core wall are met;

[0066] Construct dam top transition material and dam top pavement structure layer;

[0067] The foundation curtain grouting construction is carried out through the foundation corridor.

Claims

1. An asphalt concrete core rockfill dam layout structure, characterized by: The asphalt concrete core rockfill dam adopts an arched layout convex to the upstream, and the dam axis is formed by two arcs with radii R1 and R2 respectively, which are tangent to each other in the middle of the riverbed. When the topographic and geological conditions on both sides of the dam are generally symmetrical, the arc connecting the bank with a steep slope and a deep overburden layer adopts a smaller arc radius, while the arc connecting the bank with a relatively gentle slope and a relatively shallow overburden layer adopts a relatively larger arc radius. When the topographic and geological conditions on both sides of the dam are relatively symmetrical, the arc radius R1 is equal to R2. The dam crest is narrow on both sides and gradually widens toward the middle of the riverbed; The downstream control line of the dam crest is composed of two arcs with radii R3 and R4, which are tangent to each other in the middle of the riverbed. The radii of the two arcs on the control line are larger than the radii of the corresponding arcs on the dam axis. A filter layer and a transition layer are provided between the asphalt concrete core wall rockfill dam body and the underlying soil foundation.

2. The asphalt concrete core rockfill dam arrangement structure according to claim 1, characterized in that: The asphalt concrete core wall in the dam body is arranged in the middle upstream position of the dam body.

3. The asphalt concrete core rockfill dam arrangement structure according to claim 2, characterized in that: The top thickness of the downstream main rockfill area downstream of the asphalt concrete core wall in the dam body changes accordingly with the change of the dam top width, and the top thickness of the downstream secondary rockfill area downstream of the downstream main rockfill area remains unchanged.

4. The asphalt concrete core rockfill dam arrangement structure according to claim 1, characterized in that: The bottom of the asphalt concrete core wall in the asphalt concrete core rockfill dam body is connected to the foundation anti-seepage structure through a foundation gallery, and the top of the asphalt concrete core wall is connected to the wave-breaking wall.

5. The asphalt concrete core rockfill dam arrangement structure according to claim 1, characterized in that: A plurality of drainage facilities capable of shortening the drainage path of the soil foundation are arranged in the soil foundation below the dam body of the asphalt concrete core wall rockfill dam.

6. The asphalt concrete core rockfill dam arrangement structure according to claim 5, characterized in that: The drainage facilities adopt one or more of sand wells, vibro-stone piles and sand and gravel piles.

7. A construction method for the asphalt concrete core rockfill dam arrangement structure according to any one of claims 1 to 6, characterized in that: During the construction of the asphalt concrete core wall rockfill dam, the dam body is divided into four filling layers along the elevation direction, which are, from bottom to top, the core wall foundation pit filling layer area I, the middle and lower dam body filling layer area II, the middle and upper dam body filling layer area III, and the top dam body filling layer area IV; The middle and lower dam body filling layer area II is divided from upstream to downstream into the middle and lower upstream preliminary filling area II-1, the middle and lower core wall filling area II-3 and the middle and lower downstream preliminary filling area II-2; the middle and upper dam body filling layer area III is divided from upstream to downstream into the middle and upper upstream preliminary filling area III-1, the middle and upper core wall filling area III-3 and the middle and upper downstream preliminary filling area III-2; The construction method comprises the following steps: Determine the main parameters of the dam material zoning design and the dam axis on both sides; Excavation of the dam foundation riverbed, including asphalt concrete core wall foundation and rockfill area foundation; Carry out foundation treatment of core wall corridor, construct anti-seepage wall, and pour foundation corridor; Construction of drainage facilities on earth foundations; The dam body and core wall to the rockfill foundation surface in the core pit filling layer area I shall be constructed in accordance with the rolling process parameters of the dam body filling materials in the core pit filling layer area I and the asphalt concrete construction process requirements; During construction, the upper and lower middle parts of the dam body filling layer II will be filled in Area II-1 and II-2 upstream and downstream to the designed filling top elevation; The middle and lower core wall filling area II-3 of the middle and lower dam body filling layer area II during construction, to the designed filling top elevation; Construct the middle and upper dam body filling layer area III according to the construction sequence of the middle and lower dam body filling layer area II; Construction top dam filling layer zone IV; Construct wave-breaking walls and ensure that the seepage control requirements between the wave-breaking walls and the asphalt concrete core wall are met; Construct dam top transition material and dam top pavement structure layer; The foundation curtain grouting construction is carried out through the foundation corridor.

Images