A modified phosphogypsum mine ecological restoration anti-settling composite anti-seepage structure

Abstract

This utility model proposes a modified phosphogypsum mine ecological restoration anti-settlement composite seepage-proof structure, belonging to the field of mine ecological restoration technology. It includes a base layer, an anti-settlement layer, a clay cushion layer, and a seepage-proof layer laid from bottom to top. The base layer consists of a backfill layer and a layered compacted layer laid on top of the backfill layer. The clay cushion layer is a layered compacted clay cushion layer. The seepage-proof layer includes a first geotextile layer, a geomembrane layer, and a second geotextile layer from bottom to top. This utility model can solve the technical problem of seepage-proof membrane damage and seepage-proof system failure caused by base layer settlement.

Description

Technical Field

[0001] This utility model relates to the field of mine ecological restoration technology, specifically to a modified phosphogypsum mine ecological restoration anti-settlement composite seepage prevention structure. Background Technology

[0002] In recent years, using modified phosphogypsum as a filler material for the ecological restoration of abandoned mines has become an important way to utilize industrial solid waste resources. In such restoration projects, in order to prevent harmful substances in the filler from leaking out and polluting groundwater and soil, it is usually necessary to lay an anti-seepage system at the bottom of the mine pit.

[0003] Existing seepage prevention systems typically employ composite structures, such as a combined seepage prevention system consisting of a compacted clay cushion layer, a high-density polyethylene (HDPE) geomembrane, and a non-woven geotextile protective layer. This structure can effectively prevent seepage in conventional backfilling projects.

[0004] However, in some large-scale mine remediation projects, the thickness of the foundation backfill layer may reach more than 30 meters. The huge pressure of subsequent large-scale modified phosphogypsum filling and the problem of uneven settlement of the thick foundation layer can lead to the HDPE geomembrane and other seepage prevention materials above it breaking or being damaged, forming seepage channels and causing environmental risks of polluting groundwater and soil. Utility Model Content

[0005] In order to overcome the problems in the background technology, this utility model provides a modified phosphogypsum mine ecological restoration anti-settlement composite seepage prevention structure, which solves the technical problems of seepage prevention membrane damage and seepage prevention system failure caused by foundation layer settlement.

[0006] The modified phosphogypsum mine ecological restoration anti-settlement composite seepage prevention structure includes a base layer, an anti-settlement layer, a clay cushion layer, and a seepage prevention layer laid sequentially from bottom to top; the base layer consists of a backfill layer and a layered compacted layer laid on top of the backfill layer; the clay cushion layer is a layered compacted clay cushion layer; and the seepage prevention layer includes a first geotextile layer, a geomembrane layer, and a second geotextile layer from bottom to top.

[0007] Furthermore, the backfill layer is an artificial backfill layer consisting of stripped soil and compacted excavated rock.

[0008] Furthermore, the thickness of the layered compacted layer is not less than 2m, and the layered compacted layer is composed of stripped soil with a high soil content and excavated rock with a thickness not exceeding 0.5m.

[0009] Furthermore, the anti-settlement layer is a fixed mesh anti-settlement layer or a bidirectional geogrid anti-settlement layer.

[0010] Furthermore, the thickness of the clay cushion layer is not less than 100 cm, the thickness of each compacted layer is not more than 0.5 m, and the permeability coefficient of the clay cushion layer is not greater than 1.0 × 10⁻⁶. -7 cm / s.

[0011] Furthermore, the first and second geotextile layers of the impermeable layer have a strength of 400 g / m². 2 Polyester filament geotextile, wherein the geomembrane layer of the impermeable layer is a 1.5mm high-density polyethylene geomembrane.

[0012] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model improves the integrity and uniformity of the foundation layer surface by setting a layered compaction layer composed of a specially treated medium on top of the foundation layer, which provides a guarantee for the stability of the upper structure. At the same time, by adding an anti-settlement layer, it can effectively prevent the local subsidence of the clay cushion layer caused by uneven settlement of the foundation layer, and avoid stress concentration damage to the impermeable layer.

[0013] 2. The anti-settlement layer and the clay cushion layer of this utility model together form a flexible secondary seepage barrier. The clay cushion layer is compacted in layers and its permeability coefficient is controlled. When the pressure of the overlying fill is too high or an earthquake occurs, causing damage to the main seepage barrier layer (HDPE geomembrane), this flexible seepage barrier layer can still effectively prevent leachate from seeping down, greatly improving the reliability and safety of the entire seepage prevention system. Attached Figure Description

[0014] To clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the description of the embodiments are explained.

[0015] Figure 1 This is a schematic cross-sectional view of the structure of this utility model.

[0016] In the diagram: 1-Foundation layer, 11-Backfill layer, 12-Layered compacted layer, 2-Anti-settlement layer, 3-Clay cushion layer, 4-Imperile layer Detailed Implementation

[0017] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, so as to facilitate the understanding of those skilled in the art.

[0018] See Figure 1 This utility model proposes a modified phosphogypsum mine ecological restoration anti-settlement composite seepage prevention structure, which includes, from bottom to top, a base layer 1, an anti-settlement layer 2, a clay cushion layer 3 and a seepage prevention layer 4. The foundation layer 1 is the load-bearing foundation of the entire seepage prevention structure, located at the bottom of the mine pit. The foundation layer 1 consists of a lower backfill layer 11 and a top layered compacted layer 12. When dealing with large deep pits, the thickness of the backfill layer 11 is not less than 30m. The preferred material for the backfill layer 11 is mine stripped soil and excavated rock, which is compacted to form an artificial backfill layer. In order to improve the stability and integrity of the top of the foundation layer 1, the top layered compacted layer 12 of the foundation layer 1 is specially treated: the thickness is not less than 2m, and it uses stripped soil and excavated rock with a high soil content, and is compacted in layers with a thickness not exceeding 0.5m to ensure the compactness and uniformity of the top foundation. See Figure 1 A settlement prevention layer 2 is laid on top of the foundation layer 1. The settlement prevention layer 2 is preferably a fixed mesh or TGSG30-30 bidirectional geogrid to enhance the structural integrity of the clay cushion layer 3. When the foundation layer 1 experiences local uneven settlement, the settlement prevention layer 2 can prevent the clay cushion layer 3 from collapsing due to its tensile strength, thus avoiding stress concentration and transmission to the upper impermeable layer 4. At the same time, the settlement prevention layer 2 also serves as a flexible impermeable barrier, playing a secondary impermeable role in the extreme case of failure of the main impermeable layer, preventing pollutants from seeping down. See Figure 1 On top of the anti-settlement layer 2, a clay cushion layer 3 is laid with a thickness of not less than 100cm. It is laid using a layered compaction method, with each layer compacted to a thickness not exceeding 0.5m to ensure uniformity and density. After compaction, the saturated permeability coefficient of the clay cushion layer 3 is not greater than 1.0×10⁻⁶. -7 cm / s, forming a low-permeability seepage barrier; See Figure 1 On top of the clay cushion layer 3, the main seepage barrier layer 4 is laid. The seepage barrier layer 4 is a composite structure of two geotextile layers and one geomembrane layer, which includes a first geotextile layer, a geomembrane layer and a second geotextile layer from bottom to top. The first geotextile layer and the second geotextile layer are preferably made of 400g / m² polyester filament geotextile, which plays a protective and filtering role. The geomembrane layer in the middle is preferably made of 1.5mm thick HDPE geomembrane, which has extremely low permeability and excellent chemical corrosion resistance.

[0019] Work process: After the mine pit is backfilled and modified phosphogypsum is piled up, the load of the piled material is transferred to the foundation layer 1 through the impermeable layer 4 and the clay cushion layer 3. When the thick backfill layer 11 settles unevenly, it will form a local depression on the surface of the layered compacted layer 12 on top. At this time, the anti-settlement layer 2 laid on it plays its tensile resistance role, dispersing the load of the upper clay cushion layer 3 to the surrounding non-settled areas, thereby preventing the clay cushion layer 3 from sinking with the foundation layer and avoiding the formation of concentrated tensile stress on the geomembrane of the impermeable layer 4. This effectively prevents the geomembrane from being damaged and broken due to excessive deformation, ensuring the integrity of the main impermeable system. In extreme cases, even if the geomembrane layer is damaged, the flexible impermeable layer formed by the thickened clay cushion layer 3 and the anti-settlement layer 2 can still serve as a second line of defense, effectively blocking the infiltration of leachate, thus achieving double protection and ensuring the long-term environmental safety of the entire ecological restoration project.

[0020] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A modified phosphogypsum mine ecological restoration anti-settling composite impermeable structure, characterized in that, It includes a base layer (1), an anti-settlement layer (2), a clay cushion layer (3), and an impermeable layer (4) laid from bottom to top. The base layer (1) consists of a backfill layer (11) and a layered compacted layer (12) laid on top of the backfill layer (11). The clay cushion layer (3) is a layered compacted clay cushion layer. The impermeable layer (4) includes a first geotextile layer, a geomembrane layer, and a second geotextile layer from bottom to top.

2. The modified phosphogypsum mine ecological restoration anti-settling composite impermeable structure according to claim 1, characterized in that, The backfill layer (11) is an artificial backfill layer consisting of stripped soil and compacted excavated rock.

3. The modified phosphogypsum mine ecological restoration anti-settling composite impermeable structure according to claim 1, characterized in that, The thickness of the layered compacted layer (12) is not less than 2m, and the layered compacted layer (12) is composed of stripped soil with a high soil content and waste rock with a thickness not exceeding 0.5m.

4. The anti-settlement composite seepage-proof structure for ecological restoration of modified phosphogypsum mines according to claim 1, characterized in that, The anti-settlement layer (2) is a fixed net anti-settlement layer or a two-way geogrid anti-settlement layer.

5. The anti-settlement composite seepage-proof structure for ecological restoration of modified phosphogypsum mines according to claim 1, characterized in that, The thickness of the clay cushion layer (3) is not less than 100 cm, the thickness of each layer of the clay cushion layer (3) after compaction is not higher than 0.5 m, and the permeability coefficient of the clay cushion layer (3) is not greater than 1.0 × 10⁻⁶. -7 cm / s.

6. The anti-settlement composite seepage-proof structure for ecological restoration of modified phosphogypsum mines according to claim 1, characterized in that, The first and second geotextile layers of the impermeable layer (4) have a strength of 400 g / m². 2 Polyester filament geotextile, wherein the geomembrane layer of the impermeable layer (4) is a 1.5mm high-density polyethylene geomembrane.

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