An ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions

Abstract

This invention discloses an ecological revetment structure for preventing frost heave and thaw settlement in high-altitude freeze-thaw regions. The structure includes: a frost heave-resistant foundation layer with a depth greater than the local maximum frost depth, comprising a gravel layer and a drainage layer; an insulation layer above the foundation layer, comprising a polystyrene foam insulation layer; a main ecological revetment structure above the insulation layer, comprising ecological gabion baskets filled with planting substrate and a geotextile filter layer; a drainage and seepage control system, comprising a longitudinal gravel drainage ditch on the backwater side of the revetment; a Linka-style wooden pile toe structure on the outer slope toe of the revetment, consisting of continuously arranged wooden piles; and a vegetation restoration layer on the main ecological revetment structure forming an ecological buffer zone, using a mixed sowing of native grass species. This invention effectively prevents frost heave and thaw settlement, maintaining ecological functions, and is suitable for riverbank protection projects in the Qinghai-Tibet Plateau and similar high-altitude cold regions.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering and ecological restoration technology, and in particular to an ecological bank protection structure for preventing frost heave and thaw settlement in plateau freeze-thaw regions. It is suitable for river valley and river channel bank protection projects with high altitude, seasonal permafrost development, large diurnal temperature differences, and significant water level fluctuations. Background Technology

[0002] In the Qinghai-Tibet Plateau and similar high-altitude and cold regions, river valley bank protection projects face severe challenges from seasonal permafrost and freeze-thaw cycles. Traditional bank protection methods, often employing rigid structures such as concrete and masonry, while resistant to erosion, obstruct water-soil-air exchange, hindering ecological restoration. Furthermore, they are prone to cracking and displacement under frost heave, and uneven settlement and bank instability during thaw settlement are common. On the other hand, while existing ecological bank protection methods (such as gabions and eco-bags) perform well in general areas, they fail in the high-altitude freeze-thaw environment if the foundation depth is insufficient or the fill material is improperly selected, leading to frost heave or thaw settlement collapse. Therefore, a bank protection structure that can resist frost heave and thaw settlement while maintaining ecological functions is urgently needed. Summary of the Invention

[0003] In view of this, the present invention provides an ecological bank protection structure for preventing frost heave and thaw settlement in plateau freeze-thaw regions, achieving resistance to frost heave and thaw settlement, maintaining ecological integrity and landscape integration.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: An ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions includes: The frost-resistant foundation layer has a foundation depth greater than the local maximum frost depth. The frost-resistant foundation layer includes a gravel layer set at the bottom of the foundation and a seepage-proof and drainage layer laid at the bottom of the gravel layer. A thermal insulation partition layer is provided above the anti-frost heave base layer, including a polystyrene foam board insulation layer; The main structure of the ecological revetment is set above the thermal insulation layer, including ecological gabion cages. A geotextile filter layer is set on the side of the ecological gabion cage that is in contact with the soil layer, and the gaps in the ecological gabion cage are filled with planting substrate. Drainage and seepage control system, including longitudinal gravel drainage ditches located on the backwater side of the revetment; The Linka-style wooden pile toe protection structure is set at the outer slope toe of the main ecological revetment structure, and includes multiple wooden piles driven into the soil and continuously arranged along the slope toe.

[0005] Preferably, the foundation depth is ≥ the local maximum frost depth + 0.2m.

[0006] Preferably, the thickness of the gravel layer is 30–50 cm, the relative density is ≥0.60, and the permeability coefficient is ≥200 m / d; the seepage-proof drainage layer consists of an inner layer of 200 g / m³. 2 Geotextile, 0.8mm thick HDPE membrane in the middle layer, and 200g / m² outer layer 2 Geotextile is composed of...

[0007] Preferably, the polystyrene foam board insulation layer has a thickness of 10–15 cm and a thermal conductivity ≤0.035 W / (m·K), and is wrapped with a protective layer of 400 g / m². 2 Geotextile.

[0008] Preferably, the main body of the ecological gabion is made of galvanized wire mesh with a mesh size of 60×80mm, a wire diameter of φ3.2mm, a frame wire diameter of φ4.0mm, a tensile strength ≥420MPa, and a galvanizing amount ≥240g / m². 2 The ecological gabion is filled with local stones with a particle size of 10-30cm, a single stone weight of ≥25kg, a compressive strength of ≥Mu40MPa, and a non-uniformity coefficient of ≥5.

[0009] Preferably, the geotextile filter layer is made of 400g / m³. 2 The substrate is composed of geotextile; the planting substrate is a mixture of humus and organic fertilizer, with a volume ratio of humus to organic fertilizer of 3:1 to 4:1, and the organic fertilizer is cow or sheep manure.

[0010] Preferably, the longitudinal gravel drainage ditch has a cross-section of 30×40cm, is filled with 20-40 mm gravel, and has a filter layer at the bottom with a density of 400 g / m³. 2 Geotextile, longitudinal slope of longitudinal crushed stone drainage ditch ≥1%.

[0011] Preferably, the wooden piles are 80-100cm long and 10cm in diameter. The depth of the piles driven into the soil is not less than 2 / 3 of their length, forming a double-row continuous pile array. The inner piles are closely fitted with the anti-frost heave and thaw settlement structure layer and gabion stone cages, while the top of the outer piles is level with the normal water level. The spacing between adjacent wooden piles is 5cm. The wooden piles are made of local wood that has undergone anti-corrosion treatment, specifically one or more of alpine pine, spruce, fir, or pine.

[0012] Furthermore, the anti-corrosion treatment employs environmentally friendly wood preservatives through vacuum pressure impregnation.

[0013] Preferably, it also includes a vegetation restoration layer, which is set on the main structure of the ecological revetment to form an ecological buffer zone. The ecological buffer zone uses a mixture of native grass species sown in the planting substrate.

[0014] Furthermore, the native grass species are a mixture of Chinese fescue, crested wheatgrass, tall fescue, and cosmos in a 1:1:1:1 ratio, with a sowing rate of 45 g / m². 2 .

[0015] As can be seen from the above technical solution, compared with the prior art, the present invention discloses an ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions, which has the following beneficial effects: It has excellent resistance to frost heave and thaw settlement: the foundation depth is greater than the maximum frost depth, and with the sand and gravel layer and the seepage prevention and drainage layer, the frost heave force does not directly act on the main body of the revetment; the thermal insulation layer further reduces the impact of frost depth, and the drainage is unobstructed during the thaw settlement period to avoid water pressure rise.

[0016] Complete ecological function: Ecological gabion cages combined with planting substrate provide growth conditions for vegetation. The vegetation restoration layer uses native grass species mixed in the planting substrate to form an ecological buffer zone, effectively restoring vegetation and enhancing soil and water conservation capacity.

[0017] Stable and durable structure: The Linka-style wooden pile toe protection structure enhances the slope's resistance to erosion and works in conjunction with gabion revetments to improve overall stability.

[0018] Economically feasible: Local materials are used (local boulders, gravel, native timber), construction techniques are mature, and it is suitable for the plateau environment. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is an overall structural diagram of an ecological bank protection structure for preventing frost heave and thaw settlement in plateau freeze-thaw regions according to the present invention; In the diagram: 1-frost heave prevention base layer, 11-gravel layer, 12-seepage prevention and drainage layer, 2-thermal insulation layer, 21-thermal insulation layer, 22-protective layer, 3-ecological revetment main body, 31-ecological gabion, 32-geotextile filter layer, 4-gravel drainage ditch, 41-filter layer, 5-linka-style wooden pile toe protection. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 Combined with appendix Figure 1 The structure shown is specifically applied in the Zhalanggou ecological restoration project: I. Structural Parameter Design Frost-heave-resistant foundation layer 1: Maximum frost depth in the project area is 1.3m, and the designed foundation burial depth is 1.5m; Gravel layer 11: 40cm thick, using well-graded natural gravel, with a relative density controlled at 0.62 and a permeability coefficient ≥200m / d. Seepage-proof drainage layer 12: Two layers of fabric and one membrane: inner layer 200g / m³. 2 Geotextile, 0.8mm thick HDPE membrane in the middle layer, and 200g / m² outer layer. 2 Geotextile.

[0023] Thermal insulation layer 2: includes insulation layer 21 and protective layer 22. The insulation layer is made of polystyrene foam board (EPS), with a thickness of 12cm and a thermal conductivity of 0.033W / (m·K). The protective layer is a 400g / m² protective layer wrapped around the outside of the insulation layer. 2 Geotextile.

[0024] Ecological bank protection structure 3: Ecological gabion 31 cages are made of hot-dip galvanized iron wire mesh, with a mesh size of 60×80mm, iron wire φ3.2mm, frame φ4.0mm, tensile strength ≥420MPa, and galvanizing amount ≥240g / m². 2 The gabion cages are 1.5×1.0×1.0m in size, filled with local granite boulders with a particle size of 10-30cm, a single block weight ≥25kg, a compressive strength of Mu40, and a uniformity coefficient ≥5. A geotextile filter layer of 32 gabion (400g / m²) is laid on the side of the gabion cage in contact with the soil. 2 The gaps in the gabions are filled with a planting substrate, which is a mixture of humus and cow / sheep manure organic fertilizer in a volume ratio of 3:1.

[0025] Drainage and seepage control system: A longitudinal gravel drainage ditch 4 with a cross-section of 30×40cm is constructed on the backwater side of the revetment, filled with 20-40mm gravel, and a filter layer 41 (400g / m²) is laid at the bottom and around the ditch. 2 Geotextile), with a longitudinal slope of 1.5% for the gravel drainage ditch.

[0026] Linka-style wooden pile toe protection 5: The wooden piles are 90cm long and 10cm in diameter. They are made of local high-mountain pine wood and are treated with environmentally friendly wood preservatives under vacuum pressure. The wooden piles are driven vertically into the soil along the slope toe to a depth of 60cm, forming a double row of continuous piles. The inner piles are tightly fitted with the anti-frost heave and thaw settlement structure layer and gabion stone cages, while the top of the outer piles is level with the normal water level. The spacing between adjacent piles is 5cm.

[0027] Vegetation restoration layer: Native grass seeds are sown on the main structure of the ecological revetment, namely the top and outer planting substrate of the gabion cages, to form an ecological buffer zone. The native grass seeds are Chinese fescue, crested wheatgrass, tall fescue, and cosmos in a 1:1:1:1 ratio, with a sowing rate of 45g / m². 2 After sowing, cover the soil with non-woven fabric to retain moisture.

[0028] II. Construction Method Construction should be carried out during the dry season to avoid working during the peak freeze-thaw period.

[0029] Surveying and setting out and foundation excavation: Set out the river bottom line and embankment line according to the design, select the dry season for construction, use an excavator to clear the foundation to the design elevation (foundation depth 1.5m), remove silt, weeds and weak soil layers, and level the foundation; Construction of the anti-frost heave base layer: First, lay a gravel layer 11, using well-graded natural gravel, laid in layers, and compacted in layers with a vibratory roller until the relative density reaches 0.62 or higher and the permeability coefficient is ≥200m / d; Then lay the seepage-proof and drainage layer 12, and lay two layers of cloth and one membrane (200g / m²) on the compacted gravel layer. 2 Geotextile + 0.8mm HDPE membrane + 200g / m 2 Geotextile). The overlap width between two adjacent geotextiles and membranes shall be ≥20cm, and hot-melt welding shall be used to ensure a tight joint; Construction of the thermal insulation layer: Polystyrene foam board (EPS) is laid on top of the waterproofing and drainage layer as the insulation layer 21, with a thickness of 12cm. It is cut on-site and laid tightly against the top surface of the foundation. The joints between the boards are sealed with tape to prevent thermal bridging. A 400g / m² insulation layer is then wrapped around the outside of the insulation layer. 2 Geotextile is used as a protective layer 22 and is secured with nylon rope or wire to prevent it from being punctured and damaged by gravel. Construction of the main structure of the ecological revetment: Gabion cages 31 are pre-assembled on the bank. The mesh is unfolded, and adjacent faces are connected with binding wire to form cubic cages. Empty cages are hoisted to the designed location (above the insulation layer) and connected to adjacent cages with double-strand galvanized lead wire. Local boulders are manually filled in, first arranging larger boulders neatly on the outer surface to ensure a flat appearance, then filling the inner boulders with staggered joints between layers. Deformation of the cages is avoided during filling. A geotextile filter layer 32 (400g / m²) is laid on the side of the gabion cage in contact with the soil (the bank side). 2 ; Fill the gaps in the gabions with planting substrate (humus: cow and sheep manure = 3:1) and compact it. Construction of Drainage and Seepage Guidance System: Preparation of Longitudinal Crushed Stone Drainage Ditch 4: Excavate a trench with a cross-section of 30×40cm on the backwater side of the revetment, and lay 400g / m³ gravel on the bottom and sides of the trench. 2 Geotextile is used as the filter layer 41, and then 20-40mm crushed stone is filled in to ensure that the longitudinal slope of the crushed stone drainage ditch is ≥1%.

[0030] Construction of Linka-style wooden pile toe protection 5: Select alpine pine piles that have been vacuum-pressurized and treated with environmentally friendly wood preservatives, with a length of 90cm and a diameter of 10cm. Along the outer slope toe of the main structure of the ecological revetment, mark the piles at 5cm intervals. Use a pile driver or manual labor to drive the wooden piles vertically (or slightly inclined) into the soil to a depth of 60cm, forming a double row of continuous piles. The inner piles are closely attached to the anti-frost heave and thaw settlement structure layer and gabion stone cages, while the top of the outer piles is level with the normal water level.

[0031] Vegetation restoration layer construction: Evenly sow mixed grass seeds (Chinese fescue: crested wheatgrass: tall fescue: cosmos = 1:1:1:1) on the planting substrate surface of the top and outside of the ecological gabion 31, at a sowing rate of 45g / m². 2 After sowing, cover the soil with a layer of non-woven fabric or fine sand to retain moisture, and then sprinkle water for maintenance.

[0032] Quality control and acceptance: Check whether the foundation depth reaches 1.5m, whether the insulation layer is intact and undamaged, the stability of the gabion (no deformation, no stone leakage), and whether the filter layer is laid in place.

[0033] Structural stability verification should be performed: anti-slip safety factor should be ≥1.2, anti-tilting safety factor should be ≥1.4, and permeability gradient should be ≤0.12.

[0034] Vegetation coverage requirements: ≥75% seedling emergence rate in the current year, and ≥60% vegetation coverage rate after a 5-year maintenance period.

[0035] III. Monitoring Results After the structure was completed according to the above construction method, monitoring showed that the anti-slip safety factor was 1.344 (normal use) / 1.82 (non-normal use), the anti-tilting safety factor was 4.406 / 17.089, and the permeability ratio was 0.09 (less than the allowable value of 0.12). No frost heave or thaw settlement occurred. The vegetation restoration layer grew well, the structure was stable, and the ecological benefits were significant.

[0036] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions, characterized in that, include: The frost-resistant foundation layer has a foundation depth greater than the local maximum frost depth. The frost-resistant foundation layer includes a gravel layer set at the bottom of the foundation and a seepage-proof and drainage layer laid at the bottom of the gravel layer. A thermal insulation partition layer is provided above the anti-frost heave base layer, including a polystyrene foam board insulation layer; The main structure of the ecological revetment is set above the thermal insulation layer, including ecological gabion cages. A geotextile filter layer is set on the side of the ecological gabion cage that is in contact with the soil layer, and the gaps in the ecological gabion cage are filled with planting substrate. Drainage and seepage control system, including longitudinal gravel drainage ditches located on the backwater side of the revetment; The Linka-style wooden pile toe protection structure is set at the outer slope toe of the main ecological revetment structure, and includes multiple wooden piles driven into the soil and continuously arranged along the slope toe.

2. The ecological bank protection structure for preventing frost heave and thaw settlement in plateau freeze-thaw regions according to claim 1, characterized in that, The foundation depth is ≥ the local maximum frost depth + 0.2m.

3. The ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions according to claim 1, characterized in that, The gravel layer has a thickness of 30–50 cm, a relative density ≥0.60, and a permeability coefficient ≥200 m / d; the seepage-proof drainage layer consists of an inner layer of 200 g / m³. 2 Geotextile, 0.8mm thick HDPE membrane in the middle layer, and 200g / m² outer layer 2 Geotextile is composed of geotextile.

4. The ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions according to claim 1, characterized in that, The polystyrene foam board insulation layer has a thickness of 10–15 cm and a thermal conductivity ≤0.035 W / (m·K). The insulation layer is wrapped with a protective layer of 400 g / m². 2 Geotextile.

5. The ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions according to claim 1, characterized in that, The main body of the ecological gabion cage is made of galvanized iron wire mesh with a mesh size of 60×80mm, a wire diameter of φ3.2mm, a frame wire diameter of φ4.0mm, a tensile strength ≥420MPa, and a galvanizing amount ≥240g / m². 2 The ecological gabion is filled with local stones with a particle size of 10-30cm, a single stone weight of ≥25kg, a compressive strength of ≥Mu40MPa, and a non-uniformity coefficient of ≥5.

6. The ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions according to claim 1, characterized in that, The geotextile filter layer is made of 400g / m 2 The substrate is composed of geotextile; the planting substrate is a mixture of humus and organic fertilizer, with a volume ratio of humus to organic fertilizer of 3:1 to 4:1, and the organic fertilizer is cow or sheep manure.

7. The ecological bank protection structure for preventing frost heave and thaw settlement in plateau freeze-thaw regions according to claim 1, characterized in that, The longitudinal gravel drainage ditch has a cross-section of 30×40cm, is filled with 20-40 mm gravel, and has a filter layer at the bottom with a density of 400g / m³. 2 Geotextile, longitudinal slope of longitudinal crushed stone drainage ditch ≥1%.

8. The ecological bank protection structure for preventing frost heave and thaw settlement in plateau freeze-thaw regions according to claim 1, characterized in that, The wooden piles are 80-100cm long and 10cm in diameter. The depth of the piles driven into the soil is not less than 2 / 3 of their length, forming a double row of continuous piles. The inner piles are closely attached to the anti-frost heave and thaw settlement structure layer and gabion stone cages, while the top of the outer piles is level with the normal water level. The spacing between adjacent piles is 5cm. The wooden piles are made of local wood that has been treated with preservatives, specifically one or more of alpine pine, spruce, fir, or pine.

9. The ecological bank protection structure for preventing frost heave and thaw settlement suitable for plateau freeze-thaw regions according to claim 1, characterized in that, It also includes a vegetation restoration layer, which is set on the main structure of the ecological revetment to form an ecological buffer zone. The ecological buffer zone uses a mixture of native grass species sown in the planting substrate.

10. A frost heave and thaw resistance structure for ecological bank protection in plateau freeze-thaw regions according to claim 9, characterized in that, The native grass species are a mixture of Chinese fescue, crested wheatgrass, tall fescue, and cosmos in a 1:1:1:1 ratio, with a sowing rate of 45 g / m². 2 .

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