Leveling device and method for broken stone hardcore of dam slope of box dam

Abstract

The invention discloses a box dam slope broken stone hardcore leveling device and method. The box dam slope broken stone hardcore leveling device is characterized in that an interception net is laid on composite geotechnical cloth; the side face of the dam foot tooth wall, the side face of the dam crest anti-seepage wall and the side face of the lattice bank are each provided with an embedded positioning piece used for fixing the intercepting nets, and the medium-coarse sand cushion layer is provided with a supporting and fixing piece used for supporting the intercepting nets and an arc-shaped supporting rod used for connecting every two adjacent intercepting nets. The intercepting net comprises a large-hole iron net and a small-hole iron net, large-diameter broken stones are laid between the large-hole iron net and the composite geotechnical cloth, and small-diameter broken stones are laid between the small-hole iron net and the large-hole iron net. The method comprises the following steps: 1, grading pretreatment; 2, laying a large-diameter gravel layer; and 3, paving a small-diameter gravel layer, and combining to form a gravel hardcore. According to the method, the interception net is laid firstly, then the gravels are filled for compaction, the flatness problem during slope surface gravels leveling is effectively solved, reworking is avoided, and the cost is saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of cofferdam slope construction, and particularly relates to a device and method for leveling a crushed stone cushion layer on a cofferdam slope. Background Art

[0002] In the construction of a cofferdam slope, crushed stone leveling is a key process to ensure the uniformity, drainage performance, and structural stability of the cushion layer.

[0003] In the construction of a cofferdam slope, crushed stone leveling is a key link in constructing a stable dam body structure. The crushed stone cushion layer plays multiple roles through its unique physical properties: First, the crushed stone layer has excellent drainage performance, which can quickly drain the seepage water inside the dam body, reduce the pore water pressure, and thus effectively reduce the risk of seepage failure; Second, the interlocking effect between crushed stone particles can achieve stress dispersion, avoid load concentration in local areas, and significantly improve the overall stability of the slope; In addition, the crushed stone layer can act as an isolation layer to protect the underlying soil, prevent the slope protection structure (such as concrete facing or ecological grid) from directly contacting the soil, and reduce erosion damage caused by water flow scouring and freeze-thaw cycles.

[0004] Traditional crushed stone leveling construction usually follows a standardized process. At the initial stage of construction, the excavator dumps the graded crushed stone on the slope, and manual preliminary spreading is used to control the thickness. At this time, a 5 - 8 cm allowance is usually reserved for the thickness of the crushed stone layer. Subsequently, it enters the rough leveling stage, and a simple scraper device or a modified excavator bucket is used for the first leveling, focusing on eliminating obvious protrusions and depressions. The compaction process uses a vibratory roller for layered compaction. For steep slopes with a ratio of 1:3, a small hand-held vibratory rammer is used instead. By controlling the number of compaction passes (usually 3 - 5 passes) and the excitation force (20 - 30 kN), the compaction degree is ensured to reach more than 90%. Finally, manual fine leveling is carried out. Workers use a laser level for auxiliary positioning and cooperate with a scraping ruler to perform millimeter-level trimming on the slope, focusing on processing the blind areas of mechanical operations and joint parts, and finally controlling the slope error within the range of ±1.5% of the design requirements. The entire process needs to be combined with real-time quality inspection, and the density is measured by the sand replacement method to ensure that the crushed stone layer meets the established engineering mechanical property indicators.

[0005] When constructing and leveling, when traditional excavators and rollers operate on a 1:3 steep slope, it is easy to have poor leveling accuracy and even the risk of equipment slipping due to the center of gravity shift. Therefore, during leveling, manual leveling is often required. However, a large amount of manual trimming is required for steep slope leveling, resulting in low efficiency and large fluctuations in flatness (more than ±10 cm). Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a leveling device for the gravel cushion layer on the dam slope of a cofferdam. By setting a large-hole iron net and a small-hole iron net, it is convenient to intercept gravel in layers. By setting pre-buried positioning parts and support fixing parts, the height range of the gravel cushion layer is clearly pre-limited and a space is reserved, which is convenient for popularization and use.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a leveling device for the gravel cushion layer on the dam slope of a cofferdam. A toe wall is provided at the lower end of the dam slope, an anti-seepage wall is provided at the upper end of the dam slope, a plurality of grid ridges are provided between the top and bottom of the dam slope, a medium-coarse sand cushion layer and a composite geotextile are sequentially covered on the dam slope, and the leveling device includes an interception net laid above the composite geotextile;

[0008] Pre-buried positioning parts for fixing the interception net are provided on the side surfaces of the toe wall, the anti-seepage wall, and the grid ridges. Support fixing parts for supporting the interception net and arc-shaped struts for connecting adjacent two interception nets are provided on the medium-coarse sand cushion layer;

[0009] The interception net includes a large-hole iron net and a small-hole iron net located above the large-hole iron net. The numbers of the large-hole iron net and the small-hole iron net are both multiple and are arranged in a grid pattern. Large-diameter gravel is laid between the large-hole iron net and the composite geotextile, and small-diameter gravel is laid between the small-hole iron net and the large-hole iron net.

[0010] Further, the pre-buried positioning part includes an anchor plate and anchor bars provided on one side of the anchor plate. The anchor bars are anchored into the side surfaces of the toe wall, the anti-seepage wall, and the grid ridges. A card slot is horizontally opened on the other side of the anchor plate. A trapezoidal slot for hanging the small-hole iron net and the large-hole iron net is opened at the bottom of the card slot, and a card board for blocking the card slot is inserted into the trapezoidal slot.

[0011] Further, the support fixing part includes a first vertical rod, a first support ring and a second support ring provided on the upper part of the first vertical rod. A first bottom plate buried in the medium-coarse sand cushion layer is provided at the lower part of the first vertical rod. The first vertical rod is a hollow inner threaded rod. A first threaded rod extending into the top of the first vertical rod is provided at the lower part of the second support ring. The inner side wall of the first support ring is connected to the outer side wall of the first vertical rod through a plurality of first connecting rods, and the inner side wall of the second support ring is connected to the outer side wall of the first threaded rod through a plurality of second connecting rods.

[0012] Further, the arc-shaped strut includes a second vertical rod, and a first arc-shaped rod and a second arc-shaped rod disposed on the upper part of the second vertical rod. The number of the first arc-shaped rod and the second arc-shaped rod is two each, and they are symmetrically arranged on both sides of the second vertical rod. A second bottom plate embedded in the medium coarse sand cushion layer is disposed at the lower part of the second vertical rod. The second vertical rod is a hollow internal threaded rod. A second threaded rod extending into the top of the second vertical rod is disposed at the lower part of the second arc-shaped rod. The inner side wall of the first arc-shaped rod is connected to the outer side wall of the second vertical rod through a first extension rod, and the inner side wall of the second arc-shaped rod is connected to the outer side wall of the second threaded rod through a second extension rod.

[0013] Further, arc-shaped grooves are disposed on the outer side walls of the first arc-shaped rod and the second arc-shaped rod, and the small-hole iron net and the large-hole iron net are abutted in the arc-shaped grooves.

[0014] Meanwhile, the present invention also discloses a method for leveling the crushed stone cushion layer of the dam slope, which has simple steps and convenient operation. The intercepted net laid flat is woven according to different sizes of the crushed stones, and the woven intercepted net is covered on the slope surface and kept at a set distance from the slope surface. Then, the crushed stones are introduced into the gap between the intercepted net and the slope surface. After the crushed stones are evenly distributed, the compaction work is carried out on the intercepted net, solving the flatness problem when leveling the crushed stones on the slope surface, avoiding rework at the same time, and saving the labor cost required for construction. The method includes the following steps:

[0015] Step 1. Classification and pretreatment:

[0016] Step 101. Divide the dam slope surface into a plurality of interlocking areas arranged in a grid pattern;

[0017] Step 102. Divide the crushed stone cushion layer to be laid into a large-diameter crushed stone layer and a small-diameter crushed stone layer;

[0018] Then, determine the particle size of the large-diameter crushed stones according to the design requirements of the large-diameter crushed stone layer, and determine the particle size of the small-diameter crushed stones according to the design requirements of the small-diameter crushed stone layer;

[0019] Then, weave a large-hole iron net according to the particle size of the large-diameter crushed stones, and weave a small-hole iron net according to the particle size of the small-diameter crushed stones;

[0020] Step 103. Mark the top surface design height of the large-diameter crushed stone layer as the first completion elevation and mark the top surface design height of the small-diameter crushed stone layer as the second completion elevation on the side surface of the dam toe tooth wall, the side surface of the dam top impervious wall, and the side surface of the grid dike;

[0021] Then, embed a first embedded positioning mechanism at the first completion elevation and embed a second embedded positioning mechanism at the second completion elevation;

[0022] Step 2. Lay the large-diameter crushed stone layer:

[0023] Step 201: Lay large-hole iron nets in each of the interlocking areas respectively: Lay the large-hole iron nets flat above the composite geotextile. The large-hole iron nets at the edges are fixed at the first completion elevation on the sides of the toe wall of the dam, the side of the anti-seepage wall at the dam top, and the side of the grid embankment through the first pre-buried positioning mechanism. The corners of the large-hole iron nets not connected to the first pre-buried positioning mechanism are supported above the composite geotextile by support fixing parts. The middle parts of two adjacent large-hole iron nets overlap with each other through arc-shaped struts to form a large-hole densification area;

[0024] Step 202: Lay large-diameter crushed stones between the large-hole iron nets and the composite geotextile and conduct the first compaction, and then fill the voids of the large-diameter crushed stones with filling materials and conduct the second compaction, so that the large-diameter crushed stones are densely distributed under the large-hole iron nets to form a large-diameter crushed stone layer;

[0025] Step Three: Lay a small-diameter crushed stone layer and combine them to form a crushed stone cushion layer:

[0026] Step 301: Lay multiple small-hole iron nets in each of the interlocking areas respectively: Lay the small-hole iron nets flat above the large-hole iron nets. The small-hole iron nets at the edges are fixed at the second completion elevation on the sides of the toe wall of the dam, the side of the anti-seepage wall at the dam top, and the side of the grid embankment through the second pre-buried positioning mechanism. The corners of the small-hole iron nets not connected to the second pre-buried positioning mechanism are supported above the large-hole iron nets by support fixing parts. The middle parts of two adjacent small-hole iron nets overlap with each other through arc-shaped struts to form a small-hole densification area;

[0027] Step 302: Lay small-diameter crushed stones between the small-hole iron nets and the large-hole iron nets and conduct the third compaction, and then fill the voids of the small-diameter crushed stones with filling materials and conduct the fourth compaction, so that the small-diameter crushed stones are densely distributed under the small-hole iron nets to form a small-diameter crushed stone layer;

[0028] Step 303: After all the pores on the surface of the small-diameter crushed stone layer are filled, conduct the fifth compaction with a smooth-wheel roller until the surface of the small-diameter crushed stone layer is flat and stable, without obvious wheel marks and without the phenomenon of stone creep, to form a flat crushed stone cushion layer.

[0029] Further, in Step 102, the large-diameter crushed stones are graded crushed stones with a particle size of 2 cm to 4 cm, and the small-diameter crushed stones are graded crushed stones with a particle size of 0.5 cm to 2 cm.

[0030] Further, in Step 103, the structural dimensions of the first pre-buried positioning mechanism and the second pre-buried positioning mechanism are the same;

[0031] The first pre-buried positioning mechanism includes a plurality of pre-buried positioning parts arranged along the edge of the large-hole iron net.

[0032] The present invention has the following advantages compared with the prior art:

[0033] 1. By setting a large-hole iron net and a small-hole iron net, the present invention facilitates the layered interception of crushed stones, sharing the stress of the crushed stones on one layer of the iron net by two layers of iron nets, and also facilitating the layered compaction of the crushed stone cushion, thereby reducing the thickness of the crushed stones that need to be compacted each time, and further reducing the vibration compaction force and the disturbance to other structures. It has strong practicability and is convenient for popularization and use.

[0034] 2. By pre-installing the embedded positioning parts at the marked positions and setting the support and fixing parts, the present invention facilitates the accurate and rapid installation of the large-hole iron net and the small-hole iron net at the specified height and position before filling the large-diameter crushed stones and small-diameter crushed stones, thus clearly limiting the height range of the crushed stone cushion, reserving the space for filling the large-diameter crushed stones and small-diameter crushed stones, and avoiding rework due to the excessive filling of the crushed stones. It has good use effect.

[0035] 3. Aiming at the problem of iron net laying on large-area dam slopes, the present invention divides the iron net into multiple interlocking areas. By setting arc-shaped struts, it is convenient to tie the middle parts of the large-hole iron nets in adjacent two interlocking areas and make them overlap, forming a large-hole encryption area and a small-hole encryption area, enhancing the density and coverage ability of the iron net at the connection, and preventing the crushed stones from showing and rolling out from the gaps of the iron net splicing.

[0036] 4. The method steps of the present invention are simple and the operation is convenient. According to the different sizes of large-diameter crushed stones and small-diameter crushed stones, large-hole iron nets and small-hole iron nets with different mesh sizes are woven. Then, the woven iron nets are laid flat to cover the slope surface of the dam slope and kept at a set distance from the slope surface. Then, the large-diameter crushed stones and small-diameter crushed stones are successively introduced into the gaps between the large-hole iron net and the small-hole iron net and the slope surface. After the large-diameter crushed stones and small-diameter crushed stones are evenly distributed, the compaction work is carried out on the large-hole iron net and the small-hole iron net successively, solving the flatness problem when leveling the crushed stones on the slope surface, and at the same time saving the labor cost required for construction, and being convenient for popularization and use.

[0037] In summary, for the device for leveling the crushed stone cushion of the dam slope adopted by the present invention, by setting a large-hole iron net and a small-hole iron net, it is convenient to intercept the crushed stones in layers. By setting the embedded positioning parts and the support and fixing parts, the height range of the crushed stone cushion is clearly pre-limited and the space is reserved; the adopted leveling method has simple steps and convenient operation. According to the different sizes of the crushed stones, the laid interception net is woven, and the woven interception net is covered on the slope surface and kept at a set distance from the slope surface. Then, the crushed stones are introduced into the gaps between the interception net and the slope surface. After the crushed stones are evenly distributed, the compaction work is carried out on the interception net, solving the flatness problem when leveling the crushed stones on the slope surface, avoiding rework, saving the labor cost required for construction, and being convenient for popularization and use.

[0038] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0039] Figure 1 This is a schematic structural diagram of the present invention.

[0040] Figure 2 This is a top view of the present invention with the small-hole iron mesh and the large-hole iron mesh removed.

[0041] Figure 3 This is a top view of the present invention with the small-hole iron mesh and the large-hole iron mesh laid.

[0042] Figure 4 This is a schematic structural diagram of the embedded positioning member of the present invention.

[0043] Figure 5 It is Figure 4 an enlarged view of part A of

[0044] Figure 6 This is a schematic structural diagram of the support and fixing member of the present invention.

[0045] Figure 7 This is a schematic structural diagram of the arc-shaped strut of the present invention.

[0046] Figure 8 This is a schematic structural diagram of the first arc-shaped rod and the second arc-shaped rod of the present invention.

[0047] Figure 9 This is a flowchart of the method of the present invention.

[0048] Description of reference numerals:

[0049] 1 - Dam slope; 2 - Toe wall of the dam; 3 - Anti-seepage wall on the dam crest;

[0050] 4 - Medium-coarse sand cushion layer; 5 - Composite geotextile; 6 - Large-diameter gravel;

[0051] 7 - Small-diameter gravel; 8 - Grid ridge; 9 - Interlocking area;

[0052] 10 - Large-hole iron mesh; 11 - Small-hole iron mesh; 12 - Large-hole encryption area;

[0053] 13 - Small-hole encryption area; 14 - Embedded positioning member; 15 - Support and fixing member;

[0054] 16 - Arc-shaped strut; 17 - Anchor plate; 18 - Anchor plate;

[0055] 19 - Clip plate; 20 - Card slot; 21 - Trapezoidal slot;

[0056] 22 - First bottom plate; 23 - First vertical rod; 24 - First support ring;

[0057] 25 - First connecting rod; 26 - First threaded rod; 27 - Second support ring;

[0058] 28—the second connecting rod; 29—the second bottom plate; 30—the second vertical rod;

[0059] 31—the first extension rod; 32—the first arc rod; 33—the second threaded rod;

[0060] 34—the second extension rod; 35—the second arc rod; 36—the arc groove. Specific embodiments

[0061] As Figures 1 to 8 shown, at the lower end of the dam slope 1, there is a toe slab 2, at the upper end of the dam slope 1, there is a top anti-seepage wall 3, between the top and bottom of the dam slope 1, there are multiple grid ridges 8, on the dam slope 1, there are successively covered with a medium-coarse sand cushion layer 4 and a composite geotextile 5. A leveling device for the crushed stone cushion layer of the dam slope of the present invention includes an interception net laid above the composite geotextile 5.

[0062] On the side surfaces of the toe slab 2, the top anti-seepage wall 3, and the grid ridge 8, there are embedded positioning members 14 for fixing the interception net. On the medium-coarse sand cushion layer 4, there are support fixing members 15 for supporting the interception net and arc struts 16 for connecting adjacent two interception nets.

[0063] The interception net includes a large-hole iron net 10 and a small-hole iron net 11 located above the large-hole iron net 10. The numbers of the large-hole iron net 10 and the small-hole iron net 11 are both multiple and are arranged in a grid pattern. Between the large-hole iron net 10 and the composite geotextile 5, there is a large-diameter crushed stone 6 laid, and between the small-hole iron net 11 and the large-hole iron net 10, there is a small-diameter crushed stone 7 laid.

[0064] When the present invention is used, by setting the large-hole iron net 10 and the small-hole iron net 11, it is convenient to intercept the crushed stone in layers, using two layers of iron nets to share the stress of the crushed stone on one layer of iron net, and it is also convenient to compact the crushed stone cushion layer in layers, thereby reducing the thickness of the crushed stone that needs to be compacted each time, and further reducing the vibration compaction force and the disturbance to other structures, with strong practicability.

[0065] As Figure 4 and Figure 5 shown, in this embodiment, the embedded positioning member 14 includes an anchor plate 17 and anchor bars 18 arranged on one side of the anchor plate 17. The anchor bars 18 are anchored into the side surfaces of the toe slab 2, the top anti-seepage wall 3, and the grid ridge 8. On the other side of the anchor plate 17, a card slot 20 is horizontally opened. At the bottom of the card slot 20, a trapezoidal slot 21 for hanging the small-hole iron net 11 and the large-hole iron net 10 is opened, and a card plate 19 for blocking the card slot 20 is inserted into the trapezoidal slot 21.

[0066] It should be noted that the height of the card slot 20 is less than the height of the card board 19, and the height of the card board 19 is adapted to the bottom side length of the cross-section of the trapezoidal slot 21, which is convenient for inserting the card board 19 into the trapezoidal slot 21 to block the card slot 20, so as to limit the iron wires at the edges of the large-hole iron net 10 and the small-hole iron net 11 in the trapezoidal slot 21 and realize the hanging connection of the large-hole iron net 10 and the small-hole iron net 11.

[0067] As Figure 6 shown, in this embodiment, the support and fixing member 15 includes a first vertical rod 23, a first support ring 24 and a second support ring 27 arranged on the upper part of the first vertical rod 23. A first bottom plate 22 embedded in the medium-coarse sand cushion layer 4 is arranged at the lower part of the first vertical rod 23. The first vertical rod 23 is a hollow internal threaded rod. A first threaded rod 26 extending into the top of the first vertical rod 23 is arranged at the lower part of the second support ring 27. The inner side wall of the first support ring 24 is connected to the outer side wall of the first vertical rod 23 through a plurality of first connecting rods 25. The inner side wall of the second support ring 27 is connected to the outer side wall of the first threaded rod 26 through a plurality of second connecting rods 28.

[0068] During actual use, by pre-installing the embedded positioning member 14 at the marked position and arranging the support and fixing member 15, it is convenient to accurately and quickly install the large-hole iron net 10 and the small-hole iron net 11 at the specified height and position before filling the large-diameter gravel 6 and the small-diameter gravel 7, thus clearly limiting the height range of the gravel cushion layer, reserving the space for filling the large-diameter gravel 6 and the small-diameter gravel 7, and avoiding rework due to the too-high filled gravel.

[0069] During actual construction, place the corner of the large-hole iron net 10 on the first support ring 24, and then use tools such as iron wires or cable ties to connect and fix the iron wire of the large-hole iron net 10 to the first support ring 24 and the first connecting rod 25 to realize the support of the large-hole iron net 10; place the corner of the small-hole iron net 11 on the second support ring 27, and then use tools such as iron wires or cable ties to connect and fix the iron wire of the small-hole iron net 11 to the second connecting rod 28 to realize the connection and fixing and the support of the small-hole iron net 11.

[0070] As Figure 7As shown in the figure, in this embodiment, the arc-shaped strut 16 includes a second vertical rod 30, a first arc rod 32 and a second arc rod 35 arranged on the upper part of the second vertical rod 30. The number of the first arc rod 32 and the second arc rod 35 is two each, and they are symmetrically arranged on both sides of the second vertical rod 30. A second bottom plate 29 embedded in the medium coarse sand cushion layer 4 is arranged at the lower part of the second vertical rod 30. The second vertical rod 30 is a hollow internal threaded rod. A second threaded rod 33 extending into the top of the second vertical rod 30 is arranged at the lower part of the second arc rod 35. The inner side wall of the first arc rod 32 is connected to the outer side wall of the second vertical rod 30 through a first extension rod 31. The inner side wall of the second arc rod 35 is connected to the outer side wall of the second threaded rod 33 through a second extension rod 34.

[0071] As Figure 8 shown in the figure, in this embodiment, arc-shaped grooves 36 are arranged on the outer side walls of the first arc rod 32 and the second arc rod 35. The small-hole iron net 11 and the large-hole iron net 10 are abutted in the arc-shaped grooves 36.

[0072] During actual use, for the problem of iron net laying on the large-area dam slope 1, the iron net is divided into multiple interlocking areas 9. By arranging the arc-shaped strut 16, it is convenient to pull and connect the middle parts of the large-hole iron nets 10 of two adjacent interlocking areas 9 and make them overlap, forming a large-hole encryption area 12 and a small-hole encryption area 13, enhancing the density and covering ability of the iron net at the connection, and preventing the crushed stones from showing and rolling out from the gaps of the spliced iron nets.

[0073] It should be noted that the iron wire of the large-hole iron net 10 on the left side of the second vertical rod 30 is clamped in the arc-shaped groove 36 of the first arc rod 32 on the right side, and then the iron wire of the large-hole iron net 10 on the right side of the second vertical rod 30 is clamped in the arc-shaped groove 36 of the first arc rod 32 on the left side, thereby realizing pulling and connecting the middle parts of the large-hole iron nets 10 of two adjacent interlocking areas 9 and making them overlap. The overlapping area is the large-hole encryption area 12, which is convenient for enhancing the density of the iron net at the connection position, and further enhancing the interception force on the large-diameter crushed stones 6.

[0074] Similarly, the iron wire of the small-hole iron net 11 on the left side of the second vertical rod 30 is clamped in the arc-shaped groove 36 of the second arc rod 35 on the right side, and then the iron wire of the small-hole iron net 11 on the right side of the second vertical rod 30 is clamped in the arc-shaped groove 36 of the second arc rod 35 on the left side, thereby realizing pulling and connecting the middle parts of the small-hole iron nets 11 of two adjacent interlocking areas 9 and making them overlap. The overlapping area is the small-hole encryption area 13, which is convenient for enhancing the density of the iron net at the connection position, and further enhancing the interception force on the small-diameter crushed stones 7.

[0075] As Figure 9 shown in the figure, a method for leveling the crushed stone cushion layer of the dam slope of the surrounding dam includes the following steps:

[0076] Step 1. Hierarchical preprocessing:

[0077] Step 101. Divide the dam slope surface into multiple interlocking areas 9 arranged in a grid pattern;

[0078] Step 102. Divide the gravel cushion layer to be laid into a large-diameter gravel layer and a small-diameter gravel layer;

[0079] Then determine the particle size of the large-diameter gravel 6 according to the design requirements of the large-diameter gravel layer, and determine the particle size of the small-diameter gravel 7 according to the design requirements of the small-diameter gravel layer;

[0080] Then weave a large-hole iron net 10 according to the particle size of the large-diameter gravel 6, and weave a small-hole iron net 11 according to the particle size of the small-diameter gravel 7;

[0081] Step 103. Mark the top surface design height of the large-diameter gravel layer as the first completion elevation on the side of the dam toe cut-off wall 2, the side of the dam top impervious wall 3, and the side of the grid dike 8, and mark the top surface design height of the small-diameter gravel layer as the second completion elevation;

[0082] Then embed a first pre-embedded positioning mechanism at the first completion elevation and embed a second pre-embedded positioning mechanism at the second completion elevation.

[0083] In this embodiment, in step 102, the large-diameter gravel 6 is graded gravel with a particle size of 2 cm to 4 cm, and the small-diameter gravel 7 is graded gravel with a particle size of 0.5 cm to 2 cm.

[0084] In actual use, there should be no sharp objects such as tree roots and other sundries in the gravel, and the grading should be good. The gravel volume of the large-diameter gravel 6 is equal to the gravel volume of the small-diameter gravel 7, that is, the thickness of the formed large-diameter gravel layer is equal to the thickness of the small-diameter gravel layer.

[0085] In this embodiment, in step 103, the structural dimensions of the first pre-embedded positioning mechanism and the second pre-embedded positioning mechanism are the same;

[0086] The first pre-embedded positioning mechanism includes a plurality of pre-embedded positioning parts 14 arranged along the edge of the large-hole iron net 10.

[0087] During actual construction, the sizes of the large-hole iron net 10 and the small-hole iron net 11 are slightly larger than the size of the interlocking area 9 to facilitate complete coverage of each interlocking area 9.

[0088] Step 2. Lay the large-diameter gravel layer:

[0089] Step 201: Lay large-hole iron nets 10 in each of the interlocking zones 9 respectively. Lay the large-hole iron nets 10 flat above the composite geomembrane 5. The large-hole iron nets 10 at the edges are fixed to the side surfaces of the dam toe cut-off wall 2, the dam top impervious wall 3, and the partition dike 8 at the first completion elevation through the first pre-buried positioning mechanism. The corners of the large-hole iron nets 10 not connected to the first pre-buried positioning mechanism are supported above the composite geomembrane 5 by the support fixing members 15. The middle parts of two adjacent large-hole iron nets 10 overlap each other through the arc-shaped struts 16 to form a large-hole dense area 12.

[0090] Step 202: Lay large-diameter crushed stones 6 between the large-hole iron nets 10 and the composite geomembrane 5 and conduct the first compaction. Then fill the voids in the large-diameter crushed stones 6 with filling materials and conduct the second compaction, so that the large-diameter crushed stones 6 are densely distributed under the large-hole iron nets 10 to form a large-diameter crushed stone layer.

[0091] During actual construction, in Step 202, when conducting the first compaction and the second compaction, due to the relatively large particle size of the large-diameter crushed stones 6 and the relatively large voids between the large-diameter crushed stones 6, it is preferably to use an 8 - 10t static tandem roller or a 5t vibratory roller for rapid rolling, so as to facilitate vibrating all the filling materials into the voids between the large-diameter crushed stones 6.

[0092] Step Three: Lay a small-diameter crushed stone layer and combine them to form a crushed stone cushion layer.

[0093] Step 301: Lay multiple small-hole iron nets 11 in each of the interlocking zones 9 respectively. Lay the small-hole iron nets 11 flat above the large-hole iron nets 10. The small-hole iron nets 11 at the edges are fixed to the side surfaces of the dam toe cut-off wall 2, the dam top impervious wall 3, and the partition dike 8 at the second completion elevation through the second pre-buried positioning mechanism. The corners of the small-hole iron nets 11 not connected to the second pre-buried positioning mechanism are supported above the large-hole iron nets 10 by the support fixing members 15. The middle parts of two adjacent small-hole iron nets 11 overlap each other through the arc-shaped struts 16 to form a small-hole dense area 13.

[0094] Step 302: Lay small-diameter crushed stones 7 between the small-hole iron nets 11 and the large-hole iron nets 10 and conduct the third compaction. Then fill the voids in the small-diameter crushed stones 7 with filling materials and conduct the fourth compaction, so that the small-diameter crushed stones 7 are densely distributed under the small-hole iron nets 11 to form a small-diameter crushed stone layer.

[0095] Step 303: After all the pores on the surface of the small-diameter crushed stone layer are filled, use a smooth-wheel roller for the fifth compaction until the surface of the small-diameter crushed stone layer is flat and stable, without obvious wheel marks and without the phenomenon of stone creep, to form a flat crushed stone cushion layer.

[0096] During actual construction, in step 302, when the third compaction and the fourth compaction are carried out, since the particle size of the small-diameter gravel 7 is small and the gaps between the small-diameter gravel 7 are also small, it is preferably to use a 5t vibratory roller for compaction to avoid damage to the underlying large-diameter gravel layer caused by the excessive tonnage or strong vibration of the roller.

[0097] In step 303, when the fifth compaction is carried out, it is preferably to use a 12-15t static smooth-wheel roller for final compaction for 1-2 passes, which is convenient for making the small-diameter gravel layer flat and stable without obvious wheel marks.

[0098] The present invention weaves the large-hole iron net 10 and the small-hole iron net 11 with different mesh sizes according to the different gravel sizes of the large-diameter gravel 6 and the small-diameter gravel 7, then spreads the woven iron net flatly to cover the slope surface of the dam slope 1 and keeps a set distance from the slope surface, and then successively introduces the large-diameter gravel 6 and the small-diameter gravel 7 into the gaps between the large-hole iron net 10 and the small-hole iron net 11 and the slope surface. After the large-diameter gravel 6 and the small-diameter gravel 7 are evenly distributed, the compaction work is carried out on the large-hole iron net 10 and the small-hole iron net 11 successively, which solves the flatness problem when leveling the gravel on the slope surface and also saves the labor cost required for construction.

[0099] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A leveling device for the crushed stone cushion layer on the dam slope of a cofferdam. There is a toe wall (2) at the lower end of the dam slope (1), a dam top impervious wall (3) at the upper end of the dam slope (1). There are multiple grid ridges (8) arranged between the top and bottom of the dam slope (1). A medium-coarse sand cushion layer (4) and a composite geotextile (5) are successively covered on the dam slope (1). It is characterized in that: The leveling device includes an interception net laid above the composite geotextile (5); Embedded positioning members (14) for fixing the interception net are provided on the sides of the toe slab (2), the top dam impervious wall (3), and the grid dike (8). Support fixing members (15) for supporting the interception net and arc struts (16) for connecting two adjacent interception nets are provided on the medium-coarse sand cushion layer (4); The interception net includes a large-hole iron net (10) and a small-hole iron net (11) located above the large-hole iron net (10). The numbers of the large-hole iron net (10) and the small-hole iron net (11) are both multiple and arranged in a grid pattern. Large-diameter gravels (6) are laid between the large-hole iron net (10) and the composite geotextile (5), and small-diameter gravels (7) are laid between the small-hole iron net (11) and the large-hole iron net (10).

2. The leveling device for the gravel cushion layer on the dam slope of the cofferdam according to claim 1, wherein: The embedded positioning member (14) includes an anchor plate (17) and anchor bars (18) provided on one side of the anchor plate (17). The anchor bars (18) are anchored into the sides of the toe slab (2), the top dam impervious wall (3), and the grid dike (8). A card slot (20) is horizontally opened on the other surface of the anchor plate (17). A trapezoidal slot (21) for hanging the small-hole iron net (11) and the large-hole iron net (10) is opened at the bottom of the card slot (20). A card plate (19) for blocking the card slot (20) is inserted into the trapezoidal slot (21).

3. A leveling device for the gravel cushion layer on the dam slope of a cofferdam according to claim 1, characterized in that: The support fixing member (15) includes a first vertical rod (23), a first support ring (24) and a second support ring (27) provided on the upper part of the first vertical rod (23). A first bottom plate (22) embedded in the medium-coarse sand cushion layer (4) is provided at the lower part of the first vertical rod (23). The first vertical rod (23) is a hollow internal threaded rod. A first threaded rod (26) extending into the top of the first vertical rod (23) is provided at the lower part of the second support ring (27). The inner side wall of the first support ring (24) is connected to the outer side wall of the first vertical rod (23) through a plurality of first connecting rods (25). The inner side wall of the second support ring (27) is connected to the outer side wall of the first threaded rod (26) through a plurality of second connecting rods (28).

4. A leveling device for the gravel cushion layer on the dam slope of a cofferdam according to claim 1, characterized in that: The arc-shaped strut (16) includes a second vertical rod (30), a first arc-shaped rod (32) and a second arc-shaped rod (35) arranged on the upper part of the second vertical rod (30). The number of the first arc-shaped rod (32) and the second arc-shaped rod (35) is two each, and they are symmetrically arranged on both sides of the second vertical rod (30). A second bottom plate (29) embedded in the medium coarse sand cushion layer (4) is arranged at the lower part of the second vertical rod (30). The second vertical rod (30) is a hollow internal threaded rod. A second threaded rod (33) extending into the top of the second vertical rod (30) is arranged at the lower part of the second arc-shaped rod (35). The inner side wall of the first arc-shaped rod (32) is connected to the outer side wall of the second vertical rod (30) through a first extension rod (31). The inner side wall of the second arc-shaped rod (35) is connected to the outer side wall of the second threaded rod (33) through a second extension rod (34).

5. The leveling device for the crushed stone cushion layer of the dam slope of the cofferdam according to claim 4, wherein: Arc-shaped grooves (36) are arranged on the outer side walls of the first arc-shaped rod (32) and the second arc-shaped rod (35). The small-hole iron mesh (11) and the large-hole iron mesh (10) are abutted in the arc-shaped grooves (36).

6. A method for leveling a dam slope by using the dam slope gravel cushion leveling device described in claim 1, characterized in that, This method includes the following steps: Step 1. Hierarchical pretreatment: Step 101. Divide the dam slope surface into a plurality of interlocking areas (9) arranged in a grid pattern; Step 102. Divide the gravel cushion layer to be laid into a large-diameter gravel layer and a small-diameter gravel layer; Then determine the particle size of the large-diameter gravel (6) according to the design requirements of the large-diameter gravel layer, and determine the particle size of the small-diameter gravel (7) according to the design requirements of the small-diameter gravel layer; Then weave the large-hole iron mesh (10) according to the particle size of the large-diameter gravel (6), and weave the small-hole iron mesh (11) according to the particle size of the small-diameter gravel (7); Step 103. Mark the top surface design height of the large-diameter gravel layer as the first completion elevation on the side surface of the dam toe cut-off wall (2), the side surface of the dam top impervious wall (3) and the side surface of the grid ridge (8), and mark the top surface design height of the small-diameter gravel layer as the second completion elevation; Then embed a first pre-embedded positioning mechanism at the first completion elevation, and embed a second pre-embedded positioning mechanism at the second completion elevation; Step 2. Lay the large-diameter gravel layer: Step 201. Lay the large-hole iron mesh (10) in each interlocking area (9) respectively: Lay the large-hole iron mesh (10) flat above the composite geotextile (5). The large-hole iron mesh (10) at the edge is fixed at the first completion elevation on the side surfaces of the dam toe cut-off wall (2), the dam top impervious wall (3) and the grid ridge (8) through the first pre-embedded positioning mechanism. The corners of the large-hole iron mesh (10) not connected to the first pre-embedded positioning mechanism are supported above the composite geotextile (5) through support fixing parts (15). The middle parts of two adjacent large-hole iron meshes (10) overlap each other through the arc-shaped strut (16) to form a large-hole encryption area (12); Step 202: Lay large-diameter crushed stones (6) between the large-hole iron mesh (10) and the composite geotextile (5) and conduct the first compaction, and then fill the gaps of the large-diameter crushed stones (6) with filling materials and conduct the second compaction, so that the large-diameter crushed stones (6) are densely distributed under the large-hole iron mesh (10) to form a large-diameter crushed stone layer; Step Three: Lay a small-diameter crushed stone layer and combine them to form a crushed stone cushion layer: Step 301: Lay a plurality of small-hole iron meshes (11) in each of the interlocking areas (9) respectively: Lay the small-hole iron meshes (11) flat on the upper part of the large-hole iron mesh (10). The small-hole iron meshes (11) located at the edge are fixed at the second completion elevation on the side of the dam toe tooth wall (2), the side of the dam top anti-seepage wall (3), and the side of the grid dike (8) through the second pre-buried positioning mechanism. The corners of the small-hole iron meshes (11) not connected to the second pre-buried positioning mechanism are supported above the large-hole iron mesh (10) by support fixing parts (15). The middle parts of two adjacent small-hole iron meshes (11) overlap each other through arc-shaped struts (16) to form a small-hole encryption area (13); Step 302: Lay small-diameter crushed stones (7) between the small-hole iron mesh (11) and the large-hole iron mesh (10) and conduct the third compaction, and then fill the gaps of the small-diameter crushed stones (7) with filling materials and conduct the fourth compaction, so that the small-diameter crushed stones (7) are densely distributed under the small-hole iron mesh (11) to form a small-diameter crushed stone layer; Step 303: After all the pores on the surface of the small-diameter crushed stone layer are filled, use a smooth-wheel roller to conduct the fifth compaction until the surface of the small-diameter crushed stone layer is flat and stable, without obvious wheel marks and without the phenomenon of stone creep, to form a flat crushed stone cushion layer.

7. The method according to claim 6, characterized in that: In Step 102, the large-diameter crushed stones (6) are graded crushed stones with a particle size of 2 cm to 4 cm, and the small-diameter crushed stones (7) are graded crushed stones with a particle size of 0.5 cm to 2 cm.

8. The method according to claim 6, characterized in that: In Step 103, the structural dimensions of the first pre-buried positioning mechanism and the second pre-buried positioning mechanism are the same; The first pre-buried positioning mechanism includes a plurality of pre-buried positioning parts (14) arranged along the edge of the large-hole iron mesh (10).

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