CN111979983A

CN111979983A - Sand geological water retaining dam solidified by using construction waste

Info

Publication number: CN111979983A
Application number: CN202010969761.3A
Authority: CN
Inventors: 唐巧雪; 其他发明人请求不公开姓名
Original assignee: Ganzhou Jiuchuang Technology Co ltd
Current assignee: Ganzhou Jiuchuang Technology Co ltd
Priority date: 2020-09-15
Filing date: 2020-09-15
Publication date: 2020-11-24

Abstract

A sandy soil geological retaining dam solidified by utilizing construction waste comprises a dam body formed by ramming sandy soil and a cement concrete layer poured on the surface of the dam body, wherein a water seepage prevention structure is arranged between the upstream surface of the cement concrete layer and the dam body, the water seepage prevention structure comprises a first hydration isolation layer close to the upstream surface and a second hydration isolation layer close to the dam body, and a reinforcing filling layer is formed between the first hydration isolation layer and the second hydration isolation layer. The hydration isolation layers of the invention all use building waste as aggregate, and quicklime and cement are mixed, so that a filling layer with higher porosity relative to a middle reinforcing filling layer is formed, and fault isolation with different porosities is formed at the junction of the reinforcing filling layer and the hydration isolation layers, thereby greatly reducing the permeation rate and the permeation quantity of water in the hydration isolation layers; quicklime and cement are selected and combined with water seepage to be condensed and solidified to form a waterproof interlayer with certain strength and density, so that water seepage is prevented, and construction waste is recycled.

Description

Sand geological water retaining dam solidified by using construction waste

Technical Field

The invention relates to the field of recycling of construction waste in solid waste, in particular to a sandy soil geological retaining dam solidified by using construction waste.

Background

The south of the west of a river belongs to a watery and watery area, and the river is generally guided by a water retaining dam in order to guide the trend of a river channel or prevent the river from scouring the change of the flow direction of the river channel in the flood season;

when the water retaining dam is built, the main body of the water retaining dam is generally formed by ramming soil in the environment of the water retaining dam based on the geological conditions of the section, and then pouring cement concrete on the surface of the water retaining dam for reinforcement and water prevention; however, under sandy soil geological conditions, because grains in a sandy soil layer are large, cementation is lacked among the grains, and the permeability coefficient is large, and in addition, the grains are soaked by river water for a long time, water inevitably permeates through cement concrete and gradually permeates into the interior of the dam body, so that the internal strength is reduced, and even the internal water seepage causes damage to the internal structure of the dam body in the freezing and thawing process under extreme weather conditions, and the risk potential is caused.

With the rapid development of urbanization and construction industry in China, the production amount of construction waste is over hundred million tons, the total amount of the construction waste produced in 2013 in China reaches about 10 million tons, the number is increased year by year, the utilization rate of converting the construction waste into renewable resources is only 5 percent, a large amount of construction waste is abandoned, a large amount of land is occupied, and resource waste is also caused.

Disclosure of Invention

In order to solve the problems of low utilization rate of the existing construction waste and serious water seepage caused by high porosity of the retaining dam under the sandy soil geological condition, the invention provides the sandy soil geological retaining dam solidified by utilizing the construction waste.

The technical scheme adopted by the invention for solving the technical problems is as follows: a sandy soil geological retaining dam solidified by utilizing construction waste comprises a dam body formed by ramming sandy soil and a cement concrete layer poured on the surface of the dam body, wherein a water seepage prevention structure is arranged between the upstream surface of the cement concrete layer and the dam body, the water seepage prevention structure comprises a first hydration isolation layer close to the upstream surface and a second hydration isolation layer close to the dam body, and a reinforced filling layer is formed between the first hydration isolation layer and the second hydration isolation layer, wherein the first hydration isolation layer is formed by ramming medium-particle construction waste, quicklime, cement and sandy soil with the particle size of 10-20mm after being mixed according to the mass ratio of 2:1:3:4, the second hydration isolation layer is formed by ramming coarse-particle construction waste, steel slag powder, quicklime and cement with the particle size of 25-35mm after being mixed according to the mass ratio of 3:2:1:4, and the reinforced filling layer is formed by ramming fine-particle construction waste with the particle size of no more than 10mm, The steel slag powder and the cement are mixed according to the mass ratio of 2:3:5 and then are rammed.

As an optimized scheme of the water retaining dam, the thickness of the first hydration isolation layer is 20-30cm, the thickness of the second hydration isolation layer is 10-30cm, and the thickness of the reinforced filling layer is 30-50 cm.

As another optimization scheme of the retaining dam, at least two impervious walls parallel to the upstream surface of the dam body are arranged in the dam body, and the construction steps of the impervious walls are as follows:

1) drawing a width boundary of the impervious wall on the rammed dam body along the planned length direction of the impervious wall so as to form two parallel preset lines;

2) digging grooves with the width of 5-10cm along two parallel preset lines to form a first preset groove and a second preset groove, wherein the depth of the two grooves is the height of the impervious wall, and the distance between the two grooves is the thickness of the impervious wall;

3) a plurality of supporting pipe fittings A are arranged in the first preset groove along the length direction of the first preset groove, and the bottoms and the tops of the supporting pipe fittings A are flush with the bottom and the top of the first preset groove;

the supporting pipe fitting A is an arc-shaped pipe or a [ -shaped pipe with an opening facing one side of the second preset groove, and the opening side of the supporting pipe fitting A tightly props against the side wall of the first preset groove, so that a grouting channel is formed by the supporting pipe fitting A and the side wall of the first preset groove;

4) arranging a reinforcement cage at a position between the support pipe fittings A in the first preset groove, pouring cement concrete, and forming a boundary wall body A with a plurality of grouting channels in the middle after the cement concrete is solidified;

5) a plurality of supporting pipe fittings B are arranged in the second preset groove along the length direction of the second preset groove, the bottoms and the tops of the supporting pipe fittings B are flush with the bottom and the top of the second preset groove, and the tops and the bottoms of the supporting pipe fittings B are open, so that a negative pressure channel is formed in the supporting pipe fittings B;

6) arranging a reinforcement cage at a position between the support pipe fittings B in the second preset groove, pouring cement concrete, and forming a boundary wall body B with a plurality of negative pressure channels in the middle after the cement concrete is solidified;

7) the negative pressure channels in the boundary wall body B correspond to the grouting channels in the boundary wall body A one by one to form a grouting channel group;

8) along the length direction of the boundary wall A and the boundary wall B, a grouting channel group consisting of a grouting channel and a corresponding negative pressure channel is numbered in sequence and is divided into an odd grouting channel group and an even grouting channel group according to the number;

9) according to the marking sequence, two grouting channels of the adjacent odd number grouting channel groups are grouted, during grouting, cement slurry is pumped into the two grouting channels simultaneously, and negative pressure is applied to the top ports of the two negative pressure channels, so that the cement slurry injected into the grouting channels penetrates through sandy soil geology and then enters the negative pressure channels from the bottoms of the negative pressure channels;

10) detecting the water-cement ratio of the grout pumped from the two groups of negative pressure channels, and stopping grouting into the two grouting channels when the water-cement ratio of the grout is stable and unchanged to finish grouting of the two odd grouting channel groups;

11) grouting two grouting channels of adjacent even grouting channel groups according to the marking sequence, simultaneously pumping cement slurry into the two grouting channels during grouting, and applying negative pressure to top ports of the two negative pressure channels so that the cement slurry injected into the grouting channels penetrates through sandy soil geology and then enters the negative pressure channels from the bottoms of the negative pressure channels;

12) detecting the water-cement ratio of the slurry pumped out of the negative pressure channel, and stopping grouting into the two grouting channels when the water-cement ratio of the slurry is stable and unchanged to finish grouting of the two even number grouting channel groups;

13) repeating the steps 9) to 12) until all grouting channel groups complete grouting, namely completing grouting construction of the whole impervious wall;

14) and waiting for 7-10 days to form a complete impervious wall.

the supporting pipe fitting A is a square pipe with two open ends, so that a grouting channel is formed in the supporting pipe fitting A, two opposite side walls of the square pipe are tightly attached to two side walls of the first preset groove, and a pipe body on one side of the supporting pipe fitting A facing the second preset groove is densely provided with through holes with the diameter of 2-5 mm;

14) and waiting for 7-10 days to form a complete impervious wall.

As another optimized scheme of the dam, the distance between two adjacent grouting channels or two adjacent negative pressure channels is 0.5m, and in any grouting channel group, the distance between a grouting channel and a negative pressure channel is 0.8 m; the pressure of pumping the cement paste in the step 9) and the step 11) is 1.5-2.0MPa, and the pressure of applying negative pressure to the port of the negative pressure channel is 1-1.5 MPa.

As another optimized scheme of the water retaining dam, the cement paste used in the grouting in the step 9) and the step 11) is formed by mixing cement, water glass and water, wherein the cement and the water are firstly mixed to form a paste with a water-cement ratio of 0.75-1:1, then the water glass is added into the paste and uniformly stirred, and the adding amount of the water glass is 2-4% of the total mass of the paste; and judging that grouting is finished when the water-cement ratio of the slurry pumped out of the negative pressure channel is stabilized at 0.5: 1.

As another optimization scheme of the retaining dam, the cement paste used in the grouting in the step 9) and the step 11) comprises water, cement, fly ash and water glass, and the mass ratio of the water to the cement paste to the fly ash is 0.75:1:1: 0.3; and judging that grouting is finished when the water-cement ratio of the slurry pumped out of the negative pressure channel is stabilized at 0.5: 1.

The construction waste used in the invention adopts crushed waste masonry and waste concrete.

The mechanism of the water seepage prevention structure mainly embodies the following two aspects:

the first hydration isolation layer of the anti-seepage structure takes medium-particle building rubbish as aggregate, and quicklime, cement and sandy soil are mixed, so that a filling layer with relatively high porosity is formed; the second hydration isolation layer is filled with coarse-grained building waste serving as aggregate and steel slag powder, quicklime and cement serving as powder, so that a filling layer with porosity lower than that of the first hydration isolation layer is formed; the reinforced filling layer between the reinforced filling layer and the reinforced filling layer is formed by mixing fine-particle building garbage, steel slag powder and cement, and the porosity of the reinforced filling layer is obviously smaller than that of the two hydration isolation layers, so that fault isolation with different porosities is formed at the junction of the reinforced filling layer and the hydration isolation layers, and the permeation rate and the permeation quantity of water in the reinforced filling layer and the hydration isolation layers are greatly reduced;

meanwhile, as the first hydration isolation layer and the second hydration isolation layer contain cement and quicklime, the quicklime has moisture absorption performance, after being mixed with the cement, the quicklime can gradually absorb and cure the water permeated in, and after the water seepage exceeds the absorption capacity of the quicklime, the cured lime, the cement, the sand and the construction waste particles can be mixed, condensed and cured to form isolation layers with certain strength and good density; the reinforced filling layer takes cement and steel slag powder as main bodies and can be combined with water seepage, condensed and solidified to form a water-resisting layer with certain strength and density.

The forming mechanism of the impervious wall is as follows:

during the grouting construction, slurry with certain pressure is injected into the grouting channel and is exhausted from one side of the negative pressure channel, the slurry and the negative pressure channel are combined to generate certain guiding force, and the injected cement slurry is filled in gaps of the sandy soil and is gradually solidified to form the impervious wall.

Compared with the prior art, the invention has the following beneficial effects:

1) the construction of the construction waste and the water retaining dam is combined, so that the utilization rate of the construction waste is improved, waste resources are recycled, the water seepage prevention performance and the strength of the water retaining dam are greatly improved, and the service life of the water retaining dam is prolonged;

2) in the first hydration isolation layer of the seepage-proofing structure, medium-particle building rubbish is used as aggregate and is mixed with quicklime, cement and sandy soil, so that a filling layer with relatively high porosity is formed; the second hydration isolation layer is filled with coarse-grained building waste serving as aggregate and steel slag powder, quicklime and cement serving as powder, so that a filling layer with porosity lower than that of the first hydration isolation layer is formed; the reinforced filling layer between the reinforced filling layer and the reinforced filling layer is formed by mixing fine-particle building garbage, steel slag powder and cement, and the porosity of the reinforced filling layer is obviously smaller than that of the two hydration isolation layers, so that fault isolation with different porosities is formed at the junction of the reinforced filling layer and the hydration isolation layers, and the permeation rate and the permeation quantity of water in the reinforced filling layer and the hydration isolation layers are greatly reduced; meanwhile, quicklime and cement are selected from the filling material, and can be combined with water seepage for condensation and solidification to form a waterproof interlayer with certain strength and density, so that water seepage is prevented;

3) the invention utilizes the characteristic of good permeability of sandy soil geology to be matched with a grouting method, and finally forms the impervious wall formed by mixing sandy soil and cement, although the wall strength of the impervious wall is lower than that of a reinforced concrete wall (the strength of the impervious wall is lower than that of the existing cement concrete pouring because the impervious wall is not doped with matrixes such as reinforcing steel bars or broken stones and the like), the construction is simple, the efficiency is high, and the impervious effect is good; during construction, grouting is carried out on one side, negative pressure on the other side is matched with the grouting to form guiding force to guide slurry to form a wall, the guiding wall is formed by solidifying a sandy soil stratum by cement slurry, and the stratum permeability of sandy soil is effectively utilized, so that an underground impervious wall is built under the condition of an undisturbed stratum, the environment is protected, and the strength of the wall can be effectively improved;

4) when the anti-seepage wall is in grouting construction, the grouting channel and the negative pressure channel are matched and guided to form the wall, the grouting channel is small, construction is more convenient during construction, and hole collapse is not easy to occur; because the negative pressure channel has very large negative pressure during construction, in order to prevent hole collapse, the support pipe fitting B is arranged in the negative pressure channel, the negative pressure channel can be stabilized, the wall can be retained in the wall as a framework when the wall is formed, and more importantly, due to the existence of the support pipe fitting B, the horizontal transverse movement of cement paste is cut off, so that the cement paste seeped from the grouting channel gradually moves downwards to an opening at the bottom of the support pipe fitting B in an arc shape in sandy soil, and the uniformity and consistency during wall grouting are greatly improved; the supporting pipe fittings A are used as grouting channels, the supporting pipe fittings B are used as negative pressure channels, reinforcement cages are placed between the supporting pipe fittings A and between the supporting pipe fittings B, cement concrete is further poured to form, and the strength of the impervious wall is improved while the grouting channels and the negative pressure channels are solidified;

5) during grouting construction, the invention adopts a hole-separating grouting method of firstly pouring two adjacent odd grouting channels and then pouring two adjacent even grouting channels, so that the grouting wall-forming efficiency is higher, the quality of a wall body is improved, and due to the hole-separating grouting wall-forming mode, the grouting influence ranges are gradually crossed, the seam is eliminated, and the problem that the seam of the impervious wall is easy to leak water is solved;

6) the water glass is added into the grouting material, so that the fluidity of the slurry is improved, more importantly, after the slurry containing the water glass is mixed with the sandy soil, the consolidation of the sandy soil and the slurry can be realized within a certain time, and the expansion characteristic of cement after meeting water can be utilized to be mixed with the corresponding sandy soil with poor gradation, so that the permeability of the sandy soil is effectively reduced.

Drawings

FIG. 1 is a schematic cross-sectional view of the present invention;

FIG. 2 is a schematic view of one construction scheme of the diaphragm wall;

FIG. 3 is a schematic view of another construction scheme of the impervious wall;

FIG. 4 is a schematic view of a reinforcement cage disposed between support tubes and poured with concrete;

FIG. 5 is a schematic diagram of a guiding wall forming mechanism of the diaphragm wall;

reference numerals: 1. the dam comprises a dam body, 2, a cement concrete layer, 201, a water facing surface, 3, a first hydration isolation layer, 4, a reinforcing filling layer, 5, a second hydration isolation layer, 6, an impervious wall, 601, a first preset groove, 602, a second preset groove, 603, supporting pipe fittings A and 604, supporting pipe fittings B and 605 and a reinforcement cage.

Detailed Description

The technical solution of the present invention is further described in detail with reference to the following specific embodiments. The parts not disclosed in the present invention or the parts not specifically referred to as structures are prior art. For example, the so-called reinforcement cage 605 is actually a three-dimensional reinforcement structure formed by weaving reinforcement bars and functioning as a framework in concrete, and having a certain width, length and height, and is the prior art.

Example 1

As shown in figure 1, the sandy soil geological retaining dam solidified by utilizing construction waste comprises a dam body 1 formed by ramming sandy soil and a cement concrete layer 2 poured on the surface of the dam body, wherein a water seepage prevention structure is arranged between an upstream surface 201 of the cement concrete layer 2 and the dam body 1, the water seepage prevention structure comprises a first hydration isolation layer 3 adjacent to the upstream surface 201 and a second hydration isolation layer 5 adjacent to the dam body 1, and a reinforcing filling layer 4 is formed between the first hydration isolation layer 3 and the second hydration isolation layer 5, wherein the first hydration isolation layer 3 is formed by ramming medium-particle construction waste, quicklime, cement and sandy soil with the particle size of 10-20mm after being mixed according to the mass ratio of 2:1:3:4, the second hydration isolation layer 5 is formed by ramming coarse-particle construction waste, steel slag powder, quicklime and cement with the particle size of 25-35mm after being mixed according to the mass ratio of 3:2:1:4, the reinforced filling layer 4 is formed by ramming after mixing fine-particle building garbage, steel slag powder and cement with the particle size not more than 10mm in a mass ratio of 2:3: 5.

In this embodiment, the sandy soil in the first hydrated isolation layer 3 is sandy soil selected according to local conditions under sandy soil geological conditions.

Example 2

This embodiment is an improved scheme based on embodiment 1, and the main structure thereof is the same as embodiment 1, and the improvement point is that: as shown in fig. 1, the thickness of the first hydration isolation layer 3 is 20-30cm, the thickness of the second hydration isolation layer 5 is 10-30cm, and the thickness of the reinforcing filling layer 4 is 30-50 cm.

Example 3

The present embodiment is another modified scheme based on embodiment 1, and the main structure of the present embodiment is the same as that of embodiment 1, and the improvement point is that: as shown in fig. 2, 4 and 5, at least two impervious walls 6 parallel to the upstream surface 201 of the dam 1 are arranged in the dam 1, and the construction steps of the impervious walls 6 are as follows:

1) drawing a width boundary of the impervious wall on the rammed dam body 1 along the length direction of the planned impervious wall so as to form two parallel preset lines;

2) digging grooves with the width of 5-10cm along two parallel preset lines to form a first preset groove 601 and a second preset groove 602, wherein the depth of the two grooves is the height of the impervious wall, and the distance between the two grooves is the thickness of the impervious wall;

3) a plurality of supporting pipe fittings A603 are arranged in the first preset groove 601 along the length direction of the first preset groove, and the bottoms and the tops of the supporting pipe fittings A603 are flush with the bottom and the top of the first preset groove 601;

the supporting pipe fitting A603 is an arc-shaped pipe or a [ -shaped pipe with an opening facing one side of the second preset groove 602, and the opening side of the supporting pipe fitting A is tightly propped against the side wall of the first preset groove 601, so that a grouting channel is formed by the supporting pipe fitting A603 and the side wall of the first preset groove 601; the [ -shaped pipe is characterized in that the section is [ ", and the [" -shaped pipe is composed of a middle plate and two vertical plates vertically arranged on two sides of the middle plate, and the two vertical plates are both positioned on the same side of the middle plate;

4) arranging a reinforcement cage 605 at a position between the support pipe fittings A603 in the first preset groove 601, pouring cement concrete, and forming a boundary wall body A with a plurality of grouting channels in the middle after the cement concrete is solidified;

5) a plurality of supporting pipe fittings B604 are arranged in the second preset groove 602 along the length direction of the second preset groove, the bottoms and the tops of the supporting pipe fittings B604 are flush with the bottom and the top of the second preset groove 602, and the tops and the bottoms of the supporting pipe fittings B604 are open, so that a negative pressure channel is formed in the supporting pipe fittings B;

6) arranging a reinforcement cage 605 at a position between the support pipe fittings B604 in the second preset groove 602, pouring cement concrete, and forming a boundary wall body B with a plurality of negative pressure channels in the middle after the cement concrete is solidified;

14) and waiting for 7-10 days to form a complete impervious wall.

Example 4

The present embodiment is another modified scheme based on embodiment 1, and the main structure of the present embodiment is the same as that of embodiment 1, and the improvement point is that: as shown in fig. 3, 4 and 5, at least two impervious walls 6 parallel to the upstream surface 201 of the dam 1 are arranged in the dam 1, and the construction steps of the impervious walls 6 are as follows:

the supporting pipe fitting A603 is a square pipe with two open ends, so that a grouting channel is formed in the supporting pipe fitting A603, two opposite side walls of the square pipe are tightly attached to two side walls of the first preset groove 601, and a pipe body facing one side of the second preset groove 602 is densely provided with through holes with the diameter of 2-5 mm;

14) and waiting for 7-10 days to form a complete impervious wall.

Example 5

This embodiment is an improved scheme based on embodiment 4, and the main structure thereof is the same as embodiment 4, and the improvement point is that: the distance between the two adjacent grouting channels or the two adjacent negative pressure channels is 0.5m, and the distance between the grouting channel and the negative pressure channel in any grouting channel group is 0.8 m; the pressure of pumping the cement paste in the step 9) and the step 11) is 1.5-2.0MPa, and the pressure of applying negative pressure to the port of the negative pressure channel is 1-1.5 MPa.

Of course, this embodiment may also be modified based on embodiment 3, and the modification is the same as the modification made on embodiment 4.

Example 6

This embodiment is an improved scheme based on embodiment 4, and the main structure thereof is the same as embodiment 4, and the improvement point is that: the cement paste used in the grouting in the step 9) and the step 11) is formed by mixing cement, water glass and water, wherein the cement and the water are firstly mixed to form a paste with a water-cement ratio of 0.75-1:1, then the water glass is added into the paste and uniformly stirred, and the adding amount of the water glass is 2-4% of the total mass of the paste; and judging that grouting is finished when the water-cement ratio of the slurry pumped out of the negative pressure channel is stabilized at 0.5: 1.

Example 7

This embodiment is an improved scheme based on embodiment 4, and the main structure thereof is the same as embodiment 4, and the improvement point is that: the cement paste used in the grouting in the step 9) and the step 11) comprises water, cement, fly ash and water glass, and the mass ratio of the water to the cement to the fly ash is 0.75:1:1: 0.3; and judging that grouting is finished when the water-cement ratio of the slurry pumped out of the negative pressure channel is stabilized at 0.5: 1.

Claims

1. The utility model provides an utilize sandy soil geology retaining dam of building rubbish solidification, includes dam body (1) that is rammed by the sandy soil and forms and pours cement concrete layer (2) on its surface, its characterized in that: an anti-seepage structure is arranged between the upstream face (201) of the cement concrete layer (2) and the dam body (1), the anti-seepage structure comprises a first hydration isolation layer (3) adjacent to the upstream face (201) and a second hydration isolation layer (5) adjacent to the dam body (1), and a reinforced filling layer (4) is formed between the first hydration isolation layer (3) and the second hydration isolation layer (5), wherein the first hydration isolation layer (3) is formed by mixing and tamping medium-particle building garbage, quicklime, cement and sandy soil with the particle size of 10-20mm according to the mass ratio of 2:1:3:4, the second hydration isolation layer (5) is formed by mixing and tamping coarse-particle building garbage, steel slag powder, quicklime and cement with the particle size of 25-35mm according to the mass ratio of 3:2:1:4, and the reinforced filling layer (4) is formed by mixing and tamping fine-particle building garbage with the particle size of no more than 10mm, The steel slag powder and the cement are mixed according to the mass ratio of 2:3:5 and then are rammed.

2. The sandy soil geological retaining dam solidified by using the construction waste as claimed in claim 1, wherein: the thickness of the first hydration isolation layer (3) is 20-30cm, the thickness of the second hydration isolation layer (5) is 10-30cm, and the thickness of the reinforced filling layer (4) is 30-50 cm.

3. The sandy soil geological retaining dam solidified by using the construction waste as claimed in claim 1, wherein: at least two impervious walls (6) parallel to the upstream face (201) of the dam body (1) are arranged in the dam body (1), and the construction steps of the impervious walls (6) are as follows:

1) drawing a width boundary of the diaphragm wall on the rammed dam body (1) along the length direction of the planned diaphragm wall, thereby forming two parallel preset lines;

2) digging grooves with the width of 5-10cm along two parallel preset lines to form a first preset groove (601) and a second preset groove (602), wherein the depth of the two grooves is the height of the impervious wall, and the distance between the two grooves is the thickness of the impervious wall;

3) a plurality of supporting pipe fittings A (603) are arranged in the first preset groove (601) along the length direction of the first preset groove, and the bottoms and the tops of the supporting pipe fittings A (603) are flush with the bottom and the top of the first preset groove (601);

the supporting pipe fitting A (603) is an arc-shaped pipe or a [ -shaped pipe with an opening facing one side of the second preset groove (602), and the opening side of the supporting pipe fitting A tightly props against the side wall of the first preset groove (601), so that a grouting channel is defined by the supporting pipe fitting A and the side wall of the first preset groove (601);

4) arranging a reinforcement cage (605) at a position between the support pipe fittings A (603) in the first preset groove (601), pouring cement concrete, and forming a boundary wall body A with a plurality of grouting channels in the middle after the cement concrete is solidified;

5) a plurality of supporting pipe fittings B (604) are arranged in the second preset groove (602) along the length direction of the second preset groove, the bottoms and the tops of the supporting pipe fittings B (604) are flush with the bottom and the top of the second preset groove (602), and the tops and the bottoms of the supporting pipe fittings B (604) are open, so that a negative pressure channel is formed in the supporting pipe fittings B;

6) arranging a reinforcement cage (605) at a position between the support pipe fittings B (604) in the second preset groove (602), pouring cement concrete, and forming a boundary wall body B with a plurality of negative pressure channels in the middle after the cement concrete is solidified;

14) and waiting for 7-10 days to form a complete impervious wall.

4. The sandy soil geological retaining dam solidified by using the construction waste as claimed in claim 1, wherein: at least two impervious walls (6) parallel to the upstream face (201) of the dam body (1) are arranged in the dam body (1), and the construction steps of the impervious walls (6) are as follows:

the supporting pipe fitting A (603) is a square pipe with two open ends, so that a grouting channel is formed in the supporting pipe fitting A, two opposite side walls of the square pipe are tightly attached to two side walls of the first preset groove (601), and a pipe body of one side of the supporting pipe fitting A facing the second preset groove (602) is densely provided with through holes with the diameter of 2-5 mm;

14) and waiting for 7-10 days to form a complete impervious wall.

5. The sandy soil geological barrage solidified by using the construction waste as claimed in claim 3 or 4, wherein: the distance between the two adjacent grouting channels or the two adjacent negative pressure channels is 0.5m, and the distance between the grouting channel and the negative pressure channel in any grouting channel group is 0.8 m; the pressure of pumping the cement paste in the step 9) and the step 11) is 1.5-2.0MPa, and the pressure of applying negative pressure to the port of the negative pressure channel is 1-1.5 MPa.

6. The sandy soil geological barrage solidified by using the construction waste as claimed in claim 3 or 4, wherein: the cement paste used in the grouting in the step 9) and the step 11) is formed by mixing cement, water glass and water, wherein the cement and the water are firstly mixed to form a paste with a water-cement ratio of 0.75-1:1, then the water glass is added into the paste and uniformly stirred, and the adding amount of the water glass is 2-4% of the total mass of the paste; and judging that grouting is finished when the water-cement ratio of the slurry pumped out of the negative pressure channel is stabilized at 0.5: 1.

7. The sandy soil geological barrage solidified by using the construction waste as claimed in claim 3 or 4, wherein: the cement paste used in the grouting in the step 9) and the step 11) comprises water, cement, fly ash and water glass, and the mass ratio of the water to the cement to the fly ash is 0.75:1:1: 0.3; and judging that grouting is finished when the water-cement ratio of the slurry pumped out of the negative pressure channel is stabilized at 0.5: 1.