CN112593579A

CN112593579A - Karst mountain land clay-doped clay purified sewage anti-seepage soft pit and construction method thereof

Info

Publication number: CN112593579A
Application number: CN202011485387.6A
Authority: CN
Inventors: 彭韬; 包海梅; 冯伟; 罗林; 戴德求
Original assignee: Institute of Geochemistry of CAS
Current assignee: Institute of Geochemistry of CAS
Priority date: 2020-12-16
Filing date: 2020-12-16
Publication date: 2021-04-02
Also published as: NL2028968B1; NL2028968A

Abstract

The invention discloses a karst mountain land clay-doped clay sewage purification anti-seepage soft pit and a construction method thereof. The mud-doped clay purified sewage seepage-prevention soft pit in the male karst mountain region comprises a soil pit and a clay layer laid at the bottom of the soil pit, wherein the clay layer is provided with the mud-doped clay layer, and the mud-doped clay layer is provided with a water purification layer. The construction method of the karst mountain land mud-doped clay sewage purification anti-seepage soft pit comprises the following steps: A. paving clay on the soil pit 1, and injecting water, stirring, compacting and leveling to obtain a clay layer 2; B. paving clay-doped clay on the clay layer 2 to obtain a clay-doped clay layer 3; C. uniformly scattering water purification substances at the bottom of the clay-doped layer 3 to obtain a water purification layer 4; D. sowing grass seeds on the side slope of the clay-doped layer 2. The invention has the advantages of good anti-seepage effect and capability of performing sewage treatment and slope nursing.

Description

Karst mountain land clay-doped clay purified sewage anti-seepage soft pit and construction method thereof

Technical Field

The invention relates to the technical field of seepage-proofing structures, in particular to a karst mountain land clay-doped clay sewage purification seepage-proofing soft pit and a construction method thereof.

Background

In karst regions, as underground karst cracks develop seriously, untreated rural domestic sewage permeates underground water through the cracks or seeps into surface rivers to cause river or underground water pollution and worsen the quality of drinking water of local residents and even downstream residents. The occurrence of the phenomenon is not prevented, and a plurality of anti-seepage structures are built in the karst region.

The traditional anti-seepage plugging technology such as concrete anti-seepage wall and split curtain grouting has small construction depth and poor stratum adaptability; some of the technologies need to adopt large-scale or heavy equipment, are expensive and have the problem that the leakage position is difficult to enter.

Therefore, finding an effective, economical and environment-friendly anti-seepage method becomes one of the hot spots in the research of the karst region domestic sewage treatment field.

Disclosure of Invention

The invention aims to provide a karst mountain land clay-doped clay sewage purification anti-seepage soft pit and a construction method thereof. The invention has the advantages of good anti-seepage effect and capability of performing sewage treatment and slope nursing.

The technical scheme of the invention is as follows: a karst mountain land clay-doped clay sewage purification seepage-proofing soft pit comprises a soil pit and a clay layer laid at the bottom of the soil pit, wherein a clay-doped clay layer is arranged on the clay layer, and a water purification layer is arranged on the clay-doped clay layer.

In the karst mountain land clay-doped clay sewage purification anti-seepage soft pit, grass seeds are arranged on the side slope of the clay-doped clay layer.

In the karst mountain land clay-doped clay sewage purification anti-seepage soft pit, the thickness of the clay layer is 500-1000 mm; the thickness of the clay-doped clay layer is 500-1000 mm; the thickness of the water purification layer is 3-20 mm.

In the karst mountain land mud-doped clay sewage purification anti-seepage soft pit, the water purification material of the water purification layer is (25-35): (50-60) the aluminum sulfate and the stone powder are mixed to prepare particles, and the particle size is 2-3 mm.

In the karst mountain region mud-doped clay sewage purification anti-seepage soft pit, the water purification material of the water purification layer is 6: 11, the aluminum sulfate and the stone powder are mixed to prepare particles with the particle size of 2-3 mm.

In the karst mountain land clay-doped clay purified sewage anti-seepage soft pit, the clay-doped clay layer is prepared from the following materials in mass ratio of (5-15): (85-95) a mixture of clay and bottom mud.

In the karst mountain land clay-doped clay sewage purification anti-seepage soft pit, the material content of the clay-doped clay layer 4 is 70-80%, the material content of fine sand is 10-20%, and the particle size is less than or equal to 0.04 mm.

In the karst mountain land clay-doped clay sewage purification anti-seepage soft pit, the material of the clay-doped clay layer 4 contains 75% of powder particles, 15% of fine sand particles and has a particle size of less than or equal to 0.04 mm.

The construction method for purifying the sewage anti-seepage soft pit by the mud-doped clay in the karst mountain land comprises the following steps:

A. paving clay on the soil pit, and injecting water, stirring, compacting and leveling to obtain a clay layer;

B. paving clay doped clay on the clay layer to obtain a clay doped clay layer;

C. uniformly scattering water purification substances at the bottom of the clay layer doped with the mud to obtain a water purification layer;

D. sowing grass seeds on the side slope of the clay layer doped with the mud.

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

according to the invention, the bed mud and the clay are fully mixed, the saturated hydraulic conductivity of the soil is reduced, the anti-seepage effect is achieved, abundant microbial resources in the farmland bed mud generate a large amount of extracellular secretion under the excitation of nutrient substances, the plugging effect is finally achieved, and meanwhile, the passivation zone is formed by combining with aluminum sulfate and stone powder, so that not only are nutrient salts in a water body adsorbed, but also a passivation layer is formed on the surface of the sediment, the endogenous release amount of nutrient salts is remarkably reduced, the sediment-water interface in the passivation zone is in an oxygen-rich state, and the release amount of the endogenous nutrient salts is reduced. Along with the gradual improvement of the water quality of the passivation area, the gradually recovered submerged plants can also slow down wind waves and fix bottom mud, the self-purification effect of the water body is greatly enhanced, and the accumulation of ammonia nitrogen and phosphorus of the water body is reduced, so that the content of nutrient salts of the water body of the passivation area is obviously lower than that of a control area, a passivation layer is formed on the surface layer of a sediment, and the supply of nutrient substances to an overlying water body is reduced through the effects of surface adsorption, ion exchange, physical barrier and the like, so that the aim of controlling the eutrophication of the water body is fulfilled, and finally, an anti-. Meanwhile, the seepage-proofing effect of the seepage-proofing soft pit can reach the level of micro water permeability.

Drawings

Fig. 1 is a schematic structural view of the present invention.

The labels in the figures are: 1-soil pit, 2-clay layer, 3-clay-doped clay layer, 4-water purification layer, 5-grass and 6-domestic sewage.

Detailed Description

The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.

Examples are given. A karst mountain region is mixed mud clay and is purified sewage prevention of seepage soft hole, constitutes as shown in figure 1, including soil pit 1 with lay in clay layer 2 of soil pit 1 bottom, is equipped with on clay layer 2 and mixes mud clay layer 3, is equipped with water purification layer 4 on the pit of mixing mud clay layer 3. The soil pit 1 refers to a natural soil pit of the karst mountain land.

Grass seeds are arranged on the side slope of the soil-mixed clay layer 3. The grass seeds are integrated with the surrounding environment after growing into grass, and the effect of preventing rain wash and achieving slope nursing is achieved.

The thickness of the clay layer 2 is 500-1000 mm; the thickness of the clay-doped clay layer 3 is 500-1000 mm; the thickness of the water purification layer 4 is 3-20 mm. The thickness design is that after the saturated hydraulic conductivity is measured by cutting-ring soil sampling, the thickness of 500mm is the minimum impermeable thickness of the clay layer 2 and the clay-doped clay layer 3.

The water purifying material of the water purifying layer 4 is 25-35 by mass: 50-60 of aluminum sulfate and stone powder are mixed to prepare spherical particles with the particle size of 2-3 mm. According to experiments, the mass ratio of the aluminum sulfate to the stone powder is preferably 6: 11 is to NH^3-N and TP have better removal effect.

The clay-doped clay layer 3 is prepared from the following materials in percentage by mass (5-15): (85-95) a mixture of clay and bottom mud. The sediment refers to farmland sediment. The mass ratio of the clay and the bottom mud with good seepage-proofing effect is preferably 1:9, namely, the clay accounts for 10% and the farmland bottom mud accounts for 90% in the clay-doped clay. So specified is according to the international soil preparation grading standard: the grain size of the clay is 0.0001-0.002mm, and the grain size result shows that the grain size is less than 0.0027mm (clay) accounting for 10% after the clay-doped clay with good anti-seepage effect is analyzed and measured.

The material of the clay-doped clay layer 3 comprises 70-80% of powder particles, 10-20% of fine sand particles and the particle size of less than or equal to 0.04 mm. According to the international soil preparation grading standard: gravel: 3-2; coarse sand grain: 0.2-2 mm; fine sand grains: 0.02-0.2 mm; powder particle: 0.002-0.02 mm; sticky particles: 0.0001-0.002 mm. Actually measured, the silt of the clay-doped clay with good seepage-proofing effect accounts for 75 percent, the fine sand accounts for 15 percent, the minimum particle size is 0.003mm, the maximum particle size is 0.04mm, the maximum water holding capacity is 67.98 percent, the capillary water holding capacity is 64.61 percent, and the soil volume weight is 0.91 g-cm^-3The porosity of non-capillary is 3.08%, the porosity of capillary is 58.92%, the total porosity is 62.00%, and the saturated hydraulic conductivity of soil is 3.64 multiplied by 10^-6cm/s。

A construction method for purifying sewage and preventing seepage of soft pits by using clay doped in karst mountainous regions comprises the following steps:

A. paving clay on the soil pit 1, and performing water injection stirring, layering compaction and man-machine leveling to obtain a clay layer 2; the clay is mixed with a proper amount of water to form a mud cluster, the mud cluster deforms but does not crack under the action of external force, the original shape can still be kept unchanged after the external force is dissipated, and the clay is combined with a non-plastic raw material to form a good plastic mud cluster and has certain drying strength; controlling the water injection amount based on the fact that water injection reaches a clay saturation state;

B. paving clay-doped clay on the clay layer 2 to obtain a clay-doped clay layer 3;

C. uniformly scattering water purification substances at the bottom of the clay-doped layer 3 to obtain a water purification layer 4;

D. sowing grass seeds on the side slope of the clay-doped layer 2.

According to the invention, the bottom of the soil pit 1 is tamped through the clay layer 2, farmland bottom mud is doped into clay and fully mixed, abundant microbial resources in the farmland bottom mud are utilized, a large amount of extracellular secretion is generated under the excitation of nutrient substances, the saturated hydraulic conductivity of the soil is reduced, and finally the plugging and seepage-proofing effects are achieved.

Examples of the experiments. A large number of experiments are carried out in the research process of the invention, and part of the experiments are recorded and analyzed as follows:

and (5) inspecting the related performance of the clay doped with the mud. The saturated hydraulic conductivity of the soil is the water quantity passing through a unit area in unit time under a unit water potential gradient when the soil is saturated by water, and is a function of the soil texture, the volume weight and the pore distribution characteristics, the saturated hydraulic conductivity has strong spatial variation due to the influence of spatial variables such as the soil texture, the volume weight, the pore distribution, the organic matter content and the like, and the pore distribution characteristics have the greatest influence on the saturated hydraulic conductivity of the soil. The saturated water conductivity of soil is one of important physical properties of soil, is an important soil parameter for calculating the water flux in a soil profile and designing irrigation and drainage system engineering, is also an important parameter in a hydrological model, and seriously influences the precision of the model if the soil is accurate or not.

After the karst mountain region mud-doped clay sewage purification seepage-proofing soft pit is completed, a KSAT soil saturated hydraulic conductivity measuring instrument is used for testing the mud-doped clay saturated hydraulic conductivity.

The measurement principle is as follows: under the condition of room temperature, the cross section of a completely saturated clay-doped clay sample is vertically acted by using the demineralized water, and the flow velocity and the driving hydraulic gradient are measured. The clay-doped clay and the water conductivity (KS) are calculated by dividing the volumetric water flow by the cross-sectional area and time of the soil, the length of a clay-doped clay sample and the water head gradient along the water flow direction.

The data are as follows:

Ks(Soil)＝3.64×10^-8m/s

the micro water permeability grade in the permeability classification of rock and soil bodies reaches the appendix of geological survey specifications of hydraulic and hydro-power engineering, and the micro water permeability grade shown in the following table 1 shows that the clay-doped clay provided by the invention has a good anti-seepage effect and reaches the highest micro water permeability grade. The corresponding seepage-proofing effect of the seepage-proofing soft pit is also good.

TABLE 1

In addition, the related parameters of the clay doped with the mud are tested. The following are recorded:

and (3) measuring the porosity of the soil:

the soil porosity index is measured by a cutting ring method: firstly, removing an upper cover of a cutting ring filled with clay doped with mud, laying a layer of filter paper on one side with holes, putting the cutting ring into a flat-bottomed container, and then injecting water slightly lower than the cutting edge of the cutting ring into the container to ensure that the cutting ring fully absorbs water for more than 12 hours and immediately weighs: the weighed side of the ring knife with the porous pad filter paper was placed in a tray filled with dry quartz sand for 2h and weighed immediately.

Raw data: after the soil is soaked for 12 hours, the weight of the cutting ring and the wet soil is 585.6g

After the dry sand is placed for 2 hours, the weight of the cutting ring and the wet soil is 577.9g

After the dry sand is placed for 12 hours, the weight of the cutting ring and the wet soil is 571.8g

The weight of the cutting ring and the dry soil is 430.5g

The dry soil in the cutting ring weighs 227.9g

Volume weight of clay doped:

and (3) measuring the bulk density of the soil with cracks by drying the clay doped by the cutting ring, and putting the cutting ring filled with the clay doped into a constant temperature box at 105 ℃ to constant weight.

Volume weight (g cm) of clay doped with mud^-3) The weight of dry soil in the cutting ring/the volume of the cutting ring is 0.91g cm^-3

The non-capillary porosity (%) is 3.08% by volume weight of clay-doped clay (maximum water holding capacity-capillary water holding capacity) × 58.93% by volume weight of capillary pores (capillary water holding capacity) × clay-doped clay)

Total porosity (%)% of non-capillary voids + capillary voids of 62.00%

This shows that the clay-doped clay has good anti-seepage effect, and the corresponding clay-doped clay layer also has good anti-seepage effect.

Claims

1. The utility model provides a karst mountain region is mixed mud clay and is purified soft hole of prevention of seepage of sewage, includes soil pit (1), its characterized in that: the soil pit comprises a clay layer (2) laid at the bottom of a soil pit (1), wherein a mud-doped clay layer (3) is arranged on the clay layer (2), and a water purification layer (4) is arranged on the mud-doped clay layer (3).

2. The karst mountain land mud-doped clay sewage purification seepage-proofing soft pit as claimed in claim 1, which is characterized in that: grass seeds are arranged on the side slope of the mud-doped clay layer (3).

3. The karst mountain land mud-doped clay sewage purification seepage-proofing soft pit as claimed in claim 1, which is characterized in that: the thickness of the clay layer (2) is 500-1000 mm; the thickness of the clay-doped layer (3) is 500-1000 mm; the thickness of the water purification layer (4) is 3-20 mm.

4. The karst mountain land mud-doped clay sewage purification seepage-proofing soft pit as claimed in claim 1, which is characterized in that: the water purifying materials of the water purifying layer (4) are (25-35) by mass: (50-60) the aluminum sulfate and the stone powder are mixed to prepare particles, and the particle size is 2-3 mm.

5. The karst mountain land mud-doped clay sewage purification seepage-proofing soft pit as claimed in claim 1, which is characterized in that: the clay-doped clay layer (3) is prepared from the following materials in percentage by mass (5-15): (85-95) a mixture of clay and bottom mud.

6. The karst mountain land muddy clay purified sewage seepage-proofing soft pit as claimed in claim 5, characterized in that: the material of the clay-doped clay layer (3) comprises 70-80% of powder particles, 10-20% of sand particles and the particle size of less than or equal to 0.04 mm.

7. The construction method for purifying the sewage seepage-proofing soft pit by the mud-doped clay in the karst mountain areas as claimed in any one of claims 1 to 6 comprises the following steps:

A. paving clay on the soil pit (1), and injecting water, stirring, compacting and leveling to obtain a clay layer (2);

B. paving clay-doped clay on the clay layer (2) to obtain a clay-doped clay layer (3);

C. uniformly scattering water purification substances at the bottom of the clay-doped layer (3) to obtain a water purification layer (4);

D. sowing grass seeds on the side slope of the clay-doped layer (2).