Three-dimensional netted drainage salt control and alkali discharge method and system

Abstract

A three-dimensional network drainage salt control and alkali discharge method and system, the method comprising the following steps: laying a soil improvement salt control and alkali discharge channel in a subsoil layer of the saline-alkali soil to be improved for discharging saline-alkali water in the topsoil layer and the subsoil layer from the soil body; laying a hidden passage salt control and alkali discharge channel in a bottom soil layer of the saline-alkali soil to be improved for discharging saline-alkali water below the subsoil layer and discharging the upward saline-alkali water when the saline-alkali water upwardly returns below the bottom soil layer; and drilling a vertical shaft salt control and alkali discharge channel in a micro-domain alkali spot area of the saline-alkali soil to be improved for opening a water-permeable alkali discharge channel from the topsoil layer, the subsoil layer to the bottom soil layer. The invention also provides a three-dimensional network drainage salt control and alkali discharge system constructed by using the above method. The invention improves the number of drainage channels, improves the drainage efficiency, prolongs the service life, reduces the construction cost, and solves the problem of difficulty in discharging salt in the micro-domain hard alkali spot block area where the saline-alkali water upwardly returns.

Description

TECHNICAL FIELD

[0001] The present application relates to saline-alkali soil treatment technology, in particular to a three-dimensional network drainage salt control and alkali discharge method and system for engineering treatment of moderate to severe soda saline-alkali soil. BACKGROUND

[0002] The saline-alkali soil has high salt content, high alkalization degree and high pH, which leads to the intensification of the salinization trend of cultivated land. It is of great significance to carry out comprehensive reconstruction and utilization of moderate to severe soda saline-alkali soil, to fully tap the comprehensive utilization potential of saline-alkali soil, to strengthen the reconstruction and improvement of existing saline-alkali cultivated land, to effectively curb the salinization trend of cultivated land, to steadily expand the agricultural production space, and to improve the comprehensive agricultural production capacity. At present, there is no mature method for engineering treatment of moderate to severe soda saline-alkali soil. The existing technology uses single-layer underground pipe to discharge salt, and the underground pipe is laid below the soil bottom layer. The treatment effect is not ideal for soda saline-alkali soil with heavy texture and poor water permeability, and cannot effectively solve the problem of salt and alkali returning. Moreover, in the micro-domain hard alkali patch area, it is difficult to discharge salt and alkali in the hard saline-alkali soil body where water does not flow. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a three-dimensional network drainage salt control and alkali discharge method and system to solve the above-mentioned defects of the prior art.

[0004] In order to achieve the above-mentioned purpose, the present application provides a three-dimensional network drainage salt control and alkali discharge method, which comprises the following steps:

[0005] S100, laying a soil improvement salt control and alkali discharge channel in the subsoil layer of the saline-alkali soil to be improved, the top of the soil improvement salt control and alkali discharge channel extending into the topsoil layer for discharging saline-alkali water from the topsoil layer and the subsoil layer;

[0006] S200, laying a dark passage salt control and alkali discharge channel in the bottom soil layer of the saline-alkali soil to be improved for discharging saline-alkali water below the subsoil layer and discharging the returned saline-alkali water when the saline-alkali water returns below the bottom soil layer; and

[0007] S300, drilling a vertical shaft salt control and alkali discharge channel in the micro-domain alkali patch area of the saline-alkali soil to be improved for opening the water permeable alkali discharge channel from the topsoil layer, the subsoil layer to the bottom soil layer.

[0008] The three-dimensional network drainage salt control and alkali discharge method described above, wherein the soil improvement salt control and alkali discharge channel constructs a water permeable alkali discharge channel of the subsoil layer by embedding soil improvement filter material in the subsoil layer, and the laying depth of the soil improvement filter material is not less than the depth of the subsoil layer.

[0009] In the above-mentioned three-dimensional mesh drainage method for controlling salt and alkali, the underground channel for controlling salt and alkali is constructed by soil-improving filter material buried in the subsoil layer to form a permeable channel for alkali removal in the subsoil layer, and the burial depth of the underground channel for controlling salt and alkali is 40-60cm.

[0010] In the aforementioned three-dimensional mesh drainage method for controlling salt and alkali removal, the spacing between adjacent underground channels is L, the soil permeability coefficient is K, and the burial depth of the underground channels is h. d The soil empirical coefficient is N, and the distance L between adjacent tunnels satisfies the following relationship: L = NKh d .

[0011] In the above-mentioned three-dimensional mesh drainage method for controlling salt and alkali, the vertical shaft salt and alkali control channel is opened through the vertical shaft filter material filled in the vertical shaft, which opens up the permeable alkali discharge channel from the topsoil layer, subsoil layer to the bottom soil layer, and the depth of the vertical shaft is 60-100cm.

[0012] In the above-mentioned three-dimensional mesh drainage method for controlling salt and alkali, the vertical well salt control and alkali discharge channels are positioned and the number of vertical wells n is set according to the location and area S of the micro-area alkali spot zone. The radiation area of ​​a single well is 10㎡, and the following relationship is satisfied: n=S / 10.

[0013] In the above-mentioned three-dimensional mesh drainage method for controlling salt and alkali, in moderately saline-alkali soil areas, the depth of the vertical shaft is 60cm and it is connected to the underground channel for controlling salt and alkali; in severely saline-alkali soil areas, the depth of the vertical shaft is 80-100cm and it is connected to the underground channel for controlling salt and alkali.

[0014] In the above-mentioned three-dimensional mesh drainage method for controlling salt and alkali, the diameter of the vertical shaft is 10cm.

[0015] The above-mentioned three-dimensional network drainage method for controlling salt and alkali removal includes laying multiple soil improvement channels for controlling salt and alkali removal in parallel horizontally in the subsoil layer; laying multiple underground channels for controlling salt and alkali removal in parallel vertically in the subsoil layer; and drilling multiple vertical well channels for controlling salt and alkali removal in the micro-alkaline spot area to form a three-dimensional network drainage system for controlling salt and alkali removal.

[0016] To better achieve the above objectives, the present invention also provides a three-dimensional mesh drainage system for controlling salt and alkali using the above-described three-dimensional mesh drainage method.

[0017] The technical effects of this invention are as follows:

[0018] This invention constructs a stable water conveyance and salt drainage channel connecting the topsoil and subsoil layers by horizontally burying soil-improving filter material in the subsoil layer, longitudinally laying underground channels and filling them with filter material, and vertically drilling wells in micro-area alkaline patches and filling them with filter material. This inhibits the upward return of salt and alkali from the subsoil, achieving the goal of comprehensive salt and alkali control across the entire soil layer. Simultaneously, it connects with traditional underground pipes to form a complete three-dimensional network drainage and salt control system, increasing the number of drainage channels, improving drainage efficiency, extending service life, and reducing construction costs. It solves the problem of difficult salt drainage in micro-area hard alkaline patches caused by salt and alkali return, providing technical support for the treatment of moderate to severe saline-alkali soils.

[0019] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a three-dimensional mesh drainage salt control and alkali removal system according to an embodiment of the present invention;

[0021] Figure 2 This is a cross-sectional view of a three-dimensional mesh drainage salt control and alkali removal system according to an embodiment of the present invention;

[0022] Figure 3 This is a top view of a three-dimensional mesh drainage salt control and alkali removal system according to an embodiment of the present invention;

[0023] Figure 4 This is a plan view of an embodiment of the present invention.

[0024] Among them, the attached figures are labeled

[0025] 1. Improve the soil control and alkali drainage channel

[0026] 2. Dark channel for salt control and alkali discharge

[0027] 3 vertical shafts for salt control and alkali discharge

[0028] 4 Concealed Pipe Channel

[0029] 5. Saline-alkali soil surface

[0030] 6 core soil layers

[0031] 7. Subsoil layer

[0032] 8 Topsoil layer

[0033] 9 micro-area alkaline spot regions

[0034] 10 Drainage Ditch Detailed Implementation

[0035] The structural and working principles of the present invention will be described in detail below with reference to the accompanying drawings:

[0036] In the description of the embodiments of the present application, it should be understood that the terms "longitudinal", "transverse", "diameter", "depth", "upper", "lower", "vertical", "horizontal", "parallel", "matrix" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the structure or device referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0037] Referring to Figures 1-3 , Figure 1 is a structural schematic diagram of a three-dimensional reticular drainage and salt control and alkali discharge system according to an embodiment of the present application, Figure 2 is a sectional view of a three-dimensional reticular drainage and salt control and alkali discharge system according to an embodiment of the present application, Figure 3 is a top view of a three-dimensional reticular drainage and salt control and alkali discharge system according to an embodiment of the present application. The three-dimensional reticular drainage and salt control and alkali discharge system according to the present application comprises: a soil improvement and salt control and alkali discharge channel 1, which is laid in a subsoil layer 6 of the saline-alkali soil to be improved, and the top of the soil improvement and salt control and alkali discharge channel 1 extends into a topsoil layer 8 to discharge saline-alkali water in the topsoil layer 8 and the subsoil layer 6 from the soil body; a tunnel salt control and alkali discharge channel 2, which is laid in a bottom soil layer 7 of the saline-alkali soil to be improved, and is used to discharge saline-alkali water below the subsoil layer 6 and to discharge the saline-alkali water returned from above the bottom soil layer 7; and a vertical shaft salt control and alkali discharge channel 3, which is drilled in a micro-domain alkali spot area 9 of the saline-alkali soil to be improved, and is used to punch through the water-permeable alkali discharge channels from the topsoil layer 8, the subsoil layer 6 to the bottom soil layer 7, and each water-permeable alkali discharge channel is communicated with a drainage ditch 10 or a water collecting pipe. A plurality of the soil improvement and salt control and alkali discharge channels 1 are laid transversely and in parallel in the subsoil layer 6 with the saline-alkali soil surface 5 as a reference; a plurality of the tunnel salt control and alkali discharge channels 2 are laid longitudinally and in parallel in the bottom soil layer 7; and a plurality of the vertical shaft salt control and alkali discharge channels 3 are drilled vertically in the micro-domain alkali spot area 9 to form a three-dimensional reticular drainage and salt control and alkali discharge channel.

[0038] In some embodiments, the soil improvement and salt control and alkali discharge channel 1 of the subsoil layer 6 can comprise a plurality of soil improvement filter materials laid transversely and in parallel, and the tunnel salt control and alkali discharge channel 2 of the bottom soil layer 7 can comprise a plurality of tunnel filter materials laid longitudinally and in parallel. Specifically, the plurality of soil improvement and salt control and alkali discharge channels 1 and the plurality of tunnel salt control and alkali discharge channels 2 are distributed in the subsoil layer 6 and the bottom soil layer 7 respectively, which can not only save resources but also ensure good salt and water discharge effect. The soil improvement and salt control and alkali discharge channel 1 constructs the water-permeable alkali discharge channel of the subsoil layer 6 through the soil improvement filter material buried in the subsoil layer 6, and the laying depth of the soil improvement filter material is not less than the depth of the subsoil layer 6.

[0039] In some embodiments, the tunnel buried depth is defined as h d , the salt discharge depth is defined as h, the water depth in the tunnel or the diameter of the tunnel is defined as r, and the tunnel buried depth is defined as h dsatisfies the following relationship: h d = h + r. Wherein, h d — the depth of the buried conduit, unit: m; h— the depth of the salt discharge or the critical depth, unit: m; r— the water depth in the buried conduit, which can be replaced by the diameter of the buried conduit, unit: m. The depth, location and soil profile sampling data of the existing buried conduit can be obtained through the actual construction data before the investigation. Specifically, due to the limitation of economic and technical conditions, it is not convenient to analyze the saline-alkali soil layer in the improvement, so the above standard can be used to simplify the planning and design process. Specifically, the buried depth of the buried conduit can also seek the best buried depth suitable for local economic and technical conditions, which should be selected according to the local conditions after comprehensive demonstration.

[0040] The buried conduit salt control and alkali discharge channel 2 constructs the permeable alkali discharge channel of the bottom soil layer 7 through the buried conduit filter material buried in the bottom soil layer 7, and the buried depth of the buried conduit salt control and alkali discharge channel 2 is preferably 40-60 cm. The adjacent buried conduit spacing of the buried conduit salt control and alkali discharge channel 2 is L, the soil permeability coefficient is K, the buried depth of the buried conduit is h d , the soil empirical coefficient is N, and the adjacent buried conduit spacing L satisfies the following relationship: L = NKh d . Wherein, L— the buried conduit spacing, unit: m; K— the soil permeability coefficient, unit: m / d; h d — the buried depth, unit: m; N— the empirical coefficient, 40 for clay, 30 for loam, and 20 for sandy loam. Specifically, according to the test results and time experience in various places, when the soil improvement filter material, buried conduit filter material and buried depth are in the range of 0.4-1.0 m, the approximate spacing of various different soil textures is: 8-14 m for clay, 14-20 m for loam, and 20-24 m for sand. More specifically, the above method is based on a large amount of test data and practical experience, and is obtained by induction analysis and generalization optimization, so as to obtain the relationship between the filter channel spacing and some indexes or other simplified indexes which have a decisive influence on the main influencing factors such as saline-alkali soil quality, for selection in design. Preferably, the formula method and field test method can be combined when determining the buried conduit spacing, and after theoretical formula calculation, field test is performed for corresponding adjustment: at the same time, the influence of local specific crop growth requirements on the filter channel spacing should be considered; the field test method is to select a representative site in terms of saline-alkali genesis, soil and hydrogeological conditions, crop types and agricultural technology in the saline-alkali treatment area, and through on-site observation of the improvement effect under various depth and spacing combinations, to select the ideal combination of spacing and buried depth.

[0041] The vertical shaft salt control and alkali discharge channel 3 penetrates the water-permeable alkali discharge channel from the topsoil layer 8, the subsoil layer 6 to the bottom soil layer 7 by filling the vertical shaft filter in the vertical shaft, and the depth of the vertical shaft is 60-100 cm. The vertical shaft salt control and alkali discharge channel 3 is positioned according to the position and area S of the micro-domain alkali spot area 9, and the number n of vertical shafts is set, and the single-well radiation area is 10 m2, and the following relationship is satisfied: n=S / 10.

[0042] In the moderate saline-alkali soil area, the depth of the vertical shaft is preferably 60 cm and is connected to the underground passage salt control and alkali discharge channel 2; in the heavy saline-alkali soil area, the depth of the vertical shaft is preferably 80-100 cm and is connected to the underground passage salt control and alkali discharge channel 2; and the diameter of the vertical shaft is preferably 10 cm.

[0043] The present application can also cooperate with the original underground passage channel 4, and the original underground passage channel 4 is fused with each soil layer salt control and alkali discharge channel to form a three-dimensional network salt control and alkali discharge channel underground, so as to realize the drainage and salt control and alkali discharge of the whole soil layer of the saline-alkali soil, and can inhibit the return of saline-alkali water, so as to avoid the aggravation of the salinization of the saline-alkali soil caused by the accumulation and return of the saline-alkali water.

[0044] The three-dimensional network drainage and salt control and alkali discharge method of the present application comprises the following steps:

[0045] Step S100, laying the soil improvement salt control and alkali discharge channel 1 in the subsoil layer 6 of the saline-alkali soil to be improved, and the top of the soil improvement salt control and alkali discharge channel 1 extends into the topsoil layer 8, so as to discharge the saline-alkali water in the topsoil layer 8 and the subsoil layer 6 from the soil body through the drainage ditch 10 or the water collecting pipe;

[0046] Step S200, laying the underground passage salt control and alkali discharge channel 2 in the bottom soil layer 7 of the saline-alkali soil to be improved, so as to discharge the saline-alkali water below the subsoil layer 6 through the drainage ditch 10 or the water collecting pipe, and discharge the returned saline-alkali water below the bottom soil layer 7; and

[0047] Step S300, drilling the vertical shaft salt control and alkali discharge channel 3 in the micro-domain alkali spot area 9 of the saline-alkali soil to be improved, so as to penetrate the water-permeable alkali discharge channel from the topsoil layer 8, the subsoil layer 6 to the bottom soil layer 7.

[0048] A plurality of soil improvement salt control and alkali discharge channels 1 can be laid transversely and in parallel in the subsoil layer 6, and are connected to the drainage ditch 10 or the water collecting pipe; a plurality of underground passage salt control and alkali discharge channels 2 can be laid longitudinally and in parallel in the bottom soil layer 7, and are connected to the drainage ditch 10 or the water collecting pipe; and a plurality of vertical shaft salt control and alkali discharge channels 3 can be drilled vertically in the micro-domain alkali spot area 9 to form a three-dimensional network drainage and salt control and alkali discharge channel.

[0049] The soil improvement and salt control drainage channel 1 is located in the subsoil layer 6 at a depth of 20cm to 40cm. The channel width is preferably 10cm. It is filled with soil improvement filter material, which can be organic materials such as straw. The soil above ground in saline-alkali soil contains a clay layer, which has poor permeability and low leaching desalination efficiency. The soil above ground is deeply loosened and broken up to cut off the soil's upward capillary and reduce the upward evaporation of soil salt. During irrigation, the loosened soil will leach salt to below the root zone, achieving the purpose of desalination and salt control. The filter material is transported into the trench at the same time as the trench is opened, completing the laying of the soil improvement and salt control drainage channel 1. The permeability coefficient of the soil above ground with this channel is increased by 3-5 times, effectively draining the salt in the soil above ground to the bottom soil.

[0050] The underground salt-controlling and alkali-draining channel 2 is located in the subsoil layer 7 at a depth of 40cm to 60cm. The channel diameter is preferably 8cm, and it is filled with underground filter material. The accumulation of salt and alkali in the subsoil layer 7, which cannot be drained, will cause the salt and alkali to rise and exacerbate the salinity of the upper soil. An 8cm diameter underground channel is plowed out in the subsoil layer 7 and filled with underground filter material, thus completing the laying of the underground salt-controlling and alkali-draining channel 2. This channel can drain the brine from the upper soil. If the brine exceeds the drainage capacity of this channel, it can continue to infiltrate and be drained through underground pipes below the channel. The filter material is preferably graded sand filter material, with a gradation specification of 30% fine sand (particle size less than 0.25mm), 30% medium sand (particle size less than 0.5mm), 25% coarse sand (particle size less than 1mm), and 15% fine aggregate (particle size less than 5mm).

[0051] The preferred vertical well for controlling salt and alkali drainage is a 10cm diameter well with a depth of 1m, filled with filter media. Saline-alkali soil often has a compacted layer with poor permeability, resulting in severe water blockage. This is addressed by drilling to break up the compacted layer and filling the holes with filter media to construct the vertical well for controlling salt and alkali drainage, connecting the upper and lower layers of the compacted soil for drainage. The preferred filter media is graded sand, comprising 50% coarse sand (particle size less than 1mm) and 50% fine aggregate (particle size less than 5mm).

[0052] like Figure 3 As shown, in some embodiments, a soil improvement and salt control drainage channel 1 is provided between two adjacent longitudinal underground pipe channels 4, and two transverse underground salt control and alkali drainage channels 2 are provided. Specifically, the soil improvement filter material in the soil improvement and salt control drainage channels 1 and the underground filter material in the underground salt control and alkali drainage channels 2, which are arranged in a crisscross pattern in space, can more fully and comprehensively cover the entire saline-alkali land for salt control and alkali drainage. Preferably, the soil improvement and salt control drainage channels 1 are arranged in an equidistant array relative to the underground pipe channels 4, and the underground salt control and alkali drainage channels 2 are arranged perpendicular to the underground pipe channels 4. The vertical filter material is vertically arranged for severely saline-alkali soil and micro-alkaline patches 9, so as to ensure that the three-dimensional mesh drainage and salt control drainage channels spatially cover the entire saline-alkali land, achieving uniform and efficient drainage and salt control drainage.

[0053] In some embodiments, the depth of the salt accumulation layer of the subsoil layer 6 is obtained by soil profile sampling method, which is used to determine the depth of the improved soil filter. Specifically, the depth of the improved soil salt control and alkali discharge channel 1 is higher than that of the underground salt control and alkali discharge channel 2, and the depth of the underground salt control and alkali discharge channel 2 is higher than that of the underground channel 4, and the vertical shaft salt control and alkali discharge channel 3 vertically communicates with the topsoil layer 8, the subsoil layer 6 and the bottom soil layer 7 to ensure that the salt in the whole soil layer can be effectively discharged.

[0054] In some embodiments, the depth of the improved soil salt control and alkali discharge channel 1 is preferably 20-40 cm, and the depth of the underground salt control and alkali discharge channel 2 is preferably 40-60 cm. The depth of the vertical shaft salt control and alkali discharge channel 3 is preferably 1 m. Since the improved soil salt control and alkali discharge channel 1 is only used to discharge the saline-alkaline moisture of the topsoil layer 8 and the subsoil layer 6, and the underground salt control and alkali discharge channel 2 not only discharges the saline-alkaline moisture of the soil below the improved soil salt control and alkali discharge channel 1, but also discharges the saline-alkaline moisture returned from the bottom soil layer 7, therefore, the water flow in the second underground salt control and alkali discharge channel 2 is greater than that in the improved soil salt control and alkali discharge channel 1, and accordingly, the diameter of the underground filter 12 cm is greater than the diameter of the improved soil filter 10 cm and less than the diameter of the underground channel 16 cm, which can save resources and reduce costs, and meet the salt control and alkali discharge requirements of the embodiments.

[0055] Referring to Figure 1 and Figure 4 , Figure 4 is a plan view of an embodiment of the present application. In this embodiment, the method is implemented in a field of 8 mu (200m*200m), and the specific parameters are shown in the following table:

[0056]

[0057] The soil profile sampling method is used to obtain the data of the heart soil layer 6 and the bottom soil layer 7 and the existing buried depth of the pipe, so as to determine the buried depth of the improved soil and salt control and alkali discharge channel 1, the dark channel salt control and alkali discharge channel 2 and the vertical shaft salt control and alkali discharge channel 3. The improved soil and salt control and alkali discharge channel 1 is constructed by burying the improved soil filter in the heart soil layer 6, with a diameter of 10 cm and a buried depth of 20-40 cm. The dark channel salt control and alkali discharge channel 2 is constructed by burying the dark channel filter in the bottom soil layer 7, with a diameter of 12 cm and a buried depth of 40-60 cm. The vertical shaft salt control and alkali discharge channel 3 is constructed by filling the vertical shaft filter in the vertical shaft, with a diameter of 10 cm and a vertical shaft depth of 60-100 cm, so as to form a water-permeable alkali discharge channel from the surface soil layer 8, the heart soil layer 6 to the bottom soil layer 7. The improved soil and salt control and alkali discharge channel 1 includes a plurality of laterally parallel buried improved soil filters. The dark channel salt control and alkali discharge channel 2 includes a plurality of vertically parallel buried dark channel filters. For the micro-domain alkali spot area 9, one or more vertical shaft salt control and alkali discharge channels 3 are arranged, which include a plurality of vertically buried vertical shaft filters. The existing dark pipe channel 4 can also be combined. The un-discharged salt water in the bottom soil layer 7 will continue to flow downward and be discharged through the dark pipe. At the same time, the salt water that is not discharged through the dark pipe will be discharged through the dark channel salt control and alkali discharge channel 2.

[0058] The embodiment is aimed at the problem that the salt and alkali in the upper layer (the surface soil layer 8 and the heart soil layer 6) of the saline-alkali soil cannot be discharged due to poor permeability, and the upward return of the salt and alkali in the bottom layer aggravates the soil salinization. The soil permeability is enhanced, the soil capillary action is reduced, the full-soil-layer drainage and salt control and alkali discharge channel is constructed, and the salt content in the bottom soil is reduced. The salt in the upper layer (the surface soil layer 8 and the heart soil layer 6) of the soil is effectively discharged to the bottom soil by increasing the soil water permeability coefficient by 3-5 times through the improved soil and salt control and alkali discharge channel 1. The dark channel salt control and alkali discharge channel 2 in the bottom soil layer 7 discharges the salt water discharged from the upper layer of soil. If the salt water is too much to exceed the drainage capacity of the channel, it can continue to infiltrate and be discharged through the dark pipe under the dark channel. The vertical shaft salt control and alkali discharge channel 3 breaks the impermeable layer and connects the channels of the upper and lower soil layers. In the rainy season, the underground water level rises, the dark channel salt control and alkali discharge channel 2 is above the underground water level, the upward flowing underground water is discharged into the drainage ditch 10 or the water collector through the channel, and the flood control effect is achieved. In the spring thawing period, the filter channel has good permeability, improves the soil permeability, and effectively and quickly improves the ground temperature. The organic material (such as straw) in the improved soil and salt control and alkali discharge channel 1 plays the role of straw returning to the field, creates a good soil environment for the development and growth of crop roots, increases the soil organic matter content, improves the land productivity, and increases the solubility of anions and cations in the soil, so as to promote soil desalination.

[0059] The application forms a three-dimensional netted drainage salt control and alkali discharge channel by reasonable setting, increases the drainage channel, improves the drainage capacity, suppresses salt accumulation, and makes the saline-alkali soil layer above the groundwater level realize efficient and rapid salt control and discharge. In addition, the underground passage salt control and alkali discharge channel 2 can effectively prevent salt and alkali from returning in spring, prevent salt from being collected on the surface, quickly improve the ground temperature, and improve crop yield and land productivity; the underground passage salt control and alkali discharge channel 2 controls and discharges salt and alkali in the bottom soil layer 7 while receiving the moisture discharged by the un-reformed soil salt control and alkali discharge channel 1 in the heart soil layer 6; the vertical shaft salt control and alkali discharge channel 3 penetrates the topsoil layer 8, the heart soil layer 6 and the bottom soil layer 7 from top to bottom, breaks the impermeable layer, and effectively discharges the salt in the micro-domain alkali spot area 9 through the vertical shaft filter material; the three-dimensional netted drainage salt control and alkali discharge channel achieves the purpose of controlling and washing salt in the whole soil layer. At the same time, the groundwater level is controlled below the critical depth, and the soil salt return and secondary salinization are prevented.

[0060] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application. However, these corresponding changes and modifications should all belong to the protection scope of the claims attached to the present application.

Claims

1. A method for controlling salt and alkali discharge in a three-dimensional mesh drainage system, characterized by, By setting the three-dimensional network drainage salt control and alkali discharge channel, the whole soil layer salt control and washing salt is realized, and the groundwater level is controlled below the critical depth, preventing soil salt return and secondary salinization, including the following steps: S100, laying the soil improvement salt control and alkali discharge channel in the heart soil layer of the salt-alkali soil to be improved, the top of the soil improvement salt control and alkali discharge channel extending into the surface soil layer for discharging the salt-alkali water in the surface soil layer and the heart soil layer out of the soil body; S200, laying the tunnel salt control and alkali discharge channel in the bottom soil layer of the salt-alkali soil to be improved for discharging the salt-alkali water below the heart soil layer and the salt-alkali water returned above the bottom soil layer; and S300, drilling the vertical shaft salt control and alkali discharge channel in the micro-domain alkali spot area of the salt-alkali soil to be improved for opening the water-permeable alkali discharge channel from the surface soil layer, the heart soil layer to the bottom soil layer, breaking the impermeable layer and effectively discharging the salt in the micro-domain alkali spot area through the vertical shaft filter material; The vertical shaft salt control and alkali discharge channel opens the water-permeable alkali discharge channel from the surface soil layer, the heart soil layer to the bottom soil layer through the vertical shaft filter material filled in the vertical shaft, the depth of the vertical shaft being 60-100 cm; the vertical shaft salt control and alkali discharge channel is positioned and the number of vertical shafts n is set according to the position and area S of the micro-domain alkali spot area, the single-well radiation area being 10 m2 and satisfying the following relationship: n=S / 10; In the moderate salt-alkali soil area, the depth of the vertical shaft is 60 cm and is connected with the tunnel salt control and alkali discharge channel; in the severe salt-alkali soil area, the depth of the vertical shaft is 80-100 cm and is connected with the tunnel salt control and alkali discharge channel; The plurality of soil improvement salt control and alkali discharge channels are laid transversely and in parallel in the heart soil layer; the plurality of tunnel salt control and alkali discharge channels are laid longitudinally and in parallel in the bottom soil layer; and the plurality of vertical shaft salt control and alkali discharge channels are drilled vertically in the micro-domain alkali spot area, forming the three-dimensional network drainage salt control and alkali discharge channel; The tunnel salt control and alkali discharge channel can effectively prevent salt-alkali return in spring, prevent salt deposition on the surface, rapidly increase the ground temperature, and improve the crop yield and the land productivity; and the tunnel salt control and alkali discharge channel controls the salt and discharges the alkali in the bottom soil layer while receiving the water not discharged by the soil improvement salt control and alkali discharge channel in the heart soil layer.

2. The three-dimensional reticulated drainage and salinity control and alkaline discharge method according to claim 1, characterized in that, The soil improvement salt control and alkali discharge channel constructs the water-permeable alkali discharge channel of the heart soil layer through the soil improvement filter material buried in the heart soil layer, the laying depth of the soil improvement filter material being not less than the depth of the heart soil layer.

3. The three-dimensional reticulated drainage and salinity control and alkaline discharge method according to claim 1, characterized in that, The tunnel salt control and alkali discharge channel constructs the water-permeable alkali discharge channel of the bottom soil layer through the soil improvement filter material buried in the bottom soil layer, the burying depth of the tunnel salt control and alkali discharge channel being 40-60 cm.

4. The three-dimensional reticulated drainage and salinity control and alkaline discharge method according to claim 3, characterized in that, The adjacent dark channel distance of the salt control alkali channel is L, the soil permeability coefficient is K, and the dark channel burial depth is h d , the soil empirical coefficient is N, and the adjacent dark channel distance L satisfies the following relationship: L=NKh d .

5. The three-dimensional reticulated drainage and salinity control and alkaline discharge method according to claim 1, wherein, The diameter of the vertical shaft is 10 cm.

6. A three-dimensional network drainage salt control and alkali discharge system constructed by the three-dimensional network drainage salt control and alkali discharge method according to any one of claims 1-5.

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