Methods for treating saline soil foundations, structural and road construction methods

Abstract

This invention provides a method for treating saline-alkali soil foundations, comprising: Step 11, selecting a treatment area, constructing an over-excavated soil layer in the treatment area, and setting up a drainage ditch outside the edge of the treatment area; Step 12, compacting the over-excavated surface of the treatment area, laying a one-way permeable layer, wherein the water inlet surface of the one-way permeable layer faces the surface of the treatment area, and the surface of the one-way permeable layer has a preset slope; Step 13, laying a crystalline layer on the one-way permeable layer, wherein the crystalline layer is filled with a porous medium, and the crystalline layer is connected to the drainage ditch; Step 14, allowing surface water to enter the crystalline layer, and the surface water flows along the preset slope of the one-way permeable layer into the drainage ditch for discharge. This invention also provides a structure for treating saline-alkali soil foundations and a road construction method. The saline-alkali soil foundation treatment method, structure, and road construction method of this invention can solve the technical problems of easy corrosion and failure of the partition layer and the inability to eliminate salt swelling in the prior art.

Description

Technical Field

[0001] This invention relates to the field of foundation soil treatment technology, specifically to a method, structure, and road construction method for treating saline soil foundations. Background Technology

[0002] Airport flight zones and similar structures have high requirements for pavement smoothness, slope, and elevation, necessitating strict control over pavement and subgrade settlement, uplift, and uneven settlement and uplift. In saline soil areas, the subsurface of pavements and airport pavements frequently suffers from salt swelling under dry conditions and dissolution and corrosion under wet or rainy conditions. This leads to uneven uplift, subsidence, twisting, cracking, and deformation of the pavement, affecting vehicle and aircraft takeoffs, landings, taxiing, and safety.

[0003] Numerous experimental studies and construction projects have been conducted both domestically and internationally to address the problems of salt swelling and dissolution in saline soils, achieving some success. The traditional method involves treating roadbed saline soil foundations by installing a barrier layer. Typically, a layer of crushed stone or gravel is placed beneath the road surface or pavement, and sometimes geomembranes or fabrics are used to wrap it, preventing capillary water rise and surface water infiltration. Installing a barrier layer of a certain thickness effectively blocks the rise of capillary water and salt, avoiding damage to the road surface, pavement, and foundation.

[0004] However, existing processing methods generally have the following problems:

[0005] Vertically, although geomembranes can prevent groundwater from rising to the road surface and pavement structure, saline groundwater in saline foundations is prone to crystallization under low temperatures and drought, leading to salt swelling. In other words, the salt swelling problem is transferred beneath the geomembrane and is not eliminated. Over time, the top surface of the foundation continues to rise, causing uneven uplift, twisting, and deformation of the road surface and pavement. If surface water enters from the road surface or seeps into the top of the foundation from the edges, the foundation is prone to dissolution. Furthermore, the saline water cannot be drained, leading to geomembrane corrosion and loss of its insulating properties. Summary of the Invention

[0006] The purpose of this invention is to provide a method, structure, and road construction method for treating saline soil foundations, solving the technical problems of easy corrosion and failure of the partition layer and the inability to eliminate salt swelling in the prior art.

[0007] To achieve the above objectives, the present invention provides a method for treating saline soil foundations, comprising: Step 11, selecting a treatment area, constructing an over-excavated soil layer in the treatment area, and setting up a drainage ditch outside the edge of the treatment area; Step 12, compacting the over-excavated treatment area surface, laying a one-way permeable layer on the compacted treatment area surface, wherein the water inlet surface of the one-way permeable layer faces the treatment area surface, and the surface of the one-way permeable layer has a preset slope; Step 13, laying a crystalline layer on the one-way permeable layer, wherein the crystalline layer is filled with a porous medium, and the crystalline layer is connected to the drainage ditch; Step 14, allowing surface water to enter the crystalline layer, and the surface water enters the drainage ditch along the preset slope of the one-way permeable layer and is discharged.

[0008] The present invention also provides a saline soil foundation treatment structure based on the saline soil foundation treatment method, comprising: a one-way permeable layer having an inlet surface and an outlet surface, the inlet surface facing the ground of the treatment area, and the surface of the one-way permeable layer having a preset slope; a crystalline layer filled with a porous medium, the outlet surface facing the crystalline layer; and a drainage ditch connected to the crystalline layer.

[0009] This invention also provides a road construction method, comprising: step 101, constructing an over-excavated soil layer for the road foundation, and setting drainage ditches outside the edge of the road foundation; step 102, compacting the surface of the over-excavated road foundation, and laying a one-way permeable layer on the compacted road foundation surface, wherein the water inlet surface of the one-way permeable layer faces the road foundation surface, and the surface of the one-way permeable layer has a preset slope; step 103, laying a crystalline layer on the one-way permeable layer, wherein the crystalline layer is filled with a porous medium, and the crystalline layer is connected to the drainage ditches; step 104, laying a filter layer on the crystalline layer, and covering at least a portion of the filter layer with the outer edge of the one-way permeable layer; step 105, laying the road surface on the filter layer.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0011] The present invention relates to a method, structure, and road construction method for treating saline soil foundations. By laying a one-way permeable layer and a crystallization layer, saline groundwater (capillary water) migrates upward within the saline soil foundation, passing through the one-way permeable layer and entering the crystallization layer. Utilizing the principle that saline groundwater cannot migrate upward within porous media, this method hinders the upward migration of saline capillary water, accommodates saline capillary water and salt crystals, and prevents long-term accumulation of saline groundwater under the one-way permeable layer, thus avoiding corrosion and salt swelling. Furthermore, while preventing surface water infiltration into the foundation and thus preventing subsidence, it also allows saline groundwater to drain smoothly, rather than merely isolating it from the upper structural layer. Therefore, it effectively eliminates salt swelling, prevents settlement and heaving of the pavement and roadbed, and allows non-salt-containing surface water to enter and dissolve crystalline salts, preventing long-term accumulation of salt crystals on the one-way permeable layer.

[0012] Preferably, step 12 further includes: laying a protective layer on the unidirectional permeable layer. The protective layer can protect the unidirectional permeable layer from damage and prevent the slippage of the overlying crystalline layer; the protective layer also has a heat insulation function, which can prevent the unidirectional permeable layer from being damaged by soil frost heave; the permeability of the protective layer can play a role in drainage.

[0013] Preferably, the one-way permeable layer is laid on the bottom and sidewalls of the drainage ditch, with the water inlet surface of the one-way permeable layer facing the bottom and sidewalls of the drainage ditch to avoid disturbance from surface water outside the treatment area.

[0014] Preferably, a filter layer is laid on the crystallized layer to prevent the upper mud and sand from leaking into the crystallized layer and to ensure the stability of the upper pavement and other structural layers.

[0015] Preferably, the outer edge of the one-way permeable layer is flipped over to cover at least a portion of the reverse filter layer to prevent saline water in the crystallization layer from seeping out from the side of the crystallization layer.

[0016] Preferably, the saline soil foundation treatment structure further includes a protective layer, which is laid on the one-way permeable layer.

[0017] Preferably, the bottom and sidewalls of the drainage ditch are covered with a one-way permeable layer, and the water inlet surface faces the bottom and sidewalls of the drainage ditch.

[0018] Preferably, the saline soil foundation treatment structure further includes a filter layer, which is laid on the crystallization layer, and the outer edge of the one-way permeable layer covers at least a portion of the filter layer. Attached Figure Description

[0019] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of the saline soil foundation treatment method in an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the saline soil foundation treatment structure in an embodiment of the present invention.

[0022] The structure includes a one-way permeable layer 1, a crystallization layer 2, a drainage ditch 3, a protective layer 4, and a filter layer 5. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0025] Figure 1 This is a schematic flowchart of a method for treating saline soil foundations provided in an embodiment of the present invention. Figure 1 As shown, an embodiment of the present invention provides a method for treating saline soil foundations, comprising:

[0026] Step 11: Select the treatment area, carry out over-excavation of the soil layer in the treatment area, and set up drainage ditches outside the edge of the treatment area.

[0027] The treatment area is selected as the pre-defined range extending beyond the airport flight area and its road surface and shoulder edges. For example, for areas with saline soil covering the entire area, the treatment area is defined as extending 3 meters beyond the road surface and shoulder edges; for areas with saline soil covering only a portion of the area, the treatment area for non-saline soil areas with a width of 2 meters or more beyond the road surface and shoulder edges is defined as extending 2 meters beyond the road surface and shoulder edges, and for areas within 2 meters, it is defined as extending 3 meters beyond the road surface and shoulder edges.

[0028] The over-excavation thickness of the over-excavated soil layer in the treatment area is determined based on the original ground elevation, the design elevation of the terrain, the thickness of the road surface, the pavement, the shoulder, and the crystalline layer.

[0029] Step 12: Compact the ground of the over-excavated treatment area, and lay a one-way permeable layer on the compacted treatment area ground. The water inlet surface of the one-way permeable layer faces the treatment area ground, and the surface of the one-way permeable layer has a preset slope.

[0030] Specialized geomembranes or other materials with unidirectional permeability can be selected from existing technologies as the unidirectional permeable layer. The unidirectional permeable layer has an inlet surface and an outlet surface, allowing liquid to pass through only from the inlet surface to the outlet surface. The inlet surface faces the ground surface of the treatment area, allowing saline capillary water and groundwater to pass upwards through the unidirectional permeable layer, while water above the unidirectional permeable layer cannot pass downwards. The surface slope of the unidirectional permeable layer is preferably not less than 2%, and the bonding width between adjacent unidirectional permeable layers is preferably not less than 30 cm to ensure stable and firm bonding.

[0031] Step 13: Lay a crystalline layer on the unidirectional permeable layer. The crystalline layer is filled with a porous medium and is connected to the drainage ditch.

[0032] Various materials available in the prior art can be selected as porous media, such as gravel, sandstone, or accumulations of artificial granular materials. A porous media with relatively uniform particle size is preferred, ideally 5–10 cm. The thickness of the crystalline layer is determined based on the degree of development of the saline soil in the treatment area, and is preferably 50–80 cm.

[0033] Drainage ditches are set up outside the treatment area to remove surface water entering the treatment area, as well as capillary water and its salts rising into the crystal layer, and to prevent surface water from outside the treatment area from disturbing it.

[0034] In some preferred embodiments, after excavating the drainage ditch, the bottom surface of the drainage ditch is compacted, and the one-way permeable layer is laid on the bottom surface and sidewalls of the drainage ditch, with the water inlet surface of the one-way permeable layer facing the bottom surface and sidewalls of the drainage ditch. In some more preferred embodiments, the protective layer is laid inside the one-way permeable layer in the drainage ditch, and a crystalline layer is laid on the protective layer.

[0035] In some preferred embodiments, step 12 further includes laying a protective layer on the unidirectional permeable layer.

[0036] Materials such as geotextiles with bidirectional permeability can be selected as the protective layer. The crystalline layer is laid on top of the protective layer. The protective layer can protect the unidirectional permeable layer from damage and prevent the crystalline layer above from slipping. The protective layer also has a heat insulation function, which can prevent the unidirectional permeable layer from being damaged by soil frost heave. The permeability of the protective layer can also play a role in drainage.

[0037] In some preferred embodiments, a filter layer is laid on the crystalline layer, and the upper pavement and other structural layers are laid on top of the filter layer to prevent the upper mud and sand from leaking into the crystalline layer and to ensure the stability of the upper pavement and other structural layers. The filter layer can be a geosynthetic material such as geotextile with bidirectional permeability. The area of ​​the filter layer is not less than the surface of the crystalline layer, and preferably extends 1m beyond the edge of the crystalline layer.

[0038] In some preferred embodiments, the outer edge of the one-way permeable layer is flipped over at least a portion of the reverse filter layer to prevent saline water from seeping out from the side of the crystallization layer.

[0039] Step 14: Allow surface water to enter the crystallization layer, and allow the surface water to flow along the preset slope of the one-way permeable layer into the drainage ditch for discharge.

[0040] The treatment process of this invention for saline soil foundations involves laying a one-way permeable layer and a crystallization layer. This allows saline groundwater (capillary water) to migrate upwards within the saline soil foundation, passing through the one-way permeable layer and entering the crystallization layer. Utilizing the principle that saline groundwater cannot migrate upwards in porous media, the crystallization layer hinders the further upward movement and penetration of the saline capillary water. This causes the salts in the saline groundwater to crystallize and accumulate in the voids at the bottom of the crystallization layer and on the one-way permeable layer. The crystallization layer has a certain thickness, with numerous pores sufficient to accommodate salt crystallization, thus preventing salt swelling. Surface water generated by natural rainfall or periodic artificial watering can enter the crystallization layer through gaps in the pavement. This surface water dissolves the crystallized salts in the crystallization layer and then flows along the slope of the one-way permeable layer into the drainage ditch, unable to penetrate the one-way permeable layer into the soil outside the treatment area, such as the saline soil foundation. When surface water flows into the drainage ditch, it carries the dissolved salts out of the crystal layer, eliminating the possibility of salt accumulation, gradually filling the voids in the crystal layer, and corroding the one-way permeable layer, thus maintaining the long-term effectiveness of the geomembrane.

[0041] Compared with the prior art, the saline soil foundation treatment method of the present invention can, on the one hand, prevent the upward migration of saline capillary water, accommodate saline capillary water and salt crystals, and avoid the long-term accumulation of saline groundwater under the one-way permeable layer, which would cause corrosion and salt swelling; on the other hand, while preventing surface water from seeping into the foundation to prevent subsidence, it can also allow saline groundwater to drain smoothly, rather than just being isolated from the upper structural layer. Therefore, it can truly eliminate salt swelling and prevent the pavement and foundation from settling and heaving. At the same time, it allows non-salt-free surface water to enter and dissolve crystalline salts, preventing salt crystals from accumulating on the one-way permeable layer for a long time.

[0042] Accordingly, such as Figure 2 As shown, this embodiment of the invention also provides a saline soil foundation treatment structure based on the saline soil foundation treatment method, comprising: a unidirectional permeable layer 1, the unidirectional permeable layer 1 having an inlet surface and an outlet surface, the inlet surface facing the ground of the treatment area, and the surface of the unidirectional permeable layer 1 having a preset slope; a crystallization layer 2, the crystallization layer 2 being filled with a porous medium, the outlet surface facing the crystallization layer 2; and a drainage ditch 3, the drainage ditch 3 being connected to the crystallization layer 2.

[0043] Specifically, the saline soil foundation treatment structure also includes a protective layer 4, which is laid on a one-way permeable layer 1.

[0044] Specifically, the bottom and sidewalls of the drainage ditch 3 are covered with a one-way permeable layer 1, with the water inlet facing the bottom and sidewalls of the drainage ditch 3.

[0045] Specifically, the saline soil foundation treatment structure also includes a filter layer 5, which is laid on the crystallization layer 2, and the outer edge of the one-way permeable layer 1 covers at least a portion of the filter layer 5.

[0046] This invention also provides a road construction method, comprising: step 101, over-excavating the road foundation and setting up drainage ditches outside the edge of the road foundation; step 102, compacting the surface of the over-excavated road foundation and laying a one-way permeable layer on the compacted road foundation surface, wherein the water inlet surface of the one-way permeable layer faces the road foundation surface and the surface of the one-way permeable layer has a preset slope; step 103, laying a crystalline layer on the one-way permeable layer, wherein the crystalline layer is filled with a porous medium and the crystalline layer is connected to the drainage ditches; step 104, laying a filter layer on the crystalline layer and covering at least a portion of the filter layer with the outer edge of the one-way permeable layer; and step 105, laying the road surface on the filter layer.

[0047] For a detailed description of the relevant parts of the saline soil foundation treatment structure and road construction method disclosed in this embodiment of the invention, please refer to the detailed description of the corresponding parts of the saline soil foundation treatment method provided in this embodiment of the invention, which will not be repeated here. Furthermore, the parts of the technical solutions provided in this embodiment of the invention that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0048] The above description of various embodiments of the present invention is provided to those skilled in the art only to illustrate the technical solutions of the present invention. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, various alternatives and variations of the present invention will be apparent to those skilled in the art. Therefore, although some alternative embodiments have been specifically discussed, other embodiments will be obvious or readily apparent to those skilled in the art. The present invention is intended to include all alternatives, modifications, and variations of the invention already discussed herein, as well as other embodiments falling within the spirit and scope of the foregoing claims.

[0049] Although the invention has been described by way of embodiments, those skilled in the art will recognize that the invention has many variations and modifications without departing from its spirit, and it is intended that the appended claims cover such variations and modifications without departing from the spirit of the invention.

Claims

1. A method for treating a saline soil foundation, comprising: Step 11, selecting a treatment area, performing over-excavation of soil layers in the treatment area, and setting a drainage ditch outside the edge of the treatment area; Step 12, rolling the ground surface of the treatment area after over-excavation, laying a unidirectional water permeable layer on the ground surface of the treatment area after rolling, the water inlet surface of the unidirectional water permeable layer facing the ground surface of the treatment area, and the surface of the unidirectional water permeable layer having a preset slope; Step 13, laying a crystalline layer on the unidirectional water permeable layer, the crystalline layer being filled with a porous medium with porosity, and the crystalline layer being connected to the drainage ditch; Step 14, allowing surface water to enter the crystalline layer, and the surface water entering the drainage ditch along the preset slope of the unidirectional water permeable layer.

2. The method for treating a saline soil foundation according to claim 1, characterized by, The step 12 further comprises: laying a protective layer on the unidirectional water permeable layer.

3. The method for treating a saline soil foundation according to claim 1, characterized by, The unidirectional water permeable layer is laid on the bottom surface and side wall of the drainage ditch, and the water inlet surface faces the bottom surface and side wall of the drainage ditch.

4. The method of claim 1, wherein A filter layer is laid on the crystalline layer.

5. The method of claim 4, wherein The outer edge of the unidirectional water permeable layer is folded on at least part of the filter layer.

6. A salinity ground treatment structure based on the salinity ground treatment method according to claim 1, characterized by, Comprising: a unidirectional water permeable layer having a water inlet surface and a water outlet surface, the water inlet surface facing the ground surface of the treatment area, and the surface of the unidirectional water permeable layer having a preset slope; a crystalline layer filled with a porous medium with porosity, the water outlet surface facing the crystalline layer; a drainage ditch connected to the crystalline layer.

7. The salinated soil foundation treatment structure according to claim 6, wherein The saline soil foundation treatment structure further comprises a protective layer laid on the unidirectional water permeable layer.

8. The salinated soil foundation treatment structure according to claim 6, wherein The unidirectional water permeable layer is laid on the bottom surface and side wall of the drainage ditch, and the water inlet surface faces the bottom surface and side wall of the drainage ditch.

9. The salinated soil foundation treatment structure according to claim 6, wherein Further comprising a filter layer laid on the crystalline layer, and the outer edge of the unidirectional water permeable layer is folded on at least part of the filter layer.

10. A method for road construction, comprising: Step 101, performing over-excavation of soil layers in a road foundation, and setting a drainage ditch outside the edge of the road foundation; Step 102, rolling the surface of the road foundation after over-excavation, laying a unidirectional water permeable layer on the surface of the road foundation after rolling, the water inlet surface of the unidirectional water permeable layer facing the surface of the road foundation, and the surface of the unidirectional water permeable layer having a preset slope; Step 103, laying a crystalline layer on the unidirectional water permeable layer, the crystalline layer being filled with a porous medium with porosity, and the crystalline layer being connected to the drainage ditch; Step 104, laying a filter layer on the crystalline layer, and folding the outer edge of the unidirectional water permeable layer on at least part of the filter layer; Step 105, laying a road surface on the filter layer.

Images