Drainage and blockage combined novel composite liner separation layer for salinized soil roadbed and roadbed structure

Abstract

The invention provides a dredging and blocking combined salinized soil roadbed novel composite liner separation layer and a roadbed structure. The composite liner separation layer comprises a first layer of non-woven geotextile, an upper layer of three-dimensional geotextile drainage network, a second layer of non-woven geotextile, a polymer modified bentonite particle layer, a third layer of non-woven geotextile, a lower layer of three-dimensional geotextile drainage network and a fourth layer of non-woven geotextile which are sequentially arranged from top to bottom; the roadbed structure comprises a pavement structure layer, a roadbed, a composite liner partition layer and an embankment which are sequentially laid from top to bottom, and slope protection ways and drainage ditches are arranged on the two sides of the roadbed structure. Through the bentonite particle impermeable layer in the composite liner separation layer, infiltration of surface water can be prevented, and rising of capillary water and migration of water and salt under the action of temperature gradient can also be blocked; slope protection and drainage ditches are designed on the two sides of the roadbed, smooth salt and water drainage of the roadbed is guaranteed, and the risk of roadbed settlement caused by migration and uneven distribution of water and salt in the salinized soil roadbed is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed engineering, and in particular to a novel composite liner isolation layer and roadbed structure for a saline soil roadbed combining dredging and blocking. Background Art

[0002] With the continuous development, the demand for highway and railway construction is increasing. Many highway and railway routes pass through saline soil areas. A series of roadbed diseases such as salt expansion, frost expansion, and dissolution caused by the temperature difference inside the saline soil roadbed and the migration of water and salt need to be solved urgently.

[0003] The existing Chinese patent with publication number CN219490561U discloses a roadbed structure in high-latitude island frozen soil areas, wherein the structure includes a foundation pit, a base thermal insulation layer, a base waterproof layer, a base bed anti-freezing and heaving layer and a sealing layer. The base thermal insulation layer is laid at the bottom of the foundation pit, and the bottom of the base thermal insulation layer is in contact with the frozen soil layer; the base waterproof layer is laid above the base thermal insulation layer, and the bottom of the base waterproof layer is in contact with the top of the base thermal insulation layer, and both sides of the base waterproof layer are in contact with the frozen soil layer; the base bed anti-freezing and heaving layer is laid above the base waterproof layer, and the bottom of the base bed anti-freezing and heaving layer is in contact with the top of the base waterproof layer; the sealing layer is laid above the base bed anti-freezing and heaving layer, and the bottom of the sealing layer is in contact with the top of the base bed anti-freezing and heaving layer.

[0004] However, the composite geomembrane barrier layer technology ("two cloths and one membrane") currently used to treat saline soil roadbed diseases has an obvious "pot lid effect", that is, the moisture content of the shallow soil increases due to the closed overlying structure in the unsaturated soil, which prevents the water from being discharged.

[0005] Therefore, as the capillary water rises, a water-rich area will appear in the vicinity of the composite geomembrane barrier layer. The dissolution of soil salt in the water-rich area not only causes foundation subsidence and uneven settlement, but also significantly accelerates the destruction of the geomembrane under traffic loads, leading to major engineering diseases such as long cracks and significant rutting on the road surface. Therefore, it is necessary to design a new barrier layer technology that can combine dredging and blocking to effectively inhibit the migration of water and salt inside the roadbed. Summary of the invention

[0006] In view of the defects in the prior art, the purpose of the present invention is to provide a novel composite liner barrier layer and roadbed structure for saline soil roadbed that combines dredging and blocking.

[0007] According to the present invention, a new type of composite liner barrier layer for saline soil roadbed combining dredging and blocking is provided, the composite liner barrier layer includes, arranged in sequence from top to bottom: a first layer of non-woven geotextile, an upper three-dimensional geotextile drainage net, a second layer of non-woven geotextile, a polymer-modified bentonite granular layer, a third layer of non-woven geotextile, a lower three-dimensional geotextile drainage net and a fourth layer of non-woven geotextile, the polymer-modified bentonite granular layer is fastened between the second layer of non-woven geotextile and the third layer of non-woven geotextile by needle-punched fibers arranged at intervals.

[0008] Preferably, the composite liner insulation layer is arranged to be inclined downward from the center to both sides, with a slope of 2%.

[0009] Preferably, the non-woven geotextile of the composite liner insulation layer is made of polypropylene fiber, with a unit area mass of ≥200g / m 2 The unit area mass of the polymer modified bentonite particle layer is ≥4500g / m 2 The unit area mass of the composite liner insulation layer is ≥5000g / m 2 The three-dimensional geotextile drainage net of the composite liner isolation layer is made of polyethylene with a tensile strength of ≥36.5kN / m.

[0010] Preferably, the tensile strength of the composite liner barrier layer is ≥1000N / 10cm, the peel strength is ≥60N / 10cm, and the CBR bursting strength is ≥2.5kN.

[0011] Preferably, a plurality of the needle-punched fibers are vertically spaced inside the polymer-modified bentonite granular layer, and the polymer-modified bentonite granular layer is fixed between the second layer of non-woven geotextile and the third layer of non-woven geotextile by needle-punching.

[0012] Preferably, the upper three-dimensional geotextile drainage net is fixed between the first layer of non-woven geotextile and the second layer of non-woven geotextile by using a thermal bonding process.

[0013] Preferably, the lower three-dimensional geotextile drainage net is fixed between the third layer of non-woven geotextile and the fourth layer of non-woven geotextile by using a thermal bonding process.

[0014] A roadbed structure provided by the present invention adopts the above-mentioned novel composite liner barrier layer of saline soil roadbed combining dredging and blocking, and includes: a pavement structure layer, a roadbed, the composite liner barrier layer and an embankment laid in sequence from top to bottom, with slope protection roads and drainage ditches arranged on both sides.

[0015] Preferably, the slope protection road is symmetrically arranged on both sides of the composite liner isolation layer and the embankment, the width of the slope protection road is 3m, the slope protection road completely covers the composite liner isolation layer, and the composite liner isolation layer has no exposed surface.

[0016] Preferably, the drainage ditch is symmetrically arranged on both sides of the slope protection road with a slope of 1:1, and the distance between the drainage ditch and the slope protection road is 2m.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention can not only prevent the infiltration of surface water, but also block the rise of capillary water and the migration of water and salt under the action of temperature gradient through the bentonite particle anti-seepage layer in the composite liner barrier layer; by bonding a three-dimensional geotextile drainage net on the upper layer of the polymer modified bentonite liner layer, the excess water infiltrating from the upper part of the roadbed can be removed in time, thereby improving the ability to cope with extreme climates such as heavy rains; the three-dimensional geotextile drainage net on the lower layer can block the rise of capillary water and discharge the water accumulation in the lower part of the barrier layer caused by the "pot cover effect"; by designing slope protection and drainage ditches on both sides of the roadbed, it is ensured that the roadbed can drain salt and water smoothly during long-term operation, thereby reducing the risk of roadbed settlement caused by water and salt migration and uneven distribution in the saline soil roadbed.

[0019] 2. The present invention arranges four layers of geotextiles in the composite liner partition layer to separate the upper three-dimensional geotextile drainage net, modified bentonite particles, and the lower three-dimensional geotextile drainage net, respectively, thereby filtering water and isolating salt, preventing coarse particles from entering the three-dimensional geotextile drainage net to block the drainage channel, filtering the salt-containing brine in the saline soil to reduce the salt content in the water absorbed by the bentonite during hydration, and ensuring the stability of the anti-seepage performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0021] Figure 1 This is a cross-sectional view of the composite liner insulation layer mainly embodied in the present invention;

[0022] Figure 2 It is a cross-sectional view mainly showing the roadbed structure of the present invention.

[0023] As shown in the figure:

[0024] First layer of non-woven geotextile 1 needle-punched fiber 8

[0025] Upper three-dimensional geodrainage net 2 Pavement structure layer 9

[0026] The second layer of non-woven geotextile 3 roadbed 10

[0027] Polymer modified bentonite granular layer 4 Composite liner insulation layer 11

[0028] The third layer of non-woven geotextile 5 embankment 12

[0029] Lower three-dimensional geodrainage net 6 Slope protection 13

[0030] The fourth layer of non-woven geotextile 7 drainage ditch 14 DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0032] Example 1

[0033] like Figure 1 As shown, a new type of composite liner barrier layer for saline soil roadbed that combines dredging and blocking according to the present invention includes a composite liner barrier layer 11, which is arranged in sequence from top to bottom: a first layer of non-woven geotextile 1, an upper three-dimensional geotextile drainage net 2, a second layer of non-woven geotextile 3, a polymer-modified bentonite granular layer 4, a third layer of non-woven geotextile 5, a lower three-dimensional geotextile drainage net 6 and a fourth layer of non-woven geotextile 7. The polymer-modified bentonite granular layer 4 is fastened between the second layer of non-woven geotextile 3 and the third layer of non-woven geotextile 5 by needle-punched fibers 8 arranged at intervals.

[0034] The composite liner insulation layer 11 is arranged to be inclined downward from the center to both sides, with a slope of 2%.

[0035] The non-woven geotextile of the composite liner insulation layer 11 is made of polypropylene fiber, with a unit area mass of ≥ 200g / m 2 , the unit area mass of the polymer modified bentonite granular layer 4 is ≥4500g / m 2 The unit area mass of the composite liner insulation layer 11 is ≥5000g / m 2 The three-dimensional geodrainage net of the composite liner barrier layer 11 is made of high-density polyethylene with a tensile strength of ≥36.5kN / m. The tensile strength of the composite liner barrier layer 11 is ≥1000N / 10cm, the peel strength is ≥60N / 10cm, and the CBR bursting strength is ≥2.5kN. For high-cold frozen areas, if necessary, the permeability coefficient can be tested after 100 freeze-thaw cycles, which should be ≤5.0×10-8cm / s.

[0036] A plurality of rows of needle-punched fibers 8 are vertically spaced inside the polymer-modified bentonite granular layer 4 , and the polymer-modified bentonite granular layer 4 is fixed between the second layer of non-woven geotextile 3 and the third layer of non-woven geotextile 5 by needle-punching.

[0037] The upper three-dimensional geotextile drainage net 2 is fixed between the first layer of non-woven geotextile 1 and the second layer of non-woven geotextile 3 by using a thermal bonding process.

[0038] The lower three-dimensional geotextile drainage net 6 is fixed between the third layer of non-woven geotextile 5 and the fourth layer of non-woven geotextile 7 by using a thermal bonding process.

[0039] The composite liner barrier layer 11 of the present application plays a role of combining drainage and blocking in saline soil roadbed. The polymer-modified bentonite can play a good anti-seepage effect in saline soil roadbed with high salt concentration and high erosion. It can not only prevent the infiltration of surface water, but also block the rise of capillary water and the migration of water and salt under the action of temperature gradient.

[0040] In addition, compared with the traditional composite geomembrane barrier layer technology, the modified bentonite particles in the new composite liner need to absorb a large amount of water during the hydration process, which prevents the accumulation of condensed water under the liner caused by the "pot lid effect". The upper three-dimensional geotextile drainage net 2 in the new composite liner can discharge the excess water that the polymer modified bentonite hydration process fails to absorb in time from the roadbed. The lower three-dimensional geotextile drainage net 6 can prevent the capillary water from rising, and discharge the water vapor in the lower roadbed that evaporates upward and condenses and accumulates below the barrier layer. At the same time, the upper and lower drainage nets protect the polymer modified bentonite liner layer in the middle, preventing the coarse particle filler of the roadbed from puncturing the liner. The "blocking" of the bentonite layer and the "draining" of the drainage net layer enable the new composite liner of the present application to play a "draining and blocking combination" role in the saline soil roadbed, thereby effectively suppressing a series of saline soil roadbed diseases such as frost heave, salt heave, and dissolution.

[0041] Compared with traditional composite geomembrane barrier layer technology, the present application can effectively suppress the "pot lid effect". The bentonite particles can absorb a large amount of water during the hydration process, reducing the accumulation of condensed water under the barrier layer, and alleviating a series of roadbed diseases caused by water and salt migration in saline soil, such as salt swelling, frost swelling, and dissolution.

[0042] The polymer modified bentonite liner layer of the present application is a self-repairing material, which can self-repair when damaged by puncture, thereby ensuring the stability of the liner during long-term service.

[0043] The present application adopts polymer modified bentonite as the anti-seepage material in the liner, which has good salt resistance, durability and corrosion resistance, and can play a good anti-seepage effect during the long-term service of saline soil roadbed.

[0044] The upper and lower layers of three-dimensional geotextile drainage nets of the present application not only have a drainage function, but also replace the gravel protective layer in the traditional composite geomembrane barrier layer in the saline soil roadbed, and play the role of a lining protective layer. The hollow area formed by the geotextile and the drainage net prevents penetration caused by accidental puncture of the bentonite layer by sharp stones.

[0045] In this application, geotextile, modified bentonite particles and drainage net are combined into a new composite liner through a needle punching method and a hot bonding process. The liner itself has good integrity, is easy to transport, and is simple to lay, which greatly improves construction efficiency and labor costs.

[0046] This application can achieve "combination of drainage and blocking". The bentonite granular layer plays an anti-seepage role, blocking the vertical migration of water and salt in the saline soil roadbed. The drainage network can drain excess water to both sides of the roadbed and prevent the bentonite granular layer from being punctured and damaged. This application can effectively suppress the impact of the "pot cover effect", reduce frost heave, salt heave, dissolution and other roadbed diseases caused by uneven water and salt migration and distribution, ensure the quality of road engineering in saline soil areas, and have good social, economic and environmental benefits.

[0047] Example 2

[0048] like Figure 2 As shown, based on Example 1, a roadbed structure provided according to the present invention adopts the new composite lining barrier layer of saline soil roadbed combining dredging and blocking of Example 1, including: a pavement structure layer 9, a roadbed 10, a composite lining barrier layer 11 and an embankment 12 laid in sequence from top to bottom, with slope protection roads 13 and drainage ditches 14 arranged on both sides.

[0049] The slope protection road 13 is symmetrically arranged on both sides of the composite liner insulation layer 11 and the embankment 12. The width of the slope protection road 13 is 3m. The slope protection road 13 completely covers the composite liner insulation layer 11, and the composite liner insulation layer 11 has no exposed surface.

[0050] The drainage ditch 14 is symmetrically arranged on both sides of the slope protection road 13, with a slope of 1:1, and the distance between the drainage ditch 14 and the slope protection road 13 is 2m. The salt water discharged from the composite lining isolation layer 11 flows into the drainage ditch 14 through the slope protection road 13 for discharge, thus ensuring the stability of the roadbed structure.

[0051] The roadbed and slope protection road 13 are filled with coarse-grained soil, and its moisture content is close to the optimal moisture content. Before filling the embankment, the surface salt frost and salt crust should be removed, and the coarse-grained soil should be filled after compaction. The embankment filling can be filled with non-saline soil or chloride-salinated soil, and its moisture content is close to the optimal moisture content.

[0052] After the embankment is completed, the new composite liner is laid. The liner should be laid in rainless and snowless weather. If it rains or snows during construction, plastic film should be used to cover it to prevent the bentonite from hydrating prematurely. The overlap surface of the new composite liner must not have impurities such as sand, stagnant water (including dew) that affect the overlap quality. The roadbed soil should be backfilled and covered and compacted on the day of laying. The partition layer is arranged from the center to both sides and tilted downward, with a slope of 2% to facilitate moisture removal.

[0053] The new composite liner of the present application contains a bentonite particle anti-seepage layer, which can not only prevent the infiltration of surface water, but also block the rise of capillary water and the migration of water and salt under the action of temperature gradient. The three-dimensional geotextile drainage net is bonded to the upper layer of the polymer-modified bentonite liner, which can timely remove the excess water that seeps from the upper part of the roadbed, and improve the ability to cope with extreme climates such as heavy rain. The lower three-dimensional geotextile drainage net can block the rise of capillary water and discharge the water accumulation in the lower part of the barrier layer caused by the "pot lid effect". At the same time, slope protection roads 13 and drainage ditches 14 are designed on both sides of the roadbed to ensure that the roadbed can drain salt and water smoothly during long-term operation, reducing the risk of roadbed settlement caused by water and salt migration and uneven distribution in the saline soil roadbed.

[0054] The present application sets up four layers of geotextiles, which separate the upper three-dimensional geotextile drainage net 2, modified bentonite particles, and the lower three-dimensional geotextile drainage net 6 respectively, thereby filtering water and isolating salt, preventing coarse particles from entering the three-dimensional geotextile drainage net to block the drainage channel, filtering the salt-containing brine in the saline soil to reduce the salt content in the water absorbed by the bentonite during hydration, and ensuring the stability of the anti-seepage performance.

[0055] The structure of three-dimensional geodrainage net air layer - modified bentonite layer - three-dimensional geodrainage net air layer formed in the roadbed of the present application also serves as a cold resistance layer to a certain extent. In addition to being used in saline land areas, it is also applicable to roadbeds in other special land areas affected by temperature and moisture migration.

[0056] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0057] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A new composite liner barrier layer for saline soil roadbed combining dredging and blocking, characterized in that: The composite liner isolation layer (11) comprises, arranged in order from top to bottom: a first layer of non-woven geotextile (1), an upper layer of three-dimensional geotextile drainage net (2), a second layer of non-woven geotextile (3), a polymer-modified bentonite granular layer (4), a third layer of non-woven geotextile (5), a lower layer of three-dimensional geotextile drainage net (6) and a fourth layer of non-woven geotextile (7), wherein the polymer-modified bentonite granular layer (4) is fastened between the second layer of non-woven geotextile (3) and the third layer of non-woven geotextile (5) via needle-punched fibers (8) arranged at intervals.

2. The novel composite liner barrier layer for saline soil roadbed combining dredging and blocking as claimed in claim 1 is characterized in that: The composite liner isolation layer (11) is arranged to tilt downward from the center to both sides, with a slope of 2%.

3. The novel composite liner barrier layer for saline soil roadbed combining dredging and blocking as claimed in claim 1 is characterized in that: The non-woven geotextile of the composite liner insulation layer (11) is made of polypropylene fiber, with a unit area mass of ≥200g / m 2 The unit area mass of the polymer-modified bentonite particle layer (4) is ≥4500 g / m 2 The unit area mass of the composite liner insulation layer (11) is ≥5000 g / m 2 The three-dimensional geotextile drainage net of the composite liner isolation layer (11) is made of polyethylene with a tensile strength of ≥36.5 kN / m.

4. The novel composite liner barrier layer for saline soil roadbed combining dredging and blocking as claimed in claim 1 is characterized in that: The composite liner barrier layer (11) has a tensile strength of ≥1000N / 10cm, a peel strength of ≥60N / 10cm, and a CBR bursting strength of ≥2.5kN.

5. The novel composite liner barrier layer for saline soil roadbed combining dredging and blocking as claimed in claim 1 is characterized in that: A plurality of rows of needle-punched fibers (8) are vertically spaced inside the polymer-modified bentonite granular layer (4), and the polymer-modified bentonite granular layer (4) is fixed between the second layer of non-woven geotextile (3) and the third layer of non-woven geotextile (5) by needle-punching.

6. The novel composite liner barrier layer for saline soil roadbed combining dredging and blocking as claimed in claim 1 is characterized in that: The upper three-dimensional geotextile drainage net (2) is fixed between the first layer of non-woven geotextile (1) and the second layer of non-woven geotextile (3) by using a thermal bonding process.

7. The novel composite liner barrier layer for saline soil roadbed combining dredging and blocking as claimed in claim 1 is characterized in that: The lower three-dimensional geotextile drainage net (6) is fixed between the third layer of non-woven geotextile (5) and the fourth layer of non-woven geotextile (7) by using a thermal bonding process.

8. A roadbed structure, characterized in that: A novel composite liner barrier layer for saline soil roadbed combining dredging and blocking as claimed in any one of claims 1 to 7 is adopted, comprising, laid in order from top to bottom: a pavement structure layer (9), a roadbed (10), the composite liner barrier layer (11) and an embankment (12), with slope protection roads (13) and drainage ditches (14) arranged on both sides.

9. The roadbed structure according to claim 8, characterized in that: The slope protection road (13) is symmetrically arranged on both sides of the composite liner isolation layer (11) and the embankment (12); the width of the slope protection road (13) is 3m; the slope protection road (13) completely covers the composite liner isolation layer (11); and the composite liner isolation layer (11) has no exposed surface.

10. The roadbed structure according to claim 8, characterized in that: The drainage ditch (14) is symmetrically arranged on both sides of the slope protection road (13) with a slope of 1:1, and the distance between the drainage ditch (14) and the slope protection road (13) is 2m.

Images