Method and device for restraining deformation of roadbed in permafrost region

Abstract

The invention relates to a roadbed deformation inhibition method and device for a frozen soil region, and the method comprises the following steps: carrying out the geological exploration of the frozen soil region, and obtaining the exploration data; determining an ice melting scheme according to the survey data; according to the ice melting scheme, water heat transfer between the road area of the frozen soil area and other areas is blocked; heating the ice layer of the road area of the frozen soil area to melt the ice layer; water generated by melting the ice layer is drained through the drainage mechanism; a gravel hardcore is matched with an impact rolling mode in a road area of a frozen soil area, and a compact soil layer roadbed is obtained. Compared with the prior art, the method has the advantages of high stability, high construction quality and the like.

Description

Technical Field

[0001] The invention relates to the field of road engineering, and in particular to a method and a device for suppressing roadbed deformation in frozen soil areas. Background Art

[0002] Under the influence of extreme climate, the melting of frozen soil layers (including ice-rich soil layers and soil-containing ice layers) in frozen soil areas leads to roadbed settlement, which greatly affects the driving safety of highways in frozen soil areas. Existing frozen soil roadbed treatment technologies are mainly based on protecting frozen soil. According to the engineering mechanism, they are divided into radiation regulation, convection regulation and heat conduction regulation. These methods mostly protect frozen soil by lowering or maintaining temperature.

[0003] As the high temperature weather intensifies, permafrost continues to degrade, and the permafrost prevention technology with the core idea of ​​protecting permafrost is relatively passive. The pre-thaw settlement technology of high ice content frozen soil roadbed is an effective means of preventing frozen soil roadbed, which is based on the core idea of ​​changing the protection of frozen soil to the treatment of frozen soil to achieve active protection of frozen soil diseases.

[0004] Currently, the commonly used method is to directly melt the ice in the frozen soil roadbed, drain the water and then inject grouting to fill the cavities or cracks formed by the melting of underground ice. However, this technology is difficult to guarantee the melting effect of the ice layer in the frozen soil, and the later grouting is difficult to compact the cavities and cracks, affecting the stability of the roadbed. Summary of the invention

[0005] The purpose of the present invention is to overcome the defect of unstable ice melting effect in the above-mentioned prior art and to provide a method and device for suppressing roadbed deformation in frozen soil areas.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for suppressing roadbed deformation in frozen soil areas comprises the following steps:

[0008] S1: Conduct geological surveys in frozen areas and obtain survey data;

[0009] S2: Determine the ice melting plan based on the survey data;

[0010] S3: According to the ice melting plan, block the water and heat transfer between the road-use area and other areas in the frozen soil area;

[0011] S4: heating and melting the ice in the road area of ​​the frozen soil zone;

[0012] S5: draining the water generated by melting the ice layer in step S4 through a drainage mechanism;

[0013] S6: For roads in frozen soil areas, use a crushed stone cushion layer combined with impact compaction to obtain a dense soil roadbed.

[0014] Furthermore, the method further comprises the following steps:

[0015] S7: Verify the degree of deformation suppression of the roadbed by checking the compaction degree, moisture content and ice distribution of the dense soil layer roadbed.

[0016] Furthermore, the survey data include climate conditions, geological exploration results, and the distribution of underground ice in permafrost areas in different seasons. The ice melting scheme includes heat source, ice melting depth and ice melting speed.

[0017] The second aspect of the present invention is a device for suppressing roadbed deformation in a frozen soil area. The device is used to implement any of the above methods for suppressing roadbed deformation in a frozen soil area. The device includes a continuous wall, an electric heating drain board and a drainage mechanism. The frozen soil area includes an overlying soil layer, an ice-rich soil layer, an ice layer containing soil, and a permafrost layer in sequence from the surface downward. The continuous wall is arranged around the frozen soil area to completely separate the overlying soil layer, the ice-rich soil layer and the ice layer containing soil, and is inserted into the permafrost layer. The electric heating drain board is inserted into and passes through the overlying soil layer and the ice-rich soil layer, stops in the ice layer containing soil, and is exposed from the overlying soil layer. The electric heating drain boards are evenly distributed in the frozen soil area. The drainage mechanism is arranged on the surface of the overlying soil layer to discharge water generated by heating the frozen soil area when the electric heating drain board is working.

[0018] Furthermore, the continuous wall comprises a composite geomembrane and foamed lightweight soil, and the foamed lightweight soil is filled inside the composite geomembrane to form a continuous wall.

[0019] Furthermore, the density of foamed lightweight soil is between 800kg / m 3 ~1200kg / m 3 , compressive strength between 0.3MPa and 20MPa, thermal conductivity between 0.08W / m·K and 0.3W / m·K, bubble volume content greater than 70%; density of composite geomembrane greater than 900g / m 2 , bursting strength greater than 2.6kN, permeability coefficient less than 2×10 -12 cm / s, longitudinal and transverse tensile strength greater than 800N, and corresponding elongation of toughness less than 100%.

[0020] Furthermore, the electrically heated drain plate includes a drain plate, an electric heating wire and a filter cloth. The drain plate is wrapped by at least two layers of filter cloth, and the electric heating wire is arranged between the filter cloths.

[0021] Furthermore, the high temperature tensile strength of the drainage board is greater than 1.6kN / 10cm, and the longitudinal water flow at 100°C is greater than 30cm 3 / s, vertical water flow at normal temperature is greater than or equal to 40cm 3 / s; permeability coefficient of filter cloth k 20 >5.0×10 -3 cm / s; the heating wire can work continuously at a power of 150kW.

[0022] Furthermore, the drainage mechanism includes a sealing ditch, a drainage cushion layer, a sealing membrane and a vacuum pump. The sealing ditch is arranged above the continuous wall to fill the space between the top of the continuous wall and the surface of the overlying soil layer. The drainage cushion layer covers all the electric heating drainage boards. The sealing membrane covers the sealing ditch and the drainage cushion layer and is connected to the vacuum pump to form a sealed environment. When the vacuum pump and the electric heating drainage board are working, the water generated in the heated frozen soil area is pumped into the sealing ditch and the drainage cushion layer through the electric heating drainage board, and then discharged through the vacuum pump.

[0023] Furthermore, the drainage cushion layer is made of medium-coarse sand, the cushion layer thickness is 50 cm, and the permeability coefficient is greater than or equal to 10 -2 cm / s, mud content is less than or equal to 3%, and particle size is 0cm~5cm; three layers of vacuum membrane are arranged, and the vacuum degree under the membrane is maintained above 650mmHg. The vacuum membrane includes vacuum filter tubes under the membrane. The spacing between the vacuum filter tubes under the membrane is 5m, the filter tube diameter is 50mm, and it is buried in the middle of the drainage cushion layer.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) The present invention controls the thawing and settling of frozen soil by measuring and blocking frozen soil areas, thereby protecting the quality of the roadbed and avoiding the impact on the frozen soil in the surrounding areas of the road. The present invention removes moisture from the frozen soil road section through the pre-thawing, drainage, and compaction deformation processes, reduces the impact of later water vapor exchange on the roadbed, avoids the re-infiltration of water vapor, and ensures that the roadbed has a longer stable period, making it easier to control the construction quality.

[0026] 2) The present invention uses the physical isolation and penetration barrier of the composite geomembrane to block the lateral water seepage and reduce the water vapor infiltration. It uses foam lightweight soil backfill to form a closed continuous wall, which effectively prevents heat conduction, eliminates the influence of heat exchange, and ensures the deformation stability of the roadbed area. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a schematic diagram of a method flow of an embodiment of the present invention.

[0028] Figure 2 It is a schematic diagram of the structure of the electric heating drainage board of the present invention.

[0029] Figure 3 It is a top view of the layout of the device of the present invention.

[0030] Figure 4 It is a detailed layout diagram of the device of the present invention.

[0031] Figure 5 Schematic diagram of the structure of the continuous wall.

[0032] Figure 6The following is a detailed flow chart of the method practice process.

[0033] Explanation of the marks in the figure: 1. Continuous wall, 11. Composite geomembrane, 12. Foam lightweight soil, 2. Electric heating drainage board, 21. Drainage board, 22. Electric heating wire, 23. Filter cloth, 31. Overlying soil layer, 32. Ice-rich soil layer, 33. Soil-containing ice layer, 34. Permafrost, 41. Sealing ditch, 42. Drainage cushion layer, 43. Vacuum membrane, 44. Vacuum pump. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0035] The present invention is a method and device for suppressing roadbed deformation in frozen soil areas. Figure 1 As shown, the following steps are included:

[0036] S1: Conduct geological surveys in frozen areas and obtain survey data;

[0037] S2: Determine the ice melting plan based on the survey data;

[0038] S3: According to the ice melting plan, block the water and heat transfer between the road-use area and other areas in the frozen soil area;

[0039] S4: heating and melting the ice in the road area of ​​the frozen soil zone;

[0040] S5: draining the water generated by melting the ice layer in step S4 through a drainage mechanism;

[0041] S6: For roads in frozen soil areas, use a crushed stone cushion layer combined with impact compaction to obtain a dense soil roadbed.

[0042] In order to verify the inhibitory effect of the inhibitory method of the present invention, verification can be performed by the following steps:

[0043] S7: Verify the degree of deformation suppression of the roadbed by checking the compaction degree, moisture content and ice distribution of the dense soil layer roadbed.

[0044] At the same time, if Figure 4As shown, the present invention proposes a device for suppressing roadbed deformation in a frozen soil area, comprising a continuous wall 1, an electric heating drainage board 2 and a drainage mechanism. The frozen soil area includes an overlying soil layer 31, an ice-rich soil layer 32, an ice layer containing soil 33, and a permafrost layer 34 from the surface downward. The continuous wall 1 is arranged around the frozen soil area, completely separating the overlying soil layer 31, the ice-rich soil layer 32 and the ice layer containing soil 33, and inserted into the permafrost layer 34. The electric heating drainage board 2 is inserted into and passes through the overlying soil layer 31 and the ice-rich soil layer 32, and stops in the ice layer containing soil 33, while being exposed from the overlying soil layer 31. The electric heating drainage board 2 is evenly distributed in the frozen soil area. The drainage mechanism is arranged on the surface of the overlying soil layer 31, and is used to discharge water generated by heating the frozen soil area when the electric heating drainage board 2 is working.

[0045] like Figure 6 As shown, the specific implementation process of the present invention is:

[0046] Combined with local meteorological conditions and geological exploration results, determine the distribution of ground ice in frozen soil layers in different seasons, including ice-rich soil layer 32, ice-containing soil layer 33 and permafrost layer 34. Among them, meteorological conditions can refer to local meteorological station data, and geological exploration can be carried out by geophysical methods such as high-density electrical method and transient Rayleigh wave method to explore the geological conditions of the area to be reinforced.

[0047] According to the distribution of underground ice in the frozen ground layer in different regions in step S1, the heat source, ice melting depth and ice melting speed of the melting treatment are determined. Among them, the ice melting depth is set to a certain distance below the permafrost layer 34, and the ice melting speed is adjusted by adjusting the power of the heat source resistance wire 12, the spacing of the electric heating drainage board 1, and the number of circles of the resistance wire 12.

[0048] The continuous wall 1 is designed to block the water and heat exchange between the roadbed reinforcement area and other areas, and provide a closed boundary for the vacuum preloading consolidation drainage S5. Figure 5 As shown, the composite geomembrane-foam lightweight soil continuous wall 1 includes a composite geomembrane 11 and a continuous wall 12 formed by foam lightweight soil backfill; the composite geomembrane 11 blocks lateral water penetration by physically isolating water penetration; the continuous wall 12 formed by foam lightweight soil backfill is formed by foam lightweight soil backfill, and foam lightweight soil has self-leveling, compaction and thermal insulation properties. The use of foam lightweight soil to backfill trenches can form a closed continuous wall, which is easy to construct and can effectively prevent heat conduction; during the construction of the composite geomembrane-foam lightweight soil continuous wall 1, the boundary and depth of the area to be reinforced are determined by setting the parameters of S1 and S2, and the composite geomembrane 11 is laid after excavation, and then foam lightweight soil is backfilled to form the continuous wall 12 formed by foam lightweight soil backfill. The materials of the composite geomembrane-foam lightweight soil continuous wall 1 should meet the following requirements: the density of the foam lightweight soil should be between 800kg / m 3 ~1200kg / m 3The compressive strength is between 0.3MPa and 20MPa, the thermal conductivity is between 0.08W / m·K and 0.3W / m·K, the bubble volume content is greater than 70%; the density of the composite geomembrane is greater than 900g / m 2 , bursting strength (CBR) greater than 2.6kN, permeability coefficient less than 2×10 -12 cm / s, longitudinal and transverse tensile strength is greater than 800N, and the corresponding elongation of toughness is less than 100%.

[0049] After the construction of the continuous wall 1 is completed, the electric heating drainage board 2 is used to melt the ice in the frozen ground layer; the electric heating drainage board 2 can provide a heat source for melting the frozen ground layer on the one hand, and provide a drainage channel for vacuum preloading on the other hand. Figure 2 As shown, the electric heating drain plate 2 includes a drain plate 21, an electric heating wire 22 and a filter cloth 23. The drain plate 21 is wrapped by two layers of filter cloth 23, and the electric heating wire 22 is arranged between the filter cloth 23. The drain plate 21 should be made of high temperature resistant material, and the high temperature tensile strength is required to be greater than 1.6kN / 10cm, and the longitudinal water flow at 100°C should be greater than 30cm 3 / s, vertical water flow at normal temperature is not less than 40cm 3 / s, folded 5 times without breaking; permeability coefficient k of filter cloth 13 20 >5.0×10 -3 cm / s; the heating wire 12 should be able to work continuously under the working condition of 150kW power. Figure 3 As shown, the electric heating drainage plates 2 are evenly arranged in the road area to achieve a uniform heating effect and fully melt the ice layer.

[0050] The drainage mechanism includes a sealing ditch 41, a drainage cushion layer 42, a sealing membrane 43 and a vacuum pump 44. The sealing ditch 41 is arranged above the continuous wall 1, filling the space between the top of the continuous wall 1 and the surface of the overlying soil layer 31. The drainage cushion layer 42 covers all the electric heating drainage boards 2. The sealing membrane 43 covers the sealing ditch 41 and the drainage cushion layer 42, and is connected to the vacuum pump 44 to form a sealed environment. When the vacuum pump 44 and the electric heating drainage board 2 are working, the water generated in the heated frozen soil area is pumped out through the electric heating drainage board 2 into the sealing ditch 41 and the drainage cushion layer 42, and then discharged through the vacuum pump 44. Among them, the material of the drainage cushion layer 42 is medium-coarse sand, and the cushion layer thickness is 50cm. The medium-coarse sand cushion layer is required to have good permeability, and the permeability coefficient is greater than or equal to 10 -2 cm / s, mud content is less than or equal to 3%, and particle size is 0cm~5cm; vacuum membrane 43 is set with three layers, and the vacuum degree under the membrane is maintained at more than 650mmHg. The vacuum membrane 43 includes a vacuum filter tube under the membrane, and the spacing between the vacuum filter tubes under the membrane is 5m, the filter tube diameter is 50mm, and it is buried in the middle of the drainage cushion layer 2. Before the drainage mechanism works, a vacuum degree test is required. After the vacuum degree reaches the construction requirements, the drainage mechanism is started to discharge the water generated by the melting of the ice layer.

[0051] The crushed stone cushion layer is combined with impact rolling to further reinforce and compact the drainage cushion layer 42. Under the action of mechanical impact force, soil particles are rearranged, which will significantly improve the bearing capacity and stability of the soil.

[0052] Large-scale detection can be carried out through geophysical exploration methods, such as high-density electrical method and transient Rayleigh wave method, and comprehensive evaluation can be carried out in combination with drilling results, while the construction quality of the continuous wall 1 can be tested.

[0053] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for suppressing roadbed deformation in frozen soil areas. It is characterized in that The following steps are involved: S1: Conduct geological surveys in frozen areas and obtain survey data; S2: Determine the ice melting plan based on the survey data; S3: According to the ice melting plan, block the water and heat transfer between the road-use area and other areas in the frozen ground area; S4: heating and melting the ice in the road area of ​​the frozen soil zone; S5: draining the water generated by melting the ice layer in step S4 through a drainage mechanism; S6: For roads in frozen soil areas, use a crushed stone cushion layer combined with impact compaction to obtain a dense soil roadbed.

2. A method for suppressing roadbed deformation in frozen soil areas according to claim 1, It is characterized in that The following steps are also included: S7: Verify the degree of subgrade deformation suppression by examining the compaction degree, moisture content and ice distribution of the dense soil subgrade.

3. A method for suppressing roadbed deformation in frozen soil areas according to claim 1, It is characterized in that The survey data include climate conditions, geological survey results, and underground ice distribution in frozen soil areas in different seasons. The ice melting scheme includes heat source, ice melting depth, and ice melting speed.

4. A device for suppressing roadbed deformation in frozen soil areas, It is characterized in that The device is used to implement a method for suppressing roadbed deformation in a frozen soil area as described in any one of claims 1 to 3, the device comprising a continuous wall (1), an electric heating drainage board (2) and a drainage mechanism, the frozen soil area comprising an overlying soil layer (31), an ice-rich soil layer (32), an ice layer containing soil (33), and a permafrost layer (34) from the surface downward in sequence, the continuous wall (1) is arranged around the frozen soil area, completely separating the overlying soil layer (31), the ice-rich soil layer (32) and the ice layer containing soil (33), and inserted into the permafrost layer (34), the electric heating drainage board (2) is inserted into and passes through the overlying soil layer (31) and the ice-rich soil layer (32), stops in the ice layer containing soil (33), and is exposed from the overlying soil layer (31), the electric heating drainage board (2) is evenly distributed in the frozen soil area, the drainage mechanism is arranged on the surface of the overlying soil layer (31), and is used to discharge water generated by the electric heating drainage board (2) heating the frozen soil area when it is working.

5. A device for suppressing roadbed deformation in frozen soil areas according to claim 4, It is characterized in that The continuous wall (1) comprises a composite geomembrane (11) and foamed lightweight soil (12), wherein the foamed lightweight soil (12) is filled inside the composite geomembrane (11) to form a continuous wall.

6. A device for suppressing roadbed deformation in frozen soil areas according to claim 5, It is characterized in that The density of the foamed lightweight soil (12) is between 800 kg / m 3 ~1200kg / m 3 , compressive strength between 0.3MPa and 20MPa, thermal conductivity between 0.08W / m·K and 0.3W / m·K, bubble volume content greater than 70%; the density of the composite geomembrane (11) is greater than 900g / m 2 , bursting strength greater than 2.6kN, permeability coefficient less than 2×10 -12 cm / s, longitudinal and transverse tensile strength greater than 800N, and corresponding elongation of toughness less than 100%.

7. A device for suppressing roadbed deformation in frozen soil areas according to claim 4, It is characterized in that The electrically heated drain plate (2) comprises a drain plate (21), an electric heating wire (22) and a filter cloth (23); the drain plate (21) is wrapped by at least two layers of filter cloth (23), and the electric heating wire (22) is arranged between the filter cloths (23).

8. A device for suppressing roadbed deformation in frozen soil areas according to claim 7, It is characterized in that The high-temperature tensile strength of the drainage board (21) is greater than 1.6 kN / 10 cm, and the longitudinal water flow at 100° C. is greater than 30 cm 3 / s, vertical water flow at normal temperature is greater than or equal to 40cm 3 / s; the permeability coefficient k of the filter cloth (23) 20 >5.0×10 -3 cm / s; the heating wire (22) can work continuously under a power of 150 kW.

9. A device for suppressing roadbed deformation in frozen soil areas according to claim 4, It is characterized in that The drainage mechanism comprises a sealing groove (41), a drainage cushion layer (42), a sealing membrane (43) and a vacuum pump (44); the sealing groove (41) is arranged above the continuous wall (1) to fill the space between the top of the continuous wall (1) and the surface of the overlying soil layer (31); the drainage cushion layer (42) covers the entire electric heating drainage board (2); the sealing membrane (43) covers the sealing groove (41) and the drainage cushion layer (42) and is connected to the vacuum pump (44) to form a sealed environment; when the vacuum pump (44) and the electric heating drainage board (2) are working, water generated in the heated frozen soil area is pumped out through the electric heating drainage board (2) into the sealing groove (41) and the drainage cushion layer (42), and then discharged through the vacuum pump (44).

10. A device for suppressing roadbed deformation in frozen soil areas according to claim 9, It is characterized in that The drainage cushion layer (42) is made of medium-coarse sand, has a cushion thickness of 50 cm, and a permeability coefficient greater than or equal to 10. -2 cm / s, mud content is less than or equal to 3%, and particle size is 0cm~5cm; the vacuum membrane (43) is arranged in three layers, and the vacuum degree under the membrane is maintained at more than 650mmHg. The vacuum membrane (43) includes a vacuum filter tube under the membrane, and the spacing between the vacuum filter tubes under the membrane is 5m, the filter tube diameter is 50mm, and it is buried in the middle of the drainage cushion layer (2).

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