A device and construction method for saline soil roadbed in seasonal frozen soil areas

Abstract

The present invention discloses a device and construction method for saline soil roadbed in seasonal frozen soil areas, belonging to the technical field of roadbed foundation, to solve the problem that saline soil roadbed in seasonal frozen soil areas is susceptible to frost heave, salt heave and dissolution, and the problem that the cushion layer is thick and difficult to compact when the traditional roadbed gravel soil is used as a permeable barrier layer. The device includes an earthwork roadbed, a heat stabilization facility, and a barrier facility. The barrier facility includes a medium-coarse sand lower protective layer, a modified desert sand barrier layer, and a medium-coarse sand upper protective layer arranged in sequence from bottom to top; the heat stabilization facility includes a bottom roadbed stabilization facility and an upper insulation facility. The bottom roadbed stabilization facility includes a lime soil compaction pile and a lime soil cushion layer arranged in sequence from bottom to top. The method includes the construction of a bottom roadbed stabilization facility, a barrier facility, an earthwork roadbed and an upper insulation facility, and a peripheral water-retaining wall. The present invention can maintain the long-term water, heat, and salt stability of the roadbed through the combination of structure and construction method; the cost is low, the construction process is less, and the maintenance is simple.

Description

Technical Field

[0001] The invention belongs to the technical field of roadbed foundation, and in particular relates to a device and a construction method for a saline soil roadbed in a seasonally frozen soil area. Background Art

[0002] (1) Mechanisms of dissolution, salt expansion and frost expansion of saline soil roadbed in seasonally frozen soil areas:

[0003] The causes of saline soil can be summarized as follows: dry climate, scarce precipitation, strong evaporation, and the parent rock of soil contains more salt. It is particularly widely distributed in the northwestern provinces of my country, and many places in the northwestern provinces are in seasonal frozen soil areas, with an active layer thickness of about 1.5m-2.0m; the soil in the active layer of saline soil roadbed in seasonal frozen soil areas is accompanied by a variety of physical and chemical processes during the freeze-thaw cycle, such as water-salt migration, salt phase change, energy transfer, etc.; after the warm season ends and the cold season begins, the surface begins to freeze within the entire active layer, and the frozen surface develops downward, and water migrates from the bottom to the top toward the frozen surface, accompanied by salt migration. When the groundwater is active, the sodium chloride and sulfur in the soil are affected. Soluble salts such as sodium sulfate have significant dissolving and migration effects, which can easily induce solution subsidence diseases. After entering the warm season, the surface begins to melt, the frozen surface moves downward, and water migrates from top to bottom toward the frozen surface. At the same time, salt migrates. In seasonal frozen soil areas, when the local temperature rises, the solubility of the salt solution gradually increases, and the precipitated crystals begin to melt. With the alternating changes in temperature in seasonal frozen soil areas, the roadbed soil undergoes repeated salt expansion, frost expansion, and solution subsidence processes, and the soil repeatedly swells and loosens, causing surface expansion, slope instability, or deformation and damage to the highway subgrade and pavement. Years of construction experience have shown that the higher the content of salts such as sulfates, the more serious the swelling disease, and the salt expansion and solution subsidence deformation of the soil are irreversible.

[0004] In order to alleviate and prevent frost heave, salt swelling and solution subsidence diseases of saline soil roadbed in seasonally frozen areas, an effective way is to control the water and salt migration, salt phase change, energy transfer and other processes in the soil.

[0005] (2) Measures for controlling water and salt migration in the prior art:

[0006] The traditional method to prevent and control salt swelling and dissolution of saline soil roadbed is to set up a barrier layer, which is divided into an impermeable barrier layer and a permeable barrier layer. The traditional impermeable barrier layer is mainly geotextiles such as waterproof geotextiles and waterproof boards. Geotextiles such as waterproof geotextiles are easily punctured by granular fillers under the action of external loads and temperature loads during the construction rolling stage or the operation stage, which has problems such as affecting the service life. The on-site moisture monitoring data of the roadbed test section of the one-cloth-one-membrane barrier layer shows that the moisture content of the soil at the upper edge of the one-cloth-one-membrane is relatively high, and the moisture content of the surrounding soil is unevenly distributed; the permeable barrier layer is generally made of gravel, aeolian sand, river sand or desert sand and other permeable fillers. The basic principle of the barrier is that the thickness of the barrier layer is greater than or equal to the height of the rising salt capillary water, thereby achieving a barrier effect.

[0007] However, when gravel or river sand is used as a permeable barrier layer, in order to play a barrier role, the paving thickness is relatively large. The capillary water rise height of gravel soil and sand is between 40-110cm, and more fillers are required. It is suitable for sections with a roadbed fill height greater than 1.8m and convenient filler materials. The capillary water rise height of aeolian sand is between 80-90cm. When aeolian sand is used as a permeable barrier layer, the paving thickness is at least 90cm, and there are problems such as difficult to control the compaction degree and large amount of filler required. When silty soil and clay soil are used as a permeable barrier layer, the capillary water rise height is between 200-400cm. If it contains more powder and clay, and there is thin film water between the powder and clay, salt migration will occur, leading to secondary salinization, and the barrier layer will gradually fail. Therefore, the content of powder and clay must be strictly controlled during construction, and the construction is difficult.

[0008] (3) Current status of roadbed insulation and stability in existing technologies:

[0009] In highway projects in permafrost areas or seasonally frozen areas, the insulation method is widely used to prevent frost heave in roadbeds. Laying an insulation layer in the roadbed can effectively reduce the variation range of the roadbed soil temperature field within the active layer, and plays a positive role in preventing and controlling frost heave, water seepage, and thaw settlement.

[0010] In the prior art, the materials used for roadbed insulation mainly include polyurethane (PU) boards, polystyrene foam (EPS) boards and extruded polystyrene foam (XPS) boards. The performance indicators of road engineering insulation materials require that thermal resistance, strength and stiffness must meet certain standards. The thermal resistance and compressive strength of XPS boards are better than those of PU boards and EPS boards, but the mechanical properties of XPS insulation board materials are quite different from those of roadbed fill. The thickness of XPS insulation board is positively correlated with the insulation effect, but excessive thickness of the insulation board will affect the overall stiffness of the roadbed, and may cause problems such as excessive deflection values, making it difficult to promote and apply insulation boards such as XPS.

[0011] The application of slope insulation in highway projects in permafrost areas has been proven to have a counterproductive effect. When the above-mentioned slope insulation materials are used in construction in seasonally frozen areas, it is found that block insulation materials are prone to slide downward, resulting in bulges or misalignment accompanied by local deformation; the thermal conductivity of asphalt expanded perlite, fine-grained soil, and living turf soil is relatively large, and when used as slope insulation materials, their thermal insulation performance is poor.

[0012] Since saline soil roadbeds in seasonal frozen soil areas have to solve the dissolution problems caused by both frost heave and salt heave, the need for roadbed base stability must be taken into account during base treatment. The existing technologies such as water pre-dissolution method, replacement method, dynamic compaction method, and compaction pile method are obviously limited.

[0013] The water pre-dissolution method is suitable for soil layers with small thickness and large permeability coefficient; the effect of the dynamic compaction method in treating saline soil foundations is very unsatisfactory; there are many types of pile foundations in the pile foundation construction process. In saline soil areas, the pore water of the soil is rich in salt solution, with high specific gravity and high viscosity, and it is very difficult and slow to discharge. The drainage period and construction period are long, and the compaction effect of gravel piles is also very unsatisfactory; the chloride ions and sulfates rich in saline soil have a certain corrosive effect on metal materials and concrete. Therefore, driven steel sheet piles, prefabricated square piles, sunken pipe cast-in-place piles, CFG piles, and bored cast-in-place piles are not suitable for roadbed base treatment in saline soil areas.

[0014] Based on the problems in the above background technology, technical personnel in this field have developed and summarized a device and construction method for saline soil roadbed in seasonal frozen soil areas in many places in the northwest during the construction of highway projects with active layer thickness of about 1.5m-2.0m. Summary of the invention

[0015] The purpose of the present invention is to provide a device applied to saline soil roadbed in seasonal frozen soil areas, so as to solve the problems that the roadbed in seasonal frozen soil areas and saline soil areas is susceptible to frost heave, salt heave, dissolution and sinking.

[0016] Another object of the present invention is to provide a construction method for a device applied to saline soil roadbed in seasonal frozen soil areas, so as to solve the problem that the cushion layer is thick and difficult to compact when the traditional roadbed gravel soil is used as a permeable barrier layer.

[0017] In order to solve the above problems, the technical solution of the present invention is:

[0018] A device applied to saline soil roadbed in seasonal frozen soil areas comprises an earth roadbed, a heat stabilization facility and a partition facility, wherein the partition facility comprises a lower protective layer of medium-coarse sand, a modified desert sand partition layer and an upper protective layer of medium-coarse sand arranged in sequence from bottom to top; the heat stabilization facility comprises a bottom roadbed stabilization facility and an upper insulation facility, wherein the bottom roadbed stabilization facility comprises lime soil compaction piles and a lime soil cushion layer arranged in sequence from bottom to top, the lime soil cushion layer is located below the lower protective layer of medium-coarse sand, and the earth roadbed and road surface are laid in sequence above the upper protective layer of medium-coarse sand.

[0019] Furthermore, it also includes hydrothermal monitoring facilities, with one group of hydrothermal monitoring facilities arranged every 10km-50km. The length of each group of hydrothermal monitoring facilities is 1.5m-2.5m, and they are laid along half of the roadbed in the earth roadbed and the medium-coarse sand upper protective layer.

[0020] Furthermore, the horizontal spacing of the hydrothermal probes is 1m, the vertical spacing of the hydrothermal probes is 0.5m, one group of the hydrothermal probes is laid 0.5m beyond the bottom of the lime soil compaction pile, and the remaining groups of hydrothermal probes are only laid in the earth roadbed and the upper protective layer of medium-coarse sand.

[0021] Furthermore, the water and heat monitoring facility includes interconnected thermistor cables and water and heat probes, the thermistor cables are connected to a monitoring device, the monitoring device includes an interconnected information collector and a power supply device, and the power supply device is connected to the thermistor cable.

[0022] Furthermore, modified desert sand waterproof walls are provided on the outside of the lime-soil compaction piles.

[0023] Furthermore, the upper insulation facilities include a bubble-mixed lightweight soil base layer and an insulation berm, the bubble-mixed lightweight soil base layer is located above the earth roadbed and below the road surface, and the insulation berm is located on both sides of the earth roadbed.

[0024] Furthermore, a sand-soil edging area with a trapezoidal cross-section is provided on both sides of the partition facility, and the sand-soil edging area encloses the periphery of the lower protective layer of medium-coarse sand, the modified desert sand partition layer, and the upper protective layer of medium-coarse sand.

[0025] Furthermore, the lime-soil compaction piles adopt plum blossom piles.

[0026] Furthermore, the power supply device includes a solar battery and a solar panel connected to each other, and the solar battery and the solar panel are connected via an inverter.

[0027] A construction method for a device used for saline soil roadbed in seasonal frozen soil areas, characterized in that the method comprises the following steps:

[0028] Step A: Construction of bottom roadbed stabilization facilities:

[0029] Use an excavator to first clear the surface, with a depth of no less than 0.3m, and ensure that the humus soil is removed;

[0030] The lime-soil compaction pile is formed by the pipe sinking method. The pile forming process is as follows: pile driver is in place - steel pipe is driven to the design requirements - material is added - pipe is pulled out - pile is formed - pile top is compacted - heavy hammer is used to seal. After the pile is formed, the base is fully compacted and leveled with a roller and a grader to make the flatness meet the specification requirements.

[0031] The paving thickness is controlled by the benchmark method, and a 30-50cm thick 5% lime soil cushion is laid and compacted layer by layer;

[0032] After the pile is formed, a set of water and heat monitoring facilities are buried in the hole to ensure that the lowest water and heat probe is located 0.5m from the bottom of the lime-soil compaction pile, and then fully compacted and leveled;

[0033] Step B: Construction of partition facilities:

[0034] Fill the edge area with sandy soil in layers;

[0035] Lay a 5cm thick lower protective layer of medium-coarse sand in sequence;

[0036] 3cm-5cm thick modified desert sand barrier layer;

[0037] A 5cm thick upper protective layer of medium-coarse sand, in which water and heat monitoring facilities of corresponding depth are buried during filling;

[0038] Initial compaction in layers, leveling and recompacting, and finally surface rolling;

[0039] Step C: Construction of earthwork roadbed and upper insulation facilities:

[0040] The upper earthwork roadbed and thermal insulation berm of the partition facilities shall be filled in layers, with full width construction and ensuring that the thickness does not exceed 0.3m; after each layer is filled, ensure that the compaction degree meets the requirements of the construction specifications, and bury the water and heat monitoring facilities of the corresponding depth when filling each layer;

[0041] Lay the bubble-mixed lightweight soil base and maintain it for 7 days according to the standard;

[0042] Step D: Construction of external watertight walls:

[0043] Construct modified desert sand watertight walls and use tamping machines to fully compact them;

[0044] Step E: Pavement construction:

[0045] Standards require the construction of pavement.

[0046] The beneficial effects of the present invention are as follows:

[0047] (1) The present invention sets up a barrier facility under the earth roadbed and uses modified desert sand as an impermeable barrier layer. The paving thickness is small, it is easy to compact, and the construction is convenient. It has the characteristics of flexible self-repairing and belongs to a flexible self-repairing impermeable layer, which replaces the traditional thick permeable barrier layer of aeolian sand. The data from the on-site monitoring of the paving of the test section show that the modified desert sand barrier layer can directly block capillary water and the soluble salt dissolved in the capillary water at the same time. The water and salt isolation effect is significant, which solves the problem of dissolution and secondary salinization from the root.

[0048] (2) The heat stabilization facilities of the present invention include bottom roadbed stabilization facilities and upper insulation facilities. The upper insulation facilities are arranged above and around the earth roadbed. In the seasonal frozen soil area in the northwest, the thickness of the active layer is about 1.5m-2.0m. Good insulation facilities can ensure that the earth roadbed below will not be frozen through when the severe winter comes, and solve the problem of frost heave and salt expansion of the lower roadbed after wetting. Bubble mixed lightweight soil is selected as the insulation layer laid above the earth roadbed. Its characteristics are that the density is smaller than that of general concrete, and the strength and stiffness even exceed that of good soil, and Its thermal conductivity, strength and density can be adjusted. Under the condition of meeting the strength and durability requirements, the thermal conductivity can be reduced and the thermal insulation performance can be improved by adjusting the density. The bubble-mixed lightweight soil has a large porosity, a small thermal conductivity, and good earthquake resistance, heat insulation and freeze-thaw resistance. After the bubble-mixed lightweight soil is mixed according to a certain ratio, it has good fluidity, water retention and workability, is easy to construct, and has high initial strength after curing for 7 days. The bubble-mixed lightweight soil belongs to the cement-stabilized aggregate type and can be used for the construction of base and sub-base layers. It has good earthquake resistance, heat insulation and freeze-thaw resistance, and its strength and stiffness meet the requirements.

[0049] In seasonal frozen soil areas, when thermal insulation berms are built and the thickness of the slope thermal insulation berms is greater than the thickness of the active layer, the subgrade temperature outside the widened section will always be positive, which can reduce the range of the active layer outside the widened area, control the occurrence and development of subgrade frost heave, salt heave, and thaw settlement diseases, and avoid soil loosening caused by salt phase change.

[0050] As an upper insulation facility in seasonally frozen soil areas, the combination of bubble-mixed lightweight soil and thermal insulation berms, as shown by data from on-site monitoring during the laying of the test section, can achieve good thermal stabilization effects; the data from on-site testing of the test section was confirmed during construction.

[0051] The bottom roadbed stabilization facilities are laid under the medium-coarse sand lower protective layer. The bottom roadbed stabilization facilities are a combination of lime soil compaction piles and lime soil cushion layers, which are specially designed for the characteristics of saline soil in seasonal frozen soil areas, taking into account factors such as compaction effect, water consumption, and heat supply. The lime soil compaction piles can consume water and release heat during construction, and their volume will expand. The plum blossom-shaped pile group reacts with the underlying foundation soil, absorbs water, expands, and compacts, which can significantly improve the bearing capacity of the base. The large amount of reaction heat released has a positive effect on the thermal stability of the roadbed above. The combined lime soil cushion layer can ensure the absorption of excess capillary water below in later use, and the application effect is good.

[0052] (3) The hydrothermal probes in the hydrothermal monitoring facilities of the present invention can timely detect the hydrothermal status of the earth roadbed and the corresponding positions below it, and collect data for easy monitoring. The whole is powered by solar energy, which is more suitable for the current situation of saline soil sections in the seasonal frozen soil area in the northwest. The laying method adopts half the road width. Considering the freezing depth, it is generally laid at one end of the shady slope, with a group laid every 10km-50km. It can be flexibly adjusted according to the geological conditions of the construction site section. When the geological structure similarity of the construction site section is high, the laying spacing is widened. When the geological structure similarity of the construction site section is low and the situation above the road surface is complicated, the laying spacing is shortened. The hydrothermal monitoring facilities can monitor the hydrothermal conditions inside the roadbed in real time, detect abnormalities in time, and ensure the long-term healthy operation of highways in the seasonal frozen soil area. And a module with a hydrothermal abnormality forecasting function can be installed according to needs to realize intelligent monitoring.

[0053] (4) The method of the present invention emphasizes that the lower protective layer of medium-coarse sand, the modified desert sand barrier layer, and the upper protective layer of medium-coarse sand are surrounded by layered filling sand soil, and the layered construction, laying and compacting are carried out to ensure their stability; at the same time, the earth roadbed and the thermal insulation berm are laid in an integrated manner to ensure the stability of the thermal insulation berm, and the integrated construction process is less and the cost is low; finally, the modified desert sand waterproof wall is built to further prevent the migration of water and salt on both sides of the roadbed, thereby ensuring the stability of the roadbed in all directions.

[0054] (5) The present invention aims at the salt swelling, frost swelling, and dissolution sinking caused by the water-salt migration, salt phase change, and energy transfer processes in the saline soil roadbed in seasonal frozen soil areas. Through the combination of structure and construction method, the present invention can effectively block the upward migration of underground capillary water and soluble salts, and effectively control the salt phase change, energy transfer, and other processes; achieve the effects of water absorption, heat replenishment, and expansion and compaction on the lower base, maintain the long-term water, heat, and salt stability of the roadbed soil; and timely monitor the water and heat conditions of the roadbed; the materials of the components involved are all ordinary geotechnical materials, with low cost, few construction procedures, and simple later maintenance; the construction of the entire facility is carried out simultaneously with the roadbed construction, and the long-term healthy operation effect of the highway after construction is significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a structural schematic diagram of a device applied to saline soil roadbed in seasonally frozen soil areas;

[0056] Figure 2 for Figure 1 Top view of the .

[0057] The accompanying drawings are marked as follows: 1. Bubble-mixed lightweight soil base layer; 2. Insulation berm; 3. Lime-soil cushion layer; 4. Lime-soil compaction piles; 5. Modified desert sand barrier layer; 6. Medium-coarse sand upper protective layer; 7. Medium-coarse sand lower protective layer; 8. Modified desert sand waterproof wall; 9. Sand-grained soil edging area; 10. Thermistor cable; 11. Hydrothermal probe; 12. Monitoring device; 13. Information collector; 14. Power supply device; 15. Road surface; 16. Earthwork roadbed. DETAILED DESCRIPTION

[0058] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0059] like Figure 1-2 As shown, a device applied to saline soil roadbed in seasonal frozen soil areas includes earth roadbed 16, heat stabilization facilities, isolation facilities, and water and heat monitoring facilities.

[0060] Specifically: the partition facility includes a lower protective layer 7 of medium-coarse sand, a modified desert sand partition layer 5, and an upper protective layer 6 of medium-coarse sand, which are arranged in sequence from bottom to top; a sand-grained soil edging area 9 with a trapezoidal cross-section is arranged on both sides of the partition facility, and the sand-grained soil edging area 9 encloses the periphery of the lower protective layer 7 of medium-coarse sand, the modified desert sand partition layer 5, and the upper protective layer 6 of medium-coarse sand.

[0061] Thermal stabilization facilities include bottom-layer roadbed stabilization facilities and upper-layer thermal insulation facilities:

[0062] The bottom roadbed stabilization facilities include lime soil compaction piles 4 and lime soil cushion layer 3 arranged in sequence from bottom to top. The lime soil cushion layer 3 is located below the medium coarse sand lower protective layer 7. The earth roadbed 16 and the road surface 15 are laid in sequence above the medium coarse sand upper protective layer 6. The lime soil compaction piles 4 are plum blossom piles. Modified desert sand waterproof walls 8 are arranged on the outer sides of the lime soil compaction piles 4.

[0063] The upper insulation facilities include a bubble-mixed lightweight soil base layer 1 and an insulation berm 2 . The bubble-mixed lightweight soil base layer 1 is located above the earth roadbed 16 and below the road surface 15 , and the insulation berm 2 is located on both sides of the earth roadbed 16 .

[0064] The water and heat monitoring facility includes a thermistor cable 10 and a water and heat probe 11 connected to each other. The thermistor cable 10 is connected to a monitoring device 12. The monitoring device 12 includes an information collector 13 and a power supply device 14 connected to each other. The power supply device 14 is connected to the thermistor cable 10; the power supply device 14 includes a solar battery and a solar panel connected to each other. The solar battery and the solar panel are connected through an inverter.

[0065] A group of hydrothermal monitoring facilities is arranged every 10km-50km. The length of each group of hydrothermal monitoring facilities is 1.5m-2.5m, and they are laid along half of the roadbed in the earth roadbed 16 and the upper protective layer 6 of medium-coarse sand; the horizontal arrangement spacing of the hydrothermal probes 11 is 1m, and the vertical arrangement spacing of the hydrothermal probes 11 is 0.5m. The laying depth of one group of hydrothermal probes 11 exceeds the bottom of the lime soil compaction pile 4 by 0.5m, and the remaining groups of hydrothermal probes 11 are only laid in the earth roadbed 16 and the upper protective layer 6 of medium-coarse sand.

[0066] The construction method of the above device applied to saline soil roadbed in seasonal frozen soil areas comprises the following steps:

[0067] Step A: Construction of bottom roadbed stabilization facilities:

[0068] Use an excavator to first clear the surface. The depth of the treatment is determined according to the geological conditions of the construction site to ensure that the humus soil is removed. The treatment depth during construction should not be less than 0.3m;

[0069] The lime-soil compaction pile 4 is formed by the pipe sinking method, and the lime-soil compaction pile 4 is arranged into a plum blossom pile. The pile forming process is as follows: the pile driver is in place - the steel pipe is driven to the design requirement - material is added - the pipe is pulled out - pile forming - compaction of the pile top - tamping and sealing with a heavy hammer. After the pile is formed, the base is fully compacted and leveled with a roller and a grader to make the flatness meet the specification requirements;

[0070] The paving thickness is controlled by the benchmark method. A 5% lime soil cushion layer 3 is laid and compacted layer by layer. The paving thickness is determined according to the geological conditions of the construction site. The paving thickness is generally 30cm-50cm.

[0071] After the pile is formed, a set of water and heat monitoring facilities are buried in the hole to ensure that the lowest water and heat probe is located 0.5m from the bottom of the lime-soil compaction pile 4, and then fully compacted and leveled;

[0072] Step B: Construction of partition facilities:

[0073] Layered filling of sandy soil enclosing area 6;

[0074] Lay a 5 cm thick lower protective layer of medium-coarse sand 7 in sequence;

[0075] 3cm-5cm thick modified desert sand barrier layer 5;

[0076] 5cm thick medium-coarse sand upper protective layer 6, when filling this layer, water and heat monitoring facilities of corresponding depth are buried;

[0077] The thickness of the modified desert sand barrier layer 5 is determined according to the geological conditions of the construction site. When the underground capillary water and salt content are high, the paving thickness of the modified desert sand barrier layer 5 is appropriately increased. On the contrary, the paving thickness can reach 3 cm, which can achieve separation and lower the construction cost.

[0078] Initial compaction in layers, leveling and recompacting, and finally surface rolling;

[0079] Step C: Construction of earthwork roadbed and upper insulation facilities:

[0080] The upper earthwork roadbed 16 and thermal insulation berm 2 of the partition facilities are filled in layers, with full width construction, and the thickness of the Matsuura is ensured not to exceed 0.3m; after each layer is filled, the compaction degree is ensured to meet the requirements of the construction specifications, and water and heat monitoring facilities of corresponding depth are buried during each layer of filling;

[0081] Lay the bubble-mixed lightweight soil base 1 and maintain it for 7 days according to the standard;

[0082] Step D: Construction of external watertight walls:

[0083] Construct modified desert sand watertight wall 8 and fully compact it using a tamping machine;

[0084] Step E: Pavement construction:

[0085] The standard requires the construction of road surface 15.

Claims

1. A device for saline soil roadbed in seasonal frozen soil areas, comprising an earth roadbed (16), characterized in that: It also includes isolation facilities, heat stabilization facilities, and water and heat monitoring facilities: The partition facility comprises a medium-coarse sand lower protective layer (7), a modified desert sand partition layer (5), and a medium-coarse sand upper protective layer (6) arranged in sequence from bottom to top; a sand grain soil border area (9) having a trapezoidal cross section is provided on both sides of the partition facility, and the sand grain soil border area (9) encloses the periphery of the medium-coarse sand lower protective layer (7), the modified desert sand partition layer (5), and the medium-coarse sand upper protective layer (6); The thermal stabilization facilities include bottom-layer roadbed stabilization facilities and upper-layer thermal insulation facilities; The bottom roadbed stabilization facilities include lime soil compaction piles (4) and lime soil cushion layers (3) arranged in sequence from bottom to top; modified desert sand water-blocking walls (8) are arranged outside the lime soil compaction piles (4); the lime soil cushion layers (3) are located below the medium-coarse sand lower protective layer (7), and an earth roadbed (16) and a road surface (15) are laid in sequence above the medium-coarse sand upper protective layer (6); The upper thermal insulation facility comprises a bubble-mixed lightweight soil base layer (1) and a thermal insulation berm (2), wherein the bubble-mixed lightweight soil base layer (1) is located above the earth roadbed (16) and below the road surface (15), and the thermal insulation berm (2) is located on both sides of the earth roadbed (16); The hydrothermal monitoring facilities are arranged in groups every 10km-50km, each group of hydrothermal monitoring facilities is 1.5m-2.5m long, and are laid along half of the roadbed in the earth roadbed (16) and the upper protective layer (6) of medium-coarse sand; the hydrothermal monitoring facilities include interconnected thermistor cables (10) and hydrothermal probes (11), the horizontal arrangement spacing of the hydrothermal probes (11) is 1m, the vertical arrangement spacing of the hydrothermal probes (11) is 0.5m, one group of the hydrothermal probes (11) is laid to a depth exceeding the bottom of the lime-soil compaction pile (4) by 0.5m, and the remaining groups of hydrothermal probes (11) are only laid in the earth roadbed (16) and the upper protective layer (6) of medium-coarse sand.

2. The device for use in saline soil roadbed in seasonally frozen soil areas according to claim 1, characterized in that: The thermistor cable (10) is connected to a monitoring device (12), the monitoring device (12) comprising an information collector (13) and a power supply device (14) which are connected to each other, and the power supply device (14) is connected to the thermistor cable (10).

3. A device for use in saline soil roadbed in seasonally frozen soil areas as claimed in claim 1 or 2, characterized in that: The lime-soil compaction pile (4) adopts a plum blossom pile.

4. The device for use in saline soil roadbed in seasonally frozen soil areas as claimed in claim 2, characterized in that: The power supply device (14) comprises a solar cell and a solar panel that are connected to each other, and the solar cell and the solar panel are connected via an inverter.

5. A construction method for a saline soil roadbed device in a seasonally frozen soil region according to claim 1, characterized in that: The method is as follows: Step A: Construction of bottom roadbed stabilization facilities: Use an excavator to first clear the surface, with a depth of no less than 0.3m, and ensure that the humus soil is removed; The lime-soil compaction pile (4) is formed by the pipe sinking method. The pile forming process is as follows: the pile driver is in place - the steel pipe is driven to the design requirement - material is added - the pipe is pulled out - the pile is formed - the pile top is compacted - the pile is sealed by heavy hammer tamping. After the pile is formed, the base is fully compacted and leveled with a roller and a grader to ensure that the flatness meets the specification requirements; The paving thickness is controlled by using the pole method, and a 30-50 cm thick 5% lime soil cushion layer (3) is laid and compacted layer by layer; After the pile is formed, a set of water and heat monitoring facilities are buried in the hole to ensure that the lowest water and heat probe is located 0.5m from the bottom of the lime-soil compaction pile (4), and then fully compacted and leveled; Step B: Construction of partition facilities: Fill the edge area with sand and soil in layers (9); Lay a 5 cm thick lower protective layer of medium-coarse sand (7) in sequence; A 3 cm to 5 cm thick modified desert sand barrier layer (5); A 5 cm thick medium-coarse sand upper protective layer (6), in which water and heat monitoring facilities of corresponding depth are buried during filling; Initial compaction in layers, leveling and recompacting, and finally surface rolling; Step C: Construction of earthwork roadbed and upper insulation facilities: The upper earthwork roadbed (16) and thermal insulation berm (2) of the partition facility are filled in layers, with full width construction and the loose paving thickness being ensured not to exceed 0.3m; after each layer is filled, the compaction degree is ensured to meet the requirements of the construction specification, and water and heat monitoring facilities are buried at the corresponding depth when each layer is filled; Lay the air bubble mixed light soil base (1) and maintain it for 7 days according to the standard; Step D: Construction of external watertight walls: Constructing a modified desert sand watertight wall (8) and fully compacting it using a tamping machine; Step E: Pavement construction: Standards require the construction of pavement.

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