Frozen soil road foundation structure and construction method thereof

Abstract

The invention relates to a frozen soil road foundation structure and a construction method thereof, belongs to the technical field of frozen soil area road foundation enhancement, and solves the problems of frozen soil degradation, road foundation stability reduction and the like caused by external water entering a foundation in the prior art. The invention discloses a frozen soil road foundation structure. The frozen soil road foundation structure comprises a steel sheet pile retaining wall and a foundation main body structure, the steel sheet pile retaining wall is vertically arranged on the inner side of the edge of the cross section of a roadbed in the runoff upstream direction, the bottom of the steel sheet pile retaining wall is inserted into a permanent frozen soil layer, the edge of the tamping layer is connected with the downstream side of the steel sheet pile retaining wall, and the upper surface of the tamping layer is flush with the earth surface. By means of the structure, external incoming water is effectively obstructed, especially underground runoff is obstructed, the problems of frozen soil degradation, foundation stability reduction and the like caused by the external runoff are avoided, the phenomenon of differential settlement of a roadbed is relieved and even avoided, the pavement condition of the frozen soil road is effectively improved, and the service life of the frozen soil road is effectively prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of frozen soil highway foundation reinforcement, and in particular to a frozen soil highway foundation structure and a construction method thereof. Background Art

[0002] Soil is composed of various granular minerals, organic matter, water, air, microorganisms, etc. Under the environment of global warming and the gradual degradation of permafrost areas, there are many difficulties in building roads in permafrost areas. Among them, the intrusion of external water into the road foundation accelerates the degradation of permafrost and reduces the stability of the road foundation, resulting in uneven settlement of the road surface, which seriously affects the road surface quality, service life and driving safety of vehicles on permafrost roads.

[0003] Most of the methods of water retaining for frozen soil highway subgrades currently used are to retain water or drain water on the ground, which can play a certain role in blocking the surface runoff water. For example, patent CN215518599U proposes a highway water retaining strip for protecting the roadbed, which uses a longitudinal bottom plate fixed to the edge of the highway, a water retaining plate is constructed on one side of the bottom plate along the longitudinal direction of the bottom plate, and a boss protruding from the upper surface of the bottom plate is constructed on the other side of the bottom plate along the longitudinal direction of the bottom plate, and a guide groove is formed between the water retaining plate and the boss, which can improve the effect of water retaining on the ground.

[0004] The existing technology does not consider simultaneously blocking surface runoff water and water flow in the soil (underground runoff) from entering the highway foundation in permafrost areas. Currently, there is no mature method that can effectively slow down or even avoid erosion and damage to the highway foundation caused by external water in permafrost areas. Summary of the invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a frozen soil highway foundation structure and a construction method thereof, so as to solve the problems in the prior art of external water entering the highway foundation leading to frozen soil degradation and decreased road foundation stability.

[0006] The present invention discloses a frozen soil highway foundation structure, which comprises a steel sheet pile retaining wall 5 and a foundation main structure; the foundation main structure comprises a road surface 8, a roadbed 6, a compacted layer 7, and a permafrost layer 10 from top to bottom;

[0007] The steel sheet pile retaining wall 5 is vertically arranged on the inner side of the edge of the cross section of the roadbed 6 along the upstream direction of the runoff, and the bottom is inserted into the permafrost layer 10. The edge of the compacted layer 7 is connected to the backwater side of the steel sheet pile retaining wall 5, and the upper surface of the compacted layer 7 is flush with the ground surface 9.

[0008] Specifically, the top of the steel sheet pile retaining wall 5 is flush with the ground surface 9 or slightly higher than the ground surface 9 and lower than the height of the corresponding position of the roadbed 6; both sides of the roadbed 6 are slope structures.

[0009] Specifically, a drainage channel 4 is provided along the extension direction of the highway on the outer side of the cross-section edge of the roadbed 6 .

[0010] Specifically, the bottom of the steel sheet pile retaining wall 5 is inserted into the permafrost layer 10 2-5 m.

[0011] Specifically, the steel sheet pile retaining wall 5 is formed by splicing one or more of U-shaped, Z-shaped, O-shaped, I-shaped cold-bent steel sheet piles or hot-rolled Larsen steel sheet piles; a locking structure is provided at the joint of the steel sheet piles 1; the steel sheet piles 1 have a thickness of 3 to 16 mm, a width of 300 to 900 mm, and a length of 4 to 16 meters.

[0012] Specifically, a waterproof filler 2 is provided in the internal gap of the lock structure at the joint of the steel sheet piles 1 of the steel sheet pile retaining wall 5; and a waterproof cloth 3 is provided on one side of the steel sheet pile 1 retaining wall along the water-facing direction of the runoff.

[0013] The present invention also discloses a construction method applicable to the foundation structure, which specifically comprises the following steps:

[0014] S1 Exploration and design: Measure the soil moisture content on both sides of the road, explore the surface 9 and underground runoff directions, determine the protection area of ​​the steel sheet pile retaining wall 5, and design the waterproof system structure according to the runoff characteristics in the protection area;

[0015] S2 Road surface cleaning: remove the topsoil, grass, all garbage, shrubs, trees, stones, waste and other debris within the scope of roadbed 6;

[0016] S3 steel sheet pile driving: prepare steel sheet piles 1 of appropriate specifications, drive the steel sheet piles 1 into predetermined positions according to pre-designed conditions, and assemble them into steel sheet pile retaining walls 5;

[0017] S4 anti-seepage treatment and compaction: After the steel sheet pile retaining wall 5 is sealed and anti-corrosion treated, the foundation is compacted to obtain a compacted layer 7;

[0018] S5 roadbed backfilling and road surface compaction: backfill the roadbed 6 and compact the road surface 8 on the compacted layer 7 to obtain a frozen soil highway foundation structure with a water retaining function.

[0019] Specifically, the waterproof system structure design in step S1 includes:

[0020] (1) When both surface runoff and underground runoff exist in the protection area, a drainage channel 4 is set up on the water-facing surface, a water culvert is set up at a suitable location on the highway, and a steel sheet pile retaining wall 5 is combined to realize a comprehensive foundation water retaining protection system;

[0021] (2) When only underground runoff exists in the protection area, a steel sheet pile retaining wall 5 is set in the runoff area and a suitable channel is set for the underground runoff by means of bridging, bridge connection or underground culvert at a suitable location.

[0022] Specifically, the sealing treatment in step S4 includes filling and sealing the gaps at the joints of the steel sheet piles 1 with a waterproof filler 2 .

[0023] Specifically, the anti-corrosion treatment in step S4 includes:

[0024] When the steel sheet pile 1 is made of ferritic stainless steel and the frozen soil contains chloride ions, a sacrificial anode anti-corrosion measure is adopted;

[0025] When the steel sheet pile 1 is made of low alloy low temperature corrosion resistant steel or high quality carbon structural steel, surface coating technology or sacrificial anode anti-corrosion measures are adopted.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] 1. The present invention effectively prevents underground runoff from entering the highway foundation and causing the degradation of frozen soil under the highway foundation. It is essentially different from the prior art that can only block surface water. It effectively slows down or even prevents the uneven settlement of frozen soil highway foundation, which helps to improve the road quality and vehicle driving safety.

[0028] The present invention sets a sealed steel sheet pile retaining wall in the water-facing direction along the highway direction and close to the runoff water side (generally the side with a higher altitude, such as a hillside), and inserts the bottom end of the retaining wall under the permafrost layer. The steel sheet pile retaining wall and the permafrost layer jointly form a semi-enclosed water retaining space, so that the main structure of the highway foundation is completely isolated from external water (especially underground runoff), avoiding external water from entering the main structure of the foundation due to infiltration and disturbing the frozen soil at the junction of the compacted layer and the permafrost layer, slowing down or even avoiding the degradation of the frozen soil layer at the bottom of the main structure of the foundation, and greatly improving the stability of the road foundation.

[0029] It is worth explaining that the side along the highway and close to the runoff water does not necessarily refer to only one side of the highway. For example, when the highway extends along a valley, the runoff water direction may exist on both sides of the highway at the same time. At this time, it is necessary to set up steel sheet pile retaining walls on both sides of the highway to prevent external water from entering the highway foundation.

[0030] 2. Even better, a drainage channel is set up along the extension direction of the highway on the outside of the edge of the roadbed cross section. The drainage channel can drain the surface runoff (ground water) and the underground runoff (underground water) overflowing to the surface due to the blocking of the steel sheet pile retaining wall more quickly, and divert the external water away from the road foundation to avoid damage to the roadbed caused by long-term immersion;

[0031] More preferably,

[0032] (1) When both surface runoff and underground runoff exist in the protection area, drainage channels are set up on the water-facing surface, water culverts are set up at appropriate locations on the highway, and a comprehensive foundation water retaining protection system is implemented in combination with steel sheet pile retaining walls;

[0033] (2) When only underground runoff exists in the protection area, a steel sheet pile protection wall is set up in the runoff area and a suitable channel is set up for the groundwater runoff by means of bridging, bridge connection or underground culvert at a suitable location.

[0034] Structural designs such as water-passing culverts, spans, bridges or underground culverts can better and faster drain external water whose flow direction has been changed by the highway itself and the steel sheet pile retaining wall. On the one hand, it can better protect the highway subgrade, and on the other hand, it can also help reduce the impact of highway construction on the ecological environment, so as to avoid the blockage of water in some areas due to highway obstruction, which in turn leads to negative environmental impacts such as vegetation withering and animal population shrinkage.

[0035] 3. The construction method provided by the present invention is relatively simple and can be realized by relying on existing construction technology and equipment. It has been tested on a small scale in some frozen soil areas of the Qinghai-Tibet Plateau. The construction method is feasible and has achieved good results (see the embodiments), and is suitable for road construction and highway foundation waterproofing in large frozen soil areas.

[0036] 4. The present invention performs anti-penetration and anti-corrosion treatment on the steel sheet pile retaining wall (or steel sheet piles), which on the one hand effectively improves the waterproof and anti-corrosion properties of the steel sheet pile retaining wall, and on the other hand significantly increases the service life of the steel sheet pile retaining wall. It is worth noting that the service life of the steel sheet pile retaining wall should not be increased indefinitely, that is, the anti-corrosion treatment does not seek to pursue excessively high anti-corrosion performance, but makes the service life of the steel sheet pile retaining wall as close as possible to the service life of the road.

[0037] More specifically, the service life of the steel sheet pile retaining wall should be made as slightly longer than the service life of the road as possible; on the one hand, it avoids excessive costs caused by performance overflow (mainly referring to anti-corrosion performance), so that when the road is renovated, the steel sheet pile retaining wall also reaches its retirement time and can be replaced simultaneously with the road renovation; on the other hand, it reduces maintenance and replacement of the steel sheet pile retaining wall during its service life, and reduces maintenance costs as much as possible, even close to 0, while meeting the protection performance requirements.

[0038] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0040] Figure 1 This is a schematic diagram of the steel sheet pile retaining wall structure;

[0041] Figure 2 The schematic diagram of a possible implementation scheme of a frozen soil highway foundation structure (with water coming from one side).

[0042] Reference numerals:

[0043] 1-Steel sheet piles; 2-Waterproof filler; 3-Waterproof cloth; 4-Drainage ditch; 5-Steel sheet pile retaining wall; 6-Roadbed; 7-Compacted layer; 8-Road surface; 9-Ground surface; 10-Permafrost layer. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0045] At present, during the geological exploration and highway construction in frozen soil areas, especially in plateau frozen soil areas, it has been found that surface runoff and underground runoff will enter the main structure of the highway foundation through infiltration and other means. On the one hand, it will cause the moisture content of the compacted layer and the roadbed to be disturbed, resulting in a decrease in the stability of the road foundation. On the other hand, the above-mentioned external water (including surface runoff and underground runoff), especially underground runoff, will disturb the surface of the permafrost layer, causing the frozen soil interface to degrade and the frozen soil layer to descend, which will lead to a significant decrease in the supporting force of the bottom layer of the road, and then cause uneven settlement of the road, forming a "washboard" road condition, seriously affecting the road quality and driving safety.

[0046] In the existing technology, on the one hand, the main focus is on the drainage of surface runoff; on the other hand, the existing drainage or ground water retaining technology is difficult to apply to the harsh frozen soil environment, and cannot achieve effective protection for the road foundation (mainly referring to the compacted layer, roadbed, etc.); analyzing the reasons, it is found that the drainage method focusing on surface runoff cannot effectively block and discharge the water on the ground and underground at the same time, and the simple ground water retaining does not fully consider the special environment of the frozen soil area and the problems of frozen soil degradation.

[0047] Based on the above problems and analysis, the present invention discloses a frozen soil highway foundation structure, which includes a steel sheet pile retaining wall and a foundation main structure; the foundation main structure is a road surface, a roadbed, a compacted layer, and a permafrost layer from top to bottom;

[0048] The steel sheet pile retaining wall is vertically arranged on the inner side of the edge of the roadbed cross section along the upstream direction of the runoff, and the bottom is inserted into the permafrost layer. The edge of the compacted layer is connected to the backwater side of the steel sheet pile retaining wall, and the upper surface of the compacted layer is flush with the ground surface.

[0049] The present invention effectively prevents underground runoff from entering the highway foundation and causing degradation of the frozen soil under the highway foundation. It is essentially different from the prior art that can only block surface water. It effectively slows down or even prevents the uneven settlement of the frozen soil highway foundation, and helps to improve the road quality and vehicle driving safety.

[0050] The present invention sets a sealed steel sheet pile retaining wall in the water-facing direction along the highway direction and close to the runoff water side (generally the side with a higher altitude, such as a hillside), and inserts the bottom end of the retaining wall under the permafrost layer. The steel sheet pile retaining wall and the permafrost layer jointly form a semi-enclosed water retaining space, so that the main structure of the highway foundation is completely isolated from external water (especially underground runoff), avoiding external water from entering the main structure of the foundation due to infiltration and disturbing the frozen soil at the junction of the compacted layer and the permafrost layer, slowing down or even avoiding the degradation of the frozen soil layer at the bottom of the main structure of the foundation, and greatly improving the stability of the road foundation.

[0051] It is worth explaining that the side along the highway and close to the runoff water does not necessarily refer to only one side of the highway. For example, when the highway extends along a valley, the runoff water direction may exist on both sides of the highway at the same time. At this time, it is necessary to set up steel sheet pile retaining walls on both sides of the highway to prevent external water from entering the highway foundation.

[0052] It is worth emphasizing that the water retaining structure described in the present invention is not for reducing the moisture content in the road foundation as much as possible, but for keeping the moisture content in the road foundation as stable as possible. Because precipitation in the natural environment is uncontrollable, and unless encountering extreme geological disasters (heavy precipitation that is rare in a century, etc.), the damage of natural precipitation to the road foundation is very limited, and relatively timely and effective drainage can be achieved based on the natural drainage capacity of soil and surface vegetation (surface runoff, soil infiltration, etc.); and the soil (including frozen soil) itself contains a certain amount of moisture, and the moisture also provides a part of the supporting force. If the moisture content in the road foundation is excessively reduced, it is required to isolate all external water, such as natural precipitation, which will reduce the supporting force and stability of the road foundation. One of the important effects of the present invention is to reduce the impact of external disturbances (especially underground runoff) on the moisture content and distribution within the road foundation, thereby improving the stability of the road foundation.

[0053] Specifically, the steel sheet pile retaining wall is vertically arranged 0.1 to 1 m inside the edge of the cross section of the roadbed along the water-facing direction of the runoff, for example, 0.1, 0.2, 0.5, 0.5, 1.0 m. The slope ratio of a general frozen soil road slope is 1:1 to 1:1.5, and the above range can ensure that the steel sheet pile retaining wall is below 1 / 2 of the height of the road slope; more preferably, the steel sheet pile retaining wall is arranged close to the edge of the cross section of the roadbed, for example, 0.1 to 0.3 m, so as to prevent the steel sheet pile retaining wall from being too close to the road surface and affecting the bearing capacity of the road surface.

[0054] Specifically, the top of the steel sheet pile retaining wall is flush with the ground surface or slightly higher than the ground surface and lower than the height of the corresponding position of the roadbed; the two sides of the roadbed are slope structures. The top of the steel sheet pile retaining wall must be at least flush with the ground surface to prevent external water from penetrating into the compacted layer through the gap between the ground surface and the top of the steel sheet pile retaining wall; in addition, the top of the steel sheet pile retaining wall should not leak out of the corresponding height of the ground surface or the roadbed, because if it is exposed, the steel sheet piles will come into contact with the atmosphere / air and then be corroded by the atmosphere, affecting the service life of the steel sheet piles. The two sides of the roadbed are slope structures, which help to improve the stability of the roadbed.

[0055] Preferably, a drainage channel is also provided outside the edge of the roadbed cross section along the extension direction of the highway. The drainage channel is provided outside the edge of the roadbed cross section, and the drainage channel can drain the surface runoff (ground water) and the underground runoff (underground water) overflowing to the surface due to the blocking of the steel sheet pile retaining wall more quickly, and guide the external water away from the road foundation range to avoid damage to the roadbed caused by long-term immersion;

[0056] Specifically, the bottom of the steel sheet pile retaining wall is inserted into the permafrost layer by 2 to 5 meters. The depth of the bottom of the steel sheet pile retaining wall inserted into the permafrost layer should not be too deep or too shallow; if the depth is too shallow, during the service period of the steel sheet pile retaining wall, when the permafrost layer gradually degrades due to various reasons, the steel sheet pile retaining wall will become loose, tilted, and other defects, affecting the water retaining effect; if the depth is too deep, it will lead to a substantial increase in construction costs, and may even cause equipment damage due to reasons such as excessive strength of the permafrost layer and overheating of the equipment.

[0057] It is worth noting that the gradual degradation or intermittent softening of the permafrost layer is not entirely caused by external water. For example, global warming and seasonal changes in regional temperatures will cause reversible or irreversible changes in the depth or strength of the permafrost layer. Therefore, the above factors need to be fully considered during structural design. In the present invention, it mainly refers to the depth of the steel sheet pile retaining wall inserted into the permafrost layer. When the permafrost layer is disturbed due to force majeure, the above depth can ensure the water retaining performance and stability of the steel sheet pile retaining wall.

[0058] Specifically, the steel sheet pile retaining wall is formed by splicing one or more of U-shaped, Z-shaped, O-shaped, and I-shaped cold-bent steel sheet piles or hot-rolled Larsen steel sheet piles; a locking structure is provided at the joints of the steel sheet piles. The steel sheet piles of the above structure have been proven to have good strength and stability in a variety of application scenarios, so the present invention uses the above-mentioned type of steel sheet piles; the locking arrangement at the joints is to ensure that the steel sheet pile retaining wall has good integrity and avoids loosening. Particularly preferably, the structural design of the locking preferably has a structure with multiple "return bends", such as a paper clip-shaped design (such as Figure 1 As shown), on the one hand, the stability of the lock mouth can be improved, and on the other hand, the waterproof performance is also improved, so that even if a small amount of external water penetrates, it is difficult to enter the road foundation through the lock mouth.

[0059] Specifically, the thickness of the steel sheet pile is 3 to 16 mm, the width is 300 to 900 mm, and the length is 4 to 16 meters. The thickness and width of the steel sheet pile are mainly to ensure that it has sufficient structural strength. Therefore, the steel sheet pile should not be too thick or too thin. Too thin will lead to insufficient strength, and too thick will lead to excessive cost. Too narrow width of the steel sheet pile will lead to too many joints, which will affect the overall strength on the one hand and increase the construction difficulty on the other hand. The steel sheet pile should not be too wide, otherwise it will lead to insufficient strength and problems such as distortion and breakage during the piling process. The length of the steel sheet pile is mainly determined according to the depth of the permafrost layer in the actual environment. The 4 to 16 meter long steel sheet pile can meet the construction requirements in most environments and can be driven into the permafrost layer 2 to 5 meters below.

[0060] Furthermore, in addition to meeting the corrosion resistance requirements, steel sheet piles in frozen soil areas must also have a certain low-temperature toughness to prevent breakage due to stress impact caused by temperature changes and soil freezing and thawing during construction or use, which would affect the protective effect.

[0061] Preferably, a waterproof filler is provided in the internal gap of the lock structure at the joint of the steel sheet piles of the steel sheet pile retaining wall; and a waterproof cloth is provided on one side of the steel sheet pile retaining wall along the water-facing direction of the runoff. The provision of the waterproof filler and the waterproof cloth can further improve the waterproof performance of the steel sheet pile retaining wall.

[0062] The present invention also discloses a construction method applicable to the foundation structure, which specifically comprises the following steps:

[0063] S1 Exploration and Design: Measure the soil moisture content on both sides of the road, explore the surface and underground runoff directions, determine the protection area of ​​the steel sheet pile retaining wall, and design the waterproof system structure according to the runoff characteristics in the protection area;

[0064] S2 Road surface cleaning: remove the topsoil, grass, all garbage, shrubs, trees, stones, waste and other debris within the roadbed;

[0065] S3 Steel Sheet Pile Driving: Prepare steel sheet piles of appropriate specifications, drive them into the predetermined positions according to the pre-designed design and splice them into steel sheet pile retaining walls;

[0066] S4 Anti-seepage treatment and compaction: After the steel sheet pile retaining wall is sealed and anti-corrosion treated, the foundation is compacted to obtain a compacted layer;

[0067] S5 roadbed backfill and pavement compaction: The roadbed is backfilled and the pavement is compacted on the compacted layer to obtain a frozen soil highway foundation structure with water retaining function.

[0068] The construction method provided by the present invention is relatively simple and can be implemented relying on existing construction technology and equipment. Currently, small-scale field tests have been carried out in some permafrost areas of the Qinghai-Tibet Plateau. The construction method is feasible and has achieved good results (see Example 1), and is suitable for road construction and highway foundation waterproofing in large permafrost areas.

[0069] Furthermore, the waterproof system structure design in step S1 includes:

[0070] (1) When both surface runoff and underground runoff exist in the protection area, drainage channels are set up on the water-facing surface, water culverts are set up at appropriate locations on the highway, and a comprehensive foundation water retaining protection system is implemented in combination with steel sheet pile retaining walls;

[0071] (2) When only underground runoff exists in the protection area, a steel sheet pile retaining wall is set up in the runoff area and a suitable channel is set up for the underground runoff by means of bridging, bridge connection or underground culvert at a suitable location.

[0072] Structural designs such as water culverts, spans, bridges or underground culverts can better and faster drain external water whose flow direction has been changed by the highway itself and the steel sheet pile retaining wall. On the one hand, it can better protect the highway subgrade, and on the other hand, it can also help reduce the impact of highway construction on the ecological environment, so as to avoid the blockage of water in some areas due to highway obstruction, which in turn leads to negative environmental impacts such as vegetation withering and animal population shrinkage.

[0073] Specifically, the specific operation of the sealing treatment in step S4 is to use waterproof filler to fill and seal the gaps at the joints of the steel sheet piles. The filling and sealing treatment can refer to the filling process in the prior art, and be appropriately adjusted and optimized in combination with specific construction conditions and steel sheet piles / steel sheet pile retaining wall structures, for example:

[0074] 1) Use sediment filling. Filling the gaps at the locking points of the steel sheet piles with sediment is a common method to solve the sealing problem between the steel sheet piles. Natural infiltration and plugging are also common methods, which can effectively prevent the penetration of groundwater and other fluids and play a sealing role;

[0075] 2) Use sealing strips. If the on-site construction method allows one side of the steel sheet pile wall to be exposed, the lock can be sealed by using sealing strips;

[0076] 3) Use asphalt sealing. When piling, brush asphalt on the lock of the steel sheet pile, and the lock will bite to achieve a sealing effect. The above sealing methods can also be used in combination.

[0077] Specifically, the specific operation of the anti-corrosion treatment in step S4 is:

[0078] When the steel sheet pile is made of ferritic stainless steel and the frozen soil contains chloride ions, a sacrificial anode anti-corrosion measure is adopted;

[0079] Since ferritic stainless steel has relatively poor resistance to chloride ion corrosion, the effect of coating and plating protective layer is not good, and sacrificial anode anti-corrosion measures are preferred;

[0080] When the steel sheet pile is made of low alloy low temperature corrosion resistant steel or high quality carbon structural steel, surface coating technology or sacrificial anode anti-corrosion measures are adopted;

[0081] For external water with low ion concentration and no SO4 2- and Cl - When using high-quality carbon structural steel or low-temperature corrosion-resistant steel sheet piles with a coated protective layer, corrosion can be effectively prevented; when the ion concentration in the water is high or there is a large amount of SO4 2- and Cl - When using steel sheet piles, cathodic protection technology (i.e. sacrificial anode) must be used to improve their corrosion resistance.

[0082] On the one hand, sealing and anti-corrosion treatment effectively improve the waterproof and anti-corrosion performance of the steel sheet pile retaining wall, and on the other hand, significantly increase the service life of the steel sheet pile retaining wall. It is worth noting that the service life of the steel sheet pile retaining wall should not be increased indefinitely, that is, the anti-corrosion treatment does not seek to pursue excessively high anti-corrosion performance, but to make the service life of the steel sheet pile retaining wall as close to the service life of the road as possible. Therefore, in actual implementation, the appropriate anti-corrosion process should be selected according to the renovation time limit of the road design to carry out anti-corrosion treatment on the steel sheet pile / steel sheet pile retaining wall.

[0083] More specifically, the service life of the steel sheet pile retaining wall should be made as slightly longer than the service life of the road as possible; on the one hand, it avoids excessive costs caused by performance overflow (mainly referring to anti-corrosion performance), so that when the road is renovated, the steel sheet pile retaining wall also reaches its retirement time and can be replaced simultaneously with the road renovation; on the other hand, it reduces maintenance and replacement of the steel sheet pile retaining wall during its service life, and reduces maintenance costs as much as possible, even close to 0, while meeting the protection performance requirements.

[0084] Examples and Comparative Examples

[0085] Example 1: This example uses a hat-shaped steel sheet pile (such as Figure 1 As shown), the steel sheet pile is made of low-alloy low-temperature corrosion-resistant steel, with a thickness of 8 mm, a width of 600 mm, and a length of 6 meters. It is connected by locking piling to form a steel sheet pile retaining wall. The steel sheet pile retaining wall is located 0.2m inside the edge of the roadbed cross section, inserted into the permafrost layer about 2 to 3m (the distance between the permafrost layer and the surface is not uniform), and sealed and anti-corrosion treated (using a coating protection process). The corresponding protection area of ​​this embodiment is about 100m long, with both surface and underground runoff water, and relatively little surface water. The steel sheet pile retaining wall is set on one side, and no drainage channel is set.

[0086] Example 2: Compared with Example 1, a drainage channel is provided at 0.1 m inside the edge of the roadbed cross section, and other parameters and processes are the same as those of Example 1.

[0087] Comparative Example 1: No steel sheet pile retaining wall is set, and the main structure of the foundation and other parameters and processes are the same as those in Example 1.

[0088] Comparative Example 2: No steel sheet pile retaining wall was set, and the main structure of the foundation and other parameters and processes were the same as those in Example 2 (a drainage channel was set).

[0089] The change of foundation humidity was measured with a hygrometer. The humidity change of the foundation with steel sheet pile wall water retaining (Examples 1 and 2) was significantly smaller than that of the ordinary foundation, and the foundation humidity was significantly reduced; in the case of a drainage ditch (Example 2), the foundation humidity was even lower. The specific results are shown in Table 1.

[0090] Table 1: Humidity variation data of frozen soil highway foundation of the embodiment and the comparative example

[0091] Time / Day 1 2 3 4 5 6 7 8 9 Example 1 Highway foundation humidity / % 13.1 13.1 13.1 13.1 13.1 13.3 13.4 13.4 13.5 Example 2 Highway foundation humidity / % 11.2 11.2 11.2 11.3 11.2 11.4 11.5 11.4 11.6 Comparative Example 1 Highway foundation humidity / % 25.5 27.3 29.1 29.0 31.2 33.2 37.2 37.6 39.3 Comparative Example 2 Highway foundation humidity / % 18.3 18.8 19.0 19.4 19.4 19.9 20.2 21.1 22.3

[0092] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A frozen soil highway foundation structure, characterized in that: The structure comprises a steel sheet pile retaining wall (5) and a main foundation structure; the main foundation structure comprises, from top to bottom, a road surface (8), a roadbed (6), a compacted layer (7), and a permafrost layer (10); The steel sheet pile retaining wall (5) is vertically arranged on the inner side of the edge of the cross section of the roadbed (6) along the upstream direction of the runoff, and the bottom is inserted into the permafrost layer (10). The edge of the compacted layer (7) is connected to the backwater side of the steel sheet pile retaining wall (5), and the upper surface of the compacted layer (7) is flush with the ground surface (9).

2. The foundation structure according to claim 1, characterized in that: The top of the steel sheet pile retaining wall (5) is flush with the ground surface (9) or slightly higher than the ground surface (9) and lower than the height of the corresponding position of the roadbed (6); both sides of the roadbed (6) are slope structures.

3. The foundation structure according to claim 1, characterized in that: A drainage channel (4) is also provided on the outer side of the edge of the cross section of the roadbed (6) along the extension direction of the highway.

4. The foundation structure according to claim 1, characterized in that: The bottom of the steel sheet pile retaining wall (5) is inserted into the permafrost layer (10) by 2 to 5 m.

5. The foundation structure according to claim 1, characterized in that: The steel sheet pile retaining wall (5) is formed by splicing one or more of U-shaped, Z-shaped, O-shaped, and I-shaped cold-bent steel sheet piles or hot-rolled Larsen steel sheet piles; a locking structure is provided at the splicing position of the steel sheet piles (1); the steel sheet piles (1) have a thickness of 3 to 16 mm, a width of 300 to 900 mm, and a length of 4 to 16 m.

6. The foundation structure according to claim 5, characterized in that: A waterproof filler (2) is provided in the internal gap of the lock structure at the joint of the steel sheet piles (1) of the steel sheet pile retaining wall (5); and a waterproof cloth (3) is provided on one side of the steel sheet pile (1) retaining wall along the water-facing direction of the runoff.

7. A construction method applicable to the foundation structure according to any one of claims 1 to 6, characterized in that: The specific steps include: S1 Exploration and design: Measure the soil moisture content on both sides of the road, explore the surface (9) and underground runoff direction, determine the protection area of ​​the steel sheet pile retaining wall (5), and design the waterproof system structure according to the runoff characteristics in the protection area; S2 Road surface cleaning: remove the topsoil, grass, all garbage, shrubs, trees, stones, waste and other debris within the roadbed (6); S3 steel sheet pile driving: preparing steel sheet piles (1) of suitable specifications, driving the steel sheet piles (1) into predetermined positions according to a pre-designed design, and splicing them into a steel sheet pile retaining wall (5); S4: Anti-seepage treatment and compaction: After the steel sheet pile retaining wall (5) is sealed and treated with anti-corrosion, the foundation is compacted to obtain a compacted layer (7); S5 roadbed backfilling and road surface compaction: backfilling the roadbed (6) and compacting the road surface (8) on the compacted layer (7) to obtain a frozen soil highway foundation structure with a water retaining function.

8. The construction method according to claim 7, characterized in that: The waterproof system structure design in step S1 includes: (1) When both surface runoff and underground runoff exist in the protection area, a drainage channel (4) is set up on the water-facing surface, a water culvert is set up at a suitable location on the highway, and a steel sheet pile retaining wall (5) is combined to comprehensively implement a foundation water retaining protection system; (2) When only underground runoff exists in the protection area, a steel sheet pile retaining wall (5) is set in the runoff area and a suitable channel is set for the underground runoff by means of bridging, bridge connection or underground culvert at a suitable location.

9. The construction method according to claim 7, characterized in that: The sealing treatment in step S4 includes filling and sealing the gaps at the joints of the steel sheet piles (1) with a waterproof filler (2).

10. The construction method according to claim 7, characterized in that: The anti-corrosion treatment in step S4 includes: When the steel sheet pile (1) is made of ferritic stainless steel and the frozen soil contains chloride ions, a sacrificial anode anti-corrosion measure is adopted; When the steel sheet pile (1) is made of low-alloy low-temperature corrosion-resistant steel or high-quality carbon structural steel, surface coating technology or sacrificial anode anti-corrosion measures are adopted.

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