CN109403360B

CN109403360B - Roadbed slope freeze-thaw collapse prevention and control method based on dot matrix type assisted integration drainage

Info

Publication number: CN109403360B
Application number: CN201811526850.XA
Authority: CN
Inventors: 高伟; 许珊珊; 曾明鸣; 高铭; 任少辉; 白义松; 孙巍; 左贵林; 毛景滨
Original assignee: Heilongjiang Academy Of Highway Sciences
Current assignee: Heilongjiang Academy Of Highway Sciences
Priority date: 2018-12-13
Filing date: 2018-12-13
Publication date: 2020-08-07
Anticipated expiration: 2038-12-13
Also published as: CN109403360A

Abstract

A roadbed slope freeze-thaw collapse prevention and control method based on dot matrix type assisted integration drainage belongs to the technical field of roadbed slope freeze-thaw collapse prevention and control method research. The method can solve the defects of large earthwork engineering amount, long construction period, difficult adjustment and the like, can accelerate removal of accumulated moisture of the soil body and actively inhibit freeze-thaw collapse of the shallow layer of the roadbed slope, and particularly, promotes the accelerated melting of frozen soil around a 'water collecting and draining pipe' in the spring melting period by utilizing the cold and hot air convection principle to fulfill the aims of actively and timely draining off the moisture accumulated by melting of the frozen soil in advance and preventing the rapid reduction of the shear strength of the shallow layer soil body of the roadbed slope from causing the freeze-thaw collapse of the shallow layer. The invention also has the advantages of economy, applicability, flexible arrangement and simple and convenient construction; the set shape, range and time can be timely adjusted according to the dynamic change of the field situation; the method is not only suitable for preventing and treating freeze-thaw collapse of the shallow layer of the newly-built highway subgrade side slope, but also suitable for timely treating freeze-thaw collapse of the shallow layer of the highway subgrade side slope in the operation period.

Description

Roadbed slope freeze-thaw collapse prevention and control method based on dot matrix type assisted integration drainage

Technical Field

The invention belongs to the technical field of research on roadbed slope freeze-thaw collapse prevention and treatment methods, and particularly relates to a roadbed slope freeze-thaw collapse prevention and treatment method based on dot matrix type assisted melting and water drainage, which is mainly used for preventing and treating roadbed slope freeze-thaw collapse of highways in seasonal frozen soil areas.

Background

The distribution range of the roadbed slopes along the road is wide, the influence on the natural environment is large, and the stability of the slopes directly or indirectly influences the use function and the service life of the highway. In the development process of road engineering construction technology in China, the stabilization and protection technology of the road subgrade slope surface is continuously improved, but due to the difference of soil quality and geographical climate conditions in different areas and the cross application of masonry protection, geotechnical materials, plant protection and landscaping, the diversity of protection types and protection schemes is caused.

Due to relative shortage in basic application research and difference in use, and due to different geography, climate and engineering construction scale in different regions, the use effect of the similar comprehensive protection scheme is different. Particularly, under the climatic conditions of a special high-latitude low-altitude deep-season freezing region in Heilongjiang province, because of the action of freeze-thaw cycles, hidden dangers such as frost heaving and shallow layer collapse exist on the roadbed side slope, particularly on the soil cutting side slope, if the adopted protection technical measures are not targeted enough, annual collapse can occur, and roadbed side slope collapse at different degrees can occur in continuous years after some roads are communicated. The related diseases not only affect the overall use function of the road, but also greatly increase the difficulty and cost of later maintenance management and repair, and have adverse effects on the driving and road environment.

The freeze-thaw damage of the road subgrade side slope is one of the peculiar subgrade side slope diseases in a cold area, the diseases exist in different degrees on a filled embankment side slope and an excavated cutting side slope, the disease mechanisms of the embankment side slope and the excavated cutting side slope are similar, but the excavated road section is common, the freeze-thaw damage mainly shows that ① masonry protection structure frost heaving or thaw settlement leads to loose and slide of the protection structure when serious, ② side slope shallow layer freeze-thaw collapse instability is caused, the former is mainly caused by slope water seepage or interlayer water frost heaving and thawing, the latter is related to the shallow layer stability of the side slope in a frozen area, the two are related to water and freeze thawing in side slope soil, and the influence factors of the shallow layer freeze-thaw collapse instability are relatively complex.

The factors influencing the freezing and thawing collapse of the roadbed slope mainly comprise downward sliding force generated by the self weight of slope soil, interlayer water or slope surface downward seepage water, increase soil body gravity and reduce the shear strength of soil, moisture accumulation and sliding bed action (the actual sliding surface is generally slightly higher than the freezing and thawing interface) at the freezing and thawing junction formed by freezing and thawing, additional load formed by slope surface masonry protection and the like. The main reasons for slumping are: due to the existence of rain and snow in late autumn and early winter and the influence of freezing and thawing caused by the repeated change of air temperature before freezing, the moisture on the upper soil layer of the roadbed side slope is accumulated to a certain degree, the slope surface of the side slope is covered by ice and snow in winter, the ice and snow are gradually melted and infiltrated into the slope soil in the spring thawing period, the soil layer on the upper part of the side slope starts to be melted at the moment, but the soil layer on the lower part is still in a frozen state, the moisture in the soil layer on the upper part cannot continuously infiltrate, so that the soil on the upper part of the side slope is saturated or even supersaturated, the shear strength of the soil body is greatly reduced, a possible slide bed is formed by a freezing and thawing interface, the repeated day and night air temperature and the creeping under the.

At the present stage, the protection emphasis on the roadbed side slope is still focused on ensuring the overall stability and slope stability of the side slope, and the prevention measures for the freeze-thaw collapse of the side slope are relatively few. At present, the most important method is to arrange shallow drainage facilities, namely, a branch-shaped water collecting and drainage network is arranged in a certain depth range of a slope surface so as to timely drain melted and accumulated water or water between slope layers to the outside of a roadbed slope; secondly, a reinforced concrete frame and the like are adopted to form a stable structural mechanical support on the slope surface of the roadbed side slope; in addition, for the roadbed slope protection structure adopting the concrete precast hollow blocks, when frost heaving and slumping signs exist, wood piles are vertically driven into the slope surface to a depth of 50-100 cm in a dispersed and staggered mode, so that the precast block structure is stabilized.

The shallow drainage facility needs detailed investigation and design, the workload of trench excavation is increased, the determination of drainage depth and drainage range is a difficult point, and the difficulty of adjustment after construction is high; the method for reinforcing the roadbed slope concrete hollow precast block by the wooden pile belongs to temporary emergency treatment measures and is not ideal in effect.

The current prevention and control measures for freezing-thawing slumping of the shallow layer of the roadbed side slope mainly passively remove water in a slope body which is gradually accumulated by natural thawing. Or by using structural support to provide an active mechanical protection. The former is not active enough, and only can wait for the frozen soil layer to melt passively, and the melted water is collected and discharged passively, so that the former has certain delay, and has defects in the aspect of actively inhibiting the rising of the water content of the slope soil body; the masonry support structure of the latter is high in cost and not economical enough, and meanwhile, the slope soil body in the frame still has the possibility of local collapse. Both the two methods need to dig grooves, so that the earthwork amount is increased, the construction procedures are increased, and the construction period is correspondingly prolonged; simultaneously both belong to disposable setting shaping, if later stage needs the adjustment, its construction degree of difficulty is very big.

Disclosure of Invention

The invention aims to solve the defects of high construction cost, insufficient economy, large earthwork amount, long construction period, difficult adjustment and the like of passively collecting and removing the melted water by the conventional roadbed slope shallow freezing and thawing slump prevention measures, and provides a roadbed slope freezing and thawing slump prevention method based on dot-matrix assisted melting and drainage. The invention also has the advantages of economy, applicability, flexible arrangement and simple and convenient construction; the set shape, range and time can be timely adjusted according to the dynamic change of the field situation; the method is not only suitable for preventing and treating freeze-thaw collapse of the shallow layer of the newly-built highway subgrade side slope, but also suitable for timely treating freeze-thaw collapse of the shallow layer of the highway subgrade side slope in the operation period. In the method, the collection points for collecting and draining water are uniformly distributed, the melted water is drained in time, the setting mode and the setting time are more flexible, the shear strength of the shallow soil body on the upper part of the highway subgrade side slope can be maintained, and the stability of the shallow layer of the subgrade side slope can be improved.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a roadbed slope freeze-thaw collapse prevention and control method based on dot matrix type assisted integration drainage comprises the following specific steps:

the method comprises the following steps: manufacturing and preparing the melting-assisting water collecting and draining pipe

⑴ the water collecting and draining pipe is formed by nesting an outer pipe and an inner pipe;

⑵ the outer tube wall is slotted, the inner tube is round;

⑶ when the holes are opened, the holes of the inner pipe and the outer pipe are aligned;

⑷ wrapping the outer wall of the inner pipe with double-layer reverse-filtering nonwoven geotextile;

⑸ embedding the inner pipe into the outer pipe, aligning the positioning holes by rotating the inner pipe left and right, then inserting an iron wire to penetrate through the water collecting and discharging pipe, and bending two ends of the iron wire to avoid slipping;

⑹ the round hole at the tip of the water collecting and discharging pipe is sealed by a wooden plug, so as to prevent soil from entering the pipe when the water collecting and discharging pipe is driven into the soil;

step two: judging whether freeze-thaw collapse is possible on roadbed slope

Judging whether the roadbed slope has the possibility of shallow layer freeze-thaw collapse and the depth of the shallow layer freeze-thaw collapse by adopting a mechanical method or an empirical method; the mechanical method utilizes a freeze-thaw slump stability checking formula, a freeze-thaw slump stability safety coefficient is checked and calculated according to physical mechanical parameters of a side slope soil body and analyzed, when the safety coefficient is less than 1.25, the possibility of slumping exists, and the slumping depth is judged according to the position of a sliding surface; the empirical method is comprehensively judged according to the conditions of whether interlayer water is exposed on the slope surface of the roadbed side slope, whether the adjacent side slope slips or not, whether snow cover is formed in winter or not and whether water seepage is formed at the top of the slope or not; judging that shallow freeze-thaw slump is possible on a fine soil slope with interlayer water exposure, a fine soil slope with moist soil on the shady side and accumulated snow in winter and a slope with local slump, and taking the depth of the generated slump as a reference standard; when the non-collapse depth can be referred to, setting according to 70 cm;

step three: determining the setting position and the lattice range of the water collecting and draining pipe

⑴, for the roadbed slope with interlayer water exposure, the setting position takes the interlayer water exposure range as the reference, the setting range is 3-5 m respectively extending at the left and right of the exposure range, 1-3 m extending at the upper part and 3-5 m extending at the lower part;

⑵, for roadbed slopes with no obvious interlayer water signs and no obvious downward water seepage at the top of the slopes, but possible shallow layer freeze-thaw collapse, the setting range is based on the range of 1/3 of the slope height in the middle of the roadbed slope;

⑶ for roadbed side slopes which have no obvious interlayer water sign but have downward water seepage at the top of the slopes, the arrangement range of the roadbed side slopes is based on the range of the height of the upper part of the roadbed side slopes from the tops of the slopes 1/3-1/2 while the interception and seepage prevention of water flow at the tops of the roadbed are enhanced;

⑷ for roadbed slopes which have undergone freeze-thaw collapse, under the conditions of re-repairing and well-done slope scouring protection, the setting range of the roadbed slopes takes the original collapse range as a reference, and the coverage range is extended with reference to item (1) in the step;

step four: determining the setting depth of the water collecting and draining pipe

The water collecting and draining pipe is driven into the slope soil at an outward inclination of 3-5% of the horizontal plane, the length of the water collecting and draining pipe is L, the maximum depth of one end of the water collecting and draining pipe driven into the soil from the slope surface is h, and the value of h is the set depth;

the setting depth h of the water collecting and discharging pipe is as follows:

for ⑴ in the third step, the water exposure range between layers is 60-70 cm within the range of extending 3m from left to right and 1m above and 1-2 m below the water exposure range, and the other parts are 40-50 cm, namely the depth of the part with much water accumulation is correspondingly increased;

⑵ in the third step, the setting depth can be gradually transited in the upper part of the setting range of 40-50 cm and the lower part of the setting range of 60-70 cm, or the setting range can be divided into an upper part and a lower part, and the setting depth is consistent in the horizontal direction by adopting a scheme of shallow upper part and deep lower part;

⑶ in the third step, the arrangement mode of the upper part is deep and the lower part is shallow, and the arrangement depth in the horizontal direction is consistent;

for ⑷ in the third step, the original collapse range is 60-70 cm with the left and right extended by 3m and the upper and lower parts thereof by 1-2 m, and the other parts are 40-50 cm;

step five: determining the arrangement distance of the water collecting and discharging pipes

The arrangement distance of the water collecting and discharging pipes is 2-3 m, and two adjacent rows of water collecting and discharging pipes are arranged in a vertically staggered manner; setting a lower limit for the distance when the water content of the side slope soil body is large, and taking an upper limit when the water content is small; the corresponding step four: setting a lower limit of the distance when the setting depth is 60-70 cm; setting the upper limit of the distance when the setting depth is 40-50 cm;

step six: driven into a water collecting and draining pipe

The hole at the soil inlet end of the water collecting and discharging pipe is wedged by a wooden plug and is wrapped by an iron sheet; the exposed end of the drain pipe is padded by a wood block or a thick-wall metal sleeve and then is hit; for hard soil, a hole is formed by a puncher initially, the hole forming aperture is based on the outer diameter of the water collecting and discharging pipe, then the water collecting and discharging pipe is driven into the hole, the hole is formed and driven into the hole according to the requirement of inclining outwards by 3-5% during initial hole forming and driving into the water collecting and discharging pipe, and the length of the exposed pipe end of the slope surface is not less than 10 cm;

step seven: finishing

Whether sundries exist in the water collecting and draining pipe after the installation is checked, the water collecting and draining pipe is cleaned in time, then the exposed end is temporarily wrapped by geotextile, soil sundries are prevented from entering the follow-up slope surface during maintenance, and the geotextile can be naturally weathered after months.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention provides a roadbed slope shallow layer freeze-thaw collapse prevention and control method based on dispersed dot-matrix type water collection and drainage for the first time.

2. The invention firstly provides a melting-assisted water collecting and draining pipe concept and a structure thereof, which are applied to a freezing-thawing slumping prevention and control method for a roadbed slope shallow layer of a dot-matrix melting-assisted water collecting and draining.

3. The interlayer reverse filtering structure of the specially designed water collecting and draining pipe ensures the reliability and durability of the water collecting and draining effect; the hollow pipeline structure is hollow, inclined and communicated with the slope surface, so that the cold and hot air convection principle can be effectively utilized in the spring thawing period, the cold and the humidity in the frozen soil layer are conducted to the outside of the roadbed slope surface, and meanwhile, relatively warm air near the slope surface is brought into the soil body of the side slope, thereby being beneficial to timely thawing and removing moisture accumulated in the soil body; the water collecting and draining pipe driven into the side slope can also exert the effect of the anti-slide pile, and can effectively maintain the shear strength necessary for stabilizing the shallow layer of the side slope soil body. The main effect of the reverse filtering structure is to isolate water and soil, and meanwhile, the water permeability can be kept for a long time, so that water can enter the water collecting and discharging pipe from the side hole of the pipe, and then is discharged to the outside of the slope surface through the water collecting and discharging pipe, and the reverse filtering structure also has the effect of water collecting and discharging.

4. The setting range, the setting depth (40-70 cm), the inclination of slope (3-5%), the setting interval (2-3 m) and the corresponding setting method of the dot matrix type water collecting and draining pipe are provided.

5. By adopting a dot-matrix arrangement mode, the roadbed slope freeze-thaw collapse prevention and control method based on dot-matrix assisted melting, water collection and drainage has the advantages of flexible arrangement mode, and dynamically and timely adjustment of arrangement time and arrangement scheme. The method is suitable for protection and treatment of freeze-thaw collapse of the roadbed slope in different stages of new construction, existing construction, reconstruction and the like.

6. The invention can effectively reduce the earthwork amount for preventing and controlling the freezing and thawing slumping of the roadbed side slope and effectively avoid the disturbance to the slope soil body structure.

7. The comprehensive construction cost of the invention is within 50% of the branch-shaped shallow water collecting and draining facility and less than 10% of the reinforced concrete structure supporting frame, and can effectively reduce or avoid the shallow freezing-thawing slumping damage of the roadbed side slope, obviously reduce the maintenance and repair cost brought by the shallow freezing-thawing slumping damage, keep the integral use function and environment coordination of the road, and have obvious social benefit and economic benefit.

8. The roadbed slope freeze-thawing slumping prevention and control method based on the dot-matrix assisted water collection and drainage can avoid disturbance of the excavated water collection and drainage channels on the slope surface, the collection points of the water collection and drainage channels are uniformly distributed, and the arrangement range adjustment and the construction time mastering are very flexible. The method is suitable for preventing and treating the freezing-thawing slump of the shallow layer of the roadbed slope of the newly-built highway and is also suitable for treating the freezing-thawing slump of the shallow layer of the roadbed slope in the operation period.

Drawings

FIG. 1 is a schematic diagram of roadbed slope freeze-thaw collapse;

FIG. 2 is a graph of set depth h versus tube length L;

FIG. 3 is a schematic size diagram of an outer tube structure;

FIG. 4 is a schematic size diagram of an inner tubular structure;

FIG. 5 is a schematic diagram of an inner tube and an outer tube nested together;

fig. 6 is a schematic view of the arrangement of the water collecting and discharging pipe.

Detailed Description

The technical solutions of the present invention are further described below with reference to the drawings and the embodiments, but the present invention is not limited thereto, and modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

The dot matrix is as follows: the appearance is in a point-shaped distribution arrangement mode. A roadbed: the strip-shaped structure serving as a road foundation is referred to as a road bed. Roadbed side slope: in order to ensure the stability of the roadbed, the two sides of the roadbed are provided with slopes with certain slopes. Cutting side slope: and side slopes on two sides of the excavated roadbed lower than the original ground. Embankment side slope: fill the side slopes formed on both sides of the roadbed (embankment). And (3) side slope instability: the side slope is damaged structurally, such as slumping, dumping, collapsing, crumbling and the like. Freezing and thawing landslide of the roadbed side slope: in the spring melting period, ice and snow are gradually melted and infiltrated into soil on the slope surface of the roadbed, so that the water content of soil on the upper part of the slope surface tends to be saturated, the shear strength of the soil is greatly reduced, the freezing and thawing interface becomes a possible slide bed, and the melted soil layer creeps and slides downwards along the frozen layer surface, so that the slope shallow layer slides, collapses and is unstable. And (3) collapse of shallow layer of roadbed side slope: and (4) the landslide within 2m of the depth of the slope of the roadbed side slope is generally between 20 and 70 cm. Interlayer water of roadbed side slope: the underground water in the water-containing soil layer of the roadbed side slope is generally positioned between two soil layers which are not easy to permeate water, a wet layer which is obviously different from the upper soil layer and the lower soil layer can be presented after the side slope is excavated, and the water source can flow when sufficient.

According to field investigation, the main manifestation form of freeze-thaw collapse of the roadbed side slope is shallow layer collapse within a depth range of 10-120 cm from the surface of the side slope, and the majority of the freeze-thaw collapse is 20-70 cm. The main reason is frost heaving and thawing of the slope soil layer. For the slope surface protected by masonry grids or concrete precast blocks, frost heaving and thawing of the soil layer can possibly cause uplifting and crumbling of a masonry protection structure, and under the action of additional load of masonry of the slope surface, shallow layer freeze-thaw collapse is easy to occur when the temperature rises again in spring and the soil layer is thawed; plant protection or geotechnical materials are matched with plant protection for equilateral slope surfaces, and shallow layer freeze-thaw collapse is mainly caused by frost heaving and thawing of shallower soil layers of the slope surfaces. Theoretical analysis and field tracking observation show that the freeze-thaw collapse of the highway subgrade side slope has particularity, the slope is not the only determining factor, the slope stability can not be ensured by adopting a method for greatly reducing the slope for the freeze-thaw collapse possibility, particularly the cutting side slope with interlayer water exposure, and the method is mainly used for timely removing water accumulated in the side slope soil body.

The dimensions of the outer tube in the present invention are as follows: the angle of the tip is 35-45 degrees; the length of the long hole is 30mm, and the width of the long hole is 7 mm; the distance between the long holes along the curved surface direction is 20 mm; the inner diameter of the outer pipe is 50mm, and the outer diameter is 60 mm; the distance between the outer end of the outer pipe and the positioning hole is 30-50 mm; the distance between the outer end of the outer pipe and the nearest long hole is 100 mm; the distance between the long holes along the axial direction is 15 mm; the distance between the tip and the nearest long hole is more than or equal to 50 mm; the dimensions of the inner tube in the present invention are as follows: the distance between the outer end of the inner pipe and the positioning hole is 30-50 mm; the distance between the tip and the nearest round hole is more than or equal to 50 mm; the angle of the tip is 35-45 degrees; the distance between the outer end of the inner pipe and the nearest round hole is 100 mm; the diameter of the round hole is 10 mm; the number of the round holes is 2, the clear distance between the round holes in the same axial group is 10mm, and the clear distance between the groups is 15 mm; the distance between the round holes along the direction of the curved surface is 8 mm; the inner diameter of the inner pipe is 30-35 mm, and the outer diameter is 40 mm; the dimensions given above are the usual design dimensions, and besides, the dimensions of the inner and outer tubes can be adjusted by those skilled in the art according to the materials selected by the present invention, as long as the structural form and design method of the present invention are satisfied.

The first embodiment is as follows: the embodiment describes a roadbed slope freeze-thaw collapse prevention and control method based on dot matrix type assisted melting and water drainage, which comprises the following specific steps:

⑴ the water collecting and draining pipe is formed by nesting an outer pipe 2 (figure 3) and an inner pipe 1 (figure 4) (figure 5);

⑵ the opening of the outer tube 2 is a long hole and the opening of the inner tube 1 is a round hole (see fig. 3 and 4); the specification and size, the materials and the shape of the water collecting and discharging tube are not limited to those shown in the figure)

⑶ when the holes are opened, the holes of the inner tube 1 and the outer tube 2 should be aligned;

⑷ wrapping the outer wall of the inner tube 1 with a double-layer reverse-filtering type non-woven geotextile 5 (meeting the requirement of the non-woven geotextile with the reverse filtering function in section 4.1 of technical specification GB/T50290-2014 for geosynthetic material application);

⑸ the inner tube 1 is inserted into the outer tube 2, the positioning hole 3 is aligned by rotating the inner tube 1 left and right, and then the inner tube 12 is inserted^#Or 14^#The iron wire 6 penetrates through the water collecting and discharging pipe, and two ends of the iron wire 6 need to be bent to avoid slipping;

⑹ the round hole at the tip of the water collecting and draining pipe is sealed by the wooden plug 4 to avoid soil entering the pipe when the water collecting and draining pipe is driven into soil, the wooden plug 4 is used to prevent soil entering the pipe from blocking when the water collecting and draining pipe is driven into a side slope (the wooden plug 4 can also play a role of preventing blocking during use), so the pipe mouth of the driving end needs to be sealed by the wooden plug 4 and does not need to be removed.

Step two: judging whether freeze-thaw collapse is possible on roadbed slope

Judging whether the roadbed slope has the possibility of shallow layer freeze-thaw collapse and the depth of the shallow layer freeze-thaw collapse by adopting a mechanical method or an empirical method; the mechanical method comprises the steps of checking a freeze-thaw collapse stability safety coefficient and analyzing by using a freeze-thaw collapse stability checking formula according to physical mechanical parameters of a slope soil body (calculated by a formula in seasonal frozen soil area road design and construction technical specifications or highway subgrade slope protection technical guidelines in Heilongjiang province, wherein corresponding parameters are determined according to the formula), judging the freeze-thaw collapse stability safety coefficient when the safety coefficient is less than 1.25, judging the collapse depth according to the sliding surface position (specifically judging according to the guidelines or the formula in the specifications, wherein the safety coefficient is 1.25); the stability checking formula and the analysis method can refer to the technical guidance for protecting the roadbed slope of the highway in Heilongjiang province and the technical specification for designing and constructing the highway in seasonal frozen soil region; the empirical method is comprehensively judged according to the conditions of whether interlayer water is exposed on the slope surface of the roadbed side slope, whether the adjacent side slope slips or not, whether snow cover is formed in winter or not and whether water seepage is formed at the top of the slope or not; judging that shallow freeze-thaw slump is possible on a fine-grained soil slope with interlayer water exposure, a fine-grained soil slope with moist soil on the back and accumulated snow in winter and a slope with local slump, and taking the depth of the generated slump as a reference standard; when the non-collapse depth can be referred to, setting according to 70 cm;

⑵, for roadbed slopes with no obvious interlayer water sign, no obvious downward water seepage at the top of the slopes and possible shallow layer freeze-thaw collapse, the setting range is determined by the range of 1/3 of the slope height in the middle of the roadbed slope, and the corresponding length is determined by field observation;

⑶ for roadbed side slopes which have no obvious interlayer water sign but have downward water seepage on the top of the slopes, the setting range of the roadbed side slopes is determined by the range of the upper parts of the roadbed side slopes from the tops of the slopes 1/3-1/2 to the slope heights while the interception and seepage prevention of water flow on the top of the roadbed are enhanced, and the corresponding lengths are determined by field observation;

⑷ for roadbed slopes which have undergone freeze thawing and slumping, under the conditions of re-repairing and well-done slope scouring protection, the setting range takes the original slumping range as the standard, and the extension coverage range refers to item (1);

step four: determining the depth of the water collecting and draining pipe (converting into the length of the water collecting and draining pipe)

As shown in fig. 6, the water collecting and draining pipe is driven into the slope soil at a 3-5% outward inclination, the length of the water collecting and draining pipe is L, the maximum depth of one end of the water collecting and draining pipe driven into the soil from the slope surface is h, and the value of h is the set depth;

the freeze-thaw collapse depth is generally 20-70 cm, and the setting depth h of the water collecting and draining pipe is not less than the freeze-thaw collapse depth; the typical setting depth of the water collecting and discharging pipe is 40-70 cm; the relationship between the corresponding pipe length and the slope of the roadbed slope is shown in figure 2.

The setting depth h of the water collecting and discharging pipe is as follows:

⑴ in the third step, the water exposure range between layers is 60-70 cm within the range of extending 3m from left to right and 1m above and 1-2 m below the water exposure range, and the other part is 40-50 cm, namely the depth of the part with much water accumulation is correspondingly increased;

step six: driven into a water collecting and draining pipe

The hole at the soil inlet end of the water collecting and discharging pipe is wedged by a wood plug 4 and is wrapped by an iron sheet so as to prevent soil from entering the pipe; the exposed end of the drain pipe is padded by a wood block or a thick-wall metal sleeve and then is hit so as to prevent the end part of the drain pipe from being damaged; for hard soil, need use the preliminary pore-forming of hole puncher, the pore-forming aperture uses the external diameter of collection blast pipe as the standard, then squeezes into collection blast pipe. When the holes are preliminarily formed and the water collecting and draining pipe is driven into the hole, the holes are formed and driven into the hole according to the requirement of inclining outwards by 3-5 percent (the front section is high, the exposed near end is low), and the length of the exposed pipe end of the slope surface is not less than 10 cm;

step seven: finishing

The collection calandria that the inspection was finished installs in having debris such as earth to in time the sanitization, then expose the end (can not block up inside the collection calandria with geotechnological cloth temporary wrapping (otherwise difficult morals and manners, influence intraductal air flow), avoid follow-up domatic maintenance earth debris to get into occasionally, will naturally weather after this geotechnological cloth several months.

The second embodiment is as follows: in a specific embodiment, in the first step, the outer pipe 2 and the inner pipe 1 are made of metal (such as common steel pipe, galvanized pipe, cast iron pipe, galvanized iron sheet pipe, etc.) or plastic (such as PVC pipe, ABS pipe, polypropylene pipe, etc.).

The third concrete implementation mode: in a first specific embodiment, the roadbed slope freeze-thaw collapse prevention and treatment method based on dot-matrix assisted integration and drainage comprises the following steps of (3): drilling the pipe wall of the outer pipe 2 according to the diagram shown in fig. 3, determining and marking the drilling position of the pipe wall of the inner pipe 1 by adopting a nesting positioning or hole position measuring mode, and drilling the pipe wall of the inner pipe 1; at the moment, the left end of the outer pipe wall is perpendicular to the pipe wall, a positioning hole 3 with the diameter of about 2-3 mm penetrating through the pipe walls on the two sides of the inner pipe 1 and the outer pipe 2 is drilled at a position 30-50 cm away from the end part of the outer pipe 2, and an iron wire 6 is inserted for positioning during nesting.

The fourth concrete implementation mode: in the fourth step, in the arrangement mode of the upper depth and the lower depth, the depth of the upper depth is 60-70 cm, and the depth of the lower depth is 40-50 cm.

Example 1:

slope of excavation subgrade (cutting) slope of a certain highway is 1: 1.5, the length along the route direction is about 120m, and the slope surface length is about 14 m. At a point about 1/4 from the top of the slope, interlayer water appeared, which showed a clear wet mark, about 36cm wide, corresponding to a length of about 64m, with no running water. The slope soil is fine soil.

The method comprises the following steps: and manufacturing the melting-assisted water collection and drainage pipes with different lengths by referring to fig. 2 to 5.

Step two: and confirming the possibility of freeze-thaw collapse according to the actual situation of the roadbed slope.

Step three: the setting range of the auxiliary melting collecting and draining pipe is as follows: the water exposure range between layers was set as a reference, and the extension was 3m in the left-right direction, 2m in the upper direction and 5m in the lower direction.

The fourth step is that the setting depth of the water collecting and draining pipe is determined ① according to an empirical method, according to investigation, the average freezing and thawing collapse depth of the adjacent road sections on the same side of the road is 64cm, considering that the water accumulation layer of the side slope rises by about 6-20 cm during spring thawing after vegetation recovery, the setting depth of the water collecting and draining pipe is 60cm by referring to the similar surrounding collapse depth and the ice accumulation layer depth in the middle and upper ten days of 4 months, the stable Fs of the side slope of the road is not less than 1.25 according to the design specification of the roadbed, and the stable Fs of the side slope of the road is not less than 1.84 according to a mechanical method, and the stable Fs of the road is obtained according to a stability checking formula (according to the road foundation protection technical guideline of the road foundation of the province of Black Long Jiang or the road foundation design and construction technical specification of the seasonally frozen soil region), the stable Fs of the road slope of the road foundation is obtained according to the safety factor of the road foundation protection of the road foundation of the Black Long Jiangjiang province, or the road foundation design and construction technical specification of the seasonal frozen soil region, the road foundation, the stable Fs of the road slope of the road foundation, the section is obtained by the stable Fs, the stable.

Step five: two adjacent rows of water collecting and discharging pipes are arranged in a staggered manner from top to bottom, the arrangement depth is within the range of 60cm, and the arrangement distance is 2 m; the setting distance is 3m within the range of the setting depth of 40 cm.

Step six: holes are formed according to the outward inclination of about 4 percent and are driven into a water collecting and discharging pipe.

Step seven: and (5) checking and cleaning the interior of the water collecting and draining pipe, and wrapping the exposed pipe head by using single-layer geotextile and a glass fiber rope.

In addition, for the roadbed slope which needs to be subjected to construction such as slope scouring protection, the setting range of the water collecting and discharging pipe is measured and recorded in advance, and the method is implemented after the slope scouring protection construction is finished.

Claims

1. A roadbed slope freeze-thaw collapse prevention and control method based on dot matrix type assisted integration drainage is characterized by comprising the following steps: the method comprises the following specific steps:

⑴ the water collecting and draining pipe is formed by nesting an outer pipe (2) and an inner pipe (1);

⑵ the tube wall of the outer tube (2) is slotted, the inner tube (1) is round;

⑶ when the hole is opened, the hole positions of the inner tube (1) and the outer tube (2) should be aligned;

⑷ wrapping the outer wall of the inner pipe (1) with a double-layer reverse filtering type non-woven geotextile (5);

⑸, the inner pipe (1) is embedded into the outer pipe (2), the inner pipe (1) is rotated left and right to align with the positioning hole (3), then the iron wire (6) is inserted to penetrate through the water collecting and discharging pipe, and the two ends of the iron wire (6) need to be bent to avoid slipping;

⑹ the round hole at the tip of the water collecting and discharging pipe is sealed by a wooden plug (4), so as to prevent soil from entering the pipe when the water collecting and discharging pipe is driven into the soil;

step two: judging whether freeze-thaw collapse is possible on roadbed slope

Judging whether the roadbed slope has the possibility of shallow layer freeze-thaw collapse and the depth of the shallow layer freeze-thaw collapse by adopting a mechanical method or an empirical method; the mechanical method utilizes a freeze-thaw slump stability checking formula, a freeze-thaw slump stability safety coefficient is checked and calculated according to physical mechanical parameters of a side slope soil body and analyzed, when the safety coefficient is less than 1.25, the possibility of slumping exists, and the slumping depth is judged according to the position of a sliding surface; the empirical method is comprehensively judged according to the conditions of whether interlayer water is exposed on the slope surface of the roadbed side slope, whether the adjacent side slope slips or not, whether snow cover is formed in winter or not and whether water seepage is formed at the top of the slope or not; judging that shallow freeze-thaw slump is possible on a fine-grained soil slope with interlayer water exposure, a fine-grained soil slope with moist soil on the back and accumulated snow in winter and a slope with local slump, and taking the depth of the generated slump as a reference standard; when the non-collapse depth can be referred to, setting according to 70 cm;

⑶ for roadbed side slopes which have no obvious interlayer water signs but have downward water seepage at the top of the slopes, the arrangement range of the roadbed side slopes is based on the range of the height of the upper part of the roadbed side slopes from the tops of the slopes 1/3-1/2 while enhancing the interception and seepage prevention of water flow at the tops of the roadbed slopes;

⑷ for roadbed slopes which have undergone freeze-thaw collapse, under the conditions of re-repairing and well-done slope scouring protection, the setting range of the roadbed slopes takes the original collapse range as the standard, and the coverage range is extended according to the item (1) in the step;

the setting depth h of the water collecting and discharging pipe is as follows:

for ⑵ in the third step, the setting depth can be gradually transited in the upper part of the setting range of 40-50 cm and the lower part of the setting range of 60-70 cm, or the setting range is divided into an upper part and a lower part, a scheme of shallow in the upper part and deep in the lower part is adopted, and the setting depth is consistent in the horizontal direction;

step six: driven into a water collecting and draining pipe

The hole at the soil inlet end of the water collecting and discharging pipe is wedged by a wood plug (4) and is wrapped by an iron sheet; the exposed end of the drain pipe is padded by a wood block or a thick-wall metal sleeve and then is hit; for hard soil, a hole is formed by a puncher initially, the aperture of the formed hole is based on the outer diameter of the water collecting and discharging pipe, and then the hole is driven into the water collecting and discharging pipe; when the holes are preliminarily formed and the holes are punched into the water collecting and draining pipe, the holes are formed according to the requirement of inclining outwards by 3-5% and are punched, and the length of the exposed pipe end of the slope surface is not less than 10 cm;

step seven: finishing

2. The roadbed slope freeze-thaw collapse prevention and control method based on the dot matrix type assisted melting and water drainage, as claimed in claim 1, is characterized in that: in the first step, the materials used for the outer pipe (2) and the inner pipe (1) are metal or plastic.

3. The roadbed slope freeze-thaw collapse prevention and control method based on the dot matrix type assisted melting and water drainage, as claimed in claim 1, is characterized in that: in the step one (3), the positioning method of the inner pipe and the outer pipe comprises the following steps: the pipe wall of the outer pipe (2) is perforated, then the perforation position of the pipe wall of the inner pipe (1) is determined and marked by adopting a nesting positioning or hole position measuring mode, and then the pipe wall of the inner pipe (1) is perforated; at the moment, the left end of the outer pipe wall is perpendicular to the pipe wall, a positioning hole (3) which is about 2-3 mm in diameter and penetrates through the pipe walls on the two sides of the inner pipe (1) and the outer pipe (2) is formed in the position 30-50 cm away from the end part of the outer pipe (2), and an iron wire (6) is inserted for positioning during nesting.

4. The roadbed slope freeze-thaw collapse prevention and control method based on the dot matrix type assisted melting and water drainage, as claimed in claim 1, is characterized in that: in the fourth step, in the arrangement mode of the upper part with the depth and the lower part with the depth, the thickness of the upper part with the depth is 60-70 cm, and the thickness of the lower part with the depth is 40-50 cm.