CN113417183A

CN113417183A - Red clay roadbed and construction method

Info

Publication number: CN113417183A
Application number: CN202110845904.4A
Authority: CN
Inventors: 周小军; 郝春华; 蒋科; 曹毅; 王理吉; 林永胜; 刘家俊; 许智威; 胡伟
Original assignee: China Merchants Chongqing Communications Research and Design Institute Co Ltd
Current assignee: China Merchants Chongqing Communications Research and Design Institute Co Ltd
Priority date: 2021-07-26
Filing date: 2021-07-26
Publication date: 2021-09-21

Abstract

The invention discloses a red clay roadbed and a construction method, wherein the red clay roadbed comprises a embankment filling body, and the embankment filling body is formed by red clay fillers; the embankment filling body is externally coated with a composite liner for maintaining the water content of the red clay filler to be stable; and a base layer for draining water is laid below the embankment filling body. The invention has simple structure and simple and convenient construction, is beneficial to large-scale continuous operation, can fully utilize red clay filler, reduce the quantity of spoil and borrow earthwork, and relieve the balance contradiction of earthwork and stone, thereby achieving the aim of reducing the construction cost.

Description

Red clay roadbed and construction method

Technical Field

The invention relates to the field of roadbed filling, in particular to a red clay roadbed and a construction method.

Background

The red clay is high-plasticity clay which is formed by carrying out damp-heat reaction, weathering and lateritic treatment on carbonate parent rock and has brownish red, brownish yellow and the like colors. The red clay has a large number of cementing aggregate structures, so that the red clay shows special physical and mechanical properties. The special soil generally has the characteristics of high liquid limit, high plasticity, high water content, high pore ratio, higher strength and lower compressibility, is in a compact hard plastic state in a natural state, and cracks on the surface of a soil body even forms deep and long ground cracks when a small amount of water is lost, so that the overall strength of the soil body is reduced, the integrity of the soil body is damaged, and great harm is caused to various engineering constructions.

With the steady promotion of national economy and the rapid development of engineering construction, the problem of red clay filling cannot be avoided in the process of highway and urban road infrastructure. The red clay is widely distributed in wide lakes, Yugui and middle and lower reaches of Yangtze river in China, the thickness of the red clay is different in all regions, the thickness of the red clay is about 3-6 m in Guizhou region, the thickness of the red clay is generally 7-8 m in Yunnan region, and the thickness of the red clay is generally 10m in Hunan, Huxi and Guangxi regions. Taking an expressway in an area where red clay and secondary red clay are generally covered on the earth surface as an example, the line length is about 55 kilometers, and the filling requirement is about 140 ten thousand square, so that the method has the advantages that the filling requirement is huge, on one hand, no high-quality filler is available, on the other hand, the red clay serving as special soil does not meet the filling requirement, and the earth-rock balance contradiction is prominent. Therefore, a red clay roadbed filling structure and a construction method are urgently needed to solve the practical problem of filling shortage.

The red clay is adopted to directly fill roads, so that the defects of embankment cracking, slope peeling, slump slip, overlarge deformation and the like are easily caused, and the long-term stability of the roadbed is not facilitated. At present, the red clay filling problem solved by the engineering industry mainly has the following 2 aspects.

(1) And (3) filling and replacing waste soil: in the past, when a high-grade road embankment is filled, the red clay in the route range is mainly filled by spoil replacement, the treatment mode is easy to control in quality, and the construction method is simple. However, the excavation and abandonment of the red clay not only increase the newly-increased area of the spoil area, but also increase the transportation cost of the filler in the non-red clay area, the damage to the ecological environment in the soil taking and spoil process is great, and the complex challenge is caused to the engineering cost saving and the safe and reasonable use of resources.

(2) Physical or chemical modification: the physical or chemical modification is the treatment of the red clay doped with ash. The physical method is that the red clay is mixed with bonding materials such as broken stone, slag or gravel, and the overall strength and rigidity of the red clay are improved by utilizing the self strength and the generated frictional resistance of the materials; the chemical method is that cement, lime, additive and other chemical materials are added, a series of chemical reactions are carried out to absorb the moisture of the soil body and generate colloid flocculation substances, and a stable net rack structure is formed inside the red clay after a certain time of reaction, so that the compactibility, stability and integrity of the red clay are improved. At present, the ash doping treatment of red clay is mostly concentrated on indoor tests or engineering test section researches, and belongs to test properties; the most defects of the ash mixing treatment are that the mixing is difficult, the uniformity and compactness of the roadbed are greatly influenced by the uneven mixing, the filling quality of the roadbed is difficult to guarantee, and the method cannot be popularized on a large scale.

Based on the red clay roadbed and the construction method, the red clay resources are fully utilized, the long-term stability of the roadbed is guaranteed, and meanwhile the construction cost is saved.

Disclosure of Invention

In view of this, the present invention aims to overcome the defects in the prior art, and provide a red clay roadbed and a construction method thereof, which can make full use of red clay resources, ensure the long-term stability of the roadbed, and save the construction cost.

The red clay roadbed comprises a roadbed body, wherein the roadbed body comprises a embankment filling body and a composite liner which completely covers the embankment filling body; the embankment filling body comprises red clay filling; the composite liner comprises a reverse filter layer for preventing the particles of the embankment filling body from losing and an impermeable layer for preventing external moisture from entering the embankment filling body. Because the road matrix is wrapped in the composite liner, the red clay filler particles are protected by the inverted filter layer, and the impermeable layer prevents external moisture from entering the interior of the embankment filler, so that the soil strength and deformation of the red clay filler can be improved, the strength of the red clay filler meets the requirement of the embankment filler, and the soil strength and stability of the embankment filler are ensured; can also fully utilize red clay resources, reduce the quantity of soil taking and abandoning and protect the ecological environment within a certain range.

Further, the impermeable layer comprises clay protective layers and impermeable geomembranes which are alternately laid along the height direction of the road matrix. Wherein, the clay protective layer and the anti-seepage geomembrane can be respectively provided with one layer or a plurality of layers according to specific requirements. Specifically, if the clay protective layer is provided with two layers, the anti-seepage geomembrane is provided with two side layers and is alternately paved along the height direction of the road matrix; if the clay protective layer is provided with three layers, the anti-seepage geomembrane is provided with two layers, the clay protective layer is paved firstly, and then the anti-seepage geomembrane is paved, so that the clay protective layer and the anti-seepage geomembrane are alternately paved until the paving is finished. The clay protective layer has low permeability, can isolate the convection of internal air and external air and the communication of moisture, and enhances the soil body strength and stability of the embankment filling body.

Furthermore, a plurality of grooves for improving the friction force between the anti-seepage geomembrane and the clay protective layer are uniformly rolled on the surface of the anti-seepage geomembrane. The groove can enable the anti-seepage geomembrane to be engaged with the clay protective layer in an embedding and locking manner, and meanwhile, the anti-seepage geomembrane can improve the reinforcement effect of the anti-seepage geomembrane on the clay protective layer, so that the strength and the stability of the anti-seepage layer are further enhanced.

Furthermore, the impervious layer is laid between the inverted filter layer and the roadbed filling body. Further improve the effect that the barrier layer maintains the moisture content stability to red clay filling body.

Furthermore, the cross section of the embankment filling body is of a ladder-shaped structure, multiple layers of steps are arranged on two sides of the ladder-shaped structure, and clay is filled into the steps to form an inclined plane, so that the integrity of the composite liner and the embankment filling body is enhanced.

Furthermore, a substrate layer for draining water is laid below the roadbed body, the substrate layer has a flow guiding effect on underground water, and meanwhile, the composite pad on the upper portion of the substrate layer is protected.

Furthermore, water permeable pipes are uniformly distributed on two sides of the substrate layer, and each water permeable pipe comprises a drainage section communicated with the side ditch of the embankment and a water interception section extending into the substrate layer; the intercepting section is provided with a plurality of drain holes, and the intercepting section is coated with geotextile which can shield the drain holes. Wherein, the geotextile can prevent sand gravel from blocking the drain hole to influence the drainage of the permeable pipe.

The construction method of the red clay roadbed comprises

The method comprises the following steps: determining side piles and middle piles for embankment filling according to the design elevation and the actual ground elevation so as to control the width and the length of an embankment filling body;

step two: removing weeds, plant roots and other impurities on the original ground or the top surface of the cushion layer, and cleaning the surface to level; surface drainage is well done by combining with a permanent drainage design, and drainage ditches are paved in time after being excavated, so that the foundation and the slope toe are ensured not to accumulate water;

step three: excavating and filling a base layer on the base;

step four: laying a composite liner on the substrate layer for maintaining the water content of the red clay filler to be stable;

step five: according to the full width of the cross section of the embankment filling body, filling upwards layer by layer according to horizontal levels; (1) determining the loose paving thickness of each layer of red clay filler according to set data, and controlling the thickness and the width by hanging wires when the red clay filler is paved; (2) compacting the loosely laid red clay filler to ensure that the leveling requirement is met; repeating the steps (1) and (2) until the rolling of the whole embankment filling body is completed;

step six: and laying composite pads on two sides and the top of the embankment filling body.

Further, in the fourth step: the composite liner comprises an impermeable layer and a reverse filter layer which are sequentially paved along the height direction of the embankment filling body; the impermeable layer comprises a clay protective layer and an impermeable geomembrane, and the clay protective layer and the impermeable geomembrane are alternately paved along the height direction of the embankment filling body until the paving of the impermeable layer is completed; in the sixth step, the laying of the composite liner is the same as that in the fourth step.

Further, a water permeable pipe is embedded in the substrate layer, and the water permeable pipe comprises a drainage section and a water interception section with a drainage hole; the drainage section extends out of the substrate layer, and the water interception section is located in the substrate layer. The water of the basal layer enters the water intercepting section through the water discharging hole and then is discharged out of the basal layer through the water discharging section, so that excessive underground water in the basal layer is rapidly discharged, and the composite gasket paved on the basal layer is prevented from being influenced by the excessive underground water.

Furthermore, the composite liners on the two sides of the embankment filling body are covered with planting soil layers with enough thickness so as to prevent the damage of the growth of plant roots to the liners and the gnawing of rodents to the geomembranes; meanwhile, the greening requirement is met.

Further, the compaction in the fifth step (2) comprises three times of rolling, wherein the first rolling is static pressure; the second rolling is performed by adopting high-frequency and low-amplitude vibration rolling; and the rolling for the third time is static pressure, so that the compactness of the red clay filler can meet the requirement. The rolling method is generally divided into two types, one type is that a smooth wheel roller uses a smooth wheel to compact various building and road building materials, and the compaction is also called as static pressure; another type of vibratory roller uses its own weight and vibration to compact various construction and road materials, commonly referred to as vibratory compaction. The compaction degree of the embankment filling body can reach the specified requirement faster because the vibration rolling is most suitable for compacting various non-sticky soil, broken stones, broken stone mixtures and various asphalt concretes, the static pressure is mainly used for compacting the subgrade of soil and stone materials and compacting the base course of the pavement, and the static pressure and the vibration rolling are carried out alternately.

Further, in the fourth step, the upper end surface of the base layer is inclined towards two sides from the center line of the base layer. Is beneficial to the drainage of the base.

Further, in the sixth step, steps are formed between layers, and the steps incline towards the center line of the embankment filling body, so that the connection between the side part gasket and the embankment filling body is increased.

The invention discloses a red clay roadbed and a construction method, which have the beneficial effects that:

(1) according to the invention, red clay in the road area can be fully utilized as red clay filler, the amount of spoil earthwork and the amount of borrow earthwork are reduced, and the balance contradiction of earthwork and stone is greatly relieved, so that the purposes of reducing the construction cost, shortening the construction period and avoiding water and soil loss are achieved.

(2) The composite liner that inverted filter and barrier layer of adoption are constituteed can keep apart embankment inside and the external world, and the moisture content of packing maintains basic stability, stops red clay dehydration fracture influence, guarantees the long-term stability of road bed. The anti-seepage layer is formed by alternately overlapping and paving the clay protective layer and the anti-seepage geomembrane, and the strength and the stability of the red clay embankment are enhanced by means of the anti-seepage geomembrane, the clay protective layer and the effect of interlocking occlusion.

(3) The invention avoids the defect of uneven stirring in the red clay ash mixing improvement treatment, has simple structure, high efficiency and simple and convenient construction, can adopt a mechanical mode for the earthwork synthetic material and the filler paving, and is beneficial to large-scale continuous filling operation.

Drawings

The invention is further described below with reference to the following figures and examples:

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is an enlarged view of A in FIG. 1;

FIG. 3 is an enlarged view of B in FIG. 1;

FIG. 4 is an enlarged view of C in FIG. 1;

FIG. 5 is an enlarged view of D in FIG. 1;

FIG. 6 is a structural view of the water permeable pipe of the present invention;

fig. 7 is a schematic view of an impermeable geomembrane and a reverse filter geotextile of the present invention as laid;

FIG. 8 is a construction flow chart of the present invention.

In the figure, 1 is embankment filling body, 2 is a reverse filtration layer, 3 is an impermeable layer, 3-1 is a clay protective layer, 3-2 is an impermeable geomembrane, 5 is a substrate layer, 6 is a pavement structure layer, 7 is a planting soil layer, 8 is a platform drainage ditch, 9 is an embankment side ditch, 10 is a permeable pipe, 10-1 is a drainage section, 10-2 is a water interception section, 10-3 is a drainage hole, 11 is a composite liner, 11-1 is a top liner, 11-2 is an edge liner, 11-3 is a bottom liner, 12 is cement mortar, 13 is a buffer platform, 14 is a step,

15 is clay filler, 16 is guiding gutter.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and examples, wherein the terms "upper", "lower", "left", "right", "inner", "outer", and the like, refer to orientations and positional relationships that are based on the orientations and positional relationships shown in the drawings, which are used for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular manner, and thus should not be construed as limiting the present invention. The terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

As shown in fig. 1 to 7, the red clay roadbed in the embodiment includes a roadbed body. The roadbed comprises an embankment filling body 1 and a composite liner 11 which completely covers the embankment filling body 1. The embankment filling body 1 mainly adopts red clay filler 15; the composite liner 11 includes a reverse filter layer 2 and a barrier layer 3. The anti-seepage layer 3 is laid on the anti-filtration layer 2 (along the height direction of the embankment filling body 1) and is used for protecting the red clay filling body and preventing soil particles from losing. The composite liner 11 completely covers the embankment filling body 1 means that the composite liner 11 comprises a top liner 11-1 covering the embankment filling body 1, side liners 11-2 covering two sides of the embankment filling body 1 and a bottom liner 11-3 laid below the embankment filling body 1, and the top liner 11-1, the side liner 11-2 and the bottom liner 11-3 which are adjacent are connected to completely cover the embankment filling body 1, so that external moisture is prevented from entering the embankment filling body 1, the water content of the red clay filler 15 is kept stable, the soil body strength and deformation of the red clay filler 15 are improved, and the soil body strength and stability of the embankment filling body 1 are further enhanced; can also fully utilize red clay resources, reduce the quantity of soil fetching and abandoning and protect the ecological environment within a certain range. The pavement structure layer 6 is laid on the pavement base body, namely on the top liner 11-1; the edge liner 11-2 is covered with a planting soil layer 7 with enough thickness, so that the greening requirement is met, and meanwhile, the liner is prevented from being damaged by the growth of plant roots and the geomembrane is prevented from being gnawed by rodents.

In this embodiment, the impermeable layer 3 is formed by alternately laying the clay protective layer 3-1 and the impermeable geomembrane 3-2 along the height direction of the road matrix, so that the impermeable geomembrane 3-2 can reinforce the soil body of the clay protective layer 3-1, thereby reducing the consumption and thickness of the clay protective layer 3-1. The low permeability of the clay protective layer 3-1 is matched with the anti-seepage geomembrane 3-2, so that the waterproof effect of the anti-seepage layer 3 can be improved. Preferably, the clay protective layer 3-1 has three layers, the impermeable geomembrane 3-2 has two layers, the clay protective layer 3-1 is firstly paved on the road matrix, the impermeable geomembrane 3-2 is paved, and the clay protective layer 3-1 … is paved so as to alternately pave the clay protective layer 3-1 and the impermeable geomembrane 3-2 until the paving is finished. Preferably, the thickness of the clay protective layer 3-1 is not less than 20cm, and the thickness of the impermeable geomembrane 3-2 is not less than 1.5 mm. The thickness of the top liner 11-1 is not less than 80cm for light, medium and heavy traffic roads or urban roads, and the thickness of the top liner 11-1 is required to be not less than 120cm for extra heavy and extremely heavy traffic.

Wherein, the anti-seepage geomembrane 3-2 can select a polyethylene film (PE), a polypropylene film (PP), a high density polyethylene film (HDPE), a polyester film (PES), a polyacrylonitrile film (PAC) and a polyamide film (PA) according to different raw materials. High density polyethylene geomembranes (HDPE) are preferred in this embodiment. The reverse filter layer 2 may be made of reverse filter geotextile (generally needle-punched non-woven geotextile), and the raw materials may be polyester fiber cloth (PET), polypropylene (PP), Polyethylene (PE), etc., and in this embodiment, polyester geotextile (PET) is preferred.

In this embodiment, the clay protection layer 3-1 has a plurality of grooves uniformly distributed on the surface thereof for increasing the friction between the impermeable geomembrane 3-2 and the clay protection layer 3-1. Specifically, after the wool feet are uniformly rolled on the surface of the clay protective layer 3-1 to form grooves, the impermeable geomembrane 3-2 is laid on the clay protective layer, and then the clay protective layer 3-1 is laid, the steps are sequentially alternated, and the wool feet are rolled after the clay protective layer 3-1 is laid each time, so that the impermeable geomembrane 3-2 and the clay protective layer 3-1 are engaged in an interlocking manner, and the strength and the stability of the impermeable layer 3 are further enhanced.

In this embodiment, the impermeable layer 3 is laid between the inverted filter layer 2 and the roadbed filling. In the embodiment, the reverse filter layer 2 is made of reverse filter geotextile, and the edges of the anti-seepage geomembrane 3-2 and the reverse filter geotextile are provided with set folding lengths so as to prevent the anti-seepage geomembrane 3-2 and the reverse filter geotextile from being pulled out or retracted from the soil layer. Preferably, the length of the fold L is not less than 1.5m, and the fold F needs to be compacted, as shown in FIG. 7.

In this embodiment, the cross section of the embankment filling body 1 is a ladder-shaped structure, and multiple layers of steps 14 are arranged on two sides of the ladder-shaped structure, preferably, the steps 14 are inward-inclined steps 14, that is, the steps 14 on two sides are inclined towards the center line of the embankment body. The step 14 is filled with clay filler 15 to form an inclined plane, and the edge pad 11-2 is laid on the inclined plane formed after the filling of the ladder-shaped structure. Due to the fact that the clay filler 15 is used for filling, the clay filler 15 is combined with the clay protection layer 3-1 in the edge pad 11-2, and integrity of the edge pad 11-2 and the embankment filling body 1 is enhanced. The width of the step 14 is not less than 2m, the step 14 is inclined by 2% -4% facing the embankment filling body 1, and the preferred value is 4% in the embodiment. The top width S of the edge pad 11-2 is not less than 1.5m to facilitate the mechanized compaction of the top of the edge pad 11-2 during construction.

In this embodiment, a base layer 5 for draining water is laid below the road base body, as shown in fig. 5, both sides of the base layer 5 extend out of the edge pad 11-2, and the upper end surfaces of the extending parts are leveled and closed by cement mortar 12. Preferably, the base layer 5 is a gravel protective layer, and other water-permeable materials such as crushed stones may be used for the base layer 5.

The width of the cross section of the first step 14 is larger than that of the cross sections of the other steps 14, after the edge part liner 11-2 is laid, a buffering platform 13 is formed at the first step 14, and a platform drainage ditch 8 is arranged on the buffering platform 13. Two sides of the substrate layer 5 extending out of the edge pad 11-2 are provided with embankment side ditches 9, and the bottoms of the embankment side ditches 9 are lower than the substrate layer 5. The platform drainage ditches 8 are communicated with the embankment side ditches 9 through a plurality of diversion trenches 16, and the diversion trenches 16 are distributed along the length direction of the embankment filling body 1.

In the present embodiment, the first and second electrodes are,the parts of the two sides of the substrate layer 5 extending out of the edge part gaskets 11-2 are uniformly provided with water permeable pipes 10, and each water permeable pipe 10 comprises a drainage section 10-1 communicated with the embankment side ditch 9 and a water interception section 10-2 extending into the substrate layer 5. The water intercepting section 10-2 is provided with a plurality of drain holes 10-3, and the water intercepting section 10-2 is coated with geotextile which can shield the drain holes 10-3. Specifically, the water permeable pipe 10 is preferably a PVC plastic pipe, and 400g/m is adopted as geotextile²A non-woven geotextile. In this example, the diameter of the drainage hole 10-3 is not less than 100mm, and the distance between two adjacent drainage holes 10-3 is 75 mm. After the drain hole 10-3 is shielded by the geotextile, sand-proof gravel can block the drain hole 10-3 so as to influence the drainage of the permeable pipe 10.

Before construction, the following steps are carried out:

1. determining an experimental road section and obtaining construction data: the test road section is carried out according to geological conditions and a roadbed section form, and the length of the test road section is not less than 200 m.

(1) Determining the optimal water content omega 2 and the maximum dry density after the embankment filler is compacted in the laboratory through a heavy compaction test and a CBR strength test in the laboratory;

(2) in a field test section, the thickness of each loose paving of the red clay filler is 30cm, the red clay filler is rolled after being paved and leveled, the used road roller is not less than 18t, and the rolling times are generally controlled to be 6-9 times. Wherein, the water content omega 1 after the red clay filler is compacted in the test road section is required to be ensured to be omega 2 +/-2 percent,

(3) and measuring the compaction degree after each rolling.

Specifically, for example, in a highway, the red clay filler at the roadbed is required to have a degree of compaction not less than 96%, the red clay filler at the upper embankment is required to have a degree of compaction not less than 94%, and the red clay filler at the lower embankment is required to have a degree of compaction not less than 93%. And if the red clay packing compactness of each part meets the requirement, determining the mechanical specification, rolling times, the loose paving thickness, the optimal water content range during rolling and the like according to the test road section to start large-scale construction.

If the red clay filler compaction degree of each part does not meet the requirement, repeating the steps (1) - (3) by measures of reducing the loose paving thickness of the red clay filler, increasing the specification of the rolling machine, increasing the rolling times and the like until the red clay filler compaction degree requirement meets the requirement.

2. Preparation work: preparing a construction machine, selecting a proper mechanical combination, a proper mechanical specification, a proper rolling pass, a proper rolling speed, a proper loose paving thickness, a proper water content range during rolling and the like through a test section; simultaneously detecting the entrance filler, the geotechnical liner material and the like;

the construction method of the red clay roadbed is shown in figure 8,

the method comprises the following steps: measuring and lofting by adopting a total station instrument or a GPS instrument according to the designed elevation and the actual ground elevation, determining side piles and middle piles for filling the embankment, marking the layer thickness on the side piles and connecting the side piles by using nylon ropes so as to control the filling width and the layer thickness;

step two: removing weeds, plant roots and other impurities on the original ground or the top surface of the cushion layer, and leveling the cleaned surface, wherein the cleaning thickness in the embodiment is at least 30 cm; the surface drainage is well done by combining the permanent drainage design, the drainage ditch is paved in time after being excavated, and meanwhile, the water accumulation of the substrate and the slope toe is avoided;

step three: the original ground is cleaned and excavated to 30-50 cm, and the depth is preferably 30cm in the embodiment. And leveling the excavated surface by a bulldozer and a grader, compacting the excavated surface by the road roller to a degree of compaction not less than 90%, and filling a basal layer.

Step four: laying a composite liner on the substrate layer, wherein the composite liner laid on the substrate layer is a top liner;

step five: according to the full width of the cross section of the embankment filling body, filling upwards layer by layer according to horizontal levels;

(1) the thickness and the width are controlled by hanging lines when the red clay fillers are paved, and the loose paving thickness of each layer of the red clay fillers is determined according to the construction data of the test road section. After the red clay filler is spread, a bulldozer is used for pushing the red clay filler from high to low according to the designed longitudinal slope, and the red clay filler is pushed back and forth repeatedly to achieve the leveling requirement.

(2) And compacting the red clay filler after loose paving. Specifically, under the condition that a conventional vibratory roller is used as a compaction machine, the loose paving thickness of the red clay filler is not more than 40 cm;

repeating the steps (1) and (2) until the rolling of the whole embankment filling body is completed;

step six: and laying composite pads on two sides and the top of the embankment filling body, wherein the composite pads laid on the two sides of the embankment filling body are edge pads, and the composite pads laid on the top of the embankment filling body are top pads.

In this embodiment, in the fourth step and the sixth step: the composite liner comprises an impermeable layer and a reverse filter layer which are sequentially paved along the height direction of the embankment filling body; the impermeable layer comprises a clay protective layer and an impermeable geomembrane, and the clay protective layer and the impermeable geomembrane are alternately paved along the height direction of the embankment filling body until the impermeable layer is paved. Preferably, the clay protective layer has three layers, and the impermeable geomembrane has two layers, wherein the clay protective layer is laid firstly during construction, and the impermeable geomembrane is laid after the clay protective layer is pressed and the compactness is detected to be qualified, and the clay protective layer and the impermeable geomembrane are alternately laid until the impermeable layer is finished. When the impermeable geomembrane is laid, the impermeable geomembrane needs to be straightened, smoothly and tightly attached to the clay protective layer, and cannot be twisted or wrinkled. And after the impermeable layer is laid, laying a reverse filtering layer. The reverse filtering layer adopts reverse filtering geotextile. Preferably, after the compactness of the first clay protective layer is detected to be qualified, grinding the first clay protective layer by using sheep feet to ensure that a plurality of grooves are uniformly distributed on the first clay protective layer; laying a first anti-seepage geomembrane layer, laying a second clay protective layer, and rolling by using sheep feet after the compactness is detected to be qualified; laying a second anti-seepage geomembrane layer, laying a third clay protective layer, and rolling by using sheep feet after the compactness is detected to be qualified; and finally laying the reverse filtration geotextile (i.e. the reverse filtration layer). The groove formed by grinding the sheep feet can enable the anti-seepage geomembrane or the reverse filtering geotextile to be interlocked with the clay protective layer, and the clay protective layer can be further subjected to reverse filtering reinforcement.

Wherein, (1) the construction steps of the anti-seepage geomembrane are as follows: cutting → alignment → pressing → cleaning dust → welding test → welding → detection → acceptance. Specifically, the impermeable geomembrane is preferably a High Density Polyethylene (HDPE) geomembrane with the thickness of 1.5mm, the overlapping part of the impermeable geomembrane is not less than 10cm, and (2) the construction step of the reverse filtering layer is a reverse filtering geotextile: cutting → alignment→ pressing film → cleaning dust → welding test → welding → detection → acceptance; the reverse-filtering geotextile is preferably 400g/m²The nonwoven geotextile. The folding length L of the impermeable geomembrane and the non-woven geotextile is not less than 1.5 m. And the minimum joints of the anti-seepage geomembrane and the anti-filtration geotextile are ensured, the cutting is reasonable, the pulling is avoided, and the trial welding is firstly carried out before the formal welding of the heat welding machine, and then the large-area construction is carried out, so that the welding quality of the welding seam is ensured. (3) The clay protective layer should not contain sharp objects such as round gravel, corner gravel, crushed stones, etc. which can damage the impermeable geomembrane and the reverse filtration geotextile.

In the fourth step, the thickness of the clay protective layer in the bottom liner is not less than 20cm, the compaction degree is determined according to the highway grade and the position, specifically, for the highway, the compaction degree requirement of the clay protective layer at the roadbed is not less than 96%, the compaction degree requirement of the clay protective layer at the upper embankment is not less than 94%, and the compaction degree requirement of the clay protective layer at the lower embankment is not less than 93%.

And step six, straightening and smoothing the anti-seepage geomembrane and the anti-filtration geotextile when the anti-seepage geomembrane and the anti-filtration geotextile are laid, extending from the lowest position to the high position, and simultaneously clinging to the clay protective layer below the anti-seepage geomembrane and the anti-filtration geotextile. For the highways or urban roads of light, medium and heavy traffic, the thickness of the top liner is not less than 80 cm; extra heavy and extremely heavy traffic requires that the top liner thickness is not less than 120cm and the edge liner width is not less than 150 cm. And paving a road surface structural layer after the construction and detection of the top liner are qualified.

In this embodiment, pre-buried pipe of permeating water in the stratum basale, it is specific, the both sides of stratum basale are along pre-buried pipe of permeating water of embankment filling body length direction every certain interval. The water permeable pipe comprises a water drainage section and a water interception section with a water drainage hole. The water interception section is positioned in the substrate layer, and the drainage section extends out of the substrate layer and is communicated with the embankment side ditch for guiding the underground water. In this embodiment, the water permeable pipe is preferably a PVC plastic drain pipe.

In the sixth embodiment, after the edge liner is laid, the edge liner needs to be covered with a planting soil layer with a sufficient thickness to prevent the liner from being damaged by the growth of plant roots and prevent rodents from gnawing the geomembrane.

In this embodiment, the step five (2) of compacting the red clay filler includes three times of rolling, and the first rolling adopts a smooth-wheel road roller to perform static pressure on the red clay filler. And the second rolling is performed by adopting a high-frequency and low-amplitude vibration road roller to perform vibration rolling, the rolling sequence is performed from two sides to the center, the overlapping width between wheel tracks is controlled to be not less than 1/3 wheel tracks, the front and rear adjacent sections are longitudinally overlapped for 1.0-2.0 m, and the rolling process needs no dead angle, no under-pressure and no pressure leakage. The number of passes is increased appropriately for the border or interface. And the third rolling adopts the static pressure of a smooth-wheel road roller. And the rolling pass and the rolling speed are determined by the construction data of the test road section. After rolling, finishing the embankment filling body by adopting manpower or an excavator, and ensuring the compact embankment filling body and smooth linear shape;

in this embodiment, in the fourth step, the upper end surface of the substrate layer is inclined to both sides along the central line of the substrate layer, so as to form an end surface with a middle portion higher than both sides. The substrate layer is preferably a protective layer of gravel for diversion of groundwater and protection of the underlying liner. Wherein the thickness of the gravel protective layer is not less than 50cm, and the loose thickness of the gravel protective layer is within 40 cm; and the quality of the gravel is strictly controlled in the construction, specifically, the gravel is clean, and the permeability coefficient is not less than 5 multiplied by 10^-3cm/s, the mud content should not be more than 5%, and the fineness modulus should not be less than 2.7.

In this embodiment, in step six, form the step between the layer, the step inclines towards embankment filling body central line, and this step adopts clay filling to make the both sides of embankment filling body be the slope, and is preferred, and this clay is the same with the material of clay protective layer, lays limit liner back, does benefit to the linking that increases clay protective layer and embankment filling body in the limit liner.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that 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, and all of them should be covered in the claims of the present invention.

Claims

1. The utility model provides a red clay road bed which characterized in that: the road foundation comprises a road foundation body, wherein the road foundation body comprises a embankment filling body and a composite liner which completely covers the embankment filling body; the embankment filling body comprises red clay filling; the composite liner comprises a reverse filter layer for preventing the particles of the embankment filling body from losing and an impermeable layer for preventing external moisture from entering the embankment filling body.

2. The red clay subgrade of claim 1, wherein: the impermeable layer comprises clay protective layers and impermeable geomembranes which are alternately laid along the height direction of the road matrix.

3. The red clay subgrade of claim 2, wherein: and a plurality of grooves for improving the friction force between the anti-seepage geomembrane and the clay protective layer are uniformly distributed on the surface of the anti-seepage geomembrane.

4. The red clay subgrade of claim 1, wherein: and the impermeable layer is laid between the inverted filter layer and the embankment filling body.

5. The red clay subgrade of claim 1, wherein: the cross section of the embankment filling body is of a ladder-shaped structure, multiple layers of steps are arranged on two sides of the ladder-shaped structure, and clay filler is filled at the steps to form an inclined plane.

6. The red clay subgrade of claim 1, wherein: and a base layer for draining water is laid below the road base body.

7. The red clay subgrade of claim 1, wherein: the two sides of the substrate layer are uniformly provided with water permeable pipes, and each water permeable pipe comprises a drainage section communicated with the side ditch of the embankment and a water interception section extending into the substrate layer; the intercepting section is provided with a plurality of drain holes, and the intercepting section is coated with geotextile which can shield the drain holes.

8. The construction method of the red clay roadbed is characterized by comprising the following steps: comprises that

step two: cleaning and leveling the construction bottom surface; surface drainage is well performed by combining a permanent drainage design;

step three: excavating and filling a base layer on the base;

step four: laying a composite liner on the substrate layer;

step five: according to the full width of the cross section of the embankment filling body, filling upwards layer by layer according to horizontal levels; (1) determining the loose paving thickness of each layer of red clay filler; (2) compacting the loosely laid red clay filler; repeating the steps (1) and (2) until the rolling of the whole embankment filling body is completed;

9. The construction method according to claim 8, wherein: in the fourth step: the composite liner comprises an impermeable layer and a reverse filter layer which are sequentially paved along the height direction of the embankment filling body; the impermeable layer comprises a clay protective layer and an impermeable geomembrane, and the clay protective layer and the impermeable geomembrane are alternately paved along the height direction of the embankment filling body until the paving of the impermeable layer is completed;

in the sixth step, the laying of the composite liner is the same as that in the fourth step.

10. The construction method according to claim 8, wherein: in the third step, a water permeable pipe is embedded in the substrate layer, and the water permeable pipe comprises a drainage section and a water interception section with a drainage hole; the drainage section extends out of the substrate layer, and the water interception section is located in the substrate layer.

11. The construction method according to claim 8, wherein: and in the sixth step, planting soil layers cover the composite linings on the two sides of the embankment filling body.

12. The construction method according to claim 8, wherein: the compaction in the step five (2) comprises three times of rolling, wherein the first rolling is static pressure of the embankment filling body; the second rolling is performed by adopting high-frequency and low-amplitude vibration rolling; the third pass was static pressure.

13. The construction method according to claim 8, wherein: in the fourth step, the upper end surface of the base layer inclines towards two sides along the center line of the base layer.

14. The construction method according to claim 9, wherein: and step six, forming steps between layers, wherein the steps incline towards the center line of the embankment filling body.