CN113737593B - Highway subgrade widening structure - Google Patents
Highway subgrade widening structure Download PDFInfo
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- CN113737593B CN113737593B CN202110993685.4A CN202110993685A CN113737593B CN 113737593 B CN113737593 B CN 113737593B CN 202110993685 A CN202110993685 A CN 202110993685A CN 113737593 B CN113737593 B CN 113737593B
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C3/00—Foundations for pavings
- E01C3/04—Foundations produced by soil stabilisation
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D27/00—Foundations as substructures
- E02D27/10—Deep foundations
- E02D27/12—Pile foundations
- E02D27/16—Foundations formed of separate piles
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2300/00—Materials
- E02D2300/0084—Geogrids
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Abstract
The invention discloses a highway subgrade widening structure, which relates to the technical field of subgrade widening and comprises a plurality of groups of first structures, a group of second structures, a pavement structure layer and a plurality of vertical piles perpendicular to a loess stratum, wherein the first structures, the second structures and the pavement structure layer are sequentially arranged from bottom to top; each group of first structures comprises a geogrid, a cement soil layer and a newly filled roadbed which are sequentially arranged from bottom to top; each group of first structure bodies is close to the excavation surface of the old roadbed excavation step; the second structure body comprises a geogrid and a cement layer which are sequentially arranged from bottom to top; the second structure body is close to the excavation surface of the old roadbed excavation step; the bottom surface of each cement soil layer is provided with a groove; the groove is close to the excavation surface of the old roadbed excavation step; the pile top of the vertical pile body is tightly attached to the bottom surface of the bottom geogrid; the pile bottom of the vertical pile body is positioned in the loess stratum. The method can effectively control the post-construction settlement of the new roadbed and can also ensure the stability of the old roadbed.
Description
Technical Field
The invention relates to the technical field of roadbed widening, in particular to a highway roadbed widening structure.
Background
The loess area highway subgrade widening project has a plurality of technical problems, and longitudinal cracks on the pavement, uneven settlement, fluctuation of the road surface and even integral instability of the widened part are easily caused by poor treatment of loess due to the collapsibility of loess. In actual engineering, foundation treatment is carried out in a replacement and filling mode, and subgrade settlement cannot be effectively prevented. If the reinforced concrete pile, the prestressed pipe pile and other rigid pile composite foundations are adopted, the reinforcing strength of the widened part of foundations is too high, the road surface is reversely sloped or concave, the road surface is deformed, water drainage is not smooth, and driving safety is further damaged. Therefore, a new structure which can effectively control the post-construction settlement of a new roadbed and can also ensure the stability of an old roadbed is urgently needed in roadbed widening engineering.
Disclosure of Invention
The invention aims to provide a highway subgrade widening structure, which can effectively control the post-construction settlement of a new subgrade and ensure the stability of an old subgrade.
In order to achieve the purpose, the invention provides the following scheme:
a highway subgrade widening structure is arranged on the top surface of a loess stratum outside a side slope on one side of an old subgrade;
the structure comprises a plurality of groups of first structural bodies, a group of second structural bodies, a pavement structural layer and a plurality of vertical pile bodies vertical to the loess stratum, wherein the first structural bodies, the second structural bodies and the pavement structural layer are sequentially arranged from bottom to top;
each group of first structure bodies comprises a geogrid, a cement soil layer and a newly filled roadbed which are sequentially arranged from bottom to top; each group of first structure bodies is close to the excavation surface of an old roadbed excavation step; the old roadbed excavation step is a step excavated from top to bottom on a side slope of the old roadbed;
the second structure body comprises the geogrid and the cement soil layer which are sequentially arranged from bottom to top; the second structure body is close to the excavation surface of the old roadbed excavation step;
the bottom surface of each cement soil layer is provided with a groove; the groove is close to the excavation surface of the old roadbed excavation step;
the pile top of the vertical pile body is tightly attached to the bottom surface of the geogrid at the bottommost layer; the pile bottom of the vertical pile body is located inside the loess stratum.
Optionally, the structure further comprises a drain;
the escape canal sets up in the bottom loess stratum of 70cm department outside the geogrid the top surface.
Optionally, the geogrid is a double-layer laid biaxial tension plastic geogrid; the laying gradient of the geogrid is parallel to the road surface.
Optionally, the geogrid is fixed by U-shaped anchors or U-shaped staples.
Optionally, the step surface of the old roadbed excavation step has an inclined gradient of 2% towards the central part of the step surface.
Optionally, the vertical pile body is a micro-lime soil pile.
Optionally, a plurality of the vertical piles are arranged in a quincunx shape.
Optionally, the new roadbed is loess.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
according to the highway subgrade widening structure disclosed by the invention, the combined action of the geogrid and the cement soil layer has a remarkable limiting effect on the settlement of a newly filled subgrade; the newly filled roadbed is filled on the old roadbed excavation step in a layered mode, so that the integrity and the stability of the new roadbed and the old roadbed are improved; the synergistic effect of the geogrid, the cement soil layer and the original stable loess stratum of the lowest layer of the newly filled roadbed has the capability of controlling the roadbed settlement difference; the strength and bearing capacity of the consolidated foundation under the side slope of the old roadbed are enhanced by the synergistic effect of the geogrid, the cement soil layer, the original stabilized loess stratum and the vertical pile body, the settlement of the newly filled roadbed under the action of self weight is reduced, and the foundation treatment cost is greatly reduced when the new roadbed and the old roadbed are spliced; the grooves arranged at the joints of the new and old roadbeds enhance the splicing capacity of the joints of the new and old roadbeds through the synergistic action of the geogrids and the cement soil layers, so that the overall connecting capacity of the new and old roadbeds is remarkably improved, and the soil body at the joints of the new and old roadbeds is prevented from sliding; the geogrid is laid on the steps of the newly filled roadbed, a cement soil layer is filled on the geogrid, and then a soil body of the newly filled roadbed is filled in a circulating filling mode, so that the property of small compression deformation of the geogrid cement soil layer is fully utilized, and the settlement of the newly filled roadbed is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a vertical sectional view of an embodiment of a highway subgrade widening structure according to the present invention;
fig. 2 is a schematic view of pile arrangement adopted by the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a highway subgrade widening structure, which can effectively control the post-construction settlement of a new subgrade and ensure the stability of an old subgrade.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a vertical sectional view of an embodiment of the widening structure of the highway subgrade according to the invention. Referring to fig. 1, the highway substructure widening structure is provided on the top surface of a loess formation 2 outside a slope on one side of an old roadbed 1.
This highway subgrade broadens structure includes the first structure of multiunit, a set of second structure and the road surface structural layer 6 that set gradually from bottom to top to and a plurality of vertical piles 11 of perpendicular to loess stratum 2.
Each group of first structures comprises a geogrid 3, a cement soil layer 4 and a newly filled roadbed 5 which are sequentially arranged from bottom to top; each group of first structure bodies is close to the excavation surface of the old roadbed excavation step 7; the old roadbed excavation step 7 is a step excavated from top to bottom on the side slope of the old roadbed 1. After the old roadbed 1 side slope is cleared of loose soil, the old roadbed is excavated into a step shape, the step height is 2.5 meters, and the step length is 3 meters. The newly filled roadbed 5 is loess, namely a newly filled soil body. A cement soil layer 4 is filled on the geogrid 3; and the newly filled roadbed 5 is filled between the upper cement soil layer and the lower cement soil layer 4 and filled to the excavation step 7 and the groove 10 of the old roadbed. A newly filled roadbed 5 (soil body of the newly filled roadbed) is filled on the cement soil layer 4 and is fully tamped in the filling process; the newly filled roadbed 5 is filled to the upper step surface and the groove 10; the top surface of the newly filled roadbed 5 is flush with the step surface and the groove surface at the joint. The cement soil layer 4 and the newly filled roadbed 5 are alternately filled; and after the cement soil layer 4 is filled, filling a newly filled roadbed 5, and sequentially and circularly constructing until the bottom surface of the cement soil layer 4 filled at the lower part of the pavement structure layer 6. Wherein the excavation surface is a vertical surface of an old roadbed excavation step 7; the step surface is the horizontal surface of the old roadbed excavation step 7.
The second structure body comprises a geogrid 3 and a cement soil layer 4 which are arranged from bottom to top in sequence; the second structure body is close to the excavation surface of the old roadbed excavation step 7.
The bottom surface of each cement soil layer 4 is provided with a groove 10; the groove 10 is close to the excavation surface of the old roadbed excavation step 7. The groove 10 is a groove at the joint of the old and new roadbeds, the groove 10 is formed by excavating the joint of the old and new roadbeds, the slope line of the 1 side of the old roadbeds is positioned inside the groove 10, and the width of the groove is 3 times of the pile diameter of the vertical pile body 11 and 2 times of the pile distance of the vertical pile body 11. The invention arranges a groove 10 at the joint of the new and old roadbed and fills the groove with cement soil; the thickness of the cement soil filling of the groove 10 at the joint is the same as the thickness of the cement soil laying at the step, and the filling width of the groove 10 at the new and old roadbed is not less than 1.5 m.
The pile top of the vertical pile body 11 is tightly attached to the bottom surface of the bottom geogrid 3; the pile bottom of the vertical pile body 11 is positioned inside the loess ground layer 2. The vertical pile body 11 is a micro-lime soil pile. The plurality of vertical piles 11 are arranged in a quincunx shape (quincunx arrangement), as shown in fig. 2. The vertical pile body 11 is driven into the loess stratum 2, and the pile top is flush with the top surface of the loess stratum 2 outside the slope of the old roadbed 1.
The highway subgrade widening structure also comprises a drainage ditch 9; the drainage ditch 9 is provided on the top surface of the loess formation 2 at a position 70cm outside the lowermost geogrid 3. The drainage ditch 9 is positioned outside the slope of the newly filled roadbed 5 and the old roadbed 1 and is embedded into the loess stratum 2. When the drainage ditch 9 adopted by the invention is constructed, the drainage ditch 9 is arranged 70cm outside the slope toe of the old roadbed and the newly filled roadbed and is embedded into the loess stratum 2.
The geogrid 3 is a two-way stretch plastic geogrid laid in double layers; the laying (paving) gradient of the geogrid 3 should be parallel to the road surface. The geogrid 3 is laid on the old roadbed excavation step 7 and the groove 10. When a cement soil layer 4 is filled, the geogrid 3 is laid on the lower layer firstly, the step surface of the step 7 excavated from the old roadbed is laid to the slope of the newly filled roadbed 5 in a full-length mode, and then the cement soil layer 4 is filled. The geogrid 3 is fixed through U-shaped anchoring nails 8 or U-shaped fixing nails. The U-shaped anchor bolts 8 are arranged at intervals of 60cm, the used steel bars are phi 8 steel bars, and the depth of the anchoring section in the soil is 30 cm. The geogrid 3 is laid along the old roadbed excavation step 7 and the groove 10 at the joint of the new roadbed and the old roadbed and is laid to the side slope of the new roadbed; the geogrid 3 is a bi-directional geogrid laid in double layers, the lap joint width of the geogrid is not less than 20cm, and the geogrid is anchored by U-shaped anchors and U-shaped fixing anchors; wherein, the lapping refers to lapping between two geogrids; the geogrid 3 needs to adopt a product with high strength and ageing resistance; the geogrid 3 is laid on the step surface part and is not less than 3.5m, the laying stress is leveled, and the maximum grain diameter of the filler within 8cm from the geosynthetic material (geogrid) is not more than 60 mm.
The roadbed is widened by excavating the steps; the height of old roadbed excavation step 7 is 3m, and there is 2% inward sloping in the step. The step surface of the old roadbed excavation step 3 has an inclined gradient of 2% towards the center of the step surface.
The pile length L of the vertical pile body 11 adopted by the invention meets the following requirement:
the above formula ensures that the settlement of the pile-net composite foundation is within the range allowed by the specification, and is applicable to all vertical pile bodies 11. In the formula: psi is an empirical coefficient of pile foundation settlement calculation; n is the calculated layering number of the soil layer below the pile end plane; a is the number of cement filling layers; gamma ray c Is the gravity of the cement soil; h c The filling thickness of the cement soil layer; gamma is the soil gravity; h' i The thickness of the ith layer of the new filling layer; e si The compressive modulus of the ith layer of the soil layer under the pile end plane in the action section from the self-weight stress to the self-weight stress plus the additional stress; h is i For pile end to be flatThickness of the ith sub-layer of the subsurface soil layer; alpha is alpha i Is an additional stress factor; a is the action area of the bottom surface of the foundation; l is the pile length of the vertical pile body; gamma 0 is the average gravity of pile and soil, and the buoyancy should be deducted from the part below the ground water level.
The pile length (the pile length of the roadbed) L of the vertical pile body 11 adopted by the invention also meets the following requirement:
f＝k1λ1m(β1SaqL+β 2 ApR)+k2λ2(1-m)ps f
in the formula, k 1 The correction coefficient is different between the actual limit bearing capacity and the free bearing capacity of the pile body; beta is a beta 1 The pile side resistance correction coefficient; s a The length of the periphery of the pile body is shown; q is the limit friction of the soil body around the pile; l is the pile length; beta is a 2 The resistance correction coefficient of the pile end is obtained; a. the p The area of the section of the pile body is shown; r is the ultimate bearing capacity of the pile end; p is a radical of s f is the ultimate bearing capacity of the natural foundation; k is a radical of 2 The correction coefficient is different between the actual bearing capacity of the soil foundation between piles and the limit bearing capacity of the natural foundation; lambda [ alpha ] 1 The ultimate strength exertion degree of the pile body is obtained; lambda [ alpha ] 2 The ultimate strength exertion degree of the soil between the piles is obtained; m is the replacement rate of the composite foundation; a is the number of cement filling layers; gamma ray c Is the gravity of the cement soil; a is the action area of the bottom surface of the foundation; h c The filling thickness of the cement soil layer; gamma is the soil gravity; h' i The thickness of the ith layer of the new filling layer; and Q is road traffic load.
The pile distance D of the pile body of the vertical pile body 11 positioned at the lower part of the edge of the road shoulder adopted by the invention is determined according to a pile distance calculation formula given in item 3 in building foundation treatment technical Specification 7.5.2:
in the formula, d is the diameter of a pile hole; rho dmax The maximum dry density of the pile soil;
the average dry density of the soil before foundation treatment;
the average compaction coefficient of the soil between piles after pore-forming and compaction is not less than 0.93.
The pile distance of the pile outside the edge of the road shoulder of the vertical pile body 11 adopted by the invention is calculated according to the following formula:
D n ＝D+nd/4
in the formula, D n The pile distance of the nth pile is obtained; d is the pile distance of the pile body at the lower part of the edge of the road shoulder; n is the nth pile outside the edge of the road shoulder; d is the pile diameter.
In the invention, the cement soil layer 4 is filled on the geogrid 3, and the filling thickness H of the cement soil layer 4 C The following formula requirements should be satisfied:
in the formula, the calculated depths of the old foundation and the pavement structure layer are both the height of the roadbed; dividing an old roadbed into m layers, wherein the number of cement soil filling layers at the lower part of a pavement structure layer is n, the soil body filled in a newly filled roadbed is n-1, and the soil body at the lower part of the old roadbed is divided into 2n-1 layers; i is any one of the layers; h c The filling thickness of the cement soil layer; e C Is the average compressive modulus of the cement soil layer;
the average additional stress of the cement soil layer is obtained;
and
the average compression modulus on the i-th layer soil of the old roadbed and the new filled soil body respectively; h' i The thickness of the ith layer of the new soil filling body; h i For the ith layer of old roadbedThe delamination thickness of (a).
The technical solution of the present invention is illustrated by a specific example below:
the highway subgrade widening structure is applied to the highway widening project from Tongwei to Darcy. The construction method of the highway subgrade widening structure applied to the loess area comprises the following specific steps:
1) construction preparation: the method comprises the steps of measuring and setting out, leveling the field and entering the equipment.
2) Step excavation: loosening soil and cleaning the side slope of the old roadbed 1, cleaning the bottom surface of a newly filled roadbed 5 and excavating steps of the old roadbed 1; the height of old roadbed excavation step 7 is 3m, and there is 2% inward sloping in the step.
3) Constructing a vertical pile body 11: the vertical pile body 11 is a miniature lime-soil pile, piles are piled at the widened bottom surface of the roadbed and is arranged in a quincunx shape; the pile distance D of the vertical pile body 11 is 3 times of the pile diameter.
4) And (3) construction of the geogrid: the geogrid 3 is laid along the old roadbed excavation step 7 and the groove 10 at the joint of the new roadbed and the old roadbed and is laid to the side slope of the new roadbed; the geogrid 3 is a bi-directional geogrid laid in double layers, the lap joint width of the geogrid is not less than 20cm, and the geogrid is anchored by U-shaped anchors and U-shaped fixing anchors; the geogrid 3 needs to adopt a product with high strength and ageing resistance; the laying gradient of the geogrid 3 is parallel to the road surface, the laying width is not less than 3m on a step part (an old road part), and the transverse total width is not less than 10 m; the transverse laying length of the geogrid 3 is not less than 4m, the embedded stable soil layer is not less than 1.5m, the laying stress is leveled, and the maximum particle size of the filler within 8cm from the geosynthetic material is not more than 60 mm.
5) And (4) constructing a cement soil layer: the cement soil layer 4 is filled on the geogrid 3, and sufficient compactness is guaranteed during filling.
6) And (5) constructing a newly filled roadbed: the newly filled roadbed 5 is filled on the cement soil layer 4 and is fully tamped in the filling process; the newly filled roadbed 5 is filled to the upper step surface and the groove 10; the top surface of the newly filled roadbed 5 is flush with the step surface and the groove surface at the joint.
7) Step 4), step 5), step 6) are circulating steps, and the circulating construction is carried out until the bottom surface of the cement soil layer 4 below the pavement structure layer 6 is reached.
8) And 6, constructing a pavement structure layer: and after measurement and paying off, manually leveling, backfilling with sand and stones, and finally constructing the concrete pavement in a construction mode. When the pavement is widened, the whole pavement structure layer of the old pavement is dug, after the widened part is filled, the whole pavement structure layer construction is carried out, and the finished pavement structure layer 10 is a whole. The pavement structure layer 10 includes a graded sand stone layer, a two-sand stone layer, and an asphalt concrete surface layer.
9) Construction of a drainage ditch 9: the drainage ditch 9 is preferably arranged 70cm outside the slope toe of the old roadbed 1 and the newly filled roadbed 5.
According to the invention, the filling amount of the newly filled soil body is reduced by a mode of paving the geogrid, the cement soil layer and the newly filled soil body for multiple times; the advantage of good compression resistance of the geogrid cement soil is utilized, differential settlement of the widened roadbed part is reduced, and meanwhile, the characteristic of small compression deformation of a cement soil layer is utilized to have a remarkable limiting effect on settlement of a newly filled roadbed; the newly filled roadbed is filled on the steps of the old roadbed in a layered mode, and the integrity and the stability of the new roadbed and the old roadbed are improved by utilizing the stability of soil bodies of the steps of the old roadbed; the geogrid, the cement soil layer and the original stable loess stratum which are newly filled at the bottom layer of the roadbed have the capability of controlling the settlement difference of the roadbed; the strength of the consolidated foundation under the old roadbed side slope is enhanced by the synergistic effect of the geogrid, the cement soil layer, the vertical pile bodies and the original stable loess stratum, the foundation bearing capacity of the foundation under the newly filled roadbed is improved, and the settlement generated by the newly filled roadbed is limited; the grooves at the joints of the new and old roadbeds enhance the splicing capacity of the joints of the new and old roadbeds through the synergistic effect of the geogrids and the cement soil layers, so that the overall connecting capacity of the new and old roadbeds is remarkably improved; the geogrid is laid on the steps of the newly filled roadbed, a cement soil layer is filled on the geogrid, and then the soil body of the newly filled roadbed is filled in a circulating filling mode, so that the consolidation strength of the steps of the old roadbed and the property of small compression deformation of the geogrid cement soil layer are fully utilized, the settlement of the newly filled roadbed is reduced, and the overall stability of the roadbed is also enhanced.
The invention mainly adopts a mode of adding a geogrid on a plurality of cement soil cushions to reduce the settlement of widened subgrades in loess areas, and the grooves are arranged at the joints of the old and new subgrades, so that the weak surfaces at the joints are strengthened, and the soil body of the lower foundation is strengthened by the vertical pile bodies. The settlement of the newly filled roadbed is limited, the loess foundation at the lower part of the newly filled roadbed is strengthened, and the splicing capacity at the joint is strengthened by the groove. The roadbed widening system comprises an old roadbed, a newly filled roadbed, a geogrid, a cement soil layer, a pavement structure layer and vertical piles; old roadbed slopes are excavated into step shapes, and grooves are excavated at the joints of new and old roadbeds; the vertical pile body is driven into the loess stratum; the geogrid is laid on the step surface of the old road abutment and the groove at the joint; filling cement soil on the geogrid; the newly filled roadbed is filled on the cement soil. The invention provides the highway subgrade widening structure, which can obviously reduce the settlement of new and old subgrades and has the advantages of high construction efficiency, small settlement deformation, low manufacturing cost, stable structure and good environmental protection.
The invention provides a roadbed widening structure suitable for a highway in a loess region and a construction method thereof, aiming at the defects of the existing roadbed widening technology and combining the characteristics of a roadbed in the loess region, and mainly aiming at the loess region, the settlement deformation of a soil body of a newly filled roadbed is effectively reduced through the synergistic effect of geogrid, cement soil and the newly filled soil body. The grooves arranged at the joints of the new and old roadbeds enhance the splicing capacity of the joints of the new and old roadbeds through the synergistic effect of the geogrids and the cement soil layers, so that the overall connecting capacity of the new and old roadbeds is remarkably improved; and meanwhile, the bearing capacity of the loess stratum at the lower part of the newly filled roadbed is enhanced by the synergistic effect of the vertical pile bodies and the loess stratum, and the settlement of the loess stratum at the lower part of the roadbed is also reduced. The invention has the advantages of small settlement deformation, stable structure and good integrity, and is suitable for highway subgrade widening engineering in loess areas in mountainous areas.
In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (7)
1. A highway subgrade widening structure is characterized in that the structure is arranged on the top surface of a loess stratum outside a slope on one side of an old subgrade;
the structure comprises a plurality of groups of first structural bodies, a group of second structural bodies, a pavement structural layer and a plurality of vertical pile bodies vertical to the loess stratum, wherein the first structural bodies, the second structural bodies and the pavement structural layer are sequentially arranged from bottom to top;
each group of first structure bodies comprises a geogrid, a cement soil layer and a newly filled roadbed which are sequentially arranged from bottom to top; each group of first structure bodies is close to the excavation surface of an old roadbed excavation step; the old roadbed excavation step is a step excavated from top to bottom on a side slope on one side of an old roadbed;
the second structure body comprises the geogrid and the cement soil layer which are sequentially arranged from bottom to top; the second structure body is close to the excavation surface of the old roadbed excavation step; the step surface of the old roadbed excavation step is provided with an inclined slope of 2% facing the center part of the step surface; the step surface is the horizontal surface of an old roadbed excavation step; the excavation surface is a vertical surface of an old roadbed excavation step;
the bottom surface of each cement soil layer is provided with a groove; the groove is close to the excavation surface of the old roadbed excavation step; the groove is a groove at the joint of the new roadbed and the old roadbed, a slope line of the old roadbed is positioned in the groove, and the width of the groove is 3 times of the pile diameter of the vertical pile body and 2 times of the pile distance of the vertical pile body; arranging a groove at the joint of the new roadbed and the old roadbed, and filling the groove with cement soil; the filling thickness of the cement soil in the groove at the joint is the same as the laying thickness of the cement soil at the step, and the filling width of the new and old roadbed part is not less than 1.5 m;
the cement soil layer is filled on the geogrid; the newly filled roadbed is filled between the upper cement soil layer and the lower cement soil layer and filled to the excavation step and the groove of the old roadbed; the newly filled roadbed is filled on the cement soil layer, and is fully tamped in the filling process; filling the newly filled roadbed to the upper step surface and the groove; the top surface of the newly filled roadbed is flush with the step surface and the groove surface at the joint; the cement soil layer and the newly filled roadbed are alternately filled; after the cement soil layer is filled, new filling roadbed filling is carried out, and the circular construction is carried out in sequence until the bottom surface of the cement soil layer filled at the lower part of the pavement structure layer;
the pile top of the vertical pile body is tightly attached to the bottom surface of the geogrid at the bottommost layer; the pile bottom of the vertical pile body is located inside the loess stratum.
2. The highway subgrade widening structure according to claim 1, further comprising a drainage ditch;
the escape canal sets up in the bottom loess stratum of 70cm department outside the geogrid the top surface.
3. The highway subgrade widening structure according to claim 1, wherein the geogrid is a double-layered bi-directional stretched plastic geogrid; the laying gradient of the geogrid is parallel to the road surface.
4. The highway subgrade widening structure according to claim 1, wherein the geogrids are fixed by U-shaped anchors.
5. The highway subgrade widening structure according to claim 1, wherein the vertical pile bodies are micro-lime-soil piles.
6. The highway subgrade widening structure according to claim 1, wherein a plurality of the vertical piles are arranged in a quincunx shape.
7. The highway subgrade widening structure according to claim 1, wherein the new roadbed is loess.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2013104877A (en) * | 2013-02-05 | 2014-08-10 | Николай Васильевич Меркушов | METHOD FOR EXPANDING THE ROAD DESIGN |
| CN104278608A (en) * | 2013-07-05 | 2015-01-14 | 杭州华水市政工程有限公司 | Novel highway embankment widened structure and construction method |
| CN208104936U (en) * | 2018-04-26 | 2018-11-16 | 马妮 | A kind of express highway roadbed widening structure |
| CN211571228U (en) * | 2019-12-28 | 2020-09-25 | 江苏财经职业技术学院 | Road surface roadbed mosaic structure for reconstruction and extension engineering |
| CN111827312A (en) * | 2020-07-28 | 2020-10-27 | 中国建筑第五工程局有限公司 | Slope reinforced retaining wall and construction method thereof |
-
2021
- 2021-08-27 CN CN202110993685.4A patent/CN113737593B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2013104877A (en) * | 2013-02-05 | 2014-08-10 | Николай Васильевич Меркушов | METHOD FOR EXPANDING THE ROAD DESIGN |
| CN104278608A (en) * | 2013-07-05 | 2015-01-14 | 杭州华水市政工程有限公司 | Novel highway embankment widened structure and construction method |
| CN208104936U (en) * | 2018-04-26 | 2018-11-16 | 马妮 | A kind of express highway roadbed widening structure |
| CN211571228U (en) * | 2019-12-28 | 2020-09-25 | 江苏财经职业技术学院 | Road surface roadbed mosaic structure for reconstruction and extension engineering |
| CN111827312A (en) * | 2020-07-28 | 2020-10-27 | 中国建筑第五工程局有限公司 | Slope reinforced retaining wall and construction method thereof |
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| CN113737593A (en) | 2021-12-03 |
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