Lightweight widened embankment structure for bridgehead transition section of soft soil roadbed

Abstract

The utility model relates to a light widening embankment structure for a bridgehead transition section of a soft soil roadbed. The light widening embankment structure is divided into three stepped transition sections in the longitudinal direction, namely a normal transition section behind a bridge abutment, a first stepped transition section and a second stepped transition section, in the depth direction, the bottom is an in-situ curing layer obtained by treating the soft soil layer through an in-situ curing technology; a broken stone hardcore is directly filled above the in-situ curing layer of the normal transition section behind the bridge abutment, earth-rock roadbed layers are filled above the in-situ curing layers of the first step section transition section and the second step section transition section in a layered manner, and the broken stone hardcore is filled above the earth-rock roadbed layers; composite geotechnical cloth is laid on the broken stone hardcore, and a foam concrete layer is arranged on the composite geotechnical cloth; the top layers of the foam concrete layers of the three stepped transition sections are flush. According to the scheme, the settlement rate of the soft foundation under the load effect can be reduced, the additional stress of the roadbed on the foundation is reduced, and therefore the stability and durability of the structure are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to roadbed splicing construction technical field especially relates to a soft soil roadbed bridge head transition section light splicing embankment structure. BACKGROUND

[0002] With the growth of traffic volume and the promotion of social demand, the early built highway is difficult to meet the demand of current traffic flow, and it is urgent to expand the traffic capacity of the road. Because the newly built road will not only occupy a large amount of land, but also significantly increase the investment cost. Therefore, the reconstruction and expansion (the method of widening on one side or both sides) of the existing road is beneficial to reduce the land occupation and save the funds.

[0003] In the road built in China, many road sections are located on deep soft soil foundation. Compared with ordinary roadbed, soft soil foundation has the characteristics of low strength, long consolidation time and easy deformation. After years of operation, the overall settlement of the roadbed tends to be stable. For soft soil foundation road, especially the bridge head section, the new and old roadbeds are prone to excessive deformation or uneven settlement in longitudinal and transverse directions. At present, the treatment effect of most roadbed widening projects is limited, and it is difficult to effectively control the differential settlement of new and old roadbeds. Especially in the road-bridge transition section, uneven settlement is easy to cause the bridge head bumping phenomenon, and even may cause the secondary bumping problem, which seriously affects the traffic quality and driving safety of the reconstruction and expansion road. SUMMARY

[0004] In order to solve the above problems, the purpose of the utility model is to provide a soft soil roadbed bridge head transition section light splicing embankment structure.

[0005] The soft soil roadbed bridge head transition section light splicing embankment structure is divided into three stepped transition sections in longitudinal direction: normal transition section behind abutment, first stepped section transition section and second stepped section transition section, and slope steps with a slope ratio of 1:1.5 are arranged between the normal transition section behind abutment and the first stepped transition section and between the first stepped section and the second stepped transition section.

[0006] In the depth direction, the bottom is the in-situ solidification layer obtained by treating the soft soil layer by in-situ solidification technology; the in-situ solidification layer of the normal transition section behind abutment is directly filled with gravel cushion layer above, the in-situ solidification layers of the first stepped section transition section and the second stepped section transition section are layered filled with earthwork and stone embankment layer above, and the earthwork and stone embankment layer is filled with gravel cushion layer above; the composite geotextile is laid on the gravel cushion layer, and the foam concrete layer is arranged above the composite geotextile; the top layers of the foam concrete layers of the three stepped transition sections are flush and arranged with reinforced concrete layer; the pavement is laid on the reinforced concrete layer.

[0007] Preferably, the height of the slope step between the normal transition section behind abutment and the first stepped transition section and between the first stepped section and the second stepped transition section is 0.5m.

[0008] Preferably, the length of the normal transition section behind the abutment is greater than the lengths of the first and second stepped transition sections, and the lengths of the first and second stepped transition sections are the same.

[0009] Preferably, the height of the in-situ solidification layer is 1.0-1.5m.

[0010] Preferably, the height of the crushed stone cushion is 0.3m.

[0011] Preferably, the height of the earthwork subgrade of the first stepped transition section is 0.5m, and the height of the earthwork subgrade of the second stepped transition section is 1.0m.

[0012] Preferably, the foam concrete layer is provided with settlement joints at intervals of 5-15m.

[0013] Preferably, steel wire meshes are arranged at a distance of 0.5m from the top and bottom layers in the foam concrete layer.

[0014] Preferably, a 3cm-thick polystyrene board is arranged as a buffer layer between the abutment back and the fill.

[0015] Preferably, cantilevered reinforced concrete retaining walls are arranged on the two outer sides of the widened roadbed.

[0016] The above scheme adopts a thickness stepped transition design combining in-situ solidification technology with foam concrete, utilizes the characteristics of light self-weight and small additional load of foam concrete on the foundation, effectively reduces the additional stress of the roadbed on the foundation, and thus improves the stability and durability of the structure. Meanwhile, the stepped structure helps to gradually transition the fill load, slows down the settlement rate of the soft foundation under the load, and effectively reduces the overall settlement and uneven settlement phenomenon. This design effectively improves the connection between the new and old roadbeds, avoids the bridgehead bumping problem caused by settlement differences, and ensures the flatness of the road surface and the driving comfort. Meanwhile, the use of lightweight materials facilitates transportation, has low construction difficulty, is suitable for rapid construction of the bridgehead widened section, and helps to further shorten the engineering period. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a longitudinal section schematic diagram of the embankment of the present application;

[0018] Figure 2 is a transverse section schematic diagram of the embankment of the present application.

[0019] REFERENCE SIGNS:

[0020] 1. Normal transition section behind the abutment, 2. Transition section of the first step section, 3. Transition section of the second step section, 4. Height of the foam concrete layer of the normal transition section behind the abutment, 5. Height of the foam concrete layer of the transition section of the first step section, 6. Height of the foam concrete layer of the transition section of the second step section, 7. In-situ solidification layer, 8. Gravel cushion layer, 9. Earth and stone road base, 10. Composite geotextile, 11. Foam concrete layer, 12. Wire mesh, 13. Settlement joint, 14. Reinforced concrete layer, 15. Pavement, 16. Polystyrene board, 17. Reinforced concrete retaining wall, 18. Old roadbed, 19. Widened roadbed, 20. Slope line of old roadbed, 21. Excavation steps. DETAILED DESCRIPTION

[0021] The embodiments of the present utility model are described in detail below.

[0022] This embodiment provides a light-weight widened embankment structure for a soft soil roadbed bridgehead transition section. Figure 1 As shown, it is divided into three stepped transition sections in the longitudinal direction: the normal transition section 1 behind the abutment, the first step transition section 2, and the second step transition section 3. A slope with a slope ratio of 1:1.5 is set between the normal transition section at the bridge head and the first step transition section, and between the first step transition section and the second step transition section. The slope step height is 0.5m. Among them, the length of the normal transition section 1 behind the abutment is greater than the length of the first step transition section 2 and the second step transition section 3, and the lengths of the first step transition section 2 and the second step transition section 3 are the same. In one embodiment, the total length of the three stepped transition sections is 50 meters, with the normal transition section 1 behind the abutment being 20 meters long, and the first step transition section 2 and the second step transition section 3 being 15 meters long respectively. The stepped structure helps to gradually transition the fill load, slow down the settlement rate of the soft foundation under load, and effectively reduce overall settlement and uneven settlement. This design effectively improves the connection between the new and old roadbeds, avoids the problem of vehicle jumping at the bridge head caused by settlement differences, and ensures the smoothness and driving comfort of the road surface.

[0023] In the depth direction, the bottom is the in-situ solidification layer 7 obtained by treating the soft soil layer by in-situ solidification technology. The bottom soft soil layer is treated by in-situ solidification technology, and the treatment depth is 1.0-1.5 m. The broken stone cushion layer 8 is directly filled above the in-situ solidification layer 7 of the normal transition section 1 behind the abutment in this embodiment. The height of the filled broken stone cushion layer 8 in this embodiment is 0.3 m. The earthwork roadbed layer 9 is layered and filled above the in-situ solidification layer 7 of the first stepped transition section 2 and the second stepped transition section 3; in this embodiment, the filling height of the earthwork roadbed layer 9 of the first stepped transition section 2 is 0.5 m, which is filled in two layers, and the joint with the normal transition section 1 behind the abutment is provided with a 1:1.5 slope connection; the layered filling height of the earthwork roadbed of the second stepped transition section 3 is 1.0 m, and the joint with the first stepped transition section 2 is provided with a 1:1.5 slope connection. The broken stone cushion layer 8 is filled above the earthwork roadbed layer 9 of the first stepped transition section 2 and the second stepped transition section 3; in this embodiment, the in-situ solidification layer 7 at the joint of the steps is also sequentially filled with the earthwork roadbed layer and the broken stone cushion layer, and the heights of the broken stone cushion layers are consistent. The composite geotextile 10 is laid above the broken stone cushion layer 8. The foam concrete layer 11 is provided above the composite geotextile 10, and the height of the foam concrete layer of the normal transition section behind the abutment, the height of the foam concrete layer of the first stepped transition section, and the height of the foam concrete layer of the second stepped transition section are respectively shown in Figure 1 , the top of the foam concrete layer 11 of the three stepped transition sections is flush after the foam concrete layer 11 is filled. In the preferred embodiment, steel wire meshes 12 are respectively provided at a distance of 0.5 m from the top and bottom layers in the foam concrete layer 11 to enhance the tensile strength of the structure, and the steel wire meshes 12 in this embodiment are steel wire meshes with a mesh size of 5 cm x 5 cm. Preferably, settlement joints 13 are provided in the foam concrete layer 11 at intervals of 5-15 m to cope with the temperature shrinkage and uneven settlement deformation of the foam concrete roadbed. The reinforced concrete layer 14 is provided on the top of the foam concrete layer 11, the reinforced concrete layer 14 in this embodiment is 20 cm thick, and the pavement 15 is laid on the reinforced concrete layer 14. In this embodiment, a 3 cm thick polystyrene board 16 is provided as a buffer layer between the abutment back and the fill to further reduce the settlement difference at the joint of the new and old structures and prevent the bridgehead bumping phenomenon.

[0024] In the lateral direction, the widened roadbed 19 is provided outside the old roadbed 18, as shown in Figure 2 , the cantilever reinforced concrete retaining wall 17 is provided outside the widened roadbed 19 to serve as a side form for the foam concrete filling and to slope the roadbed. In construction, there is an excavation step 21 along the slope line 20 of the old roadbed, and the step width is not less than 1 m and the horizontal slope is inclined inward by 4%. The lateral widened roadbed of the transition section is filled by conventional technology, which is not described here.

[0025] Although the embodiments of the utility model have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the utility model, and the scope of the utility model is defined by the claims and their equivalents.

Claims

1. A light-weight widened embankment structure for soft soil subgrade bridgehead transition section, characterized in that, three stepped transition sections are divided in the longitudinal direction: a normal transition section behind the abutment, a first stepped transition section, and a second stepped transition section, and slope steps with a slope ratio of 1:1.5 are provided between the normal transition section and the first stepped transition section, and between the first stepped transition section and the second stepped transition section; in the depth direction, the bottom is an in-situ solidification layer obtained by treating the soft soil layer with in-situ solidification technology; a crushed stone cushion layer is directly filled above the in-situ solidification layer of the normal transition section behind the abutment, and a soil-rock embankment layer is layered filled above the in-situ solidification layer of the first stepped transition section and the second stepped transition section, and a crushed stone cushion layer is filled above the soil-rock embankment layer; a composite geotextile is laid above the crushed stone cushion layer, and a foam concrete layer is provided above the composite geotextile; the top layers of the foam concrete layers of the three stepped transition sections are flush and a reinforced concrete layer is provided; a pavement is laid on the reinforced concrete layer.

2. The light-weight widened embankment structure of soft soil subgrade bridge head transition section according to claim 1, characterized in that, The height of the slope steps between the normal transition section and the first stepped transition section, and between the first stepped transition section and the second stepped transition section is 0.5 m.

3. The light-weight widened embankment structure of soft soil subgrade bridge head transition section according to claim 1, characterized in that, The length of the normal transition section behind the abutment is greater than that of the first stepped transition section and the second stepped transition section, and the lengths of the first stepped transition section and the second stepped transition section are the same.

4. The light-weight widened embankment structure of soft soil subgrade bridge head transition section according to claim 1, characterized in that, The height of the in-situ solidification layer is 1.0-1.5 m.

5. The light-weight widened embankment structure of soft soil subgrade bridge head transition section according to claim 1, characterized in that, The filling height of the crushed stone cushion layer is 0.3 m.

6. The light-weight widened embankment structure of soft soil subgrade bridge head transition section according to claim 1, characterized in that, The layered filling height of the soil-rock embankment of the first stepped transition section is 0.5 m, and the layered filling height of the soil-rock embankment of the second stepped transition section is 1.0 m.

7. The light-weight widened embankment structure of soft soil subgrade bridge head transition section according to claim 1, characterized in that, The foam concrete layer is provided with settlement joints at intervals of 5-15 m.

8. The soft soil subgrade lightweight widened embankment structure at bridge end transition section of claim 1, wherein, Steel wire meshes are provided at a distance of 0.5 m from the top and bottom layers in the foam concrete layer.

9. The light weight widened embankment structure of soft soil subgrade abutment transition section according to claim 1, characterized in that, A 3 cm thick polystyrene board is provided as a buffer layer between the abutment back and the fill.

10. The light-weight widened embankment structure of soft soil subgrade bridge head transition section according to claim 1, characterized in that, Cantilever reinforced concrete retaining walls are provided on both outer sides of the widened embankment.

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