A gradually changing geogrid applied to a widened roadbed

Abstract

The utility model discloses a kind of applied to the gradual change type geogrid of widening roadbed, including at least one layer geogrid layer, the geogrid layer includes first grid assembly and second grid assembly: first grid assembly includes multiple hexagonal geogrid, multiple The hexagonal geogrid is laid flat, and the first grid assembly is located in new roadbed middle part;Second grid assembly has two groups, two groups The second grid assembly is respectively set in the left and right sides of the first grid assembly along the width direction of road, and the second grid assembly in inside is located at the junction of new and old roadbed, the second grid assembly in outside is located at new roadbed outside, The second grid assembly includes multiple triangular geogrid, multiple The triangular geogrid is laid flat.This gradual change type geogrid can solve the problem of insufficient strength of geogrid, uneven deformation of soft soil roadbed and stress concentration of widening roadbed.

Description

Technical Field

[0001] This utility model relates to the field of soft soil subgrade treatment for road reconstruction and expansion, and in particular to a gradient geogrid used for widening subgrades. Background Technology

[0002] As the demand for highway reconstruction and expansion in my country increases, so too does the number of problems encountered. One of the main issues is that the presence of soft soil subgrades can lead to uneven deformation between the old and new subgrades if not properly treated, resulting in road surface cracking, bridge approach slab settlement, and other problems.

[0003] To improve the coordination of deformation between new and old roadbeds, it is common practice to treat the roadbed after widening the road surface. This includes the installation of geogrids to improve the integrity of the roadbed, resist horizontal displacement, reduce settlement, and increase bearing capacity.

[0004] Studies have found that when laying geogrids in widening roadbeds, a single rectangular geogrid is often used. However, when faced with uneven stress distribution in soft soil roadbeds and insufficient strength of rectangular geogrids, problems arise over time, such as uneven settlement, lateral extrusion of the roadbed, and local shear deformation cracking. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide a gradient geogrid for widening roadbed, which solves the problems of insufficient strength of geogrid, uneven deformation of soft soil roadbed and stress concentration in widened roadbed.

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution: a gradient geogrid for widening roadbeds, comprising at least one geogrid layer, wherein the geogrid layer comprises:

[0007] The first geogrid assembly includes multiple hexagonal geogrids, which are laid flat and located in the middle of the new roadbed.

[0008] The second grid assembly consists of two sets, which are respectively arranged on the left and right sides of the first grid assembly along the width direction of the road surface. The second grid assembly located on the inner side is at the junction of the old and new roadbeds, while the second grid assembly located on the outer side is on the outer side of the new roadbed. The second grid assembly includes multiple triangular geogrids, which are laid flat.

[0009] Furthermore, the geogrid layer has three layers.

[0010] Furthermore, when the geogrid layer is multi-layered, the lower geogrid layer is positioned relative to the upper geogrid layer on the outer side of the roadbed.

[0011] Furthermore, the hexagonal geogrid in the first geogrid assembly is disposed adjacent to each other.

[0012] Furthermore, the hexagonal geogrid is a regular hexagon.

[0013] Furthermore, the triangular geogrids in the second geogrid assembly are arranged adjacent to each other, and every six triangular geogrids are spliced ​​together to form a hexagon.

[0014] Furthermore, the triangular geogrid is an equilateral triangle.

[0015] The beneficial effects of this utility model are:

[0016] The aforementioned gradient geogrid, used for widening roadbeds, involves laying a second geogrid assembly at the junction of the old and new roadbeds during construction, followed by laying a first geogrid assembly in the middle of the new roadbed, and then laying a second geogrid assembly on the outer side of the new roadbed.

[0017] This type of gradient geogrid is used for roadbed reconstruction and expansion. Since the high-stress areas of the reconstructed roadbed are mainly concentrated at the joints and on the outer side of the new roadbed, triangular geogrids are placed at the joints and on the outer side of the new roadbed, while hexagonal geogrids are placed in the remaining middle section. This flexible geogrid placement effectively solves problems such as uneven settlement of soft soil roadbeds and improves the overall integrity of the soft soil roadbed during reconstruction and expansion. Compared to other single placement methods, this method can maximize the bearing capacity and deformation resistance of the soft soil roadbed. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of this utility model, the accompanying drawings used in the specific embodiments will be briefly described below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0019] Figure 1 A schematic diagram of a gradient geogrid applied to widening a roadbed, provided as an embodiment of the present invention;

[0020] Figure 2 for Figure 1 The diagram shown illustrates the application of gradient geogrids in roadbed widening.

[0021] Figure 3 and Figure 4 Diagrams showing the dispersion of normal forces on triangular and rectangular geogrids, respectively;

[0022] Figure 5 and Figure 6 This diagram illustrates the dispersion of tensile forces on triangular and rectangular geogrids.

[0023] Figure 7 A schematic diagram comparing the internal spaces of triangular and rectangular geogrids;

[0024] Figure 8 A comparative schematic diagram of the internal space of a hexagonal geogrid and a rectangular geogrid, which are composed of triangular geogrids.

[0025] Figure 9 The embedding effect of soil particles in two types of geogrids: a hollow hexagonal geogrid and a hexagonal geogrid composed of triangular geogrids.

[0026] Figure 10 This is a schematic diagram of the loads acting on the roadbed.

[0027] Figure 11 This describes the stress and strain condition of the geogrid.

[0028] Figure 12 This is a schematic diagram showing the distribution of measurement rings in a multi-layer geogrid.

[0029] Figure 13 A schematic diagram of the porosity at the junction of the roadbed;

[0030] Figure 14 A schematic diagram of the porosity in the middle of the new roadbed;

[0031] Figure 15 A schematic diagram of the porosity on the outer side of the new roadbed;

[0032] Figure 16 This shows the longitudinal layout of the gradient geogrid.

[0033] Figure label:

[0034] 100, First grille assembly; 200, Second grille assembly. Detailed Implementation

[0035] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention; therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] Please see Figures 1 to 2This utility model provides a gradient geogrid for widening roadbeds, comprising at least one geogrid layer, the geogrid layer comprising a first geogrid assembly 100 and a second geogrid assembly 200.

[0037] Specifically, the first geogrid assembly 100 includes multiple hexagonal geogrids, which are laid flat and located in the middle of the new roadbed. There are two sets of second geogrid assemblies 200, each set positioned along the width of the road surface on the left and right sides of the first geogrid assembly 100. The inner second geogrid assembly 200 is located at the junction of the old and new roadbeds, while the outer second geogrid assembly 200 is located on the outer side of the new roadbed. Each second geogrid assembly 200 includes multiple triangular geogrids laid flat.

[0038] During construction, the second grid assembly 200 is first laid at the junction of the new and old roadbeds, then the first grid assembly 100 is laid in the middle of the new roadbed, and then the second grid assembly 200 is laid on the outside of the new roadbed.

[0039] Triangular geogrids, with their denser mesh distribution and triangular stability, are suitable for high-stress areas. Hexagonal geogrids, on the other hand, offer higher frictional resistance due to their hexagonal openings, preventing lateral movement of soil within the pores and thus improving resistance to lateral deformation of the subgrade. They are suitable for uneven settlement in soft soil subgrades.

[0040] This type of gradient geogrid is used for roadbed reconstruction and expansion. Since the high-stress areas of the reconstructed roadbed are mainly concentrated at the joints and on the outer side of the new roadbed, triangular geogrids are placed at the joints and on the outer side of the new roadbed, while hexagonal geogrids are placed in the remaining middle section. This flexible geogrid placement effectively solves problems such as uneven settlement of soft soil roadbeds and improves the overall integrity of the soft soil roadbed during reconstruction and expansion. Compared to other single placement methods, this method can maximize the bearing capacity and deformation resistance of the soft soil roadbed.

[0041] In practical implementation, when the geogrid layer is multi-layered, the lower geogrid layer is positioned towards the outer side of the subgrade relative to the upper geogrid layer. This method creates staggered, multi-layered tensile barriers in the thickness direction of the subgrade, further improving the bearing capacity and deformation resistance of the soft soil subgrade. In practice, the geogrid layer can be configured as three layers: upper, middle, and lower.

[0042] Furthermore, to increase the frictional resistance of the first geogrid assembly 100, the hexagonal geogrids in the first geogrid assembly 100 can be arranged adjacent to each other, thereby increasing the number of hexagonal geogrids and further increasing the frictional resistance, which in turn further enhances the ability to resist uneven deformation of the roadbed. Moreover, the hexagonal geogrids are preferably regular hexagons.

[0043] Similarly, to further improve the deformation resistance of the second geogrid assembly 200, the triangular geogrids in the second geogrid assembly 200 can be arranged adjacent to each other, and every six triangular geogrids can be spliced ​​together to form a hexagon. The number of triangular geogrids can also be increased to improve its deformation resistance. Furthermore, the triangular geogrids are preferably regular hexagons.

[0044] The following sections provide a detailed analysis and comparison of triangular and hexagonal geogrids relative to traditional rectangular geogrids:

[0045] First, let's analyze the distribution of force:

[0046] According to the formula:

[0047]

[0048] Specifically: F3 is the horizontal tensile force generated by the geogrid along the outer side of the roadbed; F4 is the pull-out resistance generated by the triangular geogrid along the rib direction; F5 and F4 are the same forces, both being pull-out resistance generated along the rib direction; F6 and F7 are both pull-out resistance generated by the rectangular geogrid along the rib direction.

[0049] Please refer to Figure 3 and Figure 4 It can be seen that when triangular geogrids and rectangular geogrids are subjected to normal pressure, the triangular geogrid distributes the force evenly and in multiple directions, while the rectangular geogrid distributes the force evenly in both longitudinal and transverse directions and is prone to stress concentration at the four corners. Therefore, when subjected to uneven stress, the triangular geogrid has a better force distribution effect than the rectangular geogrid.

[0050] Please also refer to Figure 5 and Figure 6 It can be seen that when triangular geogrids and rectangular geogrids are subjected to the same tensile force, triangular geogrids generate greater pull-out resistance and are more able to firmly hold the reinforcement and soil at stress concentration points.

[0051] Pull-out tests were conducted on rectangular and triangular geogrids using the same physical and mechanical properties. The results showed that when a normal pressure of 30 kPa was applied, the pull-out resistance of the triangular geogrid exceeded 15 kN / m, while that of the rectangular geogrid was less than 15 kN / m. Furthermore, due to the stability of triangles, the triangular geogrid was less prone to deformation than the rectangular geogrid under the same pressure. In addition, the strength of the geogrid is also related to the number of ribs; more ribs result in better structural stability. Since triangular geogrids can be assembled into hexagons, the triangular geogrid exhibits the best stability, followed by the hexagonal geogrid, with the rectangular geogrid being the least stable. The triangular geogrid generates greater pull-out resistance and is more effective at securing the reinforcement and soil at stress concentration points.

[0052] Therefore, it can be concluded that triangular geogrids are more advantageous for the junction of old and new subgrades with shear stress concentration and for the outer side of the new subgrade.

[0053] Secondly: Analysis of the stabilizing effect on the upper and lower layers of filler particles:

[0054] Studies on geogrids show that smaller rib spacing results in better interlocking between the reinforcement and the soil. Smaller spacing means a smaller geogrid space; with this smaller space, soil particles move more vigorously within the geogrid, leading to more compacted fill under stress and reduced soil porosity. Using rectangular and hexagonal geogrids with the same rib spacing, from... Figure 7 and Figure 8 It can be seen that, at the same spacing, rectangular geogrids have a larger spatial volume than hexagonal geogrids. Soil particles travel a longer distance within a rectangular geogrid, resulting in greater movement of the fill material. The maximum movement occurs at the corners of the rectangle, where stress concentration is more likely, making the geogrid more vulnerable and prone to failure when soil particles reach these corners. In contrast, hexagonal geogrids, with the same small spacing, can achieve a smaller area. The movement distance of soil particles is reduced, and stress concentration is less likely at the corners. Soil particles are better embedded within the hexagonal geogrid, resulting in better reinforcement performance.

[0055] Therefore, it can be concluded that using a hexagonal geogrid structure in the middle of the new roadbed is more stable than using a rectangular geogrid and is more conducive to resisting uneven settlement of soft soil roadbed.

[0056] Furthermore, based on the particle composition of the subgrade soil (see Table 1), it can be seen that larger-diameter gravel and smaller-diameter sand constitute the largest proportion of the subgrade soil, while the other components account for a very small percentage. Based on the parameters of particle size, content, and porosity, a simple layout of the soil particle distribution was constructed. Combined with triangular and hexagonal geogrids, the embedding effect of soil particles in the two types of geogrids can be visually observed (e.g., ...). Figure 9 ).

[0057] Table 1

[0058]

[0059] Because the size and distribution of soil particles are random, soil particles cannot completely fit into the geogrid during installation. In cases with large-diameter soil and rocks and high porosity, the triangular spaces are small, and the ribs are numerous, resulting in more soil and rocks failing to fully enter the geogrid. In contrast, hexagonal geogrids have no ribs dividing their internal space, offering greater capacity for large-diameter particles and high porosity. Therefore, hexagonal geogrids are more effective at embedding larger-diameter, more porous soil layers.

[0060] Therefore, based on the analysis of force distribution and the stabilization effect of the upper and lower layers of filler particles, it can be concluded that the application effect of triangular and hexagonal gradient combination geogrids is better than that of single rectangular geogrids in the reconstruction and expansion of roadbeds.

[0061] Third: Analyze the loads on the road surface:

[0062] Since the double-sided roadbed reconstruction and expansion is a symmetrical model, only half of the reconstruction and expansion roadbed needs to be analyzed. For the loads on the pavement, please refer to [link to relevant documentation]. Figure 10 .

[0063] The stress state of a rectangular geogrid is analyzed, considering both uniformly distributed loads with similar vehicle weights in the four lanes and abrupt loads where a heavier vehicle travels along the side, causing the fourth lane to bear a significantly greater weight than the other three lanes.

[0064] Please refer to the stress-strain condition of the geogrid. Figure 11 It is evident that under normal vehicle traffic conditions, the road surface load distribution is relatively uniform, with the geogrid experiencing the greatest tensile force at the junction of the old and new roadbeds. However, considering that heavy vehicles traveling along the side increase the pressure on the upper part of the fourth lane, leading to increased soil compression in all directions, the tensile force on the geogrid on the outer side of the roadbed also increases. Therefore, to ensure the normal use of the roadbed, a higher-strength triangular geogrid should be installed at the edge of the outermost lane of the new roadbed.

[0065] Fourth: Analysis based on porosity:

[0066] exist Figure 12 Twelve measuring circles, each 0.4m in diameter, were set up in the middle, and their positions are as follows: Figure 1 As shown, the porosity variation law in the measurement circle is analyzed.

[0067]

[0068] Wherein, n circles represent the porosity in the measurement circle, S holes represent the pore area of ​​the measurement circle, and S circles represent the area of ​​the measurement circle. The porosity variation in the measurement circle was studied and analyzed using the discrete-continuous coupling analysis method.

[0069] Please see Figures 13 to 14 As shown in the figure, the porosity of the old subgrade soil at the junction is smaller than that of the new subgrade soil, and the difference in soil porosity between the old and new soils is large. This means that the soil particles between the old and new soils are not uniformly dense, which will lead to uneven settlement in the later stage. This will cause the laid geogrid to be easily pulled up and down at the corner, causing damage. Therefore, a stronger triangular geogrid is needed at the junction.

[0070] Compared to other areas, the porosity change on the outer side of the new roadbed is the smallest, indicating that the movement of soil particles is small here, and the requirement for soil particle embedding is lower. However, stress concentration is prone to occur at the toe of the slope, and due to the presence of heavy vehicles traveling alongside, the load pressure on the outer side of the newly built road is greater, and the stress on the geogrid is prone to sudden changes. Therefore, a higher-strength triangular geogrid is used.

[0071] The porosity differs significantly between the first and second rows of geogrids in the middle of the new roadbed, but the porosity variation between the two layers is relatively stable. The porosity of the second row of geogrids in the upper middle layer is generally higher than in other locations, indicating that the soil particles are more dispersed. Using hexagonal geogrids with larger spaces can more effectively embed the soil particles. The first row of geogrids in the lower middle layer has lower porosity due to better soil compaction. However, considering the lower stress experienced by the geogrids in the middle, using hexagonal geogrids with moderate strength is more economical than using triangular geogrids.

[0072] This further proves that the horizontal layout of the gradient geogrid is as follows: triangular geogrids are used at the junctions, hexagonal geogrids are used in the middle of the new roadbed, and finally triangular geogrids are used from the inner edge of the outermost lane of the roadbed to the outer side of the slope.

[0073] Furthermore, a longitudinal analysis is conducted:

[0074] The longitudinal layout of the gradient geogrid can be analyzed based on previous studies of rectangular geogrids. The distribution of rectangular geogrids can be seen... Figure 14 ,

[0075] Table 2 shows the statistical results of the grid placement effect based on the number of steps commonly used in engineering practice.

[0076] Table 2

[0077]

[0078] The survey shows that more layers of geogrid in the roadbed are not necessarily better. After three layers, the effect of the geogrid in reducing horizontal displacement becomes less significant, and the change in vertical displacement also gradually decreases. Therefore, the longitudinal layout of the gradient geogrid should be rationally selected based on experience with rectangular geogrid installation and the actual engineering conditions.

[0079] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. A gradient geogrid for widening roadbeds, characterized in that, It includes at least one geogrid layer, the geogrid layer comprising: The first geogrid assembly includes multiple hexagonal geogrids, which are laid flat and located in the middle of the new roadbed. The second grid assembly consists of two sets, which are respectively arranged on the left and right sides of the first grid assembly along the width direction of the road surface. The second grid assembly located on the inner side is at the junction of the old and new roadbeds, while the second grid assembly located on the outer side is on the outer side of the new roadbed. The second grid assembly includes multiple triangular geogrids, which are laid flat.

2. The gradient geogrid for widening roadbeds according to claim 1, characterized in that, The geogrid layer has three layers.

3. The gradient geogrid for widening roadbeds according to claim 2, characterized in that, When the geogrid layer is multi-layered, the lower geogrid layer is positioned towards the outer side of the roadbed relative to the upper geogrid layer.

4. The gradient geogrid for widening roadbeds according to claim 1, characterized in that, The hexagonal geogrid in the first geogrid assembly is arranged adjacent to each other.

5. The gradient geogrid for widening roadbeds according to claim 1 or 4, characterized in that, The hexagonal geogrid is a regular hexagon.

6. The gradient geogrid for widening roadbeds according to claim 1, characterized in that, The triangular geogrids in the second geogrid assembly are arranged adjacent to each other, and every six triangular geogrids are spliced ​​together to form a hexagon.

7. The gradient geogrid for widening roadbeds according to claim 1 or 6, characterized in that, The triangular geogrid is an equilateral triangle.

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