An emergency road layout structure and construction method suitable for suspended monorails

Abstract

This invention discloses an emergency road layout structure and its construction method suitable for suspended monorails, belonging to the field of suspended monorail construction technology. By setting up a first, second, and third roadbed, the construction of a temporary access road, vegetation strip, and emergency road structure are completed sequentially, improving the functionality of the emergency road structure, enabling multiple lanes to be combined, and simplifying the construction process of the suspended monorail emergency road layout structure. The construction method for the emergency road layout structure of the suspended monorail in this invention is simple in steps and convenient in construction. It can effectively meet the construction requirements of the emergency road layout structure on one side of the suspended monorail line, and meet the initial construction requirements of the temporary access road during the emergency road construction process. It eliminates the need for additional roadbed structures, reduces repeated construction and excessive demolition of the construction road structure, saves material and labor costs, improves the construction efficiency of the emergency road layout structure, and meets the requirements of economy and practicality.

Description

Technical Field

[0001] This invention belongs to the field of suspended monorail construction technology, specifically relating to an emergency road layout structure and construction method suitable for suspended monorails. Background Technology

[0002] In recent years, with the rapid development of urban rail transit, various rail transit systems have been built one after another, such as suspended monorail, straddle-type monorail, and medium-low speed maglev, which have been increasingly used. Among them, suspended monorail has gradually been widely used in China due to its advantages such as good sightseeing effect, low cost, and short construction period.

[0003] In actual construction, because suspended monorails mainly adopt a special system of elevated laying and vehicles located below the track beams, the design and construction of supporting ground rescue emergency roads must be given special consideration, which puts forward higher requirements for the integrated design of emergency road layout structures. In addition, in actual construction, it is also necessary to fully consider various needs such as construction access roads, leisure greenways, access for rescue vehicles when trains break down, and maintenance of facilities and equipment during operation.

[0004] Therefore, suspended monorails often require various types of roads along their routes, including construction access roads, park greenways, rescue channels, and maintenance roads. This differs significantly from conventional rail transit systems, making existing construction methods ineffective in meeting actual construction needs. Furthermore, the existing emergency road layout for suspended monorails often involves multiple intersecting roads on both sides of the line, with some roads even running parallel and sharing passageways, resulting in road redundancy, increased construction costs, and wasted resources. Summary of the Invention

[0005] In view of one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides an emergency road layout structure and construction method suitable for suspended monorails, which can realize the accurate construction of the emergency road layout structure for suspended monorails and meet the use needs of emergency roads in the actual operation of suspended monorails.

[0006] To achieve the above objectives, one aspect of the present invention provides a construction method for an emergency road layout structure suitable for suspended monorails, comprising the following steps:

[0007] (1) Determine the construction location of the emergency road layout structure and level it into a construction site for construction;

[0008] (2) Construct the first roadbed and the second roadbed on the construction site; wherein the first roadbed and the second roadbed are arranged sequentially along the transverse direction of the suspended monorail, and the first roadbed is located on the side of the second roadbed away from the suspended monorail line.

[0009] (3) Apply a certain thickness of cement mortar to the first and second roadbeds to form a construction access road on the top of the two roadbeds;

[0010] (4) Using the construction access road, the construction of the suspended monorail line is carried out along the longitudinal direction of the suspended monorail transit.

[0011] (5) Remove the mortar layer on the first and second roadbeds and restore the soil layer on top of the two roadbeds;

[0012] (6) A green area is constructed above the first roadbed, and a vegetation belt is formed on the side of the second roadbed away from the suspended monorail line;

[0013] (7) A third roadbed with a compaction standard that meets the requirements for emergency road use shall be constructed on top of the second roadbed;

[0014] (8) On the third roadbed, the subbase, base and surface layers are laid from bottom to top to form an emergency road structure.

[0015] As a further improvement of the present invention, the construction location is an embankment section; in process (2), the construction of the two roadbeds is as follows:

[0016] After leveling the site, the topsoil of the original ground is removed. Then, the soil condition is tested to determine whether the compaction and strength of the underlying layer after compaction can meet the strength index requirements of the roadbed. If it meets the requirements, the roadbed is directly filled and backfilled. If it does not meet the requirements, the soil layer is excavated to the bottom line of the roadbed. Then, the ground is compacted and backfilled after compaction. Finally, the first roadbed and the second roadbed are formed.

[0017] As a further improvement of the present invention, the construction location is a embankment section; in process (6), the process of constructing the green area is as follows:

[0018] The soil on top of the first roadbed was turned over and loosened by sun exposure, and then seedlings and turf were planted to restore the greenery above the first roadbed.

[0019] As a further improvement of the present invention, the construction location is an excavated road section; in process (2), the construction of the two roadbeds is as follows:

[0020] After leveling the site, excavation is carried out directly on the construction site to the top surface line of the two roadbeds. At this time, the soil condition is tested to determine whether the compaction degree and strength of the underlying layer after compaction can meet the strength index requirements of the roadbed. If they meet the requirements, compaction construction of the two roadbeds is carried out directly. If they do not meet the requirements, the soil layer is excavated to the bottom surface line of the roadbed. After that, the ground is compacted and backfilled after compaction. Finally, the first roadbed and the second roadbed are formed.

[0021] As a further improvement of the present invention, the construction location is an excavated road section; in process (6), the process of constructing the green area is as follows:

[0022] Backfill the top of the first roadbed with slope soil, and plant seedlings and turf on the backfilled slope soil to restore the greenery above the first roadbed.

[0023] As a further improvement of the present invention, the construction location is an excavated road section; in process (6), the slope soil backfilling operation is carried out in layers. After the subbase construction is completed, the first layer of slope soil is backfilled on one side; after the base construction is completed, the second layer of slope soil is backfilled on one side; after the surface construction is completed, the last layer of slope soil is constructed on one side.

[0024] As a further improvement of the present invention, in process (2), the first roadbed is used as the foundation for the construction access road, and the second roadbed is used successively as the foundation for the construction access road and the emergency road; and

[0025] The compaction standards for both roadbeds are the same and meet the following requirements: the compaction degree within 30cm of the roadbed is not less than 94%, and the compaction degree of the foundation at the bottom of the roadbed is not less than 93%.

[0026] As a further improvement of the present invention, in process (3), the thickness of the cement mortar is 3cm~5cm;

[0027] and / or

[0028] In process (8), the minimum compaction thickness of the last layer of fill material on the top surface of the third roadbed shall not be less than 10cm.

[0029] As a further improvement of the present invention, in process (8), an tack coat is applied between the base layer, the base layer, and the top layer; and

[0030] The surface layer is made of fine-grained modified asphalt concrete (AC-13C) with a thickness of 4cm to 8cm; and / or, the tack coat is made of PC-3 cationic emulsified asphalt; and / or, the base layer is made of reinforced concrete with a thickness of 18cm to 22cm and a flexural strength greater than 4.5MPa; and / or, the subbase layer is made of cement concrete with a thickness of 18cm to 22cm and a flexural strength greater than 4.5MPa.

[0031] In another aspect, the present invention provides an emergency road layout structure suitable for suspended monorails, which is constructed according to the construction method for the emergency road layout structure suitable for suspended monorails.

[0032] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0033] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include:

[0034] (1) The construction method of the emergency road layout structure applicable to suspended monorail of the present invention preferably involves setting up a first roadbed, a second roadbed, and a third roadbed, and successively completing the construction of the construction access road, vegetation belt, and emergency road structure. This effectively improves the functionality of the emergency road structure, realizes the combined setting of multiple roads, simplifies the construction process of the emergency road layout structure of suspended monorail, shortens the construction cycle, reduces construction costs, and promotes the application of suspended monorail transportation.

[0035] (2) The construction method of the present invention for emergency road layout structure applicable to suspended monorails effectively meets the construction needs under different construction conditions and improves the compatibility and flexibility of the construction method by setting up corresponding construction processes for embankment sections and cut sections respectively.

[0036] (3) The emergency road layout structure of the present invention is applicable to suspended monorail. It is constructed and prepared by using the construction method of the optimized emergency road layout structure. It has a simple structure and strong functionality. It can effectively meet the needs of setting up and using emergency roads for suspended monorail transportation, and meet the needs of emergency rescue, maintenance, subsequent construction and connection with park greenways for suspended monorail.

[0037] (4) The construction method of the emergency road layout structure applicable to the suspended monorail in this invention is simple in steps and convenient in construction. It can effectively meet the construction requirements of the emergency road layout structure on one side of the suspended monorail line, and meet the construction requirements of the initial construction access road during the emergency road construction process. There is no need to construct the corresponding roadbed structure, which reduces the repeated construction and excessive demolition of the construction road structure, saves material and labor costs, improves the construction efficiency of the emergency road layout structure, and meets the requirements of economy and practicality. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a construction flowchart of an emergency road layout structure applicable to suspended monorails in an embodiment of the present invention;

[0040] Figure 2 This is a schematic cross-sectional view of the initial layout structure of the emergency road during construction in the embankment section in Embodiment 1 of the present invention;

[0041] Figure 3 This is a schematic cross-sectional view of the emergency road layout structure after completion in the embankment section construction in Embodiment 1 of the present invention;

[0042] Figure 4 This is a schematic cross-sectional view of the initial layout structure of the emergency road during excavation in Embodiment 2 of the present invention;

[0043] Figure 5 This is a schematic diagram of the end face of the emergency road layout structure after completion in the excavation section in Embodiment 2 of the present invention;

[0044] Figure 6 This is a schematic diagram of the plan layout of the suspended monorail transit structure after the construction emergency road layout structure in a specific embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0046] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0050] Example:

[0051] Please see Figure 1 The preferred embodiment of the present invention provides a construction method for an emergency road layout structure suitable for suspended monorails, which preferably includes the following steps:

[0052] (1) Determine the construction location of the emergency road layout structure and level it into a construction site for construction;

[0053] Specifically, during actual construction, a construction location for the emergency road layout structure is selected on one side of the longitudinal line of the suspended monorail to be constructed; thereafter, the site is leveled and the natural ground is transformed into the construction site required for construction according to the construction requirements.

[0054] (2) On the construction site, construct the first roadbed and the second roadbed; wherein the first roadbed and the second roadbed are arranged sequentially along the transverse direction of the suspended monorail, and the first roadbed is located on the side of the second roadbed away from the suspended monorail line.

[0055] Before actual construction, the construction widths of the first and second roadbeds need to be determined according to the design drawings, and the construction boundaries of the two roadbeds need to be defined. In a preferred embodiment, the construction width of the first roadbed is preferably 10-12m, the construction width of the second roadbed is preferably 8-10m, and the lateral distance between the boundary of the second roadbed away from the first roadbed and the suspended rail transit support column is preferably within 3m.

[0056] More specifically, in actual setup, the width of the first and second roadbeds should be sufficient to accommodate the operation space of large construction machinery such as hoisting suspended monorail beams during construction.

[0057] Furthermore, in actual construction, there are usually two scenarios for the construction of the first and second roadbeds, such as... Figure 2 , Figure 4 As shown in .

[0058] Among them, Figure 2 In the scenario shown, the construction site is located in an embankment section. Therefore, the preferred construction process for both roadbeds is as follows:

[0059] After leveling the site, the topsoil is removed. In a preferred embodiment, the thickness of the removed topsoil is preferably 20cm to 40cm, for example, 30cm. Then, the soil condition is tested to determine whether the compaction and strength of the underlying layer after compaction meet the strength requirements of the roadbed. If they do, the roadbed is directly filled and backfilled. If not, the soil layer is excavated to the bottom line of the roadbed, and then the ground is compacted (preferably using a heavy roller), followed by backfilling. Finally, the first and second roadbeds are formed.

[0060] exist Figure 4 In the scenario shown, the construction site is located in an excavation section. The construction process for both roadbeds is as follows:

[0061] After leveling the site, excavation is carried out directly on the construction site to the top surface line of the two roadbeds. At this time, the soil condition is tested to determine whether the compaction degree and strength of the underlying layer after compaction can meet the strength index requirements of the roadbed. If they meet the requirements, compaction construction of the two roadbeds is carried out directly. If they do not meet the requirements, the soil layer is excavated to the bottom surface line of the roadbed. After that, the ground is compacted (preferably using a heavy roller), and backfilling is carried out after compaction. Finally, the first and second roadbeds are formed.

[0062] Furthermore, during the actual construction of the two roadbeds, it is preferable to proceed with processes such as paving, compaction, and leveling, ensuring that the flatness and compaction of both roadbeds meet the load requirements of the subsequent roads. Simultaneously, the first roadbed is primarily used as the foundation for the construction access road, while the second roadbed serves as the foundation for both the initial construction access road and the subsequent emergency road.

[0063] In the theoretical design, since the second roadbed requires emergency road construction later, its compaction standard should theoretically be higher than that of the first roadbed. However, considering that the two roadbeds can be constructed simultaneously, in actual implementation, the compaction standard of the first roadbed is set to be the same as that of the second roadbed to facilitate the rapid construction and overall use of the access road.

[0064] In a preferred embodiment, the compaction degree of the two roadbeds preferably meets the following requirements: the compaction degree within 30cm of the roadbed is not less than 94%, and the compaction degree of the foundation at the bottom of the roadbed (at the bottom line of the roadbed) is not less than 93%.

[0065] More preferably, considering that the excavated road section will be backfilled with slope soil later, in the preferred embodiment, the soil excavated during the excavation of the second roadbed is preferably retained for later use.

[0066] (3) Apply a certain thickness of cement mortar to the first and second roadbeds. After the mortar has been laid and formed, a construction access road is formed on the top of the two roadbeds.

[0067] In a preferred embodiment, the thickness of the cement mortar spread on the top of the two roadbeds is preferably 3cm to 5cm.

[0068] (4) Using the construction access road, the construction of the suspended monorail line is carried out along the longitudinal direction of the suspended monorail transit; the construction content includes at least the construction of the track beams, stations and other structures.

[0069] (5) Remove the mortar layer on the first and second roadbeds and restore the soil layer on top of the two roadbeds;

[0070] At this point, the first and second roadbeds have completed their function as the foundation for the construction access road.

[0071] (6) A green area is constructed above the first roadbed, and a vegetation belt is formed on the side of the second roadbed away from the suspended monorail line;

[0072] For embankment sections, it is preferable to directly turn over and loosen the soil on top of the first roadbed, then plant seedlings and turf to restore the greenery above the first roadbed, thereby forming a green belt or vegetation belt on the side of the second roadbed away from the suspended monorail line.

[0073] For excavated sections, it is preferable to backfill the slope soil on top of the first roadbed and plant seedlings and turf on the backfilled slope soil to restore the greenery above the first roadbed, thereby forming a green belt or vegetation belt on the side of the second roadbed away from the suspended monorail line.

[0074] (7) Construct a third roadbed on top of the second roadbed, and ensure that the compaction standard of the third roadbed meets the requirements for use as an emergency road.

[0075] In a preferred embodiment, the emergency road is preferably a multi-functional road that combines construction access road (for subsequent construction), park greenway, rescue channel, and maintenance road, which can meet a variety of usage needs.

[0076] More specifically, in actual installation, the minimum compacted thickness of the last layer of fill material on the top surface of the third subgrade should not be less than 10cm.

[0077] (8) On the third roadbed, the subbase, base course, and surface course are laid sequentially from bottom to top to form a structure like... Figure 3 , Figure 5 The emergency road structure shown;

[0078] In actual construction, to ensure reliable bonding between concrete and asphalt concrete, two materials with different properties, it is preferable to apply tack coat and primer between the subbase, base course and surface course to ensure the formation of a complete pavement structure.

[0079] More specifically, in the preferred embodiment, the surface layer is preferably made of fine-grained modified asphalt concrete (AC-13C) with a thickness of 4cm to 8cm, and the tack coat is preferably made of PC-3 cationic emulsified asphalt; the base layer is preferably made of reinforced concrete with a thickness of 18cm to 22cm and a flexural strength greater than 4.5MPa; and the subbase layer is preferably made of cement concrete with a thickness of 18cm to 22cm and a flexural strength greater than 4.5MPa.

[0080] Meanwhile, when the construction is in the excavation section, the backfilling of the slope soil in process (6) is preferably carried out in layers according to the layered construction of each layer of the emergency road structure. That is, after the subbase construction is completed, the first layer of slope soil is backfilled on one side; after the base construction is completed, the second layer of slope soil is backfilled on one side; after the surface construction is completed, the last layer of slope soil is constructed on one side to restore the ground form on one side of the road.

[0081] Furthermore, for emergency road construction on embankment sections, the structure above the third subgrade should preferably be higher than the ground level on both sides of the road, such as... Figure 3 As shown in the figure, it is preferable to construct road edge structures along the longitudinal direction on both sides of the third roadbed, which are preferably formed by casting reinforced concrete.

[0082] By carrying out the above processes sequentially, the construction of the emergency road layout structure for suspended monorail transit can be accurately realized, resulting in an emergency road layout structure suitable for suspended monorails.

[0083] The construction method for emergency road layout structures applicable to suspended monorails in this invention is simple in steps and convenient in construction. It can effectively meet the construction requirements of emergency road layout structures on one side of suspended monorail lines, and meet the initial construction access road construction requirements during the emergency road construction process. It does not require additional construction of corresponding roadbed structures, reduces repeated construction and excessive demolition of construction road structures, saves material and labor costs, improves the construction efficiency of emergency road layout structures, and meets the requirements of economy and practicality.

[0084] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A construction method for an emergency road layout structure suitable for suspended monorails, characterized in that, The process includes the following: (1) Determine the construction location of the emergency road layout structure and level it into a construction site for construction; (2) Construct the first roadbed and the second roadbed on the construction site; wherein the first roadbed and the second roadbed are arranged sequentially along the transverse direction of the suspended monorail, and the first roadbed is located on the side of the second roadbed away from the suspended monorail line. (3) Apply a certain thickness of cement mortar to the first and second roadbeds to form a construction access road on the top of the two roadbeds; (4) Using the construction access road, the construction of the suspended monorail line is carried out along the longitudinal direction of the suspended monorail transit. (5) Remove the mortar layer on the first and second roadbeds and restore the soil layer on top of the two roadbeds; (6) A green area is constructed above the first roadbed, and a vegetation belt is formed on the side of the second roadbed away from the suspended monorail line; (7) A third roadbed with a compaction standard that meets the requirements for emergency road use shall be constructed on top of the second roadbed; (8) On the third roadbed, the subbase, base and surface layers are laid from bottom to top to form an emergency road structure.

2. The construction method for an emergency road layout structure applicable to a suspended monorail according to claim 1, characterized in that, The construction site is a embankment section; In process (2), the construction process of the two roadbeds is as follows: After leveling the site, the topsoil of the original ground is removed. Then, the soil condition is tested to determine whether the compaction and strength of the underlying layer after compaction can meet the strength index requirements of the roadbed. If it meets the requirements, the roadbed filling and backfilling can be carried out directly. If the conditions are not met, the soil layer will be excavated to the bottom line of the roadbed. After that, the ground will be compacted and backfilled after compaction. Ultimately, the first and second roadbeds were formed.

3. The construction method for emergency road layout structures applicable to suspended monorails according to claim 2, characterized in that, In process (6), the process of creating the green area is as follows: The soil on top of the first roadbed was turned over and loosened by sun exposure, and then seedlings and turf were planted to restore the greenery above the first roadbed.

4. The construction method for an emergency road layout structure suitable for suspended monorails according to claim 1, characterized in that, The construction location is a road section requiring excavation. In process (2), the construction process of the two roadbeds is as follows: After leveling the site, excavation is carried out directly on the construction site to the top surface line of the two roadbeds. At this time, the soil condition is tested to determine whether the compaction degree and strength of the underlying layer after compaction can meet the strength index requirements of the roadbed. If they meet the requirements, compaction construction of the two roadbeds is carried out directly. If the conditions are not met, the soil layer will be excavated to the bottom line of the roadbed. After that, the ground will be compacted and backfilled after compaction. Ultimately, the first and second roadbeds were formed.

5. The construction method for an emergency road layout structure suitable for suspended monorails according to claim 4, characterized in that, In process (6), the process of creating the green area is as follows: Backfill the top of the first roadbed with slope soil, and plant seedlings and turf on the backfilled slope soil to restore the greenery above the first roadbed.

6. The construction method for an emergency road layout structure suitable for suspended monorails according to claim 5, characterized in that, In process (6), the slope backfilling operation is carried out in layers. After the subbase construction is completed, the first layer of slope soil is backfilled on one side; after the base construction is completed, the second layer of slope soil is backfilled on one side; after the surface construction is completed, the last layer of slope soil is constructed on one side.

7. A construction method for an emergency road layout structure applicable to a suspended monorail according to any one of claims 1 to 6, characterized in that, In process (2), the first roadbed was used as the foundation for the construction access road, and the second roadbed was used successively as the foundation for the construction access road and the emergency road; and The compaction standards for both roadbeds are the same and meet the following requirements: the compaction degree within 30cm of the roadbed is not less than 94%, and the compaction degree of the foundation at the bottom of the roadbed is not less than 93%.

8. A construction method for an emergency road layout structure applicable to a suspended monorail according to any one of claims 1 to 6, characterized in that, In process (3), the thickness of the cement mortar is 3cm~5cm; and / or In process (8), the minimum compaction thickness of the last layer of fill material on the top surface of the third roadbed shall not be less than 10cm.

9. A construction method for an emergency road layout structure applicable to a suspended monorail according to any one of claims 1 to 6, characterized in that, In process (8), a tack coat is applied between the subbase, base course, and topcoat layers; and The surface layer is made of fine-grained modified asphalt concrete with a thickness of 4cm to 8cm; and / or, the tack coat is made of PC-3 cationic emulsified asphalt; and / or, the base layer is made of reinforced concrete with a thickness of 18cm to 22cm and a flexural strength greater than 4.5MPa; and / or, the subbase layer is made of cement concrete with a thickness of 18cm to 22cm and a flexural strength greater than 4.5MPa.

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