Reinforcement Structure and Construction Method for the Transition Section between High-Speed Railway Bridges and Roadbeds in Expansive Soil Areas

Abstract

The present invention provides a reinforcement structure and a construction method thereof for a high-speed railway road-bridge transition section in an expansive soil area. The reinforcement structure of the transition section includes an expansive soil foundation reinforcement structure and a transition section reinforcement structure. The expansive soil foundation reinforcement structure includes an expansive soil foundation and a screw pile array inserted into the expansive soil foundation. The transition section reinforcement structure includes a subgrade transition section and a cushion section located below the subgrade transition section. The cushion section includes a cushion main body and an adjustment component for adjusting the deformation of the expansive soil foundation. The adjustment component includes an EPS layer, a plurality of inflatable adjustment bags embedded in the EPS layer, and a pressure regulator. The number of the inflatable adjustment bags is the same as the number of prestressed screw piles in the screw pile array, and one inflatable adjustment bag is arranged directly opposite above each prestressed screw pile. The reinforcement structure provided by the present invention can control the heave deformation and settlement deformation of the expansive soil foundation and ensure the stability of the deformation.

Description

Technical Field

[0001] The present invention belongs to the technical field of reinforcement treatment of expansive soil foundations in geotechnical engineering, and particularly relates to a reinforcement structure and construction method applied to the bridge - roadbed transition section of high - speed railways in expansive soil areas. Background Art

[0002] China is one of the countries with the widest distribution of expansive soil. Affected by topographical conditions, many high - speed railways inevitably need to be constructed in expansive soil areas. The bridge - roadbed transition section of high - speed railways is a special section in the high - speed railway line, connecting the bridge and the subgrade. Due to the different stiffnesses, differential settlement will occur between the abutment and the subgrade, which will have a very serious impact on the safe operation of trains and the comfort of passengers. Expansive soil is known as the "cancer" in the engineering field. For the bridge - roadbed transition section located in expansive soil areas, differential settlement and the swelling - shrinkage effect of expansive soil need to be strictly controlled.

[0003] At present, most high - speed railways use cement - stabilized macadam as the bridge - roadbed transition section to reduce the stiffness difference, and this method can well control differential settlement. However, when this method is applied to expansive soil areas, it cannot achieve good results. Due to the special engineering properties of expansive soil, the design of the bridge - roadbed transition section becomes more complex. Therefore, it is of great engineering significance and application prospect to propose a composite structure applied to the bridge - roadbed transition section of high - speed railways in expansive soil areas. Summary of the Invention

[0004] The purpose of the present invention is to provide a reinforcement structure applied to the bridge - roadbed transition section of high - speed railways in expansive soil areas. This reinforcement structure can effectively control the differential settlement deformation of the line caused by water - induced swelling, water - loss shrinkage and stiffness difference in the bridge - roadbed transition section of high - speed railways in expansive soil areas, ensure that the settlement deformation of the bridge - roadbed transition section of high - speed railways in expansive soil areas meets the specification requirements, and ensure the smoothness of the line.

[0005] To achieve the above purpose, the present invention provides a reinforcement structure applied to the bridge - roadbed transition section of high - speed railways in expansive soil areas. The high - speed railway bridge - roadbed includes an abutment and a subgrade arranged at an interval from the abutment. The subgrade is underlain by expansive soil. The reinforcement structure of the transition section includes:

[0006] An expansive soil foundation reinforcement structure, which includes an expansive soil foundation and a screw pile array vertically inserted into the expansive soil foundation from the top surface of the expansive soil foundation;

[0007] Transition section reinforcement structure, the transition section reinforcement structure includes a subgrade transition section composed of cast-in-place concrete and foam concrete, the abutment and the subgrade are respectively arranged at both ends of the subgrade transition section and are both connected to the subgrade transition section; the transition section reinforcement structure further includes a cushion section arranged on the top surface of the expansive soil foundation, and one side of the cushion section away from the expansive soil foundation abuts against the subgrade transition section and the subgrade, where:

[0008] The cushion section includes a cushion main body composed of gravel and geogrid, and an adjustment component for adjusting the deformation of the expansive soil foundation. The cushion main body is located on the side close to the subgrade transition section. The adjustment component includes an EPS layer clamped between the cushion main body and the expansive soil foundation reinforcement structure, a plurality of inflatable adjustment bags embedded in the EPS layer, and a pressure regulator for adjusting the pressure in the plurality of inflatable adjustment bags based on the settlement deformation data of the cushion section. The number of the inflatable adjustment bags is the same as the number of the prestressed screw piles in the screw pile array, and one inflatable adjustment bag is arranged directly above each prestressed screw pile.

[0009] In a specific embodiment, taking the top surface of the expansive soil foundation as a reference plane, the screw pile array includes a plurality of first screw pile groups arranged at intervals in the width direction, and a plurality of second screw pile groups arranged at intervals in the width direction. The plurality of first screw pile groups and the plurality of second screw pile groups are arranged in a staggered manner, and the positions of the prestressed screw piles in adjacent first screw pile groups and second screw pile groups are staggered.

[0010] In a specific embodiment, taking the top surface of the expansive soil foundation as a reference plane, both the first screw pile group and the second screw pile group include a plurality of prestressed screw piles arranged at intervals in the length direction. Among them, the Mth prestressed screw pile in the second screw pile group is located on the symmetry plane of the Mth and (M + 1)th prestressed screw piles in the first screw pile group, or the Mth prestressed screw pile in the first screw pile group is located on the symmetry plane of the Mth and (M + 1)th prestressed screw piles in the second screw pile group, where M is an integer greater than or equal to 1.

[0011] In a specific embodiment, along the direction from the abutment to the subgrade, the lengths of the prestressed screw piles in each first screw pile group and the lengths of the prestressed screw piles in each second screw pile group decrease in sequence.

[0012] In a specific embodiment, the prestressed screw pile includes a pile body and prestressed steel bars arranged in the pile body. The pile body includes a cylindrical first part and a second part connected to the first part. The first part abuts against the inflatable adjustment package. The second part is a threaded rod. The inflatable adjustment package is cylindrical, and the size of the cross-section of the inflatable adjustment package is exactly the same as the size of the cross-section of the first part.

[0013] In a specific embodiment, the inflatable adjustment package includes an inflatable shell with an inflation port, a laser rangefinder arranged at the center of the bottom of the inflatable shell, and a reflector arranged at the top of the inflatable shell and in the detection direction of the laser rangefinder. The inflatable shell is a cylindrical shell. The laser rangefinder is electrically connected to the controller of the pressure regulator. The inflation port of the inflatable shell is connected to the inflation component of the pressure regulator.

[0014] In a specific embodiment, the upper surface of the inflatable adjustment package is flush with the upper surface of the EPS layer, and the lower surface of the inflatable adjustment package is flush with the lower surface of the EPS layer.

[0015] In a specific embodiment, the subgrade transition section includes a cast-in-place concrete body formed by casting, multiple groups of foam concrete sandwiched between the cast-in-place concrete body and the subgrade, and a plurality of connecting rods arranged at intervals along the height direction of the abutment. One end of each connecting rod is connected to the abutment, and the other end sequentially passes through the reserved holes of the cast-in-place concrete body and a group of the foam concrete groups and is inserted into the subgrade. Barbs are provided at the other end of the connecting rod inserted into the subgrade.

[0016] In a specific embodiment, the transition section reinforcement structure further includes a bed layer covering the subgrade transition section and the side of the subgrade away from the cushion section. From the bed layer to the cushion section direction, the cast-in-place concrete body is in the shape of an inverted right-angled trapezoid with a longer upper side and a shorter lower side.

[0017] The present invention also provides a construction method for the reinforcement structure described above, including the following steps:

[0018] Step (1), based on the design requirements of the high-speed rail transition section and the on-site geological conditions, determine the number, size, and arrangement method of the prestressed screw piles forming the screw pile array;

[0019] Step (2), provide a plurality of foam concretes with reserved holes and a plurality of prestressed screw piles. Each prestressed screw pile is prestressed by the pre-tensioning method through prestressed steel bars and cured to the design strength;

[0020] Step (3): Install the prestressed screw columns according to the layout of the screw pile array, and control the verticality and pile top elevation of the prestressed screw columns to meet the design requirements. Backfill and compact the pile holes with the original soil.

[0021] Step (4): Lay the EPS layer and multiple inflatable adjustment packages on the top surface of the expansive soil foundation according to the design requirements, and fill high-pressure gas into the inflatable adjustment packages to control the elevation of the upper surface of the inflatable adjustment packages to be consistent with the upper surface of the EPS.

[0022] Step (5): Lay the main body of the cushion on the upper surfaces of the EPS layer and the multiple inflatable adjustment packages in a preset manner to form a cushion.

[0023] Step (6): Lay a layer of foam concrete on the top surface of the cushion. When laying, make the reserved holes form a through hole, and pass the connecting rod through the reserved holes to the abutment.

[0024] Step (7): Backfill and compact the subgrade to make the elevation of the subgrade consistent with that of the foam concrete.

[0025] Step (8): Repeat Step (6) and Step (7) to lay the foam concrete and backfill and compact the subgrade in layers. When the design elevation is met, pour the concrete body at one time and cure it to the design strength. Finally, lay the bed layer.

[0026] The beneficial effects of the present invention at least include:

[0027] 1. The transition section reinforcement structure provided by the present invention sets a subgrade transition section between the abutment and the subgrade, sets a cushion section between the subgrade and the subgrade transition section and the expansive soil foundation, and arranges a screw pile array in the expansive soil foundation. Among them, the cushion section includes a cushion main body composed of gravel and geogrid, and an adjustment component for adjusting the deformation of the expansive soil foundation. The cushion main body is located on the side close to the subgrade transition section. The adjustment component includes an EPS layer clamped between the cushion main body and the expansive soil foundation reinforcement structure, a plurality of inflatable adjustment bags embedded in the EPS layer, and a pressure regulator for adjusting the pressure in a plurality of the inflatable adjustment bags based on the settlement deformation data of the cushion section. The number of the inflatable adjustment bags is the same as the number of prestressed screw piles in the screw pile array, and one of the inflatable adjustment bags is arranged directly opposite above each of the prestressed screw piles. In this way, on the one hand, when the expansive soil foundation swells due to water immersion, the EPS layer can absorb the generated swelling potential energy, transfer the uplift deformation amount caused by water immersion swelling to the shrinkage deformation of the EPS layer, thereby reducing the uplift deformation of the expansive soil foundation. When the expansive soil foundation shrinks due to water loss, the EPS layer will release the absorbed potential energy and generate a rebound deformation to reduce the settlement deformation of the expansive soil subgrade. On the other hand, under the repeated load of train operation, the cushion section can effectively transfer the load to the expansive soil foundation. The inflatable adjustment bag can monitor the deformation dynamics of the expansive soil subgrade in real time, and can control the settlement deformation of the cushion section by adjusting the internal gas pressure of the inflatable adjustment bag, ensuring the deformation stability of the transition section subgrade and meeting the operation requirements of the train for smoothness and safety.

[0028] 2. The subgrade transition section provided by the present invention is composed of cast concrete in an inverted trapezoidal shape and multiple groups of foam concrete, and is connected by connecting rods. One end of the connecting rod is connected to the abutment, and the other end of the connecting rod is inserted into the subgrade. In this way, the cast concrete body and multiple groups of foam concrete groups are arranged in a certain order, so that in the transition section from the abutment to the subgrade, the stiffness decreases in turn, which can well solve the differential settlement generated under the repeated load of the train, the water immersion swelling and water loss shrinkage of the expansive soil foundation. At the same time, the connecting rods connect the abutment, the inverted trapezoidal concrete body, the foam concrete and the subgrade in turn, which can increase the stiffness of the transition section and form a coordinated whole to prevent large differential settlement deformation.

[0029] 3. The subgrade transition section provided by the present invention is jointly composed of cast concrete and foam concrete, making full use of the excellent characteristics of foam concrete such as light weight, good waterproof performance and convenient construction. It can effectively reduce the additional stress of the expansive soil foundation, weaken the swelling and shrinkage effect of the expansive soil, control the differential settlement, and is convenient for construction. No harmful substances are generated during the construction process, meeting the environmental protection requirements.

[0030] IV. The up-and-down segmented design of the prestressed screw pile provided in the present invention conforms to the distribution law of additional stress, enabling the forces on the pile body and the soil to be coordinated, meeting the requirements of stress sharing ratio and stiffness change, effectively increasing the side friction resistance of the pile, improving the vertical bearing capacity, reducing the settlement deformation of the expansive soil foundation. At the same time, on the one hand, the prestressed steel bars can increase the bearing capacity of the pile body, and on the other hand, they can improve the tensile strength of the pile body, reducing the swelling deformation of the expansive soil foundation due to water absorption, and controlling the settlement deformation and swelling deformation of the reinforced expansive soil foundation within the specification requirements.

[0031] In addition to the purposes, features, and advantages described above, the present invention has other purposes, features, and advantages. The following will refer to the drawings to further elaborate on the present invention in detail. Brief Description of the Drawings

[0032] Figure 1 It is a schematic structural view of an angle of a reinforcement structure applied to the bridge-road transition section of a high-speed railway in an expansive soil area provided by an embodiment of the present invention;

[0033] Figure 2 is Figure 1 a schematic structural view of an angle of the screw pile array shown;

[0034] Figure 3 is Figure 2 a three-dimensional structural view of the prestressed screw pile in the screw pile array shown;

[0035] Figure 4 is Figure 1 a schematic structural view of an angle of the connecting rod shown;

[0036] Figure 5 is Figure 1 a schematic structural view of an angle of the cushion section shown;

[0037] Figure 6 is Figure 5 a schematic structural view of the EPS layer and the inflatable adjustment package shown.

[0038] Explanation of the Reference Numerals in the Drawings:

[0039] Detailed Embodiment

[0040] The following will elaborate on the embodiments of the present invention in detail with reference to the drawings. However, the present invention can be defined and covered by the claims in various different embodiments.

[0041] Please refer to Figure 1, the present invention provides a reinforcement structure for the high-speed railway road and bridge transition section in the expansive soil area. The high-speed railway road and bridge includes a bridge abutment 200 and a subgrade 300 arranged at an interval from the bridge abutment 200. The subgrade 300 is underlain by expansive soil. The present invention reinforces the transition section connecting the bridge abutment 200 and the subgrade 300, and reinforces the expansive soil under the subgrade 300 to effectively control the differential settlement deformation of the high-speed railway road and bridge transition section in the expansive soil area caused by soaking expansion, water loss shrinkage and stiffness difference, ensure that the settlement deformation of the high-speed railway road and bridge transition section in the expansive soil area meets the specification requirements, and the deformation is stable, ensure the smoothness of the line, and meet the requirements of the stable and safe operation of the train.

[0042] The reinforcement structure of the transition section provided by the present invention includes an expansive soil foundation reinforcement structure 10 and a transition section reinforcement structure 20. Among them, the subgrade 300 is located above the expansive soil foundation reinforcement structure 10, and the bridge abutment 200 is located at one end of the transition section reinforcement structure 20 away from the subgrade 300.

[0043] The expansive soil foundation reinforcement structure 10 includes an expansive soil foundation 11 and a screw pile array 12 vertically inserted into the expansive soil foundation 11 from the top surface of the expansive soil foundation 11.

[0044] The present invention reinforces the expansive soil foundation 11 through the screw pile array 12 to control the settlement deformation and heave deformation of the expansive soil foundation within the specification requirements.

[0045] In this embodiment, the multiple prestressed screw piles forming the screw pile array 12 are arranged according to a preset arrangement method. In this way, the force can be better evenly distributed, with an even transition, and large differential settlement can be prevented.

[0046] Please refer to Figure 2 and Figure 3 , in this embodiment, the arrangement method is a plum blossom shape distribution. Specifically, taking the top surface 111 of the expansive soil foundation as a reference surface, the screw pile array 12 includes multiple first screw pile groups 121 arranged at intervals in the width direction and multiple second screw pile groups 122 arranged at intervals in the width direction. The multiple first screw pile groups 121 and the multiple second screw pile groups 122 are arranged in an alternating manner, and the positions of the prestressed screw piles in the adjacent first screw pile group 121 and second screw pile group 122 are staggered.

[0047] The multiple first screw pile groups and the multiple second screw pile groups are arranged in an alternating pattern along the first direction. It can be understood that they are arranged in the following order along the width direction: first screw pile group, second screw pile group, first screw pile group, second screw pile group, first screw pile group, second screw pile group... or in the order of second screw pile group, first screw pile group, second screw pile group, first screw pile group, second screw pile group, first screw pile group...

[0048] Please refer to Figure 2 , from Figure 2 it can be seen that the top surface of the expansive soil foundation is rectangular. The width direction can be understood as Figure 2 the Y direction on []. In this embodiment, the number of the first screw pile groups is three, and the number of the second screw pile groups is four. From top to bottom, they are in the order of second screw pile group, first screw pile group, second screw pile group, first screw pile group, second screw pile group, first screw pile group, second screw pile group.

[0049] In this embodiment, Figure 2 the X direction on [] is the direction from the abutment to the subgrade.

[0050] It should be noted that in other embodiments, it is also possible that the length of the top surface of the expansive soil foundation in the X direction is less than the length in the Y direction. It can be understood that in this way, the width direction in the present invention actually corresponds to the length direction of the top surface.

[0051] The staggered arrangement of the positions of the prestressed screw piles in the adjacent first screw pile group 121 and the second screw pile group 122 means that the coordinates of the Mth prestressed screw pile in the adjacent first screw pile group 121 and the Mth prestressed screw pile in the second screw pile group 122 in the X direction are different.

[0052] Preferably, taking the top surface of the expansive soil foundation as a reference plane, both the first screw pile group 121 and the second screw pile group 122 include a plurality of screw piles 125 arranged at intervals along the length direction. Among them, the Mth prestressed screw pile in the second screw pile group 122 is located on the symmetry plane between the Mth prestressed screw pile and the (M + 1)th prestressed screw pile in the first screw pile group 121, or the Mth prestressed screw pile in the first screw pile group 121 is located on the symmetry plane between the Mth prestressed screw pile and the (M + 1)th prestressed screw pile in the second screw pile group 122, where M is an integer greater than or equal to 1.

[0053] In this embodiment, the Mth prestressed screw pile in the second screw pile group 122 is located on the symmetry plane between the Mth prestressed screw pile and the (M + 1)th prestressed screw pile in the first screw pile group 121. It can be understood that the distance between the Mth prestressed screw pile in the second screw pile group 122 and the Mth prestressed screw pile in the first screw pile group 121 is the same as the distance between the Mth prestressed screw pile in the second screw pile group 122 and the (M + 1)th prestressed screw pile in the first screw pile group 121.

[0054] Preferably, the distance between adjacent first and second screw pile groups is L, and the distance between the Mth prestressed screw pile in the second screw pile group and the Mth / (M + 1)th prestressed screw pile in the first screw pile group is S, where L = S.

[0055] It should be noted that the distances mentioned above all refer to the distance between the central axis of one prestressed screw pile and the central axis of another prestressed screw pile.

[0056] Preferably, along the direction from the bridge abutment 200 to the roadbed 300, the lengths of the multiple prestressed screw piles in each first screw pile group 121 and the multiple prestressed screw piles 125 in each second screw pile group 122 decrease in sequence. In this way, the stiffness of the transition section decreases in sequence, the force is reasonable, and the transition is uniform, preventing large differential settlements.

[0057] Preferably, the prestressed screw pile 125 includes a pile body 1251 and prestressed steel bars 1252 arranged in the pile body. The pile body 1251 includes a first part 12511 in a cylindrical shape and a second part 12522 connected to the first part 12511, and the second part 12522 is a threaded rod.

[0058] In this embodiment, the prestressed screw pile 125 is pre-cast in a processing factory. The length of the prestressed steel bars 1252 is the same as the length of the pile body 1251, that is, the prestressed steel bars are arranged throughout the prestressed screw pile 125, and the prestress is applied by the pre-tensioning method.

[0059] In this embodiment, the diameter D of the first part 12511 is 0.5 m to 1.0 m, the inner diameter d of the second part 12512 is 0.3 m to 0.5 m, and the thread height is 5 cm; the length ratio of the first part 12511 to the second part 12512 is not less than 1:2.

[0060] Preferably, L / D = 3 to 5, S / D = 3 to 5, and L = S.

[0061] In the present invention, the up-and-down segmented design of the prestressed screw pile 125 conforms to the distribution law of additional stress, enabling the stress of the pile body and the soil body to be coordinated, meeting the requirements of stress sharing ratio and stiffness change, effectively increasing the side friction resistance of the pile, improving the vertical bearing capacity, reducing the settlement deformation of the expansive soil foundation. At the same time, the prestressed steel bars can, on the one hand, increase the bearing capacity of the pile body, and on the other hand, improve the tensile strength of the pile body, reducing the swelling deformation of the expansive soil foundation due to water absorption, and controlling the settlement deformation and swelling deformation of the reinforced expansive soil foundation within the specification requirements.

[0062] The transition section reinforcement structure 20 includes a subgrade transition section 21 composed of cast concrete and foam concrete, a cushion section 22, and a subgrade bed layer 23. Among them, the subgrade transition section 21 and the subgrade 300 are arranged side by side and are located between the abutment 200 and the subgrade 300; the cushion section 22 is arranged on the top surface of the expansive soil foundation 11, and the side away from the expansive soil foundation 11 abuts against the subgrade transition section 21 and the subgrade 300; the subgrade bed layer 23 is arranged on the surfaces of the subgrade transition section 21 and the subgrade 300 away from the cushion section 22.

[0063] In this embodiment, the upper and lower surfaces of the subgrade transition section 21 and the subgrade 300 are flush, and both are sandwiched between the subgrade bed layer 23 and the cushion section 22.

[0064] In this embodiment, the subgrade transition section 21 includes a cast concrete body 211 formed by casting, multiple groups of foam concrete groups 212 sandwiched between the cast concrete body 211 and the subgrade 300, and a plurality of connecting rods 213 spaced along the height direction of the abutment 200. One end of each connecting rod 213 is connected to the abutment 200, and the other end sequentially passes through the reserved holes of the cast concrete body 211 and a group of the foam concrete groups 212 and is inserted into the subgrade 300.

[0065] In this embodiment, the multiple groups of foam concrete groups 212 and the subgrade 300 are laid and constructed in a layered manner, and the cast concrete body 211 is integrally cast at one time.

[0066] In this embodiment, in the direction from the subgrade bed layer 23 to the cushion 22 section, the cast concrete body 211 is in the shape of an inverted right-angled trapezoid with a longer upper side and a shorter lower side. After laying the foam concrete groups 212 and installing all the connecting rods 213, it is integrally cast at one time and cured to the design strength.

[0067] In the present invention, the inverted trapezoidal cast concrete body and the foam concrete groups are arranged in a certain order successively, so that in the transition section from the abutment to the subgrade, the stiffness decreases successively, which can well solve the differential settlement generated in the transition section under the repeated loads of the train, the swelling of the expansive soil foundation when soaked in water and the shrinkage when losing water; at the same time, the connecting rods connect the abutment, the inverted trapezoidal concrete body, the foam concrete and the subgrade in sequence, which can increase the stiffness of the transition section and form a coordinated whole to prevent large differential settlement deformation.

[0068] In this embodiment, there are three groups of foam concrete groups 212 in total, and each group of foam concrete groups 212 is composed of three foam concretes 2121 located in the same row. Specifically, the foam concrete 2121 is a square-shaped foam concrete block, and a reserved hole for facilitating the passing of the connecting rod 213 is arranged in the middle. The aperture of the reserved hole is 0.5 - 1.0 cm larger than the outer diameter of the connecting rod. The reserved holes of the foam concretes 2121 in each group of foam concrete groups 212 are arranged opposite to each other to facilitate the passing of the connecting rod 213 to be connected as a whole.

[0069] The subgrade transition section 21 makes full use of the excellent characteristics of the foam concrete, such as light weight, good waterproof performance and convenient construction, which can effectively reduce the additional stress of the expansive soil foundation, weaken the swelling and shrinkage effect of the expansive soil, control the differential settlement, and is convenient for construction. No harmful substances are generated during the construction process, meeting the environmental protection requirements.

[0070] Please refer to Figure 4 , preferably, the connecting rod 213 includes a main body part 2131 for connecting the cast concrete body 211 and the foam concrete 2121, and a barbed part 2132 inserted into the subgrade 300. The main body part 2131 is fixedly connected with the abutment 200.

[0071] In this embodiment, the connecting rod 213 is made of construction deformed steel bars with a yield strength greater than 300 Mpa, and threads are provided on the rod body of the main body part 2131.

[0072] In this embodiment, the barbed length of the barbed part 2132 is 3 cm - 5 cm and forms an angle of 45° with the rod body.

[0073] In this embodiment, the outer diameter of the connecting rod 213 is smaller than the aperture of the reserved hole. After the connecting rod connects the foam concrete groups 212, the redundant voids are filled by grouting to ensure their tight combination.

[0074] Please refer to Figure 5 and Figure 6, the cushion section 22 includes a cushion main body 221 composed of crushed stones and geogrid, and an adjustment component 222 for adjusting the deformation of the expansive soil foundation. Among them, the cushion main body 221 is located on one side close to the subgrade transition section 21, and the adjustment component 222 is clamped between the cushion main body 221 and the expansive soil foundation 11.

[0075] In this embodiment, the cushion main body 221 is composed of two layers of crushed stone layers and two layers of geogrid. Specifically, one layer of geogrid is laid respectively in the middle of the two layers of crushed stone layers and under the crushed stone layer far from the subgrade transition section 21. Among them, the thickness of the crushed stone layer is 0.5m - 0.8m, and it is compacted at least twice. The particle size of the crushed stones should be 8 - 30mm. The overlapping of the middle geogrid is welded or tied, and the overlapping width is not less than 10cm, and the connection strength is not less than 80kN / m. The overlapping joints of the upper and lower layers of geogrid are staggered by not less than 0.5m.

[0076] The adjustment component 222 includes an EPS layer 2221 clamped between the cushion main body 221 and the expansive soil foundation reinforcement structure 10, a plurality of inflatable adjustment packages 2222 embedded in the EPS layer 2221, and a pressure regulator for adjusting the pressure in a plurality of the inflatable adjustment packages based on the settlement deformation data of the cushion section. The number of the inflatable adjustment packages 2222 is the same as the number of the prestressed screw piles 125 in the screw pile array, and one of the inflatable adjustment packages 2222 is disposed directly opposite above each of the prestressed screw piles 125.

[0077] In this embodiment, the EPS layer is prepared from expanded polystyrene. When the expansive soil foundation swells due to water immersion, the EPS layer can absorb the generated swelling potential energy, transfer the uplift deformation amount caused by water immersion swelling to the shrinkage deformation of the EPS layer, and thus reduce the uplift deformation of the expansive soil foundation. When the expansive soil foundation shrinks due to water loss, the EPS layer will release the absorbed potential energy and generate a rebound deformation to reduce the settlement deformation of the expansive soil subgrade.

[0078] Preferably, the thickness of the EPS layer is not less than 0.3m.

[0079] In this embodiment, a plurality of inflatable adjustment packages 2222 are arranged in one-to-one correspondence with the prestressed screw piles 125 in the screw pile array. Correspondingly, the arrangement mode of the plurality of inflatable adjustment packages 2222 is the same as the arrangement mode of the prestressed screw piles 125 in the screw pile array.

[0080] In this embodiment, the inflatable adjustment package 2222 abuts against the first part of the prestressed screw pile 125 in the screw pile array.

[0081] In this embodiment, the inflatable adjustment package 2222 is cylindrical in shape, and its height is the same as that of the EPS. The upper surface of the inflatable adjustment package 2222 is flush with the upper surface of the EPS layer, and the lower surface of the inflatable adjustment package is flush with the lower surface of the EPS layer.

[0082] In this embodiment, the size of the cross-section of the inflatable adjustment package 2222 is exactly the same as the size of the cross-section of the first part of the prestressed screw pile.

[0083] Preferably, the inflatable adjustment package 2222 is made of high-strength rubber and filled with high-pressure gas inside.

[0084] Preferably, the inflatable adjustment package 2222 includes an inflatable housing with an inflation port, a laser rangefinder disposed at the center of the bottom of the inflatable housing, and a reflector disposed at the top of the inflatable housing and in the detection direction of the laser rangefinder. The inflatable housing is a cylindrical housing. The laser rangefinder is electrically connected to the controller of the pressure regulator, and the inflation port of the inflatable housing is connected to the inflation component of the pressure regulator.

[0085] The controller of the pressure regulator receives the height data of the laser rangefinder and turns on or off the inflation component of the pressure regulator based on the height data. In this way, under the repeated loads during train operation, the cushion section can effectively transfer the loads to the expansive soil foundation. The inflatable adjustment package can monitor the dynamic deformation of the expansive soil subgrade in real time and can control the settlement deformation of the cushion section by adjusting the internal gas pressure of the inflatable housing, ensuring the deformation stability of the transition section subgrade and meeting the operation requirements of the train for smoothness and safety.

[0086] Based on the height data of the inflatable adjustment package detected by the laser rangefinder, when the settlement or uplift deformation amount of the expansive soil subgrade exceeds the allowable value specified in the code, the inflation component is turned on, and the internal pressure of the inflatable housing is adjusted by filling or releasing gas until the settlement or uplift deformation amount of the expansive soil subgrade is within the allowable value specified in the code, and then the inflation component is turned off.

[0087] Based on the height data of the inflatable adjustment package detected by the laser rangefinder, when the settlement or uplift deformation amount of the expansive soil subgrade exceeds the allowable value specified in the code, the inflation component is turned on, and the internal pressure of the inflatable housing is adjusted by filling or releasing gas until the settlement or uplift deformation amount of the expansive soil subgrade is within the allowable value specified in the code, and then the inflation component is turned off.

[0088] The present invention also provides a construction method for the reinforcement structure described above, including the following steps:

[0089] Step (1): Based on the design requirements of the high-speed rail transition section and the on-site geological conditions, determine the number, size, and arrangement method of the prestressed screw piles forming the screw pile array.

[0090] Step (2): Provide a plurality of foam concretes with reserved holes and a plurality of prestressed screw piles. Each prestressed screw pile is prestressed by the pretensioning method using prestressed steel bars and cured to the design strength.

[0091] Step (3): Install the prestressed screw columns according to the arrangement method of the screw pile array, and control the verticality and pile top elevation of the prestressed screw columns to meet the design requirements. Backfill and compact the pile holes with the original soil.

[0092] Step (4): Lay an EPS layer and a plurality of inflatable adjustment packages on the top surface of the expansive soil foundation according to the design requirements, and fill high-pressure gas into the inflatable adjustment packages to control the elevation of the upper surface of the inflatable adjustment packages to be consistent with the upper surface of the EPS.

[0093] Step (5): Lay the main body of the cushion on the upper surfaces of the EPS layer and the plurality of inflatable adjustment packages in a preset manner to form a cushion.

[0094] Step (6): Lay a layer of foam concrete on the top surface of the cushion. When laying, make the reserved holes form a through hole, and pass the connecting rod through the reserved hole to the abutment.

[0095] Step (7): Backfill and compact the subgrade to make the elevation of the subgrade consistent with that of the foam concrete.

[0096] Step (8): Repeat Step (6) and Step (7), lay the foam concrete and backfill and compact the subgrade in layers. When the design elevation is met, pour the cast concrete body at one time and cure it to the design strength; finally, lay the bed layer.

[0097] The construction method provided by the present invention is simple and convenient, the process is reasonable, and the construction work can be completed efficiently, with good economic and social benefits.

[0098] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions and substitutions can still be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A reinforcement structure applied to the transition section between a high-speed railway bridge and roadbed in an expansive soil area. The high-speed railway bridge and roadbed include a bridge abutment and a roadbed spaced from the bridge abutment. The expansive soil is located below the roadbed. It is characterized in that, The reinforcement structure of the transition section includes: An expansive soil foundation reinforcement structure, which includes an expansive soil foundation and a screw pile array vertically inserted into the expansive soil foundation from the top surface of the expansive soil foundation; A transition section reinforcement structure, which includes a subgrade transition section composed of cast-in-place concrete and foamed concrete. The abutment and the subgrade are respectively arranged at both ends of the subgrade transition section and are both connected to the subgrade transition section. The transition section reinforcement structure also includes a cushion section arranged on the top surface of the expansive soil foundation. One side of the cushion section away from the expansive soil foundation abuts against the subgrade transition section and the subgrade. Among them: The cushion section includes a cushion main body composed of gravel and geogrid, and an adjustment component for adjusting the deformation of the expansive soil foundation. The cushion main body is located on the side close to the subgrade transition section. The adjustment component includes an EPS layer clamped between the cushion main body and the expansive soil foundation reinforcement structure, a plurality of inflatable adjustment bags embedded in the EPS layer, and a pressure regulator for adjusting the pressure in a plurality of the inflatable adjustment bags based on the settlement deformation data of the cushion section. The number of the inflatable adjustment bags is the same as the number of prestressed screw piles in the screw pile array, and one of the inflatable adjustment bags is arranged directly opposite to the top of each prestressed screw pile.

2. The reinforcement structure applied to the bridge-road transition section of high-speed railway in expansive soil area according to claim 1, characterized in that, Taking the top surface of the expansive soil foundation as a reference plane, the screw pile array includes a plurality of first screw pile groups arranged at intervals in the width direction, and a plurality of second screw pile groups arranged at intervals in the width direction. The plurality of first screw pile groups and the plurality of second screw pile groups are arranged in an alternating manner, and the positions of the prestressed screw piles in adjacent first screw pile groups and second screw pile groups are staggered.

3. The reinforcement structure applied to the bridge - road transition section of high - speed railway in expansive soil area according to claim 2, characterized in that, Taking the top surface of the expansive soil foundation as a reference plane, both the first screw pile group and the second screw pile group include a plurality of prestressed screw piles arranged at intervals in the length direction. Among them, the Mth prestressed screw pile in the second screw pile group is located on the symmetry plane between the Mth prestressed screw pile and the (M + 1)th prestressed screw pile in the first screw pile group, or the Mth prestressed screw pile in the first screw pile group is located on the symmetry plane between the Mth prestressed screw pile and the (M + 1)th prestressed screw pile in the second screw pile group, where M is an integer greater than or equal to 1.

4. The reinforcement structure applied to the bridge-road transition section of high-speed railway in expansive soil area according to claim 3, characterized in that, Along the direction from the abutment to the subgrade, the lengths of the prestressed screw piles in each of the first screw pile groups and the lengths of the prestressed screw piles in each of the second screw pile groups decrease in sequence.

5. The reinforcement structure applied to the bridge - road transition section of high - speed railway in expansive soil area according to any one of claims 2 to 4, characterized in that, The prestressed screw pile includes a pile body and prestressed steel bars arranged in the pile body. The pile body includes a cylindrical first part and a second part connected to the first part. The first part abuts against the inflatable adjustment bag. The second part is a threaded rod. The inflatable adjustment bag is cylindrical, and the size of the cross section of the inflatable adjustment bag is exactly the same as the size of the cross section of the first part.

6. The reinforcement structure applied to the bridge-road transition section of high-speed railways in expansive soil areas according to claim 1, characterized in that, The inflatable adjustment package includes an inflatable housing with an inflation port, a laser rangefinder disposed at the center of the bottom of the inflatable housing, and a reflector disposed at the top of the inflatable housing and in the detection direction of the laser rangefinder. The inflatable housing is a cylindrical housing. The laser rangefinder is electrically connected to the controller of the pressure regulator, and the inflation port of the inflatable housing is connected to the inflation component of the pressure regulator.

7. The reinforcement structure applied to the bridge-road transition section of high-speed railways in expansive soil areas according to claim 6, characterized in that, The upper surface of the inflatable adjustment package is flush with the upper surface of the EPS layer, and the lower surface of the inflatable adjustment package is flush with the lower surface of the EPS layer.

8. The reinforcement structure applied to the bridge-road transition section of high-speed railway in expansive soil area according to claim 1, characterized in that, The subgrade transition section includes a cast concrete body formed by casting, multiple groups of foamed concrete groups sandwiched between the cast concrete body and the subgrade, and a plurality of connecting rods spaced along the height direction of the abutment. One end of each connecting rod is connected to the abutment, and the other end sequentially passes through the reserved holes of the cast concrete body and a group of the foamed concrete groups and is inserted into the subgrade. Barbs are provided at the other end of the connecting rod inserted into the subgrade.

9. The reinforcement structure applied to the bridge-road transition section of high-speed railway in expansive soil area according to claim 8, characterized in that, The transition section reinforcement structure further includes a subgrade bed layer covering the subgrade transition section and the side of the subgrade away from the cushion section. From the subgrade bed layer to the cushion section direction, the cast concrete body is in the shape of an inverted right-angled trapezoid with a longer upper side and a shorter lower side.

10. A construction method of the reinforcement structure according to claim 9, characterized in that, It includes the following steps: Step (1), based on the design requirements of the high-speed rail transition section and the on-site geological conditions, determine the quantity, size, and arrangement method of the prestressed screw piles forming the screw pile array; Step (2), provide a plurality of foamed concretes with reserved holes and a plurality of prestressed screw piles. Each prestressed screw pile is prestressed by the pretensioning method using prestressed steel bars and cured to the design strength; Step (3), install the prestressed screw columns according to the arrangement method of the screw pile array, and control the verticality and pile top elevation of the prestressed screw columns to meet the design requirements, and backfill and compact the pile holes with the original soil; Step (4), lay the EPS layer and a plurality of inflatable adjustment packages on the top surface of the expansive soil foundation according to the design requirements, and fill high-pressure gas into the inflatable adjustment packages to control the elevation of the upper surface of the inflatable adjustment package to be consistent with the upper surface of the EPS; Step (5), lay the main body of the cushion on the upper surfaces of the EPS layer and the plurality of inflatable adjustment packages in a preset manner to form a cushion; Step (6), lay a layer of foamed concrete on the top surface of the cushion. When laying, make the reserved holes form a through hole, and pass the connecting rod through the reserved hole to the abutment; Step (7), backfill and compact the subgrade to make the elevation of the subgrade consistent with that of the foamed concrete; Step (8), repeat Step (6) and Step (7), lay the foamed concrete and backfill and compact the subgrade in layers. When the design elevation is met, cast the cast concrete body at one time and cure it to the design strength; finally, lay the subgrade bed layer.

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