Straddle type rack rail fill roadbed system and construction method thereof

Abstract

The invention provides a fill roadbed system of a straddle type rack rail and a construction method of the fill roadbed system. The fill roadbed system is particularly suitable for track line construction under the condition of a large longitudinal slope. The system is composed of a rack rail roadbed structure, a filling structure and an accessory structure. The rack rail roadbed structure comprises joists and pile foundations. The filling structure comprises a platform section, a longitudinal slope filling section, a platform transition section, a road and bridge transition platform section, a road and bridge transition slope section and a back pressure body section. The accessory structure comprises a roadbed surface sealing layer, a slope protection structure, a drainage ditch and a monitoring structure. The construction method comprises the steps of soil body filling, deformation monitoring, toothed rail roadbed structure and back pressure body section construction, accessory structure and toothed rail track construction and the like. According to the method, the rack rail roadbed structure, the filling structure and the accessory structure are sequentially combined, the construction quality and safety of the roadbed under the large longitudinal slope condition can be guaranteed, and the method has the advantages of being good in economical efficiency, small in settlement, good in stability, environmentally friendly, high in safety, reliable in quality and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of track engineering, and specifically to an embankment subgrade system for a straddle-type toothed rail and a construction method thereof. Background Art

[0002] With the vigorous development of rail transit technology, various new types of track systems have emerged on the basis of conventional railway systems and subway systems, such as tram transit systems, medium and low-speed maglev transit systems, suspended monorail systems, straddle-type monorail systems, mountain toothed rail systems, etc. The maximum allowable longitudinal slope of track lines has gradually increased from 3% in railway systems to 12% in mountain toothed rail systems. For sections with a longitudinal slope exceeding 6%, the maximum longitudinal slope section is set in the tunnel section or bridge section, and the maximum longitudinal slope of the subgrade section does not exceed 6%. For track lines with a longitudinal slope exceeding 12%, there are currently no actual application cases in China and there are still a large number of problems with the corresponding technologies.

[0003] The large longitudinal slope of track lines makes great contributions to adapting to mountainous terrain, reducing line length and saving investment. A new type of straddle-type toothed rail system currently in the preliminary research stage can adapt to large longitudinal slope track lines, and this system is generated by combining a straddle-type monorail and a toothed rail. For straddle-type monorails, according to the "Straddle-Type Monorail Traffic Design System" GB50458, the maximum longitudinal slope is only 6% and all are bridge structures, without subgrade or low-lying line structures; for mountain toothed rails, according to the "Technical Specification for Mountain Toothed Rail Rail Transit" DB51T2542, the maximum longitudinal slope can theoretically reach 48%. For cases where the maximum longitudinal slope is greater than 12%, the relevant technical requirements are not clearly defined in the specification. For the Dujiangyan - Siguniang Mountain Toothed Rail Project, which is currently the only actual project using mountain toothed rails, the maximum longitudinal slope of the tunnel section is 12%, and the maximum longitudinal slopes of the bridge section and subgrade section do not exceed 6%.

[0004] According to the previous research results, investigation results and the patent "Straddle-Type Toothed Rail Single Girder, Support Structure and Construction Method Thereof" CN115387168A, it is found that currently, the straddle-type toothed rail structures applicable to longitudinal slopes greater than 12% are all bridge structures, but bridge structures have problems such as high engineering costs and difficult maintenance. Under large longitudinal slope conditions, with large longitudinal loads and steep longitudinal slopes, the conventional subgrade construction method, namely "layered filling along the longitudinal slope", cannot guarantee the compaction degree, compaction uniformity, K30 and other compaction conditions of the soil body, and there are problems such as uneven settlement and poor longitudinal stability. Moreover, various construction machinery is restricted to a certain extent or even cannot be used under large longitudinal slopes. Therefore, the conventional subgrade structure and its construction method can no longer be applied to the straddle-type toothed rail system under large longitudinal slope conditions. In addition, large longitudinal slope track lines are mostly located near mountainous areas or nature reserves, and the environmental protection and water and soil conservation requirements are particularly strict, with a long distance for waste soil transportation and high treatment costs.

[0005] Therefore, there is an urgent need for a straddle-type toothed rail subgrade system and its construction method that are economically viable, have reliable construction quality, small settlement, and good longitudinal stability under large longitudinal slope conditions. Summary of the Invention

[0006] In view of the problems in the existing straddle-type bridge structure form, such as high engineering costs and difficult maintenance, and in view of the problems of difficult subgrade compaction, limited construction, uneven settlement, and poor longitudinal stability under large longitudinal slope conditions, a straddle-type toothed rail subgrade system and its construction method applicable to large longitudinal slope conditions are provided. The structure and method have the advantages of good economy, reliable construction quality, small settlement, good longitudinal stability, and environmental protection.

[0007] The technical solution adopted by the present invention to solve its technical problems is a filled subgrade system for a straddle-type toothed rail, including:

[0008] A toothed rail subgrade structure, including a supporting beam and pile foundations. The supporting beams are arranged at intervals at the expansion joints of the toothed rail track along the direction of the toothed rail track. The supporting beams are sequentially divided into the 1st-level supporting beam, the 2nd-level supporting beam, until the (N - 1)-th level supporting beam and the N-th level supporting beam in the order of the number of supporting beams along the direction of the toothed rail track. One or two pile foundations are arranged at intervals along the length direction of each supporting beam at the bottom of each supporting beam. One or two toothed rail connectors are arranged on the top of each supporting beam and are connected to the toothed rail track structure. A toothed rail bridge structure is arranged behind the N-th level supporting beam.

[0009] A filling structure, including a subgrade filling structure and a filling structure for the road-bridge transition section. The subgrade filling structure includes a platform section, a longitudinal slope filling section, a platform transition section, and a counterweight section.

[0010] The longitudinal slope filling section is the layered filling soil along the direction of the toothed rail track from the center line of the current-level supporting beam to the intersection of the top surface line of the current-level longitudinal slope filling section and the bottom surface line of the next-level supporting beam. The longitudinal slope filling section is divided into the 1st-level longitudinal slope filling section, the 2nd-level longitudinal slope filling section, until the (N - 1)-th level longitudinal slope filling section along the direction of the toothed rail track based on the supporting beam number. The top surface line of the longitudinal slope filling section is parallel to the direction of the toothed rail track and is connected to the top surface of the supporting beam. The platform section is the layered filling soil along the direction of the toothed rail track from the intersection of the top surface line of the upper-level longitudinal slope filling section and the bottom surface line of the current-level supporting beam to the center line of the supporting beam. The platform section is divided into the 2nd-level platform section, until the (N - 1)-th level platform section and the N-th level platform section along the direction of the toothed rail track based on the supporting beam number. The platform transition section is the triangular layered filling soil with a slope no steeper than 1:1 along the direction of the toothed rail track starting from the ground line or from the current-level platform section to the center line of the current-level supporting beam. The platform transition section is divided into the 1st-level platform transition section, the 2nd-level platform transition section, until the (N - 1)-th level platform transition section along the direction of the toothed rail track based on the supporting beam number. The counterweight section is the triangular layered filling soil with a slope no steeper than 1:3 along the direction of the toothed rail track starting from the current-level platform section to the side of the current-level supporting beam.

[0011] The filling structure of the road-bridge transition section includes a road-bridge transition platform section and a road-bridge transition slope section. The road-bridge transition platform section is the layered filled soil within a horizontal distance of not less than 2 m starting from the end point of the Nth platform section along the direction of the rack rail. The road-bridge transition slope section is the layered filled soil with a slope no steeper than 1:1.5 from the end point of the road-bridge transition platform section to the ground line along the direction of the rack rail.

[0012] Ancillary structures include a subgrade surface sealing layer, a slope protection structure, a drainage ditch, and a monitoring structure. The subgrade surface sealing layer is arranged on the top surface of the layered filled soil. The slope protection structure is arranged on both sides of the layered filled soil. The drainage ditch is arranged on the top surface of the foundation soil outside the layered filled soil. The monitoring structure is arranged at the middle position of the top surface of the platform section.

[0013] Furthermore, the bearing beam has a right trapezoidal longitudinal section, and the slope of the top surface of the bearing beam is the same as that of the rack rail. On both sides of the bearing beam are respectively an embankment section and a longitudinal slope filling section.

[0014] A construction method for a filled subgrade system of a straddle-type rack rail includes the following steps:

[0015] S1: Soil filling construction

[0016] S11: After clearing and leveling the ground, accurately set out and position the locations of the bearing beam and pile foundation. Segmentally arrange the bearing beam, platform section, longitudinal slope filling section, and platform transition section along the direction of the rack rail in the order of the number of bearing beams from the 1st level to the Nth level. Divide the bearing beam into the 1st-level bearing beam to the Nth-level bearing beam, the platform transition section into the 1st-level platform transition section to the (N - 1)th-level platform transition section, the longitudinal slope filling section into the 1st-level longitudinal slope filling section to the (N - 1)th-level longitudinal slope filling section, and the platform section into the 2nd-level platform section to the Nth-level platform section;

[0017] S12: Calculate the scope and elevation of the platform section, longitudinal slope filling section, platform transition section, road-bridge transition platform section, and road-bridge transition slope section, and conduct on-site setting out;

[0018] S13: Layer by layer, fill in sequence the 1st-level platform transition section, the 1st-level longitudinal slope filling section, the 2nd-level platform section, the 2nd-level longitudinal slope filling section along the direction of the rack rail until the layered filled soil of the (N - 1)th-level platform section and the (N - 1)th-level longitudinal slope filling section, and finally fill in sequence the layered filled soil of the Nth-level platform section, the road-bridge transition platform section, and the road-bridge transition slope section.

[0019] S14: Each layer of layered filled soil is filled horizontally or with a gentle slope. After each layer of layered filled soil is filled, compact the layered filled soil, and then conduct compaction tests such as K30 and degree of compaction. After passing the tests, fill in the next layer of layered filled soil;

[0020] S15: Repeat S13 and S14 until the top elevation of the layered fill soil reaches the starting elevation of the first - stage longitudinal slope fill section, completing all the fills of the first - stage platform transition section and partial fills of the remaining fill sections.

[0021] S16: Continue to layer - by - layer fill the first - stage longitudinal slope fill section, the second - stage platform section, the second - stage longitudinal slope fill section along the direction of the rack rail, until the layered fill soil of the (N - 1)th - stage platform section and the (N - 1)th - stage longitudinal slope fill section, and finally layer - by - layer fill the layered fill soil of the Nth - stage platform section, the road - bridge transition platform section, and the slope section of the road - bridge transition section.

[0022] S17: Each layer of the layered fill soil is filled using horizontal filling or gentle - slope filling. After each layer of the layered fill soil is filled, compact the layered fill soil, and then conduct compaction tests such as K30 and degree of compaction. After passing the tests, fill the next layer of the layered fill soil;

[0023] S18: Repeat S16 and S17 until the top elevation of the layered fill soil reaches the elevation of the second - stage platform section, completing all the fills of the first - stage longitudinal slope fill section and the second - stage platform section, and partial fills of the remaining fill sections.

[0024] S19: Continue to layer - by - layer fill the second - stage platform transition section, the second - stage longitudinal slope fill section, the third - stage platform section, the third - stage longitudinal slope fill section along the direction of the rack rail, until the layered fill soil of the (N - 1)th - stage platform section and the (N - 1)th - stage longitudinal slope fill section, and finally layer - by - layer fill the layered fill soil of the Nth - stage platform section, the road - bridge transition platform section, and the slope section of the road - bridge transition section.

[0025] S20: According to the methods of S13, S14, S15, S16, S17, and S18, successively complete all the fills of the second - stage platform transition section, the second - stage longitudinal slope fill section, and the third - stage platform section until all the fills of the (N - 1)th - stage platform transition section, the (N - 1)th - stage longitudinal slope fill section, and the Nth - stage platform section are completed;

[0026] S20: Since the top elevation of the Nth - stage platform section is basically the same as the top elevations of the road - bridge transition platform section and the road - bridge transition slope section, when the top elevation of the layered fill soil reaches the Nth - stage platform section, all the fills of the road - bridge transition platform section and the road - bridge transition slope section are also completed.

[0027] S2: Deformation monitoring and deformation evaluation

[0028] S21: Set up monitoring structures at the middle positions of each stage of the platform section to monitor settlement and horizontal displacement;

[0029] S22: After the monitoring time is not less than the design requirements, predict the post - construction settlement of the subgrade based on the existing settlement data;

[0030] S23: When the predicted post-construction settlement is greater than the design requirement, first estimate the settlement observation period, then extend the monitoring time in months. After the monitoring time is reached again, re-estimate the post-construction settlement of the subgrade.

[0031] S24: Repeat the methods of S22 and S23 until the predicted post-construction settlement is less than the design requirement, and then proceed to the next construction process.

[0032] S3: Construction of the rack rail subgrade structure and the counterweight section

[0033] S31: Take each platform section as the drilling rig operation platform. According to the positioning of the bearing beam and the pile foundation, construct the pile foundation under the bearing beam, and temporarily place the soil excavated from the pile foundation on this platform section.

[0034] S32: After the strength of the pile foundation reaches the design requirement, chisel the pile head, excavate the platform transition section and temporarily place the soil on this platform section, and then construct the bearing beam.

[0035] S33: After the strength of the bearing beam reaches the design requirement, fill the soil excavated from the pile foundation and the platform transition section against the bearing beam at a slope no steeper than 1:3 to form a triangular counterweight section.

[0036] S34: Construct the rack rail bridge structure behind the Nth-level bearing beam.

[0037] S4: Construction of the ancillary structure and the rack rail

[0038] S41: Construct the closed layer of the subgrade surface and carry out the closed treatment with plain concrete or masonry rubble.

[0039] S42: Construct the slope protection structure on the side slopes of the soil filled in layers, and construct a connected drainage ditch outside the toe line and outside the road-bridge transition slope section.

[0040] S43: Install one or two rack rail connectors on the top of each bearing beam. Install one rack rail connector for a single-track rack rail line and two rack rail connectors for a double-track rack rail.

[0041] S44: Construct the rack rail above the rack rail connector and connect it to the rack rail connector.

[0042] The beneficial effects of the present invention are as follows:

[0043] 1. A fill subgrade system suitable for a straddle-type rack rail and its construction method of the present invention have the advantages of good economy, small settlement, good stability, environmental protection, high safety, and reliable construction quality.

[0044] 2. A fill subgrade system for straddle-type toothed rails of the present invention not only provides a brand-new general-section straddle subgrade structure for the straddle-type toothed rail system, but also provides a non-contact transition structure with good economy from the general-section straddle-type toothed rail subgrade to the straddle-type toothed rail bridge by setting a road-bridge transition platform section and a slope section of the road-bridge transition section, as opposed to the traditional rigid-contact road-bridge transition section.

[0045] 3. A fill subgrade system for straddle-type toothed rails of the present invention uses the overall toothed rail subgrade structure set on the filling structure as the foundation of the toothed rail, having the advantages of small settlement and uneven settlement; by using the method of combining the toothed rail subgrade structure with the filling structure, it can effectively improve the longitudinal stability and reduce the adverse effects of the longitudinal force on the large longitudinal slope on the toothed rail subgrade structure, having the advantages of good longitudinal stability and good economy.

[0046] 4. A fill subgrade system for straddle-type toothed rails of the present invention uses the form of a segmented, variable-slope filling structure and a special-shaped corbel beam, which well adapts to the requirements of the large longitudinal slope toothed rail, avoids structural conflicts, and cleverly solves the difficulty of hard compaction of the large longitudinal slope subgrade.

[0047] 5. A fill subgrade system for straddle-type toothed rails of the present invention can use waste soil for filling, and uses the excavated waste soil of the corbel beam and pile foundation as the anti-pressure body section, which not only realizes waste-free construction, but also well treats other waste soil, solves the problems of high waste treatment cost and environmental protection of water, and has the advantages of good economy and environmental protection.

[0048] 6. A construction method for a fill subgrade for straddle-type toothed rails of the present invention uses a segmented, variable-slope, horizontal or gentle-slope filling and compaction method to solve the difficulty of compacting the conventional large longitudinal slope subgrade, ensures the compaction quality of the subgrade, effectively reduces the post-construction settlement and improves the slope stability.

[0049] 7. A construction method for a fill subgrade for straddle-type toothed rails of the present invention uses the methods of settlement monitoring and settlement evaluation after filling, which is safe, reliable and has good economy. On the one hand, it ensures the project safety and the post-construction settlement can meet the design requirements, and on the other hand, it can reduce the negative skin friction of the pile foundation, thus achieving the effect of saving the pile foundation investment.

[0050] 8. A fill subgrade system and construction method for straddle-type toothed rails of the present invention well solve the problems of difficult construction or impossible construction of construction machinery such as slag trucks, rollers, bulldozers and drills on large longitudinal slopes by setting a platform section and a longitudinal slope filling section and using the horizontal or gentle-slope filling method, realizing the effective compaction of the subgrade filling under large longitudinal slope conditions, and the construction quality is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic structural diagram of the present invention;

[0052] Figure 2 is Figure 1 a top view of

[0053] Figure 3 is a schematic cross-sectional view at the platform transition section;

[0054] Figures 4 - 7 is a schematic diagram of the construction process of the present invention.

[0055] Reference numerals: 1 - bearing beam; 101 - first-level bearing beam; 102 - second-level bearing beam; 103 - (N - 1)-th level bearing beam; 104 - N-th level bearing beam; 2 - pile foundation; 3 - rack rail track; 4 - rack rail bridge structure; 5 - rack rail track expansion joint; 6 - layered filled soil; 7 - longitudinal slope filling section; 701 - first-level longitudinal slope filling section; 702 - second-level longitudinal slope filling section; 703 - (N - 1)-th level longitudinal slope filling section; 8 - platform section; 801 - second-level platform section; 802 - (N - 1)-th level platform section; 803 - N-th level platform section; 9 - platform transition section; 901 - first-level platform transition section; 902 - second-level platform transition section; 903 - (N - 1)-th level platform transition section; 10 - road-bridge transition platform section; 11 - road-bridge transition slope section; 12 - embankment section; 13 - subgrade surface sealing layer; 14 - slope protection structure; 15 - monitoring structure; 16 - drainage ditch; 17 - rack rail connector; 18 - foundation soil; 19 - ground line; 20 - toe line. Detailed Description of the Invention

[0056] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0057] Referring to Figures 1 to 7 , a fill subgrade system for a straddle-type rack rail includes:

[0058] A rack rail subgrade structure, including a bearing beam 1 and a pile foundation 2. The bearing beam 1 is arranged at intervals at the rack rail track expansion joint 5 along the direction of the rack rail track 3. The bearing beam 1 is sequentially divided into a first-level bearing beam 101, a second-level bearing beam 102, up to a (N - 1)-th level bearing beam 103 and an N-th level bearing beam 104 in the order of the number of bearing beams along the direction of the rack rail track 3. One or two pile foundations 2 are arranged at intervals along the length direction of each bearing beam 1 at the bottom of each bearing beam 1. One or two rack rail connectors 17 are arranged at the top of each bearing beam 1 and are connected to the rack rail track structure 4. A rack rail bridge structure 4 is arranged behind the N-th level bearing beam 104.

[0059] Among them, the bearing beam 1 is a concrete structure with a right trapezoidal longitudinal section, which is prefabricated in a factory or cast in situ. The upper surface of the bearing beam 1 is an inclined surface, and the top surfaces of all the bearing beams 1 are located on the same inclined surface. The slope of the inclined surface is the same as that of the toothed rail track 3 at the expansion joint 5 of the toothed rail track. The center line of the bearing beam 1 coincides with the center line of the filling layer, and the length of the bearing beam 1 is less than the width of the filling layer; the foundation pile 2 is a cast-in-situ concrete structure, and the number of the foundation piles 2 can be one or two. The toothed rail bridge structure 4 includes two opposite bridge piers, and a capping beam is arranged on the top of the bridge piers; toothed rail connectors 17 are fixedly installed on the top of the toothed rail bridge structure 4 and each bearing beam 1, and then the toothed rail track 3 is installed on the toothed rail connectors 17.

[0060] The filling structure includes a subgrade filling structure and a road-bridge transition section filling structure. The subgrade filling structure includes a platform section 8, a longitudinal slope filling section 7, a platform transition section 9 and a counterweight section 12.

[0061] The longitudinal slope filling section 7 is the layered filling soil 6 along the toothed rail track 3 direction from the center line of the current-level bearing beam 1 to the intersection point of the top surface line of the current-level longitudinal slope filling section 7 and the bottom surface line of the next-level bearing beam 1. The longitudinal slope filling section 7 is divided into the first-level longitudinal slope filling section 701, the second-level longitudinal slope filling section 702 along the toothed rail track 3 direction based on the bearing beam number, until the (N - 1)-level longitudinal slope filling section 703. The top surface line of the longitudinal slope filling section 7 is parallel to the toothed rail track 3 direction and is connected to the top surface of the bearing beam 1.

[0062] The platform section 8 is the layered filling soil 6 along the toothed rail track 3 direction from the intersection point of the top surface line of the upper-level longitudinal slope filling section 7 and the bottom surface line of the current-level bearing beam 1 to the center line of the bearing beam 1. The platform section 8 is divided into the second-level platform section 801, until the (N - 1)-level platform section 802 and the N-level platform section 803 along the toothed rail track 3 direction based on the bearing beam number.

[0063] The platform transition section 9 is the triangular layered filling soil 6 with a slope not steeper than 1:1 along the toothed rail track 3 direction starting from the ground line 19 or from the current-level platform section 8 to the center line of the current-level bearing beam 1. The platform transition section 9 is divided into the first-level platform transition section 901, the second-level platform transition section 902 along the toothed rail track 3 direction based on the bearing beam number, until the (N - 1)-level platform transition section 903.

[0064] The counterweight section 12 is the triangular layered filling soil 6 with a slope not steeper than 1:3 along the toothed rail track 3 direction starting from the current-level platform section 8 to the side surface of the current-level bearing beam 1.

[0065] The subgrade filling structure can be filled in layers with waste soil, and the filling can be carried out by horizontal filling or gentle slope filling; the platform transition section 9, the longitudinal slope filling section 7, and the platform section 8 are arranged in sequence. The setting of the platform transition section 9 ensures the stability of the slope near the junction of the longitudinal slope filling section 7 and the platform section 8, and can prevent the collapse of the side of the longitudinal slope filling section 7; the slope of the longitudinal slope filling section 7 is adapted to the longitudinal slope of the line, and the platform section 8 is adapted to the position of the bottom elevation of the bearing beam 1. The position of the platform transition section 9 is determined by determining the position of the platform section 8. The soil generated during the formation of the pile foundation 2 and the excavation of the bearing beam 1 is used to build the anti-pressure body section 12 in front of the bearing beam 1 at a slope not steeper than 1:3 by manual or small mechanical ramming; such an arrangement not only realizes construction without waste soil, but also well disposes of other waste soil, solves the problems of high treatment cost of waste soil and environmental protection of water and soil, has the advantages of good economy and environmental protection, and at the same time the anti-pressure body section 12 can also improve the stability of the bearing beam 1.

[0066] The filling structure of the road and bridge transition section includes a road and bridge transition platform section 10 and a road and bridge transition slope section 11. The road and bridge transition platform section 10 is the layered filling soil 6 within a horizontal distance of not less than 2m starting from the end point of the Nth platform section 803 along the direction of the rack rail 3. The road and bridge transition slope section 11 is the layered filling soil 6 with a slope not steeper than 1:1.5 from the end point of the road and bridge transition platform section 10 to the ground line 19 along the direction of the rack rail 3.

[0067] The ancillary structure includes a subgrade surface sealing layer 13, a slope protection structure 14, a drainage ditch 16 and a monitoring structure 15. The subgrade surface sealing layer 13 is arranged on the top surface of the layered filling soil 6 of the subgrade filling structure. The slope protection structure 14 is arranged on both sides of the layered filling soil 6. The drainage ditch 16 is arranged on the top surface of the foundation soil 18 outside the layered filling soil 6. The monitoring structure 15 is arranged at the middle position of the top surface of the platform section 8;

[0068] The base surface sealing layer 13 is sealed with 0.1m thick plain concrete or 0.2m thick masonry rubble to prevent rainwater from seeping down and reduce the adverse effects on slope stability and settlement. The monitoring structure 15 is a plain concrete column, and the monitoring structure 15 is arranged at the middle position of each platform section 8 to monitor settlement and horizontal displacement. The slope protection structure 14 is arranged on both sides of the layered filling soil 6, and the slope protection structure 14 can adopt grass and shrub slope protection, frame slope protection + plant protection; the drainage ditch 16 is a plain concrete ditch.

[0069] Furthermore, the bearing beam 1 has a right trapezoidal longitudinal section, and the slope of the top surface of the bearing beam 1 is the same as the slope of the rack rail 3 at the expansion joint 5 of the rack rail. The two sides of the bearing beam 1 are respectively the anti-pressure body section 12 and the longitudinal slope filling section 7. On the one hand, this can avoid conflicts between the bearing beam 1 and the rack rail 3, and on the other hand, it can achieve a smooth transition with the longitudinal slope filling section 7.

[0070] A construction method for a filled subgrade system of a straddle-type rack rail, see Figures 4 - 7 , including the following steps:

[0071] S1: Earth filling construction

[0072] S11: After clearing and leveling the ground, accurately set out and position the locations of the tie beams 1 and the pile foundations 2. The tie beams 1, the platform section 8, the longitudinal slope filling section 7, and the platform transition section 9 are arranged in segments from the 1st level to the Nth level in the order of the number of tie beams along the rack rail track 3. The tie beams 1 are divided into the 1st-level tie beam 101 to the Nth-level tie beam 104, the platform transition section 9 is divided into the 1st-level platform transition section 901 to the (N - 1)th-level platform transition section 903, the longitudinal slope filling section 7 is divided into the 1st-level longitudinal slope filling section 701 to the (N - 1)th-level longitudinal slope filling section 703, and the platform section 8 is divided into the 2nd-level platform section 801 to the Nth-level platform section 803.

[0073] S12: Calculate the scope and elevation of the platform section 8, the longitudinal slope filling section 7, the platform transition section 9, the road-bridge transition platform section 10, and the road-bridge transition slope section 11, and conduct on-site setting out.

[0074] S13: Layer by layer, fill in sequence along the rack rail track 3 the 1st-level platform transition section 901, the 1st-level longitudinal slope filling section 701, the 2nd-level platform section 801, the 2nd-level longitudinal slope filling section 702, until the (N - 1)th-level platform section 802 and the (N - 1)th-level longitudinal slope filling section 703 with the layered filling soil 6, and finally fill in sequence the Nth-level platform section 803, the road-bridge transition platform section 10, and the layered filling soil 6 of the road-bridge transition slope section 11.

[0075] S14: For each layer of the layered filling soil 6, adopt horizontal filling or gentle slope filling. After each layer of the layered filling soil 6 is filled, compact the layered filling soil 6, and then conduct compaction tests such as K30 and degree of compaction. After passing the tests, fill in the next layer of the layered filling soil 6.

[0076] S15: Repeat S13 and S14 until the top elevation of the layered filling soil 6 reaches the starting elevation of the 1st-level longitudinal slope filling section 701, completing the filling of the entire 1st-level platform transition section 901 and partial filling of the remaining filling sections.

[0077] S16: Continue to layer by layer, fill in sequence along the rack rail track 3 the 1st-level longitudinal slope filling section 701, the 2nd-level platform section 801, the 2nd-level longitudinal slope filling section 702, until the (N - 1)th-level platform section 802 and the (N - 1)th-level longitudinal slope filling section 703 with the layered filling soil 6, and finally fill in sequence the Nth-level platform section 803, the road-bridge transition platform section 10, and the layered filling soil 6 of the road-bridge transition slope section 11.

[0078] S17: For each layer of the layered filling soil 6, horizontal filling or gentle slope filling is adopted. After each layer of the layered filling soil 6 is filled, the layered filling soil 6 is compacted, and then compaction tests such as K30 and compaction degree are carried out. After passing the tests, the next layer of the layered filling soil 6 is filled.

[0079] S18: Repeat S16 and S17 until the top elevation of the layered filling soil 6 reaches the elevation of the second-level platform section 801, and complete all the filling of the first-level longitudinal slope filling section 701 and the second-level platform section 801, and partial filling of the remaining filling sections.

[0080] S19: Continue to layer and fill the second-level platform transition section 902, the second-level longitudinal slope filling section 702, the third-level platform section, and the third-level longitudinal slope filling section in sequence along the direction of the rack rail 3 until the layered filling soil 6 of the (N - 1)-th level platform section 802 and the (N - 1)-th level longitudinal slope filling section 703. Finally, layer and fill the layered filling soil 6 of the N-th level platform section 803, the road-bridge transition platform section 10, and the road-bridge transition section slope 11 in sequence.

[0081] S20: According to the methods of S13, S14, S15, S16, S17, and S18, complete the second-level platform transition section 902, the second-level longitudinal slope filling section 702, and the third-level platform section in sequence. All filling of the third-level platform section is completed according to the rule until all filling of the (N - 1)-th level platform transition section 903, the (N - 1)-th level longitudinal slope filling section 703, and the N-th level platform section 803 is completed. Since the top elevation of the N-th level platform section 803 is basically the same as the top elevations of the road-bridge transition platform section 10 and the road-bridge transition slope section 11, all filling of the road-bridge transition platform section 10 and the road-bridge transition slope section 11 is completed when the top elevation of the layered filling soil 6 reaches the N-th level platform section 803.

[0082] S2: Deformation monitoring and deformation evaluation

[0083] S21: Set the monitoring structure 15 at the middle position of each platform section 8 to monitor settlement and horizontal displacement.

[0084] S22: After the monitoring time is not less than the design requirement, predict the post-construction settlement of the subgrade based on the existing settlement data.

[0085] S23: When the predicted post-construction settlement is greater than the design requirement, first predict the settlement observation period, and then extend the monitoring time in units of months. After the monitoring time reaches again, re-predict the post-construction settlement of the subgrade.

[0086] S24: Repeat the methods of S22 and S23 until the predicted post-construction settlement is less than the design requirement, and then proceed to the next process.

[0087] S3: Construction of the rack subgrade structure and the anti-pressure body section

[0088] S31: Use each level of platform section 8 as a drilling rig operation platform. According to the positioning of the bearing beam 1 and the pile foundation 2, construct the pile foundation 2 under the bearing beam 1, and temporarily place the soil excavated from the pile foundation 2 on the current level of platform section 8.

[0089] S32: After the strength of the pile foundation 2 reaches the design requirement, chisel off the pile head, excavate the platform transition section 9 and temporarily place the soil on the current level of platform section 8, and then construct the bearing beam 1.

[0090] S33: When the strength of the bearing beam 1 reaches the design requirement, fill the soil excavated from the pile foundation 2 and the soil excavated from the transition section of the platform section 8 against the bearing beam 1 at a slope not steeper than 1:3 to form a triangular counterweight section 12.

[0091] S34: Construct the rack rail bridge structure 4 behind the Nth-level bearing beam 104.

[0092] S4: Construction of auxiliary structures and rack rail tracks

[0093] S41: Construct the subgrade surface sealing layer 13 and carry out sealing treatment with plain concrete or masonry rubble.

[0094] S42: Construct the slope protection structure 14 on the side slopes of both sides of the layered filled soil 6, and construct a connected drainage ditch 16 outside the toe line 20 and outside the road-bridge transition slope section 11.

[0095] S43: Install 1 or 2 rack rail connectors 17 on the top of each bearing beam 1. Install 1 rack rail connector 17 on the single-track rack rail track 3 line, and install 2 rack rail connectors 17 on the double-track rack rail track 3.

[0096] S44: Construct the rack rail track 3 above the rack rail connector 17 and connect it to the rack rail connector 17.

[0097] Embodiment

[0098] The line length is 60m, the line longitudinal slope is 20%, a double-track rack rail structure is adopted, and the horizontal distance between the two rack rails is 3.5m. The height of the subgrade filling structure is 2 - 12m, the large mileage end is connected to the bridge structure, and the small mileage is connected to the cut subgrade. The width of the subgrade filling structure is 12m, the width of the bearing beam is 6m, and the width of the shoulders on both sides is 3m; the center height of the trapezoidal structure of the bearing beam is 2m, a single-pile structure is adopted, the pile diameter is 1.25m, the pile length is 10 - 35m, the span is 20m, and the distance between the bearing beam at the large mileage end and the road-bridge transition section is 2.0m.

[0099] The slope ratio for the longitudinal slope filling section is 1:1.5, the slope ratio for the road-bridge transition slope section is 1:1.5, the slope ratio for the platform transition section is 1:1, the slope ratio for the anti-pressure body is 1:3. The slope protection structure for the slope adopts grass-planting and irrigation slope protection, and the drainage ditch adopts plain concrete ditch. The transportation distance for the waste soil is 30 km, and the filling soil uses the waste soil. After adopting this system and method, the investment for the subgrade including the compaction of the filled soil is about 770,000 yuan, which can solve about 12,000 cubic meters of waste soil and save about 470,000 yuan for the transportation and protection costs of the waste soil. Under the same conditions, if all bridge structures are adopted, the investment is about 670,000 yuan. Adding the transportation and protection costs of the waste soil, compared with the bridge structure, the total investment is saved by 570,000 yuan.

[0100] The embodiments of this specific implementation manner are all preferred embodiments of the present invention, and do not limit the protection scope of the present invention accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A filled subgrade system for a straddle-type toothed rail, characterized in that: Comprising: A rack rail subgrade structure, including a bearing beam (1) and a pile foundation (2), the bearing beams (1) are arranged at intervals at the expansion joints (5) of the rack rail track (3) along the direction of the rack rail track, the bearing beams (1) are successively divided into the first-stage bearing beam (101), the second-stage bearing beam (102), until the (N - 1)-stage bearing beam (103) and the N-stage bearing beam (104) in order according to the number of bearing beams along the direction of the rack rail track (3), one or two pile foundations (2) are arranged at intervals along the length direction of each bearing beam (1) at the bottom of each bearing beam (1), one or two rack rail connectors (17) are arranged at the top of each bearing beam (1) and are connected to the rack rail track structure (3), and a rack rail bridge structure (4) is arranged behind the N-stage bearing beam (104); where N is a positive integer ≥ 3; A filling structure, including a subgrade filling structure and a filling structure for the road - bridge transition section, the subgrade filling structure includes a platform section (8), a longitudinal slope filling section (7), a platform transition section (9) and a counter - pressure body section (12); The longitudinal slope filling section (7) is the layered filling soil along the direction of the rack rail track (3) from the center line of the current - stage bearing beam (1) to the intersection point of the top surface line of the current - stage longitudinal slope filling section (7) and the bottom surface line of the next - stage bearing beam (1), the longitudinal slope filling section (7) is divided into the first - stage longitudinal slope filling section (701), the second - stage longitudinal slope filling section (702), until the (N - 1)-stage longitudinal slope filling section (703) along the direction of the rack rail track (3) based on the bearing beam numbering, and the top surface line of the longitudinal slope filling section (7) is parallel to the direction of the rack rail track (3) and is connected to the top surface of the bearing beam (1); where N is a positive integer ≥ 3; The platform section (8) is the layered filling soil along the direction of the rack rail track (3) from the intersection point of the top surface line of the upper - stage longitudinal slope filling section (7) and the bottom surface line of the current - stage bearing beam (1) to the center line of the bearing beam (1), the platform section (8) is divided into the second - stage platform section (801), until the (N - 1)-stage platform section (802) and the N - stage platform section (803) along the direction of the rack rail track (3) based on the bearing beam numbering; where N is a positive integer ≥ 3; The platform transition section (9) is the triangular layered filling soil with a slope not steeper than 1:1 along the direction of the rack rail track (3) starting from the ground line (19) or from the current - stage platform section (8) to the center line of the current - stage bearing beam (1), the platform transition section (9) is divided into the first - stage platform transition section (901), the second - stage platform transition section (902), until the (N - 1)-stage platform transition section (903) along the direction of the rack rail track (3) based on the bearing beam numbering; where N is a positive integer ≥ 3; The counter - pressure body section (12) is the triangular layered filling soil (6) with a slope not steeper than 1:3 along the direction of the rack rail track (3) starting from the current - stage platform section (8) to the side surface of the current - stage bearing beam (1); The filling structure of the road-bridge transition section includes a road-bridge transition platform section (10) and a road-bridge transition slope section (11). The road-bridge transition platform section (10) is the layered filling soil (6) within a horizontal distance of not less than 2 m starting from the end of the Nth platform section (803) along the direction of the rack rail (3). The road-bridge transition slope section (11) is the layered filling soil (6) with a slope not steeper than 1:1.5 between the end of the road-bridge transition platform section (10) and the ground line (19) along the direction of the rack rail (3). The accessory structure includes a subgrade surface sealing layer (13), a slope protection structure (14), a drainage ditch (16), and a monitoring structure (15). The subgrade surface sealing layer (13) is arranged on the top surface of the layered filling soil (6). The slope protection structure (14) is arranged on both sides of the layered filling soil (6). The drainage ditch (16) is arranged on the top surface of the foundation soil (18) outside the layered filling soil (6). The monitoring structure (15) is arranged at the middle position of the top surface of the platform section (8).

2. The embankment subgrade system of a straddle-type rack rail according to claim 1, characterized in that: The supporting beam (1) has a right trapezoidal longitudinal section, and the slope of the top surface of the supporting beam (1) is the same as that of the rack rail (3). On both sides of the supporting beam (1), there are respectively a backpressure body section (12) and a longitudinal slope filling section (7).

3. Construction method of a filled subgrade system for a straddle-type rack rail, characterized in that: It includes the following steps: S1: Soil filling construction S11: After clearing and leveling the ground surface, accurately lay out and position the positions of the supporting beam (1) and the pile foundation (2). The supporting beam (1), the platform section (8), the longitudinal slope filling section (7), and the platform transition section (9) are arranged in segments along the direction of the rack rail (3) in the order of the number of supporting beams from the 1st level to the Nth level. The supporting beam (1) is divided into the 1st-level supporting beam (101) to the Nth-level supporting beam (104), the platform transition section (9) is divided into the 1st-level platform transition section (901) to the (N - 1)th-level platform transition section (903), the longitudinal slope filling section (7) is divided into the 1st-level longitudinal slope filling section (701) to the (N - 1)th-level longitudinal slope filling section (703), and the platform section (8) is divided into the 2nd-level platform section (801) to the Nth-level platform section (803). S12: Calculate the scope and elevation of the platform section (8), the longitudinal slope filling section (7), the platform transition section (9), the road-bridge transition platform section (10), and the road-bridge transition slope section (11), and conduct on-site layout. S13: Layer by layer, fill the 1st-level platform transition section (901), the 1st-level longitudinal slope filling section (701), the 2nd-level platform section (801), the 2nd-level longitudinal slope filling section (702) along the direction of the rack rail (3) until the layered filling soil (6) of the (N - 1)th-level platform section (802) and the (N - 1)th-level longitudinal slope filling section (703), and finally fill the layered filling soil (6) of the Nth-level platform section (803), the road-bridge transition platform section (10), and the road-bridge transition slope section (11) in sequence. S14: Each layer of the layered filling soil (6) is filled horizontally or with a gentle slope. After each layer of the layered filling soil (6) is filled, compact the layered filling soil (6), and then conduct compaction tests such as K30 and degree of compaction. After passing the tests, fill the next layer of the layered filling soil (6). S15: Repeat S13 and S14 until the top elevation of the layered fill soil (6) reaches the starting elevation of the first - stage longitudinal slope fill section (701), completing all the fill of the first - stage platform transition section (901) and part of the fill of the remaining fill sections; S16: Continue to layer - by - layer fill the first - stage longitudinal slope fill section (701), the second - stage platform section (801), the second - stage longitudinal slope fill section (702) along the direction of the rack rail (3) in sequence until the layered fill soil (6) of the (N - 1)th - stage platform section (802) and the (N - 1)th - stage longitudinal slope fill section (703), and finally layer - by - layer fill the layered fill soil (6) of the Nth - stage platform section (803), the road - bridge transition platform section (10) and the road - bridge transition section slope (11) in sequence; S17: Each layer of the layered fill soil (6) is filled horizontally or with a gentle slope. After each layer of the layered fill soil (6) is filled, the layered fill soil (6) is compacted, and then compaction tests such as K30 and compaction degree are carried out. After passing the tests, the next layer of the layered fill soil (6) is filled; S18: Repeat S16 and S17 until the top elevation of the layered fill soil (6) reaches the elevation of the second - stage platform section (801), completing all the fill of the first - stage longitudinal slope fill section (701) and the second - stage platform section (801) and part of the fill of the remaining fill sections; S19: Continue to layer - by - layer fill the second - stage platform transition section (902), the second - stage longitudinal slope fill section (702), the third - stage platform section, the third - stage longitudinal slope fill section along the direction of the rack rail (3) in sequence until the layered fill soil (6) of the (N - 1)th - stage platform section (802) and the (N - 1)th - stage longitudinal slope fill section (703), and finally layer - by - layer fill the layered fill soil (6) of the Nth - stage platform section (803), the road - bridge transition platform section (10) and the road - bridge transition section slope (11) in sequence; S20: According to the methods of S13, S14, S15, S16, S17 and S18, complete all the fill of the second - stage platform transition section (902), the second - stage longitudinal slope fill section (702), the third - stage platform section in sequence until all the fill of the (N - 1)th - stage platform transition section (903), the (N - 1)th - stage longitudinal slope fill section (703) and the Nth - stage platform section (803) is completed; Since the top elevation of the Nth - stage platform section (803) is basically the same as the top elevations of the road - bridge transition platform section (10) and the road - bridge transition slope section (11), when the top elevation of the layered fill soil (6) reaches the Nth - stage platform section (803), all the fill of the road - bridge transition platform section (10) and the road - bridge transition slope section (11) is also completed; S2: Deformation monitoring and deformation evaluation S21: Set up a monitoring structure (15) at the middle position of each stage of the platform section (8) to monitor settlement and horizontal displacement; S22: After the monitoring time is not less than the design requirement, predict the post - construction settlement of the subgrade based on the existing settlement data; S23: When the predicted post - construction settlement is greater than the design requirement, first predict the settlement observation period, then extend the monitoring time in months. After the monitoring time reaches again, re - predict the post - construction settlement of the subgrade; S24: Repeat the methods of S22 and S23 until the predicted post-construction settlement is less than the design requirement, and then proceed to the next process; S3: Construction of the rack subgrade structure and the counterweight section S31: Use each platform section (8) as a drilling rig operation platform. According to the positioning of the bearing beam (1) and the pile foundation (2), construct the pile foundation (2) under the bearing beam (1), and temporarily place the soil excavated from the pile foundation (2) on the current platform section (8); S32: After the strength of the pile foundation (2) reaches the design requirement, chisel the pile head, excavate the platform transition section (9) and temporarily place the soil on the current platform section (8), and then construct the bearing beam (1); S33: After the strength of the bearing beam (1) reaches the design requirement, fill the soil excavated from the pile foundation (2) and the soil excavated from the platform transition section (9) against the bearing beam (1) at a slope not steeper than 1:3 to form a triangular counterweight section (12); S34: Construct the rack bridge structure behind the Nth-level bearing beam (104); S4: Construction of the accessory structure and the rack track S41: Construct the roadbed surface sealing layer (13) and perform the sealing treatment with plain concrete or rubble masonry; S42: Construct the slope protection structure (14) on the side slopes of the layered filled soil (6), and construct the connected drainage ditch (16) outside the toe line (20) and outside the road-bridge transition ramp section (11); S43: Install 1 or 2 rack connectors (17) on the top of each bearing beam (1). Install 1 rack connector (17) for the single-track rack track line and install 2 rack connectors (17) for the double-track rack track; S44: Above the rack connector (17), construct the rack track (3) and connect it to the rack connector (17).

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