High-speed railway soft rock deep cutting embankment long-term deformation blocking structure and design method

Abstract

This invention discloses a long-term deformation barrier structure for subgrade in soft rock deep cuts of high-speed railways, including flexible barrier structures arranged longitudinally along both sides of the subgrade. The flexible barrier structure is composed of a flexible composite material filled in a deep trench excavated in the foundation rock mass. The flexible composite material is a mixture of polystyrene (EPS) foam particles, waste tire rubber particles, and polyurethane resin (PU). Polyurethane resin (PU) is a binder that can effectively bind the polystyrene (EPS) foam particles and waste tire rubber particles into a composite material with good compressive and tensile strength. It is also a waterproof material that can prevent groundwater infiltration and form a water-stop curtain. The polystyrene (EPS) foam particles serve as the coarse aggregate of the flexible composite material.

Description

Technical Field

[0001] This invention belongs to the field of roadbed engineering technology, specifically relating to the long-term deformation barrier structure and design method of roadbed in soft rock deep cuts for high-speed railways. Background Technology

[0002] With the construction of my country's high-speed railway network, a large number of lines have already traversed soft rock areas, and more lines will continue to do so, particularly in the southwestern region where numerous deep-cut subgrade projects have been built or are planned in the red bed formations. After deep-cut excavation, changes in the stress field, surface water runoff, and groundwater environment alter the physical and mechanical properties of the underlying soft rock over time. Within a certain depth range, the rock mass undergoes water absorption, expansion, and creep deformation, resulting in slow but continuous horizontal and vertical camber deformation of the subgrade during its design and operational period, seriously threatening train operation safety. Furthermore, high-speed railway ballastless tracks have only a 4mm adjustment space for both vertical camber and horizontal deformation. The long-term horizontal and vertical camber defects caused by the time-dependent deformation of soft rock foundations are difficult to treat, posing significant challenges to line operation and maintenance. Simultaneously, many deep-cut subgrade projects in soft rock areas face the same risk of these defects, severely impacting the construction, operation, and maintenance of my country's high-speed railways. Currently, there are no long-term spatial deformation control measures applicable to both existing and newly constructed soft-rock deep-cut subgrades. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned problems and provide a long-term deformation barrier structure and design method for the subgrade of soft rock deep road cuts in high-speed railways that can effectively block the secondary stress field of the base rock mass and the seepage path of groundwater, while also providing space for the time-dependent deformation of the rock mass.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is: a long-term deformation barrier structure for the subgrade of a high-speed railway in soft rock deep cuts, comprising flexible barrier structures arranged longitudinally along both sides of the subgrade. The flexible barrier structure is composed of a flexible composite material filled in a deep trench excavated in the foundation rock mass. The flexible composite material is a mixture of polystyrene (EPS) foam particles, waste tire rubber particles, and polyurethane resin (PU). Polyurethane resin (PU) is a binder that can effectively bind the polystyrene (EPS) foam particles and waste tire rubber particles into a composite material with good compressive and tensile strength. It is also a waterproof material that can prevent groundwater infiltration and form a water-stop curtain. The polystyrene (EPS) foam particles serve as the coarse aggregate of the flexible composite material.

[0005] Furthermore, the flexible composite filling material is characterized by having a main component with a density of 20 kg / m³. 3It is a mixture of polystyrene (EPS) foam particles, 20-mesh waste tire rubber particles and polyurethane resin (PU), in which EPS foam particles account for about 65-75%, waste tire rubber fragments account for about 20-30%, and polyurethane resin (PU) accounts for 5-10%.

[0006] The present invention also discloses a design method for a long-term deformation barrier structure for the subgrade of a high-speed railway in soft rock deep cuts, which further includes the following steps:

[0007] S1. Determination of the morphology of deep trenches for long-term deformation barrier structure of roadbed in soft rock deep cut;

[0008] S2. Determination of the depth h of the deep trench for the long-term deformation barrier structure of the subgrade in soft rock deep road cut;

[0009] S3. Determination of the width b of the deep trench of the long-term deformation barrier structure of the subgrade in soft rock deep road cut;

[0010] S4. Determination of the longitudinal length l of the deep trench along the line for the long-term deformation barrier structure of the subgrade in soft rock deep cut;

[0011] S5. Determination of the net spacing 'a' of deep trenches in soft rock deep roadbed long-term deformation barrier structures.

[0012] Furthermore, in step S1, a grooving machine is used to cut the groove, and the overall shape of the groove is a cuboid with rounded bottom corners.

[0013] Furthermore, in step S2, the depth h is determined by comprehensive calculation based on the local atmospheric influence depth, annual groundwater level fluctuation, and long-term deformation characteristics of the foundation rock mass within the design service life of the deep road cut;

[0014] Specifically, it includes the following sub-steps:

[0015] S21. Indoor Rock Mechanics Tests: Field drilling and sampling were conducted, and conventional triaxial compression tests were performed on the sampled rock cores indoors to obtain the rock's elastic modulus E, cohesion c, and internal friction angle. Creep tests were conducted on sampled rock cores. The creep test data were fitted using the Burgers model to obtain the rheological parameters of the rock (deformation modulus k, viscosity coefficient η):

[0016]

[0017] In the formula, σ0 is the axial loading pressure of the test, in MPa; k M η M k K η K t represents the fitting parameters for the rheological model; t represents time in hours.

[0018] Time-dependent expansion and deformation tests were conducted on rock cores sampled within the depth range of the atmospheric influence layer to obtain the expansion parameters N and λ.

[0019] ε(t)=N(1-e -λt (2)

[0020] In the formula, N and λ are the expansion parameters obtained from indoor tests, and t is the design service life of the subgrade;

[0021] S22. Three-dimensional numerical simulation calculation: A three-dimensional geological model of the roadbed is established using a finite element program. A viscoelastic-plastic constitutive model is adopted, and the rock physical and mechanical parameters obtained from the above experiments are input. First, elastoplastic calculation is performed to obtain the elastoplastic stress field (horizontal stress σ) of the rock mass below the roadbed after excavation. x and vertical stress σ z Distribution with depth); then, rheological calculations are performed over the design life to obtain the long-term rheological stress field (horizontal stress σ) of the rock mass below the roadbed. cx and vertical stress σ cz Distribution with depth and variation over time;

[0022] S23. Determine the depth of the excavation trench:

[0023] With elastic-plastic stress σ x =σ z Corresponding depth h1;

[0024] The rheological stress σ within the design life cx =σ cz Corresponding to the maximum depth h2;

[0025] The depth of the atmospheric influence layer of the rock mass within the design life is h3;

[0026] The width of the roadbed in the deep cut is 0.4 times h4 = 0.4B;

[0027] Determine the depth of the excavation trench:

[0028] h = max(h1, h2, h3, h4). (3)

[0029] Further, in step S3, the width is determined based on the sum of the horizontal creep deformation b1 caused by stress concentration at the toe of the adjacent slope and the lateral expansion deformation b2 of the roadbed. The horizontal creep deformation b1 is taken as the horizontal deformation at the toe of the deep trench within the design life calculated in the three-dimensional numerical simulation. The lateral expansion deformation b2 of the roadbed is calculated using the following formula based on the expansion parameters obtained from indoor time-dependent expansion tests:

[0030]

[0031] In the formula, B is the roadbed width, N and λ are the expansion parameters obtained from indoor tests, and t is the design service life of the roadbed;

[0032] Considering the safety factor K, and for ease of construction, the width of the deep trench should not be less than 0.15m and not more than 0.3m, it is calculated using the following formula:

[0033] When b1+b2≤0.15, take b=0.15m; (5)

[0034] When 0.15≤b1+b2≤0.30, take b=b1+b2 (6)

[0035] When b1+b2≥0.30, take b=0.30m. (7)

[0036] Furthermore, in step S4, the length l of a single deformable barrier structure deep groove can be 1.0-1.2 times its depth.

[0037] Furthermore, in step S5, the net spacing length a can be taken as 0.2-0.4 times the length of the deep trench, i.e. a = (0.2~0.4)l. A larger value is taken when the rock mass strength is low, and a smaller value is taken when the rock mass strength is high.

[0038] The beneficial effects of this invention are:

[0039] 1. The long-term deformation isolation structure for subgrade in soft rock deep cuts of high-speed railway provided by the present invention can effectively release the long-term vertical heave and horizontal deformation of the subgrade caused by stress concentration at the toe of the slope after deep cut excavation, and meet the requirements of high-speed railway for line smoothness.

[0040] 2. The flexible composite material used in this invention is a mixture of polystyrene (EPS) foam particles, waste tire rubber particles and polyurethane resin (PU). On the one hand, the stiffness of this composite material is much smaller than that of the roadbed rock mass. It can transfer the horizontal deformation of the slope and roadbed rock mass caused by rheology and expansion through its strong deformation capacity. On the other hand, this flexible composite material has a good water-proof effect, which can prevent groundwater from seeping into the roadbed rock mass from the road cut slope and effectively prevent the roadbed rock mass from absorbing water and expanding and deforming.

[0041] 3. The present invention adopts the form of intermittent arrangement of deep trenches, and the rock mass at the separated parts can still play a supporting role for the roadbed rock mass, avoiding uneven settlement and deformation of the roadbed under long-term train load.

[0042] 4. The long-term deformation barrier structure for deep rock roadbeds in high-speed railways is easy and flexible to construct. It can be used for new roadbed projects, implemented during the deep cutting excavation and roadbed construction process, and is also applicable to existing roadbeds. For roadbeds with long-term excessive deformation risk, it can be constructed quickly without affecting the operation of the line, thereby reducing the risk of long-term deformation of the roadbed. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the overall plan layout of the roadbed for the long-term deformation barrier structure of the roadbed in soft rock deep cut of high-speed railway according to the present invention;

[0044] Figure 2 This is the present invention. Figure 1 Enlarged schematic diagram of the structure within the central box;

[0045] Figure 3 This is a cross-sectional view of the subgrade AA of the long-term deformation barrier structure for the subgrade of the high-speed railway in soft rock deep cuts, as described in this invention.

[0046] Figure 4 This is a cross-sectional view of the subgrade BB of the long-term deformation barrier structure for the subgrade in soft rock deep cuts of high-speed railways according to the present invention;

[0047] Figure 5 This is a CC cross-section of the subgrade of the long-term deformation barrier structure for the subgrade in soft rock deep cuts of high-speed railways according to the present invention;

[0048] Figure 6 This is a schematic diagram of the excavation trench structure for the long-term deformation barrier structure of the subgrade in soft rock deep cuts of high-speed railways according to the present invention.

[0049] Explanation of reference numerals in the attached drawings: 1. Deep road cut slope; 2. Deep road cut slope grading platform; 3. Ballastless track; 4. Deep road cut drainage ditch; 11. Excavated slope; 12. Track pier; 13. Track slab; 14. Waterproof membrane; 15. Deep trench; 16. Crushed stone roadbed; 17. Rubber mortar vibration damping layer; 18. Track base plate. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0051] like Figures 1 to 6 As shown, the long-term deformation barrier structure for high-speed railway soft rock deep cutting subgrade provided by the present invention includes flexible barrier structures arranged longitudinally along both sides of the subgrade. The flexible barrier structure is composed of a flexible composite material filled in a deep trench excavated in the foundation rock mass. The flexible composite material is a mixture of polystyrene (EPS) foam particles, waste tire rubber particles and polyurethane resin (PU). Polyurethane resin (PU) is a binder that can effectively bind the polystyrene (EPS) foam particles and waste tire rubber particles into a composite material with good compressive and tensile strength. It is also a waterproof material that can prevent groundwater infiltration and form a water-stop curtain. The polystyrene (EPS) foam particles serve as the coarse aggregate of the flexible composite material.

[0052] In this embodiment, polyurethane resin (PU) is a flexible composite material and a bonding material that can effectively bond polystyrene (EPS) foam particles and waste tire rubber particles into a composite material with good compressive and tensile strength. It is also a waterproof material that can prevent groundwater from seeping in and form a water-stop curtain.

[0053] Polystyrene (EPS) is characterized by low water absorption, light weight, and high mechanical strength, and it also has good compression deformation characteristics, providing large deformation performance for flexible composite materials.

[0054] Waste tire rubber granules, as fine aggregates in flexible composite materials, also have good compression deformation characteristics, and make full use of waste materials, are inexpensive, and are low-carbon and environmentally friendly.

[0055] The main components of the flexible composite filling material are composed of materials with a density of 20 kg / m³. 3 It is a mixture of polystyrene (EPS) foam particles, 20-mesh waste tire rubber particles and polyurethane resin (PU), in which EPS foam particles account for about 65-75%, waste tire rubber fragments account for about 20-30%, and polyurethane resin (PU) accounts for 5-10%.

[0056] Flexible composite materials have physical and mechanical properties such as low density, high strength, and large deformation. They can effectively block the seepage path of groundwater and provide space for the compression deformation of rock masses. At the same time, they are inexpensive and easy to construct.

[0057] The spaced flexible barrier structures effectively cut off groundwater seepage into the basement rock mass, preventing it from absorbing water and causing time-related expansion and deformation. Simultaneously, the spaced flexible barrier structures on both sides of the roadbed separate the roadbed rock mass from the slope. The concentrated stress at the slope toe is released through the large deformation of the flexible composite material, no longer acting on the basement rock mass, thus blocking the stress transmission path and effectively preventing creep deformation of the basement rock mass. By blocking groundwater and stress transmission paths, the expansion and creep deformation of the basement rock mass are prevented, ultimately achieving the goal of preventing long-term deformation of the roadbed. The flexible barrier composite material has good durability, high strength, and large deformation capacity, and is convenient for on-site grouting construction. It can be used for the treatment of existing damaged roadbeds and for disaster prevention of newly constructed roadbeds. The flexible barrier structures, spaced apart on both sides of the roadbed, block groundwater seepage channels and stress transmission paths while ensuring the stability of the roadbed, and the structure is easy to maintain.

[0058] This invention also discloses a design method for a long-term deformation barrier structure for the subgrade of a high-speed railway in soft rock deep cuts, comprising the following steps:

[0059] S1. Determination of the morphology of deep trenches for long-term deformation barrier structure of roadbed in soft rock deep cut.

[0060] In step S1, a grooving machine is used to cut the groove. The groove is generally rectangular with rounded bottom corners. Figure 6 As shown.

[0061] A three-dimensional geological model of deep road cut excavation was established. The cohesion, internal friction angle, bulk modulus, and rheological parameters of the base mudstone were input. Elastoplastic simulation analysis of the roadbed excavation rock mass and rheological analysis for a design service life of 100 years were performed to obtain the elastoplastic stress state σ of the base. cx and σ cz σ, the rheological stress state within the design service life cx and σ cz , and the cumulative creep deformation amount b1 in the horizontal direction at the toe of the slope.

[0062] The roadbed of the high-speed railway is excavated from both sides of soft rock in a deep cutting. The base rock is mudstone, which has low strength, large deformation, rheological properties, and a certain degree of swelling after absorbing water.

[0063] S2. Determination of the depth h of the deep trench for the long-term deformation barrier structure of the subgrade in soft rock deep road cut.

[0064] In step S2, the depth h is determined by comprehensive calculation based on the local atmospheric influence depth, annual groundwater level fluctuation, and long-term deformation characteristics of the foundation rock mass within the design service life of the deep road cut;

[0065] Specifically, it includes the following sub-steps:

[0066] S21. Indoor Rock Mechanics Tests: Field drilling and sampling were conducted, and conventional triaxial compression tests were performed on the sampled rock cores indoors to obtain the rock's elastic modulus E, cohesion c, and internal friction angle. Creep tests were conducted on sampled rock cores. The creep test data were fitted using the Burgers model to obtain the rheological parameters of the rock (deformation modulus k, viscosity coefficient η):

[0067]

[0068] In the formula, σ0 is the axial loading pressure of the test, in MPa; k M η M k K η K t represents the fitting parameters for the rheological model; t represents time in hours.

[0069] Time-dependent expansion and deformation tests were conducted on rock cores sampled within the depth range of the atmospheric influence layer to obtain the expansion parameters N and λ.

[0070] ε(t)=N(1-e -λt (2)

[0071] In the formula, N and λ are the expansion parameters obtained from indoor tests, and t is the design service life of the subgrade.

[0072] Laboratory tests on borehole cores yielded a cohesion of c = 1.98 MPa for the basement mudstone and an internal friction angle of [missing value]. The bulk modulus K = 0.61 GPa, and the rheological parameters are k K =37.0MPa, k M =26.0 GPa, η K =0.6 GPa·d, η M =0.5 GPa·d; Rock mass swelling parameters: N = 0.021, λ = 0.07y -1 The width of the roadbed excavation in the deep cut is B = 20.0m.

[0073] S22. Three-dimensional numerical simulation calculation: A three-dimensional geological model of the roadbed is established using a finite element program. A viscoelastic-plastic constitutive model is adopted, and the rock physical and mechanical parameters obtained from the above experiments are input. First, elastoplastic calculation is performed to obtain the elastoplastic stress field (horizontal stress σ) of the rock mass below the roadbed after excavation. x and vertical stress σ z Distribution with depth); then, rheological calculations are performed over the design life to obtain the long-term rheological stress field (horizontal stress σ) of the rock mass below the roadbed. cx and vertical stress σ cz Distribution with depth and variation over time.

[0074] S23. Determine the depth of the excavation trench:

[0075] With elastic-plastic stress σ x =σ z The corresponding depth is h1.

[0076] The rheological stress σ within the design life cx =σ cz The corresponding maximum depth is h2.

[0077] The depth h3 of the atmospheric influence layer of the rock mass within the design life.

[0078] The width of the roadbed in the deep cut is 0.4 times h4 = 0.4B.

[0079] Determine the depth of the excavation trench:

[0080] h = max(h1, h2, h3, h4). (3)

[0081] Obtain the base stress state σ under elastoplastic conditions x =σ z Corresponding depth h1 = 10.0 m; Rheological stress σ within the design life. cx =σ czThe corresponding maximum depth h2 = 20.0m; the depth of the atmospheric influence layer of the rock mass within the design life is taken as h3 = 5.0m based on regional experience; the width of the deep cut roadbed B = 20.0m, then h4 = 0.4 × 20 = 8.0m. The excavation depth h is determined by equation (3):

[0082] h = max(h1, h2, h3, h4) = 20.0m, and h = 20.0m ≥ h3 = 5.0m satisfies the requirements.

[0083] S3. Determination of the width b of the deep trench of the long-term deformation barrier structure for soft rock deep roadbed.

[0084] In step S3, this width is determined by the sum of the horizontal creep deformation b1 caused by stress concentration at the toe of the adjacent slope and the lateral expansion deformation b2 of the subgrade. The horizontal creep deformation b1 is taken as the horizontal deformation at the toe of the deep trench within the design life calculated in the three-dimensional numerical simulation. The lateral expansion deformation b2 of the subgrade is calculated using the following formula based on the expansion parameters obtained from the indoor time-dependent expansion test:

[0085]

[0086] In the formula, B is the roadbed width, N and λ are the expansion parameters obtained from indoor tests, and t is the design service life of the roadbed;

[0087] Considering the safety factor K, and for ease of construction, the width of the deep trench should not be less than 0.15m and not more than 0.3m, it is calculated using the following formula:

[0088] When b1+b2≤0.15, take b=0.15m; (5)

[0089] When 0.15≤b1+b2≤0.30, take b=b1+b2 (6)

[0090] When b1+b2≥0.30, take b=0.30m. (7)

[0091] In this embodiment, according to the rheological calculation in formula (1), the horizontal creep deformation b1 caused by stress concentration at the toe of the adjacent slope is 0.100 mm; b2 is determined by formula (4): Then b1 + b2 = 0.100 + 0.052 = 0.152m, and the width b of the excavation trench is determined by equation (6):

[0092] b=b1+b2=0.100+0.052=0.152m.

[0093] S4. Determination of the longitudinal length l of the deep trench along the line for the long-term deformation barrier structure of the subgrade in soft rock deep cut.

[0094] In step S4, the length l of a single deformable barrier structure deep groove can be 1.0-1.2 times its depth. In this embodiment, the length l is taken as 1.0 times the groove depth h, that is, l = h = 20.0 m.

[0095] S5. Determination of the net spacing 'a' of deep trenches in soft rock deep roadbed long-term deformation barrier structures.

[0096] In step S5, the net spacing length a can be taken as 0.2-0.4 times the length of the deep trench, i.e. a = (0.2~0.4)l. A larger value is taken when the rock mass strength is low and a smaller value is taken when the rock mass strength is high.

[0097] In this embodiment, since the roadbed base rock mass in the engineering area is mudstone, which has large deformation, 'a' is taken as 0.4 times the length of the deep trench, that is, a = 0.4l = 0.4 × 20.0 = 8.0m.

[0098] The present invention also discloses a construction method for forming a long-term deformation barrier structure for the subgrade of a high-speed railway in soft rock deep cuttings, comprising the following steps:

[0099] S6. For newly constructed roadbeds, the following sub-steps are included:

[0100] S61, graded excavation of roadbed slopes to design elevation.

[0101] like Figure 1 and Figure 2 As shown in the figure, the ballastless track 3 is located in the middle of the deep road cut slope 1, and the deep road cut drainage ditches 4 are provided on both sides of the ballastless track 3. The deep road cut slope grading platform 2 is located on the deep road cut slope 1.

[0102] S62. According to the design dimensions, excavate deep trenches at intervals on both sides of the roadbed to the design depth, and remove loose debris from the bottom of the trenches.

[0103] Using trenching machinery and slurry for wall protection, deep trenches are excavated at intervals along the drainage ditch design locations on both sides of the roadbed. The excavation dimensions are as determined above: trench width b, depth h, length l, and spacing a between adjacent trench sections. After the trench sections are excavated to the designed depth, loose debris at the bottom of the trench is removed.

[0104] S63. Mix polystyrene (EPS) foam particles, waste tire rubber particles and polyurethane resin (PU) in proportion and stir evenly to form a flexible composite material. Use a concrete pump to extend the pumping pipe into the bottom of the deep trench and pump the flexible composite material. At the same time, insert a vibrator. As the pumping process progresses, gradually raise the pumping pipe and the vibrator until the deep trench is evenly filled with the flexible composite material.

[0105] S64. Fill the spaced deep grooves with flexible composite material in sequence.

[0106] Flexible composite material is sequentially filled into the intermittent deep grooves until all grooves are filled.

[0107] S65. Continuously lay waterproof membrane on the top of the trench.

[0108] S66. Erect formwork on the waterproof membrane, pour drainage ditches, and cover with a cover plate.

[0109] S67. Complete the construction of the main line subgrade, water-stabilized crushed stone roadbed, track base plate, track slab, track pad piers and other structures.

[0110] like Figure 3 and Figure 4 As shown, the excavated slope 11 is the bottom of the deep road cut slope 1. In the ballastless track 3, track piers 12 are installed on the track slab 13. The bottom of the track slab 13 is provided with a rubber mortar vibration damping pad layer 17, and the bottom of the rubber mortar vibration damping pad layer 17 is the track base plate 18, which is installed on the gravel roadbed 16. The bottom of the gravel roadbed 16 is a mudstone subgrade. The deep road cut drainage ditch 4 is located at both ends of the gravel roadbed 16. The bottom of the deep road cut drainage ditch 4 is provided with a waterproof membrane 14, and the bottom of the waterproof membrane 14 is provided with a deep groove 15. The deep groove 15 is filled with a flexible barrier structure made of flexible composite material.

[0111] S7. For existing roadbeds, the following steps are included:

[0112] S71. According to the design dimensions of the trench, remove the drainage ditch covers and bottom plates at the locations where deep trenches are to be excavated on both sides of the roadbed, excavate to the design depth according to the design dimensions, and remove loose slag from the bottom of the trench.

[0113] S72. Mix polystyrene (EPS) foam particles, waste tire rubber particles and polyurethane resin (PU) in proportion and stir evenly to form a flexible composite material. Use a concrete pump to extend the pumping pipe into the bottom of the deep trench and pump the flexible composite material. At the same time, insert a vibrator. As the pumping process proceeds, gradually raise the pumping pipe and the vibrator until the deep trench is evenly filled with the flexible composite material.

[0114] S73. Fill the spaced deep grooves with flexible composite material in sequence.

[0115] S74. Continuously lay waterproof membrane on the top of the trench.

[0116] S75. Erect formwork on the waterproof membrane, re-pour the drainage ditch, and cover it with a cover plate.

[0117] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A design method for a long-term deformation barrier structure for the subgrade of a high-speed railway in soft rock deep cuttings, characterized in that, Includes the following steps: S1. Preliminary outline of the deep trench morphology of the long-term deformation barrier structure of the roadbed in soft rock deep road cut. S2. Determination of the depth h of the deep trench for the long-term deformation barrier structure of the subgrade in soft rock deep road cut; S3. Determination of the width b of the deep trench of the long-term deformation barrier structure of the subgrade in soft rock deep road cut; S4. Determination of the longitudinal length l of the deep trench along the line for the long-term deformation barrier structure of the subgrade in soft rock deep cut; S5. Determination of the net spacing 'a' of deep trenches in soft rock deep roadbed long-term deformation barrier structures; In step S2, the depth h is determined by comprehensive calculation based on the local atmospheric influence depth, annual groundwater level fluctuation, and long-term deformation characteristics of the foundation rock mass within the design service life of the deep road cut. Specifically, it includes the following sub-steps: S21. Indoor Rock Mechanics Tests: Field drilling and sampling were conducted, and conventional triaxial compression tests were performed on the sampled rock cores indoors to obtain the rock's elastic modulus E, cohesion c, and internal friction angle φ. Creep tests were also conducted using the sampled rock cores, and the creep test data were fitted using the Burgers model to obtain the rock's rheological parameters (deformation modulus k, viscosity coefficient η). （1） In the formula, σ0 is the axial loading pressure of the test, in MPa; k M η M k K η K These are the fitting parameters for the rheological model; t is time, in hours. Time-dependent expansion and deformation tests were conducted on rock cores sampled within the depth range of the atmospheric influence layer to obtain the expansion parameters N and λ. （2） In the formula, N and λ are the expansion parameters obtained from indoor tests, and t is the design service life of the subgrade; S22. Three-dimensional numerical simulation calculation: A three-dimensional geological model of the roadbed is established using a finite element program. A viscoelastic-plastic constitutive model is adopted, and the rock physical and mechanical parameters obtained from the above experiments are input. First, elastoplastic calculations are performed to obtain the elastoplastic stress field (horizontal stress σ) of the rock mass below the roadbed after excavation. x and vertical stress σ z (Distribution with depth); then, rheological calculations are performed over the design life to obtain the long-term rheological stress field (horizontal stress σ) of the rock mass below the roadbed. cx and vertical stress σ cz Distribution with depth and variation over time); S23. Determine the depth of the excavation trench: With elastic-plastic stress σ x =σ z Corresponding depth h1; The rheological stress σ within the design life cx =σ cz Corresponding rheological depth h2; The depth of the atmospheric influence layer of the rock mass within the design life is h3; The width of the roadbed in the deep cut is 0.4 times h4 = 0.4B; Determine the depth of the excavation trench: h=max(h1,h2,h3,h4) (3); The long-term deformation barrier structure for the soft rock deep roadbed includes flexible barrier structures arranged longitudinally along both sides of the roadbed. The flexible barrier structure is composed of flexible composite materials filled into deep trenches excavated in the foundation rock mass. The flexible composite material is a mixture of polystyrene (EPS) foam particles, waste tire rubber particles, and polyurethane resin (PU). Polyurethane resin (PU) is a binding material that can effectively bind the polystyrene (EPS) foam particles and waste tire rubber particles into a composite material with good compressive and tensile strength. It is also a waterproof material that can prevent groundwater infiltration and form a water-stop curtain. The polystyrene (EPS) foam particles serve as the coarse aggregate of the flexible composite material.

2. The design method for the long-term deformation barrier structure of the subgrade in soft rock deep cuttings of high-speed railways according to claim 1, characterized in that: The flexible composite filling material is mainly composed of a density of 20 kg / m³. 3 It is a mixture of polystyrene (EPS) foam particles, 20-mesh waste tire rubber particles and polyurethane resin (PU), wherein EPS foam particles account for 65-75%, waste tire rubber fragments account for 20-30%, and polyurethane resin (PU) accounts for 5-10%.

3. The design method for the long-term deformation barrier structure of the subgrade in soft rock deep cuttings of high-speed railways according to claim 1, characterized in that: In step S1, a grooving machine is used to cut grooves. The overall shape of the groove is a cuboid with rounded bottom corners.

4. The design method for the long-term deformation barrier structure of the subgrade in soft rock deep cuttings of high-speed railways according to claim 1, characterized in that: In step S3, the width is determined by the sum of the horizontal creep deformation b1 caused by stress concentration at the toe of the adjacent slope and the lateral expansion deformation b2 of the roadbed. The horizontal creep deformation b1 is taken as the horizontal deformation at the toe of the deep trench within the design life calculated in the three-dimensional numerical simulation. The lateral expansion deformation b2 of the roadbed is calculated using the following formula based on the expansion parameters obtained from the indoor time-dependent expansion test: （4） In the formula, B is the roadbed width, N and λ are the expansion parameters obtained from indoor tests, and t is the design service life of the roadbed; Considering the safety factor K, and for ease of construction, the width of the deep trench should not be less than 0.15m and not more than 0.3m, it is calculated using the following formula: when When b = 0.15m; (5) when When b = b1 + b2 (6) when When b = 0.30m (7).

5. The design method for the long-term deformation barrier structure of the subgrade in soft rock deep cuttings of high-speed railways according to claim 1, characterized in that: In step S4, the length l of a single deformable barrier structure deep groove can be 1.0-1.2 times its depth.

6. The design method for the long-term deformation barrier structure of the subgrade in soft rock deep cuttings of high-speed railways according to claim 1, characterized in that: In step S5, the net spacing length a can be taken as 0.2-0.4 times the length of the deep trench, i.e., a = (0.2~0.4)l. A larger value is taken when the rock mass strength is low and a smaller value is taken when the rock mass strength is high.

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