CZ2003790A3 - Stabilization process of particulate materials and a structure comprising a ballast bed - Google Patents

Abstract

Particulates, partially ballast in a railway track, are stabilised by adding a multi component system synthetic material selectively to the ballast in accordance with the results of analysing the results of a site survey with a mathematical model, to produce a structure of stabilised elements in the ballast, with unstabilised parts, to provide required structural reinforcement.

Description

A method for stabilizing particulate materials and a structure comprising a gravel bed

Technical field

The present invention relates to a method of stabilizing particulate materials and a structure comprising a gravel bed.

BACKGROUND OF THE INVENTION

It is known from a number of prior art designs to modify the properties of particulate engineering structures, such as a railway ballast bed, to, for example, improve stability by effectively holding the stones together. Examples are EP-A-0,502,920, EP-A-0641,407 and DE-A-394142, in which multi-component systems (MCS) such as epoxy and polyurethane resins are used to join the particulate materials together.

The technical behavior of the particulate support structures is modified when MCSs are used. In particular, the mechanical strength and stiffness characteristics are increased. In addition, the MCS also modifies dynamic characteristics, altering properties such as damping and shock wave velocity (e.g., pressure, shear and surface waves).

When applying a multi-component system to particulate materials, it is desirable to ensure that the reinforced and stabilized structure achieves an acceptable level of performance quality over its lifetime. The MCS is preferably applied in the correct spatial position and down to the correct depth to ensure that the desired improvements in technical performance are achieved. The MCS is also preferably chemically formulated to ensure that its desired properties are correct for a particular application with the use of the MCS. ·········· · · · · · · · · · · · · · · · · · · · · · · · viscosity, fatigue limits, acoustic damping, temperature range, biocidal and hygroscopic properties and curing time. Each particular MCS application is likely to be different because each location of use will be different with respect to geometry, surface and under surface design conditions and other technical characteristics. Additional additives may be required for MCS to achieve the desired behavior and predictability, such as cement or asphalt based fillers.

Incorrect application of MCS can lead to premature failure of the modified structure. In very severe cases this can lead to unplanned responses and / or catastrophic failure.

It is an object of the present invention to provide a method for treating particulate material-based structures to achieve the aforementioned requirements.

SUMMARY OF THE INVENTION

According to the invention, there is therefore provided a method of stabilizing particulate materials, comprising the steps of:

(a) examination of the surface and subsurface areas of the site of use, using sensing equipment and combining with any available existing site data;

(b) analyzing thus obtained results for determination and) where more should be applied -component system (MCS) t (ii) the amount of MCS to be used; iii ) MCS properties; and C) performing selective application of MCS to the structure so, how was determined by analysis.

Moreover, the method of the present invention preferably also comprises the steps of:

analysis of the required stress properties, and analysis of the structure of particulate materials on site.

The present invention also provides a stabilized ballast bed structure in a railway track formed by said method.

The method may comprise the further step of selecting or forming a suitable MCS coating material, for example based on polyurethane. The method of the invention allows for pre-treatment and / or modular formation of components to achieve stabilization of particulate materials and surrounding structures.

The MCS can advantageously be used to increase vertical and / or transverse structural stability (e.g. stiffness and strength) and must be carefully controlled to ensure that the stresses and forces dynamically, transiently or statically are within the specified fatigue or strength limits of the MCS reinforced structure on take consider the safety factor for the required service cycles. The use of unsuitable MCS may lead to premature and / or unpredictable failure or undesirable deterioration in the performance and behavior of the reinforced structure.

In addition, the MCS modifies the static and dynamic behavior of the particle structure and thus the full or partial response of the structure.

The change in static and dynamic behavior is associated with a variant of the MCS applied and the spatial location and structure characteristics (for example, for track applications: rails, sleepers, excavation, embankment or road applications: pavement, sidewalk, drainage, road surface, subsurface road area) , gravel bed, bed base, road surface, and so on). This change must be anticipated and considered to ensure that it is not harmful as regards the static and dynamic behavior of the applied static and transient loads.

The formation of an MCS membrane or barrier due to improper use of MCS can prevent the dispersion of excessive pore pressures on and below the surface, resulting in failure or undesirable performance of the structure. Therefore, other design aspects must be taken into account before applying the MCS, in particular whether the desired design goal is to create an impermeable interlayer to ensure the desired performance characteristics (e.g., drainage, etc.) are achieved.

When MCS is used for stabilization and consolidation, wet areas (ie areas prone to pumping sludge or mud under load) must also be carefully controlled. In addition, MCS creates a change in static and dynamic interaction behavior and can create other problems, which must be evaluated.

The use of tailored MCS results in dynamically differently behaving natural or formed structures, such as geological structures or bridge structures, which must be evaluated to ensure that the modified dynamic characteristics are appropriate. This is to prevent, for example, the generation of additional vibrations leading to load shocks or shock waves.

Particulate materials reinforced and stabilized by the method of the present invention can be used to:

• · · ·

Long-term / short-term stressed structures (eg railway track areas);

stabilize excessively sludge pumping and wet

Vertical, lateral and longitudinal stabilization (on the railway line, for example, at crossings, elevations, connections, switches, crossings and main runways, including high-speed runways), for example, to reduce maintenance required;

Stabilization of particle structures in tunnels;

Stabilization of retaining walls, slopes, taxiways and runways;

Reinforcing bridge parts, including increasing the stiffness of particulate materials before and behind bridges to prevent stress impacts;

Strengthening and stabilization to ensure that precise tolerances are maintained, for example in rail systems for standard, double-deck and high-speed trains and other types of trains;

Reduction of stresses in the upper backing layers by means of increased rigidity and strength properties of MCS;

Reducing stress in the topsheets by increasing the stiffness of the particulate material to help prevent the formation of local pockets in the topsheets;

Reducing the permanent elongation and wear of the particulate materials, separating the particulate materials (e.g., breaking), limiting the movement of the particulate material, and reducing the occurrence of impacting particles.

• · · ·

Application of MCS membranes of materials with different structures) (for example, to prevent the interface of infiltration of the gravel bed subsoil and the upper subsoil;

Assistance in preventing hydraulic erosion of surface and subsurface areas;

Enabling an increase in applied loads and transient load speeds without significantly increasing structure maintenance, and allowing reduced structure damage due to applied loads;

Preventing surface movements of particulate materials due to transient wind forces and surface waves caused by applied loads;

Limiting the generation and transmission of ambient noise;

Enabling efficient washing of reinforced structures to maintain cleanliness at reduced cost;

Improvement of static and dynamic structure behavior.

Some examples of ballast bed stabilization procedures and examples of the resulting stabilized ballast bed structures in accordance with the present invention will now be described, by way of example only, with reference to the accompanying drawings.

Overview of the drawings

Fig. 1 shows a diagram of a railway track assembly including a ballast bed and an upper backing layer, to illustrate general track features, are identified and used in the following description;

2a and 2b show a cross-sectional and longitudinal (in the direction of travel) cross-sectional view of a first embodiment of the track structure according to the present invention;

10b show

Giant. 3a and 3b to 10 and similar to FIG.

2a and 2b are cross-sectional and longitudinal cross-sectional views, respectively, of another embodiment of a track structure according to the present invention;

Fig. 11 is a view illustrating the application of gravel with MCS to a railway bed;

Fig. 12 shows a longitudinal section through an installed bridge plate; and

13 shows a flowchart for an evaluation method used in a particular case.

DETAILED DESCRIPTION OF THE INVENTION

A schematic diagram of the simplified track structure is shown in Fig. 1. Such a structure includes spaced rails 10 running parallel to the running direction of the track supported on sleepers 11 resting on the gravel layer 12. This gravel layer 12 is further supported by the substrate layer 13 resting on the substrate 14. The substrate may comprise any natural or technically modified terrain, such as embankment, excavation soil, or bridge deck. In the following drawings, the cross-sections are taken transversely across the track structure in the X-X plane in Fig. 1 and longitudinally in the Y-Y plane directions in Fig. 1.

Giant. 2a and 2b relate to the stabilization of switches, crossings and other similar types of structures that are often subjected to transverse loads due to the inertia forces of trains. Conventional stabilization methods include adding plates at the end of the sleeper and / or forming a continuous beam adjacent to the sleepers. Both of these methods rely on increasing passive resistance, but often do not function satisfactorily due to progressive plastic shifting of the underlying gravel. The technique used to overcome this problem (e.g. in this construction) is the Crib Tie-back Method (CTbM). In this technique, the polymer-impregnated gravel composite beam 15 is designed to abut the sleepers 11 to help prevent the sleepers 11 from transversely moving as before. The beam 15 is now, however, now bound to formwork or padding using composite anchors 16 of polymer impregnated gravel that extend across the track generally between and below the sleepers 11. The force required to hold the formwork anchors 16 is provided by the weight train. Thus, this technique uses the train's own weight to hold the beam 15 against permanent transverse displacement (in addition to the frictional resistance below the sleepers 11). The width of the anchors may or may not fill the entire width and / or depth of the shuttering surface depending on the amount of anchoring force required.

The polymer blend is selected based on the desired rigidity and strength properties of the composite material. More specifically, the tensile strength and shear strength of the polymer are determined as part of the design process.

Giant. Figures 3a and 3b illustrate a structure for stabilizing the vertical displacement of sleepers 11, wherein conventional problems are used to solve the weaknesses of the railway or road substructure, or switch areas subjected to high vertical forces, using conventional · «··« · ·· ·· Ladder type construction. In this construction, only the gravel under the bottom of the sleepers is stabilized as shown in Figures 3a and 3b. The ladder includes beams 17, 18 extending along the sides of the ballast, and a plurality of crossbars 19 passing through the track between beams 17, 18 and between sleepers 11. All beams 17, 18 and crossbars 19 are below sleepers 11 and utilize the full depth of the ballast layer 12; they are formed through polymer stabilization. A ladder structure (Type 1 stabilization) can only be used if the depth of the gravel layer 12 is sufficient to allow friction securing of the unstabilized gravel below the sleepers (i.e. the friction properties of the unstabilized gravel are used to secure the unstabilised screed to the adjacent formwork stabilized / paved gravel). ). In areas with a weak crown bottom, the properties of the polymer (e.g., polymer stiffness) are designed to ensure that an effective base of the stabilized pillow type gravel is constructed above the weak area. If the stiffness of the polymer is sufficiently high, a more uniform stress distribution at the transition to the substrate is achieved. For switches requiring considerable maintenance, the polymer properties are selected to ensure that large vertical forces are more effectively distributed below the switch, but still retain good cushioning properties of the composite material.

Giant. Figures 4a and 4b illustrate the Type 2 stabilization design for weak crown areas and areas requiring considerable maintenance, in which the gravel depth is not sufficient to ensure that unstabilized gravel under the sleepers is secured to the ballast-stabilized ballast (or when vertical forces are too high) large). It is therefore possible to «

Shifting and penetrating gravel under the sleepers into the crown. Lifting the ballast to stabilize the ballast directly below the sleeper is possible (but this would require a separate design), but often undesirable as this has an adverse effect on the leveling of the track. In this construction, holes 20 are drilled into the sleepers at various locations to allow the polymer to be poured / injected into the underlying gravel and to fully / partially stabilize the gravel, as shown in Figs. 4a and 4b, by creating in addition to the ladder structure of 3a and 3b, comprising parallel side beams 17, 18 and crossbars 19 below and between the sleepers 11, a plurality of anchor pillars 21 below the sleepers.

In the construction according to Figs. 5a and 5b for stabilizing wet areas, it is assumed that the gravel layer 13 of the substrate is heavily contaminated due to the infiltration of the subsoil (sludge pumping) and the gravel must be replaced before polymer treatment. The replaced gravel in the gravel layer 12 is then stabilized using a polymer to form a stabilized layer 22. The polymer is also designed to allow the formation of a sump at the interface between the gravel layer and the substrate layer by forming an integral polymer membrane 23. This membrane stops the infiltration of the subsoil, but should only be used when great confidence in the reliable function of the drainage layer is possible. The depth of the stabilized gravel (from the interface between the gravel layer and the substrate layer) may be as far as the bottom of the sleepers, if this is considered appropriate, but an unstabilized gravel layer 12 is shown.

Giant. 6a and 6b show a structure in which the polymer is used to ensure transverse lateral tolerances

4 ··· · ··· 4

94 4 4 4 4 4 4 4 4 4 4 4

444 · »· 44 444 44 44 The routes were within specified limits. For example, this design could be used to ensure that track clearances in tunnels and track platforms are within the correct limits. The depth of polymer application is generally adjusted from the top level of the sleeper below the bottom of the sleeper, as shown in Figures 6a and 6b. Generally, it is not necessary to stabilize all of the formwork areas, but this is dependent on the required load and service life levels. The stiffness of the polymer is usually set sufficiently high to ensure that the stiffness of the composite material remains high (which ensures little shifting of the composite material). As shown in this construction, side beams 24 are formed from stabilized gravel to the upper surface of the sleepers and transverse beams 25 between alternating pairs of sleepers 11.

As shown in Figures 7a and 7b, the polymer is used to form a continuous, stabilized carpet 26 on the gravel surface around the sleepers 11. The purpose of the carpet 26 is to stabilize only the gravel surface (although the depth of the carpet may extend below the sleepers if desired). high degree of stabilization).

The carpet 26 is used to stabilize gravel for wind forces generated by the train, loss of compactness due to gravel vibrations, and other damage problems such as vandalism. To solve vibration problems, the polymer stiffness is generally set low to increase the damping properties of the polymer. The vibrations can come from many sources, including the waves in the soil generated by high-speed trains (these vibrations can be large on embankment structures or railroads over weak foundations or excessive • ·

vibrations of other track structures, such as bridge slabs vibrating at their characteristic frequencies.

Giant. 8a and 8B show an embodiment for stabilizing the cyclic upper. The problems with the cyclic superstructure generally originate from problems with poor track alignment or dynamic movement of the locomotive and / or wagons. For example, an area with wet spots can create oscillations in the train suspension system that cause sinusoidal movement, causing changes in dynamic forces on the track along the length of the track. This sinusoidal movement causes a permanent displacement of the ballast at given wavelengths. The cyclic upper may also be due to problems with, for example, an uneven substrate. The design for this type of problem is based on the formation of two continuous beams 27, 28 of composite polymer material and gravel, which surround the respective area. These beams may be continuous (as shown in Fig. 8) or utilize a gravel securing mechanism including transverse beams 29 along the sleeper as described in Examples 2 & 3 below. On a straight track, transverse displacements may not be significant, and hence at certain formwork locations only stabilization of the gravel in the formwork (e.g. every third or fourth formwork) is required.

The purpose of these formwork stabilizations is to ensure that the beams 27 and 28 remain transversely connected. Since this type of stabilization is generally for long track lengths, polymer properties are selected based on the varying properties of the crown. For example, a uniform track module value can be selected as the design criterion when determining the polymer stiffness.

Finally, FIGS. 9a and 9b show a stabilized ballast arrangement for stabilizing the curves and curvature of the ballast.

2a and 2b for the track, there is no need for the railway substructure on the axles). In these • · · ·

embankment. The structure designed to increase transverse stability of the railway is sufficient (generally, the passive resistance is less than that of a track that is not situated in situations a gravel wedge 30 may be required to increase transverse stability. This gravel wedge 30 (or wedges) extends beyond the usual stabilization depth. used to increase the passive resistance of the stabilized track as shown in Figures 9a and 9b The gravel wedges may be formed of stabilized gravel as shown in Figures 9a and 9b, or may be formed of another type of material, The properties of the polymer are selected based on the criteria discussed in Example 1. The entire upper gravel portion 31 defining the slope of the curve is stabilized by the addition of the polymer. longitudinally with the track under the rails me.

Stabilized beams 31 may be used on both sides of sleepers 11 to withstand trains that are both faster and slower than the design curvature of the track. Full stabilization of the embankment can be achieved (perhaps for weak embankments) through the use of nail nailing techniques to increase strength and stiffness in combination with polymer stabilization techniques to increase the lateral (and vertical if necessary) track stability.

Giant. 10a and 10b illustrate an arrangement for reducing maintenance of a ballast bed on a main track. It is generally accepted that when constructing a new railway line, the maintenance of the line can be limited by ensuring that the surface of the subsoil (topsheet) is shaped to be parallel to the rails. This helps to avoid problems, such as gravel memory, in which the gravel surface (i.e., at the sleeper level) assumes the same shape as an uneven subsoil surface. When constructing a new track at the moment of laying gravel on the track. a polymer may be applied to ensure that the ballast layer 32 remains parallel to the rails. This gravel layer 32 is applied at a specific level and to a specific extent within the gravel depending on the desired construction and durability as shown in Figs. 10a and 10b. This type of approach helps in preventing the formation of pockets in gravel and thus reduces the likelihood of track irregularities.

When upgrading an existing track, the same technique may also be used to improve the service life of an improved track for flat / uneven subsoil. During the gravel cleaning / restoration process, the polymer can be applied in a manner similar to that described for the new track. The polymer is again used to form a lower layer of composite gravel material that is parallel to the rails. The structure will be based (for example) on stabilizing the gravel from its center point down to the uneven gravel subsoil / subsoil interface. Unstabilizing the top layer of gravel allows for conventional upsetting operations. As with the design of a new track, the polymer and load properties will be matched to the subsoil and the required load level through design criteria such as track module value. Giant. 11 illustrates a typical application of a polymer to form a composite lower surface gravel layer 32 during a gravel cleaning operation with an uneven base gravel layer and / or subsoil layer. Since this technique will be used for long track lengths, the properties of the polymers will have to change to accommodate the changing track characteristics. It is therefore likely that techniques such as ground penetrating radar survey will be required to investigate the profile of the subsoil. The split gravel hopper 33 is used to lay the first gravel layer in front of the applicator nozzle 34 and then the next untreated gravel layer 12 above the stabilized gravel layer 32.

The proposed polymer stabilization technique can be used to create transition zones to allow a more uniform change of track module during sudden track stiffness changes. For example, the polymer / gravel composite material may be used to form a transition zone from a relatively weak embankment structure to a rigid concrete bridge slab. This construction will include the spatial placement of the polymer, for example, tailor-made stabilization at a lower level leading up to the bridge, in combination with the desired changes in polymer properties. By varying the overall properties of the stabilized ballast, changes in ballast shear waves and track speeds can be achieved to modify dynamic track characteristics. The purpose of the transition zone is to help reduce problems such as train shocks that arise from sudden changes in track stiffness. The complex patterns of mutual interference created when the train approaches a solid structure due to ground waves in the track can increase the need for gravel maintenance. The proposed ballast stabilization treatment can reduce the required maintenance in these areas. An example of a concrete bridge slab stabilized with gravel before and after it is shown in Fig. 12. In this example construction, the polymer stiffness and spatial location increase as the railway line approaches the bridge slab (and vice versa away from the bridge) to allow a smoother transition from embankment to bridge. On the bridge plate, the polymer stiffness is reduced and its damping properties are increased to reduce vibration problems (with gravel wear). In these constructions, it may be desirable to incorporate rubber sheets, or other types of energy absorbing systems, under the sleeper to allow more flexible sleeper fit if deemed appropriate. The bridge slab 35 is covered with a full stabilized gravel layer 36 that is oblique at each side of the slab, while on each side of the bridge a partial stabilized gravel layer 37 is formed leading to and from the inclined ends of the layers 36.

The transition zones may be formed either by increasing the slope of the stabilized ballast, as in Fig. 12, or by employing a stepwise configuration.

An example of the application of the method of the invention, illustrated by the flowchart in Fig. 12, is the stabilization of a series of switches, through which a train with a 25 T axle load and a speed of 110 mph regularly passes. This section of the line is loaded with 35 million gross tons (MGTs) and switches are used to divert freight trains to a turning to a shunting station. The lateral (lateral) displacement of rails in switches (situated on a gravel track), measured by means of on-line connected tools on the train, is of the order of 15 to 25 mm depending on the current axle weight and speed under instant load. Switches are usually maintained at 6 to 8 monthly intervals (often the switches are re-aligned). On-site survey revealed that gravel is dolerite basalt type with a value of D _of 28 mm. The gravel depth is between 300 and 400 mm with the underlying gravel layer between • · «· · ·

120 to 150 mm, overlying the clay soil, in a slight depression. CBR data and tapered penetrometer data when investigating the subsoil indicated stiffness values in the range of 100-120 MPa. The Poisson constant for this type of material is 0.4 with shear strength coefficients c '- 4 kPa and Φ' = 29 °. On-site density data indicates a unit bulk density of about 18 kN / m ³ . The surface layering of the subsoil is known, so it was not considered necessary to use ground penetrating radar measurements.

The shear wave velocity in the subsoil is calculated to be approximately 150 m / s. At 110 mph the maximum train speed is 49 m / s. Therefore, the creation of a transeism state is not expected at the current train speeds (train speed is less than 60% of the ground shear wave speed). Critical line speeds are also outside the current train speed limits. This example therefore focuses primarily on the static analysis of the train.

The stiffness values for the gravel and undercoat are about 200 MPa and 120 MPa, respectively, with purely frictional strengths of Φ + 46 ° and Φ '+ 38 ° respectively. The gravity porosity is about 0.72 with a unit weight of 16 kN / m ³ . The rail (E-210 GPa, p = 7850 kg / m ³ ) and the rail washers (E-200 MN / m) are standard British elements with plate fasteners with screws on wooden sleepers with a length of 2.6 m, a depth of 0.14 The average distance between the sleepers is 0.38 m. No signs of sludge pumping are evident, and the formation of wet spots at this location is not considered significant. This is confirmed by the examination of well maintained drainage of the line. The gravel contamination caused by overloaded gravel is obvious. This resulted from the creation of large transverse forces as freight trains are diverted to a turn. Calculations of expected vertical and transverse forces of trains (using standard procedures, such as those recommended in the British and American Railway Designers' Handbooks (AREA)), result in a dynamic gain factor of 1.5 to 2x static axle loads vertically at 100 to 110 mph, 2x static axle loads horizontally when turning at 15 mph. These values are used in combination with the material parameters found in the on-site investigation as an input to a static mathematical model based on the finite element method.

The static mathematical model used in the DIANA finite element program, which is generally obtainable and represents the state of the art, with respect to commercially available finite element calculation programs. The 3-dimensional finite mesh used includes 2100 elements of the following types: Class III 3-node beam members and 20-node isoparametric brick members. A full integration scheme is used and the extreme conditions are smooth in suitable vertical directions and fixed at the base. The mesh is divided into several layers to simulate different depths of gravel, gravel substrate and lay. Modifying the properties of the gravel material as appropriate with their spatial distribution simulates changes in gravel densities. It is assumed that the rails, fasteners and sleepers behave elastically. It is assumed that gravel, gravel base and subsoil behave non-linearly and are modeled using an elasto-plastic Mohr-Coulomb state soil model using a non-associative plastic flow rule.

· · # # # # # # # # # # # # # # # # # # # # # # # # # # # # # · · · · · · · · ··

Expansion of the material for the gravel and the gravel substrate is assumed based on the third critical state angles for the two materials.

Locomotive arrangements for determining train load cases include: Class 87 (eg wheel diameter = 1,150 m, wheel center distance 3.28 m, chassis length 9.97 m, axle weight 202 T + 2 T unsprung), Class 86/4 and Class 253/254 HST. Examples of loading wagons include a 100 ton GLW Class B tank wagon (eg wheel diameter = 0.95 m, wheel center distance = 2.0 m, chassis length = 13 m, axle weight = 25 T). An additional multiplication factor of 1.5 is used to simulate an increase in the dynamic load factor for wheel bearing surfaces.

The mathematical model is first used to verify the values of the simultaneous lateral displacement (lateral deflection between 10 to 25 mm depending on the applied lateral force). Once the measured displacement values are simulated, the finite element model is considered to be calibrated and various structures are examined and analyzed to determine the optimal structure for the polymer-composite material to be added. The iteration method is used in combination with the newly constructed track structure to determine the properties of the desired engineered polymer. The required behavior is set to 5 mm lateral deflection of the lateral load of the train.

The actual structure used to stabilize this site is a constrained structure (several structures were examined and their performance evaluated with respect to the behavior of the target setting). In this particular case, the composite continuous beam is bonded to the formwork using a polymer composite material (bonding is formed under the bottom of the sleepers). The stiffness of the polymer used was E = 500 MPa and the ballast fill was 10% by weight of the ballast. This design shows that a substantial increase in lateral stability can be achieved compared to conventional continuous beam type stabilization. The simulated modeling showed an increase in transverse stability for this particular case to a value of approximately 6 times greater than that of conventional unstabilized gravel, and 4 times greater than for stabilization with a continuous beam only, under the stated train load conditions. The results of the mathematical model have been studied in detail in terms of stress, deformation, displacement, and the like, to ensure that these quantities are within acceptable fatigue limits for the selected composite / polymer. The mathematical model is also used to investigate areas of possible plastic deformation, creating a permanent plastic displacement, as well as to allow modification of the structure as needed and calculated safety factors.

Laboratory tests were performed to obtain optimal polymer loading for the constructed stiffness and cyclic properties of the composite. The results of these laboratory tests were used to estimate the design life of the treated site using a similar stress variation as calculated by the mathematical model. Tests include closed shear testing, three-axis compression testing (monotonic and cyclic), and cyclic extreme value testing, i.e., three-dimensional closed tests. The shear test results (dimensions 300 mm x 300 mm) indicate that non-stabilized (unstabilized) gravel for a particular polymer fill case has shear strength factors c ³ = 0 kPa and Φ '= 46 °. In addition, the polymer increases the shear strength coefficients to c ³ = 0 kPa at 10% loading (by gravel weight) into the ballast and

46 '= 46 °, indicating a significant increase in strength. These values were confirmed by compression tests in three axes. Cyclic properties of reinforced gravel were also tested. In the first of these tests, a cyclic three-axis compressive test was performed on the paved gravel at a computer simulated peak deflection state. The results showed a total plastic deformation of 0.4% at a peak cyclic stress deflection of 384 kPa (as calculated by the mathematical program) after 20,000 load cycles. The second sample was cycled at a peak load of 768 kPa (safety factor 2x for internal stress). Again, a total plastic deformation of about 0.4% was noted.

In the simulated limit test (traditional three-dimensional closed test for railway ballast), 2.66 million load cycles were applied under design load conditions on the stabilized ballast surface (through the load head) to achieve the desired MGT value in 10 years WCML load ( West Coast Main Line). The stabilized gravel showed a plastic deformation of about 1.0 mm. Typical results for cyclic unreinforced gravel tests at this load level are generally available in the literature of an overall displacement between 30 to 40 mm of unreinforced gravel is much superior to the unreinforced gravel behavior in terms of both strength and cyclic loading. There were no gravel wear.

and also include the Behavior generated values observed no features

Based on the results of mathematical modeling, the design of the structure was modified to reduce the stress concentration at the ends of the sleepers. Designing is therefore an iterative process that takes into account the results of mathematical modeling and laboratory tests in combination with expected load conditions and required design behavior criteria to achieve the optimal structure for a given set of switches and to ensure that all design criteria (displacement, deformation, stress, and so on) are within the appropriate tolerances. Therefore, the final composite structure meets all design behavior and durability criteria for a 5 mm transverse displacement limit of 10 years on the West Coast Main Line (WCML). Thus, this process provides a complete design procedure with predictability of behavior for the modified polymer-stabilized railway track. Up to this point, the post-treatment monitoring by the local maintenance provider has shown that the treated site behaves according to the design intent.

In this example, full dynamic analysis is not needed because the critical ground and track speeds are significantly greater than the current train speeds. However, if the stiffness of the subsoil is less (or any other special circumstances or conditions on the track are observed, for example significant track irregularities leading to high dynamic forces on the track), it is necessary to add an additional design step to the example described above. To enable fully dynamic construction and analysis of the railway track and subsequently polymer-modified railway track, a program for the three-dimensional dynamic element analysis method is used. This program allows the user to investigate changes in track behavior when applying polymer and represents an advanced design tool for railway designers. Examples of suitable MCS mixtures are given below. The exact proportions of the ingredients, and even the diisocyanates and polyols used in the polyurethane, can vary according to physical properties, such as viscosity, as determined by the results of the analysis process described above.

Example 1 - (Application to Railroad.)

The gravel layer comprises crushed limestone gravel with an average diameter of 4000, which is layered to a depth of 300 mm between the sleepers and the track rails.

MCS includes, for example, a polyurethane having the following composition mixed using a Graco Harocat (Trade Mark) device, and is poured onto the gravel that has been laid at a depth of 300 mm before. The base for this 3,00 mm layer of gravel is a sand carpet. The design may require an excess of polymer seeping through the gravel to provide a barrier against the upward displacement of the sand or underlay.

The polyurethane comprises the following two components, which are held separately before casting, then mixed and cast together.

Component A (Polyol)

Castor oil

Sorbitol-based polyester Polyleterdiol

Methylnaphthalene (TOTAL U (TM) Tris (2-chlorophyll) phosphate Sodium aluminosilicate (Zeolite powder (TM))

49,25% w / w% w / w% w / w% phenylmercuric fatty acid ester (Thoreat 535 (TM))

0.5% dialkyl tin-mercaptide (Fomrez UL22 (TM))

Component B (Isocyanate)

Polymeric dimethylenediphenyl diisocyanate (MDI)

0.3% by weight

100% by weight

The mixing ratio of the two components is:

Component A - 100 parts

Component B - 56 parts

The mixture, including gravel at 5% level, provides the following mechanical properties:

Bulk density: 1.55 y / cc

Compressive modulus: 100 to 800

Example 2 (Railway application)

Railway ballast with 10% filling is prepared using a mixture of polyurethane and bitumen. The isocyanate-terminated pre-polymer is added to the cationic bitumen in the following composition:

FR emulsifiable polyether based polymer 20 parts by weight

60% cationic bitumen emulsion 100 parts by weight.

The pre-polymer is assembled as follows:

PPG diol 2000 m.w.

100 parts by weight

• · to · ·· ..,. ,

EID 9086 35 parts by weight

Amgard TMCP (TM) 10 parts by weight

Vycel-U 5 parts mass.

The mixture of pre-polymer and bitumen is sprayed onto gravel in an amount to ensure 10% loading.

The mixture cured in two hours to form an elastic, rigid material whose compressive strength at 10% loading was 50 MPa at 15 ° C.

Other curing systems for the polyurethane pre-polymer include the use of alkaline agents such as sodium silicate solution, calcium hydroxide and magnesium hydroxide, and magnesium hydroxide slurry as well as emulsions of other organic polymers. These compositions can be used similarly to bond particulate material, such as gravel, to form a solid carrier composite material. The pressure, composition, amount, and location for spraying or other application to the ballast layer are determined by mathematical modeling of the effects of stress at various speeds and train loads to ensure that the polymer / ballast composite material achieves the prescribed service life under acceptable behavior. Obviously, the operation, involving a high incidence of heavy locomotives with loaded trains carrying minerals, will develop different strains than relatively light but fast Hubble units or low-frequency slower and lighter passenger units.

The polymer blend allows the gravel to be dehumidified and subsequently to form a rigid composite material in place of the rail bed that can withstand long-term loads and vibration on the track.

Claims (11)

PATENT CLAIMS A method for stabilizing particulate materials, comprising the steps of: (a) examination of site conditions, including surface and subsurface areas of the site, using sensing equipment; (b) analyzing the results obtained to determine: i) where the multi-component system (MCS) mixture is to be applied; (ii) the quantities of MCS to be used; (iii) the characteristics of the required MCS; and c) performing selective application of MCS to the particulate materials in place as determined in step b). The method of claim 1, further comprising the steps of: analysis of required stress characteristics; and in-situ particle structure analysis. The method of claim 2, comprising the further step of selecting or forming a suitable MCS coating material. Method according to any one of the preceding claims, characterized in that the MCS is selectively applied to the ballast in the railway track system to create a stabilized ballast structure, wherein the ballast parts are stabilized and the other parts are left untreated with the MCS. Method according to claim 4, characterized in that the MCS comprises a polyurethane-based resin system which is used for joining and thus for stabilizing the gravel stones forming the railway ballast bed. A structure comprising a ballast bed in a railway track, characterized in that the ballast is selectively treated with MCS to stabilize parts of the ballast and treatment, wherein the ballast bed elements are stabilized. leaving other parts without a part of the ballast formed by reinforcing by passing through 6 to 7, pour organic on moisture or curing as a donor; and A structure according to claim 7, characterized by stabilized ballast sections comprising elements longitudinally with a track outside the sleepers, and other elements transverse to the track below and between the sleepers. Structure according to any one of the claims, characterized in that the MCS comprises a one-component polymer or polymer precursor, which can be gravel and cured by reaction with atmospheric oxygen, evaporation, subsequent application of the reagent, radiation treatment, or melting application to gravel. Structure according to any one of claims 8 to 7, characterized in that the MCS comprises two or more components which are premixed before being poured onto the gravel. Structure according to any one of claims 6 to 9, characterized in that the polymer is mixed with gravel before being deposited on the ballast bed and curing the polymer. Structure according to any one of claims 6 to 10, characterized in that it is formed by a method according to any one of claims 1 to 5.