A Method for Determination of Interfacial Frictional Parameters of Geocomposite with Crusher Dust Under Oblique Pull

Abstract

ABSTRACT: Title: A Method for Determination of Interfacial Frictional Parameters of Geocomposite with Crusher Dust Under Oblique Pull The present disclosure proposes a method for determining interfacial frictional parameters of geocomposite materials used in reinforced embankments, utilizing crusher dust as fill material. The proposed method utilizes a large-scale pull-out test box to provide more realistic testing conditions that closely mimic on-site environments, enhancing the reliability of data for engineering applications. The proposed method evaluates key parameters such as interfacial shear parameters (cohesion Ci, adhesion Ca) and friction coefficients (μ), providing a holistic assessment of the performance of geocomposite reinforcement materials under different placement (horizontal and oblique) conditions. The proposed method is intended for geocomposite reinforcement and crusher dust used as fill material in geotechnical engineering, thereby allowing for tailored data, leading to more efficient design and construction practices.

Specification

Description:DESCRIPTION:
Field of the invention:
[0001] The present disclosure generally relates to the technical field of Geotechnical Engineering, and in specific, relates to a method for evaluating interfacial frictional parameters of geocomposite reinforcements used in reinforced embankments under oblique placement with crusher dust as fill material.
Background of the invention:
[0002] Geosynthetics are used in Civil Engineering construction works to enhance soil stability by distributing stresses and providing necessary strength, yet a significant challenge remains in the form of measuring geosynthetic frictional strength in oblique placement of reinforcement. Existing small scale experimental setups are insufficient to capture the complex in-situ stress conditions faced by geosynthetics particularly under oblique placement.

[0003] Geocomposites are engineered materials composed of a geotextile fabric combined with a geomembrane or other synthetic material. They are widely used in geotechnical engineering applications to improve soil stability, drainage, and filtration. The interfacial friction between the geocomposite and the surrounding soil is a crucial factor in determining its effectiveness.

[0004] Pull-out tests are a common laboratory method used to evaluate the interfacial strength between a geocomposite and the surrounding soil. In a pull-out test, a geocomposite strip is embedded in the soil and subjected to a vertical normal loading and a horizontal pulling force. The force required to pull the geocomposite out of the soil is measured and used to calculate the interfacial shear strength. Pull-out tests provide a direct and quantitative measure of the interfacial shear strength, which is a crucial parameter for assessing the performance of geocomposites in various geotechnical applications. The pull-out test can be designed to simulate the loading conditions that a geocomposite might experience in the field, such as tensile forces or uplift pressures. Placement of reinforcement in oblique condition significantly influence the interfacial frictional parameters and other stress considerations.

[0005] However, based on the knowledge of geotechnical engineering and soil mechanics, it can be inferred that the following technologies are likely relevant to the field and may have been considered in the development of the invention. The geotechnical testing equipment includes devices such as shear boxes, load cells, LVDT which are used to measure the strength and deformation properties of geocomposite material used. The fill material used is tested to determine basic properties, such as particle size distribution, consistency limits, and unit weight.

[0006] Therefore, there is a need for a method for evaluating interfacial frictional parameters of geocomposite materials under oblique pull condition used in reinforced embankments and subgrades, utilizing crusher dust as fill material. There is also a need for a method that conforms to a more accurate evaluation of interfacial frictional parameters between geocomposite and crusher dust by incorporating different oblique pullout angles of inclination, thereby offering insights into performance. Furthermore, there is also a need for a method that accommodates a range of inclinations (5 to 15 degrees), thereby allowing a user to simulate various practical scenarios for geosynthetic installations in reinforced embankment.
Objectives of the invention:
[0007] The primary objective of the present invention is to provide a method for evaluating interfacial frictional parameters of geocomposite reinforcements used in reinforced embankments under oblique placement with crusher dust as fill material.

[0008] Another objective of the present invention is to provide a method that evaluates interfacial frictional parameters between the geocomposite reinforcement and crusher dust by incorporating different oblique placement with varying inclinations thereby offering insights into performance.

[0009] Another objective of the present invention is to provide a method that accommodates a range of inclinations (5 to 15 degrees), thereby allowing a user to simulate various practical scenarios for geosynthetic installations in reinforced embankment.

[0010] Another objective of the present invention is to provide a method that utilizes a large-scale pullout test box to provide more realistic testing conditions that closely mimic field placement of reinforcement, thereby enhancing the reliability of data for engineering applications.

[0011] Another objective of the present invention is to provide a method that evaluates key parameters such as interfacial shear parameters (adhesion Ca) and interfacial friction coefficients (μ), providing a holistic assessment of the performance of geocomposite reinforcement material under different stress conditions.

[0012] Another objective of the present invention is to provide a method that is intended for geocomposite reinforcement materials and marginal material crusher dust as fill material in geotechnical engineering, thereby allowing for tailored data, leading to more efficient design and construction practices.

[0013] Another objective of the present invention is to provide a method that demonstrates that the friction coefficients decrease by 10% for every 5 degrees increase in upward inclination to optimize reinforcement placement for maximum efficiency.

[0014] Yet another objective of the present invention is to provide a method that observes that cohesion values decrease with increasing normal stress due to the dilatancy effect in crusher dust.

[0015] Further objective of the present invention is to provide a method that incorporates both horizontal and oblique pulls and summarize the behavior of reinforced embankments under different stress conditions, thereby leading to safer and more cost-effective designs for construction projects.
Summary of the invention:
[0016] The present disclosure proposes a method for determining interfacial frictional parameters of geocomposite under oblique pull with crusher dust. The following presents a simplified summary in order to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview. It is not intended to identify key/critical elements or to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0017] In order to overcome the above deficiencies of the prior art, the present disclosure is to solve the technical problem to provide a method for evaluating interfacial frictional parameters of geocomposite reinforcement used in reinforced embankments under oblique placement with crusher dust as fill material.

[0018] According to one aspect, the invention provides a method for determining interfacial frictional parameters of geocomposite reinforcement. At one step, the user fills crusher dust material in a pull-out box up to half portion, and compact the crusher dust material to a desired density to eliminate space between particles of the crusher dust material, thereby forming a first layer.

[0019] At another step, the user places a geocomposite reinforcement layer over the first layer of the crusher dust material within the pull-out box of a large-scale pull-out test apparatus. At another step, the user fills the crusher dust material on the geocomposite reinforcement and compacts the crusher dust material to the desired density to form a second layer.

[0020] At another step, the user applies a normal stress on the second layer within the pull-out box. Further, at another step, the user pulls the geocomposite reinforcement placed in between the first layer and the second layer at multiple oblique placements of 0, 5, 10, and 15 degrees with respect to horizontal in both upward and downward directions, thereby determining interfacial frictional angle (δ), friction coefficient (µ), and interaction coefficient (Ci) of the geocomposite reinforcement.

[0021] In one embodiment, the interfacial friction coefficient (µ) of the crusher dust material with the geocomposite reinforcement decreases from approximately 0.77 to 0.54 under upward inclination and increases from approximately 0.77 to 1.02 under downward inclination, when tested under optimum moisture content-maximum dry density (OMC-MDD) conditions. In another embodiment, the interfacial frictional coefficient (µ) of the crusher dust material decreases by approximately 10 percent for every 5 degrees increase in the upward oblique inclination.

[0022] In one embodiment, the interfacial frictional angle (δ) decreases to approximately 28 degrees, representing a reduction of about 26 percent under upward oblique placement conditions, and increases to approximately 46 degrees, representing an increase of about 21 percent under downward oblique placement conditions, as compared to a frictional angle of 38 degrees under horizontal placement conditions.

[0023] In one embodiment, the interaction coefficient (Ci) value is decreased with increase in normal stress due to dilatancy effect in the crusher dust material. In one embodiment, the oblique placement of the geocomposite reinforcement exhibits a more pronounced effect in the downward gradient compared to the upward gradient, relative to the horizontal placement.

[0024] In one embodiment, the crusher dust material includes a fines content of approximately 5%, which is less than 15%, and an internal friction angle of approximately 35 degrees, which is greater than 25 degrees, thereby meeting the criteria for use as a frictional fill material in reinforced soil structures.

[0025] Further, objects and advantages of the present invention will be apparent from a study of the following portion of the specification, the claims, and the attached drawings.
Detailed description of drawings:
[0026] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, explain the principles of the invention.

[0027] FIG. 1 illustrates a flowchart of a method for evaluating interfacial frictional parameters of geocomposite reinforcement, in accordance to an exemplary embodiment of the invention.

[0028] FIG. 2 illustrates a graphical representation of a pull-out displacement response of the geocomposite reinforcement embedded in the crusher dust material under different applied normal stresses in accordance to an exemplary embodiment of the invention.

[0029] FIG. 3 illustrates a graphical representation of variation of interaction coefficient at various levels of normal stresses performed under different oblique conditions of the geocomposite reinforcement within the crusher dust material, in accordance to an exemplary embodiment of the invention.

[0030] FIG. 4 illustrates a graphical representation of failure envelope of crusher dust material at 5 degrees at an upward inclination, in accordance to an exemplary embodiment of the invention.
Detailed invention disclosure:
[0031] Various embodiments of the present invention will be described in reference to the accompanying drawings. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps.

[0032] The present disclosure has been made with a view towards solving the problem with the prior art described above, and it is an object of the present invention to provide a method for evaluating interfacial frictional parameters of geocomposite reinforcement used in reinforced embankments under oblique placement with crusher dust as fill material.

[0033] According to one exemplary embodiment of the invention, FIG. 1 refers to a flowchart 100 of a method for evaluating interfacial frictional parameters of geocomposite reinforcement. At step 102, the user fills crusher dust material in a pull-out box up to s half portion, and compacts the crusher dust material to a desired density to eliminate space between particles of the crusher dust material, thereby forming a first layer.

[0034] At step 104, the user places a geocomposite over the first layer of the crusher dust material within the pull-out box of a large-scale pull-out test apparatus. At step 106, the user fills the crusher dust material on the geocomposite reinforcement and compacts the crusher dust material to the desired density to form a second layer.

[0035] At step 108, the user applies a normal stress on the second layer within the pull-out box. Further, at step 110, the user pulls the geocomposite reinforcement placed in between the first layer and second layer at multiple oblique placements of 0, 5, 10, and 15 degrees with respect to horizontal in both upward and downward directions, thereby determining interfacial frictional angle (δ), friction coefficient (µ), and interaction coefficient (Ci) of the geocomposite.

[0036] In one embodiment, the interfacial friction coefficient (µ) of the crusher dust material with the geocomposite decreases from approximately 0.77 to 0.54 under upward inclination and increases from approximately 0.77 to 1.02 under downward inclination, when tested under optimum moisture content-maximum dry density (OMC-MDD) conditions. In another embodiment, the interfacial frictional coefficient (µ) of the crusher dust material decreases by approximately 10 percent for every 5 degrees increase in the upward oblique inclination.

[0037] In one embodiment herein, the interfacial frictional angle (δ) decreases to approximately 28 degrees, representing a reduction of about 26 percent under upward oblique placement conditions, and increases to approximately 46 degrees, representing an increase of about 21 percent under downward oblique placement conditions, as compared to a frictional angle of 38 degrees under horizontal placement conditions.

[0038] In one embodiment herein, the interaction coefficient (Ci) value is decreased with increase in normal stress due to dilatancy effect in the crusher dust material. In one embodiment, the oblique placement of the geocomposite member exhibits a more pronounced effect in the downward gradient compared to the upward gradient, relative to the horizontal placement.

[0039] In one embodiment herein, the crusher dust material includes a fines content of approximately 5%, which is less than 15%, and an internal friction angle of approximately 35 degrees, which is greater than 25 degrees, thereby meeting the criteria for use as a frictional fill material in reinforced soil structures.

[0040] In one embodiment herein, the friction coefficient is referred to as the ratio of interface shear stress at failure to the normal stress. The actual behaviour of the crusher dust material and the geocomposite reinforcement, when it is subjected to a pull-out force due to the earth pressure, can ideally be simulated in the laboratory through pull-out tests. The pull-out test assist in assessing the frictional interaction between the crusher dust material and the geocomposite reinforcement, thereby determining friction coefficient of the geocomposite reinforcement with the crusher dust material.

[0041] Table. 1
S. no Engineering property Value
1. Specific gravity 2.6
2. Grain size analysis
(a) Gravel size (%)
(b) Sand size (%)
(c) Fines (%)
1
94
5
3. (a) Coefficient of uniformity
(b) Coefficient of curvature 5.7
1.1
4. Plasticity Characteristics
(a) Liquid limit (%)
(b) Plastic limit (%) Non-plastic
Non-plastic
5. Equivalent IS classification symbol SP (Poorly graded sand)
6. Compaction characteristics
(from IS heavy compaction test)
(a) Maximum dry density (g/cc)
(b) Optimum moisture content (%)

2.13
8.5
7. Shear strength parameters
(a) OMC & MDD conditions
1. Cohesion (KN/m2)
2. Angle of internal friction (φ)
(b) Saturation condition
1. Cohesion (KN/m2)
2. Angle of internal friction (φ)

0
35

0
33

[0042] In one embodiment herein, the table. 1 provides properties of crusher dust, including its compaction, shear strength, and grain size distribution, which are essential for its performance in reinforced soil structures. The specific gravity of the crusher dust material is 2.63. The grain size analysis of the crusher dust material showed the presence of 1 percent of gravel, 94 percent of sand, and 5 percent of fines, making it predominantly sandy. The Coefficient of Uniformity (Cu = 5.7) and Coefficient of Curvature (Cc = 1.1) values indicate a well-graded soil with adequate uniformity and particle distribution.

[0043] The crusher dust material is non-plastic, confirming that it has no significant clay or silt content that would affect its plasticity. The maximum dry density is 2.13 g/cc with an optimum moisture content of 8.5%, showing good compaction and density under controlled moisture conditions. In saturated conditions, the angle of internal friction (φ) slightly reduces to 33 degrees, with no cohesion.

[0044] The geocomposite reinforcement is a combination of two or more different types of geosynthetic material include geotextile-geonet, geotextile-geogrid, geonet-geomembrane and any other materials. The geocomposite reinforcement serves the function of reinforcement as well as drainage. The selected geocomposite reinforcement explored in the combination of geogrid and geotextile. The physical and mechanical properties of geocomposite reinforcement material are represented in table. 2.

[0045] Table. 2:
S. No Property Value
1 Mass per unit area (g/m2) 500
2 Nominal thickness (mm) 2.6
3 Compressibility (mm/kPa) 0.04
4 Tensile strength (KN/m) 100

[0046] The pull-out test is conducted in accordance with ASTM D 6706, the standard for large pull-out apparatus as specified by the American Society for Testing and Materials (ASTM). The pull-out box used has internal dimensions of 900 mm in length, 600 mm in width, and 600 mm in height, with a 12 mm thick horizontal slot designed to accommodate the geocomposite reinforcement within the crusher dust material. A geocomposite reinforcement measuring 45 cm by 15 cm is embedded between two layers of crusher dust.

[0047] The horizontal pullout force is then applied to the geocomposite reinforcement, which is tested under varying oblique angles of 0, 5, 10, and 15 degrees, in both upward and downward directions with respect to the horizontal. The force required to pull the geocomposite reinforcement out is measured, and the resistance and anchorage strength are calculated by dividing the pull-out force by the width of the geocomposite reinforcement. The test is repeated under normal stresses of 1.850² kN/m², 3.70 kN/m2 and 5.55 kN/m².

[0048] According to another exemplary embodiment of the invention, FIG. 2 refers to a graphical representation 200 of pull-out displacement response of the geocomposite reinforcement embedded in the crusher dust material under a vertical stress of 1.85 kN/m2. In one embodiment herein, the pull-out force gradually increases with displacement, reaching approximately 1.3 kN at around 100 mm displacement.

[0049] In one embodiment herein, the upward inclination of the geocomposite reinforcement at the 5 degrees that represent a moderate pull-out force response, reaching about 0.7 kN at 80 mm displacement, lower than the 0° inclination. The values at upward inclination of the geocomposite reinforcement at 10 degrees, the force decreases slightly more than the 5° inclination, reaching about 0.5 kN at 80 mm displacement. The upward inclination of the geocomposite reinforcement at 15 degrees, the force exhibits the lowest pull-out force among the upward inclinations, at approximately 0.4 kN.

[0050] The downward inclination of the geocomposite reinforcement under the 5 degrees, exhibits a relatively strong response, with pull-out force reaching about 0.9kN at around 90mm displacement. The downward inclination of the geocomposite reinforcement at 10 degrees represents a similar trend to 5° down with a slightly higher peak pull-out force of around 1.1kN. The downward inclination of the geocomposite reinforcement at 15 degrees exhibits highest response at around 1.2kN. The graph effectively demonstrates the sensitivity of pull-out forces to changes in the inclination of the geocomposite reinforcement, with downward inclinations to provide more resistance compared to upward inclination.

[0051] According to another exemplary embodiment of the invention, FIG. 3 refers to a graphical representation 300 of variation of interaction coefficient at various levels of normal stresses performed under different oblique conditions of the geocomposite reinforcement within the crusher dust material. In upward inclination of the geocomposite reinforcement at 5 degrees, the interaction coefficient started at around 1.05 and gradually decreased to about 0.9, thereby showing a lower interaction coefficient than horizontal placement. The upward inclination of the geocomposite reinforcement at 10 degrees, the interaction coefficient is further reduced from 0.85 to about 0.8. The upward inclination of the geocomposite reinforcement at 15 degrees, the interaction coefficient starts at about 0.8 and decreases to approximately 0.75 indicating that upward inclinations significantly reduce the interaction between the geocomposite reinforcement and crusher dust material.

[0052] The downward inclination of the geocomposite reinforcement at 5 degrees, the interaction coefficient started at around 1.25 and decreases to approximately 1.15. The downward inclination of the geocomposite reinforcement at 10 degrees, the interaction coefficient starts at around 1.35 and decreases to approximately 1.25. The downward inclination of the geocomposite reinforcement at 15 degrees, the interaction coefficient starts at about 1.55 and decreases to approximately 1.4. This is among the highest interaction coefficients for oblique placement.

[0053] According to another exemplary embodiment of the invention, FIG. 4 refers to a graphical representation 400 of failure envelope of the crusher dust material at 5 degrees at an upward inclination. In one embodiment herein, the x-axis represents the normal stress (kN/m²), ranging from 0 to 12 kN/m². The y-axis represents the pullout resistance (kN/m²), which measures the resistance encountered during the pullout of geocomposite reinforcement embedded in crusher dust material. The line represents the failure envelope, which is essentially a straight line that defines the critical failure condition under different normal stresses. The data points represent the actual pullout resistance measurements at various levels of normal stress.

[0054] The failure envelope is a critical tool in understanding the limit of pullout resistance for the crusher dust material at the specified inclination. The linear relationship implies a predictable increase in pullout resistance with normal stress under the 5° upward inclination. The observed pullout resistance values at different normal stresses suggest that higher normal stresses lead to greater material interaction, improving the geocomposite reinforcement overall pullout resistance.

[0055] Numerous advantages of the present disclosure may be apparent from the discussion above. In accordance with the present disclosure, the method for evaluating interfacial frictional parameters of geocomposite reinforcement is disclosed. The proposed method evaluates interfacial frictional parameters between geocomposite reinforcement and crusher dust by incorporating different angles of inclination, thereby offering insights into performance. The proposed method accommodates a range of inclinations (5 to 15 degrees), thereby allowing a user to simulate various practical scenarios for geosynthetic installations in reinforced embankment.

[0056] The proposed method utilizes a large-scale pullout test box to provide more realistic testing conditions that closely mimic on-site environments, enhancing the reliability of data for engineering applications. The proposed method evaluates key parameters such as interfacial shear parameters (cohesion Ci, adhesion Ca) and friction coefficients (μ), providing a holistic assessment of the performance of geocomposite reinforcement under different stress conditions. The proposed method is intended for geocomposite reinforcement material as reinforcement, crusher dust as fill material in geotechnical engineering, thereby allowing for tailored data, leading to more efficient design and construction practices for reinforced embankments.

[0057] The proposed method demonstrates the friction coefficients decrease by 10% for every 5 degrees increase in upward inclination to optimize reinforcement placement for maximum efficiency. The proposed method observes that cohesion values decrease with increasing normal stress due to the dilatancy effect in crusher dust. The proposed method incorporates both horizontal and oblique pulls and enables more complete reinforced embankments to behave under different stress conditions, thereby leading to safer and more cost-effective designs for construction projects.

[0058] It will readily be apparent that numerous modifications and alterations can be made to the processes described in the foregoing examples without departing from the principles underlying the invention, and all such modifications and alterations are intended to be embraced by this application.
, Claims:CLAIMS:
I/We Claim:
1. A method for evaluating interfacial frictional parameters of a geocomposite reinforcement, comprising:
filling a crusher dust material in a pull-out box up to half portion, and compacting the crusher dust material to a desired density to eliminate space between particles of the crusher dust material, thereby forming a first layer;
placing the geocomposite reinforcement over the first layer of the crusher dust material within the pull-out box of a large-scale pull-out test apparatus;
filling the crusher dust material on the geocomposite reinforcement and compacting the crusher dust material to the desired density to form a second layer;
applying a normal stress on the second layer within the pull-out box; and
pulling the geocomposite reinforcement placed in between the first layer and the second layer at multiple oblique angles of 0, 5, 10, and 15 degrees with respect horizontal in both upward and downward directions, thereby determining interfacial frictional angle (δ), friction coefficient (µ), and interaction coefficient (Ci) of the geocomposite reinforcement.
2. The method as claimed in claim 1, wherein the interfacial friction coefficient (µ) of the crusher dust material with the geocomposite reinforcement decreases from approximately 0.77 to 0.54 under upward inclination and increases from approximately 0.77 to 1.02 under downward inclination, when tested under optimum moisture content and maximum dry density (OMC-MDD) conditions.
3. The method as claimed in claim 1, wherein the interfacial frictional coefficient (µ) of the crusher dust material decreases by approximately 10 percent for every 5 degrees increase in the upward oblique inclination.
4. The method as claimed in claim 1, wherein the interaction coefficient (Ci) value is decreased with increase in normal stress due to dilatancy effect in the crusher dust material.
5. The method as claimed in claim 1, wherein the oblique placement of the geocomposite reinforcement exhibits a more pronounced effect in the downward gradient compared to the upward gradient, relative to the horizontal placement.
6. The method as claimed in claim 1, wherein the interfacial frictional angle (δ) decreases to approximately 28 degrees, representing a reduction of about 26 percent under upward oblique placement conditions, and increases to approximately 46 degrees, representing an increase of about 21 percent under downward oblique placement conditions, as compared to a frictional angle of 38 degrees under horizontal placement conditions.
7. The method as claimed in claim 1, wherein the crusher dust material includes a fines content of approximately 5%, which is less than 15%, and an internal friction angle of approximately 35 degrees, which is greater than 25 degrees, thereby meeting the criteria for use as a frictional fill material in reinforced soil structures.

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