Description:DESCRIPTION:
Field of the invention:
[0001] The present disclosure generally relates to the technical field of geo-technical engineering and pavement design, in specific, relates to a method for determining California bearing ratio (CBR) of pavement subgrade using dynamic cone penetration index (DCPI) for silty sand and clayey silty sand.
Background of the invention:
[0002] Flexible pavements have been the predominant type of road used in Saudi Arabia and other parts of the world, with most paved surfaces falling under this category. They can be classified as either conventional or full-depth pavements. Conventional flexible pavements are layered systems comprising an asphalt mixture (wearing course) over one or more granular layers (base and sub-base), all constructed over sub-grade soil. The granular base and sub-base layers are crucial components that reduce traffic-induced stresses and minimize rutting in the base, sub-base, and sub-grade.

[0003] All pavement systems are built on earth, with nearly all components made from earth materials. A typical flexible pavement consists of a bituminous composite wearing course built over a base course and sub-base, which rest on a compacted subgrade. The base may be stabilized with asphalt, cement, lime, or other stabilizers, or left untreated, using granular material with specific physical properties.

[0004] In general, concrete refers to any material made of a mixture of aggregates, such as sand, gravel, or crushed stone, bound together by cement. Asphalt concrete is composed of asphalt cement and aggregate. Base courses typically consist of aggregates like gravel and crushed rock, which may be compacted or stabilized with lime, Portland cement, or asphalt. Sub-bases usually use local aggregate materials and can be either compacted aggregate or stabilized materials. The purpose of the subgrade is to provide a platform for pavement construction and to support the pavement without excessive deflection that would affect its performance.
[0005] Traditionally, the California Bearing Ratio (CBR) test is a widely recognized method for evaluating the strength of subgrade soils and base materials used in road construction. Developed by the California Division of Highways in the 19th century, the CBR test measures the resistance of a soil sample to penetration by a standardized piston under controlled moisture and density conditions. The test is performed by compacting soil in a mold, saturating it (in soaked conditions), and then applying a load to measure the pressure required to achieve a specified penetration depth.

[0006] Despite its widespread use and acceptance, the CBR test has several limitations. It is labor-intensive, time-consuming, and requires specialized laboratory equipment and conditions, making it less suitable for rapid on-site evaluations. Furthermore, the results can vary significantly depending on the soil type, moisture content, and compaction level, necessitating careful sample preparation and testing procedures.

[0007] To address these challenges, alternative methods such as the Dynamic Cone Penetration Test (DCPT) have been developed. DCPT offers a quicker and more cost-effective means of assessing soil strength directly in the field. However, DCPT measurements need to be correlated with CBR values to provide meaningful data for pavement design and construction.

[0008] In existing technology, a method for predicting the California bearing ratio of subgrade material, includes collecting sample from various regions within the subgrade, which are then tested to determine the moisture content and density. Each sample is prepared at optimal moisture content and various densities, succeeded by testing to ascertain the CBR for each density, thereby generating a dataset of variables. Selected variables from this dataset are subjected to a multiple linear regression model, establishing a relationship between the determined CBR value and these variables. However, the method might not provide accurate results.

[0009] Therefore, there is a need for a method for determining California bearing ratio (CBR) of pavement subgrade using dynamic cone penetration index (DCPI) for silty sand and clayey silty sand. There is also a need for a method that correlates DCPI and CBR values through comprehensive field and laboratory testing. There is also a need for a method that provides a more efficient, accurate, and economical approach to evaluating soil strength for civil engineering applications. Further, there is also a need for a method that incorporates a field density test using the core cutter for collection of undisturbed soil samples along with DCPI to enhance the comprehensiveness and reliability of the soil-specific correlations developed.
Objectives of the invention:
[0010] The primary objective of the present invention is to provide a method for determining California bearing ratio (CBR) of pavement subgrade using dynamic cone penetration index (DCPI) for silty sand and clayey silty sand.

[0011] Another objective of the present invention is to provide a method that develops correlations between CBR and DCPI based on data collecting during both pre-monsoon and monsoon periods and, under laboratory conditions of soaked and unsoaked states, enhances the reliability of the correlations across different environmental conditions.

[0012] The other objective of the present invention is to provide a method that conducts DCPI tests up to 1000 mm depth with a typical highway penetration depth of 900 mm using an extension rod, ensuring that the method is applicable for depths relevant to highway construction and maintenance.

[0013] The other objective of the present invention is to provide a method that establishes soil-specific correlations between CBR values obtained in the laboratory and DCPT measurements from field tests for silty sand (SM) and clayey silty sand (SC-SM) to improve the accuracy and applicability of soil strength evaluations.

[0014] The other objective of the present invention is to provide a method that performs DCP tests in the field during varying seasons, and conducting CBR tests in the laboratory under different moisture conditions, various soil properties such as specific gravity, grain size distribution, atterberg limits, field moisture content, and density are determined for different depths at selected locations.

[0015] The other objective of the present invention is to provide a method that utilizes data collected from different depths in the field to ensure that the correlations developed are robust and applicable across varying soil conditions and depths.

[0016] Yet another objective of the present invention is to provide a method that incorporates a field density test using the core cutter for collection of undisturbed soil samples along with DCPI to enhance the comprehensiveness and reliability of the soil-specific correlations developed.

[0017] Further objective of the present invention is to provide a method within controlled standardized conditions for compacting soil samples in the CBR mould to match field moisture content (FMC) and field dry density (FDD) ensures the consistency and accuracy of soil-specific correlations under different environmental conditions.
Summary of the invention:
[0018] The present disclosure proposes method for determining california bearing ratio (CBR) of silty sand and clayey silty sand subgrades. 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.

[0019] 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 determining California bearing ratio (CBR) of pavement subgrade using dynamic cone penetration index (DCPI) for silty sand and clayey silty sand.

[0020] According to one aspect, the invention provides a method for determining California bearing ratio of silty sand and clayey silty sand. At one step, the dynamic cone penetration tests (DCPT) are performed at selected locations of silty sand and clayey silty sand. At another step, the penetration depth measures for each cumulative weight drop of the hammer while performing DCPT is recorded and DCPI (Dynamic cone penetration index) is determined.

[0021] At another step, the representative soil samples are collected from the selected locations corresponding to the desired depth. At another step, the collected soil samples are allows to perform laboratory test to determine the specific gravity, grain size distribution, atterberg limits, field moisture content, and field density. In one embodiment, the atterberg limits of soil are determined i.e., liquid limit and plastic limit.

[0022] At another step, the California bearing ratio (CBR) test conducted on the collected soil sample in the laboratory under two conditions. Further, at another step, the correlation is established between the DCPI obtained from the DCPT measurements and the CBR value determined from the laboratory CBR test to enhance the reliability of the estimated CBR valves for pavement design purposes.

[0023] In one embodiment, the soil samples are collected from different depths in the field to enhance the accuracy and applicability of the developed correlations. In one embodiment, the correlation is established based on the DCPT values obtained from depths up to 1000 mm in which the test is conducted using an extension rod.

[0024] In one embodiment, the DCPT is conducted during pre-monsoon and monsoon seasons to stimulate for seasonal variations in soil conditions. In one embodiment, the CBR tests are performed under two conditions, which include unsoaked and soaked conditions to stimulate different moisture states of the soil. In one embodiment, the laboratory CBR test is conducted on the soil sample compacted to corresponding to the field moisture content and field dry density (FMC-FDD).

[0025] In one embodiment, the correlations between CBR values and DCPT measurements provide a quick, economic, and accurate means for evaluating the subgrade soil strength of silty sand (SM) and clayey silty sand (SC-SM). In one embodiment, the correlation incorporates a field density test using a core cutter method performed at the desired location and corresponding depth of the desired DCPT.

[0026] 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:
[0027] 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.

[0028] FIG. 1 illustrates a flowchart of a method for determining a california bearing ratio (CBR) of silty sand and clayey silty sand, in accordance to an exemplary embodiment of the invention.

[0029] FIG. 2 illustrates a schematic view of a dynamic cone penetrometer, in accordance to an exemplary embodiment of the invention.

[0030] FIG. 3 illustrates a flowchart of the determination of the subgrade strength of silty sand and clayey silty sand, in accordance to an exemplary embodiment of the invention.

[0031] FIG. 4A illustrates a graphical representation of dynamic cone penetration index (DCPI) against CBR during a pre-monsoon season, in accordance to an exemplary embodiment of the invention.

[0032] FIG. 4B illustrates a graphical representation of the DCPI against CBR during monsoon season, in accordance to an exemplary embodiment of the invention.

[0033] FIG. 4C illustrates a graphical representation of the DCPI against CBR during both pre-monsoon and monsoon seasons, in accordance to an exemplary embodiment of the invention.
Detailed invention disclosure:
[0034] 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.

[0035] 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 determining California bearing ratio (CBR) of pavement subgrade using dynamic cone penetration index (DCPI) for silty sand and clayey silty sand.

[0036] According to one exemplary embodiment of the invention, FIG. 1 refers to a flowchart 100 of a method for determining California bearing ratio of silty sand and clayey silty sand. At step 102, the dynamic cone penetration test (DCPT) conducted at the selected locations for silty sand and clayey silty sand. At step 104, the penetration depth measures for each cumulative weight drop of the hammer while conducting the DCPT.

[0037] At step 106, the representative soil samples are collected from the selected locations corresponding to the desired depth. At step 108, the collected soil samples are tested in the laboratory to determine the specific gravity, grain size distribution, Atterberg limits, field moisture content, and field density. In one embodiment, the Atterberg limits are determined i.e., liquid limit and plastic limit.

[0038] At step 110, the California bearing ratio (CBR) test is performed on the collected soil sample in the laboratory under two conditions. Further, at step 112, the establishes a correlation between the DCPI obtained from the DCPT measurements and the CBR value determined from the laboratory CBR test to enhance the reliability of the estimated CBR values for pavement design purposes.

[0039] In another embodiment herein, the method that has developed correlations between the CBR and DCPI based on data collected during both pre-monsoon and monsoon periods and, under laboratory conditions of soaked and unsoaked states, enhances the reliability of the correlations across different environmental conditions. The method establishes soil-specific correlations between CBR values obtained in the laboratory and DCPT measurements from field tests for silty sand (SM) and clayey silty sand (SC-SM) improves the accuracy and applicability of soil strength evaluations.

[0040] In one embodiment herein, the correlations is developed between the CBR and DCPI. Mostly, common relationships are developed by many researches for both granular and cohesive soils, which are not advised as they are not soil specific and region specific and the tests are not conducted during monsoon season. Hence, the soil specific correlations need to be developed for different soils. A correlation between CBR and DCPI for silty sand and clayey silty sand is established in south asia, which is situated in the eastern coastal region of peninsular india, where no soil specific correlations were developed.

[0041] According to another exemplary embodiment of the invention, FIG. 2 refers to a schematic view of a dynamic cone penetrometer 200. In one embodiment herein, the dynamic cone penetrometer 200 comprises a handle 202, a hammer 204, an upper rod 206, an anvil 208, a pin 210, an upper attachment 212, a drive rod 214, a scale 216, a foot 218, and a disposable cone 220. In one embodiment herein, the handle 202 is positioned on top of the dynamic cone penetrometer 200. The handle 202 is configured to enable the user to hold and operate the dynamic cone penetrometer 200.

[0042] In one embodiment herein, the hammer 204 is positioned beneath the handle 202. The hammer 204 is heavy weight that is dropped from a specific height to drive the disposable cone 220 into the ground surface from the desired location. In one embodiment herein, the anvil 208 is configured to impacts with the hammer 204 to drive the disposable cone 220 into the soil. Furthermore, the anvil 208 is configured to absorb the impact force and directs it down the end. In one embodiment herein, the drive rod 214 extends downward from the anvil 208 to the tip of the disposable cone 220. The drive rod 214 is configured to transmit the force from the hammer 204 to the disposable cone 220.

[0043] In one embodiment herein, the disposable cone 220 is positioned at the bottom of the drive rod 214. The disposable cone 220 is configured to penetrate the soil when the hammer 204 impacts the anvil 208. The disposable cone 220 possess a standardized angle of 60 degrees and size to ensure consistent results. In one embodiment herein, the scale 216 is marked along the length of the drive rod 214. The scale 216 is configured to measure the penetration depth of the disposable cone 220 after each hammer blow.

[0044] In one embodiment herein, the contemporary examination to establish the relationship between CBR and DCPI for silty sand and clayey silty sand. The soil samples for the contemporary examination are collected at varying depths near ground level, at least 0.5 meter below ground level and 1 meter below ground surface from 23 trials pits each at the eastern coastal region of peninsular india. The dynamic cone penetration test (DCPI) and core cutter test are performed in the field. The DCP test is conducted as per American Society for Testing and Materials (ASTM) D6951/D6951M-09. The DCPT is configured to conducted till the tip of the cone penetrates into the soil up to the depth of one meter using an extension rod by giving blows and the penetration depth is recorded during the operation through which DCPI in millimeter per blow is calculated.

[0045] The field density is also determined using the core cutter method as per Indian Standard (IS):2720 at the same test location where the DCP tests are conducted. DCP tests are performed during the pre-monsoon and monsoon periods which represents the CBR tests in unsoaked and soaked conditions respectively. The CBR tests are performed by simulating field conditions in the laboratory by compacting the soil to natural moisture content and field density. The soil samples are collected from the trail pits at different depths from various locations are taken to the laboratory and various index and engineering properties such as specific gravity, grain size distribution, atterberg limits, Natural moisture content and CBR are determined by conducting the test as per IS-2720. The obtained result of in-situ and laboratory investigation carried out are presented below in Table.1.

[0046] Table. 1

[0047] In one embodiment herein, the dynamic cone penetrometer (DCP) 200 is configured to enable the user to place the dynamic cone penetrometer 200 on the representative location for testing. Initially, the user places the DCP 200 equipment vertically over the test site, and ensure the disposable cone 220 is in contact with the ground surface. The user is configured to record the initial reading from the depth measurement scale on the drive rod 214. This is the starting point for measuring penetration depth. Next, the user lifts the hammer 204 to certain height and release it to fall freely onto the anvil 208.

[0048] The hammer 204 impact drives the cone tip into the soil. After each hammer blow, record the depth of penetration using the scale 216. Calculate the penetration depth per blow, often referred to as the Dynamic Cone Penetration Index (DCPI), which is expressed in millimetres per blow. Record all measurements systematically, including the number of blows and corresponding penetration depths. Analyze the recorded data to determine the soil strength and compaction properties. Higher penetration per blow indicates weaker or less compacted soil, while lower penetration per blow indicates stronger or more compacted soil.

[0049] In one embodiment, Table 1 depicts various soil properties and their influence on soil strength and behavior under different moisture conditions. The table 1 includes soil types such as silty sand (SM) and clayey silty sand (SC-SM). It shows the Dynamic Cone Penetration Index (DCPI) measured in millimeters per blow during the pre-monsoon period, indicating soil compaction and strength. The California Bearing Ratio (CBR) in an unsoaked condition represents the subgrade soil strength. Additionally, the DCPI (mm/blow) is measured during the monsoon period. Finally, the CBR in a soaked condition represents the soil's strength when it is soaked.

[0050] According to another exemplary embodiment of the invention, FIG. 3 refers to a flowchart 300 of the determination of the subgrade strength of silty sand and clayey silty sand. At step 302, the user selects the desired location to conduct the DCPT for silty sand and clayey silty sand. At step 304, the user performs an experimental investigation of the DCP, checking it for any damages or wear and ensuring it is calibrated correctly. This is followed by collecting soil samples from the desired location to be tested in both the laboratory investigation (308) and the field (in situ) investigation (306).

[0051] At step 310, the field investigation 306 is conducted by using the dynamic cone penetration test (DCPT) 310 in suitable environmental regions such as pre-monsoon seasons and monsoon seasons. At step 308, the laboratory investigation 308 is performed by conducting California bearing ratio test (CBR) 316 and further various soil properties are determined. The soil properties include specific gravity, atterberg’s limit, grain size distribution, field moisture content, and field density. The CBR test is conducted under two conditions, which include a soaked condition 322 and an unsoaked condition. The CBR samples are compacted to field moisture content and field dry density (FMC-FDD) 320.

[0052] At step 324, the development of correlation equation between CBR and DCPI. The CBR is configured as a measure of soil resistance to penetration, often used to evaluate the subgrade strength for road and pavement construction. The DCPI measures the penetration per blow of a dynamic cone penetrometer and provides a quick assessment of penetration resistance of soil in the field. The development of a correlation equation between CBR and DCPI aims to provide a reliable method for estimating CBR values from DCPI measurements, thereby facilitating quicker and more efficient soil evaluations test to enhance the reliability of the estimated CBR valves for pavement design purposes.

[0053] According to another exemplary embodiment of the invention, FIG. 4A refers to a graphical representation 402 of dynamic cone penetration index (DCPI) against CBR during a pre-monsoon season. In one embodiment herein, the x-axis represent the DCPI (Dynamic Cone Penetration Index) values obtained from the field tests during the pre-monsoon season. The higher DCPI values generally indicate weaker soil conditions. The Y-axis represents the CBR (California Bearing Ratio) values determined from the laboratory tests performed on soil samples collected during the pre-monsoon season. The higher CBR values indicate better subgrade soil strength. The graph represent a scatter of data points, with each point representing the DCPI value measured in the field for a specific soil sample and its corresponding CBR value determined in the laboratory.

[0054] The DCPI values increase (indicating weaker soil), the corresponding CBR values decrease (indicating lower subgrade strength of soil). In one embodiment herein, the graph would be specific to the pre-monsoon season. During the pre-monsoon season, the soil is likely drier and less prone to moisture variations compared to the monsoon season.

[0055] According to another exemplary embodiment of the invention, FIG. 4B refers to a graphical representation 404 of the DCPI against CBR during monsoon season. In one embodiment herein, the X-axis represents the DCPI values obtained from field tests using the Dynamic Cone Penetration Test (DCPT) during the monsoon season. The higher DCPI values indicate weaker soil conditions. The Y-axis represents the CBR values determined from laboratory tests performed on soil samples collected during the monsoon season. The higher CBR values indicate better subgrade strength of the soil. The graph shows a scatter of data points, where each point represents the DCPI value measured in the field for a specific soil sample and its corresponding CBR value obtained in the laboratory.

[0056] In one embodiment herein, the dotted line is fitted through the data points, which suggests a generally positive correlation between DCPI and CBR, which means that as the DCPI values increase (weaker soil), the corresponding CBR values tend to decrease (lower subgrade soil strength). The graph focuses on data collected during the monsoon season. Due to increased moisture content, soils during the monsoon season are generally weaker and more susceptible to variations compared to the pre-monsoon season. The result in a more scattered data distribution compared to a pre-monsoon DCPI vs CBR plot. Other factors like variations in moisture content within the monsoon season might influence the CBR values.

[0057] According to another exemplary embodiment of the invention, FIG. 4C refers to a graphical representation 406 of the DCPI against CBR during both pre-monsoon and monsoon seasons. In one embodiment herein, the X-axis represents the DCPI values obtained from field tests using a Dynamic Cone Penetration Test (DCPT). The Y-axis represents the CBR values determined from laboratory tests conducted on soil samples collected during corresponding seasons. The higher CBR values signify better subgrade strength of the soil.

[0058] In one embodiment herein, the graph indicates the importance of considering seasonal variations when evaluating the penetration resistance of soils using DCPI. During the monsoon season, DCPI measurements might need to be used cautiously, potentially in conjunction with other soil characterization techniques, to account for the influence of moisture content on CBR.

[0059] Table. 2
Soil Season Correlation equation R² Model
SM and SC-SM Pre-monsoon CBR = 492.45(DCPI)-1.286 0.95 Power
SM and SC-SM Monsoon CBR= -7.174ln(DCPI)+31.434 0.93 Logarithmic
SM and SC-SM Pre-monsoon and
Monsoon CBR = 1036.6(DCPI)-1.521 0.93 Power

[0060] The Correlation equations between CBR and DCPI are developed separately for pre-monsoon and monsoon seasons, as well as combined for both seasons. The coefficient of determination (R²) is nearly the same in all three cases. Therefore, the combined relationship between CBR and DCPI, developed during both pre-monsoon and monsoon periods, is adopted.

[0061] Table. 3

[0062] Table. 4
CBR (%) Permissible Variation in
CBR value Permissible error
(%)
5 ±1 Up to 20
5-10 ±2 20-40
11-30 ±3 10-30

[0063] In one embodiment herein, the developed correlation equation is validated using DCP and CBR test data obtained from tests conducted again in 12 trial pits at ground level, 0.5m below ground level, and 1m below ground level at the same site during pre-monsoon and monsoon seasons. The percentage error between the actual CBR and the predicted CBR is calculated. It is observed that the percentage error falls within an acceptable range according to IRC-37 standards, as presented in Table 4.

[0064] Numerous advantages of the present disclosure may be apparent from the discussion above. In accordance with the present disclosure is method for determining California bearing ratio (CBR), is disclosed. The proposed method develops correlations between DCPI and CBR based on the data collected during both pre-monsoon and monsoon periods and, under laboratory conditions of soaked and unsoaked states, enhances the reliability of the correlations across different environmental conditions.

[0065] The proposed method conducts DCPI tests up to a depth of 1000mm with a typical highway penetration depth of 900 mm using an extension rod, ensuring that the method is applicable for depths relevant to highway construction and maintenance. The proposed method establishes soil-specific correlations between CBR values obtained in the laboratory and DCPI measurements from field tests for silty sand (SM) and clayey silty sand (SC-SM) improves the accuracy and applicability of soil strength evaluations.

[0066] The proposed method performs DCP tests in the field during varying seasons, and conducting CBR tests in the laboratory under different moisture conditions. The proposed method utilizes data collected from different depths in the field to ensure that the correlations developed are robust and applicable across varying soil conditions and depths.

[0067] The proposed method incorporates a field density test using the core cutter method for the collection of undisturbed soil samples. The proposed method within controlled standardized conditions for compacting soil samples to match field moisture content (FMC) and field dry density (FDD) ensures the consistency and accuracy of soil-specific correlations for CBR samples.

[0068] 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 determining California bearing ratio of silty sand and clayey silty sand subgrades, comprising:
conducting a dynamic cone penetration test (DCPT) at selected locations for silty sand and clayey silty sand;
measuring a penetration depth for each cumulative weight drop of hammer while conducting the DCPT;
collecting the representative soil samples from selected locations corresponding to a desired depth;
performing laboratory tests on the collected soil samples to determine the specific gravity, grain size distribution, Atterberg limits, field moisture content, and field density;
conducting a California bearing ratio (CBR) test on the collected soil samples in the laboratory under two conditions; and
establishing a correlation between the DCPI obtained from the DCPT measurements and the CBR value determined from the laboratory CBR test to enhance the reliability of the estimated CBR values for pavement design purposes.
2. The method as claimed in claim 1, wherein the correlation is established based on the DCPT measurements obtained from depths up to 1000 mm.
3. The method as claimed in claim 1, wherein the DCPT is conducted during pre-monsoon and monsoon seasons to stimulate for seasonal variations in soil conditions.
4. The method as claimed in claim 1, wherein the CBR tests are performed under two conditions, which include unsoaked and soaked conditions to stimulate different moisture states of the soil.
5. The method as claimed in claim 1, wherein the laboratory CBR test is conducted on the soil sample compacted to a density corresponding to the field moisture content and field dry density (FMC-FDD).
6. The method as claimed in claim 1, wherein the correlation between the CBR values and the DCPI measurements provide a quick, economic, and accurate means for evaluating the subgrade soil strength of silty sand (SM) and clayey silty sand (SC-SM) in the desired location.
7. The method as claimed in claim 1, wherein the correlation incorporates a field density test using a core cutter method performed at the desired location and corresponding depth of the desired DCPT measurements.
8. The method as claimed in claim 1, wherein the atterberg limits include liquid limit and plastic limit of soil are determined.
9. The method as claimed in claim 1, wherein the collected soil sample from different depths in the field to enhance the accuracy and applicability of the developed correlations.