Dynamic Cone Penetration Index Research Articles

Hammer weight and dropping height effects on dynamic response in densely-packed geo-materials

This study aims to investigate the dynamic cone penetration index (DCPI) and dynamic responses during instrumented dynamic cone penetration test at fixed-end condition (e.g., dense layer). Several types of hammer weights and heights at fixed potential energy (45.13 N∙m) is applied on the instrumented dynamic cone penetrometer (IDCP) tests. Test results show that the instrumented dynamic cone penetration index (IDCPI) is proportional to the DCPI with various gradients lower than 1.0 due to the influence of hammer weight on drivability. Dynamic responses change with respect to the end boundary condition (e.g., dense or loose layer) and location at the head or tip. In addition, the transferred energy varies with respect to the end boundary condition, location, hammer weight and height. For layer characterization, the end boundary condition should be primarily considered as well as hammer weight and height regarding drivability.

Detection of roadbed layers in mountainous area using down-up-crosshole penetrometer and ground penetrating radar

The characteristics and depths of the old roadbed layers must be assessed for the serviceability and rehabilitation of aging road pavements. This study’s objective is to detect roadbed layers in mountainous areas using the obtained stiffness profile and ground penetrating radar (GPR) results. Down-up-crosshole penetrometer (DUCP), GPR, and light falling weight deflectometer (LFWD) tests were conducted to determine the overlay, surface, base, subbase, antifrost, and subgrade layers. The results show that the dynamic cone penetration index DCPI, shear modulus calculated by the shear wave velocity, and GPR image capture each layer. The elastic modulus estimated by the shear modulus is corrected by considering the strain influence factor and matches the LFWD modulus, despite the ranges of values differing owing to the disparate strain level. Therefore, the DUCP can be applied to roadbeds in mountainous areas to assess the stiffness at each layer as well as to detect the layer interface.

Assessing strength properties of stabilized soils using dynamic cone penetrometer test

Abstract The subgrade soil layer is the most essential part of the pavement system. Many pavement failures can be associated with subgrade weak strength and stiffness qualities. Therefore, it is necessary to strengthen this layer before building the other pavement layers. One of the essential methods utilized to enhance the engineering characteristics of this layer is soil stabilization. Stabilization methods are many and varied, but chemical and mechanical stabilization are the most common. This research aims to evaluate the strength of stabilized soils by using a dynamic cone penetration (DCP) test. To achieve this aim, subgrade soil was provided from a roadway project in Kerbala city and stabilized with 2.5 and 5% of Portland cement by weight of the dry soil. Then, the cemented subgrade soil was reinforced with 6 and 12 mm of polypropylene discrete fiber. The fiber was added to the soil with the following contents: 0.5, 1, and 2%. The characteristics of stabilized soils were evaluated by determining three parameters: dynamic cone penetration index (DCPI), in-situ California bearing ratio (CBR), and bearing capacity obtained from the DCP test. The results showed that when Portland cement was increased from 0 to 2.5% and then to 5% by weight of the dry soil, the DCPI value gradually decreased while increasing both CBR and bearing capacity. However, adding 6 and 12 mm fiber contents (0.5, 1, and 2) to the cement–sand mixture containing 2.5 and 5% cement led to increased DCPI and a gradual decrease in CBR and bearing capacity. Also, the results showed that the DCPI for a 12 mm fiber is lower than that for 6 mm fibers, while the CBR and bearing capacity for a 12 mm fiber are greater than those of 6 mm fibers for all ratios. Accordingly, the results of the DCP tests showed that the most significant support for the soil is obtained when the soil is stabilized using 5% cement with 12 mm of fiber by weight of dry soil.

Application of automated cone penetrometer for railway investigation using correlations with DCPI and deflection modulus

Portable in-situ devices have been used for characterizing low accessible field, such as the railway subgrade. In this study, the automated cone penetrometer (ACP) was designed for the application on the railway subgrade. ACP is composed of the cone tip, driving rod, and hydraulic hammer system. The hydraulic motor lifts and drops the 294.3 N hammer from a height of 200 mm such that the potential energy of 58.9 N m impacts the driving rod. The N-value (NACP) from the ACP test was compared with the dynamic cone penetration index (DCPI) from the dynamic cone penetrometer (DCP) test. The test results show that the NACP and DCPI profiles show opposite trend owing to the inverse concept of the unit. From the correlation of DCPI and NACP, the limitation of DCPI reveals owing the minimum manually measured value of 1 mm/blow. Additionally, the evaluation of the deflection modulus (EFWD) using NACP is more efficient than that using DCPI. Based on the result of this study, we suggest that ACP can be used for strength and stiffness evaluation of railway subgrade rapidly and reliably.

Development of Prediction Models for Performance of Flexible Pavements in Kansas with Emphasis on the Effects of Subgrade and Unbound Layers

This study resulted from the need for better consideration of subgrade and unbound layers on the performance of flexible pavements in Kansas. Thus, the main objective was to develop pavement performance prediction models with emphasis on the effects of subgrade and unbound layers. To this end, pavement distress data, which were collected over several years across the state of Kansas, including rutting, fatigue cracking, transverse cracking, roughness and core analysis, served as the input data into statistical models. The effects of subgrade and unbound layers were represented by the corresponding results of dynamic cone penetrometer (DCP) tests and thickness of the unbound layer. In addition, traffic volume was represented by average annual daily truck traffic (AADTT). Multiple statistical analyses identified positive correlations of dynamic cone penetration index (DPI) and rate of total rutting, and DPI and percent of good core. Negative correlation was discovered between DPI and fatigue cracking code one, and DPI and percent of poor core. AADTT was positively correlated with transverse cracking codes one and two while it had no correlation with transverse cracking code zero. Thickness of the unbound layer was negatively correlated with pavement roughness and percent of poor core, while it was positively correlated with the percent of good core. Finally, the recommendation for minimum acceptable value of California bearing ratio (CBR) was provided based on the correlation between DPI and rate of change of rutting code. The recommendation enables the selection of a CBR value based on the number of years required for unit increase in the rutting code.

Large-scale spatial characterization and liquefaction resistance of sand by hybrid bacteria induced biocementation

Microbially induced calcite precipitation (MICP) has received greater attention of geotechnical engineers recently as a potentially effective and sustainable approach for biocementation of sands. Present study investigates spatial variability and synergistic effects of bacterial hybrids of Sporosarcina (S.) pasteurii and Bacillus (B.) sphaericus for sand biocementation which is important to explore to stimulate real field conditions where multiple urease producing can be present in soil environment. Large-scale testing was conducted in rectangular tank (135 cm × 113 cm × 65 cm) filled with Narmada sand (1.21 Ton), treated using bio-chem distribution system consisting of bioreactor, chemical mixer, circulation tank, injection pipes, treatment tank, and drainage outlets. The design of bioreactor and slotted injection pipes are the major novel aspect of this study for on-site bacterial cultivation and uniform calcite precipitation throughout the treatment depth to increase liquefaction resistance of sand which was not investigated in previous large-scale testing studies. Bacterial hybrid was first cultivated, then inoculum of 10 L was prepared, and finally, 200 L of bacterial solution was cultivated in bioreactor. Sand was bioaugmented with hybrid bacteria in tank, subsequently injected 0.50 M urea and cementation solution periodically up to 8 days. Biosparging was also implemented for 10–12 h daily using air pumps to ensure aerobic conditions. During the treatment, pH, electrical conductivity (EC), and total dissolved solids (TDS) were measured periodically as indicators of biogeochemical reactions occurring during biotreatment. Dynamic cone penetration tests (DCPTs) were performed and DCPT-blows up to 30 cm depth were measured at 20 locations. Contours of dynamic cone penetration index (DCPI) and calcite precipitation were used to assess spatial variability of biocementation. Average DCPT blow count for untreated sand was 5, but it increased up to 50 with 10.6% calcite content, for 30 cm penetration. The DCPT results showed significant improvement in liquefaction resistance. Biocemented samples were collected from various locations to measure calcite content and conduct SEM. Overall, the large-scale testing showed effective and substantial biocementation of sand using the cultivated hybrid bacteria and bio-chem distribution/air sparging system developed in this study. The spacing of injection points and the amounts of injection biotreatment solutions can be optimized to achieve uniform, adequate, and cost-effective biotreatment under actual field applications.

Prediction of CBR using dynamic cone penetrometer index

Nowadays, construction of new roads and upgradation of existing roads are booming as a part of infrastructural development in India. Subgrade strength plays an important role in the design and construction of pavement. California bearing ratio (CBR) test is used to measure the strength of subgrade and most of the highway agencies design the pavement section using CBR value of the subgrade. The conduction of CBR test consumes more effort and time as it involves soil sampling, preparation of soil specimens, soaking for 96 h and testing. Also, the laboratory assessment of CBR does not simulate the in-situ soil properties (mainly moisture and density) and the laboratory CBR sometimes may be higher than the CBR of the soil under in-situ condition as compaction is carried out in a confined rigid mould. In this study, dynamic cone penetrometer (DCP) index is used to predict the subgrade CBR values. A total of eight soil samples were collected from two different sites and the various engineering properties are determined. To know the effect of density, moisture content, fines content and CBR on the dynamic cone penetration index (DCPI), a series of laboratory compaction tests, CBR tests and DCP tests are conducted. The available correlations are verified for their predictability of CBR values and the correlations suitable for the local soils are recommended.

Subgrade assessment using automated dynamic cone penetrometer to manage geo-infrastructures

For the efficient management of geo-infrastructures in the field, engineering properties of the subgrade should be reliably and rapidly investigated. The objective of this study is to estimate and compare the strength and stiffness parameters of subgrades using portable in-situ devices. An automated dynamic cone penetrometer (ACP), dynamic cone penetrometer (DCP), and light falling weight deflectometer (LFWD) are adopted and applied at nine points of soft ground in South Korea. The Nvalue from the ACP (NACP), which efficiently assesses the relatively deep subgrade, is correlated with the dynamic cone penetration index (DCPI) and dynamic deflection modulus (Evd). Test results show that the DCPI and Evd can be estimated in terms of NACP. In particular, the relationship between Evd and NACP is improved when the strain influence factor of the target ground is considered. For the assessment of strength and stiffness parameters, the California bearing ratio (CBR), relative density (Dr), internal friction angle (φ), and elastic moduli determined by the plate loading test (PLT), soil stiffness gauge (SSG), falling weight deflectometer (FWD) are estimated using NACP. The ACP test with the relationships between engineering parameters and NACP may be an effectively method to assess the overall characteristics of the subgrade.

Comparative Study on Estimation Methods of Dynamic Resistance Using Dynamic Cone Penetrometer

Dynamic resistance, which can be used to express strength in the unit of stress and improve the reliability of the dynamic cone penetration test (DCPT), has been estimated by numerous methods. This study aims to compare different dynamic resistance estimation methods by using an instrumented dynamic cone penetrometer (IDCP). DCPTs are conducted using a standard dynamic cone penetrometer (DCP) and IDCP in the laboratory and field. Dynamic responses are obtained from the strain gauges and an accelerometer installed at the cone tip of the IDCP. The test results show that dynamic resistance is more efficient in distinguishing profiles than the dynamic cone penetration index. Among the methods to estimate the dynamic resistance at the cone tip, the force-velocity integration method and force integration method are more related to the conventional dynamic resistance considering the potential energy of the hammer than the force squared integration method. Additionally, the dynamic resistance estimated for a longer time period is more reliable, particularly for small driving rod lengths. Regarding the limitation of the dynamic response from an accelerometer in a previous study, the force-based dynamic resistance estimated for a longer time period can be used as the most reliable approach for further soil strength characterization.

Instrumented Cone Penetrometer for Dense Layer Characterization.

Subsurface characterization is essential for a successful infrastructure design and construction. This paper demonstrates the use of an instrumented cone penetrometer (ICP) for a dense layer characterization at two sites. The ICP consists of a cone tip and rods equipped with an accelerometer and four strain gauges, which allow dynamic driving, in addition to quasi-static pushing of the cone. The force and velocity of the cone are measured using the ICP instrumentation and compared with the N value, dynamic cone penetration index, and static cone resistance. A strong correlation has been observed between the total cone resistance estimated from the ICP and the dynamic cone penetration index and static cone resistance. After the correction of the dynamic cone resistance effect, the static component of the total cone resistance can be used as an alternative to a static cone resistance. This novel approach of soil resistance estimation using the ICP may be useful for dense layer characterization.

Influence of Geosynthetic Reinforcement on Unpaved Roads Based on CBR, and Static and Dynamic Cone Penetration Tests

Dynamic cone penetrometer has been used widely as a pavement evaluation technique for many years. Unpaved roads constructed on weak soil subgrade are frequently subjected to severe damage and hence, they require regular maintenance and repair. One of the main stabilization methods of improvement of the serviceability of these roads is to reinforce them with geosynthetics (geotextile/geogrid). Field experiments were conducted on unpaved test sections reinforced with geotextile and geogrid, with the potential use of dynamic cone penetrometer (DCP) and digital static cone penetrometer (SCP) to assess benefits of geotextile and geogrid reinforcement. Laboratory California bearing ratio (CBR) tests were also conducted on subgrade–aggregate section and the effect of geosynthetic reinforcement was investigated by placing the reinforcement layer at the interface of the base course layer and weak subgrade. Digital SCP was used to measure the load–displacement behavior of geosynthetic-reinforced test section in the field. The field test results of DCP were expressed in terms of dynamic cone penetration index (DCPI, mm/blow), defined as the penetration depth of the cone per hammer blow and recorded along with the depth profile. A decrease in DCPI value was observed for the reinforced test sections as compared to the unreinforced test section. DCP results were able to detect transition zone and significant change in the strength of unpaved test section along with penetration depth. The field results indicate the greater resistance to penetration in the geosynthetic-reinforced test section and the penetrometer resistance increases with the depth. Higher penetration resistance offered by the geotextile has more contribution to the performance improvement of the test section.

Unpaved test sections reinforced with geotextile and geogrid

Geotextile and geogrid are used routinely to reinforce the unpaved roads to enhance the serviceability and stability of these roads. Field performance studies were conducted on unpaved test sections reinforced with geotextile and geogrid to demonstrate how geosynthetics improve the test section performance using dynamic cone penetrometer (DCP). The influence of geosynthetic reinforcement was investigated by placing the reinforcement layer at subgrade-base interface, thus helps to achieve more sustainable unpaved test section. Direct shear tests were conducted on soil samples reinforced with geotextile and geogrid to investigate the improvement in shear strength of geosynthetic reinforced soil. The results of DCP test were demonstrated as dynamic cone penetration index value (DCPI, mm/blow). DCPI values were observed in range from 1 to 7 mm/blow, corresponding to 500 mm depth of penetration for unreinforced and geogrid-reinforced test section and 312 mm depth of penetration for geotextile-reinforced test section respectively. A decrease in DCPI value was observed for the geosynthetic-reinforced unpaved test section as compared to the unreinforced unpaved test section. Direct shear test results shows a significant improvement in the shear strength of soil samples reinforced with geotextile.

Long-Term Performance of Rural Roads Reinforced with Coir Geotextile – A Field Study

ABSTRACT India has one of the largest road networks in the world, aggregating to about 56 lakh km at present. At sites with inadequate CBR, problems of excessive rutting are very common. In order to overcome this ground improvement techniques such as inclusion of coir geotextile is a good option. Coir geotextiles are manufactured with coir fibers, extracted from the husk of coconut, and are more durable than other natural fibers due to high lignin content. Construction of pavements strengthened with coir geotextiles makes it cost-effective and eco-friendly. In this paper, the results of the performance study conducted on five coir geotextile reinforced and unreinforced roads in different parts of Kerala, after three to 6 years of construction are reported. Coir geotextile had been placed in between subgrade and sub base. The performance was evaluated by conducting Benkelman Beam Deflection (BBD), Field CBR and Dynamic Cone Penetration (DCP) test on reinforced and unreinforced roads. A reduction in characteristic deflection thereby decrease in bituminous Macadam overlay, decrease in DCP Index and improvement in in-situ CBR values ranging from 22% to 178% were obtained for roads on all types of soil. A correlation was also developed between field CBR and field DCPI.

Assessing subgrade strength using an instrumented dynamic cone penetrometer

Subgrade strength is an important aspect to be considered when designing unsurfaced roads and working platforms for pavement structures. Furthermore, dynamic cone penetration tests are used to characterize the subgrade strength. However, the results of dynamic cone penetration tests, including the penetration depth per blow, can be affected by transferred energy and the verticality of the cone penetrometer. The objective of this paper is to characterize the subgrade strength using an instrumented dynamic cone penetrometer (DCP). The instrumented DCP includes a load cell and an accelerometer, located on the cone tip, and measures the dynamic responses of force and velocity over elapsed time. Weathered soil is compacted with three different dry unit weights in a square-shaped container for lab-scale dynamic cone penetration tests. Using instrumented and standard DCPs, several dynamic cone penetration tests are performed, and the dynamic cone penetration index (DCPI) is recorded along the depth profiles. Based on the dynamic responses at the cone tip of the instrumented DCP and the principles of energy conservation, the dynamic cone resistance is suggested as a new strength index. The experimental results show that the dynamic cone resistance increases with the depth of the instrumented DCP, providing a reliable subgrade strength profile in the soil. In addition, the correlation between the DCPI obtained from the instrumented DCP and the dynamic cone resistance suggests that the dynamic cone resistance is more sensitive than the DCPI for stiff soil. Based on the correlation values of the dynamic cone resistance obtained from the instrumented DCP, the internal friction angle and California bearing ratio values can be estimated with a high degree of reliability. This study demonstrates that use of the instrumented DCP may be a promising in situ testing method for the reliable characterization of subgrade strength.

Energy correction of dynamic cone penetration index for reliable evaluation of shear strength in frozen sand–silt mixtures

Previously, in situ tests have been conducted in cold regions since infrastructures such as pipelines have been actively built on frozen ground. However, the engineering properties such as shear strength have not been directly evaluated from in situ tests. The objective of this study is to correlate the shear strength of frozen soils determined by the direct shear tests with the dynamic cone penetration index (DCPI) measured by the instrumented dynamic cone penetrometer (IDCP). The IDCP, which incorporates strain gauges and an accelerometer to measure the energy transferred to the cone tip, is used to estimate the energy-corrected dynamic cone penetration index (energy-corrected DCPI). The direct shear apparatus and the calibration chamber for the IDCP application test are placed in the freezer. The sand–silt mixtures are prepared in the shear box and the calibration chamber at the degree of saturation of 10% and relative density of 60%. Vertical confining stresses are applied to the specimens during the freezing and strength evaluating phases, such as direct shearing or penetrating the IDCP, to determine the effect of the vertical confining condition. The experimental results show that the shear strength of the frozen soils increases in a nonlinear parabolic shape with an increase in the vertical confining stress. Furthermore, the vertical confining stress during the strength evaluating phase has more influence on the strength than that during the freezing phase because the degree of saturation of specimens is low. As the energy transferred to the cone tip is affected by the soil conditions under the cone tip, the energy-corrected DCPI, which is inversely proportional to the shear strength, has a better relationship with the shear strength. This study demonstrates that the energy-corrected DCPI can be effectively used for the evaluation of the shear strength of frozen soils.

Assessing the Effect of Density and Water Level on the Degree of Compaction of Sand Using Dynamic Cone Penetration Test

Saudi Arabia has witnessed unparalleled development in all types of construction, especially in eastern Saudi Arabia where the major oil and petrochemical industries are located. The major projects are mostly located on sandy soil, and it is difficult to assess the physical properties of this soil using conventional methods. Consequently, laboratory and field studies were conducted to evaluate the density of sandy soil utilizing dynamic cone penetration test (DCPT). The laboratory study was conducted on sand specimens prepared with different relative densities (40%, 60% and 90%). Additionally, the effect of the level of water table on DCPT values was investigated. The density of soil at two field sites was assessed by using DCPT and nuclear gauge. Test results indicated that an increase in the dry density and shear strength was associated with a decrease in the dynamic cone penetration index. Further, the variation in the water table level had a significant impact on DCPT results due to the changes in the effective stress. The DCP resistance for fully drained sand increased significantly by as much as 170% compared with the fully submerged or dry sand, due to the development of negative pore water pressure. Further, the results of this investigation have shown that DCPT is an effective and reliable tool to assess the degree of compaction of sandy soils. Reliable correlations between density, relative density and degree of compaction of sandy soils have also been developed.

Application of a nondestructive method to evaluate the active layer in a cold region

To provide a safe transportation system in an extremely cold region, evaluation needs to be conducted of the thickness and the volumetric water content of the active layer, as they significantly affect frost heave. The objective of this study was to evaluate the dielectric constant ( κ ) of the active layer using ground-penetrating radar (GPR) and a dynamic cone penetrometer (DCP); this evaluation was then used to estimate the thickness and the volumetric water content of the active layer. A field located in midwest Alaska was selected as the study site. A GPR survey and two DCP tests were conducted on the surface of the ground, and the ground temperature was measured. From the GPR survey, travel times of the electromagnetic wave in the active layer were obtained. In addition, the thickness of the active layer was determined by using the dynamic cone penetration index (DCPI) and ground temperature. By using the travel time and travel distance of the electromagnetic wave in the active layer, dielectric constants were calculated as 26.3 and 26.4 for two DCP points. From the mean dielectric constant, the volumetric water content was estimated to be 40%~43%, and the thickness of the active layer was evaluated along the GPR survey line. The spatial-scaled GPR image showed that the thickness of the active layer varied from 520 mm to 700 mm due to the presence of a puddle, which accelerated the heat exchange. The results show that evaluation of the dielectric constant using the GPR survey and the DCP test can be effectively used to estimate the thickness and the volumetric water content of the active layer.

Estimation of elastic wave velocity and DCPI distributions using outlier analysis

The reliability of a geostatistical method depends on the probability distribution of the measured values; unreasonable data should be removed. The objective of this study was to suggest a technique for predicting the distribution of geotechnical engineering data, namely the elastic wave velocity and the dynamic cone penetration index (DCPI), while eliminating biased values through outlier analysis. The refraction survey was applied to obtain elastic wave signals at four profiles, with lengths of 90 m, 20 m, 20 m, and 20 m, in the Geohwa Mountains, Korea. The Dynamic Cone Penetration Test (DCPT) was also performed at 15 sites to suggest a reference value of the objective area, and the measured values were converted into the DCPI. To determine the range of the biased value for the elastic wave and DCPI, the cross validation and the Generalized Extreme Value (GEV), that is, the Gumbel, Frechet, and Weibull functions, were selected, and confidence levels of 10%–90% were determined. A total of 8 and 2 data items were removed from the measured elastic wave velocity and DCPI after considering the confidence level through outlier analysis. Finally, contour maps of the elastic wave velocity and DCPI were created, and the enhancement was verified using the calculated performance ratio. The results suggest that outlier analysis based on cross validation and the GEV can provide highly reliable distributions of geotechnical engineering data with implementing geostatistical methods.

Analyses of GPR signals for characterization of ground conditions in urban areas

Ground penetrating radar (GPR) is applied for the characterization of the ground conditions in urban areas. In addition, time domain reflectometry (TDR) and dynamic cone penetrometer (DCP) tests are conducted for the accurate analyses of the GPR images. The GPR images are acquired near a ground excavation site, where a ground subsidence occurred and was repaired. Moreover, the relative permittivity and dynamic cone penetration index (DCPI) are profiled through the TDR and DCP tests, respectively. As the ground in the urban area is kept under a low-moisture condition, the relative permittivity, which is inversely related to the electromagnetic impedance, is mainly affected by the dry density and is inversely proportional to the DCPI value. Because the first strong signal in the GPR image is shifted 180° from the emitted signal, the polarity of the electromagnetic wave reflected at the dense layer, where the reflection coefficient is negative, is identical to that of the first strong signal. The temporal-scaled GPR images can be accurately converted into the spatial-scaled GPR images using the relative permittivity determined by the TDR test. The distribution of the loose layer can be accurately estimated by using the spatial-scaled GPR images and reflection characteristics of the electromagnetic wave. Note that the loose layer distribution estimated in this study matches well with the DCPI profile and is visually verified from the endoscopic images. This study demonstrates that the GPR survey complemented by the TDR and DCP tests, may be an effective method for the characterization of ground conditions in an urban area.

Strength and stiffness assessment of railway track substructures using crosshole-type dynamic cone penetrometer

To ensure safe train services, an effective method is required for the characterization of the strength and stiffness of railway track substructures. In this study, a crosshole-type dynamic cone penetrometer (CDP) is developed to characterize the strength by the crosshole-type dynamic cone penetration index (CDPI) and stiffness by the shear wave velocity (Vs). To verify the Vs obtained using the CDP test, the Vs obtained by both CDP and bender elements are compared in a chamber test. In addition, for the characterization of the railway track substructures, field tests are conducted. The chamber test shows that the Vs obtained using the CDP are almost the same as those obtained by bender elements. In field tests, the CDPI and the Vs are profiled along the depth, the including ballast, sub-ballast, and subgrade layers, which are identified by ground penetrating radar surveys. As the CDPI is highly correlated to the Vs, the stiffness characteristics are considered to be reasonable and can be simply estimated using the CDPI. This study demonstrates that the CDP test can be used for the evaluation of the strength characteristics and small strain elastic properties of the track substructures.