Dynamic Cone Penetration Test Research Articles

Subgrade stabilisation mixtures with EAF steel slag: an experimental study followed by field implementation

ABSTRACT This study investigates the viability of using electric-arc-furnace steel slag (EAF SS)-blast furnace slag (BFS) and EAF SS-Class C fly ash (FA) mixtures as a replacement for lime or cement in subgrade stabilisation applications and describes the implementation and performance of the selected mixture in the field. In order to decide on the proportions of EAF SS, BFS and Class C FA to be used in the field, tests were performed to obtain the Proctor compaction curves and the Atterberg limits (AL) of mixtures of soil-7% EAF SS-3% BFS and soil-7% EAF SS-3% Class C FA; in addition, the one dimensional swelling behaviour of samples prepared with these mixtures was monitored for over two months. The strength of the stabilised mixtures was determined through unconfined compressive (UC) strength tests. Based on the laboratory test results, the soil-7% EAF SS-3% Class C FA mixture was selected and implemented as a subgrade material in a pavement project in Indiana. Field subgrade compaction quality control was done by performing Dynamic Cone Penetration Tests (DCPT) and Nuclear Gauge (NG) density tests. No cracks or signs of distress were observed on the surface of the subgrade before and after placement of the base course and concrete.

Assessing compaction of existing railway subgrades using dynamic cone penetration testing

Dynamic cone penetration testing has been extensively used in the past for subgrade performance assessment and quality control in road construction practice. However, the method is not commonly employed on high-speed railways. This is due to lack of field data that prove its feasibility as an alternative method for assessing subgrade quality. To mitigate this gap, a series of in situ tests was performed on existing subgrades built with coarse-grained soils at five different sections along the Tehran–Isfahan high-speed railway in Iran. At each subgrade section tested, four parameters for compaction quality control – blow count, degree of compaction, subgrade reaction modulus and dynamic deformation modulus – were determined at nine different depths from subgrade surface. On the basis of the results obtained, a correlation model was developed to relate the traditional quality control parameters of compacted subgrade fill materials with the blow counts. Finally, a simple method using the correlation models established was proposed for assessment of subgrade compaction quality. The method proposed proved to be an alternative approach for evaluating the state of subgrade compaction and also for assessing the subgrade performance of existing railway subgrades.

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.

Field Evaluation of Coir Geotextile Reinforced Subgrade for Low Volume Pavements

ABSTRACT This investigative study focuses on the response of full scale coir reinforced low volume roads when subjected to static loading. The test track of 1.736 km consists of a control section and eight reinforced sections including two types of coir geotextiles and subbase with varying thickness. An assessment of the general behavior of coir geotextile-reinforced sections, to static plate load tests, California Bearing Ratio tests, geogauge and dynamic cone penetration tests is done for evaluation. The study summarizes the results of the executed tests on the reinforced test track in comparison to the unreinforced one. The results reveal that the geotextile with higher apparent opening size is not as good as that of the finer mesh geotextile. A maximum of 112% improvement in the elastic modulus of subgrade is achieved by using a woven coir geotextile of 740 g/m2 mass per unit area whereas 70% increment is attained while using an alternate geotextile of 365 g/m2 mass per unit area. The elastic modulus values are determined from the various field tests and the overall damage analysis is carried out using KENPAVE software. From the analysis, it is noted that an appreciable decrease in the aggregate layer thickness is achieved by using coir geotextile as reinforcement. Use of coir geotextiles in pavements as a reinforcement can therefore help in reducing the demand and consumption of fast-depleting natural resources.

Performance Evaluation of a Trunk-A Road in North Central Nigeria

Pavement maintenance and rehabilitation have been neglected in Nigeria for a very long time and has resulted to maintenance backlog. Design agencies in Nigeria still use California Bearing Ratio (CBR), even though the method is outdated. An introduction of Dynamic Cone Penetration Test (DCPT) was pertinent, even though the method is relatively old in some developed countries, it has not gain much prominence in Nigeria. A flexible pavement, constructed from Bida to Mokwa,, Nigeria, was Rehabilitated after 22 years of construction. This was done by placement of stone base course in one section and lateritic base course in the other. The stretch of the road was then overlaid with asphalt surfacing. Before commencement of the rehabilitation, DCPT tests were conducted on the road to evaluate performance of the pavement base and subgrade. Two years after the rehabilitation, an evaluation was carried out at five selected positions (two at crushed stone base and three at lateritic base) to evaluate the performance of the two base courses. The evaluation was carried out by coring the asphalt concrete and DCPT test below the hole created by corer to indirectly estimate the in-situ CBR of the base and subgrade courses. The results from both the stone base and lateritic base sections satisfy the minimum specifications based on standard. The study also showed that pavement failure along the road is not as a result of the materials used in the base course, but as a result of the excessive axle loads experienced by the road.

Performance assessment of pavement structure using dynamics cone penetrometer (DCP)

Assessing the performance of existing pavement structures, is quite challenging. The repeated triaxial load tests on cylindrical specimens are routinely used to measure the resilient capacity of pavement. The resilient modulus (M_R) testing equipment, is not readily available in an in-situ setup as a result of the complexities of the test protocol. This study investigated the performance and causes of distress identified on existing highway along Eastern Nigeria (Enugu - Abakaliki–Ikom Highway Road). Series of dynamic cone penetration (DCP) tests were conducted and the results were analysed by AFCP-LVR software. California Bearing Ratio (CBR) and Resilient modulus tests were performed to investigate the causes of deterioration on this pavement structure. The results confirmed that the investigated pavement structure failed on the surface, as a result of excessive traffic loads from heavy trucks. The test results further revealed that the asphaltic layer is the only failed layer of the pavement structure. The investigate pavements were confirmed to be designed for low-volume traffics, according to CBR and M_R test results. The predicted CBR, and M_R values from AFCP-LVR software analysis, indicated average variations of 2.8%, and 3.6MPa, respectively compared to the laboratory measured values. This study revealed that excessive traffic load is the major cause of distress on the investigated pavement. The pavement analysis suggested that dynamic cone penetrometer is a suitable tool for assessing the resilient performance of substructures in pavement.

Gravel Liquefaction Assessment Using the Dynamic Cone Penetration Test Based on Field Performance from the 1976 Friuli Earthquake

AbstractThe dynamic cone penetration test (DPT) developed in China has been correlated with liquefaction resistance of gravelly soils based on field performance data from the Mw7.9 Wenchuan earthqu...

Experimental investigation of utilizing waste flue gas desulfurized gypsum as backfill materials

Flue gas desulfurized gypsum (FGDG) is a waste material produced in the power stations during the flue gas desulfurization process. In China, a small amount of FGDG is used as cement additives or for gypsum boards, but there still exist a mass of FGDG due to the lack of reusing methods. Also, the waste fly ash (WFA) is another waste material from the power plant. To alleviate the accompanying environmental issues, large-volume utilizations such as in civil engineering applications are usually adopted to consume these materials. However, these materials cannot achieve high strength due to the lack of amorphous content. In this study, combined with WFA, a large volume of waste FGDG was investigated for the utilizations as backfill materials. With using two types of activators, sodium hydroxide and water glass, in small doses, mixtures with various ratios of FGDG and WFA were included to investigate the mechanical, chemical, microscopic, and softening properties at different curing periods. Then the field experiments including the dynamic cone penetration test and the load plate test were conducted to evaluate the bearing capacity, settlement and compaction effect of the compacted mixtures. The experimental results showed that the NaOH activated mixture (FGDG: WFA = 50:50) could acquire acceptable mechanical properties for backfill applications, which can serve as a practical option for the large-volume utilization of FGDG and WFA.

Reconnaissance on Liquefaction-induced Flow Failure Caused by the 2018 Mw 7.5 Sulawesi Earthquake, Palu, Indonesia

The Mw 7.5 Sulawesi Earthquake 2018 was a catastrophic disaster that resulted in large numbers of casualties. This study aimed to investigate the damages of liquefaction-induced-flow failure in three areas in Palu city, i.e. Petobo, Balaroa, and Jono Oge. It was found that this flow failure occurred on a large scale at a very gentle ground inclination, ranging from 1 to 3%. In order to gain an understanding of the soil conditions in these specific locations, Portable Dynamic Cone Penetration Tests were conducted in Petobo. The results showed that the soil layers in the affected area were in a loose state compared to the non-affected areas. Furthermore, some spots of freshwater inundation were recognized in Petobo and Balaroa, even two weeks after the disaster. Based on this evidence, a mechanism of liquefaction-induced-flow failure caused by a confined aquifer is proposed.

Application of Ground Penetrating Radar to Estimate Subgrade Soil Density

Ground penetrating radar (GPR) technology has been widely used in pavement assessment over the last decade. Assessing the subgrade condition and monitoring its temporal variation provide valuable information regarding changes associated with pavement deterioration, allowing for the beneficial prediction of future road maintenance. This paper presents a method to estimate the density and water content of prepared subgrade soils of highly plastic silt using a 2 GHz GPR scan system and a simple exponential model. A bulk density prediction model was developed based on electromagnetic mixing theory to back calculate subgrade soils density. The model developed determines the soil’s dielectric constant, considering dielectric and volumetric properties of the three major components of soil: air, water, and solid particles. A series of laboratory tests was conducted on six (6) soil samples at various density levels to validate the newly developed model. For validation purposes, sand cone and dynamic cone penetration (DCP) tests were performed and compared with the estimated soils strength from GPR data. The results show that the prediction of soils density and stiffness using nondestructive technology helps efficiently forecast not only pavement deterioration, but potential risks to the subsurface pavement structure with all the advances of time saving using air coupled GPR antenna mounted on a moving vehicle.

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.

Correlation between Unconfined Compressive Strength and Penetration Index Obtained from DCP Tests for Cemented Lateritic Soils

This paper presents the relationship between the dynamic cone penetration (DCP) test results and the unconfined compressive strength of lateritic cemented soils. A series of DCP tests and unconfined compressive strength was performed on lateritic cemented soil. The soils sample used in this study was lateritic soil. The test results for the DCP tests are presented in terms of penetration index. It can be observed that the penetration index decreased with increasing curing period and cement content. Moreover, the unconfined compressive strength of cemented soils increased with curing period and cement content. The relationship between unconfined compressive strength and penetration index is presented. A unique relationship for unconfined compressive strength can be obtained.

CONSTRUCTION OF EARTH FILL STRUCTURE FOR SMALL FARM POND BY USING BHUTANESE TRADITIONAL WALL MAKING METHOD

The Kingdom of Bhutan has mountains as high as 7,000 meters height at the east end of the Himalayas and the semitropical region at an altitude of 100 meters in its south area. Because of its precipitous terrain, stable supply of water for irrigation is difficult without efficient water supply system such as reservoirs, pipelines and so on. Based on the results of preliminary field investigations, existing reservoirs in the Kingdom of Bhutan often have structural problems in its body and foundation. To contribute to an increase in agricultural production in the Kingdom of Bhutan through the development of construction techniques for reservoirs, an earth fill structure for a small farm pond was suggested and constructed in 2015. In this construction, the Rammed earth method, which is well known as a Bhutanese traditional wall making method, was applied as a compaction technique of soil. Authors conducted a follow-up of the earth fill structure in September 2017 to confirm the performance of the wall making method as a construction technique for reservoirs. Based on the results of the portable dynamic cone penetration tests, it is supposed that this rammed earth method couldn’t achieve sufficient compaction energy for construction of earth fill structures for reservoirs because observed N values were comparatively small compared with that obtained from embankments constructed by modern compaction techniques. Therefore, in the construction of earth fill structures for farm pond by utilizing the rammed earth method, improvement in the compaction technique should be considered.

Prediction of relative density of carbonate soil by way of a dynamic cone penetration test

Relative density is an important parameter in geotechnical engineering and the dynamic cone penetration test has been widely used for its assessment. The currently established relationships between the dynamic penetration index and relative density might not be suitable for carbonate sediments due to their unique engineering properties. Therefore, 18 dynamic cone penetration model tests were conducted for carbonate coarse-grained soils. Simultaneously, 18 other laboratory model tests for quartz soils with similar gradations were carried out for comparison. The test results indicate that under the same relative density, the dynamic penetration index of carbonate coarse-grained soils is lower than that of quartz soils. In addition, the particle size and gradation of soils exert a greater influence on the dynamic penetration index of carbonate coarse-grained soils. Based on the test results and considering the influence factors mentioned above, two relationships between the dynamic penetration index and relative density are presented for carbonate and quartz soils, and these relationships could be used to evaluate the properties of soil backfills and base materials.

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.

Evaluation of strength distribution at cut slope of decomposed granite with the use of sounding method and geophysical exploration method

Natural slopes and cut slopes frequently collapse due to heavy rain and earthquakes, causing disasters. Countermeasures must be applied to mitigate such disasters. There is an especially high risk of a collapse at the surface layer of slopes, and thus, evaluating the strength distribution in the surface layer in detail is important to mitigating and preventing disasters. As simple investigation methods for these purposes, there are sounding methods and geophysical exploration methods. In the present study, dynamic cone penetration (DCP) is selected as the sounding method, and the surface wave method (SWM) is selected as the geophysical exploration method. The strength parameters are generally assumed based on standard penetration tests (SPTs), but DCP tests are simpler than SPTs and can be applied to narrow spaces. On the other hand, the SWM can be used to investigate wide spaces in a short time. We developed a synthesized approach to the geophysical exploration method and the sounding method. The two results obtained from the SWM and the DCP tests—namely the shear velocity and the DCP blow count, respectively—need to be converted to the standard penetration test blow count in order to be synthesized. An indicator simulation, one of the geostatistical methods, is employed to simulate the random field of N values by synthesizing the two results. The proposed procedure is applied to evaluate the strength of the weak surface layer of a cut slope composed of weathered granite, and its applicability for practical use is verified.

Analysis of dynamic spherical cavity expansion in undrained modified Cam Clay soil

SummaryIn order to capture the influence of the cavity expansion velocity, this paper presents a semianalytical solution for dynamic spherical cavity expansion in modified Cam Clay (MCC) soil. The key problem is solving the six coupled partial differential equations (PDEs) of cavity expansion, in which the dynamic term is considered in the stress equilibrium equation. The similarity transformation technique is used to transform the PDEs into ordinary differential equations (ODEs). Subsequently, the numerical method using the function “ODE45” in MATLAB is selected to solve the ODEs, which allows the stress and excess pore pressure around the expanding spherical cavity wall to be obtained. The proposed semianalytical solution for dynamic spherical cavity expansion was validated by comparting the degenerate solution with the published quasistatic solution for the MCC model. Parametric study was then conducted to capture the influence of the cavity wall velocity on the cavity expansion response. The proposed solution has potential application to geotechnical problems such as dynamic pile driving, the dynamic cone penetration test, and so forth.

Coir Geotextiles for Paved Roads: A Laboratory and Field Study Using Non-Plastic Soil as Subgrade

ABSTRACT In this paper, pavement proposed on soft subgrade (SG) that requires improvement is studied and reported. One of the methods of improvement is reinforcing SG with geotextile. Laboratory studies were conducted on both paved and unpaved sections, whereas field performance studies were conducted only on paved roads. Three types of woven and one type of nonwoven coir geotextiles were used as reinforcement in the laboratory study, out of which one woven geotextile was used in the field. Effects of reinforcements were studied by placing the geotextiles at different positions of the section in the lab model, and cyclic load tests were conducted and resistance to permanent deformation was reported. Field performances were evaluated by the Benkelman beam deflection (BBD) test, the dynamic cone penetration (DCP) test, and the field California bearing ratio (CBR) test. Test results indicate that the reinforced roads have less distress compared to the unreinforced one. Change in characteristic deflection, DCP indices, and about 50% improvement in field CBR values were obtained for the reinforced one.

Geoelectric versus MASW for geotechnical studies

We explore the role of non-invasive multi-electrode electrical resistivity imaging (ERT) and induced polarisation imaging (IPI) as an alternative to multichannel analysis of surface waves (MASW) for geotechnical site characterisation in view of their higher near-surface spatial resolution. By using regression equations, we assess the relative performance of ERT, IPI and MASW in predicting geotechnical test results (standard penetration test (SPT), dynamic cone penetration test (DCPT) and static cone penetration test (SCPT)) in a site investigation on our IIT Roorkee Campus, India. The results indicate that the average root mean square (RMS) errors in predicting SPT based on ERT, IPI and MASW are 16.95%, 21.9% and 28.03%, respectively. Likewise, the average RMS errors in predicting DCPT based on ERT, IPI and MASW are 15.4%, 15.3% and 56.99%, respectively, and the average RMS errors in predicting SCPT based on ERT, IPI and MASW are 20.15%, 18.65% and 36.49%, respectively. In view of higher resolution for near-surface investigations, ERT/IPI seems to score over MASW in geotechnical site investigation studies. So, a leading role for non-invasive and cost-effective ERT/IPI in geotechnical site investigations is envisaged.

The significance of concrete slab flexural strength inference variation based on its compression strength characteristics in apron pavement analysis and design

Rigid pavement of apron in the airport is a complex structure which is designed based on the sense of balance of sub-grade strength, pavement aggregates, applied load characteristics, and climate. Various sub-grade condition and concrete slab flexural strength values results on the pavement design thickness that have a direct impact on the cost construction. In this study, the rigid pavement design of an apron with various sub-grade condition and concrete flexural strength values are presented. As a reference, the Federal Aviation and Administration (FAA) method is used. Dynamic Cone Penetration (DCP) test value is used to estimate California Bearing Ratio (CBR) values to determine the sub-grade reaction modulus (k). The flexural strength of concrete slab analyzed by several empirical models with constant values range of 0.72-0.9. The pavement structure analysis conducted by FAARFIELD. The CBR values from DCP’s test vary between 6-10% which equal to k values between 31.4-46.8 MN/m3. Concrete slab flexural strength of 4.6 MPa results on the concrete slab thickness of 550-510 mm. Based on k value of 46.8 MN/m3 and K400 concrete strength, the calculated flexural strength varies between 4.15-5.17 MPa and the concrete slab thickness is 570-540 cm. The inference variation of flexural strength based on the same value of concrete compression strength characteristics will produce different concrete slab thickness. The concrete slab thickness tends to increase with the smaller values of inference of flexural strength.