Plate Load Tests Research Articles

Numerical Analysis of the Effect of Crude Oil Pollution on Vertical Clay Trenches

ABSTRACT The presence of oil contamination causes changes in mechanical properties of clayey soil trenches with low liquid limits (CL) such as stress-strain behavior, rupture plain position, plastic zone, and strain energy for soil trenches compared with uncontaminated soils. These changes usually lead to a lower factor of safety against failure and expansion of the plastic zone. The effects of crude oil contamination on the soil shear strength were evaluated by direct shear and plate load tests for various clays and sandy soils. In this research, a numerical finite element modeling in ABAQUS software was used to estimate the effect of oil contamination in the range of 0 to 16% (0%–4%–8%–12%–16%) on the stability safety factor of vertical clayey trenches with heights of 3 m, 4 m, 5 m, and 6 m, and the results were compared with results of a limit state analysis. The findings of the limit equilibrium method show that adding 4% of oil contamination to a clayey trench will decrease 62% of its critical depth. Also, the numerical analysis results show that adding oil contamination in the range of 0 to 16% to the clayey soil will increase the maximum displacements of the trenches to five times their clean state.

A proposed correlation between dynamic and static plate load test moduli for gravelly soils

ABSTRACT Egypt is currently developing huge housing projects at the New Capital, Alamein, and other Egyptian cities. These projects often require soil replacement for roads and buildings. Among the causes of problems observed in some housing projects in the last decade are improper type of soil replacement material and inadequate compaction. Pit-run gravelly soils are commonly recommended for soil replacement because they have the advantages of providing high stiffness, low permeability inherited from their fines’ content and wide availability in Egypt. It is common to use sand cone test and/or static plate load test (SPLT) to assess the quality of compaction. The sand cone test is simple, cheap and rapid; however, it is not reliable with gravel sizes usually found in pit-run gravel, which may exceed 38 mm. Although the SPLT is efficient to assess the quality of compaction and the deformation modulus, it is relatively expensive and time-consuming. The dynamic plate load test is a reliable solution to combine the advantages of both the sand cone test and SPLT. This research includes a detailed laboratory characterization of pit-run gravel collected from Suez deserts and a field testing program including static and dynamic plate load tests on pit-run gravelly soil carried out at several sites in the new capital of Egypt to obtain static and dynamic plate load tests moduli. A statistical approach based on percent of exceedance criterion is adopted to obtain a simple correlation between the static and dynamic plate load test deformation moduli.

Innovative Quality Assessment of Pavement Subgrades Using the Glegg Impact Soil Tester

This article presents the case study of our research in the field of innovative methods of pavement subgrade quality control using the CIST (Clegg Impact Soil Tester) device. The CIST device developed by Dr Clegg from the University of Western Australia measures soil compaction indirectly using the CBR value. The value is evaluated based on the deceleration rate of a falling 4.5 kg weight moving in a vertical guide roller. In Europe, for the assessment of the mechanical efficiency (bearing capacity) of cohesive soils in the pavement subgrade, priority is given to indirect assessment methods especially using the laboratory determination of CBR (Californian Bearing Ratio) and directly through the implementation of a static plate load test (SPLT). This article reports the long-term results of our research in the field of verification and validation of an innovative CIST device, which minimizes the time, space, and economic disadvantages of SPLT. This article presents the results of determining the field of applicability of the CIST device for cohesive soils, the correlation dependencies (CD) of the CBR values determined by the CIST device, and, according to STN 72 1016, the CD of the impact dynamic deformation modulus Evd from the CIV (Clegg Impact Value). We consider the most important results of our long-term research to be a recognition of the ability of CIST to assess the quality of cohesive soils up to a compression value of 40 mm, corresponding to a CBR of 2.2% and a modulus of subgrade deformation of 20 MPa. A very strong correlation dependence of CBRClegg [%] on the moisture content of clayey soils in the interval from 5 to 19% was also observed. The presented knowledge led to the creation of relevant documents for the credible implementation of the CIST device in the system approach for assessing the quality of the pavement subgrade.

Comprehensive evaluation of strength parameters of soils by using DCP, DSCP, and LWD devices

ABSTRACT Traditionally evaluation of strength parameters of soil using plate load test is time-consuming, laborious and cumbersome process. This study is focused on evaluating the strength parameters of compacted soils, quickly and cost-effectively in terms of dynamic penetration index (DPI), dynamic resistance (DR), cone index (CI), and dynamic deformation modulus (E LWD ), analyzing their relationship with water content. Results, show strength parameters increases as water content decreases,with significant increase in DR, CI and E LWD for CBR changes from 5% to 10%, followed by marginal increase This study emphasized that the strength parameters vary with the physical properties of soils, for which correlations were proposed between CBR, DR, CI, and E LWD values, resulting in best-fit models. These parameters effectively indicate targeted in-situ strength conditions, aiding in assessing repeatability and uniformity of compaction. The mean DR, DPI, N, and E LWD were reported as 61.74 MPa, 6.41 mm/blow, 8 blows/100 mm, and 54.11 MPa, respectively from the field case study.

SUBSTANTIATION OF THE ROAD CONSTRUCTION UNBOUND MATERIALS CALCULATION MODEL WITH GEOGRIDS STABILIZATION

Summary. Based on the results of experimental studies conducted on different types of flexible pavement structures, the authors of the article examined the behavior of unbound material reinforced with geogrid. A series of static plate load tests were carried out, and the deformation modulus values of traditional and reinforced pavement structures were determined. The impact of the geogrid, installed at the base of the unbound layer of the pavement structure, on its deformation modulus was investigated. It was found that the use of geogrids significantly increases the equivalent deformation modulus of the pavement, depending on the thickness of the inert material layer and the deformation characteristics of the subgrade soil. The effectiveness of the reinforcement depends on the ratio of the deformation characteristics of the pavement and the subgrade soil, as well as the relative depth of the geogrid installation. The greatest effect is achieved on weak soils under large deformations. The results obtained are significant for further research and practical application of pavement reinforcement technology using geosynthetic materials. Keywords: highway, pavement structure, biaxially oriented geogrid, geosynthetic reinforcement, plate load tests, deformation characteristics, loading, reinforcement coefficient, field experiment

Laboratory Evaluation of Marginal and Industrial Waste Material in Geocell-Reinforced Pavements under Cyclic Loading

Abstract The availability of quality materials for the construction of pavements has been a problem in some regions. This scarcity enforced geosynthetic materials as one of the quests for su1stainability in the pavement industry. This study attempted to stabilize marginal (tunnel muck, reclaimed asphalt pavement material) and industrial waste (zinc slag) materials by employing high density polyethylene geocell to appraise the effectiveness of geosynthetic reinforcement in enhancing the characteristics of pavement materials and mitigating their rutting. The cyclic plate load tests are performed on marginal and industrial waste material with geocell-reinforced and unreinforced base layers over black cotton soil as the subgrade. The tests were conducted following the trapezoidal loading pattern with a 0.77-Hz frequency. The geocell-reinforced pavement performance was evaluated for resilient deformation, accumulated permanent deformation, rut depth reduction, traffic benefit ratio, and base layer thickness reduction. The mechanistic empirical pavement design guide (MEPDG) permanent deformation performance (PDP) model framework was used to predict the accumulated permanent deformation in unbound granular layers and to differentiate the rutting performance in geocell-reinforced and unreinforced sections. This study determined the material constants of the MEPDG PDP model for marginal and industrial waste materials used in the pavement section for quantifying the reduction in base layer thickness.

The effect of the geometrical properties of geocell reinforcements between a two-layered road structure under overload conditions

Depending on the project traffic, the total thickness of a granular base can reach excessive values. Granular layers of large thicknesses undoubtedly extend the duration of a project and cause high project total costs. In this study, the improvement in settlement behaviour of unbound granular base layers reinforced with geocell was investigated by way of large-scale laboratory tests and finite element modeling. Plate loading tests were performed on unreinforced and geocell reinforced base layers, which were constructed on subgrade soil with a low bearing capacity under 1750 kPa overload condition. It was determined that the amount of settlement observed at the same stress levels decreased with an increase in the aperture size from 440 mm to 660 mm and the geocell height from 100 mm to 150 mm. The reduction in settlement potential, which reached 78% compared to the unreinforced reference section around 25 kPa, decreased to 55% at around a 200 kPa standard load. With an increase in the vertical stress level, the effectiveness of geocell reinforcement decreases and a serious decrease occurs after 500 kPa, becoming completely unserviceable when a level of 1000 kPa is to be exceeded. Although the difference between the experimental results and the modeling values remained below 5% in the reference section, it reached as high as 30% differences in the geocell implemented sections up to 200 kPa, due to three-dimensional geocell adaptation problems within the finite element calculations. In this way, it will be possible to increase the performance of road surfaces by keeping the pavement thickness constant, and also it will be possible to design more economical sections by reducing the required thickness.

Utilization of recycled construction and demolition waste to improve the bearing capacity of loose sand: an integrated experimental and numerical study

ABSTRACT The present study examines the efficacy of the thickness of recycled construction and demolition waste (RCDW) layer (0.4D, 0.6D, 0.8D, 1D and 1.2D; D: diameter of footing) prepared at different relative densities (30%, 50% and 70%) overlaying on loose sand. Two sizes of RCDW, 5 mm named RCDW-I and 10.6 mm named RCDW-II, were used in this investigation. The plate load test and finite element analysis using ABAQUS were carried out on different combinations. Moreover, a large box direct shear test was conducted to determine the angle of internal friction (α) of RCDW-I and RCDW-II at relative densities (ID) of 30%, 50% and 70%. With the usage of RCDW layer over sand, the ultimate bearing capacity increases by 640% for RCDW-I and 597% for RCDW-II, and the corresponding decrement in the settlement was 36.86% and 33.54% (at ID = 70% and u = 1.2B), respectively. The conjoined analysis shows that RCDW-II performs better than RCDW-I at lower ID. Whereas the opposite trend is witnessed at higher ID. The experimental results were compared to the numerical model created in ABAQUS 3D. In addition, regression analysis was performed using SPSS software to build empirical expressions of the given results.

An Evaluation of Treatment Effectiveness for Reclaimed Coral Sand Foundation in the South China Sea

Mega land reclamation projects have been carried out on the coral reefs in the South China Sea. Coral sand was used as a backfill material through hydraulic filling, with fill heights ranging from 6 to 10 m. To enhance foundation stability, vibro-flotation and impact rolling have been employed. However, the uneven distribution of coral sand, irregular particle shape, lower single-particle strength, and paucity of engineering cases for reference have posed challenges in evaluating the effectiveness of these foundation treatments. In this study, the effectiveness of vibro-flotation and impact rolling on the densification and bearing capacity of coral sand foundations has been investigated. In situ tests, including the plate load test, California Bearing Ratio (CBR) test, density measurements, dynamic penetration test (DPT), and settlement monitoring, were conducted at four distinct zones: an untreated zone, a vibro-flotation zone at a 5 m depth, a vibro-flotation zone at a 10 m depth, and an impact rolling zone. The findings suggest that coral sand exhibits promising characteristics for foundation construction. Seepage and self-weight consolidation following land reclamation formation significantly enhance the compaction degree of the coral sand foundation, thereby meeting the requirements for areas with lower bearing capacity demands. Both vibro-flotation and impact rolling techniques could significantly enhance the foundation-bearing capacity, with marginal differences between them. Since the machinery is simple and construction speed is quick, the impact rolling method is considered to be the most efficient for the treatment of coral sand foundation. The DPT results suggest that the reinforcement effect of both vibro-flotation and impact rolling on the deep foundation is not as substantial as the surface layers. This study provides valuable insights into optimizing foundation treatments for land reclamation projects on the coral reefs.

Bearing capacity of lunar soil ground under extraterrestrial environmental effects

Lunar environment features a low gravity field and ultra-high vacuum which shows significant effects on the bearing behavior of lunar soil ground for future lunar habitation. Therefore, the 2D Discrete Element Method was employed to simulate the plate load tests under different gravity fields in non-vacuum (i.e., excluding the van der Waals force) and high-vacuum (i.e., including the van der Waals force) environments, analyzing the bearing behavior and soil response under extraterrestrial environmental effects. The results show that a bilinear line bounded by 1g can be employed to describe the gravity effect on the gravity factors for ultimate bearing capacity and coefficient of subgrade reaction. The slopes are different in low and high-gravity fields, indicating that the high-gravity effect in a centrifuge cannot be directly applied to predict the bearing behavior of lunar soil ground in a low-gravity field. The affected area becomes deeper in depth and narrower in width with the decreasing gravity level in non-vacuum environment, while the affected area becomes deeper in depth and wider in width with the decreasing gravity level in high-vacuum environment. Such observations can provide advice for developing analytical models for the bearing capacity of lunar soil ground considering the extraterrestrial environmental effects.

Experimental study of the behavior of square footing on reinforced sand with treated geotextile

Bearing capacity of reinforced footing clearly depends on the characteristics of interface between geosynthetic and soil. A suitable solution for increasing the bearing capacity is to treat the geotextile surface by various additives. This study reported the results of plate load test on square model footing resting on reinforced sand with and without treated geotextiles to survey the effects of the treatment of geotextile on settlement and bearing capacity. The treated geotextiles were made using additives onto the surface, with a layer of sand located on the top. Geotextile sides were treated in the same way. Different additives including the lime, cement, emulsion, and the effect of the number of layers were considered. The bearing capacity ratio values (BCR), improvement ratio values (IR) and variation of load-settlement ratio obtained from the treated models were presented. The results showed that the treatment of geotextile has a great effect on the behavior of reinforced sand and thus bearing capacity. Also, the test results indicated that lime-treated geotextiles provided better improvement than other additives. The maximum improvement in the bearing capacity of square footing supported on treated geotextiles was found to be 75% compared with the pristine geotextiles.

Utilizing a new columnar inclusion approach to treat loose and granular soils

This study introduces an innovative method to improve the load-bearing properties of loose fine-grained soils, mitigate geodynamic stress-related risks to supported structures, and address the issue of end-of-life tire waste. This technique involves blending shredded end-of-life tires with sandy soil and compacting the mixture into sand-rubber compacted piles (SRCP), thereby enhancing both the soil's load-bearing capacity and its ability to absorb energy. As per the ASTM classification system, the sand used in this study falls into the category of fine to medium poorly graded sand, with particle sizes ranging from 4.75 mm and an average particle size (D50) of 0.2 mm. An experimental program was devised to investigate the physical and mechanical properties of this composite material. Field plate load tests (FPLT) were conducted to assess the effectiveness of the proposed technique, taking into account factors such as the initial relative density of the soil, the ratio of rubber to sand (R/S) in the mixture, and the distribution of piles in the surrounding environment. The results from the plate load tests revealed that when SRCP was applied to soil with a relative density of 40 %, the ultimate load-bearing capacity increased by 100 %.

A Study on the Analysis of the Ground Compaction Effect According to the Roller Operation Method through CMV Analysis Using IC Rollers

In road construction, the compaction process using vibratory rollers is essential to increase the ground stiffness in earthworks. There need to be clear standards regarding the operation of compaction rollers during compaction work. Various simple quality inspection techniques have been developed to check the stiffness of the ground, but plate load test and field density test are the most commonly used test methods to evaluate the degree of compaction during road construction. However, both inspection methods could be more efficient, as they cannot be performed in all sections due to time and cost. Additionally, in compaction work today, the worker will individually judge the number of compactions, thickness, speed, vibration etc. based on his or her own experience. This means that the quality of compaction varies depending on the worker. In this study, quality inspection results for all sections were obtained using an intelligent quality control system that employs an IC roller, a technology that is now commercially available. The effect of the operating conditions of the vibrating roller (roller compaction direction, compaction roller speed, and compaction roller vibration method) on the compaction quality was analyzed using the intelligent quality control value. Through our highway construction site tests, it was found that the speed of the compaction roller and the vibration method of the compaction roller affected the degree of compaction, but the direction of compaction did not. Therefore, if the compaction work is performed by adjusting the driving speed and vibration method of the vibrating roller according to the ground conditions, repetitive compaction work can be reduced, thereby reducing construction costs and lowering work time, which will achieve an improved work efficiency.

Application of Clay–rubber Mixtures for the Transportation Geotechnics—the Numerical Analysis

Abstract The use of waste materials (including rubber) in industry is one of the most important issues in terms of environmental protection. One of such applications is the use of soil–rubber mixtures in backfills or lower layers of embankments or road structures. The numerical analyses of the behavior of a clay–rubber mixture layer built into a road embankment are presented in this article. An elastic-perfectly plastic model with a Coulomb–Mohr yield surface was used in the finite element analysis. The parameters of soil–rubber mixtures adopted for the analysis were estimated on the basis of triaxial tests: monotonic (UU—unconsolidated undrained, and CU—consolidated undrained) and cyclic (CU) performed with low frequency (f = 0,001 Hz). The triaxial tests were carried out on mixtures of kaolin (K) and red clay (RC) with the addition of 1–5 mm rubber granulate (G) in the amount of 5–25% by weight. Numerical analyses included a static plate load test (VSS) of a layer made of a rubber–soil mixture built into the embankment and testing the stability of embankments using the c–ϕ strength reduction procedure. The results of laboratory tests confirm the necessity of testing soil–rubber mixtures each time before their use in embankments. The observed overall decrease in shear strength and stiffness of the tested material is variable and depends on the type of soil and the content of rubber waste. Satisfactory results of the analysis were obtained, both in terms of the values of layer stiffness modules and slope safety factors, which allows for the conclusion of the possibility of using soil–rubber mixtures (with the recommended granulate addition up to 30% by weight) in the layers of road embankments and (depending on the road class) in the lower layers of the pavement structure.

Determining the Stabilised Subfoudation Soil Deformation Modulus According to the Plate Load Tests and Geotechnical Monitoring Data

Introduction. The subsiding soils, which are widely spread in the south of Russia, create a number of problems and hazards due to the high probability of subfoundations subsidence in case of exceeding the values of initial soil moisture and initial pressure for subsidence. This is an important phenomenon to be considered at all life cycle stages of a building or structure, especially at the stage of design, when the scientifically justified design and technological solutions must be developed to ensure the reliable operation of facilities in the complicated engineering and geological conditions being studied hereby. The present article analyses the acting federal and regional regulatory and technical documentation in the field of buildings and structures design on the subsiding soils. Based on the numerical experiment, the incorrectness of the results sometimes received upon following the normative methodology is shown. A new calculating methodology based on determining the stabilised subfoudation soil deformation modulus according to the plate load tests and geotechnical monitoring data is proposed.Materials and Methods. The research comprised:– analysis of the existing approaches and methodologies for the subfoundations and foundations design on the subsiding soils;– numerical experiments, including calculations according to the normative methodology, which implied variation of the original data of both the initial properties of soils and technological parameters of stabilisation, as well as statistical processing of the results;– analysis of the carried out earlier by the authors geotechnical monitoring results of the buildings built on the stabilized soils and experimental study of the deformation properties using a patented device;– determining the main factors having influence on the design solutions for the subfoudation soils and building foundations strengthening under a complicated set of operational loads and establishing a new dependence of the stabilised soil deformation modulus on the initial soil deformation modulus and percentage of soil reinforcement.Research results. It has been established that the existing methodologies for calculating the stabilised subfoudation soils are not enough precise for determining the forecastable subsidence of buildings and structures, and the obtained design values do not always correspond to the factual deformations of subfoundations and foundations. The dependence of the stabilised subfoudation soil deformation modulus on the initial soil deformation modulus and percentage of soil reinforcement with the cement-sand mortar has been traced. A new calculating methodology has been developed based on determining the stabilised subgrade soil deformation modulus according to the data of the plate load tests using a patented device and geotechnical monitoring.Discussion and conclusion. It has been established that the deformation modulus of the soil mass stabilised by the cementation method depends non-linearly on percentage of soil reinforcement with the cement-sand mortar and the initial soil deformation modulus, and this dependence is described by a second-order surface equation of a general form. It is recommended to apply the discovered dependencies for designing the technological parameters of the subsiding soils stabilisation in the Rostov region conditions.

Common Mistakes in Execution of Plane Load Test

Shallow foundation is the preferred foundation whenever possible, as it is economically more feasible compared to deep foundation. The design method for shallow foundation has long been established by Terzaghi. The Terzaghi’s bearing capacity equation requires soil strength parameters for its calculation. To obtain accurate results, undisturbed sample for laboratory testing is necessary. However, depending on the accuracy of soil sampling and laboratory testing, the results can have large inaccuracy. The in-situ determination of shallow foundation can be carried out by plate loading test. It is a well-established test which was standardized by British Standards in 1990 and American Society for Testing and Materials in 1994. The testing method is simple, and the standards provide flexibility in the execution of the test. Unfortunately, this flexibility can cause mistakes in the execution of the test, as practitioners can be selective in choosing the test procedure to minimize the test duration and/or cost. These mistakes can cause the plate load test results to be unusable or lead to erroneous results. This paper aims to address common mistakes in execution of plate load test.

Evaluation of roller compacted concrete for its application as high traffic resisting pavements with fatigue analysis

Roller compacted concrete is a special kind of concrete developed for dams and low-volume traffic pavements, such as yards, lots, storage areas, etc., with the aim of easy compaction under rolling loads without requiring formworks. Roller compacted concrete is primarily used for low-volume traffic pavements as it has limited cement content which reduces cohesion, affecting its fatigue, abrasion and shrinkage resistance. Testing RCC is also quite difficult as beams and molds have to be extracted from slab specimens, thereby limiting the studies aimed at fatigue analysis which require many samples. This study aims to develop a heavy-loaded high-volume traffic-resisting Roller compacted concrete by altering the mix design of pavement quality concrete evaluating its mechanical properties, abrasion, and shrinkage strains alongside analyzing the microstructure. Also, the fatigue life of Roller compacted concrete has been compared with pavement quality concrete using normal distribution and different Weibull distribution methods and analyzed using a plate load test. The results showed that mix RCC7 (Cement: Fine aggregate: Coarse aggregate: Water = 406.8: 892.8: 863.6: 127.5 kg/m3) achieved a compressive strength, split tensile strength, flexural strength, and percent abrasion loss of 43.86 MPa, 4.67 MPa, 4.92 MPa, and 11.7%, respectively at 28 days. Also, shrinkage strains were nearly 31% lesser than pavement quality concrete. Fatigue results and stress variation profile from plate load test prove that Roller compacted concrete having 13% cement also has better stress absorption capability even if it lacks good stress distribution and can be used as a pavement slab for medium-heavy loaded high-volume traffic- resisting pavements such as state highways.

Quality control of fine-grained embankments using penetration tests

The compaction control of earth works is an essential task in geotechnical engineering. In order to build more sustainably and to reduce project costs, fine-grained materials are more often used for embankment construction nowadays. The quality control of compacted soil layers is usually defined in terms of deformation moduli obtained from static and dynamic plate load tests or based on the degree of compaction, which is generally related to the Proctor density. Penetration tests, such as cone penetration tests (CPT), seismic flat dilatometer tests (SDMT) or dynamic probings (medium heavy dynamic probings (DPM)), show a potential for assessing the compaction along vertical profiles but no standardized quality criteria have been elaborated yet. The present work investigates the effects of different water contents and degrees of soil stabilization on results of CPT, SDMT, DPM, plate load tests and Proctor tests for an 8 m high trial embankment, characterized by a clayey to silty material. CPT and DMT results were found to strongly correlate with deformation moduli of static and dynamic plate load tests, enabling the definition of new quality criteria for compaction control.

Estimation of internal friction angle for working platform materials by plate load test

This paper reviews the load–settlement behaviour of 499 plate load tests of various diameters undertaken on granular soils and working platform materials to determine the angle of internal friction mobilised by the test. The observed settlement of individual plate load tests at relatively small settlement has been extrapolated to a theoretical failure of the plate at 10% and 15% of the plate's diameter (D). For each test an effective angle of internal shearing resistance was calculated based on the bearing resistance associated with the stress required to cause settlement of 0.10 or 0.15 times the plate diameter. The results are presented along with a discussion on the use of high-friction materials in working platforms and shallow foundations. Characteristic values for the effective angle of internal shearing resistance are provided for all working platform materials tested, as well as tests undertaken on platform materials comprising crushed brick and concrete. These values are compared to shear box test results on similar materials. Characteristic values of ϕ′ varying from 44° to 46.4° (0.1D) and 45.3° to 47.8° (0.15D) for crushed brick and concrete materials are calculated, which are slightly higher than those determined from tests on Type 1 material.

Evaluation of Granular Fill Layer Underlain by Soft Clay Soil Using Large Scale Cyclic Plate Loading Tests

Evaluation of Granular Fill Layer Underlain by Soft Clay Soil Using Large Scale Cyclic Plate Loading Tests