Plate Load Tests Research Articles

The effect of soft clay improvement using Prefabricated Vertical Drain (PVD) for rigid pavement structure

Rigid pavement is widely used in subgrade conditions that have low bearing capacity so that it will affect the life of the road plan and rigid pavement performance. Soil improvement that can be done is by using Prefabricated Vertical Drain (PVD). Soil consolidation with plate load test is carried out to get the modulus of subgrade reaction. Modulus of subgrade reaction without PVD is 2179,24 kN/m2/m and with PVD distance of 100 mm is 11311,09 kN/m2/m. The modulus of the verified subgrade reaction without PVD is 22419,21 kN/m2/m and with PVD is 38718,40 kN/m2/m. The thickness of the analyzed plates are respectively of 150 mm, 200 mm, 250 mm, 300 mm, and 350 mm. The position of the vehicle wheel load is in the middle, the end, and the edge. The deflections due to the position at the middle, the end, and the edge loads respectively for the entire plate thickness are reduced by an average value of 31%, 34%, and 33%. Rigid pavement performance based on the modulus of subgrade reaction and deflection caused by MST 10 ton vehicle loads with a 1.2 axis configuration shows that soil improvement using PVD can increase the modulus of subgrade reaction and reduce deflection values.

Evaluation of airfield concrete block pavements based on 3-D modelling and plate loading test

Concrete pavements are commonly used in some areas of airfields such as aprons. Repairing these pavements is costly and time-consuming, and it also disrupts flight operations. The use of concrete block pavement is a more suitable option at aprons. Fewer studies have been done on this type of pavement in the airfields than on roads. For further studies, the performance of this pavement was examined by making a 3D model and a test track with dimensions of 2 m × 2 m. This sample was composed of subgrade, subbase, base and Cement-Treated Base (CTB) layers, with 15 cm thickness, for each layer, bedding sand with 3 cm thickness and a Unipave-shape (zig-zag) concrete block pavers with 8 cm thickness and herringbone pattern. Then their quality was controlled, based on Federal Aviation Administration (FAA) regulation. At the next step, Plate Load Test (PLT), was conducted on this sample. For this purpose, a setup including a concrete foundation and a reaction beam was built. For the first time in related research, several 3D models of concrete block with all its angles and corners representing their actual dimensions were made using ABAQUS software. The field studies' experiments result on the materials were used to define the characteristics of the model components, and then the force–deflection curve, as a guidance chart was presented. Studies have shown differences in opinion about the amount of elastic modulus of block and jointing sand. The 3D model analysis result showed that the elastic modulus of the concrete block surface could be taken into account at 2000 MPa to achieve the most coordination between finite element analysis and PLT results. Then, the curve of the allowable number of repetitive loads (N) vs. wheel load pressure was illustrated by selecting the horizontal strain and stress at the bottom of CTB as the failure criterion. Moreover, analysis of the allowable number of load repetitions through Miner’s theory indicated that the equations that calculate N, based on the horizontal stress, achieve more consistent results relative to corresponding equations calculated based on the horizontal strain. According to finite element analysis results, by increasing load pressure, the interlocking of Airfield Concrete Block Pavement (ACBP) improved and the rate of decreasing of the allowable number of load repetitions declined.

Bearing capacity-relative density behavior of circular footings resting on geocell-reinforced sand

Geocell reinforcement (GR) improves load-deformation behavior of shallow foundations. A series of instrumented large-scale plate load tests was performed to ascertain such improvements and to correlate that to the relative density (Dr ) of geocell-reinforced sand (GRS). Variable effects on stiffness, bearing capacity (BC), load dispersion and strain-stress behaviors are discussed. The extensive tests made it possible to arrive at a simplified analytical procedure for predicting the BC of circular footings on GRS, taking into account probable shear failure mechanisms and monitored GR deformation. These results allowed the validation and generalization of the procedure reduced from an equivalent-layer BC model considering ‘confinement’ and ‘stress dispersion’ effects on the failure mechanism. Load dispersion angle and strains increase with increasing the sand Dr resulted in significant stress reduction below the GR. This was found most beneficial for the higher densities ranges. The proposed analytical approach can confidently be used for practical design purposes.

Deformation modulus tested by the falling ball test method and the experimental verification

In filling engineering, the mechanical properties of geomaterials are the most important mechanical indicators. With the improvement of the measurement technology, the falling ball test (FBT) method has been gradually popularized and applied to the testing of geomaterials mechanical properties. In order to verify the testing accuracy of the FBT method, experimental results of the deformation modulus tested for the homogeneous fine-grained materials and the layered structures using the FBT method are compared with the K 30 plate load test, which is the earliest and the most widely used in-situ test method. And some conclusions are drawn in this present paper.

Plate load tests for investigation of the load–settlement behaviour of shallow foundation on bitumen-coated geogrid reinforced soil bed

The paucity of the desirable construction land in India due to day by day increasing population has put grand challenges in front of engineers. So they accentuated the use of undesirable construction land which is having low bearing capacity and large plastic deformation. Among several ground improvement techniques, geosynthetic reinforced soil system is widely adopted as foundation medium keeping in view its economical benefits and sustainable development. Therefore, the main objective of this study was to investigate the effect of a bitumen-coated geogrid reinforcement on the bearing capacity ratio of a shallow foundation in a two-layer silty clay foundation bed. The top layer of locally available silty clay was compacted at OMC (19%) with 0.95MDD, and the bottom soft layer was compacted at dry side of OMC (15%) with 0.75MDD. Various model plate load tests were carried out using a square footing of size 200 mm and thickness 25 mm over a silty clay bed reinforced with bitumen-coated geogrid BX-40, BX-60 and BX-80 having different ultimate strengths in a test tank of dimensions 1000 × 1000 × 1000 mm. The effect on bearing capacity and plastic deformation due to varying end conditions of geogrid reinforcement was also investigated. The other various parameters investigated were the top spacing ratio, width of the geogrid, no. of layers of the geogrid and the stress distribution in various reinforcement layouts. The bearing capacity ratio of reinforced clay was found to be increased by 20–55% than unreinforced clay. The settlement reduction factor of reinforced clay was increased by 9–40% than unreinforced clay. Also the vertical stresses were reduced up to 20% in reinforced clay.

Laboratory and Numerical Studies on the Performance of Geocell Reinforced Base Layer Overlying Soft Subgrade

The use of geocells for support of foundations on weak subgrades has been gaining popularity in recent years. Detailed studies were performed in this work through laboratory tests and numerical simulations to investigate the influence of different parameters on the geocell supported foundations on soft subgrades. A series of large-scale laboratory plate load tests were performed on the geocell-reinforced base layer overlying soft subgrade. The soft foundation soil was simulated using blocks of Expanded Polystyrene (EPS) in the laboratory tests for obtaining consistent subgrade conditions between the tests. The numerical analyses were performed in three-dimensional finite difference numerical program Fast Lagrangian Analysis of Continua in Three Dimensions (FLAC3D). The numerical models were calibrated against the data obtained from laboratory tests. This paper deals with investigating the influence of different parameters such as pocket opening size, height and size of the footing on the performance of geocell-reinforced base layer overlying soft subgrade. The provision of three-dimensional cellular reinforcement (geocells) in the base layer has substantially increased the bearing capacity of the pavement section and the optimum aspect ratio of geocell pocket was found to be close to unity. From the parametric study, it is observed that the potential benefits of geocell reinforcement increases with reduction in weld spacing and height of geocell while the influence decreases with increasing loading area for constant height of geocell layer.

Plate load test on rock with soaking under a massive raft foundation

The Iconic Tower, a 385.8 m high-rise building, is the landmark of Egypt New Capital’s Central Business District project and will be the tallest building in Africa when completed. The location of the Iconic Tower is underlain by basalt rock and supported by raft foundation. Obtaining the accurate performance parameter experimentally is key to foundation design. Due to high elastic modulus of the rock, settlement of the bedrock under design load is estimated around 2 mm, which is sensitive to any millimeter-scale errors that may cause deviation to the result. The high flatness and stiffness of loading plate and the underlying grout bedding is key to minimize the error. The results show that the behavior of bedrock under the range of test stresses can be closely presented by a bilinear elastic stress deformation. Excavation-induced disturbance leaves open joints and fractures in the bedrock which produce plastic settlement in the bedrock under loading in addition to the settlement caused by soaking the bedrock under the design load for 24 h. The present study was able to overcome various challenges in the testing procedure, to provide a methodology to obtain the deformation characteristics of basalt bedrock with argillaceous interlayers under dry and wet conditions, to validate the suitability of the test setup and to obtain reliable results. The study also enabled elaborate design and cost savings.

Evaluation of Reclaimed Hydrated Fly Ash as an Aggregate for Sustainable Roadway Base Material

This paper summarizes the findings from laboratory and field performance testing of reclaimed hydrated class C fly ash (HFA) stabilized with a triangular aperture geogrid. This phase of testing was performed on HFA laboratory specimens and field test sections. The laboratory test results provided estimates for design input values, while the field testing assessed performance characteristics including the as-constructed modulus of the subgrade reaction, the in situ resilient modulus, and permanent deformation. For the laboratory portion, all results were derived from tests conducted on specimens immediately after sample preparation and after a 7-day cure. The compressive strength of reclaimed hydrated class C fly ash increases with curing. The strength of the HFA material can be further increased when mixed with a chemical stabilizer. For this project, chemical stabilization with lime was not viable because the lime supplier was too far from both HFA source and project site. Based on cyclic plate load tests, the in situ resilient modulus of the HFA and geogrid-stabilized HFA layers were determined on site. This paper reports the findings from the laboratory and field plate load test and highlights the potential use of geogrids in the stabilization of HFA.

Deformation modulus of rock foundation in Deriner Arch Dam

Civil engineering structures such as gravity concrete dams, arch dams, pressure tunnels, foundations of high-rise buildings and bridges are generally founded on rock. Design and performance of these structures are highly dependent on the deformation modulus of the rock mass so that expected deformations and/or differential settlements stay within the tolerable limits of the structures. In situ deformation modulus measurements of rock masses are generally performed by using the borehole dilatometer and plate loading tests in Turkey. The diameter of plate loading test device is 30-35 cm. Tests are performed in small unlined tunnels excavated in different elevations of dam abutments. The deformations upon loading are measured on the loading plate in the plate loading tests. It is not possible to exclude the effect of excavation disturbed zone since deformations are not measured with these devices. Large diameter plate test system may have multiple level extensometers set in drill holes opened perpendicular to loading plates. Reading from these extensometers may be utilized to exclude the effect of disturbed zone close to surface together with stress distribution estimated by using elastic theory. There are several field test methods for determining deformation modulus and each method has its own shortcomings. The optimum methodology to correlate plate loading test results with corresponding in-situ deformation modulus values is to back-calculate deformation modulus by using settlements measurements during the construction of dam body. In this paper, Deriner Arch Dam settlements measured during the construction are used to back calculate deformation modulus. It is found that in situ deformation modulus is about two times higher than the average value determined by plate loading tests. This finding will have important effects on the depth of foundation excavations, concrete layers to fortify structure foundations and the amount of consolidation grouting

Numerical modelling of geocell reinforced slope by use of plastic bottle waste

Nowadays, waste management should be one of the focuses in controlling a healthy and sustainable environment. It is undeniable that plastic bottle waste has covered the earth’s surface. One of the solutions to reduce the polluting impact is to use it as a geocell in the geotechnical field. The previous researchers more study about slope reinforcement using fabricated geocell. In this study, geocell is made by utilizing plastic bottle waste. Slope stabilization using geocell is a kind of internal stabilization. Other kinds of slope stabilization, such as using sheet piles and gravity walls, are external stabilization. The purpose of this study is to obtain an overview of the effect of the geocell reinforced slope. From experimental studies using plate load test, results obtained that geocell reinforce soil can increase the bearing capacity of the soil. Numerical modelling uses PLAXIS 2D modelled geocell reinforce slope as a slab that can spread the load widely over the reinforced area, also known as beam model. Young’s modulus of geocell-soil composite is obtained from experimental studies, empirical equation and validated using axisymmetry in PLAXIS 2D. The results of this study, generally geocell reinforce slope can restrain the slope from failure deformation by redistributing the loads in a large area. The significant effect is shown in sandy soil with a high improvement factor (IF), different to the reinforcement in clayey soil with a low improvement factor (IF). It implies that plastic bottle waste can be used as a geocell which can increase its economic value. Since it is applicable, it can reduce the pollution caused by plastic bottle waste.

Application of the Dynamic Cone Penetrometer (DCP) Test for Determination of the Geotechnical Characteristics of Marl Soils Treated by Lime

Quantitative estimation of mechanical characteristics of soils and determination of their behavior using in-situ experiments have always been one of the main concerns of geotechnical engineers. So far, various methods have been introduced to achieve this goal, among which the Dynamic Cone Penetrometer (DCP) test has become more popular as one of the most accurate and efficient methods. Therefore, in this study, an attempt was made to examine the correlation between different soil parameters by performing DCP test along with a series of conventional tests including Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) tests on marl soil samples containing 2, 5, 8% lime at 1, 7 and 15 curing times. Furthermore, since the modulus of subgrade reaction (Ks) is needed in the design of pavements and their underlying materials, Plate Load Test (PLT) was performed to determine Ks. The results showed that the addition of lime up to 5% increased UCS, CBR and Ks and decreased dynamic penetrometer index (DPI) of marl soil samples. Further addition of lime had a negative effect on the mechanical characteristics of the samples. Moreover, using the equations obtained from the correlations in this study, strength characteristics and modulus of subgrade reaction of the stabilized marl soil can be estimated by knowing the DPI of the samples. The results of this study showed that the use of the DCP test as a cheap and easy-to-use method can provide a comprehensive view of soil behavior in civil engineering projects with an acceptable coefficient of determination to geotechnical engineers.

Evaluating of geosynthetics reinforced road base with plate loading tests

Evaluating of geosynthetics reinforced road base with plate loading tests

Revision of the Spanish quality control procedure for rockfills and random fillings

Infrastructure quality control must be done through an adequate control process, which must be well planned, programmed and executed. It implies the revision of the specific control procedures as part of the general objective of continuous improvement. It must be applied to the construction of quarries with stone materials, called rockfills for large sizes or random fillings for intermediate products. There continues to be a problem in terms of compacting control methods in the execution of these diggings, with little practical development of new techniques when the spread is of good – quality material an aspect that must be revised in order to ensure the quality of the final result extended and compacted. The current procedures for Quality Control in rock compaction have limited operability. For example, the granulometric analysis with macro-pits (4m3) it is have done with heavy fractions, being a destructive testing. The average density control by nuclear methods has high heterogeneity, low performance and low thickness tested. The topographic measurement settlement is the most accurate, but it is a poorly referenced method. For the wheel impression test, the required values do not impose any limitation.This research studies the application use to granites, slates and granitic alteration soils stabilized using cement. The necessary field and laboratory works were developed in order to elaborate new test procedures for a proposed compaction control in rocks. The compaction control procedures revised were wheel impression test, topographic settlement and plate load test (PLT). Doing simple regression on SPSS, in which any predictor outcome variable (dependent) should be placed (independent). An analysis of variance ANOVA shows the sums of squares and the degrees of freedom associated with each: is significant at p < 0,05. There is less than 0,5% chance that an F Levene – ratio this large would happen if the null hypothesis were true.

Bearing Capacity Standards for Forest Roads Constructed Using Various Technologies from Mechanically and Chemically Stabilised Aggregate

Forest roads are essential for adequate forest management and environmental protection. They enable tourism and recreation activity, while at the same time playing a very important role in fire protection. When open to the local traffic, they significantly supplement the public traffic networks. Costs of constructing permanent roads in forested areas are considerable, because they need to have adequate bearing capacity. Forest roads are predominantly constructed using natural or anthropogenic aggregate stabilised mechanically and chemically. A tangible parameter verifying the proper construction of road structure is provided by its bearing capacity, i.e. the capacity of the pavement to carry loads generated by traffic without excessive strains hindering normal use of the pavement or reducing its durability. Some forest road networks are also constructed as temporary roads composed of cheaper aggregates. It seems reasonable to assume different bearing capacity standards for such roads than for permanent roads.The aim of the studies presented in this paper was to develop bearing capacity standards for forest roads constructed using various technologies. The adopted research hypothesis assumes that each of the analysed technologies is characterised by a different bearing capacity required during road construction inspections. An example of such a structure may be provided by the so-called geotextile mattress and crushed stone constructed on wetland soils. When developing the standards, the analyses included the predicted traffic intensity, assumed operation time before rehabilitation is required, soil conditions and the type of construction material.Bearing capacity of the testing road sections was assessed based on values of strain moduli calculated from the static plate load tests (VSS). As a result, bearing capacity standards were obtained for structures constructed using aggregates and chemical stabilisers as well as geotextiles potentially facilitating reduction of the layer thickness without deterioration of road durability.

Requirements and practice from measuring the deformation resistance of the formation of the railway subgrade of the Slovak railways modernized line Plevník-Drienové-Bytča-Žilina

Deformation resistance of the formation of the subgrade is the main indicator of the quality of the designed structural layers of the subgrade formation. Deformation resistance is determined in Slovak Railways (ŽSR) by a static plate load test and is expressed by the modulus of deformation Es . The static load test not only verifies the correctness of the design of the type of structural layers of the body of the railway subgrade, but it is also an indicator of the quality of the performed construction works. On modernized ŽSR lines, is designed for subgrade type No. 3 and in the most unfavorable geotechnical conditions also the type of structural layers of the formation of the railway subgrade No. 6. The required value of deformation resistance at the level of the formation of the subgrade is designed with regard to the speed zone of the railway line. ŽSR corridor lines are designed for speeds up to 160 km/h, so they belong to the RP4 speed zone. Such lines also include a section of the ŽSR modernized Plevník-Drienové-Bytča-Žilina line.

Performance evaluation of construction and demolition waste aggregates as an alternative base course material in highway construction

ABSTRACT Construction and demolition (C&D) wastes are found to be the main source of unwanted materials produced worldwide. Due to the insufficient amount of high-quality fresh limestone aggregates, construction and demolition waste are used as an alternative base course material for highway construction. The stabilization of C&D recycled aggregate waste with ordinary portland cement (OPC) has been repeatedly used by the researchers to improve the performance of the base course in highway construction. The studies related to the geosynthetic-reinforced C&D waste are limited. In this study, the efficacy of geosynthetics reinforced bases was evaluated within the base course with three different base thickness (120, 150 and 200 mm). Two different infill materials, namely, C&D waste and limestone aggregates were used and plate load tests were conducted to simulate traffic loading over geosynthetic reinforced and unreinforced unpaved test sections. This study aims to present the results in terms of load versus deformation and load versus vertical stress distribution. It was observed that the C&D waste improvement factor is more than virgin aggregates (limestone aggregates). Due to the inclusion of geocell and geotextile, the average bearing capacity improvement factor enhances by 62% and the vertical stresses decrease significantly.

Wpływ stosowanych zakresów naprężeń na wartości wtórnego modułu odkształcenia oraz wskaźnika odkształcenia pospółki i kruszywa łamanego w badaniach płytowych VSS

Badanie VSS jest w inżynierii komunikacyjnej metodą stosowaną powszechnie, głównie do pomiaru nośności podłoża i warstw konstrukcyjnych. Badanie to wykorzystuje się również do oceny zagęszczenia gruntów i kruszyw na podstawie oceny stosunku wtórnego modułu odkształcenia do pierwotnego modułu odkształcenia, oznaczonego jako wskaźnik odkształcenia. Wyniki badań własnych przedstawione w niniejszym artykule poprzedzono analizą stosowanych metod badań podłoża płytą VSS w różnych krajach oraz interpretacją wyników tych badań. W celu ustalenia, jak zakres naprężeń wpływa na wartość wtórnego modułu odkształcenia oraz wskaźnika odkształcenia przeprowadzono analizę wyników badań płytą VSS nośności warstw ochronnych wykonanych z pospółki i kruszywa łamanego. Stwierdzono, że w przypadku obu materiałów istnieją silne zależności liniowe pomiędzy wtórnymi modułami odkształcenia zbadanymi przy zakresach przyrostu naprężenia 0,1 MPa oraz 0,15 MPa. Ustalono, że stosowany różny zakres przyrostu naprężeń w badaniu VSS nie ma istotnego wpływu na wskaźnik odkształcenia pospółki i kruszywa łamanego. Natomiast różny zakres tych naprężeń wpływa na wartość wtórnego modułu odkształcenia.

Model tests of freeze-thaw behavior of geocell-reinforced soils

Freeze-thaw cycles are a major cause for destabilizing pavements in cold regions. Among countermeasures for freeze-thaw damages, use of geocells to reinforce pavement bases is an effective solution in practice. However, as opposed to widespread applications, research concerning freeze-thaw behavior of geocell-reinforced bases is limited, probably due to a lack of proper devices for conducting experimental tests. This paper presents a new model-test device capable of performing both freeze-thaw tests and plate loading tests on geocell-reinforced soils. A thermodynamic numerical model was developed to assist with the design of freeze-thaw component of the device, while the design of plate loading component was developed by referring to features of existing devices. Eleven tests were run on geocell-reinforced and unreinforced sands to confirm the effectiveness of the proposed device. The test results showed the device successfully provided vertical heat transfer in sands during freeze and thaw. After five freeze-thaw cycles, geocells reduced peak frost heave and thaw settlement of sands by 18% and 34%, respectively, and increased the stiffness and bearing capacity by 40% and 253%, respectively. It was found a temperature drop occurred at the interface between cooling plate and sands, which was due to the existence of thermal contact resistance.

Avaliação do potencial de uso do deflectômetro de impacto leve para medidas de deflexão em pavimentos urbanos

O objetivo principal deste estudo foi avaliar o potencial de uso do Deflectômetro de Impacto Leve (LFWD) para medir deflexões em pavimentos urbanos. Para isso, avaliaram-se medidas de deflexões aferidas pelo LFWD, viga Benkelman (VB) e o ensaio de carga com placa (PL) em pavimentos construídos com diferentes materiais, espessuras de revestimento asfáltico e idades de operação. Determinaram-se modelos de regressão linear, que relacionaram as medidas de deflexão entre o LFWD e a VB, e o PL. Os resultados mostraram que não houveram boas relações lineares em estruturas compostas por camadas de revestimento asfáltico mais espessas, como também em estruturas com revestimento asfáltico sobre paralelepípedos. Houve boa relação linear em estruturas compostas por revestimento asfáltico mais delgado. Este estudo estimula o uso de equipamentos dinâmicos de ensaios não destrutivos para medição de deformações elásticas para o projeto de manutenção e reabilitação de vias de baixo volume de tráfego.

Effect of Geocell on the behaviour of Soil

As the use of plastic has rapidly increased in past few years, attempts are made to use it as reinforcement material to escalate the soil properties. For the present study, plastic bottles are cut and made into geocell to use it as the reinforcement to the soil. Use of plastic as reinforcement has great advantages, as it is low cost and easily available. Results of plate load tests on soil and plastic bottle reinforced soil are presented and compared. Finally, it is observed that plastic bottle reinforced soil provides improved performance when compared to that of unreinforced one. An improvement of 1.86 times the plain sand is attained when plastic bottle reinforcement was used.