Road Embankment Research Articles

Conceptual fuzzy-based decision support tool for soil improvement under highway embankment - a case study of HaNoi–HaiPhong expressway

ABSTRACT In this research, a fuzzy rule–based decision support (FRBDS) tool is developed to assist selection of ground treatment techniques for road embankments. Using input variables such as embankment height, geological condition and soft soil thickness, the FRBDS evaluates the ground treatment level, based upon which the highway engineer determines a suitable treatment method taking into account project constraints. In the case study, the FRBDS is applied for a 10-km package of HaNoi–HaiPhong expressway construction project and is evaluated in comparison to expert judgements. The results show that the treatment methods provided by the two approaches are similar for 36 out of 52 sections of the package, but the FRBDS provides more consistent and rational solutions. In particular, the FRBDS significantly reduces technological fragmentation. It can be concluded that the FRBDS is a useful tool that establishes structured innovative solutions to improve the quality of decision-making for large transportation projects.

Assessing combined analysis of electrical resistivity tomography and multichannel analysis of surface waves for ground improvement assessment near by-pass road, Silchar, Assam

Soft clayey soils are generally improved by the consolidation process. The different improvement techniques which are in vogue include the use of stone columns, sand drains with and without preload and prefabricated vertical drains. Upon improvement, the soft soil attains a higher strength and better resistance to excessive settlement. The extent of this improvement of the soft soil is measured through different in-situ tests including Standard Penetration Test (SPT), Cone Penetration Test (CPT) and Pressuremeter Test. Most of these tests are invasive and require boreholes for the collection of soil samples. Geophysical tests can scan the entire area within a short time and can accurately interpret the extent of the improvement depending on the expertise of the investigators. Sometimes a combination of two or more geophysical tests is suitable for an accurate prediction of any change in soil properties. The present study is an attempt to measure the effect of ground treatment by implementing two types of geophysical tests, namely, Electrical Resistivity Tomography (ERT) and Multichannel Analysis of Surface Wave (MASW) near a by-pass road in Silchar, Assam. The tests were conducted on a newly constructed road embankment that had undergone excessive settlement and was subsequently treated with stone columns with a preload. Both the geophysical tests showed improvement in soil properties as well as in the bearing capacity of the original soft soil. A bore log survey was also carried out before the improvement work to validate the results of the geophysical tests. Existing correlations among geophysical properties and soil properties were used to obtain the effect of improvement. It has been observed that geophysical tests can easily be carried out to accurately calculate the effect of improvement of soil properties. A combination of two or more geophysical methods yields a better understanding of the post-treatment results.

The Behavior of Stabilized Reinforced Soil for Road Embankments Application

The Behavior of Stabilized Reinforced Soil for Road Embankments Application

Comparing Several Different Numerical Approaches for Large Deformation Modeling with Application in Soil Dynamic Compaction

Dynamic compaction (DC) is vastly utilized to improve the strength characteristics of the soils. To predict the soil deformations derived from the DC operations, usually numerical simulation analysis is applied. For the conduction of such simulations, several numerical approaches with different elemental formulations can be used. From the perspective of finite element analysis (FEA), there are four main formulations including the Lagrangian, Arbitrary Lagrangian-Eulerian (ALE), Coupled Lagrangian-Eulerian (CEL), and Smoothed Particle Hydrodynamic (SPH). In this research, a comparative study has been conducted to evaluate the computational efficiency of those four approaches in the prediction of soil large deformations during the DC operations. To do this, for a DC operation executed in a road embankment construction project in China, the real field data was compared to the results obtained from the numerical simulations via the ABAQUS program. The findings demonstrate that of all those approaches, the Lagrangian approach delivers the minimum accuracy of the predicted results, albeit with the least running time. In contrast, the ALE formulation predicted closer estimations of soil deformations although it was found to be less time-efficient. Interestingly, the CEL and SPH approaches predicted the soil deformations with the maximum degree of accuracy whereas they were not as time-efficient as the Lagrangian approach. To address this issue, a hybrid model of Lagrangian and SPH formulations was constituted to satisfy the maximum accuracy with the minimum running time. Such a hybrid model is highly applicable for the accurate prediction of soil large deformations during the DC operations.

Suitability analysis of vertically installed scoria gravel drains for enhancing consolidation performance of clayey ground

In alleviating challenges associated to long-lasting consolidation of clay, highly permeable materials such as sand and crushed aggregate are used as drain. Despite the fact that granular vertical drains are effective in shortening the prolonged consolidation period of clay, limited information exist regarding applicability of scoria gravel as vertical drain that no concisely documented information is observed in literatures. This study hence aimed at evaluating suitability of scoria gravel as vertical drain in perpetuating consolidation process of soft clay under road embankment. Finite element-based simulation was used to model the drains. To incorporate the effect of gradual load increment on consolidation rate, staged construction approach was employed. Various dimensions of scoria vertical drain (SVD) have been considered to investigate the effect of dimension parameters. Besides, comparison has been made between performances of SVD and crushed aggregate drains (CAD) in impacting the consolidation process. The numerical analysis result revealed that provision of group of SVD considerably accelerated consolidation rate. With increase in drain diameter, the consolidation rate goes increasing whereas it is inversely related to increase in drain spacing. For SVD installed at spacing of 2 m, diameter of 0.4 m and length of 8 m any arbitrary settlement magnitude is achieved 25 days earlier than the case without drain. No considerable difference was witnessed in performance of the square and triangular installation patterns though the consolidation rate remains slightly faster in the case of triangular installation. In speeding up consolidation rate, SVD was observed to perform slightly better than the CAD.

Is Obliterated Land Still Land? Tenure Security and Climate Change in Indonesia

Both human activities and climate change have changed landscapes significantly, especially in coastal areas. Sea level rise and land subsidence foster tidal floods and permanent inundations, thus changing and limiting land use. Though many countries, including Indonesia, are aware of these phenomena, the legal status of this permanently inundated land remains unclear. Indonesia refers to this land legally as obliterated land. This qualification makes former landowners uncertain, as it does not recognize their previous land rights, and creates disputes during land acquisition. In view of policy pressures to develop large-scale projects, the government often fails to include obliterated land legally during land acquisition processes for these projects. This causes unfair and disputed compensation for those former landowners. Current scientific discourses do not yet address this legal quandary. This study therefore has the following three aims: (1) to describe the legal, institutional and procedural contradictions related to obliterated land; (2) to assess the validity of right of the owners whose land parcels are permanently inundated; and (3) to formulate a responsible and tenure responsive policy to deal with obliterated land. We investigate these questions for the construction of a toll road and sea embankment in Kecamatan Sayung, Kabupaten Demak involving obliterated land. We reviewed policies, regulations and documentations related to coastal land and disaster management, and the implementation of land acquisition. We used geospatial data to visualize the ways in which and locations where landscapes, land parcels and land right changed. We determined that legal uncertainty leads to policy inconsistencies in handling obliterated land, specifically during land acquisition. Additionally, former landowners suffer from the legal gaps to establish clarity of land tenure, which prevents them from receiving any compensation. We suggest a law revision that considers the social–historical aspects of land tenure when defining obliterated land. The law should also provide for a fairer and more just compensation for former landowners during land acquisition processes.

Comparison of the Number of Compactor Passes and the Constrained Modulus of a Compacted Volcanic Soil

Volcanic soil is often used as fill material in road embankment construction in Java island-Indonesia. An understanding of the engineering properties of compacted volcanic soils is needed, especially during the preliminary design phase and during the detailed design phase of the road embankment. Carrying out a field compaction trial test will significantly assist in the design of the compaction process of the road embankment construction. Selecting the correct number of passes from the compactor and the engineering properties of compacted volcanic soils can be obtained from field compaction trial tests. Constrained modulus is one of the engineering properties that can indicate the stiffness of the fill material used in a road embankment. This study aims to determine the constrained modulus of compacted volcanic soil and compare it to the number of passes of a compactor from the field compaction trial test. The volcanic soil used in this study is classified as pumiceous tuff, which is derived from older volcanic rocks. The highest value of the oedometer modulus of compacted volcanic soils is 10.38 MPa which comes from eight (8) times passes of smooth drum roller conducted on field compaction trial test.

Mechanical properties and heavy metal leaching behaviors of municipal solid waste incineration bottom ash as road embankment fillings

With the development of economy and urbanization, the natural gravels and sands for new road construction materials encountered severe shortage issues in recent decades. In the meantime, the municipal Solid Waste Incineration bottom ash (MSWIBA) is regarded as a feasible alternative of mined nature aggregates due to its similar mineralogical, physical and chemical characteristics. However, the uncertainties of long-term service performance and potential environmental pollution risk of MSWIBA prevent its widespread applications in road constructions. For these reasons, this paper investigates the resilient modulus and permanent deformation properties by the repeated load triaxial test at different moisture contents, and examines the long-term environment influence using leaching tests on the samples after subjecting to 5 freeze-thaw cycles and samples after one year weathering. Besides, the existing resilient modulus and permanent deformation prediction models of unbounded granular materials are evaluated for their applicability on MSWIBA. The test results indicate that the MSWIBA shows obvious stress-dependence and moisture-dependence in resilient modulus and permanent deformation behaviors. Moreover, the existing resilient modulus and permanent deformation prediction models with stress and moisture dependence are feasible for MSWIBA as well. Additionally, heavy metal leaching concentrations obtained from column test can meet the standard of surface water quality class V in China. This work is expected to benefit the design work and provide the insight of performance of MSWIBA as road embankment material, and promote its further widespread application in road construction.

CO2 Impact Analysis for Road Embankment Construction: Comparison of Lignin and Lime Soil Stabilization Treatments

The last decade has witnessed increased attention toward products, services, and works with reduced environmental impacts. In the field of road construction, the use of alternative materials, wastes, or by-products obtained from industries is attracting considerable interest. The Life Cycle Assessment (LCA) is a powerful project-level tool that allows the assessment of the environmental impacts of a road infrastructure, from raw materials production to end of life phase. In this study, the environmental impacts (in terms of global warming potential-GWP) of an embankment construction project are investigated by a cradle-to-gate approach. The analysis focuses on all the processes involved in the construction of an embankment section, from the base to the preparation of the pavement formation level. The results are provided for two different road types and two different stabilization methods, including the use of lignin and lime. All processes that contribute towards global warming are investigated and described in detail. The most important finding of the LCA, in terms of GWP, is that the production of materials is the phase that contributes the significant share of the total environmental impact (more than 90%) for all scenarios. The lowest production-related emissions can be recorded for the scenarios involving lignin treatment for the stabilization of the embankment body. Furthermore, the percentage increase in GWP ranges between 51% and 39% for transportation activities and 10–11% for construction activities, comparing the scenarios including lime stabilization with the scenarios involving lignin treatment.

Behavior of Low Height Embankment Under Earthquake Loading

Low height embankments are widely used as road embankments for highways and rural roads in India. Sometimes, the construction of such types of embankments on soft foundation soil becomes mandatory. In addition to the problematic soft foundation soil, seismic excitation might also play a significant role in the stability of such an embankment. The present study analyses the response of a low height embankment with soft foundation soil under earthquake loading. Numerical simulations have been performed using FLAC2D program. A stiffer half-space with higher shear wave velocity (Vs) has been considered below the soft foundation soil and the earthquake loading has been applied at the bottom of this stiffer half-space. Simulation has been performed considering two different thicknesses of soft foundation soil. In addition to that, three different levels of earthquake shaking and Vs of the stiffer half-space have been considered in the analysis. Results have been presented in the form of PGA amplification, excess pore water pressure, horizontal, vertical static/seismic displacement, etc.

Causes of Landslides in Road Embankment with Retaining Wall and Pile Foundation: A Case Study of National Road Project in Porong-Sidoarjo, Indonesia

This study was conducted to determine the cause of landslides in the toll road embankment of the national road project in the Porong-Sidoarjo area. The landslide was observed only on the north side of the embankment, with a maximum height of 7.8 meters from the subgrade despite the reinforcement with a retaining wall and pile foundation. The land shift and subsidence on the Northside led to a decline in the embankment elevation and the displacement to a maximum depth of 3.50 m. Back analysis through the limit equilibrium method was used to determine the strength of the existing reinforcement against the landslide. The results showed that the heavy rain was indeed one of the causes of landslides in the location, while the main cause was the depth of soft soil, much deeper than those in the surrounding locations. This is why a severe landslide was recorded on one side of the embankment. Moreover, the existing anti-slide pile reinforcement was discovered not to be sufficient due to its shallower length compared to the area of the landslide, and this was associated with the absence of overall stability analysis in this design. The findings showed that it is necessary to conduct a comparative study between the overall stability and the active and passive forces analyses for the soil to produce the safest design required to avoid landslides.

Consolidation Attributes and Deformation Response of Soft Clay Reinforced with Vertical Scoria Drains under Road Embankment

Application of vertical drains in soft clay soils is a common practice widely known to facilitate the consolidation rate. To overcome the adverse impact of a long-lasting consolidation process, highly permeable materials such as sand and crushed aggregates are used as drains. However, limited information exists regarding the applicability of scoria gravel as a vertical drain that no concisely documented information is observed in the literature. This study hence aimed at investigating suitability of scoria as a vertical drain in perpetuating the consolidation process of soft clay under highway embankment. Finite element-based numerical simulation was used to model the drain. The model was carried out by using 3D version of Plaxis software. In order to incorporate the effect of gradual load increment on the consolidation rate, the staged construction approach was employed. Both the square and triangular installation patterns were considered in the model in order to explore the critical effects of the drain installation pattern on the rate of consolidation. The numerical analysis also included varying dimensions of the vertical drain so as to investigate the effects of the dimension parameters of the vertically installed scoria drains. The conducted numerical analysis revealed that the rate of consolidation was considerably accelerated with provision of a group of scoria drains. With increase in the diameter of the drain, the consolidation rate increases, whereas the consolidation rate is inversely related to increase in drain spacing. For the drain installed at a spacing of 2 m, a diameter of 0.4 m, and a length of 8 m any arbitrary settlement magnitude is achieved 25 days earlier than the case without drains. Besides, incorporation of scoria drains lessens the pore pressure developed. The comparative analysis conducted on the effect of drain arrangement revealed that no considerable difference was witnessed in the performance of the square and triangular installation patterns even though the consolidation rate remains slightly faster in the case of the triangular installation pattern.

Contribution of Electrical Resistivity Tomography to the Anticipation of Potential Disasters: Case of Pipe Ramming Works Under Road Embankments

Contribution of Electrical Resistivity Tomography to the Anticipation of Potential Disasters: Case of Pipe Ramming Works Under Road Embankments

Summary of the Soil Reinforcement Technical Committee Special Session (IGS TC-R)

This document provides a summary of the different topics presented at the Special Session organized by the International Geosynthetics Society (IGS) Technical Committee on Soil Reinforcement (TC-R). This Special Session brings together very interesting studies regarding soil reinforcement in the field of geosynthetics. Studies presented include topics both from theoretical and practical points of view of reinforcement geosynthetics including general products and applications, cases studies on road embankments under challenging site boundary conditions, research on deterministic and probabilistic design of reinforced fills over voids, numerical analysis of reinforced soil wall structures, encased granular column technique, and geosynthetic-reinforced bridge abutment behavior.

ПРИМЕНЕНИЕ АРМОЭЛЕМЕНТОВ ИЗ ПЕРЕРАБОТАННОГО ДРОБЛЕНОГО БЕТОНА ДЛЯ СТАБИЛИЗАЦИИ ВОДОНАСЫЩЕННЫХ ИЛИСТО-ГЛИНИСТЫХ ГРУНТОВ

The improvement of fully saturated silty clay soil using columns of recycled crushed concrete is the subject of this paper's laboratory model studies. This study is being done to examine how recycled crushed concrete affects settlement control and bearing capacity. The research also examined the variation in subgrade modulus as well as the cause of a shallow circular footing's failure on soil where silt clay layer soil had been substituted with recycled broken concrete. The results demonstrated that combining both a partly replaced column of silty clay soil and a column of recycled crushed concrete significantly improves load bearing capability. The approach used may drastically alter the footing's stress displacement curve when it is resting on silty clay soil, reduce settlement, and make the replacement soil block within the container act as a deep foundation. Consequently, a foundation supported by silty clay may have its bearing capacity failure mechanism changed at the top of a column constructed of recycled crushed concrete, from exclusive settling to general bearing capacity failure. The use of fills with shattered concrete in them, whether natural or manmade, is growing. Hence, research into the bearing and deformation properties of this material is important for application areas such road construction, soil replenishment, and embankments.

Lightweight geo-bead fill to prevent soft ground deposit failure

As a foundation for transportation infrastructure, soft ground has limited bearing capacity and high compression. To prevent embankment failure, lightweight material is suggested. In the construction of road embankments, EPS can be regarded as an environmentally sustainable lightweight fill material. The study's goal is to create a formula for GB (Geo-bead) concrete mixing as a lightweight fill ingredient. Several tests are performed on the material specimens, including bulk density, interface shear strength, unconfined compression, and a SEM of the composite material. The tests were designed to determine the physical and mechanical qualities using GB percentages (20%, 30%, and 40%). Composite material has a lower density than compacted sand. The friction angle falls between the adhesion of GB-GB and GB-cemented sand. A ductile failure pattern develops because the bond between cement paste and GB is less than that between cement sand. The composite material's CBR passed embankment specifications. In the case of an embankment on soft soil, the 2D FEM analysis expressed settlement by compacted sand and lightweight fill material. Lightweight geo bead backfill decreases soft soil settlement, preventing failure.

Design characteristics of road embankments made of sandy soils

Sandy soils are widespread all over the world, including in Uzbekistan, and they are widely used in the construction of highways. Therefore, several regulatory documents have been developed that normalize their design characteristics. However, in the existing regulatory documents, the design characteristics of sandy soils of road embankments of highways used in the design of road coverings (modulus of elasticity E, angle of internal friction φ, specific adhesion C) are not normalized depending on the degree of compaction, calculated humidity and the content of dusty and clay particles in such soils. To solve these problems, special laboratory and field studies were conducted, the results of which are given in this article.

Consolidation settlement prediction and monitoring of toll road embankment at STA 23+650 Semarang–Demak Toll Road section

The development of toll road projects in Indonesia is experiencing rapid growth. However, due to the large number of toll roads being constructed over soft soil areas, it is crucial to address the issue of consolidation settlement. This is because settlement can lead to differential or excessive settlement, which potentially damages the structures built on such soil. Unfortunately, consolidation settlement on soft soils is a time-consuming process. Thus, a consolidation acceleration method is needed, one of which is to use a combination of PVD–Preloading. This method can also increase the soil’s bearing capacity, thereby contributing to the preservation and protection of systems that support human activities while maintaining a balance with nature. Therefore, this study aims to investigate consolidation settlement employing PVD–Preloading methods. The analysis focused on a case study conducted at STA 23+650 of the Semarang-Demak Toll Road section. The analysis employed the Asaoka method, integrating field monitoring instruments, along with the Terzaghi method for one-dimensional consolidation. The results showed that the settlement results from the Asaoka and Terzaghi methods correlate with the settlement plate instrumentation in the field.

Unsaturated modelling, testing and monitoring towards the rehabilitation of a slope on National Route 3, KwaZulu-Natal, South Africa

The stability of over-steep road embankments often worsens with time. In many cases the slope deterioration can be ascribed to continual downslope creep of a surficial layer of soil that has been affected by infiltration of rainfall. Such infiltration reduces the suction in the surficial layer interacting with the environment. With every season the surficial layer moves further downslope, often resulting in cracks in theslow lane and placing structures constructed at the crest of fill slopes in potential jeopardy. A slope on the National Route 3 (N3), in the South African Province of KwaZulu-Natal, constructed at roughly 40° from the horizontal showed signs of distress in the slow lane many years after construction. The rehabilitation of this slope required stabilisation design using unsaturated soil testing, modelling, and in-situ suction measurement. The slope was stabilised using soil nails, a high-tensile steel mesh, and a suction measurement system was installed. An overview of the emergency works design, subsequent investigation, and monitoring is provided in this paper. It was found that the suction profile determined by transient finiteelement analysis matched well with the measured suction profile and provided a good basis for the emergency design works prior to full investigation.

DIAGNOSTIC OF THE FACTORS REDUCING THE STORAGE CAPACITY OF THE TOUKOMTORE DAM IN BURKINA FASO

The Toukomtore dam in Burkina Faso was built as a road embankment to meet the water needs of the populations of the commune of Koubri. The dam's watershed is not immune to the various climatic and anthropogenic pressures that have caused it to fill up. The objective of this study is to identify the sources of sediment supply to the dam. To do this, the study relies on documentary research, individual interviews with agents of the deconcentrated technical services of the State and users as well as field observations. The results of the study reveal that the sediments in the dam basin come from intense gullying areas, bare areas, bank erosion, market gardening plots and local drains, but also from aggregate extraction sites and brick factories. The results also show that the basin of the dam has lost its initial capacity of reception due to the phenomenon of filling. These results provide indicative elements on the potential origin of the sediments of the dam and are useful for the implementation of the recommendations that have been formulated.