Soil Embankment Research Articles

A STUDY ON THE USE OF POLYURETHANE FOR ROAD FLOOD DAMAGE CONTROL

The strength of subgrade soil or road foundation could influence the design of road pavement structures. Flood can be one of the causes of weakened subgrade and consequently road damages. Since the condition of subgrade layer is critical in the road pavement stability, a preliminary study was carried out to ascertain the use of polyurethane insertion as a stabilization mechanism in road subgrade. This study was conducted based on two types of soil that are usually used as soil embankment in road construction. California Bearing Ratio (CBR) test was conducted on the various categories of soaking days and repeated submerged conditions to determine the strength of subgrade soil with and without polyurethane layer. It can be concluded that polyurethane layer can be used to increase or maintain the strength of subgrade soil from the inundation effect.

Parametric study on the effect of structural and geotechnical properties on the seismic performance of integral bridges

In this paper practical techniques are introduced for detailed modeling of soil–pile and soil–abutment interaction effects for integral bridges (IBs). Furthermore, a parametric study is conducted to determine appropriate structural configurations and geotechnical properties to enhance the seismic performance of IBs. For this purpose, numerous nonlinear structural models of a two-span IB including dynamic soil–bridge interaction effects are built. Nonlinear time history analyses (NTHA) of the IB models are then conducted using a set of ground motions with various intensities. In the analyses, the effect of various structural and geotechnical properties such as foundation soil stiffness, backfill compaction level, pile size and orientation, abutment height and thickness are considered. The results of NTHA are then used to assess the effects of these properties on the seismic performance of IBs in terms of member forces and deformations. It is found that while the proposed modeling techniques for IBs are easy to implement in commercially available structural analysis programs, they are also computationally efficient. However, the proposed structural model may not be used to study the soil deformations along the length of the embankment. For the IB and modeling approach under consideration, the bridge seismic response is found to be insensitive to the length of the embankment and damping of the embankment soil. Furthermore, IBs built with shorter and thinner abutments as well as large steel H-piles oriented to bend about their strong axis exhibit better seismic performance.

Influence of Different Soil Properties on Shear Strength of Soil: A Review

Compacted soils in embankments of dams, and roads, dikes, liners, etc. are commonly used in geotechnical engineering. Soil variability and uncertainty of a natural soil deposit and its properties are common challenges in geotechnical engineering design. The unsaturated soil mechanics is receiving increasing attention from researchers and as well as from practicing engineers. The present work is a review of research articles related to shear strength calculations for different conditions of strata and other parameters.

Geotechnical Parameters of Soil, Considering the Effect of Additional Compaction of Embankment

The paper presents selected test results obtained during construction of multi-layer soil embankments. It also provides the analysis of a new geotechnical approach, used for construction of non-typical soil embankments, which takes into account the effect of additional compaction of individual layers. The tests were conducted in in-situ conditions. As a result of compaction of consecutive 30 filling layers with 0.30m in thickness, it was possible to develop a statistical model allowing to assess the impact of overlying (higher) layers on successive compaction of a layer of soil incorporated earlier. The obtained results allow for the assessment of the influence of compaction of the higher layers on the increased soil compaction of the lower layers.

Determination of Sandy Subsoil Stiffness on the Basis of Surface Vibration Measurement

The main aim of the study is an attempt of determination of the stiffness modulus of sandy subsoil based on analysis of data recorded during the measurements of vibrations conducted on the surface of the ground. The procedure proposed in the article is similar, to some extent, to the method of Spectral Analysis of Surface Waves (SASW). The main difference between the proposed way and the SASW method is application of a different type of a ground load, the use of accelerometers instead of geophones and application an backward analysis in place of the most frequently used in geophysics factored wavelength method. Field tests of acceleration of vibrations were carried out at measuring points located at a distance of 5 m and 10 m from the source of vibration. The Light Falling Weight Deflectometer (LFWD) was the source of vibration. Measurements of vibration were executed using measuring system produced by Siemens (LMS Scadas Recorder). The determination of the subsoil stiffness was made on the basis of obtained results in two ways. The first simple way was based on measuring the time of movement of the Rayleigh wave between the measuring points. The second way was to use the own author's computational program and backward analysis. The program based on the Finite Difference Method (FDM) enabled the description of wave propagation in the ground under the impact load. The proposed method allowed the determination of the average values of stiffness modulus of subsoil G and E. This method can be useful for analysis of the level of vibrations transmitted to the foundations of buildings. They can also be the basis of determination of the necessary stiffness parameters for soil-structure interaction analysis in various problems of dynamics of structures. It can be used to evaluate the stiffness of soil in road embankments. The method is nondestructive (needs no boreholes) and can be fully automatized.

Assessment of Guar Gum Biopolymer Treatment toward Mitigation of Desiccation Cracking on Slopes Built with Expansive Soils

Expansive soil embankments are prone to shallow slope failures caused by associated swell–shrink movements. Previous studies have confirmed that seasonal changes and corresponding volumetric changes are responsible for desiccation cracking, which is a major factor behind shallow slope failures of highway embankments. For the past few years, soil stabilization proved to be an effective way to mitigate the swell–shrink property of expansive clays. The current study addresses the feasibility of guar gum biopolymer in mitigating the swell–shrink behavior of clays and in turn making it possible to adopt them as stable geomaterials. The sustainable benefits of biopolymers far exceed the environmental benefits from conventional stabilizers that contractors typically use. This paper presents a comprehensive laboratory study, followed by finite difference modeling analysis, on biopolymeric guar gum–remediated expansive soils collected from shallow slope failure-prone areas. For this study, two dam locations, at Grapevine Lake and Joe Pool Lake, Texas, that were originally constructed with expansive soils, were considered. The engineering performance of biopolymer-treated soils was evaluated and an optimum dosage was recommended for mitigating desiccation cracking at the test sites. Slope stability analyses were conducted using Fast Lagrangian Analysis of Continua in Three Dimensions software by adopting laboratory-determined strength parameters to determine the range of the factor of safety for the slopes. The variation of the factor of safety computed with the inclusion of enhanced engineering parameters from guar gum treatments revealed the advantages of adopting this treatment.

High Speed Trains Geotechnics: What is a Tolerable Bump?

The problem of the bump at the transition between the embankment and the bridge is an important concern for railways and highways. These bumps can lead to a rough riding surface which creates discomfort at high speed and high maintenance costs. The current study addresses the problem for High Speed Trains (HST). One reason for the development of a bump is the difference in stiffness between the compacted soil embankment and the bridge typically resting on deep foundations. A 4-D finite element model, developed in LS-DYNA, was used to simulate the effect of this difference in stiffness at the transition between the embankment and the bridge. The modulus of the embankment is varied from 5MPa for a very soft embankment to 120MPa for a very stiff embankment. The bridge is considered to be rigid by comparison. This study will show that the dynamic amplification factor, DAF, defined as the ratio of the maximum dynamic rail/wheel impact force to the static load on the wheel, changes dramatically with the embankment modulus and train speeds.

Risks of Climate Change with Respect to the Singapore-Malaysia High Speed Rail System

Warming of the climate system is unequivocal, and many of the observed changes are unprecedented over the past five decades. Globally, the atmosphere and the ocean are becoming increasingly warmer, the amount of ice on the earth is decreasing over the oceans, and the sea level has risen. According to the Intergovernmental Panel on Climate Change, the average increase in global temperature (combined land and surface) between the 1850–1900 period and the 2003–2012 period was 0.78 °C (0.72 to 0.85). But should we prepare for such a relatively small change? The importance is not the means of the warming but the considerable likelihood of climate change that could trigger extreme natural hazards. The impact and the risk of climate change associated with railway infrastructure have not been fully addressed in the literature due to the differences in local environmental parameters. On the other hand, the current railway network in Malaysia, over the last decade, has been significantly affected by severe weather conditions such as rainfall, lightning, wind and very high temperatures. Our research findings based on a critical literature review and expert interviews point out the extremes that can lead to asset system failure, degraded operation and ultimately, delays in train services. During flooding, the embankment of the track can be swept away and bridge can be demolished, while during drought, the embankment of the track can suffer from soil desiccation and embankment deterioration; high temperature increases the risk of track buckling and high winds can result in vegetation or foreign object incursion onto the infrastructure as well as exert an additional quasi-static burden. This review is of significant importance for planning and design of the newly proposed high speed rail link between Malaysia and Singapore.

IMPROVEMENT OF LOOSE GRANULAR SOIL BY USING GEOGRID REINFORCEMENT

There are several uses of granular soils in civil engineering works such as but not limited to under foundations structures, subbase course of roads, unpaved roads and soil embankments. This research attempts to overcome the problems of low-quality (by means of strength) of granular soil by enhancing California Bearing Ratio (CBR) test by utilizing geogrid. The research aim's to investigate the potential benefits of using the geogrid to improve CBR of granular soil. The results of tests showed that the granular soil under study was inferior than the materials comply on class C of Iraqi specifications for granular soil material. On the other hand, using of geogrid type Tensar SS2 at 0.15H (where H the total thickness of granular material samples) improves extremely the CBR value of the granular soil as it is increased by about three times in comparison with untreated soil.

Assessment of Stability of Railway Abutment Using Geosynthetics

An approach section on an abutment is located between the soil embankment and the structure, which may cause an uneven surface due to different settlement between the abutment and the soil embankment. This study proposes a new type of wall which separates the abutment from the backfill material using mechanically stabilized wall. A new type of keystone which incorporates geotube and wire mesh is proposed and evaluated. Numerical analyses were performed to investigate the applicability of the proposed keystone type, which incorporates Geosynthetic. The maximum horizontal displacements along GRS wall faces, settlements at the top of pavement and track bed, and tensile forces applied on geotextiles under traffic loads were investigated. The results of the numerical analysis showed that the proposed wall can be used for highway and high-speed railway abutment.

Forensic Investigation of Causes of Premature Longitudinal Cracking in a Newly Constructed Highway with a Composite Pavement System

AbstractForensic investigations were conducted to identify the causes of longitudinal cracking (LC) of a newly constructed highway. The case-study highway was built with a composite pavement system and is located in a semiarid region north of the equator in Africa. During these investigations, several tests were performed, such as a visual survey of cracks, nondestructive tests, and coring. Long-term observations of soil movements and crack growth were executed. The results showed that the main reasons for surface cracking were (1) use of clayey soils as filling material, and (2) the region’s climate. Such conditions led to a cycle of nonuniform swelling-shrinkage of embankment soil, which resulted in failure of the treated base and the beginning of a well-defined cracking mechanism. The results of this investigation will allow suggestions to be proposed for immediate improvement of the zone against most defects and to implement remedial solutions for other parts.

Hubungan Teoritis Antara Berat Isi Kering Dan Kadar Air Untuk Menentukan Kepadatan Relatif

Soil stabilization can be done with a few way, by increasing soil density or compaction. Compactable soil can increase soil strength and bearing capacity to working payload. Laterite soils as embankment soil that stabilized with compacting method, influenced by water content, dry unit weight and compacting dissociation energy. To know theoretical connection between water contents, dry unit weight, degree of saturation and energy of compaction is done in laboratory with method Standard Proctor and Modified Proctor to know optimum water content zone at some Sr and determines minimum energy that needed to gets relative density of 90% ( RC 90%) so that economic compacting can be reached. From result of this research, it is gotten that optimum water content resided at Sr 75% and there is no compacting curve cuts Sr 100% ( ZAV). By using theoretical connection between dry unit weight , water content, Sr and compacting energy, it can determine the water content zone and minimum energy that needed to reachs relative density of 90% ( RC 90%).

Study on Rheological Properties of Mountains Area Coarse - Grained Soil Embankment and Settlement Prediction Method

Study on Rheological Properties of Mountains Area Coarse - Grained Soil Embankment and Settlement Prediction Method

Optimizing arching creation for Abou Muharik Tunnel in Egypt using numerical analysis

This paper investigates the arching action occurring in sand dunes and protection embankment of the “on ground” Abou Muharik Tunnel. The precast concrete tunnel is proposed to protect the planned railway line passing from phosphate rich Abou Tartour Area, and through a zone of complex chain of sand dunes in Abou Muharik. Two alternatives are proposed by the designers for the embankment of the tunnel: 1) Using compacted sand for the entire backfill around the tunnel and 2) Embedding a layer of Pneusol within the backfill above the tunnel. The paper presents numerical simulations of both designs using the Finite Elements Program ANSYS. The simulation results give insights on the arching mechanism occurring within the sand dunes and protection layers. Analysis shows that using a Pneusol layer within the protection embankment relieves around 14% of the reaction forces at the tunnel foundation. Eventually, the Marston effect on the tunnel foundation is almost eliminated. The paper also presents a parametric study to optimize the specifications of the Pneusol layer. The study shows that a 10 m wide layer with stiffness that is 20% of that of embankment soil produces most favorable straining actions in the tunnel.

Nonlinear Response of Approach Slab on Cyclic Loading

The approach slab is in the terms of structural behaviour an area element with interaction with a subsoil, where one of its edge is connected thru the hinge on the abutment of the bridge. In a simplified structural schemes it is possible to model this slab element with a hinged connection to the abutment and the subsoil interaction is represented by a spring area under the approach slab. More difficult approach of modelling the reinforced concrete slab and the subsoil interaction is by 3D soil elements with the properties of soil embankment. In both cases of those linear approaches exists few imperfections, which does not represent the real behaviour. Load from the traffic acts on the slab cyclic. Therefore special problems occur in modelling of those transition areas. By crossing vehicles and its acting in time, continuous consolidation of the soil under the approach slab is being in progress. It can possibly cause creation of the void and consequently loss of a contact between the slab and subsoil. The paper deals with modelling of the reinforced concrete approach slab and the soil interaction with a nonlinear soil element, and also response of the slab on the cyclic load. All these effects can cause changes in structural scheme, and therefore changes in a strain of the slab member. The model is trying to describe the subsoil consolidation in time. In a connection with that fact, the fatigue failures of the approach slab are examined too.

Fiber optic sensor for hydrostatic pressure and temperature measurement in riverbanks monitoring

An optical fiber sensor for the simultaneous measurement of hydrostatic pressure and temperature in soil embankments is presented. It exploits the differential strain induced on a fiber in a dual–chamber case, constituting the sensor body. The strain, either induced by the pressure or by the temperature, is optically measured by means of coherent frequency domain reflectometry and variations induced by the two physical phenomena are discriminated because of the different behavior of the two chambers. Characterization of the sensor is presented and discussed. The prototype shows promising performance: temperature and pressure sensitivities are approximately −7GHz/°C and −3.2GHz/kPa, respectively, with accuracies of 0.5°C and 0.3kPa.

Stability of Slopes and Embankments of Coarse Man-made Soils

The suitability of soils for the construction of subgrade is determined by their road-building properties. For this purpose coarse, sandy and sandy loam soils are the most suitable. Many coarse man-made soils are formed during mining. These soils undergo significant changes in composition, structure and texture of natural minerals under the influence of weather and climatic factors. Coarse man-made soils may differ by petrographic composition and metamorphism of minerals. These multi-component systems are composed of fine-grained components and large particles varying in strength, water and frost resistance. The aggregate strength characteristic was taken as an integrated criterion for the assessment of embankment subgrade based in part on the capabilities of the test and also the need for the creation of a dense structure for multi-component coarse soils. From this, a technological classification for coarse soils was developed. The problem of using coarse soil in embankments is the possibility of soil settlements occurrence due to the large space between the particles and due to the impact of weather and climate factors. For ensuring a stable structure of subgrade, such coarse soils should be either isolated from the influence of weather and climatic factors or the structure of the subgrade should be made dense non-settling properties by means of technological solutions that envisage filling the entire space between the large particles with fine-grained materials (e.g. pit-run fines). The design solutions are developed depending on the type of coarse soil. This will protect the embankment body from the effects of weather and climatic factors, namely: wetting-drying and freezing- thawing.To ensure durability and stability of the embankment slopes, technological solutions for creating a single strong structure were developed. Effective subgrade structures that take into account the characteristics of these materials and ensure their sustainability and stability were developed basing on the results of coal waste research.

Changes in Mechanical Parameters of Soil, Considering the Effect of Additional Compaction of Embankment

The paper presents selected test results obtained during construction of multi-layer soil embankments. It also provides the analysis of a new geotechnical approach, used for construction of non-typical soil embankments, which takes into account the effect of additional compaction of individual layers. The tests were conducted in in-situ conditions. The testing area constituted a foundation for a large industrial object, i.e. a clinker storage silo of storage capacity of 200 000 tons. The obtained results allow for the assessment of the influence of compaction of the higher layers on the increased soil compaction of the lower layers.

Reliability of Approach Slabs and Modelling of Transition Zones of Bridges

The approach slab is the structural member of transition zones, which compensates a different settlement of bridge abutment and a road embankment. The main reason of different settlement is the consolidation of soil under the slab and the abutment. The geometry of approach slab, its length and the thickness is defined on the basis of differential settlement of embankment and the abutment. The static behaviour of slab is defined as a slab on elastic soil. The reinforced concrete slab is supported with the line rigid support on the one edge, and the rest of slab area interacts with the soil. The civil engineers design the reinforcement in those slabs based on the simplified structural scheme, without considering the elastic area support. This scheme is the simple supported slab on the both ends. The paper is dealing with the comparing of different structural models of the reinforced concrete approach slabs. The complex models of transition zones with the brick elements of the soil and the interaction with the reinforced concrete slab with the soil embankment are compared with the simplified models used by civil engineers. The analysis was performed on the transition zone of highway bridge from Slovakia based on its geometry and the subsoil consistence. In the parametric study was compared 8 soil stiffness’s on 10 structural models.

Analysis of the filtration processes in soil embankment based on numerical modelling and temperature measurements

This paper presents analysis of the filtration processes in experimental soil embankment. The analysis is made during flooding experiments. The analysis is based on numerical modelling and temperature measurements. The measurements were performed on experimental embankment, which size is in scale 1:5 comparing to Polish typical river embankments. This experimental embankment was built in a frame of ISMOP project [1]. It was constructed by the NeoSentio company to investigate the influence of sensors installation for the filtration process and structure stability. The embankment was dry in the beginning of the experiment. The flooding and discharging process took about 8 hours. Filtration of water through the embankment caused changes of the inner temperature, which was measured by thermal sensors inside the embankment. Pore pressure sensors registered changes in water level in embankment. Furthermore, 2D numerical modelling in FLAC 7.0 software was performed. The model reflects the geometric and geotechnical attributes of the real embankment. Comparison between measured and modelled temperatures was performed. The model quite well predicts the time when water reach each sensor. But there is a difference in the rate of fall of water level. Modification the parameters of the model allows to fit the modelled data to measured values.