Design Of Road Structures Research Articles

Про тимчасове навантаження на аркові споруди з гофрованого металу під дорожнім насипом

Introduction. The issue of features of formation and practical calculation of temporary moving load from vehicles on arched structures made of corrugated metal under the road embankment is considered. These features are related to the scheme of static work and deformation of a relatively flexible structure — mainly to bending under the influence of the prevailing vertical pressure from the soil of the embankment and in the conditions of the transfer of a temporary load through the soil of the embankment, which distributes this load in a certain way. Problem Statement. In the current regulatory and methodological documents regarding the design of bridges and pipes, information on the rules for determining the amount of temporary moving load on pipes under highway embankments is limited to instructions regarding the parameters of a typical scheme of wheel loads (NK-100 or NK-80) and regarding the distribution of properties of the soil of the embankment, without setting out the methods and formulas necessary for practical calculations, which complicates the design to a certain extent. Normative and methodical documents directly related to the design of road structures made of corrugated metal also do not contain sufficiently complete and correct information on this issue.

Integrated hydrological and hydraulic modeling for predicting sediment transport in hydraulic road structure design: the case of oued ait ourir, high atlas, Morocco

Integrated hydrological and hydraulic modeling for predicting sediment transport in hydraulic road structure design: the case of oued ait ourir, high atlas, Morocco

Review of Subgrade Soil Stabilised with Natural and Synthetic Fibres

Subgrade soil is an essential component in the design of road structures as it provides lateral support to the roadway. One of the main reasons for pavement failure is subgrade settlement, which leads to a loss of subgrade strength. If the mechanical properties of subsoils are lower than required, a soil stabilisation method may be an option to improve the soil properties of the weak subsoil. Soil stabilisation is one of the techniques for improving poor subsoil, which results in significant improvement in tensile strength, shear strength and bearing capacity of subsoil. Soil stabilisation can be broadly divided into four types: thermal, electrical, mechanical, and chemical. The most common method of improving the physical and mechanical properties of soils is stabilisation with binders such as cement and lime. However, soil stabilisation with conventional methods using cement and lime has become uneconomical in recent years, so an alternative such as fibres may be sought. This review provides a comprehensive comparison of the effectiveness of natural fibres and synthetic fibres in stabilising subgrade soils.

2T3C apparatus and DIC technology to investigate the thermomechanical behaviour of the interface between bituminous layers

The bonding at the interface is seen in most road structure design methods as perfectly bonded and this ideal condition is supposed to last during the whole service life. However, the real working capacity at the interface is complex and gradually degrades because of repeated traffic load and weather conditions. A new apparatus called 2T3C (“Torsion, Traction, Compression sur Cylindre Creux” in French, or “Torsion, Tension, Compression on Hollow Cylinder” in English) was developed at the ENTPE/University of Lyon to investigate the thermomechanical behaviour of the interface between bituminous layers. The sample has two layers of similar or different materials. It has a total height of 125 mm and a wall thickness of the 25mm. The thickness was chosen small enough in order to validate the assumption of quasihomogenous stress and strain fields between inner and outer surface. The DIC technology is performed considering the three listed elements: (1) two couple of cameras are situated on two opposite sides of the sample (4 cameras in total) to take 3D images; (2) a software is employed to calculate the displacements in 3 dimensions of all points in the area of interest; and (3) the strain fields in the 2 layers and the displacement gap at the interface are computed using a method developed at the University of Lyon/ENTPE. In this paper, a focus is proposed on the viscoelastic and fatigue behaviours of the two bituminous layers and of the interface. Small and large numbers of loading cycles are successively considered in the small strain domain.

Обеспечение эксплуатационной надежности при проектировании автомобильных дорог в условиях Сибири и крайнего севера

Complex natural and climatic, unfavorable soil-hydrogeological and cryogenic conditions of Siberia and the Far North require a special approach to the design of road structures. Taking into account the prediction of climate changes, the intensity and composition of traffic flow, a number of uncertainties arise at the design stage, which can lead to an unrealistic unaccounted picture during the operation of the highway. The article presents the criteria of operational reliability, the results of forecasting and changes in the operational characteristics of highways in the life cycle. It also provides the results of geo-radar surveys on the sections of operated highways, and concerns with the main provisions of ensuring operational reliability in the design of highways in Siberia in the II and III road-climatic zones. The results of the research give the recommendations for the conditions of the Far North. They are able to ensure operational reliability with a staged position requiring additional in-depth monitoring surveys.

The Influence of Curing Temperature on the Mechanical Properties of Cement-Reinforced Sensitive Marine Clay in Column Experiments

The understanding of the mechanical properties of sensitive marine clay subgrade stabilized with cement is vital for the safe, economical, and durable design of road structures. As the curing temperature affects the cement hydration progress, it is necessary to investigate the influence of the temperature on the evolution of the mechanical properties of cement-reinforced marine clay in road construction. A column testing and relevant monitoring program were performed to study the effect of various curing temperatures (2 °C, 22 °C, and 40 °C) on the mechanical properties’ development of cement-reinforced clay within 28 days. After these cement clay samples were cured for a specific time (1, 3, 7, and 28 days), they were subjected to two mechanical tests (i.e., California Bearing Ratio (CBR) test and uniaxial compressive strength (UCS) test). The findings reveal that a higher curing temperature accelerates cement hydration and self-desiccation. Consequently, the UCS and CBR values increase with curing temperature and the strength might vary by more times, especially for early age (≤7 days) samples. The results of this study contribute to a deeper understanding of the influence of temperature on the mechanical properties of the cement-reinforced clay and thus provide practical guidance with regards to road construction in the field.

Contribution to the mechanistic-empirical roughness prediction in asphalt pavements

The guarantee of traffic conditions with safety and comfort is one of the primary aims during a road structure design. Thus,this study aims to contribute to the roughness prediction, represented by the International Roughness Index (IRI), bydeveloping models that describe the functional performance of Brazilian pavements. With monitoring actions carried out insites located in Santa Maria/RS and Rio de Janeiro/RJ, the paper sought to evaluate the IRI's evolution. The mechanisticmethodology was inserted to the study's scope by predicting the IRI evolution using the average fatigue damage, which wascalculated with FlexPAVETM software. The procedure enabled the development of a mechanistic-empirical model, basedon the initial IRI obtained after the end of the construction process and the computationally asphalt layers calculateddamage. The developed model was also validated with other sites within the Brazilian territory, which results in significantpractical applicability.

Investigation of Vehicle Stability with Consideration of Suspension Performance

The issue of movement stability remains highly relevant considering increasing vehicle speeds. The evaluation of vehicle stability parameters and the modeling of specific movement modes is a complex task, as no universal evaluation criteria have been established. The main task in modeling car stability is an integrated assessment of the vehicle’s road interactions and identification of relationships. The main system affecting the vehicle’s road interaction is the suspension of the vehicle. Vehicle suspension is required to provide constant wheel to road surface contact, thus creating the preconditions for stability of vehicle movement. At the same time, it must provide the maximum possible body insulation against the effect of unevennesses on the road surface. Combining the two marginal prerequisites is challenging, and the issue has not been definitively solved to this day. Inaccurate alignment of the suspension and damping characteristics of the vehicle suspension impairs the stability of the vehicle, and passengers feel discomfort due to increased vibrations of the vehicle body. As a result, the driving speed is artificially restricted, the durability of the vehicle body is reduced, and the transported cargo is affected. In the study, analytical computational and experimental research methods were used. Specialized vehicle-road interaction assessment programs were developed for theoretical investigation. The methodology developed for assessing vehicle movement stability may be used for the following purposes: design and improvement of vehicle suspension and other mechanisms that determine vehicle stability; analysis of road spans assigned with characteristic vehicle movement settings; road accident situation analysis; design of road structures and establishment of certain operational restrictions on the road structures. A vehicle suspension test bench that included original structure mechanisms that simulate the effect of the road surface was designed and manufactured to test the results of theoretical calculations describing the work of the vehicle suspension and to study various suspension parameters. Experimental investigations were carried out by examining the vibrations of vehicle suspension elements caused by unevenness on the road surface.

ON THE ISSUE OF ROAD AND CLIMATE ZONING OF THE REPUBLIC OF DAGESTAN

The article presents the principles of road-climatic zoning of any mountain region. Only in each specific case, depending on the location of the area in latitude, the type of vertical natural belts, it is necessary to specify the boundaries of road and climatic zones in height.
 The above proposals for assigning certain areas of the territory of the republic to a particular natural and climatic zone do not apply to those areas where there is a continuous occurrence of stony or stony soils in the upper layers.
 For such sections, an individual approach to the design of road structures should be applied in each specific case.
 Road-climatic zoning is the most effective way to refine the characteristics of soils, providing a significant improvement in the quality of design and construction of the roadbed.

Road Design on Low Bearing Capacity Soils

Soil with weak bearing capacity, like peat and organic grounds, is widespread in Latvia. During the geotechnical investigation for road reconstruction projects, in many cases the discovered soils with low physical-mechanical properties are located below the existing road structure. It is a challenge for a road design engineer to find a way how to ensure road loadbearing capacity and prevent the occurrence of various deformations. Various methods and technologies for ground structure reinforcement and stabilization are being developed worldwide. During design of road structures, it is important to analyse the geotechnical situation and to identify the main reasons why deformations could occur in the ground layers under the road structure. Each of the developed technologies for weak and unstable soil reinforcement, stabilization is designed to solve a specific problem. Inaccurately and carelessly identifying the causes of problems, road deformations can affect the performance of the recently designed road and even make the existing problem worse. The aim of this paper is to show the soil strengthening methods used in Latvia and to analyse the benefits and disadvantages of these methods.

CREDO RADON UA – INFORMATION MODEL FOR CALCULATION OF ROAD CONSTRACTION

CREDO RADON UA software provides an automated calculation of the strength of the pavement structures of non-rigid and rigid types, as well as the calculation of the strengthening of existing structures. In the article, one can see the main features and functionality of the CREDO RADON UA software, the main points in the calculations according to the new regulations. Information support of the design process includes necessary databases, informational and helping materials that make up the full support of the pavement design process. The concept of CREDO RADON UA 1.0 software is made on the use of elasticity theory methods in calculations of initial information models of pavements. Performing optimization calculations, the roadwear in CREDO RADON UA is designed in such a way that no unacceptable residual deformation occurs under the influence of short-term dynamic or static loading in the working layer of the earth bed and in the structural layers during the lifetime of the structure. The calculation algorithms were made in accordance with the current regulatory documents of Ukraine. CREDO RADON UA software allows user to create information bases on road construction materials and vehicles as part of the traffic flow for calculations. The presented system of automated modeling makes it easier for the customer to control the quality of design solutions, to reasonably assign designs to layers of reinforcement, to quickly make comparisons of calculations of different designs for the optimal use of allocated funds. Prospects for further improvement of the program should be the results of theoretical and experimental studies on filling the databases, which are used as information support for automated design of road structures. Keywords: CREDO RADON UA, road, computer-aided design, repair project, road pavement, strengthening, construction, rigid pavement, elasticity module, a transport stream, calculation method, information support, dynamic or static loading.

Monitoring of moisture and salinity content in an operational road structure by electrical resistivity tomography

ABSTRACTMoisture dynamics in road systems significantly affect road structure design and maintenance. This study analysed moisture dynamics in a cross‐section of motorway (the E18) in Sweden during a 1‐year period throughin situmonitoring using electrical resistivity tomography (ERT). The monitoring methodology was assessed since resistivity can provide a good proxy for monitoring moisture in the road structure. Monthly electrical resistivity was calculated by inverting resistivity data along a pre‐installed electrical resistivity line beneath the surface asphalt layer of the road at the test site. The electrical resistivity data were then statistically analysed and correlated with local climate data, that is precipitation and temperature, and with ground parameters such as moisture content. The results showed high variation in resistivity in the road surface layer and road shoulders depending on weather conditions, water flow and other surface activities. In general, negative correlations between electrical resistivity and precipitation were observed. The results also indicated possible retardation of de‐icing salt after accumulating in the top layer during winter. These findings advance understanding of the moisture dynamics in roads and can help improve pavement design in response to future climate change.

Design Characteristics of Road Structure Reinforced with Cell Geosynthetic Materials with Account of Dynamic Load Impact

Modern highways are exposed to intensive transport loads, which require strengthening of the road structure and considering the dynamic load action on design characteristics of materials. The studies define quantitative changes of strength and strain characteristics of the road structure materials depending on amplitude of oscillations under dynamic loads. Subject to the road structure design and materials used, the strength of soil subgrade, for example, can decrease under vibration by 20-30% as compared to the design value defined without taking the vibration factor into account. The use of cell geosynthetic materials in the road structure allows improving its stress strain behaviour within the range of 5% - 15%. To that end, layers of less stiff material should not be placed above stiff layers reinforced with cell geosynthetic materials.

Implications of Road Structure Design Using Different Approaches

The purpose of this paper is to comparatively study the design of a road structure, using parameters provided by standards and their practically measured counterparts. This aspect has multiple consequences, and we emphasised mainly the economical costs and the environmental impact. The location of our study is the Western edge of the city of Cluj Napoca, Romania. Using the traffic data provided by a weigh-in-motion (WIM) system installed on site, we evaluated a series of parameters used for the design of road structures. These parameters are also provided by Romanian standards, and we used their values in our comparative approach. The aim was to establish which procedure provides the best solution, considering different theoretical and practical approaches. After setting up five work hypotheses, we applied the standardised road design procedure. We applied the geotechnical, climatic and hydrological data to establish the bearing capacity of the soil. We chose a semi-rigid road pavement and we verified the 3 (three) eligibility criteria. We obtained different results for the hypotheses we considered. The study emphasises the technical and economical aspects, providing at the same time an environmental point of view. The results we obtained support the idea that WIM traffic data is a useful tool for road pavement design, as long as traffic conditions are similar for the studied sectors. Using the effective traffic values as the basis for pavement design leads to economical advantages and less harmful effects on the environment.

The Effect of Utilization of Geogrids on Reducing the Required Thickness of Unpaved Roads

The inadequacy of many existing roads due to rapid growth in traffic volume provides a motivation for exploring alternatives to existing methods of constructing and rehabilitating roads. The use of geosynthetics to stabilize and reinforce paved and unpaved roadways offers one such alternative. Many studies were conducted to evaluate the improvements associated with geogrid reinforcement of pavements. It is widely believed that geogrid reinforcement of roadways can extend the pavements service life and/or reduce the pavements structural thickness. This paper examines a method to compare traditional pavement structure designs, absent of geosynthetics, to pavement structure designs incorporating geosynthetics. At first, a specific unpaved road structure design is presented with recommended corresponding traditional road structure components. The road structure is then re-examined incorporating newly developed, reengineered geogrid. Finally, related costs with this particular design are outlined, analyzed and compared. In this case, cost savings achieved by using geogrid are substantial.

The Equivalent Stress Contrast Analyse of Inverse Structure and General Structure Asphaltum Pavement

Based on the multi-layer elastic system theory , it was elicited that the top basic-layer rigidity was a main determinate factor for the surface-layer bottom maximal equivalent stress. And the more basic-layer rigidity, the less surface-layer bottom maximal equivalent stress, showing the more the partake action of basic-layer to the surface-layer bearing axis load. On the side, bearing the same axis load, the stress passed to groundwork from the inverse structure was most compared with the other structures. So the inverse structure has no predominance in the road structure design.

The Analysis and Research on the Reliability of Concrete Pavement

As the uncertainty of the influencing factors including the vehicle load and road environment and the complexity of road structure design parameters making the structural design of concrete pavement does not match with the actual existing situation, therefore, how to further improve the existing pavement design methods and how to scientifically and reasonably evaluate the reliability of the existing pavement performance have been a hot issue among academics and engineers at home and abroad. This paper analyzes and summarizes results of recent studies on the basis, combining with the actual situation of concrete pavement project, and carries out a more in-depth systematic study on the reliability analysis of concrete pavement. By studying the basic theory of engineering structure reliability, this paper proposes analysis methods of pavement reliability which are appropriate for the characteristics of pavement structure.

Civil engineering for passage of fish and fauna

This paper summarises the key issues affecting the design of road structures that are required by an environmental report to be “’fish or fauna friendly”. The paper was prepared to help civil engineers understand these eco sensitive issues. It recommends civil engineering design parameters, choice of structural form and structure opening sizes, construction concepts and engineering design detailing of waterway bridges and culverts, road underpasses using bridges and culverts, and road overpasses using land bridges and canopy links – to best enable passage of various species. Also given are fishway design parameters, details of protective measures against predators, exclusion fencing and bat roost installation.

Thermo-viscoplastic law for bituminous mixes

Bituminous mixes have rheological properties which depend on strain amplitude level. Their strongly viscous behaviour is linear for small strain level (some 10 -5), then non-linear for higher strain level. A maximum stress is reached at failure, which can be fragile (cracking) or ductile (flow). Moreover, this behaviour strongly depends on temperature. The thermo-viscoplastic law, developed at Ecole Nationale des TPE for bituminous mixes, is presented. This law introduces the various experimental observations: a general linear viscoelastic behaviour in the small strain tange, non-linearity and viscoplastic flow. The effect of the temperature is described as well for small strain levels, where time-temperature superposition principle is applied, as for larger strain levels. This law is able to model the thermomechanical coupling phenomena, in particular, the Termal Stress Restrained Specimen Test (TSRST). TSRST simulations show the influence of non-linearity on the thermal stress evolution induced by monotonic or cyclic temeprature variation. A good simulation of this phenomenon is important for design of road structures. (A)

Thermo-viscoplastic law for bituminous mixes

ABSTRACT Bituminous mixes have rheological properties which depend on strain amplitude level. Their strongly viscous behaviour is linear for small strain level (some 10−5), then nonlinear for higher strain level. A maximum stress is reached at failure, which can be fragile (cracking) or ductile (flow). Moreover, this behaviour strongly depends on temperature. The thermo-viscoplastic law, developed at “Ecole Nationale des TPE” for bituminous mixes, is presented. This law introduces the various experimental observations: a general linear viscoelastic behaviour in the small strain range, non-linearity and viscoplastic flow. The effect of the temperature is described as well for small strain levels, where time-temperature superposition principle is applied, as for larger strain levels. This law is able to model the thermomechanical coupling phenomena, in particular, the Thermal Stress Restrained Specimen Test (TSRST). TSRST simulations show the influence of non-linearity on the thermal stress evolution induced by monotonic or cyclic temperature variation. A good simulation of this phenomenon is important for design of road structures.