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Abstract: Chip seal pavements, consisting of one or more layers of asphalt binder and fine aggregate, can be mechanically characterized as a surface treatment that enhances evenness and trafficability. This paper examines the geotechnical aspects of chip seal applicability compared to traditional hot mix asphalt pavements. An analytical model was employed to design unpaved roads and determine the required thickness of unbound layers. Eight optimization models were developed for hot mix asphalt pavements and four for chip seal pavements, aimed at achieving optimal designs for various input parameters. These outcomes were used to conduct a multi-parametric analysis, incorporating an optimization loop for each combination of design variables. The results indicate that, under low traffic conditions, a chip seal pavement structure can be up to 40% less expensive than an optimal hot mix asphalt pavement structure, particularly when the subgrade has low bearing capacity and is exposed to unfavorable climatic conditions. However, at medium traffic loads, with good subgrade bearing capacity and favorable climate, the chip seal pavement structure incurs costs that are 25% higher than those of the hot asphalt pavement structure. In addition, chip seal pavements should always be designed with integrated geosynthetic reinforcement to minimize construction costs, and chip seal is not as sensitive to frost as hot mix asphalt.
Keywords: chip seal, hot mix asphalt, pavement design, cost optimization
Published in DKUM: 10.12.2024; Views: 0; Downloads: 4
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Abstract: Steep slopes in soft rock are characterized by their susceptibility to instability (rockfall, rockslide) due to weathering and erosion of the slope surface. This article deals with the problem of adapting to the increasing height of the scree slope. The construction of a retaining wall in a scree slope in front of a slope of soft rock with a steep face, where a very rapid weathering and erosion process of weathered material takes place, and the simultaneous deposition of material in front of the steep slope is a common solution. Changes in the geometry of the slope and the front scree are taken into account, and at the same time, sufficient safety against rockfall must be ensured. The analysis is shown on a specific example of a steep flysch slope near Split, Dalmatia. The retaining wall solutions are compared in terms of function, cost and sustainability. The construction of a single colossal, reinforced concrete retaining wall shows that this solution is not feasible due to the high construction costs and CO2 emissions of the retaining wall. A model was therefore developed to determine the height of the retaining walls for different construction time intervals and distances from the original rock face. The critical failure modes were investigated for various retaining wall solutions with regard to the highest degree of utilization of the resistance, which also allows the cost-optimized solutions to be determined. By building two or more successive retaining walls at suitable intervals and at an appropriate distance from the original rock face, construction costs and CO2 emissions can be significantly reduced.
Keywords: retaining wall, erosion, rockfall, steep slope, flysch, sustainable design, cost optimization
Published in DKUM: 09.12.2024; Views: 0; Downloads: 2
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Abstract: This paper presents the design of geosynthetic reinforced flexible pavements and their modification by incorporating waste materials into bonded and unbonded layers of the pavement structure. The optimal design of flexible pavements was achieved by minimizing the construction cost of the pavement. The incorporation of waste materials into the pavement structure affects the material properties. Therefore, along with the traffic load, the effects of the material properties of the asphalt concrete, base layer, sub-base layer, and subgrade were analyzed in terms of pavement structure costs and CO2 emissions of materials used in pavement construction. In addition, a comparison was made between pavements with and without geosynthetic reinforcement in terms of design, optimum construction cost, and CO2 emissions. The use of geosynthetics is even more effective in pavement structures that contain waste materials in an unbound layer, both in terms of cost and CO2 emissions. The minimum value of the California Bearing Ratio of the subgrade was determined at which the use of geosynthetic reinforcement for pavement structure with and without the inclusion of waste materials is economically and sustainably justified. The use of geosynthetics could result in a 15% reduction in pavement structure cost and a 9% reduction in CO2 emissions due to the reduced thickness of unbound layers. In addition, reducing the CBR of the unbound layer from 100% to 30% due to the inclusion of waste materials implies a cost increase of up to 13%. While the present study is based on an empirical pavement design method in which pavement thickness is limited by the pavement thickness index, the same minimum thicknesses are obtained in the optimization process regardless of whether the objective function is the minimum construction cost or minimum CO2 emissions.
Keywords: pavement design, waste materials, optimization, minimum construction cost, CO2 emissions, geosynthetics, waste management
Published in DKUM: 18.09.2023; Views: 644; Downloads: 51
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Abstract: Diplomsko delo analizira uporabo geosintetikov pri izboljšavi in armiranju tal. V nadaljevanju na kratko opišemo temeljenje in splošne informacije o geosintetikih. Za tem sledi opis postopka in primer izračuna nosilnosti tal pod temeljem brez armiranja zemljine, z izboljšavo zemljine in z armiranjem zemljine. Na koncu sledi primerjava rezultatov in presoja, pri katerih pogojih so izboljšave in armiranje zemljine smiselne.
Keywords: plitvi temelji, armirana zemljina, geosintetiki, nosilnost
Published in DKUM: 20.01.2023; Views: 683; Downloads: 101
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Abstract: Diplomska naloga prikazuje izračun posedka pod enakomerno brezkrajno pasovno obtežbo, končni čas posedanja ter časovni razvoj posedka. Izračun posedka je bil izračunan z analitično metodo, ki temelji na srednjem modulu stisljivosti. Numerična analiza posedka pa je bila izvedena z računalniškim programom Plaxis, ki temelji na metodi končnih elementov. V uvodnem delu so opisane nekatere osnovne zakonitosti mehanike tal in modeli za simulacijo odziva zemljine na spremembo napetosti. V nadaljevanju je prikazan analitični izračun časovnega razvoja posedka z obrazložitvijo uporabljenih metod in enačb. Prikazani pa so tudi koraki modeliranja v programu Plaxis, ki so potrebni za numerično analizo časovnega razvoja posedka. Izvedena je primerjava rezultatov analitične in numerične metode na podlagi velikosti posedka in končnega časa posedanja. Rezultati analitične in numerične analize izkazujejo veliko stopnjo ujemanja, saj so bili izračuni izvedeni na podlagi enakih materialnih lastnosti. Numerična analiza pa vendarle podaja natančnejšo oceno posedka in končni čas posedanja, saj je pri numerični analizi zemeljski pol-prostor razdeljen na manjše elemente kot pri analitični metodi izračuna posedka. Računalniški program prav tako omogoča natančno določitev začetnih efektivnih napetosti in spremembo napetosti, ki so posledica obremenitve ali konsolidacije.
Keywords: posedek, konsolidacija, numerična analiza
Published in DKUM: 22.08.2022; Views: 704; Downloads: 60
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