Coursework - Drawing up and calculation of roadway structure (2 variants)

Contents

Task

Introduction

1. Brief description of the area

1.1 Relief

1.2 Climate

1.3 Hydrological conditions

1.4 Physical and geological conditions

2. Constructing Layers of Pavement

2.1 Calculation of permissible elastic deflection of road lining

(Option No. 1)

2.2 Calculation of permissible elastic deflection of road lining

(Option No. 2)

3. Comparison of Road Construction Options

4. Roadway Design Check Calculations

4.1 Calculation of shear resistance in underlying soil

4.2 Calculation of shear resistance in the sand layer of the base

4.3 Calculation of Bending Tensile Resistance

asphalt concrete pavement

5. Calculation of road clothing for frost resistance

6. Consumption of road construction materials for road construction

Conclusion

List of used literature

Introduction

The increasing motorization of the national economy of the country determines the further development and improvement of the road network. Modern road is a complex engineering structure.

Roads are built in a wide variety of natural conditions of the country and the sharp difference in climatic, soil-soil and hydrological characteristics of different areas does not allow the use of screen solutions when designing road elements in plan, longitudinal and transverse profiles.

One of the expensive elements of the road is road clothing. The cost of its construction reaches 60% of the total cost of construction. Subject to the direct impact of traffic loads and natural factors, road garments work in harder conditions than other road structures. Therefore, the purpose of the roadway structure should be carefully considered, combining the desire to ensure:

- structural strength

- reduction of construction cost

- reduction of materials used

- reduction of construction and commissioning time of roadway

- the possibility of using modern construction technologies.

Brief description of the area

The Vologda region was formed on September 23, 1937 and is located in the northern part of European Russia. The regional center is the city of Vologda. The total area of ​ ​ the region is 145,700 square meters. km, which is about 1% of the territory of the Russian Federation. The predominant type of terrain is flat. From North to South, the region stretched for 250385 km, and from West to East for 650 km. The expanses of the Vologda Oblast are wavy, hilly, in some places flat plain, cut by rivers and covered by lakes. The highest height (304 meters above sea level) is located on the Vepsovskaya Upland. Forests occupy 65% of the region, 12% of the swamp, 10% of agricultural land. In the region of 4240 lakes with an area of ​ ​ more than 1 hectare (the largest Onega, White, Kubenskoye) and 1300 rivers with a length of more than 10 km. Of the 13 major rivers, with a total length of about 3,000 km, Sukhona, Sheksna, Mologa, Vologda, Kubena, Suda, Malaya Sev are the most important. Dvina, South. Along the rivers Sukhone and Sev. Dvina has a direct exit to the White Sea, and through the Volga-Baltic waterway system to the Baltic and Caspian.

1.1 Relief.

The Vologda region is located in the northeast of the East European Plain, the relief here is hilly - the lowlands (Prionezhskaya, MolultiSheksninskaya), ridges (Andogskaya, Belozerskaya, Kirillovskaya) and uplands (Andomskaya, Vepsovskaya, Vologda, Galich, Verkhnevazhskaya) alternate. The height of the region above sea level is 150-200 meters. The surface is a low-lying plain with many lakes, swamps, rivers and numerous low ridges and elevations. On the territory of the region, the watershed of Eurasia between the basins of the Arctic, Atlantic oceans and the basin of inland runoff (Caspian Sea). In the southeast of the region - North Uvaly.

1.3 Hydrological conditions

Hydrogeological conditions in the territory under consideration are quite complex.

Surveys have established the presence of aquifers in the strata of Quaternary and Perm sediments.

The groundwater of the Perm horizon lies at a significant depth and is characterized by high mineralization. They have no practical significance for water supply purposes.

Subterranean waters of the Quaternary stratum are ubiquitous and represented by the "headland" and the moraine aquifer. They are fed by infiltration of atmospheric precipitation into the soils, the maximum amount of which falls in spring and autumn, and unloading - into the local erosion network and the Sheksna River.

"Verkhovodka" is confined to alluvial and lake-swamp sediments: sands, sandy loam, peat. It lies almost from the surface.

Groundwater of the moraine horizon is confined to lenses and interlayers of sands, which are quite often found in moraine loams. The isolated nature of the occurrence of lenses and interlayers of watered sands determined the dynamics of groundwater. Watered sands are found at various depths, almost throughout the horizon of moraine loam. Often, groundwater found at small depths of 2-5 m has a free surface, opened at large depths, can have a local pressure of 110 m. Groundwater nutrition is atmospheric - due to precipitation infiltration, annual fluctuations in groundwater levels depend on the amount of precipitation. The amplitude of their level fluctuation is from 1.4 to 2.7 m.

The total slope of groundwater follows the slope of natural terrain.

In terms of chemical composition, groundwater is mainly of the hydrocarbonate-calcium type with mineralization of 0.20.8 g/l.

Estimated soil filtration coefficients are:

fine-grained and different-grained sands 3.05.0 m/day;

sandy wood - 1.0 m/day;

loam - 0.2 m/day.

1.4 Physical and geological conditions

From physical and geological processes and phenomena in the area of ​ ​ the city, erosion processes associated with the activities of rainwater and meltwater are noted, which led to the formation of ravines and small promontory on the slopes of the moraine plateau and river terraces. Part of the ravines are valleys of streams. They are characterized by a small steepness of the slopes and arrogance. Signs of a landslide are rare.

The most intense erosion activity in the form of coastal erosion is observed in the valley of the river. Serovka near the mouth and along the slopes of its right-bank ravine.

In addition, peat formation, which has little development within the city, should be noted from modern physical and geological processes. The formation of peatlands is facilitated by a large amount of atmospheric precipitation, a small amount of evaporation, flat relief, poor water permeability of soils and high standing of the ground water level.

Soils forming the territory of the city are susceptible to dipping during freezing and subsidence during thawing. According to the degree of frosty puffiness, loam and sandy loam belong to highly pristine soils, dusty sands to medium-pristine ones. The foundations of buildings, underground devices and pavements located in the zone of seasonal freezing of soils systematically experience the effect of beam forces at negative temperatures. Light structures with shallow recessed foundations are particularly affected.

When pits open water-saturated sand lenses, suffosion phenomena are possible - the removal of sands from the walls of the pit and their fusing.

Roadway Design Check Calculations

Due to the complexity of the processes occurring in deformable road clothing, when calculating its main strength index, a complex characteristic is taken - permissible elastic deflection. The roadway design meeting this requirement shall also be checked according to the following criteria:

- stability of unrelated layers against shear;

- permissible value of tensile stresses in layers of bonded materials;

- permissible value of winter swelling;

- provision of water discharge from porous layers.

Conclusion

In this work, 2 types of roadway structures were considered. By sequentially calculating and comparing the options, the optimal type of road clothing was chosen.

The selected type of pavement provides:

- structural strength;

- lower construction costs;

- less demand for the amount of material used;

- faster construction and commissioning.

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