Assessment of soil compacted state in forest road costruction

The issue of soil compacted state forecasting during the construction of a forest road is considered. The mechanical system formation of contacting particles of the compacted soil are given and substantiated. A model of compaction of a loose soil layer in the system "compaction device - compacted material" has been developed. A new compartment approach in this field of applied research was used, within which the system under study is subdivided into interconnected units, called compartments, the content of a certain substance in each of them is a separate variable of the system. Various technological situations are analyzed with the minimum and maximum allowable boom outreach of the excavator. The modeling of the effect of porosity on the soil layer thickness during its compaction, denser packing of particles and the appearance of residual (irreversible) deformations has been carried out. A method for determining the relationship between the degree of soil compaction and changes in its porosity and deformations has been developed. The complexity of the theoretical study of the compacted soil is substantiated. The practical significance of the developed model of soil layer compaction and the methodology for assessing its deformations has been confirmed with successful implementation at the design and monitoring stages of the construction of a pilot section of a forest road located in the Republic of Karelia on the basis of Petrozavodsk State University.

Recycled Polyester Geosynthetic Influence on Improvement of Road and Railway Subgrade Bearing Capacity— Laboratory Investigations

After years of using geosynthetics in civil engineering and infrastructure construction, it has recently become necessary to consider the possibility of recycling and reusing these materials. This paper presents the results of laboratory tests of the effect of recycled geogrid on the bearing capacity of soils using a CBR test. A polyester geosynthetic was selected for testing due to its high resistance to biodegradation and wide application. In a series of laboratory tests, two types of road and railway subgrade were used, mixed with geosynthetic cuttings in two different weight concentrations. The aim of the research was to demonstrate whether old demolition geosynthetics could be used to strengthen road and rail subgrade as recycled material. The influence of the geosynthetic cutting shape was also considered. The obtained results confirm the possibility of using recycled geogrid to improve the bearing capacity of the pavement subgrade, at least under these laboratory conditions. In the case of sand, the use of 2.0% additive causes that the poorly compacted soil obtains sufficient bearing capacity for the layer of road improved subgrade. As expected, the level of this improvement depends on the type of soil and the shape of geogrid cuttings.

The Results of Experiments the Width of the Soil Deeper Like Crushing Angle and Its Impact on Studying Performance

This article presents the results of experiments on the improvement of the plow, equipped with compacted soil plows in the main tillage, in particular, the loosening of the subsoil with plowing, and the effect of the crushing angle of the soil compactor on its performance.

Towers on the Earthen Foundation: New Insights by the Excavation and Boring Survey at the Bayon Temple

Bayon temple, built in the latter half of the 12th century, is one representative temple of the Angkor monuments. To shed light on the foundation structure of the central towers that stand on the elevated terrace, archaeological excavation and boring tests were conducted. Based on these surveys, a unique foundation structure was revealed under the central towers. It was confirmed that there is no laterite or sandstone support structure directly beneath the upper structure, and that there is only compacted soil at a thickness of approximately 16 m above the natural sedimentary soil. On the other hand, a laterite masonry 6 m thick and 7–9 m wide was confirmed from around the compacted soil. In other words, the heavy load of the central towers is supported by compacted soil that is constrained from the sides by a laterite structure. In addition, the boring surveys provided new insights into the low structural property of the backfilled soil after the past excavation survey below the central tower and the extension process of the elevated terrace supporting the central towers. Delivered information about the foundation structure and material of central towers, including soil property, water table, water contents, and bearing capacity will be valuable for the future structural assessment of this temple.

METHOD OF CALCULATION THE STABILITY OF AN EXCAVATOR EQUIPPED WITH A CONE ROLLER

The construction and method of calculating the stability of a crawler excavator equipped with a new working body (cone roller) are considered. The calculation is made on two working positions (longitudinal and transverse) of the excavator, provided that the excavator must apply the maximum force on the working body at an angle of 90°. The force applied by the excavator boom to the cone roller during the introduction depends on the physical and mechanical properties of the compacted soil. The calculation method differs in that during the compaction of the roadbed, the cone sinks into the ground, and the excavator tends to roll in the direction of the rear track support roller, in contrast to the traditional danger of tipping over the front support roller when working with a bucket.

Study on effect of laboratory roller compaction on unconfined compressive strength of lime treated soils

Expansive soils are problematic due to their swell—shrinkage behavior and low compressive strength. They are modified generally with additives such as lime, fly ash, and various other inorganic and organic materials. Chemical stabilization treatments can improve expansive soil properties for its reuse in geotechnical applications. The present study investigates the properties of two types of subgrade soil treated with Lime and compacted by three different methods in the laboratory. The study is mainly focused to bring out the effect of different methods of compaction on the unconfined compressive strength of Lime treated soils and untreated soils. Laboratory investigation included pH, Atterberg limits, cation exchange capacity (CEC), compaction, unconfined compression strength (UCS), California Bearing Ratio (CBR), Scanning Electron Micrographs (SEM) and EDAX before and after lime treatment. Tests were performed on lime treated soils (2, 4, 6 and 8% of lime). The soil samples for unconfined compressive strength test were prepared by static, dynamic and roller compaction methods in the laboratory. Roller compaction was performed using indigenously fabricated Roller compactor cum Rutting Analyzer (RCRA). The results indicate that dry unit weight and UCS of roller compacted lime treated soil is lower than that of dynamic compacted soil. However, dry unit weight and UCS of lime treated roller compacted soil are closer to that of statically compacted soil. Cation exchange capacity of both soils before and after treatment with lime were examined, CEC reduced with increase in lime content.