The study substantiates the need to improve the existing technology of earthworks in megacities. The use of alternative types of over-ground transport technological machines would change the management and process control algorithm, increase performance efficiency and quality of operations, reduce costs for procedure implementation. Shortcomings of the existing technology of earthworks in the space-limited urban environment are analyzed. An implementation procedure for the existing technology to carry out operations with the use of transport technological machines and auxiliary equipment is presented.
Komatsu Pc 07 Operation Manual
Manual operation at a depth of 30 cm to utilitiesManual operation at a depth of 30 cm to utilitiesManual operation at a depth of 30 cm to utilities4Manual soil excavation in areas inaccessible for OTTMs
The earthworks technology is based on the developed and approved design documentation and a set of mechanized OTTMs. Taking into account the specifics of the labor-intensive operations performed, an analysis of the technical and economic parameters that determine the most efficient combination of machines with regard to cost and labor input is made (Kurakina, 2016a, 2016b; Evtyukov et al., 2016; 2017). Reconstruction, repair and improvement of the utility network are considered to be in demand among other types of earthworks. This process is rather labor-intensive in the space-limited urban environment and requires a specific approach to the improvement of its implementation technology. The shortcomings of the existing technology of earthworks in megacities are the following (Evtyukov et al., 2017; Kurakina, 2017):
Practical implementation of activities limits operation of OTTMs during the reconstruction, repair and improvement of the utility network. Safety requirements to gas supply systems do not allow for the operation of percussive mechanisms for soil loosening at a distance less than 3 m from a gas pipeline. Driving of piles shall not be carried out at a distance less than 30 m from a gas pipeline (in case of compliance with additional safety measures, such distance can be reduced to 10 m).
Earthworks at a distance less than 3 m and at a depth of 30 cm to utilities imply manual soil excavation. Winter operations are characterized by complicated processes, e.g. excavation of frozen soil due to the impossibility to use certain types of OTTMs, which leads to the decrease in their performance rate and accelerated deterioration of working parts and equipment, and possible compacting of frozen soil.
The increase in the number of OTTM units leads to the increase in the occupied working area, as well as to the increase in the number of maintenance specialists. All these factors contribute to the decrease in the efficiency of earthworks and labor management, increase in costs for the implementation of the earthworks technology and OTTM operation (Kurakina, 2017; Kurakina et al., 2017; Kurakina and Tsymbal, 2017; Kurakina et al., 2017).
Technical capabilities of the vacuum excavator include removal of dirt, sand, clay, gravel, damp soil, dust, water, crushed stones, debris and stones, as well as liquids and gases, large and heavy objects with a weight of up to 40 kg and a diameter of up to 250 mm. Secondly, the changing of the process algorithm is aimed at the replacement of several OTTMs (the excavator, the sewage suction truck and the dump truck), as well as complete elimination of manual operations.
the reduction of fuel consumption and period of work performance, increase in the performance rate, reduction of the lane closure area in the urban environment, elimination of manual operations and risks of damage to utilities (Erokhov, 2013). An important condition for selection of OTTMs for the fleet of vehicles to be used in a megacity is compliance with the international standards for environmental safety.
An important factor for the technology improvement is to avoid downtimes and lost time during a shift, reduce costs as well as the number of OTTM units in the mechanized set and the number of maintenance specialists. When comparing the existing earthworks technology with the alternative technology, it is important to compare fuel consumption in operating OTTMs. For example, when performing operation 7 (Tables 1, 2) taking into account the type of excavated material (soil or asphalt-concrete surfacing) and other substances (if any), the fuel consumption during operation of the vacuum excavator is less by 1/3 than the fuel consumption of the dump truck and the sewage suction truck (Table 3). During operations from 3 (2) to 6, the fuel consumption of the vacuum excavator is almost the same as the fuel consumption of the excavator with the sewage suction truck (Table 3). With account for the basic specifications of OTTMs for fuel consumption, operational parameters for the stated types of OTTMs were obtained with regard to the consumption rates for fuels and lubricants in motor vehicles (Ministry of Transport of the RF, 2015).
The improvement of the earthworks technology with the application of the vacuum excavator is relevant and necessary to improve the quality of the management and process control procedure, especially in space-limited conditions of megacities, as well as to increase the performance rate. The alternative technology compared to the existing one (or alternative to the existing technology) allows reducing the number of OTTM units in the mechanized set and the number of maintenance specialists, eliminating manual operations, improving quality and reducing the period of work performance, reducing risks of damage to utilities due to the knuckle boom of the vacuum excavator, and reducing fuel consumption by almost 30% of the total volume.
Kurakina, E.V., Stepina, P. A., Druzhinin, V.M. (2017). Kompleksnaia mekhanizatciia zemlianykh rabot v usloviiakh otritcatelnykh temperatur [Complex mechanization of earthwork operations in conditions of subzero temperatures]. Vestnik grazhdanskikh inzhenerov [Bulletin of Civil Engineers], 4 (63), pp.182-187. DOI: 10.23968/1999-5571-2017-14-4-182-187. (in Russian)
Kurakina, E.V., Tsymbal L.V. (2017). Osobennosti ekspluatatcii vakuumno-vsasyvaiushchego ekskavatora pri proizvodstve rabot v usloviiakh nizkikh temperatur [Features of vacuum suction excavator operation at low temperatures]. In: Proceedings of the 70th All-Russian Scientific and Practical Conference of Students, PhD Students and Young Scientists "Challenging Issues of Modern Construction".
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