Many of the railway highways in the country need to be upgraded and repaired due to the usage to which they are subdued through their continuous exploitation.

One of the most important works that are being executed by the company Hidrotehnica SA Orsova is the “remaking, consolidation and over-raising/ protection of the railway in the Iron Gates I region”.

The works are meant to protect the railway highway Bucharest – Timisoara, in the section between the barrage of the hydro-electrical power plant Iron Gates I and Orsova station. The railway is located next to the variation zone of the water of the accumulation lake in the sector between km. 375 + 400 and 386 + 200. The erosions occurred due to the exploitation conditions of the accumulation lake and to the action of the wages upon the bank of the lake where the railway is located. Also in this region the sides are unstable, both near the supporting walls and in the regions without supporting structures for the bridges’ infrastructure and of the railway viaducts. All these factors jeopardize the safety of the railway transport.

The works that are currently carried on have a definitive character, their purpose being to prevent and to eliminate the danger represented by the erosion. Certain specific technical solutions have been imposed in order to ensure the protection of the sides between the minimum (63.00 cm M. A.) and maximum (69.5 cm M. A.) exploitation quotas for the lake of accumulation. Such solutions differ from one region to another depending upon the structure and the nature of the soil, the degeneration degree, the position, etc.

The works are being carried-on only on the water surface, fact that imposed the construction of unique pieces of equipment, such as:

• floating drilling equipment;
• floating concrete mixers;
• floating laboratory for physical – mechanical tests;
• floating cranes, etc.

Taking into account the specific conditions, the professionals who execute these works have used certain technical solutions that are newness in Romania.

As to this, it is remarkable the construction of the protection screen type I, made by a series of pre-manufactured circular elements of reinforced concrete. They are instated on the bottom of the accumulation lake, within the holes dig with IF 30 Beneta – type modified installations, having a 1,080 mm diameter. The pre-manufactured tubes are filled in with concrete, and on the top they are consolidated with a reinforced concrete beam.

Between the screen resulting thereof and the bank of the lake is added the filling of raw stones extracted from the quarry of stone located on the river Mala.

Another solution that was adopted for the first time is the reinforcement with elements of resistance applied in the areas where the rocky base is lower and the layer of ground is thicker, so that the pre-manufactured circular elements type Pfeiffer of the screen type I cannot be properly inserted in the rocky ground.

The resistance elements are realized through drillings with tools FOREX 1,500, equipped with accessories for drilling in rocky grounds and carried by a floating platform, fitted with two-coupled boats weighting 500 t. The compression of the elements of the screen and their links with the resistance elements is realized through a reinforced concrete beam.

Besides these original solutions, Hidrotehnica Orsova is carrying out works for the protection of the bank of the lake by using 5 tons pillars, 2 tons concrete blocks and raw stone that are fitted by divers.

The execution of the bank protection works has been finalized for a surface of 5.2 km. There has left a section of 5.6 km that might be finalized in the next five years, in case the necessary funds are being allocated.

For the valorization of the materials recovered from the write-off of the rail, basically reinforced concrete sleepers, there has been found the solution of using them for the fillings behind the columns through the partial replacement of the raw stone.

From the total value of the works carried out by SC Hidrotehnica Orsova that employs 140 permanent workers (locksmiths, electricians, plumbers, carpenters, welders, mechanics but also miners and sailors), 95% are realized for the National Railway Company CFR SA. This company is specialized in consolidations of embankments, hydro-technical constructions, bridges, etc. The works it performed lately are:

• the movement of the commercial harbor Drobeta Turnu Severin;
• the consolidation of the ground in the Cazane – Orsova region;
• the over- raising of the passenger harbor Drobeta Turnu Severin;
• the protection of the bank of the Simian Island;
• the installations for unloading the concrete from the wagons in the harbors Drobeta Turnu Severin and Orsova, etc;
• capital repairs of the bridge on the Filiasi – Orsove section, mainly bank’s protection and remaking of the infrastructure.

Silvia Mitulescu