Poor design solutions and construction work caused an accident on the stretch between Demiivska and Lybidska metro stations . The examination revealed violations in the construction of the tunnel, KCSA said in a statement, UNN reports .
According to the results of the expert study, it has been finally established that the causes of the emergency on the stretch between Demiivska and Lybidska metro stations are poor design solutions and poor construction work during the construction of this section of the tunnel
KCSA noted that experts have established that the causes of the emergency are:
- the tunnel lining is designed to operate at a much lower groundwater level;
- The tunnel lining was constructed with poor quality and in violation of the ring installation tolerances;
- the stiffness of the tunnel is lower than the design due to the use of wall blocks instead of tray blocks (reduced thickness and lack of ribs).
Laboratory studies confirm gross violations during construction in terms of the lack of chemical consolidation of the soils around the tunnel, which also caused the emergency
The KCSA also pointed out that law enforcement agencies did not provide any information about such laboratory tests of the said examination.
In addition, they stated that all the necessary maintenance and servicing works were carried out in accordance with the established requirements. It was also noted that the left turnaround tunnel, which was built entirely by the tunnel boring complex, is in good technical condition.
They promised to submit the results of the examination to law enforcement agencies.
The KCSA reminded that distillation tunnels between Demiivska and Lybidska stations of the Obolon-Teremkivska line of the Kyiv subway were put into operation in December 2010.
They said that the construction was carried out in difficult mining and geological conditions and waterlogged soils. During the construction, there were emergencies with the shield penetration stopping and further construction of the tunnel using a non-mechanized method.
Recall
On July 23, the prosecutor's office reportedthat in the case of flooding of the tunnels between Demiivska and Lybidska stations in the Kyiv metro, subway officials were notified of suspicion of official negligence.
The KCSA responded to the suspicions of metro officials over the tunnel flooding, in a statement claiming that “the tunnel structure of this section was poorly constructed during construction” and “the main allegations are allegedly improper maintenance and operation of the tunnel”.
On July 24, the Kyiv City Prosecutor's Office statedthat a number of examinations had been conducted in the case of the flooding of the Kyiv metro tunnels, and one of them showed that the cause of the tunnel's destruction was improper operation, not poor construction.