Developing the structural and technological solutions for repair and restoration of sewer collector using clinker brick.
Thesis in support of candidature for the degree of Doctor of Philosophy in specialty "192 - Construction and Civil Engineering" - Kharkiv National University of Civil Engineering and Architecture, Ministry of Education and Science of Ukraine, Kharkiv, 2021.
Taking into account that a significant part of them passes through areas where there are not any feeder roads, through agricultural lands and has a small depth, as well as the fact that, as a rule, their flume parts in a condition suitable for further operation, it is efficient to restore them by open cut trenching method.
The thesis promotes the idea of restoring the vault part using the remaining flume parts of the collectors for erecting a structure made with the use of clinker bricks, which is connected with the structures of the existing flume. In this process the vault part is constructed by means of a pneumatic shuttering.
During work performance the remaining flume parts of the collectors was used where a reinforced ribbed polyethylene pipe was placed. After that, clamps and ready made forms were installed and concrete was poured to build a new vault. At the same time, a significant number of technological operations were performed at a factory. The open cut trenching method for repair and restoration of the sewer involved using pipes lined with slag casting, polyethylene and fiberglass pipes, which are placed in the remaining flume elements which reduces the capacity of the rebuilt collector.
Theoretical verification of the proposed design solutions for transformation and rehabilitation of collectors is performed by 3D-finite-element modeling of the bi element called "component shell of the collector - plot of soil with predetermined properties." In this case, the assessment of its performance during the a priori defined life cycle is performed by using a new energy criterion of the limit state, which is formulated for materials that differently resist compression, tension and shear strains.
An important part in implementation of the proposed technology is use of pneumatic shuttering.
To investigate pneumatic shuttering materials production samples used in Kharkiv region where similar products are manufactured, were selected.
The thesis describes experimental research whose purpose was to choose a brick sample in terms of its use for repair and restoration of sewer collectors by the open cut trenching method. For the research, the analysis of the clinker brick market of Ukraine was carried out and 18 samples were selected, including 11 domestic samples and 7 foreign analogues.
The resistance of the brick samples to aggressive environment was tested by keeping them for 90 days in a biochamber in the form of an inspection shaft of a deep sewer tunnel where the concentration of hydrogen sulfide and other chemical compounds several times exceeded the maximum concentration allowed by the state regulations.
When keeping the samples in the aggressive environment, intermediate values of concentration of the substances were determined.
At the end of the tests, brick samples were selected and they were recommended for prospective use for repair and restoration of sewage collectors.
At the laboratory of the Department of Building Materials the experiments on proportioning of mortar were conducted for its prospective use for repair and restoration.
Besides the core ingredients of the mix of the mortar it was recommended to add expanded clay powder as a mineral additive and aggregate in the amount of 20% by weight of cement and chemically active additive ХАД 7 in the amount of 7 -12% by weight of cement.
The cubes made of such mortar were tested in an aggressive environment being kept in one of the inspection shafts where the concentration of hydrogen sulfide was several times higher than the maximum allowable. The tests showed positive results.
To confirm efficiency of the open cut trenching method for repair and restoration of sewage collectors using clinker brick, the thesis considers two options for restoration of the collector: using clinker brick and replacement of ruined collectors with new polyethylene or fiberglass pipes.
The economic calculation of restoration options showed that the use of clinker brick costs almost 4 times less compared to the cost of work using polyethylene pipes.
