Case Study on Safety Assessment of Rockfall and Splash Stone Protective Structures for Secondary Excavation of Highway Slope

Rockfall occurs on the excavation of the slope of highway resulting from excavated rock pieces. In order to solve the problem of rockfall protection during the disturbance of high slope secondary excavation, rockfall analysis program RocFall was used to perform inverse calculation for rockfall path of excavation disturbed rock. Based on a case study of a reconstruction and expansion project, two rockfall movement models were proposed under excavation disturbance. Moreover, the safety of protective structures under five protection schemes and different initial rockfall movement points is evaluated according to the rockfall interceptions rate. The evaluation results were further verified by long-term field observation. The results show that the protective structure at the slope top has a better interception effect to rockfall. It was difficult to intercept the splash stone, which threats to the traffic safety of the existing roads. According to different construction points of mechanical excavation and the interception rate of splash stone by the protective structure, the forbidden region and safety region of mechanical excavation were proposed.

Methods for reducing the environmental impact of rock mass excavation

Many engineering projects and interventions have negative effects on the environment. Rock excavation in civil engineering, either in mining or in construction, often is unthinkable without the use of explosive. However, blasting can have extensive adverse environmental impacts, like vibrations, noise, dust and chemical contamination. Therefore, it is better to avoid blasting activities near urban areas, protected animal habitats, sensitive historic buildings, water protection zones, pipelines, etc. While mechanical excavation is often longer lasting and more expensive, in some cases it may adequately replace blasting, where the applicability of mechanical excavation methods greatly dependent on the rock mass characteristics which should excavate. This paper provides practical examples of using existing methods for the assessment of the applicability of excavation technologies. In order to minimize the project impact on the environment, mechanical excavation was applied in some cases. In one case, the blasting could not be avoided, but controlled careful blasting techniques were applied.

Mechanisation of Longwall Extraction of Hard and Abrasive Rocks

The article presents the current topic of the possibility of mechanical extraction of hard and abrasive rocks using mechanized wall systems. The problem of extracting ores from thin strata precludes the possibility of further use of current technologies involving a human at the face. Currently, the operation is carried out using explosives in column-pillar systems. In systems with a chamber column, all major processes are mechanized and carried out by self-propelled drilling and bolting machines, loaders as well as hauling and auxiliary trucks. These machines are operated in the workplace by operators. For many years, effective mechanical excavation methods were sought that would allow the development of a mining machine and a mechanised longwall complex. Such a complex is to allow excavation without the presence of humans at the face. The article presents the current technical capabilities, assumptions and requirements for such a solution. Then, an innovative longwall complex equipped with a disc shearer is introduced. The technology of work and achievable productivity are briefly presented. A worn shearer, a face conveyor and a powered support are the subject of AGH inventions.