Risk Assessment in accordance to the Swiss guideline ASTRA 89005
It is in all our interest to reduce the risk and provide a high level of safety to tunnel users. Swiss guidelines ASTRA 19004 and 89005 define a quantitative assessment methodology that describes the role of risk analysis in decision making and the evaluation of measures to achieve a higher safety in tunnels of the national roadway system. This methodology has been implemented in LoRis, an internally developed tool that facilitates the investigation of risk and provides information about cost-effective measures for existing as well as new tunnels.
LoRis is built on a Bayesian network, a probabilistic model, that computes the individual risk and relevant FN curves for fatalities and injuries. The underlying scientific approach takes quantitative information regarding events, and processes consequences using mathematical functions and CFD-simulations. The methodology is applicable to tunnels with a length greater than 300 m, open to the transit of normal, heavy goods and
dangerous goods vehicles.
The tool is in continuous development, following the statistical trend of base rates, ready to employ the newest principles and perspectives of the roadway research community. LoRis 2.0 is an officially validated risk assessment tool in accordance to the Swiss guideline ASTRA 89005.
For further information or inquiries, please contact: firstname.lastname@example.org or email@example.com
Rock Mass Grouting
Since its inception Lombardi Engineering has stood-out through its design and consultant activities in the field of rock mass grouting. Based on works in numerous major hydroelectric projects, together with designers, geotechnical engineers, geologists and field control engineers, it has been possible to develop a better understanding of the grouting process over the years through a combination of laboratory, theoretical and field investigations. In particular, information was gained by laboratory studies on the cohesion (yield strength) and dynamic viscosity of different grout mixes, by theoretical studies on grout flow and penetration, and through field monitoring on grout pressures and absorptions (takes), all of which has led to the elaboration of the grouting intensity number concept: GIN. This concept was first introduced more than 30 years ago by Eng. Lombardi, with the intention of avoiding damage to fissured rock formations, whilst greatly improving the efficiency and effectiveness of grouting operations. One of the intentions of the process is to equalise the radius of flow in fissures of varying widths. The GIN concept is a self-regulating approach of simultaneously controlling both the injection pressure and rate of injection, so as to avoid a combination of high volumes and high-pressure, whilst at the same time setting defined limits on maximum volume and maximum pressure. In general, the GIN concept aims to optimize the grouting process. In particular, it aims 1) to grout only where absolutely necessary, in this way avoiding any waste of grout and 2) to use the highest practicable grouting pressures without causing any damage, in order to enhance the efficiency and success of the grouting operation.
Lombardi has ever since undertaken a lot of research to keep abreast of state of the art techniques and approaches. This continuous acquisition of knowledge has allowed grouting designs using the GIN to be refined and to “challenge” rules of thumb and personal or institutional experiences, often leading to dogmatic beliefs.
One of the key aspects in understanding and planning grouting works is the rheology of the grout mix with respect to the fissure characteristic of the rock mass. In view of its importance, Lombardi has introduced the cohesion concept of the cementitious suspension grout which corresponds to the Bingham yield value. Cohesion has a strong influence on the distance a grout can penetrate and thus limits the extension of the grouted zone. There are cases for which it is desirable to have high grout penetrability calling for low cohesion. Alternatively, there are instances in which it is desired to limit the travel of the grout in the formation thus avoiding, at least to some extent, unnecessarily high grout consumption. In such circumstances, travel can be limited through the increase in cohesion.
For the measurement of this grout cohesion, Lombardi developed a plate cohesiometer, also referred to as P.C.M.
It involves a thin plate of 100 x 100 x 1 mm with rough surfaces on which the grout – provided that it has some cohesion - can stick. Depending on the real injection setting, the plate surface can be structurally adapted by different grooves, streaks and holes in order to simulate the actual field conditions. The test, also specified in the German standard (DIN) for grouting, is recommended for the determination and verification of the proper mix design during the design stage, as well as for the index test to guarantee the constant rheology of the grout mix during grouting works.
The plate can be ordered directly by sending an email to firstname.lastname@example.org or through the Chemgrout company homepage https://www.chemgrout.com/products/accessories/grout-testing-equipment/cohesion-testing-system/