Mathematical Model of Seismoexplosion in Tunnel Surrounding

The construction of objects of critical infrastructures such as a new roads, utility tunnels, communication networks, underground parks and other structures is associated by the way with generation of vibrations in the vicinity of the underground structures, and not only human lives can be lost but also extensive material damage can be expected due to technological and natural hazards based on vibrations. This paper presents the general governing equations for coupled thermo-hydromechanical process in the tunnel surrounds. Modeling and analysis of laminated composite cylinder applied for the objective analysis of shock wave propagation in the soils and possibilities to estimates of the tunnel structure damage.

Internal Erosion of Earth Structures as a Coupled Hydromechanical Process

The present paper describes a model of internal erosion of earth structures based on rigorous thermodynamic principles and the theory of porous media. The focus is concerned with the initial stage of internal erosion, prior to the formation of macroscopic channels, whenthe continuum approach is applicable. The soil skeleton saturated by a pore fluid is treated as the superposition of 3 continua in interaction ;the pore fluid itself consists of a mixture of water and eroded particles. The erosion kinetics is based on the shear stress developed at the solid-fluid interface. The applicability of the model is illustrated by a finite element simulation. The simulations show how the phenomenon of piping preferentially arises in regions where hydraulic gradients are critical. Effects of mechanical degradations due to internal erosion are demonstrated.

Interaction Swelling Bitumen – Host Formation: Scoping Calculations

ABSTRACTThe Eurobitum bituminised waste product (BWP) from the former EUROCHEMIC reprocessing plant in Mol-Dessel (Belgium) contains a lot of salts, mainly NaNO3 and CaSO4. In contact with pore water in an underground repository, the dehydrated salts in the BWP will rehydrate, resulting in swelling and, possibly, a swelling pressure build-up. A high swelling pressure might impede the integrity and the safety of the repository by creation of preferential pathways for radionuclide migration. In Belgium, the Boom Clay is studied as a reference host formation.The interaction between the swelling BWP and the host formation is a very complicated hydromechanical process. It depends not only on the hydromechanical behaviour of the Boom Clay, but also on that of the BWP. The hydromechanical constitutive law of Eurobitum is not yet established. We have therefore realised scoping calculations to assess the stress redistribution and deformation due to the recompression of the clay around a disposal gallery caused by a swelling pressure. Sensitivity studies have evidenced some important influencing factors.The scoping calculations showed that the swelling pressure exercised to the Boom Clay should be limited to 7 - 8 MPa. Beyond this limit, the Boom Clay host formation will be subject to important deformation, and the risk of preferential paths for radionuclide transport becomes very high. The convergence during the excavation of the disposal galleries is of primary importance for a safe waste disposal system design. Indeed, excess convergence may result in a higher damaged zone before disposal of the bituminised waste.