Ralf-Michael Günther

• Dr.Ing.
• Managing Director at Institut für Gebirgsmechanik, Leipzig

Salt caverns are utilized for the underground storage of hydrocarbons due to the essentially impermeable nature of salt under appropriate pressure conditions. Con-sequently, designing and operating these caverns safely and economically necessi-tates a thorough understanding of the hydromechanical behavior of rock salt. This paper examines fluid tra...

The Asse II mine is an over 100 years old salt mine in a steep inclining structure of a salt ridge in which radioactive waste was embedded from 1967 to 1978. Due to instability in a long-term sense, fracturing in the pillars and overhand stopes took place and a brine inflow has been observed since 1988. Considering the Atomic Energy Act (Lex Asse)...

The search for a site of a final repository for highly radioactive waste in Germany was renewed when the Site Selection Act (StandAG) came into force in 2013. In Germany the development of concepts for a final repository and safety analyses for a repository in a salt dome was prioritized for many decades, whereas repository concepts in clay and cry...

WEIMOS is the fourth in a series of joint projects related to constitutive modelling of rock salt. The general aim is to test, improve and validate the advanced constitutive models developed by the partner institutions, with the goal of providing suitable tools to assess the long-term safety of waste repositories in salt formations. WEIMOS focuses...

In a joint project series on the comparison of constitutive models between 2004 and 2016, the physical description of various thermo-mechanical deformation phenomena in rock salt was studied with many systematic laboratory tests, back-calculations of the tests, and simulations of selected real in-situ situations. One aim of the third project (2010-...

Creep at small deviatoric stresses and damage reduction (healing) of rock salt are two of the four physical phenomena being studied in the joint project WEIMOS, as part of lab testing. Creep at small deviatoric stresses affects the closure rate of repository rooms to isolate the waste. Damage reduction behavior, on the other hand, controls the time...

Actual problems in geotechnical design, e.g., of underground openings for radioactive waste repositories or high-pressure gas storages, require sophisticated constitutive models and consistent parameters for rock salt that facilitate reliable prognosis of stress-dependent deformation and associated damage. Predictions have to comprise the active mi...

The Asse II mine is an over 100 years old salt mine in a steep inclining structure in a salt ridge in which radioactive waste was embedded from 1967 to 1978. The mining chambers were excavated leaving pillars and stopes stable only in a short-term sense. Because the upper chambers at the southern flank are located very close to the neighboring over...

Despite significant progress in the salt mechanics, particularly regarding understanding of the most important deformation and damage mechanisms, the importance of tensile failures is still largely underestimated. The time-dependent development of the “Excavation Damage Zone” (EDZ) as well as the formation of instabilities cannot be properly explai...

Under high deviatoric stresses, rock salt shows shear failure, which is accompanied by microdamage. Microscopically , damage results from the accumulation of microcracks, leading to mechanical softening, increased permeability and a volume increase, known as dilatancy, which is a convenient damage indicator since it is directly accessible in the la...

Actual problems in geotechnical design, e.g. of underground openings for radioactive waste repositories or high- pressure gas storages, require sophisticated constitutive models and consistent parameters for rock salt that facilitate reliable prognosis of stress-dependent deformation and associated damage from the initial excavation to long times....

Actual problems in geotechnical design, e.g. of underground openings for radioactive waste repositories or high- pressure gas storages, require sophisticated constitutive models and consistent parameters for rock salt that facilitate reliable prognosis of stress-dependent deformation and associated damage from the initial excavation to long times....

Since 2004, three Joint Projects on the Comparison of Constitutive Models for the Thermo-Mechanical Behavior of Rock Salt have been performed. The general objectives are to document, check, and compare the advanced models and modeling procedures, to validate their suitability for numerical simulations and reliability, to increase confidence in the...

In numerical simulations for the design and stability analysis of underground openings in rock salt, the geomechanical behavior of the host rock is described with constitutive models. In recent decades, various advanced models and procedures for the determination of salt type-specific parameter values and for the performance of numerical simulation...

A powerful constitutive model is presented which describes the complex mechanical behavior of rock salt in a good approximation. The model contains a state variable to characterize the effective material hardening which is growing with ongoing creeping. However, hardening is reduced again by recovery and damage. The viscosity of the creep model dep...

A powerful constitutive model is presented which describes the complex mechanical behavior of rock salt in a good approximation. The model contains a state variable to characterize the effective material hardening which is growing with ongoing creeping. However, hardening is reduced again by recovery and damage. The viscosity of the creep model dep...

In the scope of a unified approach to describe the creep behavior the constitutive model as presented here describes comprehensively the mechanical behavior of rock salt in a good approximation. In this model, hardening is used as an inner variable of state. This model has been verified by the results which were obtained when recalculating differen...

For stability analyses as well as for predictions of the future geomechanical behaviour of underground openings in salt rock strata, proper calculation tools are needed. Numerical calculation methods and material laws are required to describe the mechanical behaviour of salt. A proposed new material salt creep law describes the deformation-hardenin...

Gegenstand der Dissertation ist die Entwicklung eines Stoffmodells für duktile Salzgesteine, mit dem alle drei Kriechphasen, abhängig von einem inneren Zustandsparameter, beschrieben werden können. Die Modellierung der Schädigungs- bzw. Dilatanzentwicklung und deren Rückkopplung auf das Kriechverhalten ist das Kernstück der Stoffmodellentwicklung....