From birth to long-term life—main aspects regarding THM-coupled simulation of salt cavern behavior as well as regarding improved salt cavern design with special consideration of rock salt damage

2015 ◽  
pp. 285-302 ◽  
Keyword(s):  
Rock Salt ◽  
Special Consideration ◽  
Coupled Simulation ◽  
Salt Cavern ◽  
Salt Damage

Rock Long-Term Strength Parameters Determination of a Salt Cavern Gas Storage

2013 ◽  
Vol 353-356 ◽  
pp. 1685-1688
Author(s):  
Li Na Ran ◽  
Hua Bin Zhang ◽  
Zhi Yin Wang
Keyword(s):  
Mechanical Properties ◽  
Rock Salt ◽  
Gas Storage ◽  
Surrounding Rock ◽  
Creep Process ◽  
Term Strength ◽  
Salt Cavern ◽  
Study Results ◽  
Salt Cavern Gas Storage

In order to determine the long-term mechanical properties of surrounding rock of salt cavern gas storage, long tri-axial creep test studies on rock salt of the field were carried out. Based on the test data, long-term strength of rock salt was determined, and comparatively analysis was conducted combined with of the instantaneous test. The study results show that: Considering the axial strain, radial strain and volumetric strain to determine the long-term strength of rock salt can ensure reliability of the results. Under the same condition, the less salt content, the value of long-term strength is higher. Tri-axial creep process has a different effect degree between cohesion and internal friction angle; it is more sensitive to cohesion. The strain limit should be considered for the stability analysis of multi-bedded salt cavern gas storage construction and pay more attention about the mechanical properties of the interlayer parts. The study results provide references for researching the surrounding rock long-term mechanical properties of salt cavern gas storage.

scholarly journals Probabilistic Analysis of a Rock Salt Cavern with Application to Energy Storage Systems

2016 ◽  
Vol 50 (1) ◽  
pp. 139-157 ◽  
Author(s):  
Elham Mahmoudi ◽  
Kavan Khaledi ◽  
Shorash Miro ◽  
Diethard König ◽  
Tom Schanz
Keyword(s):  
Energy Storage ◽  
Rock Salt ◽  
Probabilistic Analysis ◽  
Storage Systems ◽  
Energy Storage Systems ◽  
Salt Cavern ◽  
Rock Salt Cavern

The analysis of dates obtained from long-term creep tests to determine creep coefficients of rock salt

2018 ◽  
Vol 78 (3) ◽  
pp. 1617-1629 ◽  
Author(s):  
Mohammad Bagher Eslami Andargoli ◽  
Kurosh Shahriar ◽  
Ahmad Ramezanzadeh ◽  
Kamran Goshtasbi
Keyword(s):  
Rock Salt ◽  
Creep Tests ◽  
Term Creep

Accelerated long-term forgetting in focal epilepsies with special consideration given to patients with diagnosed and suspected limbic encephalitis

Cortex ◽  
2019 ◽  
Vol 110 ◽  
pp. 58-68 ◽  
Author(s):  
Christoph Helmstaedter ◽  
Babette Winter ◽  
Nico Melzer ◽  
Hubertus Lohmann ◽  
Juri-Alexander Witt
Keyword(s):  
Limbic Encephalitis ◽  
Special Consideration

scholarly journals The Influence of Operation Pressure on the Long-Term Stability of Salt-Cavern Gas Storage

2014 ◽  
Vol 6 ◽  
pp. 537679 ◽  
Author(s):  
Jianjun Liu ◽  
Qiang Xiao
Keyword(s):  
Internal Pressure ◽  
Element Model ◽  
Gas Storage ◽  
Salt Cavern ◽  
Term Stability ◽  
Long Term Stability ◽  
Rock Creep ◽  
Operation Pressure ◽  
Salt Cavern Gas Storage

The operation pressure of underground salt-cavern gas storage directly affects its stability. Because of seasonal demand and other emergency reasons, the gas storage working pressures always change from high to low or from low to high cyclic variation. In order to analyze the effect of gas storage pressure changing on its long-term stability, considering the salt rock creep, a 3D finite element model was built using the software Abaqus. Moreover, the deformation and analyzed results of the storage under 0 MPa, 4 MPa, 6 MPa, 8 MPa, 10 MPa, and 12 MPa and also circulating changes pressure operation were given in the 10-year creep. It concluded that how working pressures have effect on long-term stability of salt-cavern gas storage. The research results indicated that the long-term creep performance of underground salt cavern gas storage is affected by internal pressure, the smaller the internal pressure creep is, the more obvious the creep and the greater deformation of gas storage are. The greater the internal pressure is, the smaller the deformation of the gas storage is. The low pressure and excessive high pressure must be avoided during the operation of gas storage. These results have an important significance on determining the reasonable pressure of gas storage operation and ensure the long-term stability of gas storage.

scholarly journals Over 30 years of research on crushed salt as a barrier material: fundamental findings and open questions

2021 ◽  
Vol 1 ◽  
pp. 137-139
Author(s):  
Kornelia Zemke ◽  
Kristoff Svensson ◽  
Ben Laurich ◽  
Johanna Lippmann-Pipke
Keyword(s):  
Radioactive Waste ◽  
Rock Salt ◽  
Radioactive Waste Disposal ◽  
Test Series ◽  
Triaxial Tests ◽  
Barrier Material ◽  
Environmental Controls ◽  
History Of

Abstract. Repositories for high-level radioactive waste in geological formations require knowledge on thermal, mechanical and fluid transport properties of the whole repository system, including the engineered barriers and backfill materials. For about 30 years, crushed salt has been considered the most suitable geotechnical barrier material to backfill cavities and encapsulate radioactive waste in rock salt repository sites (e.g., Czaikowski et al., 2020). Over time, when the surrounding cavity walls converge by the creep of salt, it can become strongly compacted and safely encapsulates radioactive waste from any fluid flow. Hence, crushed salt has been characterized in detail for its physical material properties and its response to environmental controls (stress, temperature and moisture). This characterisation provides a basis for long-term numerical simulations (e.g., Liu et al., 2018), which verify so-called safety cases in radioactive waste disposal. Displacement-controlled oedometric compaction tests mimic the long-term in situ behaviour of crushed salt. The tests show that it can be compacted to a state comprising physical rock properties similar to natural rock salt. In general, compaction is easier with an increase in humidity and temperature (e.g., Stührenberg, 2007; Kröhn, et al., 2017). Triaxial test series address the compactions' response to differing confining pressures and help to identify generalized constitutive equations for crushed salt. Both BGR procedures, the oedometric and the triaxial compaction, are verified by the German accreditation body (DAkkS). Figure 1 illustrates the history of oedometric tests at the BGR laboratory since 1993, which examined crushed salt from various origins and differing temperature conditions. Most tests focused on material from the Asse mine, revealing the compactions' response to the materials' humidity and to brine flow. Moreover, systematic test series with synthetic grain size distributions and bentonite additives provided a basis for barrier material design. More recent tests on bedded salt formations (e.g., Teutschenthal and Sondershausen mines) allow the differentiation from characteristics from domal salt deposits (e.g. Gorleben). The current research continues the history of oedometric and triaxial tests, but has a new focus on late compaction stages with marginal remaining porosities (<5 %). The approach of systematic material characterization under best-controlled conditions essentially benefits from the international research collaboration in the KOMPASS project (Czaikowski et al., 2020). The aim of its current phase two is to synthetically generate, identify and quantify dominant grain-scale deformation processes in response to changes in environmental controls. Subsequently, these laboratory results will be embedded in numerical models on the long-term in situ rheology of crushed salt.

scholarly journals Pilot plant tests to demonstrate the functionality of sealing elements made of salt cut bricks

2021 ◽  
Vol 1 ◽  
pp. 117-119
Author(s):  
Uwe Düsterloh ◽  
Svetlana Lerche ◽  
Juan Zhao
Keyword(s):  
Rock Mass ◽  
Rock Salt ◽  
Salt Solution ◽  
Pilot Plant ◽  
Research Work ◽  
Surrounding Rock ◽  
Bonding System ◽  
Joint Volume ◽  
Sealing Elements

Abstract. The long-term safe containment of high-level radioactive waste in a repository in rock salt is ensured if the geological barriers in conjunction with the geotechnical barriers are permanently impermeable to fluids. As such, an essential factor in underground disposal is to confirm that the interfaces between the biosphere and the lithosphere, i.e., shafts, boreholes, and galleries, created during the excavation of underground cavities can be sufficiently tightly sealed. An essential element of the sealing system required to this end is shaft closure. All shaft closure concepts developed thus far include sealing and supporting elements in repository shafts, but differ in the arrangement of these structural elements and the materials used. The materials currently proposed and planned for the construction of the sealing elements include: clay/bentonite, asphalt/bitumen, crushed salt, and salt/sorel cement. In addition to the materials mentioned above, a research project funded by the German Federal Ministry for Economic Affairs and Energy (Bundesministerium für Wirtschaft und Energie, BMWi) is investigating the possibility of integrating a layer of salt cut bricks several decameters to 100 m thick into the shaft closure system as a sealing element that provides the option of allowing the geological barrier to heal in the long term. Like the surrounding rock mass, the salt cut bricks are made of natural rock salt. According to this plan, the profile of the bricks is designed to minimize joint volume as far as possible by cutting them to match the geometry of the shaft. The joints between the salt cut bricks can either be filled with, for example, a supersaturated salt solution, Magnesium building materials, molten salt, crushed salt, etc., or directly brought into contact by wetting the surface of the salt cut bricks. Once the salt solution has hardened (cooling of the solution, evaporation of the mixing water), only the pore space in the crushed-salt joint sealant filled with salt solution or air, or the joint volume resulting from the mismatch between individual rock salt bricks are susceptible to a reaction. This means that the sealing element consisting of salt cut bricks develops early supporting pressure against the creeping rock salt of the rock mass compared to crushed salt, has a low initial porosity and already shows a strong sealing effect in the short term (regression of the loosened zone). One can also assume that cohesive bonding between the surrounding rock and the sealing element can already be achieved by introducing the joint filling or by wetting the contact surfaces of the salt cut bricks (no or reduced separation planes in the contact zone). Essential prerequisites for the investigation of the geomechanical-geohydraulic effectiveness of a sealing element made of salt cut bricks included the development and construction of a pilot plant to analyze the mechanical and hydraulic material properties of the bonding system comprising salt cut bricks and joint sealing (FKZ 02E11223, FKZ 02E11425), as well as preliminary investigations on the production of salt cut bricks and joint sealant (→ cutting technique/processing of salt cut bricks; maufacture/workability of jointing material) and on the spatial arrangement of the salt cut bricks (→ avoidance of continuous axial joints in the bonding system, Fig. 1). The presentation includes the results of the research work on the development, construction and commissioning of the pilot plant, as well as the first successful test results demonstrating the functionality of sealing elements made of salt cut bricks.

Sign in / Sign up

Export Citation Format

Share Document