Jaak Daemen

• Civil Mining Engineer
• Professor Emeritus at University of Nevada, Reno

Uniaxial and triaxial compression tests have been performed on prismatic specimens of rock salt under confining pressures (σ3) up to 40 MPa. The specimens contain different bedding plane orientations with respect to the major axis. Results indicate that transverse isotropic effects occur under low confinement where the salt strength is lowest when...

Decreasing the gas pressure is one of the most effective methods to increase the working gas capacity of salt cavern Underground Gas Storages (UGS). In this paper, KING-1 and-2 caverns of Jintan salt cavern UGS, Jiangsu province, China, are studied as an example to investigate their responses under extremely low gas pressure. A 3D geomechanical mod...

This paper formulates an empirical strength criterion for the heterogeneous Antalya tufa rock mass assuming that the heterogeneity effect is represented by the unit weight and the porosity of the tufa rock, which is highly variable from a geomechanical point of view. Unconstrained non-linear regression analyses have been used to identify the streng...

In China, the storage of hydrocarbon energies is extremely insufficient partially due to the lack of storage space, but on the other side the existence of a large number of abandoned salt caverns poses a serious threat to safety and geological environments. Some of these caverns, defined as abandoned caverns under adverse geological conditions (AGC...

A closely spaced caverns design for large-scale underground gas storage (UGS) is proposed, in which four caverns compose one group. The pillar widths between adjacent caverns are 0.7D in the same group and 1.5D between different adjacent groups (D is the maximum diameter of the cavern). Caverns in the same group operate with the same injection–prod...

Uniaxial compression tests, triaxial compression tests, Brazilian disk splitting tests, direct shear tests and triaxial creep tests have been carried out on samples cored from Jintan mining district to determine their mechanical parameters. Based on the formation characteristic and the Sonar survey data of an old cavern, a 3D geomechanical model ha...

Permeability of nonsaline cap rock and interlayers is a key parameter for the assessment of the tightness of gas storage caverns in bedded salt formations. X-Ray Diffraction, permeability tests, Scanning Electron Microscope studies and theoretical analyses have been performed for the mudstone cap rock and interlayers of a potential cavern in a bedd...

The lower reaches of the Yangtze River is one of the most developed regions in China. It is desirable to build compressed air energy storage (CAES) power plants in this area to ensure the safety, stability, and economic operation of the power network. Geotechnical feasibility analysis was carried out for CAES in impure bedded salt formations in Hua...

Uniaxial and triaxial compression tests have been carried out on specimens of rock salt, interlayers, and composite rock salt (containing inclined interlayers). In combination with failure mechanism analysis of the stratified rock structures, the variation and impact factors of bonding stresses between the layers have been investigated, and the fra...

The presence of interfaces has a critical influence on the stability and tightness of underground gas/oil storages. In China, these energy storages are constructed mainly in bedded salt formations and are widely distributed. Therefore, it is necessary to study the sedimentary rhythm and mechanical characteristics of the interfaces between beds. The...

Salt rock is internationally accepted as an ideal medium for energy storage. As an energy storage structure, the safety of hydrocarbon storage caverns in salt rock is related to the national economy and to social public security. Risk analysis is an important method of engineering safety evaluation. In this paper the major risks associated with hyd...

In the absence of long-term instrumental data, the presence of fragile geologic features near active faults can provide physical limits on the level of ground shaking that could potentially have significant implications for seismic hazards. This paper introduces a multidisciplinary investigation that uses unfractured hoodoos in seismically active r...

Rock bolts used for the reinforcement of underground mines, tunnels and nuclear waste repositories are made up of low and medium carbon steels, and high strength low alloy steels. Typical rock bolt systems used for rock reinforcement are mechanically anchored bolts, grout anchored, frictional rock stabilizers and strand anchors. For nuclear waste r...

Three experiments performed on cement borehole seals in granite indicate flow through the seal is slightly lower than flow through the intact rock. The experiments were performed at stress states simulating depths of approximately 350, 700, and 1000 meters.

Several types of carbon and high-strength low-alloy (HSLA) steels are being considered for use in the underground reinforcement of the Yucca Mountain Nuclear Waste Repository. In this study, potentiodynamic polarization under reducing conditions was used to determine the corrosion rates (CRs) and passivity behavior of AISI 4340 steel using differen...

Salt rocks are commonly used as geologic host rocks for storage of gas and crude oil, and are being considered for the disposal of radioactive waste. Different from the salt rock domes in many countries, the salt rock formations in China are usually laminar with many alternating layers, i.e. rock salt, anhydrite, and/or mudstone. Considering the un...

Friction type steel rock bolts are one of the most commonly used for reinforcing tunnels (since the late 1970s) due to their ability to sustain large rock mass displacements. In this paper, corrosion behavior of an FRS rock bolt (ASTM A607 steel) was investigated under Yucca Mountain simulated concentrated water at different concentrations (1×, 10×...

High strength low alloy (HSLA) steels are candidate Rockbolt materials for use as underground roof supports at Yucca Mountain nuclear waste repository. Oxidation kinetics of International Rollforms Split Set Friction Rock Stabilizers (SS46), and Swellex Mn24 steels have been determined by temperature modulated thermogravimetry at temperatures rangi...

The electrochemical hydrogen permeation method was used to investigate hydrogen transport, trapping characteristics of low (0.08 pct C) and medium carbon (0.44 pct C) steels proposed for the Yucca Mountain (YM) repository environment. The presence of relatively high amounts of C, Mn, and S increased the density of trapping sites in medium carbon st...

Friction type rock stabilizers have been widely used as a rock reinforcement material for underground support due to its ability to sustain large rock mass displacements. Slotted and tapered steel tube rock bolt is one of the most commonly used materials for these purposes since late 1970’s. It is a slotted steel tube with one end tapered for easy...

Friction rock stabilizers (FRS), such as Swellex* rock bolts are being considered as reinforcement material for the Yucca Mountain Nuclear Repository. Generally, expanded rock bolts are used for rock support in mining and tunneling applications due to various advantages. Expanded Mn24 rock bolts used for rock reinforcement in underground constructi...

High temperature oxidation behavior of High Strength Low Alloy (HSLA) steels that are candidate Rockbolt materials for use as underground roof supports at Yucca Mountain nuclear waste repository have been determined. The oxidation kinetics of Friction Rock Stabilizers SS46, and Mn24 steels have been determined by temperature modulated thermogravime...

Alloy 22 (Ni-22Cr-13Mo-3Fe-3W) is a candidate alloy for nuclear materials storage containers in the Yucca Mountain High Level Nuclear Waste Repository as well as for sub-surface applications. In this study, we present the results of our investigation on the corrosion behavior of Alloy 22 as a function of temperature simulated Yucca Mountain (YM) wa...

This paper presents results of five creep tests conducted in uniaxial compression at room temperature. The test specimens were from the welded Topopah Spring tuff formation at Yucca Mountain, Nevada. The specimens exhibited brittle failure. Multiple stress levels were applied in steps to each specimen. Each stress level was maintained for 3 days or...

Results of 61 uniaxial compression tests on the welded Topopah Spring tuff are presented. The tests were carried out under constant strain rates at room temperature. Stress–strain analysis indicates that dilatancy and compaction start at about 50% of ultimate strength. A sudden stress drop occurs at about 90% of the ultimate strength, which indicat...

Twenty seven triaxial compression tests have been conducted on welded tuff at constant and controlled axial piston displacement rates. The piston displacement rates were then converted to axial stress rates according to a nearly linear load- displacement relation. Specimens were tested in three orders of displacement rates or stress rates and at th...

Friction rock stabilizers (FRS), such as Swellex rock bolts are being considered as reinforcement material for the Yucca Mountain Nuclear Repository. Generally, expanded rock bolts are used for rock support in mining and tunneling applications due to various advantages. Expanded Mn24 rock bolts used for rock reinforcement in underground constructio...

The study of the long term mechanical behavior of Yucca Mountain tuffs is important for several reasons. Long term stability of excavations will affect accessibility (e.g. for inspection purposes), and retrievability. Long term instabilities may induce loading of drip shields and/or emplaced waste, thus affecting drip shield and/or waste package co...

An expansive cementitious borehole plug emplaced in an underground opening in the vicinity of an underground nuclear waste repository may generate radial stresses on the walls of the opening due to an axial stress applied to the borehole plug and due to plug swelling. As these radial stresses may lead to the tensile fracturing of the rock, minimizi...

About a hundred cylindrical welded Topopah Spring tuff specimens from the Yucca Mountain site have been tested in uniaxial compression. Sixty five are selected for a study of strain rate dependence. The following facts are found: 1) ultimate strength, ultimate axial strain and secant modulus evaluated at ultimate strength decrease with a decrease i...

The strength of expansive cement grout borehole plugs cast in rock cylinders is investigated theoretically and experimentally as a function of curing and testing temperature of the plugged rock cylinder and of borehole size. The distributions of thermally induced stresses and displacements, shear stresses along the plug-rock interface due to an axi...

The strength measures of expansive cement grout borehole plugs cast in welded tuff cylinders is investigated as a function of the degree of saturation of the plugged rock cylinder and of borehole size. Details on experimental procedure regarding rock cylinder and cement grout preparation, sample curing conditions, experimental apparatus, sample loa...

The confining pressure and axial pressure effects on the time-dependent stress–strain behavior of salt rock are analyzed quantitatively based on a number of uniaxial and triaxial creep test results in this paper. An exponential function is suggested to model the creep strain from transient to steady-state and found fitting well the creep strain. Th...

We analyze analytically and numerically the stress distribution along the plug-rock interface and within an axially loaded plug emplaced in a borehole in rock. Experiments show that the interface strength increases with decreasing plug radius and with increasing plug length. Axial strength decreases as a power law of plug radius. An increase in the...

This paper examines the bond strength of cement grout plugs cast in rock. The bond strength has been determined through push-out testing in which an axial load is applied to cement grout plugs emplaced in boreholes in welded tuff cylinders. The push-out tests have been performed as a function of borehole (plug) radius and plug length. The use of fo...

Bentonite has been proposed as a primary material for sealing shafts of nuclear waste repositories. It possesses low permeability, chemical and physical stability, and compatibility with most host rock masses and groundwater chemistries. This paper investigates the construction properties of bentonite and evaluates the use of dynamic compaction in...

The morphology of the joint interface is described using geostatistical parameters such as the sill, range and slope of the initial part of the variogram. The methodology is also used to identify the scale effect and to determine the appropriate cutoff length of the sample which is representative for a direct shear test. The anisotropy characterist...

Current designs of the shaft sealing system for the Waste Isolation Pilot Plant (WIPP) propose using bentonite as a primary sealing component. The shaft sealing designs anticipate that compacted bentonite sealing components can perform through the 10,000-year regulatory period and beyond. To evaluate the acceptability of bentonite as a sealing mate...

This chapter presents design process, criteria and considerations for sealing boreholes in rock, with a main emphasis on the hydraulic and mechanical performance of the emplaced seals. The scope of the present information is intended to cover various types of borehole and sealing materials designed for different objectives and requirements. While t...

Sealing of boreholes and underground excavations has not received much engineering attention until fairly recently. The growing awareness of and sensitivity to environmental concerns of the technical community as well as of the public at large has resulted in an increasing recognition of the fact that these geological penetrations may have an envir...

This paper presents results of laboratory compaction testing to determine the influence of particle size, size gradation and moisture-content on compaction of crushed rock salt. Included is a theoretical analysis of the optimum size gradation. The objective is to evaluate the relative densities that can be achieved with tamping techniques. Initial...

The results of a research project into blast-induced rock movement at the Coeur Rochester mine are reported. A total of six blasts were overseen employing the Quarryman laser profiler to locate internal and surface markers. It was discovered that on average 17.7-28.5 feet horizontal movement took place with a powder factor of 0.57-0.76 Lb heavy ANF...

Flow tests have been conducted on expansive cement grout plugs with diameters of 160 mm and 200 mm, and length-to-diameter ratios of one, in boreholes in basalt blocks and in steel pipes. Two types of flow tests have been performed: pseudo-constant head tests and transient pulse tests. Hydration temperatures of cement grout plugs have been monitore...

Exploratory boreholes, shafts and tunnels drilled or excavated prior to or during the construction of a subsurface nuclear repository may create direct passages for radionuclide transport to the biosphere. Waste isolation at the Yucca Mountain repository suite will require that penetrations (boreholes, shafts, etc.) of the geological barrier be sea...

The discontinuities in a rock mass usually control its overall behavior. Rock mass deformability, stability of underground excavations, and flow of fluid depend significantly on the intensity, the degree of interconnection, and the characteristics of the fracture network present. We apply the theory of fractal geometry to describe the rock fracture...

Gas slip phenomena in low-permeability media are typically accounted for by means of the conventional Klinkenberg correction. This correction is derived from gas permeability tests conducted under different pore pressures. An alternative method for obtaining the Klinkenberg correction is given which uses the results from gas permeability tests cond...

A numerical procedure has been developed for predicting dilation (porosity) and gas permeability changes in rock salt. The hierarchical single-surface constitutive model of Desai and co-workers is used a finite element program to calculate the state of stress and strain surrounding excavations in rock salt. The elastoplastic constitutive model acco...

An empirical failure criterion is formulated by expressing the second invariant of stress deviation at failure as a function of the first invariant of stress, key parameter, and volume. Strength data from Apache Leap tuff specimens are analyzed as a demonstration example. The density variable included as a key parameter for this tuff minimizes the...

This study includes a systematic investigation of the sealing performance of bentonite and bentonite/crushed rock plugs. American Colloid C/S granular bentonite and crushed Apache Leap tuff have been mixed to prepare samples for laboratory flow testing. Bentonite weight percent and crushed tuff gradation are the major variables studied. The sealing...

The stability of boreholes, or more generally of underground openings (i.e. including shafts, ramps, drifts, tunnels, etc.) at locations where seals or plugs are to be placed is an important consideration in seal design for a repository (Juhlin and Sandstedt, 1989). Borehole instability or borehole breakouts induced by stress redistribution could n...

Gas permeability and porosity measurements have been made during hydrostatic and triaxial quasi-static, stress-rate controlled compression tests. The permeability and porosity of the as-received samples decrease significantly as a result of hydrostatic loading. These changes are largely irreversible, and are believed to "heal" or return the rock to...

Drilling-induced fractures in borehole walls are investigated by ring tests, flow tests, and microscopic studies. Each drilling method producescharacteristic fracture patterns in the hole wall. Weaker rock drilled withlarge drill bits shows more intense damage than stronger rock drilled withsmall bits. The fracture zones, usually less than 5% of th...

An outline of topics we need to understand better in order to apply mining technology to a nonterrestrial environment is presented. The proposed list is not intended to be complete. It aims to identify representative topics that suggest productive research. Such research will reduce the uncertainties associated with extrapolating from conventional...

The Small-Scale Mine-By was an in situ experiment to measure changes in brine and gas permeability of rock salt as a result of nearby excavation. A series of small-volume pressurized brine- and gas-filled test intervals were established 8 m beneath the floor of Room L1 in the WIPP underground. The test intervals were isolated in the bottom of the 4...

An empirical criterion is formulated to describe the compressive strength of the densely welded Apache Leap tuff. The criterion incorporates the effects of size, L/D ratio, loading rate and density variations. The criterion improves the correlation between the test results and the failure envelope. Uniaxial and triaxial compressive strengths, Brazi...

Bentonite is known to have an extremely low permeability and a self-healing ability. It has therefore been selected as a major sealing component in several repository concepts. Bentonite grouts have the following advantages, (1) small particle size, can be injected into small fractures or voids, (2) suitable water absorption properties, can produce...

The use of bentonite/crushed rock mixtures to form hydraulic barriers has greatly increased in recent years. To obtain an appropriate composition for such mixture sealants generally requires extensive laboratory work. Bentonite content and gradation of the crushed rock component are two key parameters in the seal design. This study investigates the...

Currently under study by the Department of Energy are the geologic and hydrologic characteristics of the ash-flow deposits under Yucca mountain at the Nevada test site. Of interest at this site is the potential for disposal of high-level radioactive wastes in the unsaturated zone of the densely welded portions of the tuffs. These studies include th...

Fractures in the rock mass surrounding a repository and its shafts, access drifts, emplacement rooms and holes, and exploratory or in-situ testing holes, may provide preferential flowpaths for the flow of groundwater or air, potentially containing radionuclides. Such cracks may have to be sealed. The likelihood that extensive or at least local grou...

Axial loads on plugs or seals in an underground repository due to gas, water pressures and temperature changes induced subsequent to waste and plug emplacement lead to shear stresses at the plug/rock contact. Therefore, the bond between the plug and rock is a critical element for the design and effectiveness of plugs in boreholes, shafts or tunnels...

Changes in brine and gas permeability of rock salt as a result of nearby excavation (mine-by) have been measured from the underground workings of the WIPP facility. Prior to the mine-by, the formation responds as a porous medium with a very low brine permeability. The mine-by excavation creates a dilated, partially saturated zone in the immediate v...

The objective of this study is to investigate the time-dependent consolidation of confined crushed salt under axial loading. The crushed salt is geometrically characterized in terms of its grain size distribution and by means of particle shape determinations. Crushed salt of a selected grain size distribution is emplaced in a steel cylinder, and an...

This report presents results of a series of push-out tests performed on cement plugs emplaced in salt cores. Two types of cement have been tested in salt cores drilled from blocks obtained from a mine in a bedded salt formation. Experiments on rock (salt) bridges provide a reference basis. Test durations vary from minutes to two days. A rather broa...

Constitutive law parameters are determined from salt behavior characterization experiments. The results are applied to predict creep (time-dependent) closure of boreholes in salt specimens subjected to various loading configurations. Rheological models (linear and nonlinear viscoelastic and viscoplastic models), empirical models, and physical theor...

An experimental sealing performance assessment of cement borehole plugs that have been subjected to dynamic loading is provided. This includes a study of plugs that have dried, as well as of plugs that have remained wet throughout the testing period. An introductory literature review indicates that deep underground structures in competent rock are...

Boreholes near a repository must be sealed to prevent rapid migration of radionuclide-contaminated water to the accessible environment. The objective of this research is to assess the performance of borehole seals under laboratory conditions, particularly with regard to varying stress fields. Flow through a sealed borehole is compared with flow thr...

Flow tests have been conducted on cement plugs with diameters of 158.8 mm and 196.9 mm, and length to diameter ratios of one, in boreholes in basalt blocks and in steel pipes. Expansion strains and curing temperatures have been monitored on cement plugs in boreholes in basalt blocks, in PVC and in steel pipes with diameters from 25.4 mm to 196.9 mm...

Ring tension tests, permeability tests, and microscopic fracture studies have been performed to investigate the borehole damage induced at low confining pressure by three drilling techniques (diamond, percussion and rotary). Specimens are drilled with three hole sizes (38, 76, and 102 mm diameter) in Pomona basalt and Grande basaltic andesite. The...

Flow tests have been conducted on cement plugs with diameters of 158.8 mm and 196.9 mm, and length to diameter ratios of one, in boreholes in basalt blocks and in steel pipes. Expansion strains and curing temperatures have been monitored on cement plugs in boreholes in basalt blocks, in PVC and in steel pipes with diameters from 25.4 mm to 196.9 mm...