Jack Test Research Articles

Evaluation of a specific balance and coordination programme for individuals with a traumatic brain injury

The purpose of this study was to evaluate the effectiveness of an aerobic dancing training, designed to reduce postural imbalance and coordination deficits for individuals who had sustained a traumatic brain injury (TBI). A two group experimental design was conducted. A control group participated in a traditional muscular training (TMT) programme while participants in the experimental group were assigned to an aerobic dancing, Slide and Step training programme (specific training group (ST)). Participants were evaluated pre- and post-training. Balance was quantified using a force platform and coordination using a Peak Performance system to compare the velocity profiles of a modified Jumping jack test. Results showed that temporal variables were significantly different pre- and post-training for the ST group, but no changes were found in the TMT group. The results of the balance test indicated a significant reduction of postural sway area in the ST group but not in the TMT group. Overall, the combination workout with Step and Slide is more effective in reducing balance and coordination deficits when compared to muscular based training.

The deformation modulus of rock masses — comparisons between in situ tests and indirect estimates

Three methods of in situ deformation modulus (Em) measurements of rock masses have been described, analysed and compared. The plate jacking (PJT) test, where the deformations are measured by extensometers in drill holes, gives generally the best results. A factor of 2.5 has been found between PJT and the Goodman jack test, and the plate loading test. From analyses of the results it has been pointed out that the damage from blasting of the test adit reduces the magnitude of test results with a factor between 2 and 4. The existing equations for indirect estimates of the rock mass deformation modulus from classification systems have been analysed and adjustment suggested. Taking into consideration the uncertainties connected to in situ deformation measurements caused by blast damage, test procedure and test method, a good characterization of the ground may give comparable, or possibly better Em values, using the RMi or the RMR system than the in situ tests. The RMR system gives, however, values that are too high for Em in massive rock.

Mesure du module en petites déformations d'un sol autour d'une conduite enterrée : présentation d'un nouvel essai in situ

A new method of measurement of backfill stiffness around buried flexible pipe is presented. It consists of using flexible pipe as an expanding pressiometric probe. The pipe dilatation is obtained by an internal jacking test that causes a relatively small three-dimensional "ovalization" around 0.05%. We obtain a force-displacement curve along the force axis as well as the damping of the displacement in the longitudinal direction up to one diameter in range. Knowing the pipe mechanical characteristics, we can calculate Young's modulus of the backfill in the domain of small deformations. The paper describes the test procedure as well as the modulus computation technique, which is based upon a three-dimensional parametric study using the finite element method. The results obtained in a jacking test conducted on iron pipe of 1.4 m in diameter and 8.0 m in length are presented. The computed moduli are compared with the ones obtained in laboratory testing using resonant-column and cyclic triaxial tests.Key words: buried pipes, jacking test, soil stiffness, soil-structure interaction, three-dimensional analysis, finite elements.

堆積軟岩での立坑掘削に伴う岩盤物性変化の現場計測による検討

A shaft with an inner diameter of 6 m has been excavated by blasting in Tertiary soft sedimentary rocks and we have estimated the changes of rock properties, such as deformation modulus, permeability and fracture frequency, of the rock around the shaft. We have performed four kinds of in-situ investigations; borehole jack test, cross-hole seismic velocity measurement, water injection test and borehole television survey. We have carried out these investigations before and after the shaft excavation in the same locations, with the same sets of equipment and through the same procedures for accurate estimation of rock property changes induced by the shaft excavation. The measurement locations have been selected in order to estimate the dependency of the excavation disturbance on the distance from the shaft wall and geological conditions such as lithology and faults. Within 0.5 to 1 m from the shaft wall, detectable property changes have been observed. In the rock zone, some kinds of deformation moduli have decreased. On the other hand, the number and apertures of fractures have increased and permeability has also increased by 2 ~ 3 orders of magnitude in the rock zone. Blasting damage is supposed to be the main factor which has induced these rock property changes considering strength and stress condition of the rock. Effectiveness of each investigation method in the estimation of excavation disturbance is also discussed.

Effect of intermediate principal stress on strength of anisotropic rock mass

The Mohr-Coulomb criterion needs to be modified for highly anisotropic rock material and jointed rock masses. Taking σ 2 into account, a new strength criterion is suggested because both σ 2 and σ 3 would contribute to the normal stress on the existing plane of weakness. This criterion explains the enhancement of strength ( σ 2 – σ3) in the underground openings because σ 2 along the tunnel axis is not relaxed significantly. Another cause of strength enhancement is less reduction in the mass modulus in tunnels due to constrained dilatancy. Empirical correlations obtained from data from block shear tests and uniaxial jacking tests have been suggested to estimate new strength parameters. A correlation for the tensile strength of the rock mass is presented. Finally, Hoek and Brown theory is extended to account for σ 2. A common strength criterion for both supported underground openings and rock slopes is suggested.

A comparison of uniaxial and borehole jack tests at Fort Providence ice crossing, 1995

A field test program was conducted on the ice bridge crossing near Fort Providence, Northwest Territories, during March 1995. Cores of ice were extracted and tested on a portable test frame in uniaxial compression at a strain rate of 2 × 10 n3 s n1 . The ice temperature varied from n6 to n15∞C over the course of the tests. In the core holes, in situ strength tests were performed using a borehole jack. Tests were conducted in both the natural ice and the sprayed ice to obtain a correlation between uniaxial compression strengths and the strengths obtained by the borehole jack. Based on our results and previous practice, the factor of safety for the ice crossing against flexural failure was about 4.

Design aspects of the underground structures of the Serra da Mesa Hydroelectric Power Plant

The Serra da Mesa Hydroelectric Power Plant, located in the Tocantins river, 210 km north of Brasilia, Brazil, is under construction and power generation will start in 1998. The installed power capacity is 1,200 MW. This project includes one of the largest underground power plants in Brazil, totaling 550,000 m 3 of underground excavations for the hydraulic circuit. The underground hydraulic circuit, composed by 3 intake tunnels, 3 pressure tunnels, a powerhouse cavern, 3 suction tunnels, a surge chamber, an tailrace tunnel and 8 shafts, was excavated in a very high quality granite. Laboratory and in-situ tests, including hydraulic fracturing, small flat jack and triaxial tests, were carried out to determine the in-situ stress tensor and the geomechanical properties of the rock. Test results were summarized to yield parameters for a 3D numerical simulation of the structures, using the Boundary Element Method. Results in terms of strength factors, using the Mohr-Coulomb and Drucker-Prager criteria, are presented and discussed. Copyright © 1997 Elsevier Science Ltd

Foundation studies for theodore roosevelt dam

Theodore Roosevelt Dam, on the Salt River northeast of Phoenix, Arizona, was originally constructed as an 85.3m-high arched masonry dam between 1903 and 1911. Modifications were completed in 1996, which included raising the dam 23.5 m for dam safety puroses and additional water supply. The dam is founded on Precambrian sandstone, siltstone, and dolomite. Occasional clay partings parallel the bedding, which dips upstream at 25 to 30 degrees. The studies performed for raising the dam considered deformation, stability, and seepage characteristics of the foundation rock mass to ensure it could safely withstand the additional loading. Seismic tomography and in situ jacking tests were used to characterize the deformation properties. Piezometers were installed to measure foundation water perssures before and after drainage measures. Critical clay partings and joints were sampled and tested for shear strength, and foundation blocks with the potential to move under loads applied by the dam and reservoir were analyzed three dimensionally for potential sliding under normal, flood, and time-varying earthquake conditions. Foundation treatment was performed based on the results of the studies.

A comparison of uniaxial and borehole jack tests at Fort Providence ice crossing, 1995

A comparison of uniaxial and borehole jack tests at Fort Providence ice crossing, 1995

Effect of tunnel depth on modulus of deformation of rock mass

Deformability of rock mass significantly influences its behaviour and is, therefore, an important consideration for the design of underground openings. The modulus of deformation of rock mass is, however, normally obtained from expensive and time-consuming uniaxial jacking tests, whose results often have a large scatter. An empirical correlation has, therefore, been proposed for a quick and inexpensive preliminary estimation of the modulus of deformation of rock mass on the basis of field instrumentation carried out in tunnels in India.

A cyclic hydraulic jacking test to determine the in situ stress normal to a fracture

Hydraulic fracturing and cyclic hydraulic jacking (step-pressure) tests were used to determine the virgin stress normal to six natural joints in grantic rocks. A numerical model was used to analyse the coupled problem of fluid flow and rock/fracture deformation during the field tests. Fracture closure and virgin normal stress was determined from the zero-flow pressure in a well pressure-well flow diagram. The cyclic hydraulic jacking tests gave a zero-flow pressure in close agreement with both the shut-in pressure and the weight of the overburden rock for four out of six tested joints. For the two remaining joints the virgin normal stress could be estimated by a linear extrapolation to zero-flow rate. The zero-flow pressure is clearly defined and is insensitive to the transmissivity and non-linear normal stiffness of the fracture near the wellbore. Cyclic hydraulic jacking is therefore an alternative to traditional shut-in analysis when shut-in pressure is difficult to determine.

Interpretation of in situ borehole ice strength measurement tests

A hydraulic borehole jack for the testing of ice confined compressive strength and elastic modulus through the depth of a 150 mm hole at regular intervals is described. Interpretation of the pressure and deformation information obtained is accomplished using standard equilibrium and compatibility equations for plate bearing tests applied to the expansion of a cavity of crushed material surrounded by an elastic medium. The jack tests yield confined compressive strength and elastic modulus. These are basic, universally understood, engineering properties of a material useful in practice. The jack has been used successfully to determine the in situ strength and stiffness at any combination of depths required in a wide variety of conglomerate freshwater and sea ice. The results have been used to verify the strength and bearing capacity of ice platforms and roads and to help quantify global ice loads and local ice pressures on offshore structures. Key words: ice, ice testing, borehole testing, ice strength, ice roads, ice structures, field testing, field strength testing, in situ strength, in situ testing, ice in situ testing, ice platforms.

Theoretical and field studies of coupled hydromechanical behaviour of fractured rocks—2. Field experiment and modelling

A series of water injection experiments were performed on four horizontal fractures intercepted by a borehole at the University of Luleå Rock Mechanics Laboratory site in Sweden. The fractures are located in a borehole section 80–350m in depth. Three types of injection tests were carried out: (1) constant-pressure injection tests, with pressures ranging from below to above the overburden pressure; (2) constant-flowrate injection tests; and (3) step pressure tests (hydraulic jacking test). In the former two cases, the results clearly depict the coupled effect of mechanical fracture-aperture opening due to increased hydraulic pressure, even in the pre-hydrofracturing regime. A parallel numerical study was carried out to simulate these injection tests using the computer code ROCMAS II [see Part 1, Int. J. Rocl Mech. Min. Sci. & Geomech. Abstr. 29, 401–409 (1992)]. We were able to simulate closely the pre-hydrofracturing coupled effect in the step pressure and constant pressure test. The success in this attempt validates the soundness of the conceptualized constitute relations governing the coupled hydromechanical behaviour of rock masses. The results also point out a potential methodology of using a joint field and theoretical study of fracture hydromechanical responses to extract key characterizing parameters of the rock and fractures.

Engineering geology of the Miner Flat dam, Navajo County, Arizona

The proposed Miner Flat dam will be across the North Fork of the White River just below the Mogollon Rim on the White Mountain Apache Indian Reservation, Arizona. The dam will be approximately 46 m high with a crest length of about 80 m and will be either a gravity concrete or roll-crete dam. The dam will fill a canyon cut in Tertiary/Quaternary basalt. The basalt, in a series of flows, filled an ancestral channel of the White River. The ancestral channel had alluvium in the bottom and colluvium along the walls, which, in part, were incorporated into the base of the basalt flows. The bedrock below the basalt and the paleocolluvium/paleoalluvium is a sandstone of the Upper Limestone and Siltstone Member of the Supai Formation of Pennsylvanian/Permian age. The sandstone bedrock is almost flat-lying. The basalt flows, in general, dip gently downstream. The sandstone is grossly jointed and the upper part of the basalt flows are columnar. No faults occur in the area. Geotechnical investigations included drilling for core, digging test pits in unconsolidated material and geophysical surveys. The core was logged, point load tests were made on the core and packer tests and Goodman jack tests were made in the drill holes. Based on the point load tests, the strength of the basalt ranged from about 6.60 to 290 MPa, the sandstone of the Supai Formation about 0.1–96 MPa and the siltstone averaged from 1.6 to 96.4 MPa. The packer tests gave hydraulic conductivities in the basalt of 1.15 × 10 −4−5.20 × 10 −8cm/sec , in the paleocolluvium/ paleoalluvium of 1.06 × 10 −4−9.56 × 10 −6cm/sec , and in the siltstone and sandstone of the Supai Formation of 1.73 × 10 −3to3.33 × 10 −7cm/sec . Youngs modulus ( E), as determined, from Goodman jack tests, ranged from 0.34 to 2.76 in the basalt and 0.07–53.91 in the paleocolluvium/paleoalluvium. The test pits, geophysical surveys and laboratory testing indicate that there are about 150,000 m 3 of good quality aggregate available for construction. The geological and geotechnical investigation, of the proposed dam and reservoir site established that there were no fatal flaws to the construction of the dam and reservoir. Of particular concern was the possibility of lava tubes or zones of high permeability between the lava flows at the abutments and in the reservoir area; none were identified. Also of concern was the permeability of the paleocolluvium/alluvium beneath the basalt in the reservoir area. The investigations establish that this would not be a problem. Additional geotechnical investigations will be required for final design.

Post-test assessment of simulations for in situ heater tests in basalt—Part I. heater test description and rock mass properties

Thermomechanical simulations were undertaken both a priori and a posteriori for two full-scale heater tests in shallow tunnels at the Near Surface Test Facility (NSTF) at Hanford, Washington. The Basaltic rock mass was investigated by an extensive laboratory and field programme involving geological characterization, core drilling and borehole testing, a field thermal test and a large-scale in situ flat jack test isolating 8 m 3 of columnar basalt. Rock mass thermal and mechanical properties were determined from these characterization data for input into thermomechanical simulations. The heater test systems are described along with the instrumentation, which consisted of numerous thermocouples, borehole extensometers, borehole deformation gauges and vibrating wire stressmeters. The determination of the rock mass thermal and mechanical properties from laboratory test data, geological characterization data and back-analysis of field property tests are detailed. The idealization of the basaltic rock mass was determined from interpretation of extensive geological characterization data; involving detailed field geologic mapping, borehole and core logging, rock mass classification schemes, impression packer tests, borehole geophysical tests, borehole jack deformation tests and laboratory and field experiments.

Comparison of rock mass deformabilities determined using large flat jack technique and plate jacking test at two dam sites : Ozgenoglu, A; Pasamehmetoglu, A G; Karpuz, C Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug–10 Sept 1987V1, P471–474. Publ Rotterdam: A A Balkema, 1987

Comparison of rock mass deformabilities determined using large flat jack technique and plate jacking test at two dam sites : Ozgenoglu, A; Pasamehmetoglu, A G; Karpuz, C Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug–10 Sept 1987V1, P471–474. Publ Rotterdam: A A Balkema, 1987

Predicted and measured rock mass moduli

Plate bearing and rock bolt jacking tests are used to measure the in situ deformational response of four jointed rock masses, namely sandstone, limestone, shale and coal. Samples representing the intact rock and joint material were retrieved from the test sites and examined in the laboratory. While performing the joint shear strength tests, the joint normal and shear stiffnesses were also measured. The predicted values of the rock mass moduli were evaluated using composite theory and the laboratory determined joint stiffnesses and intact rock moduli. When evaluating the predicted rock mass moduli, lower bound composite formulations were used. These predicted rock mass moduli were then compared with the measured in situ deformational moduli. Joint shear stiffness is an order, that is 10 times, less than the joint normal stiffness and this has the important effect of disproportionally increasing the deformational response. The in situ measured moduli correlate reasonably well with the predicted moduli evaluated from the lower bound deformational formulations. However, good correlation is obtained when the lower values of joint stiffnesses are used in the lower bound deformational formulations.

The Borehole Jack—Is It a Useful Arctic Tool?

As the working temperatures in ice are very close to its melting point, it behaves viscoelastically and experiences what is commonly known as high temperature embrittlement. Its mechanical properties are rate sensitive and analysis must include load and displacement history. Borehole jack tests can be improved by the use of an electrohydraulic pump in conjunction with simultaneous recording of pressure and diametral displacement as a function of time. These small but significant modifications in the test procedures permit analysis of the response of a borehole jack test system under operational conditions in the High Arctic in first-year and multi-year sea ice.

Determination of the deformation modulus of rock from tunnel and borehole loading tests : Carter, J P; Booker, J R Proc 4th Australia-New Zealand Conference on Geomechanics, Perth, Western Australia, 14–18 May 1984V2 P509–513. Publ Barton: Inst of Engineers, 1984

Exact solutions are presented for the radial displacement of plates and cylindrical membranes jacked or expanded against the walls of a circular tunnel or borehole. The plates have been assumed as either perfectly flexible or perfectly rigid and the surrounding rock mass has been assumed to behave as a homogeneous, isotropic, linear elastic continuum. The application of these solutions to the interpretation of plate jacking tests in tunnels, small jacking tests in boreholes and pressuremeter tests in boreholes has been discussed. (Author/TRRL)

Recent advances in the interpretation of the flat jack test : Borsetto, M; Giuseppetti, G; Manfredini, G Proc 5th Congress of the International Society for Rock Mechanics, Melbourne, 10–15 April 1983V1, PA143–A151. Publ Rotterdam: A. A. Balkema, 1983

The use of the flat jack test to identify the residual strength of rock masses is discussed. Test interpretation procedures developed by means of numerical models of the slot are presented. The same procedures are applicable to the determination of original stresses as an alternative to the cancellation pressure method recommended by irsm suggested standards. The use of the flat jack for deformability measurements is also analysed and the limitations of the conventional interpretation formula are outlined. The number of the covering abstract of the congress is TRIS no. 385148. (TRRL)