Predicting the Schmidt hammer values of in–situ intact rock from core sample values

2002 ◽  
Vol 39 (3) ◽  
pp. 395-399 ◽  
Author(s):  
S Kahraman ◽  
M Fener ◽  
O Gunaydin
Keyword(s):  
Core Sample ◽  
Intact Rock ◽  
Schmidt Hammer

scholarly journals Seasonal dynamics of Daphnia laevisBirge, 1878 ephippia in a tropical lake with a description of a new methodology for in situ evaluation

2014 ◽  
Vol 74 (3) ◽  
pp. 642-648 ◽  
Author(s):  
LPM Brandão ◽  
DGF Pujoni ◽  
PM Maia-Barbosa
Keyword(s):  
Water Column ◽  
Seasonal Dynamics ◽  
Thermal Stratification ◽  
Core Sample ◽  
Hatching Rate ◽  
The Core ◽  
Significant Difference ◽  
Chi Squared ◽  
Hatching Rates

The effect of dormancy in zooplankton populations is still unknown, largely because of the lack of methods to estimate hatching and production of the dormant stages. This study aimed to compare the production and hatching rates of ephippia of Daphnia laevis between thermal stratification and mixing periods in Jacaré Lake (Middle Rio Doce, Minas Gerais, Brazil). For this, we collected ephippia on the sediment with core sampler and we created a device called the “Ephippial Collector”. There was a significant difference in ephippia hatching in situ between stratification and mixing periods (Pearson's Chi-squared test p <0.001), being higher in the second one. Significant differences in the hatching rates between periods was observed in the laboratory only for ephippia collected with Ephippial Collectors (Pearson's Chi-squared test p <0.001), being higher during the mixing period (∼8%). The core sample allows the collection of a certain fraction of the sediment that may contain a mixture of ephippia produced in different periods, i.e., may contain old and not viable ephippia, which masks the hatching rate. Thus, seasonality in hatching rates of ephippia was reported only by Ephippial Collectors. The higher hatching rate observed during the mixing period in the lake suggests that individuals hatched from ephippia may contribute to the increase in the population of D. laevis in the water column at this time.

scholarly journals Characterization of Historic Binders and Stones of a Ruined Medieval Church (Hungary)

2020 ◽  
Author(s):  
Zsuzsanna Kósa ◽  
Ákos Török
Keyword(s):  
Moisture Content ◽  
Construction Materials ◽  
Selective Dissolution ◽  
Test Methods ◽  
Schmidt Hammer ◽  
Fine Grained ◽  
Medieval Church ◽  
History Of ◽  
Non Destructive

Construction materials of a partly ruined Medieval church of Central Hungary were studied in details to assess its conditions and to obtain information on the phases of construction. At first, digital images were taken to create a 3D model of the remaining walls. The material properties were measured in situ using non-destructive test methods. Strength parameters of stone and render were assessed by Schmidt hammer, while moisture content was measured by a portable moisture meter. According to lithological descriptions and thin-section analyses limestone prevail in the monument. The most common Miocene limestone is represented by various lithologies, such as cemented macro porous limestone, fine-grained porous limestone, oolitic limestone and bioclastic limestone. Mesozoic micritic well cemented limestone and Tertiary limonitic sandstone were also identified at the ruins. The most common weathering forms are selective dissolution, multiple flaking and biological colonisation. Renders used in the structure represents the long history of the structure from Medieval lime-based mortars to Portland cement containing latest applications. The former one is composed of quartz send in lime binder. According to Schmidt hammer tests, the rebound values of the replacement stone is higher than that of the original porous limestone. There is a distinct difference in the moisture content of the stone and render. Orientation/exposure of the wall also influences the moisture content. The gathered information allows for designing better repair methods and helps in the planning of the maintenance of the medieval stone heritage.

Coupled Hydro-Mechanical Modeling of Fracture Normal Displacement and Fluid Pressures during a SIMFIP (step-rate injection method for fracture in-situ properties) Test

2020 ◽  
Author(s):  
Alexandru Tatomir ◽  
Farzad Basirat ◽  
Chin-Fu Tsang ◽  
Yves Guglielmi ◽  
Patrick Dobson ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Intact Rock ◽  
Normal Displacement ◽  
Hydrogeology Journal ◽  
Finite Volume Scheme ◽  
Test Interval ◽  
Injection Method ◽  
Step Rate ◽  
Hydraulic Aperture

&lt;p&gt;Characterization of coupled hydro-mechanical (HM) processes in rock fractures is important for several key geosciences applications, such as rock slope stability, enhanced geothermal systems, and hydraulic fracturing. In-situ experimentation of these processes is challenging, and presently very few techniques exist for quantifying the parameters needed to calibrate hydromechanical models for fractured rocks at field scales. One recent field technology is the step-rate injection method for fracture in-situ properties (SIMFIP) developed by Guglielmi et al. (2014). The method measures simultaneously the time evolution of flow rate, pressure and three-dimensional deformation of the test interval at high resolution.&lt;/p&gt;&lt;p&gt;In June 2019 a set of SIMFIP experiments was carried out in &amp;#197;re, Sweden, in the COSC-1 borehole. This is a 2.5 km deep borehole aimed primarily for scientific investigations and the fractures and intact rock sections in the borehole are well characterized. Based on the earlier characterization work, three sections were selected for SIMFIP testing: one intact rock section, one section containing a conductive fracture and one section containing a non-conductive fracture (Niemi et al., in prep.).&lt;/p&gt;&lt;p&gt;In this study, a coupled HM model is developed to represent the key coupled processes occurring during these SIMFIP tests. A fully-coupled vertex-centered finite volume scheme and a decoupled finite element model are implemented independently to simulate the elastic deformations and changes in pressure induced by the step-rate injection or flow back of given water volumes. Specifically, the two models are implemented in the commercial simulator COMSOL Multiphysics (sequentially coupled FEM), and the free-open source academic code DuMu&lt;sup&gt;X&lt;/sup&gt; based on the models of Beck (2019). The models are used to match the pressure recorded by the high precision sensors in the test interval. A parametric study is carried out to mimic the fracture extension and step-down stages of the experiments and to investigate the influence of the key hydromechanical parameters (hydraulic aperture, permeability, storativity, and elastic moduli) on the observed data. The resulting coupled hydromechanical model will be further developed to study the three-dimensional deformation of the borehole section under the SIMFIP test.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Beck M (2019) Conceptual approaches for the analysis of coupled hydraulic and geomechanical processes. Ph.D. Thesis, Stuttgart University&lt;/p&gt;&lt;p&gt;Guglielmi Y, Cappa F, Lan&amp;#231;on H, Janowczyk JB, Rutqvist J, Tsang CF, and Wang JSY. (2014) ISRM Suggested Method for Step-Rate Injection Method for Fracture In-Situ Properties (SIMFIP): Using a 3-Components Borehole Deformation Sensor. Rock Mech Rock Eng 47:303&amp;#8211;311. https://doi.org/10.1007/s00603-013-0517-1&lt;/p&gt;&lt;p&gt;Niemi, Auli, Yves Guglielmi, Patrick Dobson, Paul Cook, Chris Juhlin, Chin-Fu Tsang, Benoit Dessirier, Alexandru Tatomir, Henning Lorenz, Farzad Basirat, Bjarne Almqvist, Emil Lundberg and Jan-Erik Rosberg 'Coupled hydro-mechanical experiments on fractures in deep crystalline rock at COSC-1 &amp;#8211; Field test procedures and first results&amp;#8217;. Manuscript under preparation, to be submitted to Hydrogeology Journal.&lt;/p&gt;

On the accuracy of the in-situ Schmidt hammer test on carbonate rocks

2013 ◽  
pp. 189-193 ◽  
Author(s):  
H Arman ◽  
W Hashem ◽  
O Abdelghany ◽  
A Aldahan
Keyword(s):  
Carbonate Rocks ◽  
Schmidt Hammer

A CONFIRMATION BY GRAVITY MEASUREMENTS OF AN UNDERGROUND DENSITY PROFILE BASED ON CORE DENSITIES

Geophysics ◽  
1965 ◽  
Vol 30 (6) ◽  
pp. 1108-1132 ◽  
Author(s):  
Thane H. McCulloh
Keyword(s):  
Sedimentary Rocks ◽  
Core Sample ◽  
Mine Shaft ◽  
Density Profiles ◽  
Sample Density ◽  
Gravity Measurements ◽  
Natural Density ◽  
Bulk Volume ◽  
Gravity Variations

Accurate laboratory measurements of dry bulk densities of 79 samples of Paleozoic sedimentary rocks from a 2,851‐ft deep core hole near Barberton, Ohio, are the basis of a vertical profile of “natural” density which differs on the average [Formula: see text] or less from a profile of in‐situ density calculated from gravity variations observed using a LaCoste and Romberg gravimeter in an adjacent 2,247‐ft‐deep vertical mine shaft. Both profiles agree well with the most meaningful Barberton core sample densities reported by Hammer (1950, Fig. 3), but are significantly lower than in‐situ interval densities calculated by Hammer from gravity variations observed in the shaft using a Gulf gravimeter. The [Formula: see text] average discrepancy between the old and new in‐situ density profiles is probably attributable to a 12‐percent error in calibration of the Gulf gravimeter. The close agreement between the new profiles of “natural” and in‐situ density suggests that changes in bulk volume of compact sedimentary rocks that occur during or following the coring process are probably ordinarily so small that properly constructed core sample density profiles are reproducible and reliable even when small numbers of samples of aged cores are used. If they are to be used for determination of in‐situ density, underground gravity measurements must be accurate as well as precise.

scholarly journals In Situ Measurements in Fractured Till Using Sidewall Sensors

1999 ◽  
Vol 30 (4-5) ◽  
pp. 257-266 ◽  
Author(s):  
Larry Murdoch ◽  
Bill Harrar ◽  
Bertel Nilsson ◽  
William Slack ◽  
Robert Siegrist
Keyword(s):  
Hydraulic Head ◽  
Core Sample ◽  
Contaminated Site ◽  
Platinum Electrodes ◽  
Glacial Sediments ◽  
Fine Grained ◽  
In Situ Sensors ◽  
The Usa ◽  
A Site

Subsurface parameters, such as hydraulic head, often vary markedly with depth in fine-grained glacial sediments, but sensors placed in vertical boreholes are poorly suited to resolve these variations. One problem is that conventional methods only allow one, or perhaps a few, sensors to be placed in each borehole. To address such limitations we have developed a method for accessing the sidewall of a borehole. The method uses a device that pushes sensors or sediment samplers laterally into the sidewall to distances slightly less than the diameter of the borehole. The device can obtain a core sample 15 cm long and 4 cm in diameter, and then insert a permeable sleeve for extracting water samples. The same device has been used to insert several types of electrodes capable of measuring water content (using TDR waveguides), Eh (using platinum electrodes), or electrical resistivity (using a miniature Wenner-type array). At a site near Flakkebjerg, Denmark, we installed 22 water samplers and 19 resistivity electrodes in a single borehole to measure hydraulic head gradients in detail and to monitor the vertical migration of ionic tracers. This approach can be used to install horizontally oriented TDR waveguides at virtually any depth, thereby extending the TDR technique to the study of deep vadose zones. At a contaminated site in the USA, TDR wave guides were installed to a depth of 12 m in glacial till. Other applications include measurement of Eh at a site where in situ chemical oxidization was used, and the in situ sensors provided results that are similar to data obtained from soil cores.

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