実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report
29, August, 2017

課題番号 Project No.

装置責任者 Name of responsible person

2017A0031

Kazuya AIZAWA

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Strain analysis in rock materials using Neutron diffraction and AE signal measurement

Engineering

実験責任者名 Name of principal investigator“TAKUMI” (BL-19)

Jun ABE実施日 Date of Experiment

所属 Affiliation

13, May, 2017 – 16, May, 2017

Materials

Diffractometer

Comprehensive Research Organization for Science and Society
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
-Sandstone, SiO2, phi 25 x L 50 mm

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

To investigate the mechanical behavior of rocks, the strain measurements in rock specimens under uniaxial
compression have been performed. Simultaneously, AE signals have also been measured. The experimental
setup is shown in Figure1. The resolution (∆d/d) and the d-value range for neutron diffraction experiments
were 0.3 % (medium-resolution mode of TAKUMI) and 1.4-4.2 Å (frame shift mode), respectively. In parallelwith lattice strain measurements using neutron diffraction technique, macroscopic strain values wererecorded using a strain gauge attached to the surface of a rock specimen. The AE signals were measured
using PCI-2 (PHYSICAL ACOUSTICS CORP.). AE waves were detected using AE sensors (Micro 30 or Pico)attached to the compression jigs. The threshold was 40 dB was applied; this threshold level was 2-3 dB higher
than noise level. The sampling rate was 10 MHz and the sampling time was 1 msec. Uniaxial compression
loading was performed in a step-loaded manner, with a holding time of more than 600 sec. during which
neutron diffraction patterns were obtained. The loading rate was 2.4 MPa/min with compression being applied
until the rock specimen fractured.
12. 実験方法及び結果（つづき） Experimental method and results (continued)

Figure 1. (a) Photograph of the experimental setup for in uniaxial compression. To avoid scattering of sample
fragments when a rock sample was broken, aluminum cover was equipped. Cylindrical rock specimen was set in thisaluminum cover. (b) Photograph of a rock specimen set inside the aluminum cover. Sensors for AE signal
measurement were attached to the compression jig.

Figure 2 shows a stress-strain curve. A discrepancy is found between macro strain and lattice strain; macro
strain is larger than lattice strain. And macro strain exhibits a curve indicating plastic deformation behavior
whereas lattice strain exhibits elastic behavior.
Figure 3 shows the result of AE signal measurement together with the loading program (black solid line,right-handed axes). The number of AE events per 10 sec. is indicated as a red bar chart (Figure 3(a)), and theamplitudes of each AE events are indicated as blue circles (Figure 3(b)). AE signals tended to be detectedduring the experiments when the applied load was increased. However, at higher loading condition, AE signals
were detected when the applied load was kept. The amplitudes of AE signals were almost constant underloading condition. Many high-amplitude AE events were generated at the time of fracture occurrence. The AE
events might be correlated to internal structure change of rock sample, such as grain slip and/or micro crack
initiation.
The data analysis is under way.

Figure 2. Stress-strain curve. Macroscopic strain
measured by a strain gauge is denoted by solidlines, and lattice strain evaluated from the change inlattice parameter value is plotted as circles.

Figure 3. Results of AE signal
measurements together withthe loading program. (a) The
number of AE events per 10
seconds,and(b)theamplitudes of each AE signals
are indicated.

2