An Experimental Study Of Sandstone Radon In Precipitates Quantity Under The Axial Pressure

For a long time, the earthquake this geological disasters to human production andlife brought great threat, people have been searching for various technical research inearthquake prediction. Earthquake prediction method can be roughly classified intothree categories: earthquake geology, earthquake statistics and earthquake precursors.In earthquake precursor prediction method, radon gas is considered the most promisingone of gas composition, which can be used in earthquake prediction in the role ofradon gas by the earthquake workers more and more attention. Many scholars at homeand abroad based on the earthquake and underground radon gas in the long-termresearch, in this study period earthquake workers not only in theory has enriched thetheoretical basis for radon predict earthquakes, but also through the long timemonitoring, got a lot of system, complete data to support for the theoretical basis. Inthis paper, the different amount of uniaxial pressure in sandstone sample radonexhalation experiment to explore the influence of uniaxial pressure value and therelationship between the radon precipitation granite sample, in order to establish ageological body in the earthquake consolidation stage, the radon exhalation experimentmodel of quantity change. This experiment mainly adopts the method is the use ofindependent research and development of chengdu university of IED–3000Finstantaneous radon measurement instrument with CR-39solid state nuclear trackdetector sandstone samples in the measuring time within the scope of radon exhalationthe dynamic change of quantity and total amount.In this paper, achievements are as follows:1. Through the rock triaxial creep variable testing machine, the water content ofdifferent sandstone and maximum compressive experiments showed that differentsandstone and moisture content of different pressure resistance, pressure resistance ofpurple sandstone was obviously higher than that of yellow sandstone, and dryspecimen compressive resistance significantly higher than the saturated pressureresistance. The experiment of uniaxial pressure gradient, and the study of different condition radon exhalation sample has played a key role.2. In order to simulate the purple sandstone in the compression of the period, thepressure gradient is divided into10kN,20kN and30kN three different uniaxialpressure. By rock triaxial creep turn tester can draw three different uniaxial pressureand the change of the sandstone sample between axial displacement: sample is underuniaxial pressure, the greater the the greater the variation of the axial displacement;Sample in different stages of uniaxial pressure reaches the maximum axialdisplacement time also positively correlated with the size of the uniaxial pressure, theaxial displacement of the strain rate and three different kinds of specimen underuniaxial stress are in logarithm change the axial displacement. For the axialdisplacement curve of three kinds of pressure to function fitting is: when the uniaxialpressure for10kN, fitting function is: y=0.1329ln (x)+0.0229, the fitting is:0.966.When the uniaxial pressure is20kN fitting function is: y=0.1655ln (x)+0.0402, thefitting is:0.9187. When the uniaxial pressure is30kN fitting function is: y=0.2191ln(x)+0.088, the fitting is:0.8827.3. By IED–3000F instantaneous radon measurement instrument measured bycounting the instantaneous results of every half hour graph can be concluded that theshape of the curve trend is growing volatility, two kinds of sandstone samples of radonexhalation has the characteristics of autonomous fits.4. Combined with IED–3000F instantaneous radon measurement instrument andCR-39solid track detector for purple sandstone radon emanation quantity changeunder uniaxial pressure of two kinds of the experimental results show that: in asimulated sample earthquake consolidation stage, purple sandstone sample amount ofradon exhalation and negatively correlated with the size of the uniaxial pressure value.Within the scope of the sample of compressive, due to uniaxial pressure makes thesample "native" the higher the fracture and the closure of some structure, less quantityof samples of radon exhalation. This result also with previous inferences about thenegative anomaly of radon before.5. Through the CR-39solid track detector for two kinds of sandstone samplecracking and broken of measurement results of radon exhalation analysis shows thatdue to the sample under the condition of crack samples and broken samples, itsmicrocracks and the "native" cranny of radon gas migration channel increase, andsome structural plane under the action of super pressure resistance pressure wascompletely destroyed, sample amount of radon exhalation is significantly increased.This result also with predecessors about after the earthquake seismic stations radon appeared the phenomenon of increased obviously.6. The saturated samples are measured results show that the measurement resultsboth instantaneous measurement results and accumulated their change rule and thechange of the sample of the same; Two difference in moisture content, the higher theless amount of sample radon exhalation. By instantaneous radon measurementinstrument measured instantaneous results shows that when the moisture content in asample with falling over time, the amount of radon exhalation there will be a growingphenomenon.7. For two kinds of sandstone in0kN, crack, broken under three states CR-39solid state nuclear track detector linear function of the measurement results of known:linear function of yellow sandstone samples are as follows: y=44.585x+165.66, thefitting is:0.9957. Linear function of purple sandstone are as follows: y=41.161x+153.71, fitting for:0.9945, the fitting degree of both types is better.