Preparation Method and Compression Test of Sandstone with Different Water Saturation Under Constant Humidity Environment
In view of the low accuracy and uneven water distribution of water content in rock samples with different water saturations,a preparation method of rock samples with different water saturations and uniform distribution of water content was proposed based on the principle of osmotic technology and chemical thermodynamics.The basic principle consists of two parts:One is to control the concentration and molecular weight size of polyethylene glycol(PEG)in organic solution,so as to precisely control the matrix suction values of the solution water and water in the sample to determine the final water saturation of the sample.The other is to control the type of supersaturated solution placed in the constant humidity environment of the rock sample,so as to precisely control the chemical potentials of the component water when the total weight of the sample is stable,and the final water saturation of the sample is determined.The water saturation of rock samples prepared by this mothed are qualified samples with uniform saturation distribution.The water rationality of the method for accurately preparing rock samples with uniform water saturation distribution was also verified by nuclear magnetic resonance imaging(NMRI)experiments.Meanwhile,a device is designed independently to prepare rock samples with different saturations under constant humidity environment,and the constant strain rate compression test of sandstone under different saturation conditions was carried out by using the device.The test results show that the uniaxial compressive strength and elastic modulus of sandstone decreases with the increase of water saturation.After the peak,the post-peak stress decline slows and the brittleness of the sample decreases with the increase of water saturation.With the increase of confining pressure,the compaction stage of sandstone sample is weakened,and the deformation of the sample undergoes the process of elastic-brittle→elastic-plastic→strain hardening.The results of the study provide new methods and ideas for the accurate preparation of rock samples with different water saturations.
NETL
NSTL
万方数据
维普
