Abstract
The unfrozen water content(UWC)of rocks at low temperature is an important index for evaluating the stability of the rock engineering in cold regions and artificial freezing engineering.This study addresses a new method to estimate the UWC of saturated sandstones at low temperature by using the ultrasonic velocity.Ultrasonic velocity variations can be divided into the normal temperature stage(20 to 0℃),quick phase transition stage(0 to -5℃)and slow phase transition stage(-5 to -25℃).Most increment of ultrasonic velocity is completed in the quick phase transition stage and then turns to be almost a con-stant in the slow phase transition stage.In addition,the UWC is also measured by using nuclear magnetic resonance(NMR)technology.It is validated that the ultrasonic velocity and UWC have a similar change law against freezing and thawing temperatures.The WE(weighted equation)model is appropriate to es-timate the UWC of saturated sandstones,in which the parameters have been accurately determined rather than by data fitting.In addition,a linear relationship between UWC and ultrasonic velocity is built based on pore ice crystallization theory.It is evidenced that this linear function can be adopted to esti-mate the UWC at any freezing temperature by using P-wave velocity,which is simple,practical,and ac-curate enough compared with the WE model.
基金项目
National Natural Science Foundation of China(42072300)
National Natural Science Foundation of China(41702291)
Project of Natural Science Foundation of Hubei Province(2021CFA094)
NETL
NSTL
维普
万方数据