Influence Of Moisture Content On Strength Of Similar Material Models

The similar material model test is the main meas of mining engineering scientific research.Strength similaruty,an important index to judge the similarity between prototype and model,it is affected by the mass ratio of the model material,the mass ratio of the cementing material and the moisture content,among which the moisture content is an important parameter.Firstly,the moisture content effect similar materials of physical and chemical reactions,secondly,the moisture content affects the strength of simile material models and it is important that influenced on the accuracy of model tests and the model similarity.Exploring the distribution characteristics of the moisture content and strength field in similar material model is of great significance for further optimizing similar material model test and improving model similarity and test accuracy.In this paper,the water transfer of similar materials and the theoretical analysis under self-drying are carried out based on the theory of water transfer,and the mechanism of the effect of water content on strength is explored;the UCS test of similar material specimens and digital image correlation(DIC)technology were carried out to analyze the influence of the moisture content on the strength of similar material specimens and on the main strain of specimens;set up a similar material model test,using the frequency domain reflectometry technology(FDR)to monitore the moisture content of similar materials during model drying,the distribution characteristics of the moisture content field in the model are obtained and deduce the strength distribution cnaracteristics of the model;compared the expected strength of the model with the actual strength of the model,the difference between them was analyzed and propose an improvement plan which use numerical calculation to verified.The research shows that the uniaxial compressive strength of the model material specimen has a negative correlation with the moisture content,it looks like a exponential function,and when the water content is between 1.6%and 2.7%,the expected mechanical strength of the model test is achieved;with the increase of the moisture content,the principal strain on the specimen surface decreases and the displacement in Y direction decrease gradually;the Kriging interpolation method was used to interpolate the model moisture content monitoring data,the error was less than 2.5%,the model moisture content data interpolation was realized;the characteristics of the model's moisture content field were roughly the same in the horizontal direction;from upper to bottom,the moisture content gradually increased;the strength field distribution characteristics of the model can be obtained by inversion,by comparing the expected strength of the model with the actual strength,it was found that there was a great difference between the two models at upper part of model;based on this,an improves maintenance scheme for the model was proposed,which was to coat the upper surface of the model to reduce the difference between the actual strength and the expected strength of the model.It provided a method reference for optimizing the model test of similar materials,improving the model similarity and testing accuracy.