Experimental Research On Expansive Force Of Anhydrite Rock And Its Testing Method

Taking the anhydrite rock exposed in a tunnel in Shanxi as the research object,the basic properties related to the expansion of the existing anhydrite rock are collected and sorted out,and the expansion mechanism of the anhydrite rock is studied.Through conducting tests method of standard and analyzing the test results,some problems of the existing test methods were found.Proposed a method which can measure expansion force of anhydrite in short time.The main research results are as follows:1.Based on the collection of existing engineering studies and related chemical theories,the basic properties of anhydrite rock related to expansion after its water absorption are summarized,and the relationship between the basic properties and the hydration and expansion process is analyzed.The difference in swelling phenomena and mechanism between argillaceous rock and anhydrite rock is compared.2.Based on the experimental research of the swelling force test method in the Code for Rock Test of Railway Engineering,the analysis shows that this method may not be fully applicable to measuring the swelling force of anhydrite rock.3.Designed an improved rock triaxial expansion force measuring instrument.The test principle of the instrument adopts the idea of strictly controlling the deformation of the sample,avoiding the possible negative impact when uses the existing method on the test results.4.Based on the existing method which drying anhydrite rock samples with high temperature to speed up the test,through theoretical analysis to find out the impact of hightemperature drying on anhydrite rock.Through conducting experiment,the relationship curve between different drying temperatures and the expansion force measured in the test is obtained,which proved the expansion force measured by this high-temperature drying method is not the actual potential expansion force of anhydrite rock.5.Based on the above research,a test and data processing method that can calculate the potential expansion force of anhydrite rock in a short time is proposed,while subsequent test results verified the feasibility of the method.Some reference opinions for accurate measurement of anhydrite rock expansion force and subsequent research directions are provided.