A Study On The Measurement Of Soil Resistivity By VdP Method Considering Effect Of Sample Thickness

Soil resistivity is an important means to evaluate the engineering properties of soil.Accurate measurement of soil resistivity is particularly important for both theoretical and engineering applications.The vdP method is one of the methods used by many scholars to measure the electrical resistivity of soils.However,there is little research on the resistivity of columnar soils,especially triaxial sample.In addition,there are more or less defects in soil resistivity testing instruments and methods at present,such as the shape requirement of the tested sample,the fixed position of the test electrode,the limitation of the testing scope,the low accuracy and the influence of the thickness effect of the sample on the resistivity measurement accuracy by vdP method.Based on this,Testing the columnar soil resistivity based on the principle of vdP method.On the one hand,combined with the soil resistivity test system independently developed by the laboratory,the indoor test is conducted to influence the resistivity of the test column soil;on the other hand,numerical calculation is used to explore how to eliminate the thickness effect and reduce the measurement error so as to measure the resistivity of the columnar soil more accurately.The main content and test results are as follows:(1)Based on vdP method,the columnar soil was taken as the research object,and the corresponding experimental scheme was developed to study the influence of titanium electrode size,electrode position and sample thickness on the soil resistivity of the method.By mastering the law of the influence of these sensitive factors on the method.(2)Two types of electrode contact models were established: point and sheet electrode contact model.The accuracy curve of the soil resistivity measured by the vdP method was obtained by the point electrode contact model analysis,that is,when the ratio of soil thickness to diameter was in the range of 0.3,the method can accurately measure the soil resistivity and has nothing to do with the diameter of the soil sample.The regular curves of the electrode size and the thickness of the soil sample to the measured resistivity were obtained.(3)To solve the problem of the thickness d in vdP,the method has been breached to the limit of the thickness of the soil sample,and also guaranteed the resistivity of the soil beyond the thickness of the test.Based on the data of the triaxial soil sample resistivity of the triaxial electrode test,the vdP method,which is based on the thickness effect,has a more extensive applicability and engineering application.