| The near-surface is the most complex part of underground medium.It is of great significance to study the changing patterns of waves in shallow stratum to develop underground space.Static cone penetration test is widely used in geological survey.Previous studies have established a one-variable empirical relation between static cone penetration test and compression modulus,revealing certain regional limitations.At the same time,the collected data have not been fully utilized,and the relation between cone resistance and soil wave pattern has not been set.In geophysical exploration,PS logging is usually used to obtain the body wave velocity distribution of soil layer.However,the instrument response of shallow soil layer is obviously different from that of rock medium,hence impossible to obtain high-resolution exploration results.Therefore,the CPT method is applied to near surface.In order to break through the regional limitations,this research proposes the technique of predicting wave patterns in soil medium based on the cone resistance of CPT.This study deduces and summarizes the corresponding body wave formula of soil in single-phase,two-phase and three-phase states.With the field data,it makes regression analysis on the elastic modulus,cone resistance and soil depth in different depths,raising binary-variable linear equation.Finally,through the soil wave formula,it obtains the wave velocity pattern based on the original value of static cone penetration test,and verifies the accuracy of the theoretical formula.According to the application experience of static cone penetration records,the formulas are applied to the near-surface environment,including horizon calibration,soil liquefaction judgment,foundation bearing capacity.The study proves that the method is feasible and of practical significance. |
