System Optimization Of Large Scale Suspended High Pressure Consolidation And Preliminary Study Of High Pressure K₀ Coefficient

Experimental research on deep clay has seriously hindered the development of deep soil mechanical properties due to the low consolidation efficiency of saturated high-pressure clay.In this paper,by improving and optimizing the large-scale suspended high-pressure consolidation instrument,a sufficient number of soil samples can be prepared at one time,and the system test is used to obtain the change law of the K₀ value of the sample during the consolidation process of high-pressure soil,combined with discrete The meso research provides a basis for the subsequent high-pressure triaxial experiment.The main research contents and results are as follows:Firstly,the large-scale suspended high-pressure consolidation instrument was improved and optimized to solve a series of problems caused by the larger soil sample size,long-term loading and high stress.The loading system is improved,the resistance of the wire rope loading system is significantly reduced,the height between the upper pressure plate and the loading column is adjustable,and the problems of pre-consolidation of soil samples,pressure caps,soil samples and pressure chamber sealing and drag reduction are solved.The consolidation instrument can complete the 16MPa high-pressure consolidation loading and unloading experiment.The design improves the measurement system and realizes comprehensive and accurate measurement.The self-developed bending element shear wave velocity test system can work in high-pressure saturated clay for a long time,and the received signal is clear;the entire measurement system of the consolidation instrument is sealed and calibrated,and the sand pressure sensor is used to improve the measurement accuracy.Secondly,a high-pressure K₀ consolidation experiment was carried out using an improved consolidation instrument to verify the reliability of the system,and the nonlinear variation law of soil K₀ was obtained.Comparing the K₀coefficient of deep soil in different studies;according to the triaxial experimental results,the comparison of jaky formula and modified jaky formula to calculate the K₀ coefficient on deep soil The applicability of the modified jaky formula was found to be consistent with the experimental results.The K₀coefficient calculated by the friction angle under the consolidation pressure obtained by the triaxial compression experiment of unloading confining pressure was consistent with the experimental results.By comparing the relationship between the horizontal and vertical shear wave velocity ratio and the K₀coefficient,There is a strong positive correlation,and the K₀ coefficient changes because the soil structure has changed.Finally,the discrete element software EDEM was used to simulate the one-dimensional consolidation compression experiment of clay,and the mechanism of K₀coefficient change was analyzed from a microscopic perspective.Based on the soil properties and the experimental results,the meso parameters required for numerical simulation are calibrated;the simulation comparison of spherical particles and ellipsoidal particles shows that only irregularly shaped particles will cause the same K₀coefficients as the experimental results.The image method Statistics of the particle orientation information during the loading process show that the horizontal orientation of the particles is highly correlated with the change in the K₀ coefficient.One of the reasons for the change in the K₀ coefficient is the macroscopic performance of the horizontal orientation of the particles.The paper has 64 pictures,21 tables and 81 references.