Soil Cracking Improved Model With Spatial Correlation Length And Simulated Analysis

Cracking are widespread in nature that affect a range of soil properties.Characterization of crack networks in clay soils is needed to quantify the soil-plant relationships.This paper presents a numerical model of the desiccation cracking process.In order to explore the development law and mechanism of dry shrinkage fissure on farmland soil surface under the influence of water evaporation,the soil cracking model based on Hookean’s law is improved.The correlation length concept was used to reflect the spatial continuity of the soil and to construct a critical strain random field to simulate the dynamic cracking of soil.Three morphological parameters,which are indicators of quantitative crack analysis(i.e.,Minkowski area densities,length densities,and Euler number)were used to describe the spatial distribution and morphological connectivity of cracks.After calculated:(1)The determination coefficients of the area,length,and Euler density of simulated and experimental images are all greater than 50%,the mean square root error RMSE is satisfied with less than 20%,the deviation BIAS and the average relative error MRE are smaller enough,and the consistency index IA is close to 1.It is shown that the improved model simulation results are satisfaction.(2)Then,only change the "random seed number" and achieve strain thresholds with the random field,and take it into the soil cracking model to simulated.Founding that the area density and length density of the fracture well reflect the change rule from the initial stage off fracture development to the stable stage,and the change trend is basically the same.It shows that the concept of correlation length added is corrected.(3)In order to reflect the advantages and disadvantages of the improved model and the original model simulation results,the model simulation results that have not been introduced into the relevant length are compared with the improved model simulation results.Among them,the improved model’s determination coefficient R2 and the consistency index IA numerical results are closer to 1 than the model simulation without considering the relevant length,indicating that the improved model better reflects the dynamic cracking process of the crack.(4)In chapter 5 of the paper,the main parameters of the improved model are analyzed.By changing the values of the variance and mean value and spatial correlation length of the random field,the influence of the model on the results of simulated cracking is analyzed.The results show that:when the correlation length is in the range of 10 cm and the variance is greater than 0.2,the larger the correlation length,the smaller the variance,and the more uniform the soil cracking.