Fracture Analysis of Compacted Clay Soil Beams with Offset Notches Based on Three-Point Bending Test: Experimental Characterization and Numerical Simulation

The design and performance of tillage components such as subsoiler are generally characterized by the fracture features of soil mass in agricultural engineering, thus making the improvements of those tillage tools challenging due to the fact that the soil fracture mechanisms cannot be accurately explored and implemented. To alleviate this issue, in this paper, a physical three-point bending (TPB) test is conducted for investigating the fractural and fragmental characteristics of the compacted clay beams (CCB) with offset notches under the framework of mixed-mode I + II fracture, and the crack initiation as well as its propagation of the CCB is observed and fractural mechanisms of the CCB are discussed. Meanwhile, numerical simulation is also conducted utilizing two finite element methods, i.e., the extended finite element method (XFEM) and the combined finite-discrete element method (FDEM), for the CCB under three typical scenarios with notch offset ratios C = 0, C = 0.375, and C = 0.625, respectively. The authenticity and availability of both experimental test and numerical simulation are validated correspondingly. Results indicate the following: (1) The average peak load, the distance between the terminal crack point and the center line of the CCB, and the average displacement will be increased with increases of the offset ratio, while initial crack angle will be decreased with increases of the offset ratio. (2) The initial crack will be extended from the bottom center of the CCB rather than the offset notch when the offset ratio is higher than 0.717. (3) The crack propagation and its mechanical properties (e.g., load-displacement curves) predicted by numerical simulation match well with those obtained from the physical test.

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