Experimental study on the mechanical properties of Yellow River floodplain silt during shield construction
Description
The mechanical properties and failure strength of Yellow River floodplain silt were comprehensively analyzed under varying stress paths encountered during shield construction. Undrained plane strain and conventional triaxial tests were conducted at quantify different initial stress ratios and consolidation pressures using true triaxial and GDS triaxial apparatuses. The results of the plane strain tests were analyzed in detail, and the plane strain strength criterion was modified to improve its suitability for Yellow River floodplain silt. The stress-strain curve indicated strain hardening for different stress paths, and the shear strength increased with the confining pressure and the initial stress ratio K. The degree of influence depended on the stress path. The failure strain of the sample was much lower during unloading than during loading. The strength parameters were significantly lower for lateral unloading than vertical loading, and the initial stress ratio had the largest effect on increasing cohesion. In contrast, the impact on the internal friction angle was negligible. Plane strain tests determined an intermediate principal stress ratio at failure of 0.15-0.21.A newly established relationship between cohesion and the initial stress ratio K, implemented within the modified Lade-Duncan criterion, enabled accurate prediction of the silt's loading/unloading strength.
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Institutions
- Zhengzhou University