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In current design specifications for deep excavation, the determination of safety factors against groundwater inrush only considers the self-weight effect of soil mass at the bottom. However, the shear strength and its spatial variability in a cement-solidified bottom layer also plays an important role in safety factor estimation. Based on that, in this study, the strength reduction method was introduced into reliability analysis of deep excavation engineering, and the influence of shear strength and its spatial variability of cement-solidified soil on the stability of deep excavation is studied. Furthermore, a deterministic analysis method that can equivalently consider soil uncertainty is proposed and verified.

Lead-free (1 − x)(0.8Bi0.5Na0.5TiO3–0.2SrTiO3)–xLiNbO3 (BNST–xLN, x = 0–0.08) piezoelectric ceramics were fabricated by a solid-state sintered technology. The effects of LN-doping on the structural and electrical properties of the BNST–xLN system were systematically investigated. The results of Raman spectroscopy revealed that the substitution of LN softens the phonon vibrations in the BNST–xLN system, in accordance with the remarkable reduction in the phase transition temperature (TF−R), remnant polarization (Pr), negative strain (Sneg) and piezoelectric coefficient (d33). However, the degradation of the long-range ferroelectric orders was accompanied by a significant increase in the electric field–induced strain response. At x = 0.04, a maximum unipolar strain of ~ 0.36% with a corresponding normalized strain (Smax/Emax) of ~ 600 pm/V was obtained at room temperature, which should be mainly ascribed to the reversibly electric field-induced phase transition between the ergodic relaxor and ferroelectric phases due to their comparable free energies in the two-phase coexistence region. Moreover, it was also found that the BNST–xLN system processes predominant electrostrictive behaviors with relatively high electrostrictive coefficient (Q33) and excellent temperature stability when the field-induced phase transition cannot be trigged by the applied electric field, as evidenced by a fact that the Q33 value of BNST–0.08LN ceramic keeps almost constant as high as ~ 0.028 m4/C2 in the temperature range from room temperature to 120 °C.

A nonvolatile memory structure with a high-k composite of ZnO-TiO2 as a charge-trapping dielectric was fabricated by using rf-sputtering and atomic layer deposition techniques, in which the potential of the conduction-band minimum of the composite was designed to be lower than that of Si by the use of the special energy-band offsets among Si, ZnO, and TiO2. Compared to the conduction-band minimum of Si, a relatively negative potential of the high-k composite leads to a continuous rise in the shift of the flat-band potential of the memory device except a drop at the beginning part of the time-dependent retention curve after a programming operation. The drop was attributed to the escape of trapped charges at the Si/Al2O3 interface. After extracting the contribution to the deterioration of the retention curve from the traps at the Si/Al2O3 interface, it was identified that the band alignment in a charge-trapping memory device dominated its retention behaviors.