The field evaluation of pile-soil combination is a key step in the service life evaluation of pile foundation. However, due to the time-varying nature of pile-soil interaction, there is no efficient method to accurately analyze it. This paper introduces a health monitoring technique for assessing the state of pile-soil bond. The transient vibration of pile-soil coupling was measured by piezoelectric ceramic sensor. In the experiment, the different bond states of pile and soil were simulated by taking clay of different density as an example. A horizontal force is applied to the top of the pile, and the induced stress wave is detected by piezoelectric ceramic intelligent aggregate sensor embedded in the pile. At the same time, taking the artificial separation of pile-soil as an example, the binding state of pile-soil is analyzed, and the influence of different soil conditions on the pile-soil bonding characteristics is studied. An energy index for quantitative evaluation of pile-soil binding quality is proposed. Taking piles buried in two layers of soil with different densities as an example, the effects of soil with different densities on pile-soil bonding characteristics were studied. Experimental and numerical results verified the effectiveness of the proposed method. The three factors influenced the pile-soil coupling. The experimental and numerical results verified the effectiveness of the proposed approach and pave the way for an approach to directly judge whether there is separation between the pile and soil and evaluate the pile safety.

To monitor the stress state and yield capacity of H-beams across their entire service process, a real-time monitoring method based on the energy signal response of ceramic piezoelectric sensors is proposed in this paper. The method is applied to conduct loading experiments on H-beams under different load values and web heights. Then, the amplitude and energy of the piezoelectric signals under the two working conditions are compared and analyzed, and the finite element analysis results are verified. The experimental results show that the time-domain waveform energy index increases under an increase in web height or load. Taking the H-section steel member with a web height of 10 cm as an example, when the load value is less than 500 kN/m, the energy index increases (on average) by ~10.5% for every 100 kN/m load increase; when the load value exceeds 500 kN/m and is below 675 kN/m (yield load), the same load increases the energy index by ~13.4%. Meanwhile, a 1 cm average increase in web height increases the energy index by ~14.6%. The finite element simulation results indicate that the ceramic piezoelectric sensor load increases under external load increases up to the yielding load. Because the stress state at the sensor location directly determines the stress wave propagation, the critical buckling loads of H-beams can be predicted using the energy index.