作为工程结构的基础材料，混凝土的应力及损伤发展决定了结构的性能。应力检测是评估大型土木工程结构安全及其服役状态的关键指标。机电阻抗法（EMI）是通过压电传感器（PZT）的阻抗信息来反映主体结构状态的一种检测方法。但是，当前基于机电阻抗的应力检测技术功率低、稳定性差，无法满足实际工程需求。因此，本文拟采用数值模拟和实验相结合的方法，研究优化埋置式传感器的安装方式，以改进混凝土应力检测稳定性；同时拟开发新型探针式传感器，实现混凝土应力状态检测。本文主要研究内容如下：

（1）揭示了埋置式PZT的安装方向和界面粗糙度对混凝土应力检测灵敏度和稳定性的影响。本文使用数值模拟方法，研究埋置式传感器安装方向对混凝土应力检测的影响。研究结果发现：90°安装的埋置式传感器的灵敏度更高。另外，本文还研究了传感器-混凝土界面粗糙度对混凝土应力检测的影响。研究结果表明：粗糙PZT传感器情况下，混凝土应力检测的线性相关范围达到0.48 f_c（抗压强度），远大于光滑PZT传感器案例和其他前人的研究。

（2）设计开发了一种新型的探针式传感器。推导了探针式传感器的理论模型，研究了探针材料对传感器性能的影响，最后，提出了并联PZT探针式传感器的三种激励形式。结果表明：实心铝方探针式传感器的灵敏度高、稳定性好，在三种激励形式（弯矩激励、扭矩激励、平行力激励）下，实验验证了探针式传感器能有效监测混凝土早期水化状态。

（3）基于探针式传感器的混凝土应力状态检测技术研究。采用数值模拟方法，研究了扭矩、弯矩和平行力三种激励类型的传感器对混凝土应力方向的灵敏度（一种是荷载平行于PZT厚度方向，另一种是荷载垂直于PZT厚度方向）。研究结果表明：扭矩激励形式的探针式传感器对混凝土的应力大小的灵敏度最高；平行力激励的探针式传感器对应力方向检测的灵敏度最高。此外，扭矩激励型探针式传感器对微小损伤检测的稳定性最好。

As the fundamental material for engineering structures, the stress and damage development of concrete determine the performance of the structures. Stress detection is a key indicator for evaluating the safety and serviceability of large civil engineering structures. Electromechanical impedance (EMI) is a detection method that reflects the state of the main structure through the impedance information of piezoelectric sensors (PZT). However, the current stress detection technology based on electromechanical impedance has low power and poor stability, which cannot meet the requirements of practical engineering. Therefore, this paper proposes to use a combined approach of numerical simulation and experimentation to study the optimization of the installation method of embedded sensors in order to improve the stability of concrete stress detection. Additionally, a new probe-type sensor is intended to be developed to achieve concrete stress state detection. The main research contents of this paper are as follows:

(1) The influence of the installation direction and interface roughness of embedded PZT on the sensitivity and stability of concrete stress detection is revealed. Numerical simulation is used to study the influence of the installation direction of embedded sensors on concrete stress detection. The research results show that the sensitivity is higher for sensors installed at 90°. Furthermore, the influence of the sensor-concrete interface roughness on concrete stress detection is also studied. The research results indicate that under the condition of a rough PZT sensor, the linear correlation range of concrete stress detection reaches 0.48 fc (compressive strength), which is much higher than the case of a smooth PZT sensor and previous studies.

(2) A new probe-type sensor is designed and developed. The theoretical model of the probe-type sensor is derived, and the influence of probe material on sensor performance is studied. Finally, three excitation forms of parallel PZT probe-type sensors are proposed. The results show that the solid aluminum square probe-type sensor has high sensitivity and good stability. Experimental verification under three excitation forms (bending moment excitation, torsional excitation, and parallel force excitation) confirms that the probe-type sensor can effectively monitor the early hydration state of concrete.

(3) Research on concrete stress state detection technology based on probe-type sensors. Using numerical simulation, the sensitivity of sensors of three excitation types (torsion, bending moment, and parallel force) to the stress direction of concrete is studied (one type is the load parallel to the thickness direction of PZT, and the other type is the load perpendicular to the thickness direction of PZT). The research results show that the probe-type sensor with torsional excitation has the highest sensitivity to the magnitude of concrete stress, while the probe-type sensor with parallel force excitation has the highest sensitivity for stress direction detection. In addition, the probe-type sensor with torsional excitation exhibits the best stability for detecting small-scale damage.

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