陕西省建研所选定“回弹——超声(混凝土声速或砂浆声速)”综合法作为主要研究对象,通过大量室内试验与省内、外工程实测,总结提出了采用多元函数综合法必须遵守的四个基本原则,即单一法的仪器性能、测试技术和测定误差都应满足规定的要求;在已查明单一法测强影响因素的基础 The “Rebound-Ultrasonic (Sonic Acoustic Velocity or Mortar Acoustic Velocity)” synthesis method was selected as the main research object by the Shaanxi Institute of Research and Development. Through a large number of laboratory tests and actual surveys within and outside the province, it was concluded that a multivariate function synthesis method must be followed. The four basic principles, namely the single-method instrument performance, test technology, and measurement error, should all meet the specified requirements; the basis for determining the influencing factors of single-method strengths has been identified.