China has numerous deep engineering projects situated in the mountainous regions of the western areas， characterized by extremely complex topography and geological conditions marked by high altitude， great depth， high stress， high water pressure， high ground temperature， and significant hydraulic head differences， making refined geological investigations imperative. Over the past decade， relying on the deep engineering exploration practices of a major hydropower project and multiple large-scale pumped storage projects in the western region， the PowerChina Chengdu Engineering Corporation Limited， in collaboration with several universities and research institutions， has conducted technological breakthroughs in areas such as directional drilling for deep engineering and wire-line coring in deep overburden layers. Multiple innovative achievements have been realized， providing the foundation and basis for compiling three technical specifications in the field of engineering investigation： Technical Specification for Directional Drilling in Engineering Investigation， Technical Specification for Deep Hole Drilling in Engineering Investigation ， and Technical Specification for Wire-line Coring Drilling in Overburden Layers. These three specifications were officially released on January 25， 2025， and became effective from March 1， 2025. The compilation and release of these three specifications in the engineering investigation field will promote technological advancements in deep exploration for major engineering projects.