$-----------**$ geotechnical investigations contribute to the design and construction of civil infrastructure? Explore the significance of soil testing in determining soil properties and assessing site suitability. Discuss common methods used in geotechnical exploration and their applications in different soil types. Analyze the role of geotechnical data in designing foundations, slopes, and retaining structures. Furthermore, examine how geotechnical findings influence construction techniques and risk management strategies in civil engineering projects."$**+$