answer each question by giving details

1) What are the three aspects that define soil as engineering material? Elaborate.

2) Why shear strength is essential in soil mechanics? Why not compression strength or tension strength?

3) By navigating the Internet, identify a major national or international conference that has taken place or will take place this year with focus on geotechnical engineering. Which organization was or is mostly responsible for organizing the conference? Provide examples of topics that were or will be discussed in the conference.

4) Why soil-particle size and shape are important?