The application of prestressed pipe piles, like any other pile type, has its limitations. Certain engineering geological conditions are unsuitable for prestressed pipe piles. There are mainly four such conditions:
　　(1) Strata with abundant boulders and obstacles are unsuitable for application.
　　(2) When hard interlayers are present, application is unsuitable or should be used with caution.
　　(3) Limestone areas are unsuitable for application.
　　(4) Strata that abruptly change from soft to extremely hard are unsuitable for application.