To explore the feasibility of cemented paste backfill with phosphogypsum (PG), bleeding water and rheological tests (slump and on-site pipeline loop tests) were performed with PG backfill slurry (PGBS). In the bleeding water test, the PGBS concentration with minimal bleeding water was measured between 60.87 and 67.61%; in the rheological slump test, values of 61 to 68% were determined for the on-site pipeline loop test. The rheological pipeline loop test demonstrated that the resistance coefficient is lowest when the concentration is no higher than 65%. Through industrial experiments, PG slurry with a concentration of 64%–65% backfill was successfully applied to the goaf. The experimental results demonstrate that PGBS with characteristics of “less bleeding water” and “improved pumpability” is obtained when its concentration is between 61 and 65%. Paste-like PG slurry was proven to be optimal for cemented PG backfilling technology.

This study is aiming at the problems of slow collision detection speed of bounding box, low efficiency of triangle intersection detection, and triangulation in regions where complex intersecting lines are segmented that exist in Boolean operation of triangular mesh model in underground space engineering. The orientation calculation method of underground space engineering is put forward, and the precise definition of bounding box is realized. A simple method to realize the fast intersection detection algorithm between triangles is presented, the process of transforming the projection of intersecting lines into scalar and then judging is eliminated, and the efficiency of triangle intersection detection is improved. On the basis of Delaunay triangulation robust algorithm, numbering method of intersection position is improved. Central axis region division method and hierarchical subdivision triangulation method are proposed, which can divide all the regions of mixed complex intersections in one traversal. A subdivision triangulation method by comparing the cosine value of internal tension angle is proposed, and the subdivision triangulation of polygon is optimized. The feasibility of the algorithm is verified by practical engineering application.