Abstract：The technologies of geographic information system(GIS) and spatial information provide a new method for solving complex problem in geotechnical engineering，where the technology of model construction for strata and caverns in three-dimensional space is a key issue. Analysis of developing spatial three-dimensional strata model will make it possible for GIS to be successfully applied to geotechnical engineering. However，there are few references related to this subject at present. Based on a typical slope project in Longtan Hydropower Station，the technique for model construction of three-dimensional grid strata model which consists of multi-variant information such as monitoring facilities，construction measures and faults，is introduced. In addition，some spatial analysis algorithms such as generation of simple strata cross-section，intersection between strata and three- dimensional objects，hybrid sectional algorithm between strata and cavern，spatial calculation for area and capacity in arbitrary zone are discussed. The proposed technology will give some useful references to the continuous research on this subject.
