[Objective] This study was to evaluate the ecological suitability of agricultural land in western Jilin Province, with the aim to provide basis for the effective application of agricultural resources and the structural adjustment of land use. [Method] The evaluation index system was constructed based on fuzzy mathematic method according to the principles of systematic, dominant, effectiveness and feasibility; based on law of tolerance, reasonable evaluation criteria were determined according to the ecological amplitude of crops; based on GIS processing, the initial data completed the mathematical operation by using the VBA program in Excel. [Result] The area of agricultural land grade I was 5 512 km2, grade II of 25 985 km2, grade Ill of 7 907 km2, and area of land not suitable for agriculture was 6 312 km2. According to the evaluation results, the key areas for land use adjustment were Zhenlai County, Da＇an County, Tongyu County and western Changling County. The directions of land use adjustment included improving irrigation and drainage conditions, governing land salinization and conversion of cropland to forest and grassland. [Conclusion] This study provided basis for the effective application of agricultural resources and ecological environment construction in western Jilin Province.
Rock-quality designation(RQD) plays a significant role in rock mass analysis and is an important parameter in geotechnical and geological engineering.However,the RQD variation with scanline length has not yet been comprehensively considered in RQD.In this study,three-dimensional fracture network modeling was used to simulate actual rock mass,and numerous scanlines were set in the fracture network for investigation on RQD variation.Models and equations(i.e.,models A-A,N-N,and A-A-S,as well as the Priest-Hudson and Sen-Kazi equations) were summarized for the study.A corrected equation was proposed to eliminate the errors from using the Priest-Hudson and Sen-Kazi equations.In addition,inhomogeneous and anisotropic features were investigated,and the optimal thresholds for RQD calculation were determined,which varied with the study orientation and rock mass feature.When the inhomogeneity was studied in the x direction,the optimal threshold was found to be 4 m.When anisotropy was studied,the optimal threshold was found to be 3 m.
