基于应变软化的岩土工程单元安全度评价方法研究

A STUDY ON EVALUATION METHOD OF GEOTECHNICAL ENGINEERING ZONE SAFETY DEGREE BASED ON STRAIN SOFTENING

针对大多已有岩土工程局部安全评价方法未考虑拉伸破坏和屈服、破坏阶段的问题,对围岩的局部安全评价方法进行了相应的改进。基于Mohr-Coulomb屈服准则和应变软化模型建立了单元安全度的评价方法和新的定义,综合考虑剪切和拉伸破坏模式,定义一个统一的变量ZSD来表征和量化岩土体单元从弹性、屈服到破坏的安全程度,实现复杂应力状态下岩土体渐进破坏过程的局部安全性定量评价。推导了ZSD的各阶段表达公式,利用FISH语言在FLAC^(3D)平台编写程序。通过相应的实例和工程进行了ZSD计算,验证了该方法的正确性与有效性。该方法具有参数表达简单,易于在程序中实现,可通过ZSD所在值域判断单元所处的状态,可直观揭示岩土体渐进破坏过程等诸多优点。该方法为分析和预测岩土工程中危险区域的演化和描述渐进破坏过程提供了有效的手段。

In view of the fact that the problems encountered in the stage of tensile failure, yield and failure stage are not considered in most existing local safety evaluation methods of geotechnical engineering, the local safety evaluation method of surrounding rock has been improved accordingly. The new evaluation method and new definition of geotechnical engineering zone safety degree were established based on strain softening model and Mohr-Coulomb yield criterion. It is defined by a uniform variable ZSD （Zone Safety Degree）synthetically considering shear and tension pattern, describing the safety degree of geotechnical body element from elastic stage, yield stage to failure stage, realizing the local safety quantitative evaluation with complex stress state and progressive failure progress. The ZSD expression formulas at different stages are derived, and the program by FISH language based on FLAC 3D platform is compiled. The corresponding examples and engineering are calculated, and the accuracy and efficiency of the ZSD method are verified. This method is simple in parameter expression and easy to be implemented in the program. It can judge the state of the zone in the range of ZSD and directly reveal the progressive failure process of rock and soil mass. This method provides an effective means for the analysis and prediction of the evolution of hazardous areas in geotechnical engineering and the description of the progressive failure process.