高温处理后巴丹托鲁水电站凝灰岩的三轴压缩力学特性与损伤演化规律

Mechanical properties and damage evolution rule of tuff at Badantoru hydropower station under triaxial compression after high temperature treatment

以印度尼西亚巴丹托鲁水电站为工程背景,对坝址处凝灰岩分别开展100,200和300℃高温下的三轴压缩试验研究。针对其应力-应变曲线、体积应变特性、破坏及失稳形式展开分析,结合脆性指数分析凝灰岩的脆-延性转化特征,基于Pearson相关系数探讨温度、围压与不同特征参数的相关性。结合应力-应变曲线分析凝灰岩的弹性应变能及耗散能的演变过程,并基于累积耗散能定义损伤变量。研究结果表明:高温及高围压能够提升凝灰岩的延性。凝灰岩破裂面数量随温度升高而增多,不同围压下岩样由脆性张拉破坏向剪切破坏转变,失稳形式由突发型失稳向渐进型失稳过渡。凝灰岩的峰值应力、弹性模量、泊松比、膨胀角、内摩擦角及黏聚力等参数均随温度及围压的变化呈现出一定的变化规律。凝灰岩的能量演化曲线能够较好地反映不同阶段的裂缝发育情况,损伤因子演化曲线具有三阶段特性,与试样突发型失稳的破坏特征一致。

Based on the engineering background of Batantoru hydropower station in Indonesia,the triaxial compression tests of tuff at the dam site at high temperatures of 100,200 and 300℃were carried out.The stressstrain curve,volumetric strain characteristics,failure and instability forms were analyzed.Combined with the brittle index,the brittle-ductile transformation characteristics of tuff were analyzed.Based on Pearson correlation coefficient,the correlation between temperature,confining pressure and different characteristic parameters was discussed.Combined with the stress-strain curve,the evolution process of elastic strain energy and dissipated energy of tuff was analyzed,and the damage variable was defined based on the accumulated dissipated energy.The results show that high temperature treatments and high confining pressure can improve ductility of tuff.The number of fracture surfaces of tuff increases with the increase of temperature,the failure mode of tuff changes from brittle-tensile failure to shear failure under different confining pressures,and the instability form changes from sudden instability to gradual instability.The peak stress,elastic modulus,Poisson's ratio,expansion angle,internal friction angle and cohesion of tuff all show a certain change rule with the change of temperature and confining pressure.The energy evolution curve of tuff can reflect the crack development activities in different stages,and the damage factor evolution curve has three-stage characteristics,which is consistent with the failure characteristics of sudden instability of the specimen.