软岩筑坝堆石料劣化特性研究

Degradation Behavior of Soft Rock Filling Material for Dam Construction

为全面了解软岩料的工程性质,以软岩筑坝堆石料为对象,针对其劣化前后的力学特性与设计参数开展了室内试验研究。基于不同围压与压实度条件下的试验研究,分析了堆石料强度与变形的劣化规律,建立了压实度与归一化强度、归一化变形模量的关系,提出了堆石料的压实度控制指标。进一步结合水下休止角试验,针对堆石料的非线性强度尤其是低应力强度特性进行了分析。结果表明:劣化作用引起体积应变减小,劣化作用对模量的影响远大于对强度的影响;96%的压实度对于软岩填料而言较为合理,既保证了归一化的强度>0.9,归一化的变形模量>0.8,也确保了压实机械的效率;可采用击实样水下休止角试验来获得低应力状态下软岩填料强度参数,用三轴试验来获得的中高应力状态下软岩填料的强度得到软岩填料的非线性强度。研究成果可为正确评价软岩堆石坝的应力、变形规律和指导工程实践提供依据。

In this article,the mechanical behavior of soft rock filling material for dam construction before and after degradation is investigated through laboratory tests at different consolidation pressures and compaction degrees. The degradation in strength and deformation characteristics of the rockfill material is analyzed. The relationship between degree of compaction and normalized strength,and the relationship between degree of compaction and normalized deformation modulus are built respectively. The controlling degree of compaction is also given for construction. Furthermore,according to results from underwater test of repose angle,the nonlinear strength,in particular,the strength at low stress state is studied. Research findings conclude that the degradation leads to the decline of volume strain,and poses larger impact on deformation modulus than strength; a 96% degree of compaction is reasonable forsoft rock filling material as it ensures a normalized strength larger than 0.9 and normalized deformation modulus larger than 0.8,and guarantees the compaction efficiency as well. Moreover,the strength parameters of soft rock filling material can be acquired from underwater repose angle test on compacted samples; and the nonlinear strength can be obtained through triaxial test. The research findings can be utilized to evaluating the stress-strain rules of rockfill dam built in soft rock and to providing guidance for dam construction.