CAREER: Understanding and Predicting the Dynamic Behavior of Mine Tailings Dam Materials

在美国的1 555个尾矿结构中，约有三分之一具有高危险性，如果发生故障，将导致人员伤亡。在过去的40年里，全世界大约有15座尾矿坝由于地震震动造成的细粒垃圾液化而失败。分析土壤抗液化性的方法是存在的，但是尾矿，包括粗的和细的垃圾，本质上不同于土壤。人们已经做出了一些努力来理解和预测尾矿材料的循环特性、抗液化性和抗剪强度，但是缺乏对尾矿动态特性评估的全面理解和统一方法，部分原因是尾矿坝结构的测试和取样存在困难。这项工作将集中在实验室和现场测试，以了解和预测矿山尾矿坝材料的动态行为。实验室共振柱试验将用于测量剪切模量、材料阻尼和剪切应变之间的关系。将使用实验室循环三轴试验来确定抗液化性，即循环阻力比（CRR）。将研究孔隙比、细粒含量、龄期、含水量、孔隙压力和围压等参数对材料动力特性的影响。将采取特别措施回收样本进行实验室测试，包括固定活塞取样，并在蓄水池内建造工作垫，以减少现场设备的表面压力。将进行现场标准贯入试验（SPT）、锥形贯入仪试验（CPT）和地震试验，并将开发使用超载校正的SPT击数（（N1）60）、CPT锥尖阻力（qc1）和剪切波速度（vs1）的方法，以评估原位抗液化性。将现场十字板剪切数据与CPT数据相关联，以开发一种用于稳定性分析的细粒垃圾峰值和剩余不排水剪切强度的估算方法。通过测量这些材料的动态特性，将采用用于土壤的方法，包括现场方法。地球科学家将能够更好地预测尾矿坝对动态激励的反应，这将导致在循环应力比（CSR）方面对地震引起的负荷的估计得到改进。他们将能够更好地预测地震引起的超孔隙压力和液化引起的有效应力降低和强度降低，这将使他们能够更准确地评估地震期间和震后条件下大坝的稳定性。

Approximately one-third of the 1,555 tailings structures in the United States are high-hazard potential, where failure would result in loss of human life. Over the past 40 years, approximately 15 tailings dams have failed worldwide as a result of liquefaction of fine refuse due to earthquake shaking. Methods to analyze liquefaction resistance exist for soil, but mine tailings, including coarse and fine refuse, are inherently different than soil. Some efforts have been made towards understanding and predicting the cyclic behavior, liquefaction resistance, and shear strength of tailings materials, but a comprehensive understanding and unified approach towards the assessment of the dynamic behavior of mine tailings is lacking, partly due to the difficulties involved with testing and sampling of tailings dam structures. This work will focus on laboratory and field testing to understand and predict the dynamic behavior of mine tailings dam materials. Laboratory resonant column testing will be used to measure the relationship between shear modulus, material damping, and shear strain. Laboratory cyclic triaxial testing will be used to determine liquefaction resistance in terms of the cyclic resistance ratio (CRR). The effect of parameters such as void ratio, fines content, age, water content, pore pressure and confining stress on the dynamic behavior of the materials will be investigated. Special measures will be taken to recover specimens for laboratory testing, including fixed piston sampling, and construction of work pads in the impoundments to reduce surface pressures of field equipment. Field standard penetration testing (SPT), cone penetrometer testing (CPT), and seismic testing will be performed, and methods will be developed to use overburden-corrected SPT blow count ((N1)60), CPT cone tip resistance (qc1), and shear wave velocity (vs1), to assess in situ liquefaction resistance. In situ vane shear data will be correlated with CPT data to develop a method to estimate peak and residual undrained shear strength of fine refuse for stability analyses.By measuring the dynamic behavior of these materials, methods used for soils will be adapted, including in situ methods. Geoscientists will be able to better predict the response of tailings dams to dynamic excitation, which will result in improved estimates for earthquake-induced loading in terms of cyclic stress ratio (CSR). They will be able to better predict reductions in effective stress and reductions in strength due to earthquake-induced excess pore pressures and liquefaction, which will allow them to more accurately assess the stability of dams during earthquakes and under post-earthquake conditions.