A practice of cemented backfill technology with ultra-fine tailings in a gold mine was comprehensively presented, and a series of tests were conducted in accordance with the peculiar properties of ultra-fine tailings and the mining technology conditions. The test results show that, the tailings from Shuiyindong Gold Mine have a great grinding fineness, with the average particle diameter 22.03 μm, in which the ultra-fine particles with the diameter below 20 μm occupying 66.13%. The analysis results of chemical components of tailings indicate that the content of SiO is relatively low, i.e., 33.08%, but the total content of CaO, MgO and AlO is relatively high i.e., 36.5%. After the settlement of 4-6 h, the tailing slurry with the initial concentration of 40% has the maximum settling concentration of 54.692%, and the corresponding maximum settling unit weight is 1.497 g/cm. During the field application, the ultra-fine tailings and PC32.5 cement were mixed with the cement-tailings ratios of 1:3-1:8, and the slurry concentration of 50 wt% was prepared. Using the slurry pump, the prepared cemented backfill slurries flowed into the goaf, and then the strength of the cemented backfill body met the mining technique requirements in Shuiyindong Gold Mine, where the ore body has a smooth occurrence, with the average thickness of approximately 2 m and the inclination angle ranging from 5 to 10°.Copyright © 2017 Elsevier Ltd. All rights reserved.

在将尾矿坝剖面概化为一基本剖面的基础上,探讨了坝体内各层渗透系数之比、尾矿堆坝干滩长度、尾矿堆坝上游坡度、下游坡度、出口附近渗透系数降低等因素对尾矿坝浸润线的特殊影响,提出尾矿坝前期设计中应综合考虑能够降低浸润线的各因素,以设计出更合适的坝型、排渗设施及其合理尺寸.笔者对影响尾矿坝渗流场的因素分析和研究的结果可为尾矿坝设计、施工及尾矿坝的管理提供参考.

渗透系数的空间变异性是影响渗流场不确定性的重要因素。将渗透系数作为各向同性对数正态平稳随机场，通过数值模拟研究渗透系数空间相关性对渗流场统计特征的影响。选取了3种具有代表性的相关函数模型，即指数模型、高斯模型和球状模型，分别以渗透系数的相关距离和变异系数为变化因子对水头方差作敏感性分析。结果表明，渗透系数相关函数模型的选取、相关距离和变异系数的取值对水头方差具有较大影响。

The spatial variability of permeability coefficient is a main cause for the uncertainty of seepage field. With the basis that the permeability coefficient is an isotropic random field which follows lognormal distribution, the influence of the spatial correlation of permeability on the statistics of seepage field is researched by stochastic numerical modeling. Three representative correlation functions, such as exponential, gaussian and spheric models, are adopted. The sensitivity analyses to variance of hydraulic head for above three models are conducted respectively with correlation distance and variation coefficient of permeability as variable factors. The results show that the choice of correlation model and the value of correlation distance and variation coefficient have an important impact on variance of hydraulic head.

The permeability coefficient of tailings in tailings ponds, which can affect the release and migration of heavy metals in tailings, also affects the stability of dams by affecting the variation of the height of the saturation line. In this paper, tailings at different levels in a tailings pond were taken as research objects to measure the particle size and permeability coefficient of the tailings. At the same time, CT scanning technology and three-dimensional reconstruction were used to establish the three-dimensional model of the tailings, and the permeability coefficient of the tailings was analyzed from a mesostructural point of view. The results show the following: (1) The particle size of the tailings in the tailings pond decreased rapidly with the increase of distance from the discharge port. When the distance exceeded 8 m, a sudden change occurred, and the decreasing trend obviously slowed down. The particle size of tailings decreased, the compactness increased, and the permeability coefficient decreased gradually. (2) Statistics and analysis of the mesostructure affecting the permeability coefficient of tailings: the error between the calculated value and the measured value of the particle size and porosity of the three-dimensional reconstruction model was small, which proved that the model had high reliability. The porosity, sphericity, and particle size of the tailings were consistent and decreased with the increase of distance from the discharge port. The number of pore branches and nodes of the tailings increased with the increase of the distance from the discharge port, while the average radius and length of the pores decreased. The fragmentation index can characterize the pore channel connectivity of the tailings, which has a high negative linear correlation with the number of pore branches and a positive quadratic curve correlation with the average branch length of the pores. (3) Based on the Kozeny-Carman equation and data regression analysis method and combined with the results of permeability coefficient measurements, the fragmentation index was introduced into the Kozeny-Carman equation. Also, a modified model for calculating the permeability coefficient of the tailings was established based on the mesostructure parameters. By comparing the measured values of the tailings' permeability coefficient, the error range was 1.91-13.24%. The research results have important theoretical significance for the prevention and control of heavy metal pollution and the stability of tailings ponds.© 2022 The Authors. Published by American Chemical Society.

离心模拟技术正式登上岩土工程舞台已有半个多世纪了。由于它具有真实地再现工程实际应力水平的独特优点，因此成为岩土工程性状模拟的重要手段，具有不可替代的地位。首先介绍了离心模拟技术的原理和优缺点、主要用途，以及发展简史。然后，较具体地叙述了我国近年在边坡和土石坝工程、基坑和地下工程、软基工程、加筋挡墙、抗震工程、海洋与港口工程等常见的土工工程中若干成功的应用实例，同时也介绍了利用离心机解决岩土工程研究中疑难课题的一些新鲜经验，如深水抛填料密度、冻土工程、爆炸与地震海啸模拟、污染物的迁移、岩石力学研究等。最后对离心模拟技术的进一步发展作了展望。

Centrifugal modeling technology has been applied to geotechnical engineering for more than half a century. It has been an important and indispensible means to simulate the geotechnical behavior because it can reflect the actual stress level. In this paper, the principle, advantages and deficiencies, as well as the main applications and history of centrifugal modeling technology are reviewed. Successful application examples in common engineering structures including soil slope, earth rock dam, deep foundation pit, underground structure, soft foundation treatment, reinforced structure with geosynthetics, antiseismic engineering, ocean platform, and harbor engineering are described in details. Moreover, experiences of using centrifuge in solving geotechnical research problems are presented, such as the dumping density of weathered sand in deep water, frozen soil engineering, blasting and earthquake and tsunami simulation, pollutant transport, and rock mechanics. Finally, the future development of centrifuge in China is also presented.

Due to the presence of fine-grained interlayer structures (usually called lenticles), the stabilities of tailings dams deteriorate. In this study, the strength and deformation of tailing samples containing fine-grained interlayers were studied by undrained tests. Based on the Coulomb theory, the slip mechanism of tailing samples was investigated. The results indicate that the stress-strain relationship of the samples that contain interlayers of large dip angles (i.e., 45 degrees or 60 degrees) is typical strain softening. The stress-strain relationship of the samples, with the interlayers dipping with small angles (i.e., 0 degrees or 15 degrees), is strain hardening. The mechanical parameters, e.g., shear strength, internal friction angle and cohesion, decrease with the increase in the dip angle of the interlayer. In tests, three different deformation patterns, i.e., bulging, slip and composite deformation, were observed from the samples with interlayers of small, large and medium dip angles, respectively (the medium dip angle is 30 degrees). The slip occurred along the interlayer plane of the samples. When the angle of the interlayer is near 60 degrees, the strength and deformation of the samples are controlled by the fine-grained interlayer. The findings of this study can provide reference for the stability evaluation of anisotropic tailing dams and other similar structures.