柔性注压锚杆锚固段阻抗摩擦应力分布规律模拟研究

针对柔性注压锚杆解析及实验比较困难,采用有限元方法,模拟研究其锚固段阻抗摩擦应力的分布规律。数值模拟显示:沿锚杆环向呈近似正弦或余弦函数的循环分布形态;沿锚杆轴向应力分布可划分成波浪段、平台段以及突降段3个阶段。柔性注压锚杆锚固段最大阻抗摩擦应力沿轴向分布近似是均匀的,可实现真正的全长锚固。     

一种风化低品位铁矿石的可选性试验

随着铁矿资源的日益贫乏,对低品位矿石的开发利用成为选矿的发展趋势。山东省某矿业公司矿石属于风化程度较高的低品位铁矿石,样品粒度为10～0mm,含水量1％～2％。根据试样的性质和风化矿分选的经验,采用干式磁选抛尾、干选粗精矿再磨再选的试验流程,获得品位为66％的精矿产品,对低品位铁矿石的开发利用具有一定的借鉴意义。     

尾矿库漫顶溃决动态演化及溃口展宽模型试验

为研究尾矿库漫顶溃决动态演化过程与溃口发展机理及规律,通过3组相似模型试验,对溃口展宽过程和演变机理进行了系统分析,提出了尾矿坝漫顶模式下溃口展宽速率的幂函数公式,并讨论了库水位上升阶段浸润线的变化过程及溃决阶段不同浸润线埋深条件下流速、流量、溃口宽度的变化过程。研究结果表明：尾矿坝的溃决过程可分为坝面漫流与冲沟形成、坝体崩塌与溃口快速扩张及稳定泄流3个阶段;浸润线埋深对流量、流速及溃口最终宽度有较大影响,排渗失效时峰值流量及溃口最终宽度接近正常排渗时的1.5倍,峰值流速可达1.2～1.3倍;降低浸润线高度可以延缓溃决泥石流到达下游的时间,紧急撤离时间也可延长3 min左右;提出的幂函数公式计算值与实测值吻合较好。     

基于GNN的矩阵分解推荐算法

相较于协同过滤,矩阵分解有着更好的拓展性和灵活性,但同样受到数据稀疏和冷启动的困扰。针对上述问题,提出一种融合GNN和PMF的推荐算法GNN_MF。该算法通过神经网络对社交网络图以及用户项目图进行建模,将两个图内在的联系起来,学习目标用户在社会空间以及项目空间上的特征向量。通过MLP将两个特征向量串联提取用户的潜在特征向量,集成在概率矩阵分解模型上,产生预测评分。在真实数据集Epinions、Ciao上的大量实验表明,GNN_MF算法的均方根误差和平均绝对误差较传统PMF分别降低了2.91%、3.10%和4.83%、3.84%。验证了GNN_MF算法在推荐系统中的有效性以及可行性。     

酸碱影响下砂岩流变参数识别方法及敏感度

根据长期暴露在自然环境中的砂质岩体易遭受水及可溶离子化学侵蚀作用的事实,通过对相同浓度不同pH值CaCl₂试剂浸泡处理过的砂岩试件进行三轴剪切试验,根据试验结果选取符合试验规律的二阶简化广义Kelvin流变模型,按照定泊松比假设将其变形为三项应力状态。基于搜索模式的最小二乘方法（LSMPS）获取模型参数最优解,以均方根误差评价模型对各参数变化的敏感性程度。采用延迟时间评价砂岩在不同化学环境中达到稳定蠕变过程所需时间。通过搜索模式识别的模型参数能够使模型计算值与加载试验获得的实测值比较接近,表明该模型及其参数识别方法在确定受化学因素干扰下的砂岩流变特征比较适用。     

Caking property and active components of coal based on group component separation

The content and the caking index of the heavy,the dense medium and the loose medium components of coal,obtained by extraction and stripping with CS_2/N-methyl-2-pyrrolidinone mixed solvent(1:1 by volume),were studied and correlated with the caking property of raw coals.Images of the three group components after heat treatment were analyzed.The results show that both caking index(G) and maximum thickness of plastic layer(Y) of coals have a good linear relationship with the content of the medium component;the dense medium and the loose medium components are the two key factors to determine the caking property of raw coals-they are the source materials of fluidity and swelling of coal,respectively;the heavy component without the swelling and fluidity was cohered by the other components;two new indexes,which can extend current understanding of the caking properties,were introduced.     

Support principles of NPR bolt/cable and control techniques of large-deformation disasters

Deep mining has been paid much more attention because of the depletion of shallow mining resources.Traditional bolts could be invalid to accommodate large displacement and deformation in geomaterials.Consequently, alternative support and reinforcement bolts need to be studied and their constitutive models also need to be developed to help understanding for the complex stress-strain responses of rock masses under loadings. The effect of Negative Poisson's Ratio(NPR) that is attributed to the swelling phenomenon along the lateral direction may appear in metal materials under tensional loadings. Thence NPR materials often have an advantage over NPR ones in mechanical behavior such as impact resistance, antishearing, and energy absorbed. From the characteristics of NPR materials, a series of bolt and cable supports with the effect of NPR and constant-resistance have been recently developed. We here firstly introduce the structural features of NPR support. Then the constitutive model of NPR support is presented and its corresponding equation of energy equilibrium. Its basic principle interacted on rock masses is further discussed. Finally, NPR cables are employed to support the slope of an open-pit mine. The applications show that NPR cables can ease failure within the slope and play an important role in predicting and providing early warning of slope failure, together with a monitoring system of slope stability.     

强迫与混合对流条件下水流顺掠冰柱传热特性

通过实验研究了对流与混合对流条件下水流顺掠冰柱融化过程的相界面移动规律及传热特性。改变冰柱初始尺寸、初始冰柱温度、水流速度与温度等参数,采用工业摄像机记录了冰柱相界面的移动规律,构建了影像实验数据与冰柱相界面传热系数之间的映射关系。通过对实验结果的分析与讨论,获得结论如下：不同速度条件下的平均相界面位置变化趋势相似,相界面随时间呈单调递减幂函数形式变化;平均对流换热系数随水流速度或水流温度的增加而增大,且平均对流换热系数随时间呈递增趋势变化;在不同水流速度或水流温度条件下,Nu 随着Gr／Re 2先增大经过最高点后再减小;获得了水流顺掠冰柱融化过程 Nu 与Gr 、Re 、Pr 及 Ste 之间的经验关联式。     

直墙拱形巷道围岩应力场分析

为得出直墙拱形巷道围岩应力分布规律,应用复变函数弹性理论推导了直墙拱形巷道围岩应力分布的解析表达式。对直墙拱形巷道边界的围岩应力和巷道水平线方向的围岩应力分布规律进行分析,并考虑直墙拱形巷道断面高宽比和侧压系数对其影响规律。研究表明：在不同巷道断面高宽比、侧压系数下,直墙拱形巷道围岩应力集中区域主要集中在直墙底部底角处、拱形顶板中点附近和底板中部3个位置。不同巷道断面高宽比下,直墙拱形巷道沿水平线的应力分布规律基本相同。侧压系数大于1时,采用巷道断面高宽比小于1较有利于巷道稳定;侧压系数小于等于1时,采用巷道断面高宽比大于1较有利于巷道稳定。     

热化学反应法镁合金陶瓷涂层的制备及性能的影响

采用热化学反应法在镁合金基体上制备陶瓷涂层,并对涂层进行耐磨、耐蚀等性能分析.通过XRD物相分析,涂层中有新相生成.且涂层相对基体耐磨、耐蚀性能均有所提高.