Influence of depth-thickness ratio of mining on the stability of a bedding slope with its sliding surface in concave deformation

In order to study the influence of depth-thickness ratio on bedding slope stability, whose sliding surface is flexural concave in shape under mining conditions, this paper aims to study the characteristics of deformation and damage of bedding sliding with depth-thickness ratios of 200:1, 150:1, 120:1, 100:1 and 50:1by adopting numerical simulation analysis software combined with laboratory-made ‘‘under the influence of mining variable sliding surface slope similar simulation test bed", and to propose identification methods for slope stability under the influence of mining. The results show that mining activities under the slope reduce slope stability. With a decrease in the mining depth ratio, the influence of mining on the slope increases gradually, and the damage to the slope gradually expands, the stability of the slope gradually reduces, fracture occurs on the slope toe and the central fissure gradually develops to the surface,and reaches slide threshold when the depth-thickness ratio is 50:1.

Study on determination of the stable slope configuration for deep open pit mine

The space effects of deep pit slope are analyzed by an elastic mechanics principle. The interaction among the critical slide angle, the friction coefficient, the cohesion, and the horizontal radius of the deep pits is derived in this paper. It indicates that the deeper the pit is excavated, the greater the critical slide angle is. Both the theory for reducing stripping waste rock in deep pit and the approach to determining the configuration of the stable slope are developed from the interaction. The theory in this paper comprises the preceding principles of stability analysis of slopes and is suitable for analyzing that of deep pit.

Determination of the Stable Slope Configuration of Oval-Shaped Furrow Pits

The space effects of oval-shaped furrow pit slopes were analyzed by the elastic mechanics principle.The interaction of limit equilibrium slope angle,friction coefficient,cohesion and horizontal radius of oval-shaped furrow pits has been derived.The oval trumpet-like rock mass is homogeneous and elastic while only loaded by its dead weight.The interaction indicates that the deeper an oval-shaped furrow pit is excavated,the greater the limit equilibrium slope angle.Both the theory base for reducing stripping waste rock in an oval-shaped furrow pit and the basic way to determine the configuration of a stable slope were developed from the mentioned interaction.The theory includes the preceding principles of stability analysis of slopes.Compared with the configuration determined by traditional theory of slope stability,a great quantity of stripping waste rock can be reduced by that determined in this paper under stable conditions.

基于非对称幅度插值的二维来波方位估计

幅度插值方位估计法通过对少数几个波束采样插值得到来波方位,避免了密集的方位搜索,在工程中有广泛的应用。目前该方法大多基于一维,且使用对称函数进行插值,估计误差较高。本文通过解耦的方式将该方法由一维推广至二维任意阵,并考虑真实方位谱在偏离0°后左右波束不对称的情况,利用左右波束斜率比作为求解条件,使用非对称函数进行幅度插值。进一步,针对二维非对称插值中出现的角度失配问题,提出了迭代插值的解决方法。最后仿真分析了插值方法、迭代插值以及信噪比对插值精度的影响,所提出方法的插值精度优于传统对称插值方法;且通过千岛湖实验数据验证,所提方法以10°间隔插值得到的估计精度可以比拟常规波束形成以0.01°进行密集扫描的估计精度。所提方法能够在满足一些工程应用中对实时性要求的同时达到较高的方位估计精度。

陕西省安康市瀛湖镇滑坡灾害分布特征与易发性分析

开展滑坡易发性评价是防灾减灾工作的基础科学前提。陕西省安康市汉滨区是滑坡灾害多发区,为研究滑坡提供了良好的窗口。本文以汉滨区瀛湖镇为典例,综合选取高程、地形起伏度、斜坡结构、坡向、高程变异系数、覆盖层厚度、坡度、归一化植被系数(NDVI)、距道路距离和距河流距离等10项影响因子,以斜坡单元为评价依据,采用频率比(FR)分析了滑坡分布特征。进一步基于逻辑回归-频率比组合法(LR-FR)开展研究区的滑坡易发性评价,并对结果进行检验与分析。结果显示高程变异系数、地形起伏度、坡向和距道路距离为研究区影响滑坡发育的主控因子;LR-FR的成功率和预测率分别为0.804、0.843;极高易发区与高易发区主要分布在瀛湖水库两岸以及道路和河流附近,两区占斜坡总面积的33.66%,其中滑坡发育面积为1.08 km^(2),占滑坡总面积的84.36%,与实际滑坡的分布具有良好的一致性,表明易发性评价结果可靠。研究成果为汉滨区瀛湖镇地质灾害风险管控以及类似地区滑坡易发性评价研究工作提供了新的基础参考依据。

玉米间作大豆行比配置对坡耕地水土流失的影响

[目的]探究玉米间作大豆不同行比配置的水土流失规律,为坡耕地具有水土保持效果的玉米间作大豆模式推广利用提供科学依据。[方法]在坡耕地条件下以玉米间作大豆为研究对象,选定坡度(10°,16°,22°)和降雨强度(40,80,120 mm/h),通过人工模拟降雨试验,探究玉米、大豆单作及玉米‖大豆2∶1(2行玉米间作1行大豆),2∶2,2∶3,2∶4行比配置的水土流失特征。[结果]玉米‖大豆2∶4行比配置较玉米单作、玉米‖大豆2∶1,2∶2,2∶3行比配置、大豆单作地表径流量平均减少64.23%,57.19%,31.17%,10.12%,0.36%,侵蚀量平均减少82.90%,80.75%,46.53%,29.78%,36.33%,地表径流产流时间平均延缓101.55%,49.06%,23.13%,30.77%,0.82%。雨强和径流产生时间、入渗流产生时间呈极显著负相关,和径流量、侵蚀量呈极显著正相关,坡度和径流产生时间呈显著负相关,在高雨强、高坡度下间作较大豆单作水土保持效果表现更好。[结论]总体来看,玉米‖大豆2∶4行比配置在不同雨强和坡度下水土保持效果较好,是一种合理可行的山区坡耕地作物多样性种植方式。

斜率与变统计周期微细电火花脉冲识别系统

针对电压阈值法不能很好统计开路时长和改变放电电压时需要调节电压阈值等问题。提出一种基于斜率比值和变统计周期的脉冲识别方法,该方法使检测装置直接用于微细电火花粗磨、精磨两种不同开路电压的加工情形中,不需要调节电压阈值且能有效的统计开路时长,从而提高检测效率和精度。首先使用NI采集卡和LabVIEW软件开发脉冲识别系统,该系统可对间隙电压进行显示、连续存储以及对文件进行拆分,接着对斜率比值法和变统计周期法进行理论分析并编写脉冲识别与统计程序,最后进行放电状态检测的实验验证。结果表明:该方法能够识别不同脉冲且适用于不同放电电压情形,程序结果与实际结果较吻合,证明了该方法的有效性和实用性。

干旱半干旱区岩质边坡生态基材防护特性与优化配比

为修复干旱半干旱区岩质边坡的生态系统,获得生态护坡基材的优化配比,以一种新型生态基材为研究对象,以黏结剂、木纤维、保水剂为3个因素,各取3个水平,开展多指标多因素正交试验探索各因素和水平对基材性能的影响规律。结果表明:黏结剂可以有效提升基材的强度和水稳性能,与适量水分作用可以发挥最优效能。随其掺量的增加,抗剪强度表现为先增加后减小,渗透系数和崩解量均表现为减小;施用较少剂量的保水剂即可对基材的渗透、持水性能产生较大的影响,有效提高基材固持自然降水的能力;木纤维与黏结剂的相互作用,可以促进其对基材的加筋补强和改善土壤构型效能的发挥,增强基材的抗冲抗剪性能。除渗透系数随木纤维掺量的增加而增加外,其他指标均呈先增大后减小的趋势。由极差分析可得,各因素对基材性能的影响程度表现为黏结剂>木纤维>保水剂,获得基材的最优配比为黏结剂3%,木纤维4%,保水剂0.1%,最优含水率为16%。

人工修复边坡植被演替初期有机碳组分及土壤生态化学计量特征

[目的]研究人工修复边坡演替初期土壤有机碳组分、碳氮磷含量及其化学计量比,揭示气候因子对人工修复边坡演替初期土壤有机碳组分、碳氮磷含量及其化学计量比的影响,以期为后期人工修复边坡的养护提供指导和建议,确保人工修复边坡的正向演替。[方法]在湛江、梧州、宜昌、南阳、焦作、潍坊、加查采集了初期基材配制相同、植物配制相近,修复年限为2~4年的植被混凝土人工修复边坡土样,通过实验获得土样有机碳组分、碳、氮、磷的数据,采用冗余分析,开展气候因子对人工修复边坡演替初期土壤有机碳组分、碳氮磷含量及其化学计量比的影响研究。[结果]人工修复边坡演替初期F_(1)含量的变化范围为1.10~3.64 g/kg;F_(2)含量的变化范围为1.33~3.04 g/kg;F_(3)含量的变化范围为2.02~3.34 g/kg;F_(4)含量的变化范围为10.86~15.24 g/kg;TOC含量变化范围为15.52~24.71 g/kg;TN含量变化范围为0.61~0.93 g/kg;TP含量的变化范围为0.81~1.22 g/kg;C∶N变化范围为23.55~27.95;C∶P变化范围为17.26~23.09;N∶P的变化范围为0.72~0.98;C∶N∶P的变化范围为17.26∶0.75∶1~24.81∶0.95∶1。[结论]演替初期人工修复边坡碳磷表现为中等及以上,氮表现为缺乏;有机碳组分以惰性有机碳为主且有机碳稳定性较强。有机碳组分的主要影响因子为年平均温度、物种丰富度和年平均降水;土壤碳氮磷含量及其化学计量比主要影响因子为年平均温度、物种丰富度、pH和容重。

坡度条件下不同长宽比矩形火源燃烧火焰贴地长度实验研究

利用可变角度实验台,改变斜坡角度(10°~50°)、热释放速率(12.3~24.6 kW)以及燃烧器长宽比(1~6),开展了一系列燃烧实验,研究了火焰贴地长度随这3个因素的演变规律.结果表明,随着斜坡角度、火源热释放速率及燃烧器长宽比的增加,火焰贴地长度增加.对于相同的坡度和火源热释放速率,随长宽比增大,贴地长度增幅范围在65%~105%之间.基于斜坡诱导压差与火羽流浮力共同作用的物理机制分析,并考虑到燃烧器长宽比对火焰卷吸行为的影响,提出了无量纲火焰贴地长度预测模型.

基于GEO-SLOPE的互层土边坡稳定性研究

GEO-SLOPE是边坡工程中广泛应用的一种稳定性分析软件,提供了基于极限平衡法的多种边坡稳定计算方法,本文在前人研究的基础上,分析互层土形成的独特性,其土层类别、层厚比等特征是影响互层土边坡稳定性的重要因素,选用互层土的水平层理构造,利用GEO-SLOPE软件中的SLOPE/W模块功能,对互层土边坡中的淤泥质与粉砂互层、粉砂与淤泥质土互层按不同层厚比进行稳定性计算和分析,分别计算各工况下其安全系数,结果为今后互层土边坡研究提供可借鉴的方法。

弹簧-坡面变摩擦阻尼器参数研究

本文是针对变摩擦阻尼器无系统研究方法及具体规范的支撑。通过理论推导得出单自由度体系在谐振激励下结构位移、耗能比计算公式并确定摩擦系数、坡面长度、坡度和碟簧刚度等为影响弹簧-坡面变摩擦阻尼器力学性能的重要参数,采用自编程序对弹簧-坡面变摩擦阻尼器进行参数分析,研究结果发现:(1)弹簧-坡面变摩擦阻尼器摩擦系数宜取0.5以上;(2)宜适当增加坡面长度且平面段长度宜小于结构屈服位移;(3)当弹簧-坡面变摩擦阻尼器耗能不足时,宜优先考虑增大坡度;(4)当增大坡度仍无法满足弹簧-坡面变摩擦阻尼器耗能需求时,可考虑增大碟簧刚度。研究结果为实际工程应用中弹簧-坡面变摩擦阻尼器参数确定提供参考。

Concentration and Characterization of Colored Dissolved Organic Matter in the Surface Microlayer and Subsurface Water of the Yellow Sea and the East China Sea

The distribution and chemical properties of colored dissolved organic matter(CDOM) in the Yellow Sea and the East China Sea during December 2011-January 2012 were investigated. The input of freshwater and biological activities had an evident influence on the CDOM levels(characterized by the light absorption coefficient at the wavelength of 355 nm a_(355)) in the study area. The spatial distribution of CDOM levels displayed a gradually decreasing trend from the coastal waters(0.37 m^(-1)) to the open sea(0.18 m^(-1)). The spectral slope ratio(the slope ratio S_R defined as S_(275-295):S_(350-400)) during the cruise was correlated with salinity, and exhibited a large variation from inshore(average of 2.515) to offshore sites(average of 5.327) compared with the distribution of a_(355). The values of S_R were related to CDOM molecular weight(MW). The a_(355), S_R, and chlorophyll a in 37 samples collected from the surface microlayer were significantly correlated with those in the corresponding subsurface water samples, implying a strong exchange action between the microlayer and bulk water. The a_(355) and S_R of CDOM exhibited significant microlayer enrichment, with mean enrichment factors(EFs) of 1.72 and 1.62, respectively.

High Slope Stability of Diversion Power System Intake of Jinchuan Hydropower Station

The excavated height of the left bank slope of the diversion power system intake in Jinchuan hydropower station is about 160 m. The stability and safety of the slope during construction and its operation/utilization become one of the most important geological engineering problems. At the same time, it is also crucial to select a safe and economic excavation gradient for the construction.We studied the problem of how to select a safe and economic slope ratio by analyzing the geological condition of the high slope, including the lithology,slope structure, structural surface and their combinations, rock weathering and unloading,hydrology, and the natural gradient. The study results showed that the use of an excavation gradient larger than the gradient observed during site investigation and the gradient recommended in standards and field practice manuals is feasible. Then, we used the finite element method and rigid limit equilibrium method to evaluate the stability of the excavation slope under natural, rainstorm and earthquake conditions. The calculated results showed that the excavated slope only has limited failure, but its stability is greatly satisfactory. The research findings can be useful in excavation and slope stabilization projects.

基于斜率比法评定断奶仔猪对不同铜源的相对生物学利用率

本试验旨在研究不同铜源(硫酸铜、碱式氯化铜和柠檬酸铜)和铜添加水平(20和30 mg/kg)对断奶仔猪生长性能、血清铜含量与含铜酶活性以及组织铜含量的影响,探讨断奶仔猪对不同铜源的相对生物学利用率。试验采用3×2双因子随机区组设计,选取平均体重为(8.98±0.48)kg的杜×长×大三元杂交断奶仔猪112头,随机分为7组,每组4个重复,每个重复4头猪。对照组饲喂玉米-豆粕型基础饲粮(铜含量为7.80 mg/kg),各试验组分别在基础饲粮中添加20或30 mg/kg硫酸铜、碱式氯化铜或柠檬酸铜(均以铜含量计)。试验预试期3 d,正试期28 d。结果表明:1)试验组与对照组断奶仔猪平均日增重、平均日采食量和料重比均无显著差异(P>0.05)。2)饲粮铜源和铜添加水平对断奶仔猪血清铜含量具有显著影响(P<0.05),但对血清铜蓝蛋白和铜锌超氧化物歧化酶活性均无显著影响(P>0.05)。3)饲粮铜源和铜添加水平对断奶仔猪肝脏铜含量具有显著影响(P<0.05),但对心脏、肾脏、胰脏和跖骨铜含量均无显著影响(P>0.05)。4)根据多元线性回归斜率比法计算,以血清铜含量为评价指标,碱式氯化铜和柠檬酸铜相对于硫酸铜(100%)的生物学利用率分别为110.39%和120.78%;以肝脏铜含量为评价指标,碱式氯化铜和柠檬酸铜相对于硫酸铜(100%)的生物学利用率分别为119.39%和136.09%。综上所述,本试验条件下,断奶仔猪对低铜饲粮(铜添加水平为20或30 mg/kg)中3种铜源的相对生物学利用率表现为柠檬酸铜>碱式氯化铜>硫酸铜。

A Testing Method for Ratio Restraint Characteristics of Differential Relay Protection of Transformers

In this paper, a method to calculate the slope of the ratio restraint characteristic of a transformer differential relay protection is proposed. The method allows using some concise but effective means to get the slope. Modulating the argument of current output from ONLLY testing equipment can make the relay protection device operate, thus, the data used for calculation would be obtained naturally after several trails. In order to make sure how effective that method could be, some experiment data is given as well.

Upper Bound Solution of Soil Slope Stability under Coupling Effect of Rainfall and Earthquake

Based on the limit analysis upper bound method,a new model of soil slope collapse has been proposed which consists of two rigid block zones and a plastic shear zone.Soil slope was induced failure by coupling effect of rainfall and earthquake,and these blocks were also incorporated horizontal earthquake force and vertical gravitate.The velocities and forces were analyzed in three blocks,and the expression of velocity discontinuities was obtained by the principle of incompressibility.The external force work for the blocks,the internal energy of the plastic shear zone and the velocity discontinuous were solved.The present stability ratios are compared to the prevenient research,which shows the superiority of the mechanism and rationality of the analysis.The critical height of the soil slope can provide theoretical basis for slope support and design.

草灌比例对新垦山地田埂边坡生态护坡效果的影响研究

山地开垦过程中形成的裸露边坡在水力侵蚀和重力侵蚀下易坍塌,直接影响到田地的耕作,因此在开发新垦山地的同时,需采取配套的生态护坡措施,将人为造地对生态的影响降到最低。选择本地草种狗牙根与马棘、胡枝子、盐肤木3种灌木,分别设置17.4%、13.6%、9.5%、5%四种草本比例在新垦山地的田埂边坡进行草灌混播试验,结果表明:草本比例过高会使植物密度过大,影响灌木的生长,不利于边坡稳固;综合混播植物生长情况、恢复的植物数量、土壤含水率、土壤抗剪强度和土壤紧实度情况来看,以草本比例5%为最优比例,此比例既可在喷播初期让草本快速发挥护坡作用,又不影响灌木生长,且可节省施工时的材料成本,可为新垦山地的生态护坡技术提供借鉴。

边坡稳定确定性设计与可靠度设计的安全判据等价性充分条件

边坡稳定设计中不可避免地存在多种不确定性,确定性设计方法难以合理地考虑各种不确定性。相对而言,可靠度设计方法能够定量考虑岩土工程设计中的不确定性因素。确定性设计与可靠度设计采用了不同的安全判据,具有相同安全系数的设计方案的可靠度水平可能不同,导致两种设计方法的设计可行域不一致(即两种设计方法安全判据不等价),阻碍了可靠度设计方法在工程实践中的应用。相对安全率和广义可靠指标相对安全率建立了两种设计方法安全判据之间的定量联系,将广义可靠指标相对安全率应用于边坡稳定可靠度设计,提出边坡稳定确定设计与可靠度设计的安全判据等价性充分条件。基于随机场模型研究了单层和双层土质边坡确定性设计与可靠度设计的等价关系。结果表明:考虑空间变异性条件下,单层边坡可以满足所提充分条件,确定性设计与可靠度设计可以得到相同的设计可行域;相反,双层边坡不满足所提充分条件,难以建立两种设计安全判据的等价关系。

ESTIMATION OF BLENDING RATIO OF TWO-COMPONENT FIBER BUNDLE FROM BUNDLE LOAD-ELONGATION CURVE

In this paper, two methods were developed to assess the blending ratio of two-componentfiber bundles. They were the peak-height method and the slope method. The relationship be-tween blending ratio and testing data was analysed, and the regression curves were obtained bystepwise regression method. It was pointed out that the testing errors of both methods were lessthan two percent. The validities of both methods were verified by experiments, All calculationsof both methods were completed by computer. The blending ratio was ascertained from the test-ing data of bundle fiber strength tester which was made by the authors themselves.