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1.
朱建新  赵崇友  郭鑫 《岩土力学》2007,28(8):1605-1608
铲刃以振动的方式作用于土壤,可以有效地降低液压挖掘机挖掘作业时的阻力。从理论上研究了振动掘削岩土的减阻机理,土壤剪切试验结果表明,振动载荷能够使土壤的内摩擦角变小、抗剪强度下降、最大主应力值减小,从而导致挖掘阻力降低;对土壤在静态载荷和振动载荷作用下的失效过程进行了对比仿真实验研究,可知土壤在振动加载的条件下强度显著下降,并提前于相同条件的静态加载而破坏,同时跟踪X方向的载荷发现,振动掘削最大掘削阻力可降低50 %。  相似文献   

2.
许多苏联专家们,尤其是近年来,从事着发展和推行用振动法打椿,打筒子和管子以及钻孔的巨大工作。振动法的创始人是Д.Д.巴尔金,他首创了工业振动器的构造和振动打入理论。Д.Д.巴尔金的首批著作对发展振动方法和在建筑、钻探工作中推行这种方法有具大的影响;同时,在这些著作的影响下出现了许多著作和研究者。  相似文献   

3.
本文全面阐述了珠江三角洲这个广东省大、中型工业企业的集结区,城市生活垃圾和工业“三废”污染方面严重的环境地质问题;同时介绍了本区存在的特殊灾害类型——自喷二氧化碳气对环境的污染和造成的危害。由于本区的工业企业多以煤为燃料,也产生了大量的二氧化碳等有害气体,致使中南地区变成了酸雨区。珠江三角洲近年来酸雨频繁,范围广、强度大,已形成以广州为中心的酸雨分布区。由于“三废”排放引起的环境污染和酸雨的频繁袭击,直接破坏土壤、危害农田、影响农作物的生长。文中讨论了环境恶化与灾害频发的关系,并以广州市为例,介绍了“七五”期间对环境保护工作的综合治理概况。  相似文献   

4.
绍了采用控制爆破拆除大跨度工业厂房的施工方法,主要论述了在要求振动较小情况下,怎样控制爆破参数。  相似文献   

5.
为探究精密仪器厂房防微振结构设计方法,本文分别通过现场实测和数值模拟方法对苏州某高科技电子工业厂区一单层轻钢结构厂房微振动水平进行了评价和分析。对该厂区进行场地环境振动实测,对比了厂房建成前后地坪振动特性;利用ANSYS软件建立了厂房有限元模型,分析了Rayleigh阻尼和底板厚度对厂房振动特性的影响。研究结果表明:厂房建成后底板振动满足振动限值要求;厂房的桩筏基础有明显的减振效果,但对不同方向和频段地面的振动影响有所差异;阻尼比和底板厚度对结构主频影响较小,而对振幅影响较大,阻尼比在1~3 Hz和10~50 Hz的频段内对振幅影响较大,底板厚度在50 Hz以下对振幅影响较大。因此,在厂房防微振设计时,适当增加底板厚度和阻尼可减小中低频振动,从而达到较好的减振效果。  相似文献   

6.
江苏省溧水县土壤环境污染预警预测方法探讨   总被引:5,自引:0,他引:5  
介绍了溧县土壤环境质量的现状。溧水县主要有黄砂土、栗色土、岗黄土、黄岗土、马肝土、板浆白土、青泥条、青泥土等8种土壤类型。通过地球化学调查和对溧水县土壤的系统采样,获得了反映土壤质量的地球化学数据。通过对土壤中污染物富集历史的研究,揭示了土壤污染物的演化趋势。通过寻找零污染的历史时间结合现代土壤地球化学调查数据,建立了土壤重金属污染预警预测的数学模型。提出了影响土壤质量的关键因子和土壤污染的影响因素,得出了工业是影响土壤质量的主要因子,土壤污染在不断加速的结论。  相似文献   

7.
振动锤沉拔钢护筒与旋挖钻机钻进工艺相结合,充分发挥了振动锤适用于软土地区各种施工环境和各类桩型,包括陆地、水上、水下的打桩、拔桩、沉箱作业,地下防渗墙、土壤压实优越性,也发挥了旋挖钻机施工速度快的优越性,同时也拓宽了旋挖钻机对软土地区施工的领域,提高了旋挖钻机施工软土地区桩基的效率和质量,为旋挖钻机施工类似地层提供了技术参考和借鉴的经验。  相似文献   

8.
为了研究有机氯农药(OCPs)在表层岩溶带土壤中的分布趋势、组成特征和来源,采用气相色谱-微池电子捕获检测器(GC-μECD)分析了重庆市南川区水房泉、后沟泉、柏树湾泉、兰花沟泉等典型表层带岩溶泉上覆土层中有机氯农药的浓度。结果显示,总体上表层岩溶带土壤中的OCPs的浓度范围是7.13~323.37ng/g,其中后沟泉、柏树湾泉、兰花沟泉表层土壤中的17种OCPs检出率为100%,水房泉土壤中除p,p'-DDD外其余全部检出,但不同种类有机氯含量差异较大。其中HCHs、DDTs、CHLs、灭蚁灵是主要检出物。研究区内土壤样品中的HCHs来源于工业品HCHs和林丹使用的残留,且由于环境影响,土壤中HCH的同系物组成发生了明显变化。水房泉和柏树湾泉土壤中的DDTs来自于工业DDTs和三氯杀螨醇的混合源,而后沟泉和兰花沟泉土壤中的DDTs可能来自于工业DDTs的使用,而非三氯杀螨醇类型的DDT。对比中国和荷兰的土壤质量标准,柏树湾泉土壤中DDTs浓度接近于荷兰无污染土壤的参考值,兰花沟泉土壤中的DDTs应属于轻度污染,后沟泉土壤中的DDTs和氯丹类化合物污染程度较重,而水房泉土壤为无污染土壤。   相似文献   

9.
为探明上海低效工业用地土壤重金属含量特征及生态风险状况,在某区域选取3种典型低效工业用地地块,分别检测As、Cd、Cr、Cu、Pb、Ni、Zn、Hg八种重金属。结果表明:区域内土壤重金属因人类活动呈现出富集现象,其中个别点位Cd、Hg、Ni超标,大部分点位重金属均超过背景值。Pearson相关性分析研究发现:Hg与Cd可能主要来源于生活垃圾及周边电镀等工业企业;Cu、Pb、Ni、Zn和Cr可能主要来自于生活污水、工业废气、汽车尾气,污染气体中的重金属通过干湿降落后渗入土壤;As可能主要受成土母质的影响。潜在生态风险评价及生态风险预警结果表明:以上海市背景值为参照,Hg和Cd处于中等至高等风险水平,其它重金属皆为低风险水平。  相似文献   

10.
长三角经济高速发展地区土壤pH时空变化及其影响因素   总被引:13,自引:0,他引:13  
通过调查和分析长三角地区张家港市2004年和第二次土壤普查时(1980)的土壤pH,探讨了该市近20年来基于经济高速发展影响下的土壤pH变化及影响因素。结果表明,自第二次土壤普查以来,该市土壤pH变化明显。南部人为土地区绝大部分土壤pH值都下降了一个单位,平均值由7.39降至6.33;北部雏形土区,两个时期的土壤pH值分别为7.92和7.98。土壤pH的降低可能同该地区长期施用化学肥料、酸雨及工业酸性“三废”排放的增加有关。此外,土地利用和田间管理也对土壤pH变化起着较为重要的作用,而土壤地球化学性质差异则是导致南北地区土壤pH变化不同的内在因素。  相似文献   

11.
The diffusion coefficients of aquo metal ions (Mz+) and their EDTA complexes (M-EDTA(z−4)+) were compared to understand the effect of EDTA complexation on the diffusion of metal ions by the diffusion cell method for Co2+, Ga3+, Rb+, Sr2+, Ag+, Cd2+, Cs+, Th4+, , and trivalent lanthanides. Most studies about ionic diffusion in water have dealt with free ion (hydrated ion). In many cases, however, polyvalent ions are dissolved as complexed species in natural waters. Hence, we need to study the diffusion behavior of complexes in order to understand the diffusion phenomenon in natural aquifer and to measure speciation by diffusive gradient in thin films (DGT), which requires the diffusion coefficients of the species examined. For many ions, the diffusion coefficients of M-EDTA(z−4)+ are smaller than those of hydrated ions, but the diffusion coefficients of M-EDTA(z−4)+ are larger than those of hydrated ions for ions with high ionic potentials (Ga3+ and Th4+). As a result, the diffusion coefficients of EDTA complexes are similar among various metal ions. In other words, the diffusion of each ion loses its characteristics by the complexation with EDTA. Although the difference is subtle, it was also found that the diffusion coefficients of EDTA complexes increase as the ionic potential increases, which can be explained by the size of the EDTA complex of each metal ion.  相似文献   

12.
Flyrock arising from blasting operations is one of the crucial and complex problems in mining industry and its prediction plays an important role in the minimization of related hazards. In past years, various empirical methods were developed for the prediction of flyrock distance using statistical analysis techniques, which have very low predictive capacity. Artificial intelligence (AI) techniques are now being used as alternate statistical techniques. In this paper, two predictive models were developed by using AI techniques to predict flyrock distance in Sungun copper mine of Iran. One of the models employed artificial neural network (ANN), and another, fuzzy logic. The results showed that both models were useful and efficient whereas the fuzzy model exhibited high performance than ANN model for predicting flyrock distance. The performance of the models showed that the AI is a good tool for minimizing the uncertainties in the blasting operations.  相似文献   

13.
Naturally occurring organic ligands, such as acetate, citrate, malonate, oxalate, and succinate, play important roles in mobility and accumulation of La and other rare earth elements in low temperature systems under Earth surface conditions. However, a comprehensive and consistent thermodynamic database covering the complexes of rare earth elements with those naturally occurring organic ligands is lacking. In this study, thermodynamic data of organic species of rare earth elements (REE) represented by La, with an emphasis on their aqueous complexes with organic ligands, are critically reviewed. The organic ligands covered by this study include acetate, citrate, malonate, oxalate and succinate. In this critical review, the Specific Interaction Theory (SIT) model is adopted for extrapolation to infinite dilution. This model is a reliable activity coefficient model valid for a wide range of ionic strengths. These critically reviewed data, including complex formation constants, SIT interaction coefficients and solubility product constants, would enable accurate modeling of the speciation and solubility of REE in various environments including high ionic strength environments, providing insight into mobility and enrichment of REE in various environments.  相似文献   

14.
本文介绍了计算对称四极电测深滤波系数的最小二乘法,并给出了两组偏心率(MN/AB)分别为1/8和1/5的正演滤波系数.取样间隔都为0.6,前者共15个系数,后者共13个系数.本文还说明了滤波器的精度和考虑测量极距大小的必要性.  相似文献   

15.
Coefficients of association have been widely employed in cluster analysis. However, their use has been, for the most part, restricted to binary data. This limitation can be overcome by redefining positive and negative matches and mismatches in terms of minimum and maximum values of paired elements of parallel vector arrays. Rewriting the algorithms of coefficients of association with these new components gives the new “quantified” coefficients general utility for binary, ordered multistate, and quantitative data, while retaining their original analytic properties. Quantified coefficients of association avoid several problems of shape and size that are associated with correlation coefficients and measures of Euclidean distance. However, when measuring similarity, quantified coefficients weight each attribute of an object by that attribute's magnitude. A related set of similarity indices termed “mean ratios” is introduced; these indices give each attribute equal weight in all situations. Both quantified coefficients of association and mean ratios are related to a number of measures of similarity introduced to various fields of scientific research during the past 50 years. A review of this literature is included in an attempt to consolidate methodology and simplify nomenclature.  相似文献   

16.
为克服马氏距离判别模型无法考虑指标权重的不足,引入粗糙集理论,通过分析评判方法对评价对象的支持度和重要性计算得到权重系数。将权重系数嵌入距离判别模型,构建了边坡稳定性预测的加权距离判别模型。根据边坡失稳破坏特点,选取合理的判别因子,以大量工程实例样本作为原始数据和训练样本,建立了边坡稳定性评价预测的粗糙集-距离判别模型。将边坡稳定性评价预测的粗糙集-距离判别模型评价预测结果与马氏距离判别法、支持向量机理论、Bayes判别分析等方法得到的预测结果进行了对比分析,验证了粗糙集-距离判别模型的有效性。将建立的粗糙集-距离判别模型应用于黄河中游地区某大型水利枢纽库区边坡工程,预测结果与实际情况吻合。研究结果表明,粗糙集-距离判别模型具有权重分析合理、预测准确性高等优点,是进行边坡稳定性分析预测的一种新的有效途径。  相似文献   

17.
李斌  王大国  何治良  王鹏 《岩土力学》2022,43(10):2689-2697
岩石三轴强度包络线通常为非线性,通过线性回归法(LRM)获得的抗剪强度参数对围压的变化具有很高的敏感性。为使 LRM能够考虑围压对抗剪强度参数估计的影响,定义了岩石三轴强度围压效应系数,构造一个指数函数表示该系数与围压的关系,并将其引入到 LRM 的修正中,提出考虑围压效应的线性回归分析法(CCPE-LRM)。同时,提出了CCPE-LRM 的合理性检验方法,并定义了距离系数作为指标来表征抗剪强度参数估计值与参数实际值的差异。通过以公开发表文献中多种类型岩石的三轴强度数据为例进行验证分析,结果显示各种岩石的距离系数均较小,CCPE-LRM 获得的抗剪强度包络线紧贴摩尔圆,且近似相切状态。表明通过CCPE-LRM 获得的抗剪强度包络线在一定程度上可以代替理想抗剪强度包络线,该方法估计的抗剪强度参数与理论抗剪强度参数的一致性较高,证明CCPE-LRM 具有较好的适用性。  相似文献   

18.
The relationship between the brightness in the FeXIV 530.3 nm coronal green line and magnetic fields on various scales in the corona is studied quantitatively. The cross-correlations of the corresponding synoptic maps for 1977–2001 have been calculated. Maps of the brightness of the coronal green line are constructed using daily monitoring data. Maps of the magnetic field are constructed separately for fields on large and small spatial scales, based on computations in a potential approximation using photospheric observations for distances of 1.1R carried out at the Wilcox Solar Observatory. The correlations between the brightness in the coronal green line and the magnetic-field strengths on various scales as a function of latitude have a cyclic character. The correlation coefficients in the spot-formation zone are positive. Here, the green-line brightness corresponds mainly to the strength of small-scale fields, corresponding to the sizes of large active regions and activity complexes. The correlation coefficients are sign-variable above 40° latitude, and reach their greatest positive and negative values at the cyclemaximum and minimum. Larger-scale fields influence the green-line brightness at higher latitudes and near the phase of the cycle minimum. The results obtained can be used to investigate mechanisms for heating the corona. The relationship between the results obtained and the subsurface and deep solar dynamos are also discussed.  相似文献   

19.
Carbonatites are believed to have crystallized either from mantle-derived primary carbonate magmas or from secondary melts derived from carbonated silicate magmas through liquid immiscibility or from residual melts of fractional crystallization of silicate magmas. Although the observed coexistence of carbonatites and alkaline silicate rocks in most complexes, their coeval emplacement in many, and overlapping initial87Sr/86Sr and143Nd/144Nd ratios are supportive of their cogenesis; there have been few efforts to devise a quantitative method to identify the magmatic processes. In the present study we have made an attempt to accomplish this by modeling the trace element contents of carbonatites and coeval alkaline silicate rocks of Amba Dongar complex, India. Trace element data suggest that the carbonatites and alkaline silicate rocks of this complex are products of fractional crystallization of two separate parental melts. Using the available silicate melt-carbonate melt partition coefficients for various trace elements, and the observed data from carbonatites, we have tried to simulate trace element distribution pattern for the parental silicate melt. The results of the modeling not only support the hypothesis of silicate-carbonate melt immiscibility for the evolution of Amba Dongar but also establish a procedure to test the above hypothesis in such complexes.  相似文献   

20.
梁友嘉  徐中民 《冰川冻土》2013,35(1):249-354
尽管近年来统计数据的生成技术有了很大提高, 但可用的详细GDP空间分布数据始终难以得到满足. 以夜间灯光辐射数据、 官方统计数据和已有空间化人口分布数据构建了一种GDP空间化建模方法, 得到张掖市甘州区2000年的GDP空间分布. 首先, 分析基于乡镇单元的GDP与对应的夜间灯光辐射数据DN值之间的关系, 得到GDP模拟模型; 然后结合人口空间分布数据和三次产业的比例, 得到基于500 m×500 m栅格的GDP空间分布图. 各乡镇的GDP平均值为372×104元, 标准差为34×104元.  相似文献   

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