论高岭石粘土和铝土矿研究的新进展

过去我国地质界向前苏联学习,把球粘土(Ballclay)作为高岭土或耐火粘土的一个变种,使我们找矿走入误区,以致后来从美国进口球粘土。其实球粘土的结晶性质这个内在因素与高岭土或耐火粘土常不相同,则派生的性能更不一样,应成为独立的矿种,还可与国际接轨。又过去国内外学者认为高岭石高度有序为热液型的,而沉积型的为无序高岭石。但笔者等的研究,我国高岭石高度有序而规模大且均匀稳定的,应算沉积型的紫矸(古生代高岭石软质粘土),可以作流动性好的造纸涂料。又我国硬水铝石岩溶铝土矿,应属于生物有机质成矿作用的沉积型铝土矿。     

Free-Swell and Swelling Pressure of Unsaturated Compacted Clays; Experiments and Neural Networks Modeling

Expansive soils have received attentions of several investigators in the past half of century in the problematic soils context. Volume change behavior of unsaturated compacted soils in presence of water and change of degree of saturation was observed in two form of heave or collapse. Low water content and low density compacted soils in presence of enough surcharge pressure lose stability and collapse, because of their metastable and susceptible structure to change of degree of saturation. Free-swell and swelling pressure of five compacted clays, covering low to high plastic clays have been investigated in respect to compaction states and swelling pressure was compared with collapse pressure threshold. The results of experiments were utilized in two Artificial Neural Networks to predict free-swell percent and swelling pressure of a soil sample based on index properties and compaction state.     

采用新型灌浆材料的石墙抗震性能研究

基于石砌墙体的特点、对比研究和拟动力试验,提出新型材料在石墙抗震加固中的应用,经系列试验研究,提出相应的抗震抗剪强度理论,反映了工程情况,符合震害规律。     

Liquefaction mitigation in silty soils using composite stone columns and dynamic compaction

The objective of this study is to develop an analytical methodology to evaluate the effectiveness ofvibro stone column (S. C.) and dynamic compaction (D.C.) techniques supplemented with wick drains to densify and mitigate liquethctionin saturated sands and non-plastic silty soils. It includes the following: (i) develop numerical models to simulate and analyze soil densification during S.C. installation and D.C. process, and (ii) identify parameters controlling post-improvement soil density in both cases, and (iii) develop design guidelines for densification of silty soils using the above techniques. An analytical procedure was developed and used to simulate soil response during S.C. and D.C. installations, and the results were compared with available case history data. Important construction design parameters and soil properties that affect the effectiveness of these techniques, and construction design choices suitable for sands and non-plastic silty soils were identified. The methodology is expected to advance the use of S.C. and DC. in silty soils reducing the reliance on expensive field trials as a design tool. The ultimate outcome of this research will be design charts and design guidelines for using composite stone columns and composite dynamic compaction techniques in liquefaction mitigation of saturated silty soils.     

孔隙变化对吹填土地基真空预压固结的影响

吹填地基真空加固过程中,吹填土由液体泥浆变为固态土体,其孔隙降低非常大。由于土体的渗透性和压缩性是孔隙比的函数,因此,吹填土在固结过程中固结系数变化很大,而现行设计方法中固结系数取为常数,这导致预测结果和实际结果差异较大。为考虑固结过程中孔隙变化对固结过程的影响,推导了真空荷载作用下土体固结系数与有效应力的关系,并将该关系应用于巴隆固结理论,从而建立吹填土地基真空固结分析模型。通过室内模型试验,验证了该模型的合理性。计算结果表明,考虑孔隙变化的影响时,吹填土地基前期固结速度快,而在后期逐渐变慢。由于排水面附近土体渗透系数迅速降低,阻碍了周围土体中孔隙水向排水面排出,因此,与现行固结设计方法计算结果相比,吹填土地基后期固结速度慢,总体固结时间长。     

干湿循环作用对堆石长期变形影响的试验研究

堆石体存在流变,不仅与荷载有关,而且与日晒雨淋引起的干湿循环有关。通过室内试验模拟日晒雨淋引起的干湿循环作用,研究其对堆石体长期变形的影响。试验结果表明,荷载作用流变很快趋于稳定,测得的流变量也相对较小;偏应力状态干湿循环作用引起的长期变形非常明显,其变形占后期变形总量的50%~70%,且后期变形的衰减远小于荷载单独作用引起的流变,这对于坝体的安全和稳定的影响是不容忽视的。根据试验研究揭示的变形规律,本文建立了相应的计算干湿循环变形的数值模型,可用于有限元计算。     

山东省天然饰面石材花岗石和大理石地质特征及其分类

山东省天然饰面石材资源储量大,天然饰面石材品种多,地质成因和地质特征各有不同。通过天然饰面石材的岩石学特征对山东省天然饰面石材进行分类总结,从天然饰面石材的岩石学和矿物学角度出发,归纳山东省天然饰面石材的地质特征。通过对山东省典型天然饰面石材进行分类列举,归纳山东省典型天然饰面石材的地质特征。     

青岛市崂山风景区崩塌地质灾害治理方法探讨——以大平岚崩塌人造景观石治理为例

青岛市崂山风景区旅游主线大平岚附近发生崩塌地质灾害,导致崂山风景区南线道路全线封闭,崩落巨石上方的残留危岩体存在严重安全隐患,急需治理。为使原有景观石得以保护,又不致于形成新的视觉污染,利用人造景观石在崂山风景区大平岚崩塌地质灾害治理工程中进行了探索。实践证明,该方案投资少、工期短、效果好,既消除了崩塌地质灾害隐患,使原有景观石得到了保护,又未形成新的视觉污染,为人造景观石在风景区地质灾害治理工程中的应用起到了示范作用。     

陡坡寺中微风化料的大型三轴试验研究

随着西部山区的基础设施建设进入迅速发展的阶段,越来越多的高填方工程正在或将要兴建,而对填料力学性质的认识也就成为决定这些高填方工程安全性的重要因素。通过一系列大型三轴试验,对分布于云南等地的陡坡寺中微风化料的剪切力学特性进行了研究。结果表明,陡坡寺中微风化料与典型堆石料的力学特性有很大不同,其强度较低,并且应力-应变关系、强度和刚度等特征都比较接近于细粒土。另外,水对陡坡寺中微风化料的力学特性有着显著的影响,其遇水后强度大为降低,因此,在设计和施工中必须予以充分考虑。对试验数据的拟合表明,邓肯-张模型能较好地模拟陡坡寺中微风化料在不同围压下的应力-应变关系。     

Impact of draining hilly lands on runoff and on‐site erosion: a case study from humid Ethiopia

The use of drainage ditches on farmland has an impact on erosion processes both on‐site and off‐site, though their environmental impacts are not unequivocal. Here we study the runoff response and related rill erosion after installing drainage ditches and assess the effects of stone bunds in north Ethiopia. Three different land management systems were studied in 10 cropland catchments around Wanzaye during the rainy season of 2013: (1) the exclusive use of drainage ditches (locally called feses), (2) the exclusive use of stone bunds, and (3) a mixture of both systems. Stone bunds are an effective soil and water conservation technique, making the land more resistant against on‐site erosion, and allowing feses to be installed at a larger angle with the contour. The mean rill volumes for the 10 studied cropland catchments during the rainy season of 2013 was 3.73 ± 4.20 m³ ha^?1 corresponding to a soil loss of 5.72 ± 6.30 ton ha^?1. The establishment of feses causes larger rill volumes (R = 0.59, N = 10), although feses are perceived as the best way to avoid soil erosion when no stone bunds are present. The use of feses increases event‐based runoff coefficients (RCs) on cropland from c. 5% to values up to 39%. Also, a combination of low stone bund density and high feses density results in a higher RC, whereas catchments with a high stone bund density and low feses density have a lower RC. Peak runoff discharges decrease when stone bund density increases, whereas feses density is positively related to the peak runoff discharge. A multiple linear relation in which both feses and stone bund densities are used as explanatory variable, performs best in explaining runoff hydrograph peakedness (R² = 83%). Copyright © 2015 John Wiley & Sons, Ltd.