Long-term immobilisation of Cd2+ at the Tulul Al Hammam natural analogue site,central Jordan

The Tulul Al Hammam area in central Jordan is a natural analogue site where to study long-term Cd²⁺ retention during the weathering of Cd-enriched combustion-metamorphic marbles with clinker-like mineralogy. Natural Cd-rich portlandite (Ca_0.67−0.45Cd_0.33−0.55)[OH]₂ was discovered and characterised by single-crystal XRD, SEM/EDS, and microprobe analyses, and Raman spectroscopy. The Ca[OH]₂ – Cd[OH]₂ solid solution ((Ca_1−xCd_x)[OH]₂) is isostructural with Ca[OH]₂ and β-Cd[OH]₂ crystals in the CdI₂-type of structure. Cd-rich portlandite is a common secondary phase in slightly altered massive marbles, where it replaces and rims single-crystals of the high-temperature precursor (Ca_1−xCd_x)O. The Cd:Ca molar ratios of (Ca_1−xCd_x)[OH]₂ are inherited from the precursor phase (Ca_1−xCd_x)O. Reliable long-term immobilisation of Cd in (Ca_1−xCd_x)[OH]₂ is assumed for pore water pH values from 10.5 up to 12 buffered by C-S-Hs formed mainly during spurrite hydration. The Tulul Al Hammam site may have some bearing on long-term Cd²⁺ retention in the concrete matrix.     

天山公路独山子至乔尔玛段冻土特征及其灾害初探

独山子至乔尔玛段公路位于天山达坂海拔较高处,沿线多种冻害(包括热融滑塌、冻胀、冻融泥流及路基融沉等)经常发生,随着整治改建工程的实施,逐渐改变了地气热交换的界面,多年冻土原有的水热平衡遭到了破坏,其结果是通过路基进入多年冻土的热收支呈正平衡发展趋势,积热作用导致了路基下多年冻土的融化,将会引起公路的融化下沉,冻土灾害将趋于严重,本文初步探明了该公路沿线多年冻土的特征,提出了施工和运营中应采取保护冻土的设计原则.     

红山窑红砂岩膨胀变形和软化特性试验研究

以南京红山窑水利枢纽工程所提供的基岩红砂岩岩芯为例，采用MTS815．02型岩石刚性伺服试验系统和岩石膨胀测量仪，对风化红砂岩进行膨胀变形及力学特性试验研究。试验结果表明：红砂岩膨胀应变随吸水率增加而呈对数增长，红砂岩弹性模量、抗压强度随吸水率增加而呈对数减小，而泊松比随吸水率增加而呈对数增大，由于含水率的变化使膨胀岩发生了显著的软化现象。研究成果为工程地基稳定性分析提供了可靠的理论依据。     

充分利用地质档案优选水泥原料矿山

优选云南水泥原料矿山,对水泥工业持续发展有重要意义。根据多年从事地质档案管理经历,充分利用、发掘地质档案资源信息,整理、研究、统计了云南水泥原料矿产资源的分布状况,优选部分水泥原料矿山,为本省水泥原料矿产资源规划、水泥工业持续发展和投资决策服务。     

Effect of swelling inhibitors on the swelling and stress relaxation of clay bearing stones

Clay-containing stones such as Portland Brownstone (USA), Villarlod Molasse (Switzerland) and Tarifa Sandstone (Spain), are expected to weather as a result of wetting and drying cycles. During drying events, contraction of the drying surface leads to stresses approaching the tensile strength of the stone. However, we have found that the magnitude of these stresses is reduced by the ability of the stone to undergo stress relaxation. In this paper we describe novel methods to determine the magnitude of the stresses and the rate at which they develop and relax. We also discuss the influence of swelling inhibitors on the magnitude of swelling and the rate of the stress relaxation of these stones. The implications of our findings for the understanding of damage due to swelling of clays are discussed.Special Issue: Stone decay hazards     

Evaluating the stiffness of chemically stabilized marine clay

Cement-stabilized clay is widely used in soft clay improvement for deep excavation, underground construction, and land reclamation. This paper presents a study on the evaluation of elastic modulus for cement-stabilized marine clay. First, two types of cement-stabilized soils were studied through isotropic compression tests and cylinder split tensile tests. Specimens with different mix ratios and curing periods were used. Stress–strain behavior under isotropic compression was discussed, followed by an introduction and estimation of the stress-free bulk modulus. Empirical correlations between elastic moduli and functions for estimating elastic moduli were then proposed. Further estimation of elastic modulus was conducted with another data set. The results showed that the proposed function for estimating elastic modulus is effective for cement-improved marine clay. Finally, the proposed method and empirical functions were validated with other types of cement-stabilized clay.     

干湿-冻融循环下延吉膨胀岩的力学特性及其应力-应变归一化

为了研究干湿、冻融和干湿-冻融循环作用对延吉膨胀岩的应力-应变关系、体变特性、抗剪强度的影响,开展了一系列的固结排水剪切试验。结果表明：未循环试样的应力-应变关系曲线表现为稳定型或弱应变软化型,3种环境作用后试样应力-应变关系曲线呈现出一定的应变软化特性,剪胀明显,而且围压越小、循环次数越高的试样软化和剪胀的程度越高;随着循环次数的增加,3种环境作用下试样的黏聚力急剧减小,而内摩擦角略有增加;干湿-冻融循环作用下试样的应力-应变关系软化程度最高,剪胀最显著,试样的黏聚力降低的幅度最大。基于Konder双曲线模型,对循环处理前后试样的应力-应变特性进行归一化分析,建立了考虑干湿-冻融循环次数和围压影响,能同时描述应变软化型和硬化型的应力-应变关系式,并对不同干湿-冻融循环次数试样的应力-应变曲线进行预测,预测值与实测值较为接近,预测效果较好。     

密实砂-膨润土混合物膨胀特性的试验研究

密实砂－膨润土混合物作为高放废料地质处置的缓冲材料,人们来越来关心它的性质。通过大量的试验,研究了密实砂－膨润土的膨胀特性,阐明了其膨胀过程和方式,得出了一步有意义的结论。     

中国水泥行业节能减排措施的协同控制效应评估研究

水泥行业是温室气体与局地污染物协同控制的重点行业。以往该行业的协同控制评估或针对个别企业,或采用自上而下和自下而上模拟模型结合情景分析评估行业协同减排效益,尚缺乏系统评估水泥行业全系列节能减排措施（或技术）协同控制效果的研究。文中首先测算水泥行业24项节能减排措施综合大气污染物协同减排量,再通过协同控制效应坐标系、交叉弹性、单位污染物减排成本等评估指标和方法,对这些措施开展协同控制效果评估。结果表明大多数节能减排措施可协同减排局地大气污染物;协同减排潜力最大的是结构调整措施;能效提升与节能措施的协同减排成本较低,但减排潜力有限。本文强化了水泥行业节能减排措施的协同控制效能特性分析,可为水泥行业开展协同控制路径规划提供参考。     

膨胀变形对膨胀土边坡稳定性的影响

当采用合理的强度参数时,根据常规极限平衡或极限分析方法的计算结果,很难解释一些膨胀土边坡会在极缓的坡度下发生失稳破坏的原因。事实上,由于膨胀土遇水后会发生显著的变形,在饱和区与非饱和区交界面附近会出现很大的剪应力。因此,在膨胀土边坡的稳定分析中,需要考虑这种因素的影响。根据塑性力学的上限定理,严格地导出了考虑膨胀应力作功的功能平衡方程。根据强度储备定义的安全系数即隐含在这一方程中,它可以通过迭代方法求解。边坡稳定的上限分析在数值上是利用了单元集成法来完成的。这不仅能方便地利用应力分析的成果,而且能进行滑裂面的优化,从而找到最小的安全系数。对一个坡度为1:4的膨胀土边坡的稳定计算结果表明,膨胀变形会使边坡的安全系数显著减小。当考虑膨胀时,优化得到的破坏模式是在浅层出现一个局部的滑动,它会牵动其上部的土体也相继出现局部滑动,这正好符合膨胀土滑坡时所常见的牵引性的特征。