K0固结条件对上海软土强度和变形影响的试验研究

本文通过对上海淤泥质粉质粘土和淤泥质粘土,在K_0固结条件下的常规三轴和真三轴排水剪切试验,探讨了K_0固结状态对上海软土强度和变形性能的影响规律,并与各向等压固结三轴排水剪切试验的情况进行了比较和分析。     

水下爆破技术在加固湿陷性黄土地基中的应用

分析了在湿陷性黄土区域，水下爆破技术在加固湿陷性黄土地基中的设计与实施。     

BEM analysis of elastic foundation beams on multilayered isotropic soils

This paper presents a boundary element method to analyze the elastic foundation finite beams on 2D plane-strain and 3D multilayered isotropic soils. Starting with the basic equations of elasticity and based on the Fourier transform, the transfer matrix of a single soil layer is derived. According to the boundary conditions and continuity conditions between two adjacent soil layers, the solution of multilayered elastic soils is obtained to be a kernel function of BEM analysis. The elastic foundation beam is modeled as a Bernoulli–Euler beam using the finite difference method. With the displacement and stress condition of coordination between beam and soil, the solution is acquired for beams resting on multilayered soils. Comparing the solution with the published data shows that the solution is in good agreement, and some numerical examples show that the beam behavior is affected vitally by soil–beam stiffness ratio and the stratification of soils.     

Failure behavior and mechanism of slopes reinforced using soil nail wall under various loading conditions

Soil–nailing technology is widely applied in practice for reinforcing slopes. A series of centrifuge model tests was conducted on slopes reinforced with a soil nail wall under three types of loading conditions. The behavior and mechanism of failure process of the reinforced slopes were studied using image-based observation and displacement measurements for the slope, nails, and cement layer. The nailing significantly increased the stability level and restricted the tension cracks of the slopes. Increasing the nail length improved the stability of the reinforced slopes with deeper slip surfaces. The reinforced slope exhibited a significant failure process, in which slope slippage failure and cement layer fracture occurred in conjunction with a coupling effect. The deformation localization was induced by the loading within the slope and ultimately developed into a slip surface. The nailing reinforced the slope by significantly delaying the occurrence of the deformation localization within the slope. The failure of nails was recognized as a combination of pull-out failure and bend deformation. The loading conditions were shown to have a significant effect on slope deformation and nail deflection, and they consequently influenced the failure behavior and its formation sequence.     

杭州城西软土工程特性分析

通过对杭州城西软土土性物理力学指标的统计分析,研究了土性沿深度的变化情况,分析了城西软土的工程特性,总结了城西软土对工程建设的主要危害,为该地区工程建设提供一定理论依据及经验参考。     

Influence of phosphorus on Cu sorption kinetics: stirred flow chamber experiments

A stirred flow reactor was used to study the influence of phosphorus on the adsorption and desorption kinetics of copper in two acid soils on granite and amphibolite. The presence of P was found to significantly increase Cu adsorption in both soils, albeit at different types of sites (mainly in slow adsorption sites in the soil on granite, and both in fast and slow adsorption sites in that on amphibolite). The increased Cu sorption at fast sites in the amphibolite soil was due to its high content in Fe oxyhydroxides, which bound P and released OH(-) as a result, thereby raising the pH and leading to a higher sorption capacity during fast reactions. On the other hand, the increased Cu sorption at slow adsorption sites was due to Cu(2+) acting as a bridging element between P and organic matter.     

非饱和土地基的三维非轴对称动力响应

考虑土颗粒、孔隙流体的压缩性以及各相物质间的黏性、惯性耦合,采用Bishop有效应力公式和毛管压力函数的V-G模型,建立了非饱和土的动力控制方程.通过引入位移函数,并利用Cauchy-Reimann条件,在直角坐标系下将非饱和土的波动方程进行解耦,进而采用双重Fouricr变换,求得了位移和应力在变换域上的一般解.结合...     

复杂条件下某深大基坑支护结构优化设计

某大型深基坑位于湖北荆州市中心城区,地处长江Ⅰ级阶地,距离有地上悬河之称的长江荆江干堤仅700m,基坑开挖深度达8．0m,基坑重要性等级为一级。地层软弱,孔隙潜水和承压水非常丰富,周边环境安全性要求高,对基坑设计提出了很高的要求。通过理论分析和经验判断,针对各段地层和基坑轮廓形状,优化设计了灌注桩和一道钢管内支撑支护、门式刚架支护、圆拱形支护设计等支护结构。工程实践表明,因地制宜的支护结构设计既能最大限度地方便基坑开挖施工,又能很好地控制周边的沉降和差异沉降,为复杂环境地质条件下深基坑工程的设计、施工提供了宝贵的经验。     

In vitro digestion and DGT techniques for estimating cadmium and lead bioavailability in contaminated soils: influence of gastric juice pH

A sensitivity analysis was conducted on an in vitro gastrointestinal digestion test (i) to investigate the influence of a low variation of gastric juice pH on the bioaccessibility of Cd and Pb in smelter-contaminated soils (F_B, using the unified bioaccessibility method UBM) and fractions of metals that may be transported across the intestinal epithelium (F_A, using the diffusive gradient in thin film technique), and (ii) to provide a better understanding of the significance of pH in health risk assessment through ingestion of soil by children. The risk of metal exposure to children (hazard quotient, HQ) was determined for conditions that represent a worst-case scenario (i.e., ingestion rate of 200 mg day^− 1) using three separate calculations of metal daily intake: estimated daily intake (EDI), bioaccessible EDI (EDI-F_B), and oral bioavailable EDI (EDI-F_A). The increasing pH from 1.2 to 1.7 resulted in: (i) no significant variation in Cd-F_B in the gastric phase but a decrease in the gastrointestinal phase; (ii) a decrease in soluble Pb in the gastric phase and a significant variation in Pb-F_B in the gastrointestinal phase; (iii) a significant decrease in Cd-F_A and no variation in Pb-F_A; (iv) no change in EDI-F_B and EDI-F_A HQs for Cd; (v) a significant decrease in EDI-F_B HQs and no significant variation in EDI-F_A HQ for Pb. In the analytical conditions, these results show that risk to children decreases when the bioavailability of Pb in soils is taken into account and that the studied pH values do not affect the EDI-F_A HQs. The present results provide evidence that the inclusion of bioavailability analysis during health risk assessment could provide a more realistic estimate of Cd and Pb exposure, and opens a wide field of practical research on this topic (e.g., in contaminated site management).