Vertical cyclic loading response of geosynthetic-encased stone column in soft clay

Dynamic responses of the geosynthetic-encased stone column (GESC) supported embankment under traffic loads have become a hot topic. This study investigates the responses of GESC improved ground under vertical cyclic loading. A series of laboratory tests in a designed model test tank have been carried out with different loading parameters (varied loading amplitudes and frequencies), different column dimensions (varied encasement lengths and column diameters). In the tests, the soil-column stress distribution, accumulated settlement of loading plate, excess pore water pressure in the surrounding soil and lateral bulging of the stone column are monitored. Experimental results indicate that the vertical stress on the stone column increases with the increment of encasement length, and decreases with the increment of column diameter, loading amplitude and loading frequency. The increasing stress on the surrounding soil leads to a greater accumulated settlement of the loading plate and excess pore water pressure, while the increasing stress on the column leads to larger lateral bulging of the column. Excess pore water pressure dissipates effectively through vertical and horizontal drainage channels provided by the stone column and the sand bed. The geosynthetic encasement prevents the clay from obstructing the drainage channel by filtration and guarantees the drainage effect.     

全尾砂和废石联合胶结充填体最佳配比及应用

针对红岭铅锌矿分级充填骨料来源不足、地表废石堆积污染环境的情况,提出将该矿选厂产生的全尾砂和地表废石作为充填骨料的联合胶结充填方案。分别测试了全尾砂和地表废石的物理化学性质,验证了碎石和全尾砂作为联合充填骨料的可行性。通过充填配比试验,分析了不同配比全尾砂废石充填体强度特性,得出了最佳充填配比。结果表明,充填试块的强度随灰砂比减小而减小,随养护龄期增加呈增大趋势,随充填料浆质量浓度增大而增大,最佳配比为: 胶结充填灰砂比1∶8、普通充填灰砂比1∶12,全尾砂∶废石配比4∶6,质量浓度78%。根据研究结果,在红岭铅锌矿进行了全尾砂废石充填技术工业应用,证实该技术可行。     

酸性废水中As(Ⅲ)、Cu(Ⅱ)与铁粉的反应行为

在Fe-As(Ⅲ)-Cu(Ⅱ)-H₂O体系中, 研究了酸性废水中As(Ⅲ)、Cu(Ⅱ)与金属铁粉的反应行为, 考察了反应过程中As在气、液、固三相中的分配比。结果表明, As(Ⅲ)和Cu(Ⅱ)离子被Fe还原为单质As和Cu后, As、Cu进一步结合成Cu₅As₂等金属间化合物, 从而促进As(Ⅲ)沉淀反应的发生, 且无AsH3生成。在反应时间40min、铁粉过量系数1.2、溶液初始pH=0.0、温度40 ℃、Cu/As摩尔比1.0条件下, As在气、液、固三相中的分配比分别为0、20.7%和79.3%, 沉砷率为79.3%。     

Isolation of the effect of the hairy layer length on the mechanical properties of waterborne coatings

The effect of the acidic hairy layer length on the interdiffusion of polymer between particles and as a consequence on the mechanical properties of the films produced from waterborne coatings has been studied. In order to isolate this effect, latexes with the same particle diameter and molecular weight but stabilized with poly(acrylic acid)-block-poly(butyl acrylate) (PAA-b-PBA) block copolymers of controlled and different lengths were prepared. Tensile strength measurements showed at the macroscopic level that the presence of AA chains in the particle surface reduced the mechanical properties of the films dried at room temperature, being its effect worse the longer the AA chain length. Higher annealing temperatures erased the negative effect of the acidic hairy layer on mechanical properties. The neutralization with NaOH instead of with NH₄OH also led to worse mechanical properties. These macroscopic results were supported by Fluorescence Resonance Energy Transfer (FRET) experiments that showed that at the microscopic level, the extent of interdiffusion occurred slower when the AA chains in the particles surface increased, the annealing temperature was lower and when NaOH was used as neutralizing agent instead of NH₄OH.     

水力旋流器用于酸性油分离的研究

采用自行研制的水力旋流器进行了降低酸性油酸值的工业实验。实验表明,水力旋流器可将酸值为13．3 mgKOH/g的酸性油酸值降至12 mgKOH/g左右,从而能满足工业生产要求,沉降时间大为缩短。     

粗粒土渗透变形机制浅析

对砂卵砾石的渗透变形的形成条件进行了简要分析，在此基础上对渗透变形的形式进行了简要评价，并提出了渗透变形临界坡降的计算方法。     

80kt/a硫磺回收装置国产化设计

介绍了无在线炉硫回收工艺的基本原理、技术特点和催化剂使用情况。已投用的工业装置运行结果证明 ,用该工艺设计的硫磺回收装置 ,硫回收率和尾气净化度高 ,投资少 ,能耗低 ,流程简单 ,操作控制方便 ,社会效益和经济效益显著 ,适用于同类装置的新建和改扩建项目 ,市场前景广阔。     

西霞院水利枢纽工程泄洪闸振冲碎石桩基础处理

通过西霞院水利枢纽工程泄洪闸振冲碎石桩基础处理施工方法论述,给出了加砂层振冲碎石桩施工造孔水压、水量、成孔速度、填料级配、填料方法以及振密电流值、留振时间等施工控制参数。     

CO2泡沫压裂优化设计技术及应用

针对苏里格低压、低渗透气藏常规水基压裂液压后返排困难,导致储层水锁伤害的问题,研究利用CO2泡沫压裂来降低压裂液滤失,提高压裂液返排率,降低对储层的伤害。有针对性地研究了CO2泡沫压裂优化设计技术,包括:CO2泡沫压裂起泡技术、酸性交联技术、变泡沫质量和恒定内相设计技术等。现场应用表明,长庆苏里格气田气藏应用CO2泡沫压裂技术,可大大提高返排率,缩短压裂液返排时间,降低压裂液对气层的伤害,提高压裂效果。     

Finite-element analysis and experimental study on tensile fatigue behaviour of bitumen–stone adhesion

Tensile fatigue behaviours of bitumen–stone adhesion were investigated using a dynamic mechanics analyser under stress‐controlled mode at two temperatures of 5 and 25°C and various controlled‐stress levels. Failure characteristics including interfacial failure and cohesive failure were examined using image analysis of fracture surfaces. Finite‐element analysis on stress distributions was conducted under different temperatures, film thickness and interfacial bonding conditions. A Coulomb–Mohr like criterion in combination with shear and normal stresses is proposed to deal with the extreme thin adhesive layer, which can be further simplified into an adhesive zone without significant loss of accuracy for stress analysis.