深基坑降水方案的确定

结合具体工程实例,介绍了基坑降水方案的选择,进行了基坑降水设计计算,阐述了防渗帷幕的设置和回灌系统的布置,提出了基坑降水施工的建议,积累了深基坑降水经验。     

南京德基广场井点动态降水施工技术

根据南京德基广场二期工程超深逆作法基坑降水的施工实践,结合地下结构逆作法施工部署,围绕逆作法深基坑降水的降水设计和施工运行等关键问题进行重点分析与阐述.该工程降水施工与运行历经2年多,直至工程地下逆作法施工结束,期间基坑外围环境各项变形监测数据稳定,土方和结构施工进展顺利,表明超深逆作法基坑分层按需式井点动态降水科学、...     

西安地铁五路口车站基坑降水设计

以西安地铁五路口站深基坑降水工程为例,结合工程地质及水文地质条件,确定基坑降水的设计参数,介绍了深基坑降水的计算方法和设计方案,总结了降水施工时应考虑的因素以及工程主要施工技术要点,从而为类似的工程积累经验。     

浅谈高层建筑深基坑坑内降水方案设计

以西安市某高层建筑深基坑工程为例,结合工程地质及水文地质条件,确定基坑降水的设计参数,给出深基坑降水合理的计算方法、设计方案以及施工技术要点,以达到降水目的,实现工程施工的顺利完成,并为类似的工程提供相关的经验。     

某厂基坑工程降水设计

对某项目的基坑工程进行降水设计,利用管井井点降水,用Dupuit公式对基坑的涌水量进行计算,同时确定井点数量以及对降水井井位进行合理布置,并对基坑内水位降深进行了验算和降水时间进行预测,可供相关工程参考。     

某高层建筑深基坑工程降水方案研究

以阳光新城居民小区基坑工程为背景,结合场区工程地质及水文地质条件,确定基坑降水的影响半径及场区综合渗透系数参考值,在此基础上采用管井井点降水方法进行降水工程的设计计算。综合拟建建筑平面布置情况及基坑开挖深度的不同,建立完整潜水井模型分区进行了降水井的设计计算及降水系统的布置设计。验算结果表明:各系统井点数量及井点间距均能够满足相关规范及工程降水要求,可以保证基坑及基础施工安全。降水工程采用封闭矩形井点系统同双排井点系统相结合的管井井点降水方案,安全可靠,经济合理,可为该地区类似基坑降水工程提供指导。     

基坑工程降水方法及其优化分析

基于济南西客站站前广场基坑工程地质、水文地质条件,要求基坑降水避免对邻近京沪高铁路基产生不利影响,采用高压摆喷止水帷幕、基坑管井降水、坑外回灌等降水设计方案。设计无止水帷幕和5种不同深度的止水帷幕等6种工况,采用有限差分软件对基坑降水全过程进行渗流模拟,得到不同工况的降水漏斗曲线。通过降水影响范围、及坑外最大降深,对止水帷幕优化分析,设计止水帷幕深24 m。工程实践证明本基坑降水方案设计是合理的,可以为周边基坑降水方案设计提供参考。     

超高层建筑深基坑降水施工技术分析

本文结合某五星级酒店工程基坑降水施工技术方案进行了介绍,分别阐述了降水设计方案,基坑围护设计,施工工艺流程,以期为今后类似基坑降水提供参考。     

某地铁站深基坑降水施工设计

以某地铁站深基坑降水工程为例,介绍了深基坑降水设计方案,包括设计参数计算选择,降水对周围环境的影响及其防范措施,降水施工时应考虑的因素以及结合这些因素该工程主要施工技术要点.     

深基坑降水对周边环境产生影响的主要因素分析

结合天津市某地铁深基坑工程实例，对在深基坑降水过程中对周边环境产生影响的主要因素进行分析探讨，提出了深基坑降水应注意的问题。     

The chemistry of precipitation in relation to precipitation type

Collections have been made of several types of wet deposition and of aerosols in various particle size ranges. The chemical composition of the precipitation changes significantly from one precipitation type to another. The forms of deposition, diffusionally-grown ice for example, compared with accretionally-grown ice, appear to be important factors controlling the concentrations and ratios of the several elements which have been measured.The aerosol samples show significant changes in chemical composition with particle size, consistent with other observers' results. It is hypothesized that these changes in aerosol chemistry and those of the wet deposition are related, and that this information, combined with the theoretically supported processes of nucleation, Brownian capture, phoretic processes and impaction, provide a better insight to the physical processes involved in the removal of chemical impurities from the atmosphere.     

EMD-RBF的GPS可降水量的降水预报方法综述

综述了近几年的降水预报模型,分析比较了几种模型的特点,并提出了基于经验模态分解的神经网络降水预报模型,以提高GPS可降水量的降水预报在气象业务的短期天气预报中的应用水平。     

微生物诱导碳酸镁沉淀试验研究

碳酸镁和碳酸钙一样也具有胶结作用,且镁矿强度远大于钙矿,因此研究碳酸镁固化技术具有重要意义。本文测量了巴氏芽孢杆菌在培养过程中的吸光度和脲酶活性,并计算得到单位脲酶活性;研究了尿素、氯化钠、醋酸根、Ca2+和Mg2+浓度对脲酶活性的影响;控制温度、pH值和离子浓度对比了钙和镁沉淀效率和不同温度不同尿素浓度下碳酸镁沉淀产率;对比研究了碳酸钙和碳酸镁沉淀下砂土固化效果。结果表明,48 h培养过程中,吸光度和脲酶活性的增长都先缓慢后迅速增长再减小最后停止,单位脲酶活性则是先增加后减小。适当增加尿素或Mg2+浓度可增强细菌脲酶活性,氯化钠和醋酸根浓度对酶活性无明显影响,Ca2+浓度对脲酶活性有明显抑制作用。同一温度、pH值和离子浓度条件下,碳酸镁产率明显小于碳酸钙。而在菌液中添加尿素可促进碳酸镁沉淀生成,且温度相同,尿素浓度越高,碳酸镁产率越大。菌液中添加尿素可使得碳酸镁固化砂土成型并具有一定强度,因此,该方法可解决砂土固化碳酸镁沉淀不足的问题,为后续碳酸镁固化试验奠定基础。     

Legal aspects of acidic precipitation

Acid rain has been discovered to be a serious problem in Eastern Canada. The legislative competence of the Federal Parliament to deal with air pollution is not well established, but recent cases interpreting the federal general power indicate that the scope of general power has been established. Canadian common law remedies are not likely to be successful, for a variety of reasons. The Canadian Clean Air Act, especially with the 1980 amendments lays the basis for possible adoption of emission standards for acid rain as an international pollutant. Ontario's Environmental “ Protection Act of 1971 may offer a basis for control of emissions resulting in acid rain though regulation of major sources and control orders of medium sized and small sources. One such regulation has already been adopted to apply to the Inco Plant emissions of sulfur oxides.     

Magnetite seeded precipitation of phosphate

Seeded precipitation of Ca phosphate on magnetite mineral (Fe3O4) surfaces was investigated using a Jar Test system in supersaturated solutions at 20 degrees C and ionic strength 0.01 mol l(-1) with relative super saturation, 12.0-20.0 for HAP. pH of the solution, initial phosphorus concentration and molar Ca/P ratio were investigated as the main parameters, which effect the seeded precipitation of Ca phosphate. Results showed that there is no pronounced effect of magnetite seed, neither positive nor negative on the amount of calcium phosphate precipitation. pH was found to be the main parameter that determines the phosphate precipitated onto the seed surface. Increasing of the pH of precipitation reaction was resulted in the decrease in percentage amount of phosphate precipitated onto seed surfaces to total precipitation (magnetite seeded precipitation efficiency). It was concluded that the pH dependence of magnetite-seeded precipitation should be considered in the light of its effect on the supersaturated conditions of solution. Saturation index (SI) of solution with respect to the precipitate phase was considered the driving force for the precipitation. A simulation programme PHREEQC (Version 2) was employed to calculate the Saturation-index with respect to hydroxyapatite (HAP) of the chemically defined precipitation system. It was found a good relationship between SI of solution with respect to HAP and the magnetite seeded precipitation efficiency, a second order polynomial function. Results showed that more favorable solution conditions for precipitation (higher SI values of solution) causes homogenous nucleation whereas heterogeneous nucleation led to a higher magnetite seeded precipitation efficiency.     

井点降水施工实践探索

通过对井点布置原则、井点管的埋设、井点结构施工的技术要求等方面详细地阐述了井点降水的施工工艺,并提出了井点系统的使用注意事项,最后就控制井点降水对周边环境危害的措施进行了研究。     

浅析引渗井降水施工

阐述引渗井降水施工的适用范围，分析了引渗井降水施工的原理，详细介绍了引渗井的施工方法，提出了异常水处理措施，归纳了引渗井降水方法的优点，为基础工程施工降水提供了一种全新的施工方法。     

某工程降水设计

介绍了该工程的概况及场地水文地质条件。因受场地条件限制，多级井点降水困难而采用管井方式降水。阐述了降水井布设的设计依据与原则，井孔平面布设与结构设计及其施工方法，措出井孔对周边的影响及处理措施。并要注意合理布设观测点，科学选用水文地质参数，以达到良好的降水效果。     

Struvite precipitation thermodynamics in source-separated urine

Struvite (MgNH(4)PO(4).6H(2)O) precipitation eliminates phosphate efficiently from urine, a small but highly concentrated stream in the total flux of domestic wastewater. Precipitation experiments with hydrolysed urine evaluated the solubility product of struvite. The stored and fully hydrolysed urine had an ionic strength of between 0.33 and 0.56M and required the estimation of activity coefficients. From our data, we identified the Davies approximation with the two constants A=0.509 and B=0.3 as agreeing best with our laboratory results. The standard solubility product K(s)(0)=f(1)[NH4(+)]f(2)[Mg2+]f(3)[PO(4)(3-)] ([ ]=concentration of the species; f(x)=corresponding activity coefficient) of struvite in urine was found to be 10(-13.26+/-0.057) at 25 degrees C and the enthalpy of struvite formation DeltaH was 22.6(+/-1.1) kJmol(-1). The equilibrium calculations required the following dissolved complexes: [MgCO(3)](aq), [MgHCO(3)](+), [MgPO(4)](-), [NH4HPO4and [NaHPO(4)](-) and to a lesser extent [MgSO(4)](aq) and [NH(4)SO(4)](-). Organic complexes do not seem to influence the solubility product substantially. For practical purposes, a conditional solubility product K(s)(cond)=[Mg(aq)].[NH(4)(+)+NH(3)].[P(ortho)]=10(-7.57)M(3) was derived to calculate struvite solubility in urine at 25 degrees C, pH=9.0 and ionic strength I=0.4M directly from measured concentrations.     

降水与回灌技术的应用

结合具体工程实例,探讨了降水与回灌技术的应用,提出了针对技术难题制定的措施,阐述了该基坑工程的组织实施,观测结果表明,该工程在基础开挖及降水过程中没有对相邻建筑物的沉降产生不良影响。