深层搅拌桩复合地基的现场试验研究

结合雍六高速公路长江二桥江北接线工程 ,对填土荷载下复合地基的应力、变形特性进行了长期现场观测研究 .结果表明 :路基经深搅桩加固后 ,沉降变形得到有效控制 .加固区沉降量较小 ,下卧层沉降量较大 ,总沉降量满足设计及规范的要求 ;柔性路堤下桩与桩间土的沉降规律有差别 ,桩身上部桩周土沉降较大 ,随着深度增加 ,桩周土沉降逐渐小于桩的沉降 ,在这个过程中 ,桩与桩周土存在等沉面 ;在填土加荷过程中 ,桩与土各自分担的应力处在动态的变化之中 :加荷时 ,桩上应力相对集中 ;间歇期 ,桩土应力比减小 ;体现了荷载传递过程中桩与土是相互协调作用的     

沪芦高速公路软土地基设计与研究

软土地基的处理是影响高等级公路工程质量和使用性能的重要因素 ,针对沪芦高速公路的工程特点 ,通过对不同土层力学性能分析 ,地基稳定验算以及沉降计算提出地基处理方案 ,并介绍通过地基处理后获得的显著效果     

黑土土壤质量演变初探I：不同开垦年限黑土主要质量指标演变规律

根据土壤质量的定义和研究方法 ,对黑土的主要质量指标演变规律进行初步研究。结果表明 :黑土的颗粒组成受开垦历史影响的程度较小 ,其质地没有发生显著变化 ;黑土的有机质、全氮、全硫和全磷随着黑土开垦时间的增加而不断降低 ;速效磷随黑土开垦时间的增加有增高的趋势。经过统计分析 ,黑土中粉砂(0.05～0.002mm)含量与细砂(0.25～0.05mm)和粘粒(<0.002mm)含量具有相关性,黑土有机质含量与全氮、全硫、全磷和速效钾具有明显的正相关。因此 ,初步认为黑土中粉粒和有机质含量可以作为土壤物理和养分方面的质量指标     

Electroclinic measurement of the coefficients of Landau expansion of some ferroelectric liquid crystals

The electroclinic effect in the smectic A phase of ferroelectric liquid crystals is a sensitive probe for measuring the soft mode response near the A-C* transition point. It is possible to evaluate several coefficients of the Landau theory describing the A-C* transition by simultaneously measuring the frequency dependence of both the optical signal and the current through the sample. We have made such measurements on a couple of homologous series [2S,3S]-4′-(2-chloro-3-methyl pentanoyloxy) phenyl-trans-4″-n alkoxy cinnamates synthesized in our labortory. The results show that the Landau meanfield theory is adequate to describe the A-C* phase transition in these compounds. Presented at the 15th International Liquid Crystal Conference, Budapest, 3–8 July 1994.     

松嫩平原洪涝旱碱综合治理及水土资源可持续利用问题

文章依据松嫩平原洪、涝、旱、碱综合治理和在水土资源中存在的问题，提出必须加大科研力度，提高技术含量，从保护生态环境可持续开发利用自然资源的战略角度出发，综合治理洪、涝、旱、碱灾害，并提出了一些具体作法。     

构皮滩水电站尾水隧洞特大断面软岩开挖支护

构皮滩水电站尾水隧洞软岩不良地质洞段占尾水隧洞全长的70%以上,确保软岩洞段的安全快速开挖是尾水隧洞施工的关键,尤其一次支护的强度对洞室稳定影响极大。为此,施工中根据软岩的地质特点及尾水隧洞开挖的断面尺寸,采取分层开挖和超前锚杆的施工方式和型钢拱架进行一次支护。根据监测结果,围岩变形很小,一次支护效果良好,表明构皮滩水电站尾水隧洞大断面软岩采取的开挖方式和一次支护方式是成功的。     

Predicting plant yields using soil testing for phosphorus: Effects of error in the estimation of the maximum yield on interseasonal comparisons of yield prediction

Results from long-term field experiments in south-western Australia are presented in the form of relationships between yield, expressed as a percentage of the maximum yield, and soil test for phosphorus (P) values. Maximum yields were not always indicated by well defined yield plateaux. Different methods have been used to estimate the maximum yield value which is used to calculate yield as a percentage of the maximum yield so as to remove interseasonal variation. For all of these methods and for the same site, the same P fertilizer (superphosphate), and the same plant species, the relationship between yield and soil test P differed for different years. Consequently fertilizer recommendations based on the assumption that this relationship is constant are likely to be incorrect. We therefore question the validity of the common practice in soil testing programmes of using percentage yield values to remove interseasonal variation.     

渭河流域水利水保措施减水减沙效益初步分析

截止1989年底,渭河流域共有水库361座,塘坝2666座,引水有效灌溉面积40.4万公顷,治理总面积8136km~2,治理度17.1％。以1970年为效益计算起始年,并将全流域划分为18个片,分别采用水文法和水保法计算1970～1989年间各项水利水保措施减水减沙量及综合减水减沙效益。水文法算得的综合减水效益为24.1％,减沙效益为30.6％;水保法算得的结果相应为29.9％和30.8％,两者相近。     

Evaluating Liquefaction Strength of Partially Saturated Sand

A method is presented for evaluating the liquefaction strength of partially saturated sand using the compression wave velocity (P-wave velocity), a new indicator of saturation. Based on laboratory test results, an empirical correlation that relates the liquefaction strength with the pore pressure coefficient B is firstly proposed. The strength is defined as the cyclic stress ratio required to cause liquefaction at a specified number of cycles. With the aid of a theoretical relation between B and the P-wave velocity, an explicit correlation of more interest is then established between the liquefaction strength of sand and its P-wave velocity. A comparison of the predictions using this explicit correlation with laboratory measurements shows a satisfactory agreement. The significance of this method lies in that it makes it possible to evaluate the liquefaction strength of sand as affected by saturation through the measurement of P-wave velocity, which can be made not only in the laboratory but particularly in the field.     

海洋软管增强层的选择及结合方式

当前输油管道软管的应用越来越广，尤其是陆上石油开采日趋贫乏，海庆石油开采比重将越来越大，势必将对海洋用软管的需求不断加大。而对海洋软管技术要求也不断提高，其中大多是针对软管内的增强层所提出的。论述了海洋软管增强层的结构形式、技术要求、材质选择等几方面内容，考察了不同增强层对海洋软管耐压性、耐蚀性、屈挠性、粘合性等指标的影响。