基桩孔内摄像检测技术

福建省建筑科学研究院地基基础研究所承担研究的基桩孔内摄像检测技术适用于具有桩身竖向孔的预制桩（如PHC桩）或有竖向孔的灌注桩的完整性检测。具有直观、准确和能够对缺陷进行定量分析的优点，同时，可用于对多重缺陷、竖向缺陷、架用快速机械接头施工的管桩进行检测并可对采用钻芯法检测的灌注桩进行补充检测。该研究成果通过了省建设厅组织专家进行的技术评审，认为整体达到国内领先水平，具有广阔的市场应用前景。     

用水泥土引孔的静压PHC管桩竖向承载力的试验研究

对浅部有深厚密实砂层的静压PHC管桩的竖向承载力进行了系列试验研究,包括对常规静压桩分别进行静载和休止后复压静载试验、对用不同水泥土引孔工艺的8根静压PHC管桩进行竖向静载试验、对12根桩进行高应变动力测试等。研究结果表明,采用改进工艺的水泥土引孔技术能使桩基竖向承载能力大幅度提高,可有效减少桩长,节约费用,且压桩力显著降低,施工便捷。此外,低应变动载测试表明,桩身完整性良好、施工质量可靠。     

人工挖孔桩单桩竖向承载力可靠性分析

基于沈阳城区挖孔桩竖向承载力试计比的统计参数和无量纲随机变量的极限状态方程,对挖孔桩竖向承载力进行了可靠性分析;采用校准法计算了沈阳地区地基规范中挖孔桩的目标可靠指标,并分析了荷载效应比、荷载组合和抗力概型分布对可靠指标的影响。研究结果表明,挖孔桩竖向承载力标准值遵循对数正态分布,荷载效应比和荷载组合形式对可靠指标的影响较大,抗力概型分布对可靠指标有一定程度的影响,挖孔桩竖向承载力在不同的荷载组合下应采用不同的目标可靠指标。     

超流态混凝土钻孔压灌桩的应用分析

介绍了超流态混凝土钻孔压灌桩的工艺、技术特点及单桩竖向承载力标准值的估算 ,并与挖孔桩、筏板基础等其它桩型进行了技术、经济效益比较 ,说明了超流态混凝土钻孔压灌桩的优势     

某工程高强预应力管桩沉桩竖向裂缝原因分析及处理

某项目高强预应力管桩沉桩施工中遇到强风化泥岩中存在中风化夹层的情况,采用引孔打桩法沉桩但出现竖向裂缝,文中对该问题进行分析并采取相应的技术措施,同时也发现生产中存在的质量问题。     

某在建高层建筑桩基加固技术方案与应用

为了解决在建结构主体中因引孔静压成桩后引孔深度大于管桩桩底深度形成桩底脱空问题,在比选工程中常见桩基加固方法(注浆、锚杆静压钢管桩、微型灌注桩、微型钢管桩)的基础上,采用了微型钢管桩预应力封桩加固技术方案,同时对该加固方案进行了设计,并介绍了其施工工艺.最后,对加固后本工程的单桩进行竖向抗压静载试验和建筑变形监测.结果表明,加固桩极限承载力Qu≥1 300kN,满足钢管桩设计承载力650kN要求,监测的沉降变形比较稳定,趋于收敛.     

人工挖孔桩桩侧与桩端阻力的试验研究

人工挖孔桩是目前广泛采用的一种桩基础形式,具有造价低、工艺简单、质量控制容易、承载力较高等优点。人工挖孔桩端承桩为主,桩端持力层通常为强风化、中风化和微风化基岩。在计算桩的竖向承载力时,一般不考虑桩侧阻力的作用,桩侧阻力是否参与桩的竖向承载力计算影响到人工挖孔桩的经济性,有时甚至决定采用挖孔桩方案的可行性。本文介绍厦门某高层商住大楼人工挖孔桩的静载试验结果,分析了孔桩竖向承载力的试验值与设计计算值之间的差异,得出本地区强风化花岗岩土层的实际承载能力比规范法设计计算的设计值要大。     

浅论人工挖孔桩基础的检测与验收

从挖孔桩基底岩样取样数量的确定、桩身质量检验、桩身混凝土取样、单桩竖向承载力检测等方面探讨了人工挖孔桩基础的检测与验收,并通过工程实例进行了说明,归纳了挖孔桩基础验收应检查的资料,以确保人工挖孔桩的质量。     

人工挖孔桩后注浆效果分析与研究

通过人工挖孔桩后压浆技术在抚州市某商住楼工程中的应用,分析对比了灌注桩后注浆单桩竖向承载力的提高幅度以及承载力估算值与实测值的差别,揭示了钻孔灌注桩桩底后注浆在竖向荷载作用下的承载性状及桩侧、桩端阻力发挥特性,并提出了工程桩的设计、施工建议,以期指导实践。     

逆作法中人工挖孔桩顶钢柱快速定位施工技术

某综合楼项目处于商业中心区,采用逆作法,桩基础为人工挖孔桩,竖向承重构件为钢管混凝土柱。介绍了逆作法中人工挖孔桩顶钢柱快速定位施工技术。     

Experimental evaluation of cyclic behavior of batten columns

An experimental study was performed for batten columns subjected to combination of constant axial compression and reversed cyclic lateral loads to evaluate their cyclic response, available ductility and post failure behavior under seismic conditions. To determine and evaluate the available ductility of batten columns, the backbone curves have been developed using experimental hysteresis curves of columns. The effect of different parameters such as axial compression, distance between battens and distance between chords on the available ductility of batten columns have further been studied. The results reveal that the available ductility of batten columns is considerably low compared with solid web columns. The failure mode of batten columns is the combination of local and overall buckling of their bottom chords. The geometrical specifications of batten columns have no considerable and uniform effect on their available ductility. Moreover, it is shown that the backbone curves of batten columns are basically different from solid web columns.     

Seasonal variation and impact factors of available phosphorus in typical paddy soils of Taihu Lake region,China

Phosphorus loss from soil can play an important role in eutrophication of aquatic bodies. The seasonal variation of available phosphorus in soil profiles of three major paddy soils (Bai soil, Huangni soil and Wushan soil) during wheat and rice growth seasons was studied in the Taihu Lake region of China. The results were as follows: the available phosphorus contents differed in the three paddy soils. Available phosphorus content in Bai soil was the lowest in these soils. The available phosphorus content decreases rapidly with depth from the soil surface and reach the minimum value at approximately 45 cm before increasing slightly near the groundwater. The contents of available phosphorus were higher in February (tillering and shooting period of wheat) and in September (full heading time of rice) than in other months. The total phosphorus content strongly affects available phosphorus content in the studied soils. During the period of wheat cultivation, they show a typical power function relationship with correlation coefficient r = 0.6492** (n = 13), a significant positive linear correlation. In addition, available phosphorus content has a remarkable positive linear correlation with organic matter content, r = 0.9111** (n = 13), and a remarkable negative linear correlation with pH value, r = ?0.5945* (n = 13). In Wushan soil, there is a negative linear correlation between clay content and available phosphorus content, r = ?0.9289* (n = 4). Therefore, total phosphorus content, organic matter content and pH value are major impact factors on available phosphorus content in these soils.     

复合微生物菌剂对污泥堆肥营养学指标的影响

为了研究外源微生物对营养土堆制过程的影响,选择复合微生物菌剂(HBH-Ⅱ)开展了污泥堆制营养土的试验。结果表明:①复合微生物制剂的添加增加了总氮的损失,但大幅度提高了碱解氮、有效磷含量及发芽指数,而对总磷、钾含量的增加率贡献较小。②总氮与所有指标均呈负相关,其他指标之间都为正相关;在0.05的水平下,HBH-Ⅱ的添加量与总氮呈显著负相关、与有效磷及发芽指数呈显著正相关;在0.01的水平下,总氮与碱解氮、有效磷呈极显著负相关,而HBH-Ⅱ投量与碱解氮、碱解氮与有效磷呈极显著正相关。③菌剂中存在对氮、磷元素转化非常活跃的微生物种群,能够将非碱解氮成分转化为碱解氮、固态氮转化为气态氮,还能提高非有效磷转化为有效磷的效率。④HBH-Ⅱ对污泥堆制营养土过程中营养学指标及发芽指数的影响次序为碱解氮发芽指数(总氮=有效磷)钾总磷。     

滇中地区土壤有效磷含量对植物理化性质的影响

以滇中地区昆明、玉溪和曲靖3市所属12个县（市、区）的云南松、矮杨梅、牛尾蒿等32种主要森林植物为研究对象,共采集了32种346批次叶（茎）、17种43批次枝及对应植物根部土壤为实验样品,测定了其抽提物含量、灰分含量、热值和土壤有效磷含量,分析了土壤有效磷含量对植物理化性质的影响,进而研究了土壤有效磷含量对植物燃烧性的影响。结果表明：（1）土壤有效磷在一定程度上增加叶的抽提物含量和热值,降低叶灰分含量,但枝理化性质对土壤有效磷含量的响应不及叶明显;（2）滇青冈、华山松、黄茅、南烛、牛尾蒿、野八角、银荆、云南樟的叶理化性质对土壤有效磷含量响应较灵敏,云南油杉和云南樟的枝理化性质对土壤有效磷含量响应较灵敏,土壤有效磷也能相对明显地增加云南松、华山松、地盘松、牛尾蒿、紫茎泽兰等滇中地区常见植物枝、叶（茎）的抽提物含量和热值,降低他们的灰分含量;（3）在生境相似的条件下,土壤有效磷含量与抽提物含量、热值呈显著正相关关系。土壤有效磷能够在一定程度上增加植物的粗脂肪含量和热值,降低其灰分含量。这种变化趋势有利于植物燃烧性的提升。并就加强滇中地区森林火灾风险治理提出相应的措施与建议。     

Prediction of punching shear strength of two-way slabs

The punching shear strength of two way slabs without shear reinforcement and without unbalanced moment transfer is estimated using both neural networks and new simplified punching shear equations. An artificial neural network (ANN) was used to predict the punching shear strength of internal slab-column connections. Neural network analysis is conducted using 244 test data available in the literature and experiments conducted by the authors to evaluate the influence of concrete strength, reinforcement ratio and slab effective depth on punching shear strength. A wide range of slab thicknesses (up to 500 mm) and reinforcement ratios were used. In general, the results obtained from the neural network are very close to the experimental data available. The test results were used to develop two new simplified practical punching shear equations. The equations also showed a very good match with available experimental data. Four equations for the punching shear strength prescribed in well-known specifications were evaluated based on the available experimental results. This paper includes a discussion of the parameters of punching shear strength in the American, Canadian, British and European specifications.     

SCHEDULING WITH CO-EVOLVING RESOURCE AVAILABILITY PROFILES

Existing resource allocation models schedule activities by balancing resource requirement with resource availability using the resource available profile as a constraint to guide the scheduling process. The given resource available profile, however, may not be the best configuration for the project. Consequently, the resource available profile may have to be modified to produce improved resource utilization. With each modification the activities have to be rescheduled to meet resource availability constraints. A model is presented herein which is able to generate activity schedules that is optimal with respect to the resource available profile that is configured interactively with the schedule for minimum resource idling. The entire project is subdivided into separate resource contracts. The model then employs genetic algorithm (GA) to determine the start times of the activities and simultaneously self-adjust the resource hiring levels and end-dates for each contract in order to minimize the objective function. Results show that the model can provide schedules and corresponding resource available profiles that yield considerable savings in idle resources even in multi-resource problems.     

紫茎泽兰茎燃烧性与土壤有效磷含量的关系

以滇中地区的紫荆泽兰茎为研究对象，测定了紫茎泽兰茎的粗脂肪含量、灰分含量、热值以及紫荆泽兰根系土壤有效磷含量。以粗脂肪含量、灰分含量以及热值为评价指标，计算了紫茎泽兰茎的燃烧性综合指数，并分析了紫茎泽兰粗脂肪含量、灰分含量、热值以及燃烧性综合指数与土壤有效磷含量的关系。研究表明，紫茎泽兰茎的粗脂肪含量、热值以及燃烧性综合指数与土壤有效磷含量呈正相关关系的比例分别为65.22% 、52.17% 和56.52% ，灰分含量与土壤有效磷含量呈负相关的比例为60.87%。土壤有效磷含量可在一定程度上增加紫茎泽兰茎的粗脂肪含量、热值，降低其灰分含量，并增强其燃烧性。     

Easy proft maximization method for open-pit mining

A methodology applicable at any phase of a surface mining project for evaluating its current technical and economic feasibility is presented.It requires the typically available quantitative data on the ore-body,with its three-dimensional block model developed upon accurate interpolations.Thus it allows estimations of exploitable reserves in function of various cut-off grades,such as the average grade of mineable ore,the tonnages of ore and waste rock,stripping ratios and proft estimates for different production levels.If cost evaluations of essential mine operations are available(such as ore mining,waste removal,ore concentration,transportation,indirect project costs and expected concentrate selling prices),the methodology will provide clear indications on the economic feasibility of mining,including the best available options at any moment.Simple expressions are developed on the basis of a proft mathematical function and an application example is presented with data available from an existing iron ore deposit.     

Indoor Air Quality: Exploring Policy Options to Reduce Human Exposures

Deciding between the different policy approaches available for reducing human exposures to indoor pollutants is an exceptionally complex task. These options can range from waiting until more definitive information is available to enacting regulatory standards, with many variations in between. This paper presents some of the factors policy-makers must consider in establishing indoor air quality policies, and the role researchers should play in ensuring that indoor air policies are based on the best available scientific information.     

Required and available moment redistribution of continuous steel-concrete composite beams

Based on the ultimate limit state analysis, the required moment redistribution to enable full plastic mechanism for continuous composite beams is derived. The composite beams studied are continuous over the internal support and with a uniform section along the beams which are one of the conventional steel structural forms in Chinese construction practice for buildings and medium span bridges. It is illustrated that the required moment redistribution for the beam increases as the ratio of negative to positive moment resistance reduces, but decreases as the span difference, or the difference of load in the two spans increases. A method to assess the available moment redistribution based on the rotation capacity at the notional plastic hinges of a composite beam is developed. The potential moment redistribution in a continuous composite beam is also assessed when the available rotation capacity at the notional hinge fails to satisfy the required capacity capable of a plastic design. For a continuous composite beam to develop full plastic design, the available moment redistribution for the beam should be greater than or at least equal to the moment redistribution required, hence the full moment redistribution from the hogging region to the sagging region in the beam is capable. The derived available moment redistributions agree with the test results and computer simulations, but in a general lower bound of the strength capacity. An example is given and the results are compared with that based on the moment redistribution proposed in the present Chinese design code for steel-concrete composite beams. The present study provide a design approach to assess the load carrying capacity for a continuous composite beam based on the available moment redistribution capable depending on the rotation capacity or the force ratio etc rather than a fixed value of moment redistribution proposed, so that in most cases, an economic design is capable.