扩建工程对原泵房结构安全性影响分析

介绍了扩建工程是否影响原泵房结构安全以及沉降缝处裂缝是否会继续扩展和检测方法,并得出安全性鉴定结论,并给出处理意见。     

Experimental study of the performance of geosynthetics-reinforced soil walls under differential settlements

The deformation performance and settlement failure mechanism of geosynthetics-reinforced soil (GRS) walls are the two key points of engineering design under the differential settlement. This paper presents model tests of deformation performance and failure mechanism of the GRS wall with and without lateral restriction under differential settlement conditions. The observation and measurement results, including force and vertical displacement of geosynthetics and lateral deformation of facing panels, indicate good settlement control performance of GRS wall during construction and under differential settlement. Results indicate that the influence of the stress state of facing panels on the settlement control performance of GRS wall cannot be ignored. And the differential settlement failure of GRS wall is likely to occur in the joint of facing panels and geosynthetics. For good illustrations, two analytical approaches about deformation and stress of geosynthetics were proposed based on elastic cable theory, in GRS wall with and without lateral restriction. The expressions exclude the necessity to carry out sophisticated numerical analyses to stress and deformation and may help to develop the design guidelines for such GRS wall.     

Scale effect on the behaviour of geogrid-reinforced soil under repeated loads

One of the most useful geosynthetics in soil reinforcement is geogrid due to its high tensile strength, having a great influence on soil skeleton reinforcement and eventually, increasing bearing capacity of the foundation. In this research, a series of 36 repeated plate load tests have been carried out to investigate the scale effect on geogrid-reinforced soil, tending to further understanding of the behaviour of geogrid-reinforced soil system. Four different soil grains sizes, two different geogrid's aperture sizes (with roughly the same tensile strength) and three different loading plate sizes are the variables considered. During the tests, the applied loading and soil surface settlements were recorded to evaluate the systems' response. As it was expected, the reinforced soil exhibited higher bearing capacity than the unreinforced status, up to 635%. The results show that increasing loading plate size and soils' particle size fortify the response of foundation, especially in reinforced status, against the loading plate penetration. The results further focused on the important role of scale effect on the response of reinforced foundation. It was understood that the optimum nominal aperture size of geogrids should be about 4 times of medium grain size of soil. Also, it was found out that in order to acquisition of highest reinforcement benefits, the footing's width should be in the range 13–25 (20 in average) times of medium grain size of the backfill. Finally, to achieve the best results, it is recommended that the aperture size of geogrids should be selected roughly 0.2 times of footing width.     

某地区盾构施工引起的土层沉降变形分析

为研究盾构施工引起的地面沉降,选取宁波地区有代表性的典型土层,运用经验公式与数值模拟相结合的方法,定性分析了盾构施工扰动引起的各土层沉降曲线形态。提出了初始敏感因子和深度敏感因子的概念,推导得出了各典型土层的敏感因子的初步建议值,详细阐述了地面沉降与盾构埋深的线形相关性。为盾构近距离穿越重大管线或建、构筑物等风险点时穿越土层的选择提供了理论参考,对地铁线路平、纵断面确定具有指导意义。     

建筑工程造价预结算审核工作要点研究

为了合理确定工程造价,避免预结算阶段出现高估冒算的情况,从介绍建筑工程造价预结算审核工作内容和方法入手,对其审核工作要点进行了探讨,以期实现对工程造价计价活动的有效监管,保障施工方和建设方的合法权益。     

谈工程造价的结算审核

分析了工程结算编制存在的问题,对工程结算审核的内容——工程量编制审核、套用定额的审核、费用的审核等进行了阐述,并给出了工程造价的审核方法,以达到提高经济效益的目的。     

Study of the behavior of mechanically stabilized earth (MSE) walls subjected to differential settlements

The limit equilibrium (LE) analysis has been used to design MSE walls. Presumably, the deflection of MSE walls can be limited to an acceptable range by ensuring sufficient factors of safety (FOSs) for both external and internal stabilities. However, unexpected ground movements, such as movements induced by excavations, volume changes of expansive soils, collapse of sinkholes, and consolidations of underlying soils, can induce excessive differential settlements that may influence both the stability and the serviceability of MSE walls. In this study, a numerical model, which was calibrated by triaxial tests and further by a specially-designed MSE wall tests, investigated the behavior of an MSE wall as well as the influence of various factors on the performance of the MSE wall when the wall facing settled relatively to the reinforced zone. The numerical results showed that the differential settlement would cause substantial vertical and horizontal movements for the MSE wall, as well as an increase in lateral earth pressure and geosynthetic reinforcement strain. The maximum horizontal movement and increase of the lateral earth pressure occurred at about 1.0 m above the toe. The differential settlement resulted in a critical plane that coincided with the plane of 45°+?/2. The maximum increase of the strain for each geogrid layer occurred in that plane, and the bottom layer had the greatest strain increase among all layers of reinforcement. The study further indicated that the surcharge, backfill friction angle, tensile stiffness of geogrid, reinforcement length and MSE wall height had noticeable influences on horizontal and vertical movements, and strain in geosynthetics. According to the results, the MSE wall that had a higher factor of safety would have less movements and geosynthetic strain increase. In contrast, only the friction angle, tensile stiffness and MSE wall height showed some degree of influence on the lateral earth pressure due to differential settlements.     

谈建筑物沉降观测的方法和注意事项

阐述了沉降监测在点位布设、施工方法、数据整理过程中用到的典型方法,并对后期数据沉降量的计算所用时点差法和分析数据用的回归模型做了简单的阐述,以期指导实践。     

考虑孔隙贯通率的弹性地面基坑降水沉降研究

从孔隙贯通率的角度出发,分析了工程中普遍采用的基于弹性理论的地面沉降计算方法存在的问题,考虑粘土层和砂土层工程性质的差异,引入修正系数x对计算公式进行修正,并以苏州工业园区天地源橄榄湾地下车库A区基坑沉降为例,利用这两种方法进行了计算并对其结果做出对比分析,修正系数法的计算结果更接近实测值,而主要沉降发生在粘性土层中,砂土层沉降量较小,而卵石层认为不沉降.     

石武客专驿城梁场双层存梁沉降观测技术

为了确保双层存梁的安全,对双层存梁的存梁台座进行了沉降观测,具体阐述了沉降观测的准备工作和施测步骤,以便技术人员针对现场情况作出正确调整,避免造成经济损失。