钢管式土钉支护在深基坑支护中的应用

文章通过对桂林市某商住楼深基坑施工钢管式土钉支护成功经验，对采用土钉墙支护结构在深基坑的设计与施工作了介绍，供参考。     

土钉支护技术在房建工程深基坑中的应用

土钉支护是近几年新兴的挡土支护技术，尤其在高层建筑深基坑支护应用中取得了良好的经济效益和社会效益。本文就对土钉支护技术的优点进行简单总结，并探讨了土钉支护技术在房建工程中的应用。     

土钉墙支护技术在深基坑工程中的应用

土钉墙支护工期短,造价低,施工操作方便等优点,在深基坑支护工程中得到广泛应用,结合深基坑支护实例,介绍了深基坑土钉墙支护支护方案、施工工艺、边坡变形监测及其施工应急措施。     

复合土钉支护技术在深基坑支护工程中的应用

复合土钉支护技术是将土钉墙与其他支护形式或施工措施联合应用于土体开挖和边坡稳定的一种新的挡土技术。它将土钉墙与预应力锚杆等结合起来,使得土钉墙技术在深基坑中应用及垂直土钉墙成为现实,并改善了土钉墙支护形式变形较大的缺陷。本文主要介绍复合土钉支护技术在某科技大厦深基坑工程中的应用并结合工作实践中遇到的有关问题进行论述。     

土钉墙支护结构土钉最优间距初探

近年来,随着高层建筑的不断涌现,深基坑支护的技术和方法越来越受到重视。土钉墙支护就是常用的一种支护方法,但以往的土钉支护只是粗略地计算土钉长度和土钉间距,没有考虑不同深度基坑和土钉间距之间的影响。针对这一现象,本文探索不同深度基坑中最优间距的选择。     

土钉墙支护结构技术分析与应用

土钉墙支护由土钉、钢筋网喷射混凝土面板和加固后的原位土体三部分组成。土钉墙支护结构具有技术可靠、施工操作方便、造价相对较低等优点。广泛应用于深基坑支护工程中。本文结合工程实际,介绍土钉墙支护技术要点及应用效果。     

复合土钉支护技术在淤泥层的深基坑工程中的应用

在深基坑工程中,淤泥层是一种常见的土层,属于不良地质,如果处理不当,会对深基坑工程质量造成不良影响。复合土钉支护技术在深基坑工程中应用较为广泛,但在淤泥层使用中,会受到一定限制。本文就对淤泥层深基坑工程中复合土钉支护技术的应用展开探讨,以为淤泥层深基坑工程支护水平的提高提供有效参考。     

浅谈土钉墙支护技术在基坑工程中的应用

土钉墙支护,是用于土体开挖和深基坑旅工时保证边坡稳定的一种新技术。本文介绍了土钉墙的特点和适用范围、构造、土钉墙施工的一般原则和要求,并具体讨论了土钉墙支护方案中的施工工艺与施工的质量控制。     

关于土钉墙在深基坑支护中的应用研究

土钉墙是借助了土钉、土层与混凝土面层的共同作用形成的复合土体,目前深基坑支护在城市高层建筑中的应用逐渐普遍,而其影响的安全性、经济性也日渐突出,土钉墙则很好的提供了安全可靠的特性,并具有成本较低、结构轻便的优点。本文主要简述了土钉墙的基本概念,分析其应用特点及使用范围,并详细阐述了土钉墙在深基坑支护工程中的实际应用方式。     

试论深基坑工程中的复合土钉墙支护施工技术

近年来,在基坑支护工程中,由于复合土钉墙支护具有技术性可靠、施工工艺简单、施工工期短和成本低等优点,在深基坑支护工程中被广泛应用。本文作者结合某大型商场基坑工程实例,主要就复合土钉墙支护施工技术进行了阐述。     

实验室质量体系运行中的技术难点及解决方法 第一讲 实验室检测/校准结果符合性的判定

在实验室质量体系运行中,技术方面存在着许多难点问题,诸如在质量监控中检测或校准结果及与规范的符合性、方法的确认、测量不确定度评定、设备和标准物质的期间核查、人员比对、方法比对、实验室间比对结果的正确判断等。对于测量不确定度的评定、设备和标准物质的期间核查、能力验证和稳健统计等问题已进行过介绍。此次专门针对检测或校准结果及与规范的符合性判定、方法确认、质量监控中离群值的判定、结果可接受性的检查、最终测试结果的确定、人员和方法比对,实验室间比对的正确判定等技术难点的解决方法进行了详细的介绍。     

Comparative study of two phase-field models for grain growth

There exist different phase-field models for the simulation of grain growth in polycrystalline structures. In this paper, the model formulation, application and simulation results are compared for two of these approaches. First, we derive relations between the parameters in both models that represent the same set of grain boundary energies and mobilities. Then, simulation results obtained with both models, using equivalent model parameters, are compared for grain structures in 2D and 3D. The evolution of the individual grains, grain boundaries and triple junction angles is followed in detail. Moreover, the simulation results obtained with both approaches are compared using analytical theories and previous simulation results as benchmarks. We find that both models give essentially the same results, except for differences in the structure near small shrinking grains which are most often locally and temporary for large grain structures.     

金属材料拉伸试验测试结果不确定度的评定

GB／T228．1—2010标准中修改了评定拉伸试验测量不确定度的方法。通过测定卷板的拉伸性能,对规定总延伸强度和抗拉强度的性能指标进行了测量不确定度评定,分析了不确定度来源,剔除测量结果中的离群值,提供了一种拉伸试验测量结果不确定度评定的可行方法,并对评定过程中的几个问题进行了探讨。     

Prediction of thermal post buckling and deduction of large amplitude vibration behavior of spring–hinged beams

A general energy formulation to predict the thermal post buckling behavior of uniform isotropic beams is presented in this paper. The hinged ends of the beam contain elastic rotational restraints to represent the actual practical support situation. The large amplitude vibration behavior of beams is deduced from the post buckling results. The classical hinged and clamped conditions can be obtained as the limiting cases of the rotational spring stiffness. The numerical results, in the form of the ratios of the post buckling to buckling loads for various maximum deflection ratios, are presented in the digital form. An alternate independent formulation, based on the nonlinear finite element formulation, is also used in this paper to validate the numerical results of the present work. Further, the results for the large amplitude vibrations, deduced from the thermal post buckling results are also presented and these results compare very well with the finite element results, available in the literature, for the large amplitude vibration problem. These comparisons show an excellent agreement not only for the present work on the proposed thermal post buckling formulation but also on the deduced results for the large amplitude vibration of beams with the ends elastically restrained against rotation (spring–hinged beams). The numerical results presented confirm the efficacy of the proposed methodology used for predicting the post buckling behavior and deducing the large amplitude vibration behavior of the spring–hinged beams.     

Do laboratory frontal crash test programs predict driver fatality risk? Evidence from within vehicle line variation in test ratings

A number of studies have examined whether the National Highway Traffic Safety Administration's (NHTSA) frontal crash test results reliably indicate the risk of fatality or injury in serious crashes. The conclusions of these studies are mixed. Generally, studies that examine crashes in the circumstances as close as possible to those of the laboratory test find that crash test results do predict real-world risk, but studies of crashes outside those specific circumstances find either no support for the predictive validity of crash test results or limited support with important inconsistencies. We provide a new test of the predictive validity of the crash test results using information from multiple crash tests within vehicle lines, thus controlling for systematic differences in driver behavior across vehicle lines. Among drivers of passenger cars, we find large, statistically significant differences in fatality risk for vehicles with one- to four-star NHTSA ratings versus a five-star rating. We also examine the Insurance Institute for Highway Safety's frontal offset crash test, though our sample of vehicle lines tested twice or more is considerably smaller than for NHTSA ratings. Our results also support the predictive validity of the frontal offset crash test results for passenger cars, but not for trucks.     

Binding energy of liquid4He calculated by the hypernetted-chain method

The hypernetted-chain (HNC) method for quantum many-body calculations is investigated in some detail by means of calculations of the binding energy and the equilibrium density for liquid⁴He. The calculations are done for six different two-body potentials, and the results are compared with experimental results and other theoretical results obtained by the lowest order constrained variation (LOCV) method. Our HNC results are, in general, quite different from the results obtained by the LOCV method—the LOCV binding energies are generally reduced by 2–5 K in the HNC calculations. The results are also very dependent on the chosen potential, especially at high densities.     

A Numerical Study of the Thermal Characteristics of an Air Cavity Formed by Window Sashes in a Double Window

Given that the Korean government is implementing what has been termed the energy standards and labelling program for windows, window companies will be required to assign window ratings based on the experimental results of their product. Because this has added to the cost and time required for laboratory tests by window companies, the simulation system for the thermal performance of windows has been prepared to compensate for time and cost burdens. In Korea, a simulator is usually used to calculate the thermal performance of a window through WINDOW/THERM, complying with ISO 15099. For a single window, the simulation results are similar to experimental results. A double window is also calculated using the same method, but the calculation results for this type of window are unreliable. ISO 15099 should not recommend the calculation of the thermal properties of an air cavity between window sashes in a double window. This causes a difference between simulation and experimental results pertaining to the thermal performance of a double window. In this paper, the thermal properties of air cavities between window sashes in a double window are analyzed through computational fluid dynamics (CFD) simulations with the results compared to calculation results certified by ISO 15099. The surface temperature of the air cavity analyzed by CFD is compared to the experimental temperatures. These results show that an appropriate calculation method for an air cavity between window sashes in a double window should be established for reliable thermal performance results for a double window.     

金属材料试样制备与力学性能试验结果的相关性 第一讲 试样的取样部位及机加工与力学性能试验结果的相关性

介绍了金属材料试样制备与力学性能试验结果的相关性。对国家标准中关于力学性能试验试样取样和机加工的要求、力学试验取样和制样过程中需要注意的问题、机加工质量的检验等问题进行了讨论。结果表明金属材料试验试样的制备与力学性能试验的结果有着非常密切的相关性,由于这个原因,力学试验试样的取样和机加工必须严格按照国家标准的要求进行,机加工后必须检验加工质量,以保证力学试验结果的正确性。     

基于塑性破坏的承压水基坑突涌计算模型研究

针对软土地区不透水隔水层承压水基坑,从坑底土产生塑性变形破坏的力学机理出发,建立了基于塑性破坏的承压水基坑突涌计算模型,提出了屈服应力比概念和基坑突涌判断标准。用考证实例将模型计算结果与离心试验结果、现场观察结果以及压力平衡理论计算结果进行了比较。结果表明:模型计算结果与离心模型试验结果和现场观察结果比较吻合;而压力平衡理论判断结果与离心模型试验结果和现场观察结果有较大出入。因此,对于软土地区坑底存在不透水隔水层的承压水基坑,采用突涌塑性破坏模型分析基坑抗突涌稳定性是合理可靠的。     

Surface waves in fiber-reinforced anisotropic general viscoelastic media of higher orders with voids,rotation, and electromagnetic field

In this article, we investigated an effect of external magnetic field on the propagation of surface waves in a perfect electrically conducting fiber-reinforced anisotropic general viscoelastic media of rational and higher orders with voids in a rotating medium. The general surface wave speed is derived to investigate effect of electromagnetic field and rotation on surface waves in the presence of voids and viscosity. Boundary conditions are applied to obtain the secular equation for generalized types of waves. Particular cases of Stoneley, Love and Rayleigh waves are derived. The results obtained are more general in the sense that some earlier published results are obtained from our result as special cases. In the absence of voids, the results for viscoelasticity of order zero are in good agreement with the fiber-reinforced materials. Also by neglecting the reinforced elastic parameters, the results reduce to a well-known isotropic medium. It is observed that surface waves cannot propagate in a strong initially applied electromagnetic field and rotation. Numerical results for particular cases have been obtained and displayed graphically. The results indicate that the effects of voids, anisotropic, fiber-reinforcement, rotation and electromagnetic field are very pronounced and applicable for the phenomena.