深层搅拌法在超软弱港口地基上的工程应用

某港口堆场地基上部5．0m系吹填而成，地表下18m范围均属软土，经真空预压初级加固后地基承载力仅在80—90kPa，局部区域上部淤泥土层土性指标较差，含水量大于50％，地基承载力不足60kPa。为了使地基达到230kPa的承载要求，设计采用深层搅拌法加固超软弱地基。通过现场成桩工艺试验和检测表明，桩身水泥土强度在90d龄期时大于1．80MPa，单桩承载力标准值大于150kN，以φ600桩径、桩长13．5m、置换率为0．308和φ500桩径、桩长13．5m、置换率为0．267两种方案布置的复合地基承载力标准值均超过了230kPa的设计要求。试验结果表明，深层搅拌法在港口超软弱地基土应用只要施工工艺适当，完全可以使地基承载力提高2—3．5倍以土，从而节省大量的工程投资。     

往复流中双向导向叶冲动透平模型性能试验研究

研制了 30 0双向自调导叶透平试验机组 ,安装在 10 0 0活塞式往复流透平试验台上 ,对两种叶轮方案和 6种不同喷咀、扩压器进行了不同活塞行程、不同周期和不同恒定输出电压下性能试验。试验结果表明在喷咀出口角α1=2 1 5°、扩压器入口角α2 =6 5 5°和α1=2 4°、α2 =6 3°组合最佳 ,最高效率达 5 3 3% ,而且在宽广流量系数范围内 ,特别是大流量系数范围内都有较高效率。大大优于常用对称翼透平。将上下游导叶固定 ,变成双向固定导叶透平。用No 1叶轮和 6种导叶出口角组合进行试验。表明最佳导叶出口角为 2 4°～ 30°,最高效率仍达 38 5 % ,比对称翼透平仍高许多     

GPS单频精密单点定位方法与实践

讨论了单频精密单点定位的解算方法与思路,编写了单频精密动态单点定位的程序,实现了事后动态单频精密单点定位.     

基于动态检测平台的GPS接收机动态性能检测研究

介绍了一种新型动态检测平台,设计了GPS动态差分试验和双动态差分试验,分析了GPS动态单点定位、动态差分测量、双动态差分测量在两种不同速度条件下进行了的试验数据.     

肋柱式锚杆支挡结构的徐变次内力分析

采用老化徐变理论和等效弹性模量法,对肋柱式锚杆支挡结构的徐变影响提出了具体计算方法,并通过实例计算了支挡结构的徐变次内力。计算结果表明,在逆作法条件下,随着开挖深度的加大,岩土侧向压力也增大,使后期施工的混凝土构件产生的徐变次内力也随之增大;考虑徐变后使结构设计更加安全可靠,尤其坡脚处后期浇筑的混凝土构件,更要关注徐变的影响。     

某基坑工程土钉支护工作性状试验研究

通过对广州天河荟雅苑基坑工程土钉支护进行试验和研究,分析了土钉支护体系的工作性状,并为同类工程的设计提供了一定的依据。     

U-Pb Age Determination for Seven Standard Zircons using Inductively Coupled Plasma–Mass Spectrometry Coupled with Frequency Quintupled Nd-YAG (λ = 213 nm) Laser Ablation System: Comparison with LA-ICP-MS Zircon Analyses with a NIST Glass Reference Material

This paper evaluates the analytical precision, accuracy and long‐term reliability of the U‐Pb age data obtained using inductively coupled plasma–mass spectrometry (ICP‐MS) with a frequency quintupled Nd‐YAG (λ = 213nm) laser ablation system. The U‐Pb age data for seven standard zircons of various ages, from 28 Ma to 2400 Ma (FCT, SL13, 91500, AS3, FC1, QGNG and PMA7) were obtained with an ablation pit size of 30 μm diameter. For ²⁰⁷Pb/²⁰⁶Pb ratio measurement, the mean isotopic ratio obtained on National Institute of Standards and Technology (NIST) SRM610 over 4 months was 0.9105 ± 0.0014 (n = 280, 95% confidence), which agrees well with the published value of 0.9096. The time‐profile of Pb/U ratios during single spot ablation showed no significant difference in shape from NIST SRM610 and 91500 zircon standards. These results encouraged the use of the glass standard as a calibration standard for the Pb/U ratio determination for zircons with shorter wavelength (λ = 213 nm) laser ablation. But ²⁰⁶Pb/²³⁸U and ²⁰⁷Pb/²³⁵U ages obtained by this method for seven zircon standards are systematically younger than the published U‐Pb ages obtained by both isotope dilution–thermal ionization mass spectrometry (ID‐TIMS) and sensitive high‐resolution ion‐microprobe (SHRIMP). Greater discrepancies (3–4% younger ages) were found for the ²⁰⁶Pb/²³⁸U ages for SL13, AS3 and 91500 zircons. The origin of the differences could be heterogeneity in Pb/U ratio on SRM610 between the different disks, but a matrix effect accuracy either in the ICP ion source or in the ablation‐transport processes of the sample aerosols cannot be neglected. When the ²⁰⁶Pb/²³⁸U (= 0.2302) newly defined in the present study is used, the measured ²⁰⁶Pb/²³⁸U and ²⁰⁷Pb/²³⁵U ages for the seven zircon standards are in good agreement with those from ID‐TIMS and SHRIMP within ±2%. This suggests that SRM610 glass standard is suitable for ICP‐MS with laser ablation sampling (LA‐ICP‐MS) zircon analysis, but it is necessary to determine the correction factor for ²⁰⁶Pb/²³⁸U by measuring several zircon standards in individual laboratories.     

倒Y形竖井联系测量

介绍在小直径竖井联系测量中取消联系三角形,改用单根钢丝定点,全站仪引测高程的施测方法。     

等截面单桩抗拔承载性状试验研究

在基坑中对等截面单桩进行了抗拔静载试验，在桩身设置应变式钢筋计，成功测得桩身各截面的应变数据。分析试验所得数据，对试验抗拔桩抗拔系数的取值、侧摩阻力的发挥、混凝土桩身的开裂等进行了探讨，相应给出了抗拔桩的设计建议。     

Effect of a submerged bay-mouth breakwater on tsunami behavior analyzed by 2D/3D hybrid model simulation

The hybrid numerical model had been developed to simulate a complicated 3D flow around structures generated by tsunami. In the model, the conventional 2D model is adopted for the wide region far from structures and the 3D non-hydrostatic pressure model is used in the limited region adjacent to structures. The applicability of the model is shown by comparisons of the numerical results with the experimental results of the laboratory model tests and the numerical analysis results of the conventional whole 2D simulation. In addition, the effect of a submerged structure at the opening of a breakwater is discussed from the numerical simulations by the hybrid model. The submerged structure improves the stability of the rubble mound and reduces the tsunami inflow into the bay, while it increases the water surface velocity around the opening of the breakwater. The increase of surface velocity causes the increases of impulsive forces by collision with drafts and so on.