双速度法检测基桩完整性试验研究

基桩低应变测试法被广泛应用于测试桥梁基桩、打入桩和抗滑桩等的完整性。但是,桩顶非自由的情况测试就非常困难。此时可采用双速度法检测,此方法也适于测试已有建筑物下的基桩及基桩与上部结构相连且桩长未知的情况。通过16根有承台和无承台模型桩的单速度和双速度测试,取得766组数据进行分析,得出此方法完全可以应用于工程基桩检测中,对基桩完整性检测具有现实意义。     

几种初至自动拾取算法在地震波法隧道超前探测中的对比分析

在地震勘探中,尤其在浅层地震勘探、层析成像和地震波法超前探测中初至时间拾取精度直接影响勘探区域地质结构的反演结果，初至时间的自动拾取也是隧道超前地质预报地震数据处理的一个关键环节。介绍4种初至自动拾取算法--最大振幅法、能量比法、STA/LTA（长短时窗比）法和AIC（峰度赤池信息量准则）法，利用云南某隧道超前地质预报采集到的1组地震数据，对4种初至自动拾取算法进行对比分析，结果显示SLA/LTA算法拾取的初至时间更为精确，AIC法、能量比法次之。进一步利用其他隧道超前地质预报采集到的几组数据进行对比分析，获得相同结论。     

斜坡式海堤挡浪墙波浪力对比分析

以东部沿海某海堤工程为例，分别通过物理模型试验方法和数值模型方法模拟海堤挡浪墙受到的波压力大小及其分布情况，并进行对比分析。结果发现两者结论较为一致，说明数值模型方法在计算海堤挡浪墙波浪力方面具有较高的精度，可为类似工程提供借鉴。     

磁电弹固体中弹性波传播问题的研究进展

简要介绍了磁电弹材料的特征和基本方程，评述了这类材料中弹性波传播问题的研究进展，主要包括表面波、界面波和导波等。     

A kinematic wave approach to traffic statics and dynamics in a double-ring network

Recently there has been much interest in understanding macroscopic fundamental diagrams of stationary road networks. However, there lacks a systematic method to define and solve stationary states in a road network with complex junctions. In this study we propose a kinematic wave approach to defining, analyzing, and simulating static and dynamic traffic characteristics in a network of two ring roads connected by a 2 × 2 junction, which can be either an uninterrupted interchange or a signalized intersection. This study is enabled by recently developed macroscopic junction models of general junctions. With a junction model based on fair merging and first-in-first-out diverging rules, we first define and solve stationary states and then derive the macroscopic fundamental diagram (MFD) of a stationary uninterrupted network. We conclude that the flow-density relationship of the uninterrupted double-ring network is not unique for high average network densities (i.e., when one ring becomes congested) and unveil the existence of infinitely many stationary states that can arise with a zero-speed shockwave. From simulation results with a corresponding Cell Transmission Model, we verify that all stationary states in the MFD are stable and can be reached, but show that randomness in the retaining ratio of each ring drives the network to more symmetric traffic patterns and higher flow-rates. Furthermore we model a signalized intersection as two alternate diverge junctions and demonstrate that the signalized double-ring network can reach asymptotically periodic traffic patterns, which are therefore defined as “stationary” states in signalized networks. With simulations we show that the flow-density relation is well defined in such “stationary” states, and asymptotic traffic patterns can be impacted by signal cycle lengths and retaining ratios. But compared with uninterrupted interchanges, signalized intersections lead to more asymmetric traffic patterns, lower flow-rates, and even gridlocks when the average density is higher than half of the jam density. The results are consistent between this study and existing studies, but the network kinematic wave model, with appropriate junction models, is mathematically tractable and physically meaningful. It has offered a more complete picture regarding the number and type of stationary states, their stability, and MFD in freeway and signalized networks.     

消减波浪荷载的桥梁沉箱基础外形设计研究

基于波浪场中动水压强的空间分布特征,提出了消减跨海桥梁沉箱基础波浪荷载的方法:一是优化基础横截面外形,调节基础横截面外轮廓不同位置波浪压力的相位差,减小基础所受到波浪力和力矩;二是优化基础竖截面外形,减小水面附近波浪能量集中区域的截面尺寸,增大靠近海床面区域的截面尺寸,将基础下部的迎浪面设置为外伸斜面,利用斜面上波浪压力竖向分力产生的力矩抵消部分水平分力产生的力矩,从而消减桥梁基础上的总波浪力矩。对于大尺度矩形和圆端矩形截面的桥梁深水沉箱基础,基于势流绕射理论和边界积分方法进行分析,结果表明,相比于矩形截面,采用圆端矩形截面可有效减小基础的波浪力和力矩;相比于上下等截面的基础,采用下部迎浪面设置外伸斜面的基础可以大幅减小基础的波浪力矩。研究成果可为跨海桥梁深水基础设计提供参考。     

交通流中的回波及其传播特征

应用流体力学原理，针对交通流运动方程式，证明了交通流的回波及其传播特征，同时指出了在交通流理论界有较大影响的莱特希尔和惠特汉推导出的车流传播公式的理论误区。     

地震散射技术在盾构隧道海底孤石探测中的应用———以横琴隧道为例

针对珠海横琴海底盾构隧道孤石探测这一工程勘察难点,选用具有高分辨特点的地震散射新技术,通过小排列密集采集方式,进行2 m×1 m 的网格观测,获得轴向间距1 m、横向2 m、垂向0. 5 m 的三维速度结构和地质界面分布。以波速大于2 400 m/ s 为识别基岩与孤石的指标,得到其高程分布;对三维波速结构进行水平、纵向和横向切片,展现基岩与孤石的分布图像。勘探发现 26 处孤石,其中9 处直径超过3 m。通过证实,物探与钻探的吻合率达到90%,平均深度误差在1 m 以内。实际应用结果表明地震散射技术具有采集灵活、分辨率高的特点,特别适合孤石勘探。     

汽车电磁干扰故障的诊断与排除

干扰电磁波主要通过两种方式传播：一为“辐射干扰”,它主要干扰无线慢接收装置;二为“传导干扰”,它具有更大的危害性。阐述了电磁干扰机理及产生干扰电磁波的原因。介绍了防止电磁干扰的措施、电磁干扰故障的判断与排除。