拟建海堤的选型及其对邻近桥墩的影响

基于深圳市大铲湾(宝安中心区段)海堤(西侧)工程与深圳市沿江高速公路桥桩工程,通过对抛石海堤排水固结处理软基、大袋砂海堤排水固结处理软基、抛石海堤爆破处理软基、抛石海堤挖淤处理软基等4种不同类型海堤的基本结构型式及其技术特点进行对比,确定了拟建海堤(西侧)的结构型式;并基于FLAC软件数值模拟拟建海堤(西侧)施工刚完成时对沿江高速公路桥墩的影响.结果表明:拟建海堤(西侧)采用重力式斜坡堤,并使用大袋砂海堤排水固结处理软基方案比较合理;拟建海堤(西侧)施工刚完成时,离海堤边线40.8 m处的桥桩水平向最大位移约为7.5mm,离海堤边线176.8m处的桥桩水平向位移更小,显然拟建海堤(西侧)施工时对已建桥桩的影响甚微.     

Effects of hillslope geometry on spatial infiltration using the TOPMODEL and SCS-CN models

ABSTRACT

The estimation of infiltration is a main issue in runoff simulation. The geometry of hillslopes (plan shape and profile curvature) may affect the responses, as well as infiltration over the hillslopes. In this study, the equations of TOPMODEL (a topography-based model) were applied to complex hillslopes to develop the complex TOPMODEL. This model was coupled with the SCS-CN (Soil Conservation Service Curve Number) model to examine the effects of geometry on infiltration and derive a saturation excess-based curve number (CN). The effects of plan shape and profile curvature upon the spatial distribution of CN and infiltration were studied. The results show that convergent hillslopes have 15.4% less infiltration and divergent hillslopes have 7.8% more infiltration than parallel ones. The infiltration over concave hillslopes is 13.5% lower and infiltration over convex hillslopes 5.8% higher than for straight ones. The degree of convergence/divergence has a greater effect on the CN compared to that of profile curvature.     

山西代县地震台前兆数字化形变观测资料异常特征研究

结合2010年至2011年国外发生的M〉6．0、山西地区4．0级以上地震,对山西代县地震台数字化形变观测资料进行系统研究,分析其映震情况和映震特征。研究发现,在多次中强以上地震前几小时至几天左右,各测项均记录到固体潮畸变、高频脉冲、抖动、转折等异常形态。     

山西河津4．8级地震临汾地震台数字形变资料异常特征及同震响应分析

文章对山西河津4．8级地震前后临汾地震台各形变资料异常变化特征及同震响应的差异性进行分析,结果表明,震前各仪器观测资料均存在明显的异常,由于仪器频率响应范围的差异性,各仪器对同一地震的响应也存在显著不同。     

SMA阻尼器偏心结构平-扭震动控制试验研究

为了验证提出的新型筒式自复位形状记忆合金阻尼器(telescopic recentering shape memory al-loy damper,TRSMAD)对结构平动-扭转耦联振动反应的抑制作用,进行了偏心结构消能减震体系的振动台试验。设计了一个1/4缩尺的三层两跨单向偏心的钢框架模型,将提出的新型SMA阻尼器安装在结构底层的一侧,通过振动台分别对无控条件下和装有阻尼器的有控条件下的结构反应进行了研究。试验结果表明:(1)在各地震波作用下,TRSMAD对结构的平动反应有很好控制效果,而对结构各层扭转角位移的控制效果稍低;(2)不同地震波下的控制效果有所不同:对结构的平动位移而言,天津波的减震率最高,El Centro波次之,最后为Taft波;对结构扭转角的控制,平均而言,除了天津波作用下第二层为特例外,对El Centro波的减震效果最好,其次为Taft波,最后为天津波;(3)同一地震波下,阻尼器对结构模型一层的位移控制效果较其他层为优。     

Application of an SMA-based hybrid control device to 20-story nonlinear benchmark building

This paper investigates the seismic response control of a 20-story nonlinear benchmark building with a new recentering variable friction device (RVFD). The RVFD combines energy dissipation capabilities of a variable friction damper (VFD) with the recentering ability of shape memory alloy (SMA) wires. The VFD that is the first subcomponent of the hybrid device consists of a friction generation unit and piezoelectric actuators. The clamping force of the VFD can be adjusted according to the current level of ground motion by adjusting the voltage level of piezoelectric actuators. SMA wires that exhibit a unique hysteretic behavior and full shape recovery after experiencing large strains is the second subcomponent of the hybrid device. Numerical simulations of a seismically excited 20-story benchmark building are conducted to evaluate the performance of the hybrid device. A continuous hysteretic model is used to capture frictional behavior of the VFD and a neuro-fuzzy model is employed to describe highly nonlinear behavior of the SMA components of the hybrid device. A fuzzy logic controller is developed to adjust the voltage level of VFDs for favorable performance in an RVFD hybrid application. Results show that the RVFD modulated with a fuzzy logic control strategy can effectively reduce interstory drifts and permanent deformations without increasing acceleration response of the benchmark building for most cases. Copyright © 2012 John Wiley & Sons, Ltd.     

A revised approach to discriminating sediment transport histories in glacigenic sediments in a temperate alpine environment: a case study from Fox Glacier,New Zealand

Clast shape measurements have developed into a standard method for reconstructing the transport histories of sediments in glacial environments. The majority of studies use the ‘RA‐C₄₀’ covariance approach, with some researchers routinely including clasts of varying lithologies within their samples. The corollary is that variable lithological properties may control clast form and roundness, rather than debris‐transport mechanisms. Despite this, the role of lithology on clast shape in glacial environments has rarely been analysed. Furthermore, some studies have reported difficulties in using the RA‐C₄₀ co‐variance plot in discriminating clasts that have undergone subglacial transport, and clasts that have been modified by fluvial activity. Results from a glacierized valley in a temperate alpine setting indicate that detailed analysis of clast shape where samples are of uniform lithology, although time consuming, is a useful tool in the investigation of deposits in glaciated environments. Copyright © 2012 John Wiley & Sons, Ltd.     

浙江近海曼氏无针乌贼(Sepiella maindroni) 繁殖生物学特性变化研究

采用常规生物学方法和统计回归分析方法,对浙江近海曼氏无针乌贼的繁殖生物学特性进行了研究,比较了不同时期浙江近海曼氏无针乌贼卵巢成熟系数(GSI)、生物学体型及个体生殖力与生物学指标关系。结果表明,浙江近海曼氏无针乌贼GSI在4月份达到最高(9.51%±7.23%),相比20世纪60年代初、80年代初,自然海域曼氏无针乌贼的性腺发育提前,且生殖期延长。20世纪80年代初曼氏无针乌贼的生物学体型、怀卵量及个体生殖力均大于60年代初和自然海域曼氏无针乌贼,同时曼氏无针乌贼在人工养殖条件下生物学体型、怀卵量及个体生殖力增大。浙江近海曼氏无针乌贼的个体生殖力均随着胴长(ML)、体质量(W)、卵巢质量(WO)、GSI这些指标的增大而增大,除体质量相对生殖力(FW)与ML为密切正相关外,个体生殖力与这些指标的关系均达到了极显著水平(P<0.01)。多元线性逐步回归分析表明,WO是影响浙江近海曼氏无针乌贼个体生殖力的最重要指标。     

Application of the parabolic bay shape equation to sand and gravel beaches on Mediterranean coasts

The equation most commonly used to describe the bay planform was proposed by Hsu and Evans (1989) and it was obtained through empirical analysis of sand beach planforms.In the last decade interest in gravel sediments increased owing to their greater stability on beaches, compared with sand sediments. Due to the differences between the morphodynamics of sand and gravel beaches, which is strictly influenced by their different hydraulic characteristics, it was necessary to create a predictive instrument for this beach type as well.Therefore, in this study the standard Hsu and Evans equation (1989) was modified in order to make it applicable not only to sand beaches but also to gravel beaches. The shoreline was computed according to a parabolic model in polar coordinates whose coefficients are considered linearly dependent on the wave direction and related to the beach type. The estimation of the free parameters of the model was performed according to a statistical analysis of a shorelines data set of Mediterranean sand and gravel embayed beaches.