厦门集美海相淤泥土质水泥土设计参数研究

水泥掺入量是水泥土设计的重要参数,直接关系到受加固地基的整体强度和工程成本。文章针对厦门集美临海区域淤泥土特性,通过室内配比试验和力学特性分析,考虑了3种常用水泥,研究水泥掺入量对水泥土强度的影响,并提出了水泥土抗压强度与掺入比的关系式,可为类似土质的水泥土设计提供参照。     

桩底注浆技术在公路工程中的应用研究

介绍了桩底注浆技术的方法原理、施工工艺、技术指标及承载力的确定方法,并通过实例讨论了该方法在公路工程中的应用前景及应用价值。     

含砂低液限粉土的路基填筑技术综述——粉土的物理力学性能与压实机理

粉土的工程性质较差,是比较差的路基填料。针对目前粉土路基填筑技术的研究仅局限在施工技术方面的这一不足,从粉土的物理力学特性出发,概述粉土的工程特性、压实标准以及压实机理．对于摸索和提高粉性土路基压实的施工工艺具有十分重要的作用。     

Estimation of TKE dissipation rates in dense bottom plumes using a Pulse Coherent Acoustic Doppler Profiler (PC-ADP) — Structure function approach

During a hydrographic survey in January 2006 the spreading of inflowing saline water was observed in the Arkona Basin (Western Baltic Sea). Two bottom mounted ‘pulse coherent’ acoustic Doppler profilers (PC-ADP) were used to measure the near-bottom current field of the dense plume with a high temporal (1 s) and spatial resolution (5 cm). In order to estimate the dissipation rate of turbulent kinetic energy () a structure function approach was applied to the beam velocity data. Simultaneous measurements with a microstructure shear profiler (MSS) and an acoustic Doppler velocimeter (ADV) supplied independent data for the verification of the structure function method. Additional measurements with standard CTD, near-bottom towed and vessel mounted acoustic Doppler current profilers (ADCP) completed the data set.The estimated dissipation rates from the structure function approach fit well with the values derived from the ADV and the MSS probe. It is shown that the structure function approach is a reliable and easily applicable method to derive estimates of TKE dissipation rates from PC-ADP beam velocities. The observed dissipation rates ranged between 5 · 10^− 6 and 1 · 10^− 8 W kg^− 1 depending on the hydrographic conditions. Inside the plume the dissipation rates exceeded that of the overlaying brackish water by two orders of magnitude. Since the noise level of velocity data in pulse coherent mode is considerably lower than in the Doppler mode the PC-ADP can also be used for estimates in marine environments with low turbulence level. Reynolds stresses estimated from the PC-ADP and the ADV agreed well at the same depth level. TKE production derived from PC-ADP measurements compared reasonably well with the dissipation rate of TKE in a varying environment.     

基坑宽度效应对坑底隆起的影响研究

该文通过不同宽深比基坑坑底隆起的数值模拟,分析了基坑宽度效应对坑底隆起的影响.研究揭示了不同宽深比基坑坑底隆起变形的规律,表明随着基坑宽深比的不断增加,坑底最大降起量不断增大.结合上海东西通道上跨地铁二号线的工程实例分析,指出对环境保护要求极高的宽大基坑,可通过将大基坑划分为小基坑的方式有效地控制坑底隆起.     

劈裂注浆在北京地铁4号线工程中的应用

结合北京地铁4号线成府路车站联络通道工程特点,为了提高土体整体稳定性和承载力,保证地铁结构安全,分析了粉土地层的性状,采用水泥-水玻璃双液浆,并据土质情况确定浆液配比与注浆压力,对土体进行劈裂注浆加固,取得了良好效果。     

冲击荷载作用下饱和粉土变形和强度试验

围海造地是解决土地紧张的有效途径,其中对软弱吹填土地基进行有效加固处理是围海造地的关键．结合强夯法加固饱和粉土地基的工程实例,通过MTS动三轴试验研究强夯冲击荷载作用对饱和粉土的变形和强度特性的影响．通过动三轴试验采用不同的围压、冲击次数和冲击能量对饱和吹填粉土进行动力固结,结合静三轴试验对比分析了不同的冲击荷载作用后试样强度的变化特征．结果表明：冲击次数和冲击能量是影响饱和粉土地基加固效果的重要因素,存在一个最佳的夯击方式,在该方式下强夯的效果最好．     

粉土强夯法地基处理参数的试验研究

某原料场工程采用强夯法对饱和粉土进行地基处理。针对该工程设计和施工中遇到的强夯参数和地基处理效果等问题进行试验研究,对该工程区域运用不同的强夯参数,通过加固过程中的夯坑沉降量、地面隆起量和孔隙水压力监测,以及加固后土层的静力触探、地基承载力等现场试验,对不同强夯参数下的加固效果进行比对,得出适用于该工程粉土地基的强夯参数。     

散货船底部纵骨防倾肘板节点疲劳优化研究

为了提高CSR(BC)规范下散货船底部纵骨在防倾肘板连接处的疲劳寿命,采用有限元法比较几种不同切口形式在热点处的应力集中系数,确定其中有效的几种形式,使用共同规范的直接计算法予以证明,为便于使用,针对这些切口形式给出在CSR(BC)简化计算法中可以参照使用的系数。     

Classification of underwater target echoes based on auditory perception characteristics

In underwater target detection, the bottom reverberation has some of the same properties as the target echo, which has a great impact on the performance. It is essential to study the difference between target echo and reverberation. In this paper, based on the unique advantage of human listening ability on objects distinction, the Gammatone filter is taken as the auditory model. In addition, time-frequency perception features and auditory spectral features are extracted for active sonar target echo and bottom reverberation separation. The features of the experimental data have good concentration characteristics in the same class and have a large amount of differences between different classes, which shows that this method can effectively distinguish between the target echo and reverberation.