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1.
SHUI-LONG SHEN XING-CHUN HUANG SHOU-JI DU JIE HAN 《Marine Georesources & Geotechnology》2013,31(1):15-35
This paper has identified six major factors causing property changes in surrounding soils during and after installation of deep mixing columns: soil thixotropy, soil fracturing, cement penetration and diffusion, cementation, consolidation, and heating. Laboratory tests were performed to investigate the effects of soil thixotropy, soil fracturing, and cementation in a soft marine clay, Ariake clay. Laboratory tests were conducted to evaluate property changes in surrounding clays due to installation of deep mixing columns. Test results showed that an influential zone of property changes existed in surrounding clay ranging from the edge of the columns to the distance of about twice the radius of the columns. Within this influential zone, water content decreased as samples neared the columns, while pH values and electric conductivity increased. Test results also showed that undrained shear strengths of the surrounding clays decreased during mixing but regained after a 7-day curing period and continued increasing during 28 days in this study. 相似文献
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Laboratory Studies on Property Changes in Surrounding Clays Due to Installation of Deep Mixing Columns 总被引：6，自引：0，他引：6
Shui-Long Shen Xing-Chun Huang Shou-Ji Du Jie Han 《Marine Georesources & Geotechnology》2003,21(1):15-35
This paper has identified six major factors causing property changes in surrounding soils during and after installation of deep mixing columns: soil thixotropy, soil fracturing, cement penetration and diffusion, cementation, consolidation, and heating. Laboratory tests were performed to investigate the effects of soil thixotropy, soil fracturing, and cementation in a soft marine clay, Ariake clay. Laboratory tests were conducted to evaluate property changes in surrounding clays due to installation of deep mixing columns. Test results showed that an influential zone of property changes existed in surrounding clay ranging from the edge of the columns to the distance of about twice the radius of the columns. Within this influential zone, water content decreased as samples neared the columns, while pH values and electric conductivity increased. Test results also showed that undrained shear strengths of the surrounding clays decreased during mixing but regained after a 7-day curing period and continued increasing during 28 days in this study. 相似文献
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A simple numerical model, based on the Reynolds stress equations and k–ε turbulence closure scheme, is developed for the coastal wave and current bottom boundary layer. The current friction velocity is introduced to account for the effect of currents on waves. The implicit Crank–Nicolson finite difference method discretizes the governing equations. Vertical changing step grids with the constant ratio for two adjacent spatial steps are used together with the equal time steps in the modeling. Vertical profiles of mean current velocity and wave velocity amplitude are obtained. These modeled results are compared with the laboratory experimental data of Van Doorn [1981. Experimental investigation of near bottom velocities in water waves with and without a current. Report M1423, Delft Hydraulics Laboratory, Delft, The Netherlands; 1982. Experimenteel onderzoek naar het snelheidsveld in de turbulente bodemgrenslaag in een oscillerende stroming in een golftunnel. Report M1562, Delft Hydraulics Laboratory, Delft, The Netherlands]. It has been shown that modeled and observed (Van Doorn, T., 1981. Experimental investigation of near bottom velocities in water waves with and without a current. Report M1423, Delft Hydraulics Laboratory, Delft, The Netherlands; 1982. Experimenteel onderzoek naar het snelheidsveld in de turbulente bodemgrenslaag in een oscillerende stroming in een golftunnel. Report M1562, Delft Hydraulics Laboratory, Delft, The Netherlands) mean velocity profiles within the wave and current bottom boundary layer are in better agreement than outside. Modeled and observed (Van Doorn, T., 1981. Experimental investigation of near bottom velocities in water waves with and without a current. Report M1423, Delft Hydraulics Laboratory, Delft, The Netherlands) wave velocity amplitude profiles within the wave and current bottom boundary layer are in better agreement than outside. Modeled wave velocity amplitudes are in good agreement with the laboratory experimental data of Van Doorn [1982. Experimenteel onderzoek naar het snelheidsveld in de turbulente bodemgrenslaag in een oscillerende stroming in een golftunnel. Report M1562, Delft Hydraulics Laboratory, Delft, The Netherlands]. 相似文献
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Tao Liu San-Peng Li Hai-lei Kou Wan-li Chai Guan-li Wei 《Marine Georesources & Geotechnology》2013,31(7):775-782
AbstractFiber Bragg Grating (FBG) technology has emerged as a relatively new sensing technology for engineering applications because of lots of advantages. In this study, a large diameter probe instrumented with FBG pressure sensors to monitor excess pore pressure in marine sediment is proposed. The principle of FBG differential pressure sensor was introduced. Laboratory tests were carried out to check the workability and stability of the FBG pressure sensor. Offshore field test was also conducted in a wharf in Qingdao of China to evaluate the feasibility of the proposed probe. The installation procedure of the probe was introduced in detail. The excess pore pressure in dissipation test, after installation and pulling process were reported. The permeability coefficient of marine sediment was calculated based on the measured data. The field data show that the proposed probe based on FBG pressure sensor has good feasibility and accuracy in monitoring the excess pore pressure of marine sediment. The generation and dissipation of excess pore pressure is closely related to the degree of soil disturbance. The variation of excess pore pressure after installation can reflect the tide well in the site. 相似文献
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Laboratory analysis of core samples from the western Alboran Sea slope reveal a large variability in texture and geotechnical properties. Stability analysis suggests that the sediment is stable under static gravitational loading but potentially unstable under seismic loading. Slope failures may occur if horizontal ground accelerations greater than 0.16g are seismically induced. The, Alboran Sea is an active region, on which earthquakes inducing accelerations big enough to exceed the shear strength of the soft soil may occur. Test results contrast with the apparent stability deduced from seismic profiles. 相似文献
7.
Feng Bojun Huang Guoliang Liu Tianwei
Associale Professor Shanghai Jiao Tong University Shanghai Engineer Shanghai Jiao Tong University Shanghai 《中国海洋工程》1995,(4)
Articulated buoys become more and more popular by the marine management departments as a new type of aids to navigation, for they possess an excellent hydrodynamic performance with small static heel angle in wind and current and small rolling in wave and accurate position. The structure of articulated buoys and calculation method of their hydrodynamic performance are introduced in this paper. A scries of experiments has been conducted in the State Key Laboratory of Ocean Engineering of China and useful results achieved for providing a design optimization basis. 相似文献
8.
一种新型便携式旋桨流速仪 总被引：1，自引：0，他引：1
介绍了一种新型BH-1型便携式旋桨流速仪,主要由自主研制的流速传感器、手持式主机及微机数据回放处理软件三部分组成.其传感器采用独特的导流筒和导流罩结构设计,增加了系统的抗干扰能力,有效提高了测量准确性.应用单片机技术实现了数据的实时检测与处理,多路存储以及瞬时测量流量功能.通过静态试验标定,表明该流速仪测量范围(0.04～4)m/s,非线性误差为0.874%.该流速仪结构新颖、使用轻巧方便、稳定可靠,已广泛应用于国家海洋局对陆源入海排污口排污监测和海洋环境管理工作中. 相似文献
9.
P. G. Collar 《Ocean Engineering》1978,5(3):181-196
The measurement of near-surface current in the open sea presents difficult problems, of both sensor design and mooring in the surface wave field. However, knowledge of such currents is of considerable importance in research and offshore engineering. Consequently the development of an acoustic surface current meter has received particular attention within an experimental data buoy project which has been undertaken in the United Kingdom (DB1 Project). The development of any new sensor is necessarily followed by a thorough analysis of its performance, and it is this aspect to which this paper is devoted. The first part describes an experiment in which the displacements of drifting floats, tracked acoustically, were compared with the integrated output from the acoustic current meter: also a comparison with a buoy-mounted electromagnetic sensor. The extent of agreement between these different techniques is examined.A subsequent part discusses some longer term aspects of the performance of the current meter, which has operated almost continuously for 18 months at a test site close to the east coast of England. 相似文献
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矢量传感器是一种新型水声传感器。介绍了应用矢量传感器确定目标方位的理论和方法，给出了仿真和实验研究结果，讨论了矢量传感器具体体积小、输出信号多、抗各向同性干扰等特性。最后定性地分析了目标方位的方位估值误差。 相似文献
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An acoustic correlation current profiler (ACCP) system is being developed to obtain vertical profiles of current velocities to ranges of approximately 1500 m. A single transmitter and a spatial array of eight receivers arranged in a novel geometry are employed to measure water mass displacement from receiver array cross-correlation functions. Test data from a shallow water ACCP operating at 76.8 kHz are presented and compared to model predictions as well as to velocity profiles obtained simultaneously during the tests from an adjacent acoustic Doppler current profiler. Additionally, predicted performance data for a lower frequency deep-water unit are presented 相似文献
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The impact of rain and spray on the ocean disturbs the sea surface and generates underwater ambient noise. The short scale roughness is influenced by impacting drops due to the momentum transfer. Radar and sonar signals are scattered by the short elements of the sea surface. Spray and rain impact change their characteristics, and consequently affect radar and sonar backscatter. In situ measurements of rain and spray impact are necessary to study their effects on the sea surface. Accurate sea measurements of rain momentum fluxes and drop size distributions are a complex problem, especially on buoys. A new measuring technique has been developed using hydrophones. Exposed to precipitation, these instruments are affected directly by the impact of rain. A drop falling on the hydrophone deforms its surface and is sensed by a piezoelectric transducer. The voltage output of the sensor is a rapidly decaying oscillation. The integral value of this signal is a measure of the drop momentum, and the drop size can be deduced. Laboratory studies of defined drops as well as field measurements of natural rain have shown that hydrophones can be used to determine drop momentums and drop size distributions. Based on simultaneous rain measurements by a Joss-Waldvogel Disdrometer and a hydrophone, an analytical function has been derived which relates drop size and hydrophone voltage output 相似文献
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Accuracies of the benthic acoustic stress sensor (BASS) and the proposed modular acoustic velocity sensor (MAVS) are evaluated. A simple model of the hydrodynamic sources of error for acoustic current meters is presented and compared with the measured performance of BASS in a tow-tank and in field deployments. The sources of error addressed include those due to ideal flow around the sensor cage, wake effects from the support structure and transducers, vortex shedding from the cage, and electronic zero-point offsets. Electronic error dominates at velocities less than 5-10 cm/s, while flow disturbance dominates at higher speeds 相似文献
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一种新型海洋环境长期连续监测系统及其防生物附着装置的设计 总被引：1，自引：0，他引：1
主要介绍了一种海洋环境连续监测系统的设计与实现。现有的水下监测仪器一般长时间放置在水下,不可避免地会遭受海洋生物附着和损坏,通常3个月到6个月左右需要清理或者更新一次。设计采用新型监测结构,将被测海水抽样到舱内进行相关参数的检测,检测完成后,将海水排回海中,舱内仪器采用消毒液和清水自动冲洗。通过这种方式,避免了海洋生物的附着和污染,检测仪器可以长期可靠地运行,减少了设备的维护次数,在海洋监测领域具有重要的意义。 相似文献
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电磁海流计在海洋调查和研究中起着非常重要的作用。当前被广泛应用的电磁海流计的传感器基本采用三种不同的结构形式：球形结构、盘形结构和环形结构。而三种结构形式的传感器具有各自不同的技术参数和性能。文章对不同结构形式电磁海流计传感器的特点进行简要的比较和分析。我们在研制和使用电磁海流计时，应根据不同的设计要求和特定的应用环境和条件，选择适当形式结构的传感器，力求得到良好的结果。 相似文献
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A new system for logging the geophysical properties of marine sediment cores allows both whole cores and split cores to be
measured in a nondestructive fashion. The current sensor configuration measures compressional (P) wave velocity (500 kHz),
bulk density (using gamma-ray attenuation), and magnetic susceptibility at user-defined sample intervals down the core. Split-core
logging gives more reliable results than whole core logging as it mostly eliminates core-slumping effects that can lead to
spurious results; it also gives higher resolution magnetic susceptibility readings.
Received: 16 May 1997 / Revision received: 24 October 1997 相似文献