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AbstractThe coastal area of Fujian Province in China is rich in both sea sand and sea mud. However, sea sand and sea mud are both unsuitable as direct filler materials for seawalls due to their poor geotechnical properties. To turn waste into a useful product, a mixture composed of sea sand and sea mud is proposed as a filler material for seawalls. The strength, compressibility, moisture sensitivity, and permeability of the mixture are investigated experimentally. The results show that when the mass ratio of sea sand to limed sea mud is 1:2, the mixture exhibits good engineering properties and can serve as a filler material for general engineering purposes in dry environments. To apply the mixture under saturated conditions, both cement and lime are used to improve the engineering properties of the mixture. The improvements in the properties increase with both the binding agent content and the curing time, and the improvement with the addition of cement to the mixture is better than that with the addition of lime. The engineering requirements of seawalls can be satisfied by adding cement, and the cement content can be chosen according to considerations of the construction period and engineering costs. 相似文献
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强夯在粉煤灰地基处理中的应用 总被引：1，自引：0，他引：1
粉煤灰海水湿排造陆是沿海地区粉煤灰利用的主要途径之一。但造陆以后属于软土地基，不能直接利用，必须对其进行地基处理，处理效果如何，需进行评价。本文研究强夯处理在青岛沿海粉煤灰排放区的应用，并采用载荷试验、圆锥动力触探试验、室内实验等多种方法对强夯处理效果进行检测。检测结果表明，强夯处理后粉煤灰地基土能够达到设计的150kPa要求，为海水湿排粉煤灰造陆地基处理方法的应用和处理效果检测提供了借鉴。 相似文献
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针对全国海域使用情况的监测需求,本文应用扩展的证据理论进行围填海区域检测,预设类别空间为{围填海,海水}。实验结果显示基于扩展的证据理论不仅能够较准确地检测出围填海区域,而且将浅海中的水下沙脊或小岛划分为不确定的未知类别。说明扩展的证据理论能够更好地完成围填海的检测,体现了扩展的证据理论解决实际问题的能力,同时,也为全海域的围填海监测提供了新的思路和扩展空间。 相似文献
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Considering the characteristics of seabed ground in coastal reclamation area, ultra soft clay improvement method by heavy tamping after rockfilling displacement was proposed combined with a case study. The improvement mechanisms of the method can primarily be attributed to rockfilling displacement (RD), dynamic compaction (DC), dynamic replacement (DR) and dynamic replacement and mixing (DRM). For the case study given in this article, heavy tamping construction program was proposed based on field pilot tests. Furthermore, the effectiveness of the proposed ground improvement method was verified through in situ plate load test, sand fill test and the analyses of observed settlement data. Thus, the method of heavy tamping after rockfilling displacement is applicable for the improvement of seabed ground in coastal reclamation area. It is proposed for similar projects that heavy tamping of fills may be performed by layers and correspondingly tamping energy increased to further enhance the improvement effect of DC, DR and DRM. In addition, delayed improvement effect or time effect of soil mass after heavy tamping is still an issue to be further studied. 相似文献
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Xin-Zhi Wang Feng-Yi Tan Yu-Yong Jiao Ren Wang 《Marine Georesources & Geotechnology》2013,31(4):379-386
Calcareous sand, widely spread on coral reefs in Nansha Islands, South China Sea, will be used as backfill material in oceanic engineering, but its engineering property is still elusive. It's difficult and extremely costly to conduct in-situ plate load tests to investigate the bearing capacities of calcareous soils foundation because the coral reefs are too far from the mainland and located in tidal zone. In order to study the bearing capacity and deformation behavior of calcareous soils, the authors designed an apparatus to carry out laboratory tests. The apparatus has the advantages as listed: (1) estimating the bearing capacity and deformation of soil foundation; (2) measuring the soil pressures and settlements at diffirent depths; (3) investigating the load transmission depth. Test results of calcareous sand indicate that the apparatus is suitable to test the engineering behavior of soil in laboratory. 相似文献
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基于高空间分辨率卫星遥感影像的围填海存量资源监测与评估研究——以营口市南部海岸为例 总被引：2，自引：0，他引：2
为详细掌握围填海存量资源状态,提高海域空间资源监管精细化水平,本文提出围填海存量资源概念,并将围填海存量资源划分为围而未填区域、填而未建区域、低密度建设区域、低洼坑塘、低效盐田和低效养殖池塘等6种类型,以及工业区、城镇区等围填海存量资源的消耗类型。在此基础上,采用高空间分辨率卫星遥感影像,建立了面向对象的围填海存量资源遥感影像分类提取方法与技术流程,构建了围填海存量资源指数,并以营口市南部海岸区域为例进行了实证研究。结果表明:（1）面向对象的围填海存量资源遥感影像分类提取方法能够精细地提取围填海存量资源信息,准确率达到90%以上;（2）填而未建区域、低效盐田、低效养殖池塘占研究区围填海存量资源总面积的62.51%,研究区围填海存量资源指数为0.49,但内部差异明显,北部区域为0.66,中部区域为0.44,南部区域为0.37。 相似文献
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Characterization of the hydraulic property of a specific geomaterial is of fundamental importance in engineering design and application. This paper reports an experimental investigation to the hydraulic conductivity of a typical marine sand, i.e., calcareous sand, which becomes increasingly popular as sea-filling material for land reclamation or construction of artificial islands. A series of permeability tests have been performed using the calcareous sand collected from Nansha islands in South China Sea. Using the home-made permeability test apparatus (so-called velocity-controlled pressure-differential acquisition flow apparatus), the relationship between flow velocity and hydraulic gradient was obtained and the hydraulic conductivity of calcareous sand was then determined accordingly. The effects of important parameters, including particle shape and particle size distribution on the hydraulic conductivity of calcareous sand, were assessed. To investigate the effect of particle size distribution on the hydraulic conductivity of calcareous sand, two often-used parameters, i.e., nonuniformity coefficient and curvature coefficient were considered in this study. To quantitatively evaluate the irregularity of soil particle, a particle-shape parameter was introduced and it was able to consider sphericity and circularity of highly irregular particle. Two materials, namely, Fujian quartz sand and glass beads consisting of particles of characteristic shape, were also used in the permeability tests, and they were used to compare with calcareous sand. Through the comparison, the effect of particle shape of calcareous sand on its hydraulic conductivity was examined based on the newly introduced particle shape parameter. The test results indicate that the particle size distribution has a significant influence on the hydraulic conductivity of calcareous sand. The quite irregular particle shape is able to reduce the hydraulic conductivity of the calcareous sand. A comparative study of hydraulic conductivity between the theoretical prediction and experimental measurement was performed, and it is concluded that an improvement of theoretical model for prediction of the hydraulic conductivity of the porous media consisting of particles with highly irregular shapes, such as the calcareous sand, is still required. 相似文献
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珠江口黄茅海拦门沙演变及成因分析 总被引：1，自引：1，他引：0
采用1977,1994,2003,2010年4个年份的地形图,建立了DEM模型,结合二维水动力模型对近30多年来黄茅海拦门沙演变的特征及成因进行了分析。研究表明近30多年来黄茅海拦门沙平面上向海推移,范围缩小,在内坡和拦门沙顶冲刷,在外坡淤积;拦门沙的基本成因是其位于上溯流与下泄流控制区域之间的过渡带,该过渡带为明显的动力较弱的区域,泥沙较易在此处沉积;黄茅海大面积的围垦导致纳潮量减少、潮汐动力减弱、径流作用相对增强,使下泄流控制区扩大、上溯流控制区减小、过渡区下移,这是拦门沙冲刷外移和缩小的主要原因。上游来沙量减少加剧了拦门沙冲刷外移和缩小。 相似文献
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Shi-Jin Feng Wei-Hou Shui Li-Ya Gao Li-Jun He 《Marine Georesources & Geotechnology》2013,31(2):130-142
High energy dynamic compaction (HEDC) is adopted in a coastal reclamation area because the grain size of backfilled soil mostly ranges between 20 cm and 100 cm. The in situ tests for evaluating the effectiveness of HEDC were performed on the backfilled soil ground. The crater depth per drop and the whole test zone elevations before and after HEDC were measured and analyzed. Dynamic penetration tests and spectral analysis of surface wave (SASW) tests were used for investigating the improvement depth. Furthermore, the allowable bearing capacity of HEDC treated ground was determined based on the results of plate-load tests. It was found that HEDC did not cause the ground surface heave during construction, and was more effective than low energy dynamic compaction (LEDC) in terms of applied energy utilization. Based on the test results, the improvement depth of HEDC at this site was not less than 14 m, and there was no obvious weak layer within the range of improvement depth. The allowable bearing capacities were larger than 160 kPa. The investigation results indicate that the HEDC technique is an effective way for improving backfilled coarse-grained soil in coastal reclamation areas. This technique helps to achieve both greater improvement depths and higher ground bearing capacities as compared with LEDC. 相似文献
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利用已经过验证的高分辨率三维海洋动力模型FVCOM,根据1984—2014年内伶仃洋的围填海变化情况,结合情景模拟案例,研究分析围填海对伶仃洋水流动力的影响,探究截流式和顺流式围填海对伶仃洋不同季节的水平余流场、垂向环流结构以及潮汐变化过程的影响。研究结果表明,围填海对伶仃洋的余流流向没有明显影响,但对余流速有较大的影响。在水平方向上,截流式围填海使得周边海域的余流速明显增大,增幅在0.02～0.25 m/s不等,其中口门区域受到的影响最大;相较于底层流场,表层流场受围填海的影响相对更大,围填海以南的较远海域在表层出现一条强度逐渐减弱的流速减小带,减幅在0.02～0.15 m/s不等,且影响范围与流场的分布密切相关,在夏季向南延伸,在冬季向西南延伸。顺流式围填海的影响则主要分布在伶仃洋两侧沿岸,并且不同季节的影响特点有一定区别,在夏季使得内伶仃洋东岸海域流速增大,但在冬季使其流速减小,变化幅度均在0.02 m/s以上。在垂直方向上,围填海使口门区域余流的纵向流速梯度增加,并且改变了伶仃洋余流的垂向分布情况,总体表现为远离围填海的海域表、底层余流的流速减小,中上层余流的流速增大;与此同时,围填海大幅度改变了周边海域的横向流速,并且在伶仃水道、矾石水道等区域产生了新的横向环流。围填海使得河口至围填海的余水位明显上升,使得伶仃洋海域的余水位下降,余水位梯度的增大是围填海周边余流速增大的主要原因。另外,围填海影响了伶仃洋的潮汐变化过程。在大潮期间,围填海改变了伶仃洋海域涨落潮时的潮流流速,使得周边海域落急流速增加,较远海域落急流速减小,而涨急流速都减小;同时,围填海使得海域涨落潮时的潮位受到一定影响。围填海最终使得伶仃洋的潮汐相位提前了20～35 min。 相似文献
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利用Google Earth(GE)遥感影像资料,完成了对世界沿海国家的围填海分布及平面设计特征的研究。研究表明:世界围填海主要分布在4大区域,即东亚、波斯湾、欧洲西部和北美沿岸;中国的围填海总量最多,平均粒度第二;4大区域的围填海平面形态呈现规律性,东亚填海基本以几何形状居多,波斯湾填海多为仿自然形态,欧洲西部填海善于利用地理区位优势,北美填海有大量突堤游艇码头。讨论了造成围填海平面形态区域差异的原因及本次研究的优缺点,可为围填海管理和围填海平面设计研究提供方法支持。 相似文献
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Jijian Lian Hongyin Xu Xiaoqing He Dengfeng Fu Shuwang Yan 《Marine Georesources & Geotechnology》2013,31(2):212-222
ABSTRACTBiogrouting, which is a new method for soil improvement, was used in an attempt to cement a type of hydraulic fill fine sands (called black sands) in reclamation projects in Tianjin, China, to form a working layer for mechanical equipment. Several factors influencing biogrouting with regard to cementing solution, including injection frequency, reaction time, concentration, and flow rate, were controlled to prepare black sand columns. This paper reports on an investigation of bacterial fixation, calcium ion utilization, and calcium carbonate distributions of biogrouted sand specimens. At the end of the tests, the geotechnical performances of the sand specimens were determined. The results showed that the biogrouting method effectively solidified black sands, by increasing the unconfined compressive strength of a sand column to 1.91?MPa and reducing the permeability coefficient by three orders of magnitude. A relationship between the unconfined compressive strengths and calcium carbonate contents was put forward, in addition to a relationship between the permeability coefficients and the calcium carbonate contents. According to the experimental results, some reasonable suggestions regarding the application of biogrouting to the consolidation of hydraulic fill fine sands in reclamation projects were proposed. 相似文献
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围海工程对邻近港区泥沙回淤的影响研究—以漳州港招商局中银码头区为例 总被引：5，自引：0，他引：5
针对港区附近围海造地造成的港区泥沙回淤量增大问题，以漳州港招商局中银码头区为例，全面分析了漳州港海域的地形地貌、水动力特征、泥沙特性和岸滩自然演变。根据工程建设前后地形变化，结合岸线回填量和九龙江输沙资料，分析了围海造地对岸滩演变及港区码头回淤的影响。研究表明，围海工程实施后，邻近港区的泥沙回淤由自然回淤、滩地抬高和回填引起的浑水回淤三部分组成。当围海工程结束，新岸滩调整达平衡后，泊位及港池的回淤将逐渐降至正常自然回淤强度。 相似文献
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潮滩既具有重要的生态服务功能,亦是潜在的土地资源。过去几十年来,中国沿海潮间带的开发以围垦为主要驱动力,表现为海岸线主体向海推进。随着围垦规模和速度加快加大,出现了一系列生态、环境及土地利用问题,因此对于围垦适宜性的研究具有现实意义。本文以浙江省为例,利用遥感技术首先获取了大陆海岸线阶段性变化特征。接着从地貌均衡的角度,依据潮滩垂向淤涨速率和垂直岸线的潮滩剖面形态估算适宜的潮滩围垦速率。最后,比较海岸线实际推进速率与估算所得的围垦适宜速率,进行围垦适宜性分级评价。研究表明,1985-2015年间,围垦活动是浙江省大陆海岸线向海推进的主要原因。从时间进程来看,1985-1995年浙江省大陆海岸线向海推进缓慢,受围垦活动影响较小;1995-2015年间围垦活动频繁,人工岸线比例增加较多。围垦适宜速率的估算显示,杭州湾南岸围垦1 km后所需恢复时间最短,围垦适宜速率为12.5～64.3 m/a,其次为象山港和台州湾,围垦适宜速率分别为2.0～38.3 m/a和6.0～22.2 m/a;三门湾和温州湾围垦后所需恢复时间最长,围垦适宜速率分别为1.2～18.5 m/a和1.7～3.8 m/a。基于潮滩淤涨速率的围垦适宜性评价表明,1985-2015年间,浙江省主要围垦区域中围垦速率过快的是三门湾的下洋涂、蛇蟠岛和温州湾岸段,围垦速率较快区域为杭州湾南岸庵东浅滩部分岸段和象山港的莼湖镇、涂茨镇岸段以及台州湾的南洋涂,围垦速率略快的是庵东浅滩以及台州湾的北洋涂,围垦速率适宜的岸段仅有象山港的高湖塘和蒲门村岸段。浙江省过去30年的围垦进程和岸线变化启示,围垦活动应充分考虑潮滩环境的地貌动力均衡和自然恢复潜力。 相似文献
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珠江口滨海湿地退化现状、原因及保护对策 总被引：1，自引：0，他引：1
2007年和2008年秋季对珠江口滨海湿地进行了环境现状综合调查,结果表明,珠江口滨海湿地退化主要表现在4个方面:天然湿地面积减少、湿地生产力不断下降、湿地环境状况持续恶化和湿地景观破碎化。珠江口滨海湿地退化的原因主要为滩涂开发与围填海、污染物排放、养殖污染、海平面上升、过度捕捞、海砂开采和港口码头建设以及水土资源开发等因素。滨海湿地保护与利用对策主要有:制定有关滨海湿地保护的法律法规和湿地保护与利用规划;加强人才队伍建设和滨海湿地有关技术研究;建立滨海湿地动态监测体系;加大滨海湿地保护区建设的力度;加强宣传和教育。 相似文献