共查询到20条相似文献，搜索用时 750 毫秒
1.
围海造陆填土技术及其应用研究 总被引：1，自引：0，他引：1
《中国海洋大学学报(自然科学版)》2015,(6)
提出了在填土工程中将海底的淤泥和吹填料中的淤泥聚集在一起,最终将新形成的陆域分离成以粗粒土为主的非软土地基和以淤泥质土为主的软土地基两个区域,继而可以针对各分区的地基选用不同的加固处理方法的围海造陆填土技术观点;基于土力学的强度理论和水力吹填的分选性,提出了能够实现填土技术观点的思路与基本条件;将本文提出的围海造陆填土技术观点、陆域形成填土技术成功应用于日照岚山港区围海造陆工程。 相似文献
2.
在淤泥质软弱地基上的海港码头,以往的实践经验是采用高桩结构.但建设地附近砂石材料丰富,施工单位不具备搞桩基码头的设备和技术力量,而对重力式码头则有较成熟的施工经验,这样,在设计上考虑挖除部分淤泥质土,换以砂,采用底宽稍大的空心方块和空斗胸墙;在施工中采取施工顺序分段平行,控制加荷速率等措施,使淤泥质软弱地基的承载力仅为8t/m~2的情况下,建造重力式码头成为可能。 相似文献
3.
搜集汇总黄河口埕岛海域地质勘察资料,研究该区土性参数区域分布特征,包括分析海域内土体类别,绘制不同区域内地基承载力、标贯击数、粘粒含量、含水量、孔隙比和液塑限等值线图.研究发现,海域表层土体主要由粉土和粉质粘土组成,此外还有小面积的粉砂和淤泥质土,中部大面积地区为粉土,东南区域分布有粉质粘土和淤泥质土;地基承载力较高的区域主要分布在海域中部与西南部,海域的北部与东南部土体强度较低,并且含水量、孔隙比和液塑限也较大,土性区域变化与水深变化特性较为一致.最后分析土性区域变化机理认为,极端海况下该区土体发生液化剪切破坏,沿斜坡滑移运动一定距离后再次沉积可形成这种现象. 相似文献
4.
5.
基于孔压监测的强夯置换和砂井-强夯处理饱和软土地基试验研究 总被引：1，自引：0，他引：1
在青岛某饱和软土场区采用强夯置换和砂井-强夯2种不同方案进行试夯试验。在试验区距夯点不同距离、不同深度的土层中埋设孔隙水压力计,通过观测,分析试夯过程中超孔隙水压力的变化规律,得出以下结论:2 000~2 500kN·m夯击能作用下,点夯试验最佳夯击数为强夯置换14击、砂井强夯16击,且2种方案强夯有效加固深度均可达6m;强夯置换区块距离夯点越近,超孔隙水压力累积幅值越大,而砂井-强夯区块这一趋势则不明显;砂井-强夯区块较强夯置换区快地基具有更好的均匀性,但其夯后超孔隙水压力消散速度比后者慢;孔压监测是确定强夯参数,了解加固深度,评价加固效果的有效手段。 相似文献
6.
在青岛娄山河污水处理厂使用强夯法对粉煤灰地基进行处理,通过定量计算分析强夯前后土工试验、原位测试结果,评价粉煤灰物理力学性质的改善状况;分析原位测试试验成果之间的内在联系,对强夯法加固粉煤灰地基的效果评价进行了初步研究。结果显示,强夯有效加固深度内的粉煤灰层物理力学性质发生了明显改善,但其孔隙比仍大于1.0;点夯过程宜及时排水,以提高夯实效率。本文研究结论对粉煤灰地区的加固具有一定的指导和参考意义。 相似文献
7.
根据现场大风浪条件下的实测资料,粉质土海岸水体中的含沙量沿垂向具有上部均匀、近底突增的分布特点,即呈L型分布特征。利用黄河三角洲粉质土作为试验底床开展波浪水槽试验研究,揭示了底床粉质土在波浪作用下产生液化情况的水体含沙量沿垂向存在L型分布特征。根据试验现象以及悬沙粒度变化,分析认为底部高含沙层的形成主要受粉质土液化后细颗粒析出的影响,上部水体中悬沙由湍流脉动维持。对粉质土海岸大风天气期间水体含沙量剧烈增加采用波致粉质土液化的观点进行了初步解释。 相似文献
8.
山东全新世滨海软土与工程地质灾害的研究 总被引：2，自引：0，他引：2
吴建政 《海洋地质与第四纪地质》1995,15(3):43-54
山东全新世滨海软土分布在海湾、泻湖、河口区，厚度１－１０ｍ。海湾、泻湖软土为淤泥、淤泥质土，陆源物质供应丰富的浅水区，软土颗粒偏粗，强度相对较高，触变性对建筑物危害性大，陆源物质供应少的深水区，软土颗粒偏细，低强度、高压缩性、沉降变形大和蠕变性是危及建筑物稳定的主要因素。海湾、泻湖软土位于地下水位下，具低透水性，掩埋后短期不易排水固结，软土下为强度较高的冲积物，对一般建筑物，利用强夯、粉喷搅拌桩、 相似文献
9.
10.
11.
12.
Hongyue Sun Gang Wu Xin Yan Dongfei Wang Zhenlei Wei 《Marine Georesources & Geotechnology》2018,36(8):940-949
Conventional drainage consolidation methods cause significant energy consumption and environmental issues. In this paper, a method combining siphon drainage and surcharge loading is proposed to drain water from soft soil with vertically installed prefabricated vertical drains (PVDs) and a siphon tube. To investigate the availability and effectiveness of this method, a laboratory physical modeling test was conducted to investigate the drainage and consolidation behavior. The laboratory modeling test results of this method were compared with the calculated results of the ideal sand-drained ground consolidation method to clarify the advantages and mechanism of this method. Comparison results show that the pore pressure and settlement in the proposed method developed faster than the calculation results of ideal sand-drained consolidation theory. About 10?m thickness of unsaturated zone can be formed by siphon drainage which produce a surcharge loading effect on the soil below the flow profile. Drainage is a very slow process in soft soil, and siphon drainage can work continually. Siphon drainage combined with surcharge loading is potentially a good alternative to drain water from soft clay economically and environmentally. 相似文献
13.
Guo-Wei Li Thang Ngoc Nguyen Andrew Cudzo Amenuvor 《Marine Georesources & Geotechnology》2016,34(2):154-161
This article studies the effect of dynamic cyclic loading and surcharge preloading method on the post-construction settlement of low embankments. Soil samples obtained from the soft ground under an embankment were consolidated by surcharge preloading followed by static and dynamic cyclic loading in the odometer. The results show that the consolidation deformation of the soil samples is independent of the frequency of the dynamic cyclic loading, which was simulated to follow the half-sine wave, and this is consistent with the energy concept. The post-construction settlement increases with increasing amplitude of cyclic load and the effectiveness of surcharge preloading depends on the difference between magnitude of surcharge and amplitude of the cyclic load. Based on the consolidation theory combined with the test results, a formula has been proposed to compute the post-construction settlement of a low embankment under cyclic loading. 相似文献
14.
YAN Shuwang FANG Shouzhong Professor Dept. of Hydraulic Engineering Tianjin University Tianjin P. R. China. Graduate Student Dept. of Hydraulic Engineering Tianjin University Tianjin P. R. China. 《中国海洋工程》1998,(2)
Vacuum loading has been examined as a way of preparing uniformly consolidated soft claysamples.The facility and loading procedure are described in this paper.An analytical solution to the threedimensional consolidation equation is derived for estimating the degree of consolidation of the soil samplewith vacuum loading.The given example shows that the predicted degree of consolidation of a soft claybulk with vacuum loading is close to that measured in the consolidation process. 相似文献
15.
16.
Huayang Lei Haibin Lu Xuechao Wang Qian Ren Bin Li 《Marine Georesources & Geotechnology》2016,34(4):365-375
The accelerated rheological properties of natural soft clay are the external power and predisposing factors of geological and geotechnical disasters. To determine the changes in soil micro-structure for natural soft clay under accelerated creep condition, a detailed study has been carried out using consolidated undrained tri-axial tests under static and cyclic loads, as well as experimental data from mercury intrusion porosimetry and a scanning electron microscope. In the tri-axial tests, creep of the soft clay would be accelerated under dynamic loads, the sample would be destroyed faster, and the strain-rate would increase clearly along with the increase of the vibration frequency. Based on a comparison of micro-structure behaviors between the intact sample and the test soil samples under static and dynamic loads in the creep condition, an interpretation of the changes in soil micro-structure for natural soft clay under an accelerated creep condition was proposed. The research indicated that the large pores of the soil sample gradually changed into small pores, the large particles continuously changed into tiny particles, and the pore distribution gradually became uniform under dynamic loads. It was found that the fractal dimension of the pores decreased with the increase of the vibration frequency. The test results not only showed that the accelerated creep characteristics depended on the vibration frequencies of the applied dynamic loads, but the accelerated creep was actually an unceasingly self-adjusting and reengineering process of the internal structure in soil under dynamic loads. In addition, these results revealed that there was a close relationship between the vibration frequencies and the micro-structure parameters. 相似文献
17.
Plastic vertical drainage is widely used in vacuum preloading for soft soil treatment. However, plastic vertical drainage has a number of disadvantages such as it only provides drainage paths in vertical directions and the distribution of soil strength is not uniform. A new technique, prefabricated vertical–horizontal drainage, was developed in this study to shorten the consolidation time of ultrasoft soil. Using one vertical drainage tube and four horizontal drainage tubes, prefabricated vertical–horizontal drainage provides drainage paths not only in vertical but also in horizontal directions. An analytical solution was derived to calculate the degree of soil consolidation when using the prefabricated vertical–horizontal drainage technique. Field tests were conducted to evaluate the effectiveness of prefabricated vertical–horizontal drainage and to verify the proposed analytical solution. It was found that consolidation time of soft clays using prefabricated vertical–horizontal drainage was 50% lower than plastic vertical drainage. Moreover, the average undrained shear strength of soil treated by the prefabricated vertical–horizontal drainage technique was approximately 30% larger than that treated by the plastic vertical drainage technique. The degree of soil consolidation estimated from the proposed analytical solution showed good agreement with field measurements. This implies that the proposed analytical solution can be used to directly estimate the degree of consolidation when the soil is treated by prefabricated vertical–horizontal drainage. 相似文献
18.
Stiffness degradation will occur due to the generation of accumulated pore pressure in saturated soft clays under cyclic loading. The soil static-dynamic multi-purpose triaxial and torsional shear apparatus in Dalian University of Technology was employed to perform different types of test on saturated soft marine clay in the Yangtze estuary. Undisturbed samples of the clay were subjected to undrained cyclic vertical and torsional coupling shear and cyclic torsional shear after three-directional anisotorpic consolidation with different initial consolidation parameters. Investigated were the effects of the initial orientation angle of the major principal stress, initial ratio of deviatoric stress, initial coefficient of intermediate principal stress and continuous rotation of principal stress axes on the stiffness degradation. It is found that the degradation index decreases (or degradation degree increases) significantly with increasing initial orientation angle of the major principal stress and initial ratio of deviatoric stress. Compared to the effects of the initial orientation angle of the major principal stress and initial ratio of deviatoric stress, the effect of initial coefficient of intermediate principal stress is less evident and this trend is more clearly reflected by the results of the cyclic torsional shear tests than those of the cyclic coupling shear tests. At the same cycle number, the degradation index obtained from the cyclic torsional shear test is higher than that from the cyclic coupling shear test. The main reason is that the continuous rotation in principal stress directions during cyclic coupling shear damages the original structure of the soil more than the cyclic torsional shear does. Based on a series of experiments, a mathematical model for stiffness degradation is proposed and the relevant parameters are determined. 相似文献
19.
A seabed-type of breakwater applicable to very soft ground without the need for soil improvement is newly developed. This type of soft-ground breakwater is expected to ensure sufficient lateral resistance and prevent excessive consolidation settlement due to self-weight of the breakwater. In this paper, lateral and consolidation behaviors of soft-ground breakwater were investigated by performing model tests and finite element simulations. The results revealed that the bottom wall and buoyant box, which are the main features of soft-ground breakwater, contribute to the increase in lateral resistance and to the control of the consolidation settlements, respectively, and that Terzaghi's consolidation theory could be conservatively adopted in deriving the consolidation settlements of soft-ground breakwater proposed herein. 相似文献
20.
1 .IntroductionTheZhapuPortissituatedonthenorthbankoftheHangzhouBay ,nearZhapuTowninPinghuCity ,Zhejiangprovince .Asthefirststepofconstruction ,reclamationwasaccomplishedinthehinter landoftheharbor.Theborderdikeofafulllengthof 1 2 71mislocatedinthetidalregionoftheHangzhouBay .ThepreliminarydesignofthisprojectwascompletedinJune 1 986 ,anditsconstructionbeganinJuly 1 986 ,andwascompletedinMarch 1 991 .TheseadikewasbuiltontheQ4marinedepositofsaturatedsoftclaywithathicknessofabout2 7mandgeo… 相似文献