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1.
M. Hashemi M. R. Nikoudel N. Hafezi Moghaddas M. Khamehchiyan 《Arabian Journal of Geosciences》2014,7(6):2339-2352
A broad assessment of the geological, sedimentological, and geotechnical characteristics of the coastal Holocene sediments of Anzali Area (North Iran) was made to provide a useful guide for development, planning, and construction. Based on the sedimentological and geotechnical properties of the sediments, three engineering geological units as Upper Sandy Zone (USZ), Middle Clayey Zone (MCZ), and Lower Sandy Zone (LSZ) were identified and introduced in the form of an engineering geological model. Then the engineering geological characteristics of the units of the model were analyzed and the main engineering geological problems associated with the deposits of each unit were identified. The results showed that USZ has high liquefaction potential, low bearing capacity, settlement susceptibility, and excavation problem; MCZ has low-bearing capacity as well as high settlement susceptibility and excavation problem; and LSZ has good geotechnical properties, then it poses few problems. 相似文献
2.
西太平洋暖池区是指位于热带西太平洋及印度洋东部海表温度常年在28 ℃以上的海域,是全球海表温度最高的深海区,构造环境与沉积环境复杂,沉积物中的生物组分含量差异较大,生物组分会对深海沉积物物理力学性质产生显著影响,但目前对沉积物中生物组分含量和沉积物物理力学性质之间的相关性关系尚不明确。本文对西太平洋暖池区核心部位的表层沉积物样品进行现场物理力学性质测试和室内涂片鉴定,研究深海表层沉积物的物理力学性质与生物组分之间的关系。结果表明:研究区表层沉积物含水率范围为61.1%~435.1%,天然密度范围为1.04~1.76 g/cm3,贯入阻力范围为0~100 kPa,十字板剪切强度范围为0~8.6 kPa,整体具有高含水率、低密度、低强度等典型的深海沉积物物理力学性质特点。西加洛林海脊、海山等CCD以浅的区域为钙质生物组分>50%的钙质沉积区;西加洛林海槽西南部及其周边的深水沟槽地区一般为硅质生物组分>50%的硅质沉积;西加洛林海盆内部则主要为黏土沉积区。随钙质生物组分减少和硅质生物组分增多,表层沉积物类型分别为钙质沉积物、黏土沉积物和硅质沉积物,天然含水率变高,天然密度、贯入阻力和十字板剪切强度降低,表明深海表层沉积物的物理力学性质与生物组分含量密切相关:贯入阻力、十字板剪切强度、天然密度与钙质生物组分含量呈正相关,与硅质生物组分含量呈负相关;而天然含水率正好相反,与钙质生物组分含量呈负相关,与硅质生物组分含量呈正相关。本文建立了深海沉积物中生物组分与物理力学性质之间的相关关系,提出了沉积物生物组分含量与物理力学性质之间的拟合公式,可以为深海沉积物工程性质的评价提供参考。 相似文献
3.
海洋工程建设已步入深海,但与之匹配的浅表层沉积物不排水剪切强度原位测试技术尚不成熟。为此,本文开发了可用于评估深海浅表层沉积物土力学性质的多探头原位测试系统,包括锥形触探仪、球形贯入仪和十字板剪切仪,可实现对深海沉积物土力学性质的快速、准确和智能化评价。进一步,通过CEL大变形数值模拟和足尺土工模型试验确定锥形触探仪的锥尖阻力系数,基于离心模型试验给出球形贯入仪的贯入阻力系数,从而完善深海浅表层沉积物不排水剪切强度的评价方法;在此基础上,探讨3种特定仪器各自适合的强度测试区间。结果表明:对于深海浅表层沉积物不排水剪切强度的评估,锥形触探仪和球形贯入仪的阻力系数建议分别取值为9.5和11.1。 相似文献
4.
Geotechnical property analyses on sediments recovered by DSDP drilling within select convergent margins were integrated to determine the variability in these properties along the trench inner-slope and to delineate the effects of convergence on these properties. Consolidation states range from very underconsolidated to highly overconsolidated, with preconsolidation pressures exceeding 46,000 kPa in Quaternary sediments. Underconsolidated sediments are attributed to:
- 1. (1) high sedimentation rates.
- 2. (2) low sediment permeability relative to the length of the drainage path; (3) laterally applied stresses; and (4) induced pore water pressures resulting from the subduction of pelagic sediments with high water content. Factors contributing to the state of overconsolidation include: (1) tectonically induced overpressures; (2) removal of overburden by mass movement processes.
- 3. (3) low sediment accumulation rates.
- 4. (4) age.
5.
Knowledge about the marine sediment acoustic properties is a key to understanding wave propagation in sediments and is very important for military oceanography and ocean engineering. We developed a hydraulic-drived self-contained in situ sediment acoustic measurement system, and measured for the first time the in situ acoustic properties of sediments on 78 stations in the Yellow Sea, China, by employing this system. The relationships between the in situ measured acoustic properties and the onboard or laboratory determined geotechnical parameters were analyzed. Porosity was found to be the dominant factor in reducing velocity in a quadratic fashion; velocity showed an increment with bulk density and a decrement with mean grain size and clay content both with a nonlinear dependence; acoustic attenuation showed a bell-shaped correlation with porosity and mean grain size but reduced with clay content of the sediments. The attenuation results indicate that intergrain friction rather than viscous interactions between pore fluid and solid grains is the dominant loss mechanism in our marine sediments. The relationships established would be used to predict the geotechnical parameters from in situ measured acoustic properties and vice versa, as well as being an indicator of the seafloor processes, potential gas bubbles hazard and gas hydrates resources or other suitable targets of acoustic surveys. 相似文献
6.
Rolando P. Orense Andrew Zapanta Jr. Akinori Hata Ikuo Towhata 《Geotechnical and Geological Engineering》2006,24(1):129-161
Recent volcanic eruptions at Mt. Unzen (Japan) in 1990 and Mt. Pinatubo (Philippines) in 1991 produced voluminous amounts
of ash and sediments which inundated widespread areas. In later rehabilitation and reconstruction, it is practical and economical
to use these freshly deposited sediments as materials for foundations and embankments. However, the geotechnical properties
of young volcanic products have not been fully investigated. Accordingly, we investigated the geotechnical characteristics
of volcanic soils associated with three recent eruptions, namely, the Unzen and Izu-Oshima eruptions of 1990 and 1986, respectively,
in Japan and the Pinatubo eruption of 1991 in the Philippines. We specifically investigated index properties, permeability
and compaction characteristics, and strength and deformation behavior in drained conditions. Additionally, we examined the
dynamic properties and liquefaction characteristics of samples taken from Mt. Pinatubo. The results showed that the geotechnical
characteristics of the deposits generally varied with the sampling sites. Depending on the location, either upstream or downstream
from a volcano, the preferential sizing due to alluvial deposition affects engineering properties of the deposits. For example,
volcanic sediments upstream from Mt. Pinatubo have high compressibility and low cyclic strength, whereas those taken downstream
show dilative tendencies and high liquefaction strength. 相似文献
7.
A numerical technique, based on a mathematical programming algorithm, is presented for the solution of geotechnical problems where elastic-plastic material behaviour is considered. The proposed approach can be adopted for geotechnical media characterized by any suitable yield condition, accounting, if necessary, for workhardening behaviour. The loading process is subdivided into a series of steps applied to a finite element mesh with geometry and material properties constant along each step, but with possible changes between subsequent steps. As an application some typical geotechnical problems are analysed by means of the proposed algorithm and a comparison is made between the available in situ measurements and the numerical results. 相似文献
8.
The Dead Sea Basin is the lowest point on earth and is tectonically subsiding. During the Holocene Period the climate became much drier with increasing evaporation whereby initially lacustrine sediments were deposited from the non-marine brines, giving a multi-layered stratigraphy of lime carbonate and halite sediments. The lime carbonate sediments are comprised of laminated, clay to silt sized, clastic sediments (calcite) and authigenic aragonite and gypsum. The halite commonly appears as rock salt. Chemical industries, based on harvesting the salts from the Dead Sea, have developed on both the Israeli and the Jordanian sides of the basin. The lime carbonate soils are used for dike construction, and these soils, together with significant salt layers, are encountered in the foundations of structures, dikes, and tailings dams, requiring definition of their geotechnical properties. Use of standard soil mechanics definitions and testing approaches for the lime carbonates have been found inapplicable, particularly in view of their exceptionally high saline content, and it has been necessary to develop new concepts. The rock salt is encountered at shallow depths, with unit weights considerably lower than those usually discussed in the literature, and with correspondingly different mechanical properties. The geotechnical properties of these soils, and approaches used to define them, are discussed in the paper. 相似文献
9.
天然气水合物的开采会带来一系列的岩土工程问题,为了保障相关工程设施的安全,有必要建立一个合理的水合物沉积物本构模型。通过深入分析水合物沉积物力学特点,从颗粒间的作用机制出发,认为水合物沉积物的力学响应是沉积物中土体颗粒间摩擦与水合物胶结二者共同作用的结果;考虑到摩擦与接触特性不同的力学机制,分别采用修正剑桥模型和弹性损伤模型对土体骨架及水合物胶结的应力-应变关系进行描述;通过假定水合物胶结的损伤演化规律,并认为在受力变形过程中二者的应变始终相等,初步建立了一个水合物沉积物的弹塑性损伤本构模型。不同水合物饱和度沉积物应力-应变曲线的模型预测结果与室内三轴排水试验结果吻合良好,表明了所建模型的可行性和合理性。 相似文献
10.
11.
南黄海海区被认为是我国在海上进行公益性、战略性油气资源评价的有利海区,但目前该海区海底深度方向上沉积特征及工程地质特性的研究仍较少。本文利用2009年6月及2010年6月在南黄海中西部海底获取的287个站位的沉积物柱状样品,通过粒度分析、物理力学性质测试,得到了该海域海底的空间沉积特征及沉积物工程地质特性:研究区海底表层沉积物类型多样,西南海底以粉砂质砂、砂质粉砂为主,力学强度较高,不易压缩,但由于较强的水动力条件,易冲刷粗化;东北海底以粉砂质黏土、黏土质粉砂为主,力学强度低,极易压缩;研究区海底深度方向上沉积物类型并非单一,常由几种类型沉积物互层组成,沉积物基本物理性质和力学性质随埋深变化的情况主要与沉积物类型有关,其次是压实作用。一定程度上,可利用本文给出的拟合函数,通过压缩波速估算研究区海底沉积物的孔隙度。 相似文献
12.
A Combined Three-Dimensional Geological-Geostatistical-Numerical Model of Underground Excavations in Rock 总被引：1，自引：1，他引：1
Summary. This paper exploits geological and borehole geotechnical data obtained in the exploratory phase of a tunneling project to
investigate in a first place if the kriging interpolation scheme may effectively reproduce the spatial variability of rock
mass quality (Rock Mass Rating, RMR) in the vicinity of tunnels. For this purpose a quick solver in Fortran has been developed
that performs variography analysis of 3D spatial data, fast kriging estimations of RMR between borehole sampling locations
at the centroids of the elements of the numerical model, and model validation. For the purpose of an integrated underground
excavation design, a step further is made by incorporating into the 3D mechanical numerical model of the rock mass, the three-dimensional
(3D) solid geological model, thus coupling the geology with the ground (geotechnical) model (i.e. each element of the numerical
model is assigned a geological material). The mechanical properties of each finite difference cell (or Representative Elementary
Volume) of the ground model were then prescribed according to its geological type, the spatial heterogeneity of the rock mass
expressed quantitatively with the kriging model, and the upscaling calculations of the mechanical properties of the intact
rocks determined in the laboratory, based on the size-effect (strength dependence on size) and Damage Theory. Furthermore,
a preliminary numerical simulation of the advance of unsupported tunnels in the model of the heterogeneous rock mass was performed
for illustration purposes. 相似文献
13.
土层工程性质与其沉积环境关系分析研究 总被引：7，自引：4，他引：3
对江苏北部沿海地区与长江三角洲地区土层的工程性质进行分析对比 ,发现这两地区的土层在同一个历史时期所沉积但土层工程性质完全不一样。因此分析了该两地区在同一历史时期的沉积环境与当时的水动力条件与沉积物源的来源。由分析研究结果得到 ,土层的物理力学性质与该土层当时的沉积环境、水动力条件与沉积物源有重要的关系。因此对土层如果能了解其在沉积过程当中的沉积条件 ,更有利于分析研究该土层的物理力学性质 相似文献
14.
Berenice Zapata-Norberto Eric Morales-Casique Graciela S. Herrera 《Hydrogeology Journal》2018,26(3):755-769
Severe land subsidence due to groundwater extraction may occur in multiaquifer systems where highly compressible aquitards are present. The highly compressible nature of the aquitards leads to nonlinear consolidation where the groundwater flow parameters are stress-dependent. The case is further complicated by the heterogeneity of the hydrogeologic and geotechnical properties of the aquitards. The effect of realistic vertical heterogeneity of hydrogeologic and geotechnical parameters on the consolidation of highly compressible aquitards is investigated by means of one-dimensional Monte Carlo numerical simulations where the lower boundary represents the effect of an instant drop in hydraulic head due to groundwater pumping. Two thousand realizations are generated for each of the following parameters: hydraulic conductivity (K), compression index (C c), void ratio (e) and m (an empirical parameter relating hydraulic conductivity and void ratio). The correlation structure, the mean and the variance for each parameter were obtained from a literature review about field studies in the lacustrine sediments of Mexico City. The results indicate that among the parameters considered, random K has the largest effect on the ensemble average behavior of the system when compared to a nonlinear consolidation model with deterministic initial parameters. The deterministic solution underestimates the ensemble average of total settlement when initial K is random. In addition, random K leads to the largest variance (and therefore largest uncertainty) of total settlement, groundwater flux and time to reach steady-state conditions. 相似文献
15.
In recent years, geotechnical engineers are using tyre waste to alter the properties of soil for providing sustainable solutions to complex engineering problems. It is noted that black cotton soil, which is expansive in nature, covers a major portion of the Indian sub-continent, such as the Deccan plateau, Malwa plateau and a portion of Gujarat and poses challenging problems to infrastructural development in the region. In the present study, authors have characterised the geotechnical properties of black cotton soil, which is partially replaced with 4.75 mm passing – 2 mm retained (coarse fraction) and 2.0 mm passing - 75 micron retained (fine fraction) shredded tyre waste. The results of the experimental studies clearly show that partial replacement of black cotton soil with shredded tyre waste alters the geotechnical properties favourable to engineering applications and greatly reduces the swelling potential of the black cotton soil. It is noted that instead of fine fraction (2.0–0.075 mm), replacement with coarse fraction (4.75–2.00 mm) of shredded tyre waste can better be used for light weight fill behind the retaining walls as well as for embankment construction as it helps in reducing swelling pressure as well as improving the strength properties. 相似文献
16.
上海市第四系的工程地质研究 总被引：4，自引：0，他引：4
通过２０余项工程代表性的钻孔岩芯分析,对比了上海市１２０ｍ以浅晚第四纪各沉积层的成因类型,形成时代,岩性及其物理力学性质,并按地基工程要求。编制了“地基土层次名称表”。表中将沉积层划分为１２个工程地质层及众多亚层。在此基础上,参照已有２０００多项工程勘察资料,编制成多时段１：５万古地理图,从而摸清了本区各土层的空间分布规律及其结构变化特征。根据地层结构差异,编制了 桩基工程地质分区图”,阐述了天然地基和三个不同桩基区岩土工程地质条件及应用中需注意的事项,为上海市工程勘察、设计和麓工提供了可靠的科学依据。 相似文献
17.
Mohamed O. Arnous 《Arabian Journal of Geosciences》2013,6(5):1349-1369
With the development of economic activities in the world, the construction activities have also increased. A proper surface and subsurface investigation is made to assess the general suitability of the site and to prepare an adequate and economic safe design for the proposed work. The main purpose of the current study is to create a spatial model of the geotechnical conditions and considerations by using geographic information systems (GIS) techniques to develop and analyze a site model and to plan site activities at the new extension of Suez City (SC). In the geotechnical site evaluations, GIS can be used in four ways, data integration, data visualization and analysis, planning and summarizing site activities, and data presentation. The integrated data can be displayed; manipulated and analyzed using tools build into the GIS programs, thus creating the geotechnical site model of the study area. Decisions can be made for further site activities and the results of the site activities can be integrated into the GIS site model. Interpretation of geotechnical data frequently involves assimilating information from many sites each with a unique geographical location. Interpretation of these data requires the spatial location to incorporate into the analysis. Weights are assigned to different of mechanical, physical soil properties, geological, hydrogeological, and other ancillary data. Finally, the weighted maps are integrated using a GIS based on the construction purposes for the new extension of SC for significant cost savings in design, construction and longevity. The ideal and good zones’ highest regime has been observed towards central and western regions with sporadic pockets. The marginal zones to average zones are moderately suited for shallow foundation. 相似文献
18.
Preparation of a geotechnical microzonation model using Geographical Information Systems based on Multicriteria Decision Analysis 总被引：3，自引：0，他引：3
The purpose of this study is to develop a geotechnical microzonation model using Geographical Information Systems (GIS) based on Multicriteria Decision Analysis (MCDA). As study area, the Eskişehir downtown area has been chosen. Eskişehir is one of the most rapidly growing cities in central Turkey. The model inputs include slope, flood susceptibility, soil, depth to groundwater table, swelling potential, and liquefaction potential. The weight and rank values are assigned to the layers and to the classes of each layer respectively. The assignment of the weight/rank values and the analysis are realized by the application of two different decision models, namely Simple Additive Weighting (SAW) and Analytic Hierarchy Process (AHP) methods. The geotechnical microzonation maps prepared as outputs of these methods are found to be consistent with each other and confirmed by the experts within the study area. The geotechnical microzonation map prepared using the AHP method is recommended as the final map of the study. 相似文献
19.
深海沉积物土工力学特性是深海资源开发设备设计的重要依据。根据现有的深海土工力学原位测量和取样实验的数据,分析沉积物物性参数与贯入阻力的相关关系,建立含水率、湿密度和孔隙比与压力沉陷的关系式。结果表明:研究区深海沉积物以砂质粉砂、黏土质粉砂为主,具有高含水率、大孔隙比、低密度等特征;物理参数与贯入阻力之间有较好的相关关系,其中,含水率、孔隙比、孔隙度与贯入阻力呈反比相关关系;而湿密度与贯入阻力呈正比相关关系;以含水率、湿密度和孔隙比为自变量的多变量回归分析方程能更好地表达沉积物物理特性与贯入阻力的相关关系;基于Bekker沉陷模型,建立接地比压与贯入阻力的关系,能客观反映深海沉积物的沉陷特性与承载特性。 相似文献