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1.
Erzurum, the biggest city of Eastern Anatolia Region in the Turkey, is located in Karasu Plain. Karasu Plain, located on the
central segment of the Erzurum Fault Zone, is an intermountain sedimentary basin with a Miocene-Quaternary volcanic basement,
andesitic-basaltic lava flows and fissure eruptions of basaltic lava. It was filled in the early Quaternary by lacustrine
fan-delta deposits. The basin is characterized by NNE-SSW trending sinistral wrench faults on its eastern margin and ENE-WSW
trending reverse faults on its southern margin. Both systems of active faults intersect very near to Erzurum, which is considered
to be the most likely site for the epicenter of a probable future large earthquake. Historical records of destructive earthquakes,
morphotectonic features formed by paleo-seismic events and instrument seismic data of region indicate to a very high regional
seismicity. The residential areas of Erzurum are located on thick alluvial fan deposits forming under the control of faults
on the central segment of the Erzurum Fault Zone, which is one of the most active fault belts of the East Anatolian Region.
Over time, the housing estates of city such as Yenisehir and Yildizkent have been expanded toward to the west and southwest
part of Erzurum as a consequence of rapid and massive construction during the last 30 years. Geotechnical investigation has
therefore been undertaken the residential areas of city in order to characterize geotechnical properties over the varied lithologies
examine the potential for geotechnical mapping and assess the foundation conditions of the present and future settlement areas.
The geological field observations and operations have been performed to make the soil sampling and characterize the lateral
and vertical changes in thickness of the alluvial deposits in trenches, excavations and deep holes with 6–12 m sections. The
soil samples have been subjected to a series of tests under laboratory conditions to obtain physical and mechanical properties.
Furthermore, the standard penetration tests have been applied to the soils under field conditions. The geological field observations,
geotechnical data and distribution of bearing capacity have been considered for the geotechnical mapping. Based on the geotechnical
map, there are five geotechnical zones distinguished in the study area. 相似文献
2.
Myint Win Bo Ming-Fang Chang A. Arulrajah Victor Choa 《Geotechnical and Geological Engineering》2012,30(1):45-62
Geotechnical ground investigation is important in all construction works particularly, land reclamation projects. The Changi
East reclamation project is a mega project that involves creation of land space as large as 3,000 hectares in multiple phases
between 1991 and 2005. Ground investigation plays a critical role in the Changi project which involved substantial amount
of ground improvement works after reclamation by sand filling. One important aspect of the investigation was to evaluate the
geotechnical characteristics of the underlying compressible soils beneath the original seabed for the selection of suitable
methods of ground improvement. The other important aspect of the investigation was to characterize and verify the compactness
of the reclaimed sand fill. Many types of in situ tests were extensively used in the project. The field vane shear test provides
correlations between the undrained shear strength and depth for the upper and the lower marine clay strata in the Northern
part and the Southern Part of the reclaimed site. Combined with laboratory undrained shear strength tests, the field vane
strength profiles allow the derivation of the undrained shear strength over effective stress ratios for the upper and the
lower marine clays. In addition, results from three other in situ tests, the piezocone cone penetration test, the flat dilatometer
test, and the self boring pressuremeter test provided useful verification of these correlations. A field-performance based
method of assessing degree of consolidation in the underlying clay was developed by combining field monitoring, laboratory
testing and conventional as well as specialized in situ testing. An effective use of in situ testing methods for assessment,
the outcome of ground improvement and for fill quality control in the densification of granular soils is illustrated with
field observation data collected at the project site. 相似文献
3.
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
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5.
Field tests are widely used for soil characterization in geotechnical applications in spite of implementation difficulties. The light penetrometer is a well-known testing tool for fine soils, but the physical interpretation of the output data in the case of coarse granular materials is far less evident. Indeed, the data are considerably more sensitive in this case to various parameters such as fabric structure, particle shapes or the applied impact energy. In order to achieve a better understanding of the penetration process into a coarse granular material, a numerical study was performed by means of contact dynamics simulations. The penetration of a moving tip in a sample composed of irregular grain shapes was studied and the influence of the driving velocity and input energy on the penetration strength was analyzed. The results show that the latter grows with both the penetration rate and energy, despite the strong fluctuations occur due to a jamming–unjamming process in which the contact network connectivity evolves intermittently in correlation with the penetration strength. This analysis suggests that the time-averaged data provided by a penetrometer is reliable information from which the bulk strength properties of coarse granular materials can be evaluated. 相似文献
6.
Iman Hosseinpour Marcio S. S. Almeida Mario Riccio Magnos Baroni 《Geotechnical and Geological Engineering》2017,35(3):1051-1066
The compressibility properties, undrained shear strength, and stress history are essential for reliable calculations of settlement and bearing capacity of soft soils. However, it is sometimes a challenge to determine representative parameters for very soft and high plasticity clays, which are often found in Brazilian coastal areas. In this study an extensive site investigation was planned aiming to interpret the behaviour of a trial embankment on stabilized soft ground. The site investigation was carried out in a test area located in the west of city of Rio de Janeiro, consisted of three clusters in which standard penetration tests, vane shear tests, and piezocone tests (CPTu) were performed. A number of correlations was developed and compared with empirical equations in order to verify their reliability. The results of these tests made it possible to define geotechnical parameters of the soft clay to use in the numerical and analytical computations of the embankment on reinforced ground. 相似文献
7.
D. Ramakrishnan 《Natural Hazards》2014,70(1):485-499
Kachchh region of India is a rift basin filled with sediments from Jurassic to Quaternary ages. This area is tectonically active and witnessed several major earthquakes since the recent historical past. During an earthquake event, the water-laden foundation soil liquefies and causes damage to buildings and other civil engineering structures. The January 26, 2001, Bhuj earthquake demonstrated extensive liquefaction-related damages in entire Kachchh Peninsula. Therefore, evaluation of liquefaction susceptibility of unconsolidated sediments is a vital requirement for developing seismic microzonation maps. In this paper, a new approach involving remote sensing techniques and geotechnical procedures is demonstrated for effective mapping of liquefaction-susceptible areas. The present and paleo-alluvial areas representing unconsolidated sediments were mapped using Landsat-TM data and field reflectance spectra. Spectral discrimination of alluvial area was made using the feature-oriented principal component selection and spectral angle mapping techniques. Subsequently, field geotechnical investigations were carried out in these areas. It is evident from the results that the alluvial soils are predominantly sandy loam with very low (7–28) standard penetration test values. The evaluated factor of safety for these soils varies from 0.43 to 1.7 for a peak ground acceleration of 0.38. Finally, a liquefaction susceptibility map is prepared by integrating results on alluvium distribution, factor of safety, and depth to water table. 相似文献
8.
Guidance is provided for geotechnical engineers designing civil engineering works in silty soils based on a detailed characterisation of a glaciomarine silt from Os in western Norway. It was found that these soils are susceptible to disturbance by good quality fixed piston tube sampling and care needs to be taken when using laboratory derived design parameters, particularly for consolidation and shear strength properties. A technique for assessing sample disturbance using shear wave velocity and suction measurements proved promising. Conventional techniques for determining soil strength from triaxial tests in silt are inappropriate due to the dilational nature of the material and more reliable and logical strength estimates can be made from a limiting strain criterion. Field vane data should be used with caution as measured strength, particularly remoulded values, may be high and it seems more reliable parameters can be derived from CPTU tests. One dimensional consolidation and creep of these silts can be modelled successfully by the well-known Janbu formulation. The behaviour of the Os silts does not fit easily into classical soil mechanics and published frameworks for soft soils. It seems the material is of “transitional” type and this work adds to the database of such soils which includes other natural silts and gap graded soils. For future work it is recommended that larger sample tubes (say 75 mm) with a very sharp cutting edge should be used in parallel with in situ CPTU testing. 相似文献
9.
Determination of the in situ engineering properties of foundation materials has always been a challenge for geotechnical engineers and, thus, several methods have been developed so far. Dynamic Cone Penetration (DCP) test is one of the most versatile amongst them. In the present research, a light weight simple DCP device was developed and used for evaluation of the engineering properties of sandy soils in laboratory conditions. The device consisted of an 8-kg hammer that drops over a height of 575 mm, and drives a 60° cone tip with 20 mm base diameter into the ground. To control the validation of the results, laboratory direct shear and plate load tests were used as reference tests. The soil sample was a poorly graded sandy soil (SP) taken from alluvial deposits of the Tehran plain. All DCP tests and PLTs were undertaken on compacted soil in a mould with 700 mm diameter and 700 mm height. Based on the results of the experiments, the relationships between Dynamic Penetration Index (DPI), relative density (Dr), modulus of elasticity (E), shear modulus (G), modulus of subgrade reaction (KS), and the friction angle of the soil were obtained with a high coefficient of determination (> 90%). The repeatability of the test results was also evaluated by calculating the coefficient of variations (Cv), which was less than 30% for all tests. 相似文献
10.
11.
《Geomechanics and Geoengineering》2013,8(4):265-281
This paper presents a re-appreciation of the ground characterisation and the criteria to select the most representative geomechanical parameters to consider in a numerical model to predict the behaviour of a retaining wall of a deep excavation in highly weathered granite rock masses and residual soils. This study was focused in the construction of a deep station of Metro do Porto, which involved a cut and cover solution, with unusual proportions (in plant and in depth), built in the typical Oporto's granite weathered profiles, being the excavation conducted with retaining walls consisting of multi-anchored concrete piles. Specific sections were carefully instrumented, due to the presence of historic buildings in the vicinity. The definition of representative model parameters was based on precise laboratory tests over high quality soil samples, including oedometer and high-precision triaxial tests. Geotechnical and geological characterisation of all the area for the original design, was initially based on in situ tests, such as SPT and rock masses classification, and on the local experience on this type of ground. After this construction, the assumptions of parameterisation, using a constitutive modelling based on new laboratory tests over high quality block samples, allowed a reanalysis of the assumptions on the design phase. A back-analysis of monitored displacements and forces during the construction was made, assuming the designed structural solutions, which were in fact implemented in construction, but considering the new approaches on the definition of the geomechanical parameters for the prevailing weathered rock masses, necessary for the numerical simulation based on the commercial software Plaxis®, using the Mohr-Coulomb and “Hardening-Soil” models. Some specific changes of the constructive sequence during the excavation and activation of supporting system were attained, by looking at the information found during the construction. The results of this parametrical re-approach and analysis of the singularities of highly weathered granite and corresponding residual soils masses for modelling of retaining walls of large excavations are discussed. 相似文献
12.
浊水溪冲积扇是台湾水资源最为丰富但也是地面沉降最严重地区。近年来该区域的地面沉降因有可能威胁高铁行车安全而备受关注。本文整合历年累积的地下水位及地面沉降等相关监测数据,验证了地下水位变化与含水层补给之机制,探讨了地下水周期性波降条件下土层压缩特性以及高铁路堤与桩基础工程结构的沉降行为。认为对于设置桩基础的线型高架结构而言,区域性地下水位波降不致增加桥墩间的差异沉降,但桩基础若承受邻近局部的额外载重,则可能伴随地下水位波降产生持续性的差异沉降,其长期效应将对线型交通结构物的平整度及安全性造成负面影响。 相似文献
13.
14.
A magnitude 7 earthquake occurred in southwest Mozambique in February 2006, triggering extensive liquefaction around the fault rupture. Samples were recovered from the liquefied soils for laboratory testing to calibrate a numerical model for the assessment of liquefaction susceptibility. Laboratory tests and simulations confirm that the alluvial sands from the area affected by the earthquake have a very high susceptibility to liquefaction, although this depends strongly on the in situ density, which is likely to be low since the soils are deposited in a major flood plain. Since many areas of Mozambique, including parts of the major coastal cities, are on similarly loose and saturated deposits, there could be a significant liquefaction hazard in future earthquakes. 相似文献
15.
Investigation of solid waste soil as road construction material 总被引:1,自引:0,他引:1
The geotechnical properties of solid waste soils for use as sub-base materials in road construction were investigated. A series of field tests and laboratory tests were performed to assess the physical and mechanical properties of the solid waste soils sampled from a landfill site, near to a riverside, which had been reclaimed over the last two decades. The tests showed that geotechnical properties are clearly affected by the magnitude of organic matter content. As the organic matter content increases, the maximum dry unit weight, the shear strength and bearing capacity of ground decrease, while the void ratio and compressibility increase. If the organic matter content is more than about 8% in solid waste soils, it is not suitable for use as a sub-base material in road construction due to the significant decrease of shear strength and bearing capacity. 相似文献
16.
Effects of crude oil contamination on geotechnical properties of clayey and sandy soils 总被引:6,自引:0,他引:6
The southern coastal plain of Iran at the Persian Gulf encounters oil pollution due to the historical oil exploitation, related tanker navigations and accidents, and petrochemical industrial expansions in the recent years. Therefore, it is important to investigate the geochemical properties of oil-contaminated coastal soils and sediments for engineering and environmental purposes. Here, an extensive laboratory testing program was carried out to determine the effects of crude oil contamination on some of the geotechnical properties of clayey and sandy soils such as CL, SM and SP sampled from the coastal soils from this area. The testing included basic properties, Atterberg limits, compaction, direct shear, uniaxial compression and permeability tests on clean and contaminated soil samples at the same densities. The contaminated samples were prepared by mixing the soils with crude oil in the amount of 2%, 4%, 8%, 12%, and 16% by dry weight. The results indicated a decrease in strength, permeability, maximum dry density, optimum water content and Atterberg limits. Knowledge of these effects of oil contamination is important in coastal engineering and environmental remediation activities of the studied coastal plain. 相似文献
17.
流域上游基岩与下游冲积平原土壤化学组成的对比 总被引:2,自引:0,他引:2
对海河水系流域、鄱阳湖水系流域上游的基岩与下游的冲积平原土壤之间化学组成的对比研究显示,下游冲积物土壤的化学组成明显地受源岩成分、形成过程和形成环境的影响。流域上游基岩的一些特征元素在冲积物土壤中被明显地继承,如海河流域基岩和土壤中的CO2、CaO、MgO、FeO、Sr,鄱阳湖流域基岩和土壤中的W、Sn、Bi、U、Th、Pb、Rb、Tl、As、Sb、Se、Hg、Nb、Ta、Hf、B、Be、Ge、Pt、Pd、Y。受形成过程和形成环境的影响,处于暖温带半湿润季风气候下的海河流域冲积平原土壤以极富集CO2、CaO、Na2O、Cl,显著富集MgO、FeO、Sr,富集P、S为特征;而处于亚热带湿润季风气候下的鄱阳湖流域冲积平原土壤则以显著富集Hg、Se和富集Al2O3、Fe2O3H2O^+、W、Sn、Bi、Mo、U、Th、Pb、Rb、Cs、Tl、Li、Be、B、Ga、Ge、Nb、Ta、Zr、Hf、As、Sb、Co、Cr、Ti、V、Zn、Pt、Pd、REE、Y为特征。无论是海河流域还是鄱阳湖流域的冲积平原土壤,均富集As、Sb、Hg、B、Cl、W、Sn、Bi、Pb、Se、Ge、Li、Cs、Cu、Au、Fe2O3、V、Cr、Ni、Zr、Hf、Y。 相似文献
18.
The main objective of this study is to assess the land degradation risk of cultivated land in El Fayoum depression. The physiographic map of the depression was produced by using remote sensing and land surveying data. The depression comprises lacustrine plain, alluvial–lacustrine plain, and alluvial plain representing 12.22%, 53.58%, and 34.20% of the total area, respectively. The soil, climate, and topographic characteristics of the depression were extracted from land surveying, laboratory analyses, digital elevation model, and available reports. A simple model was designed to employ these data for assessing the chemical and physical risk of land degradation using Arc-GIS 9.2 software. The obtained results indicate that severe risk to chemical and physical degradation affect 54.15% and 29.23% of the depression, respectively. The current status of soil salinity, sodicity, and water table indicate that most of lacustrine and alluvial–lacustrine soils are actually degraded by salinization, sodification, and waterlogging. The results of degradation risk and the actual hazard indicate that the human activities are not sufficient to overcome the degradation processes in the most of the depression (80. 22%). Moreover, a negative human impact affects 26.29% of the area mostly in the alluvial plain. Great efforts related to the land management are required to achieve the agriculture sustainability. 相似文献
19.
A 132 kVA electrical transmission line has been proposed to connect the towns of Eket and Ikot Abasi in the eastern Niger
delta in Nigeria. A geotechnical and hydrological study was performed to geotechnically characterize the route alignment and
to provide data for design of the foundations for the transmission towers. In this paper, we introduce the study location
and its geological, topographical and physiological characteristics, present the hydrological and geotechnical investigations
and their results, and make recomendations for the design of the transmission tower foundations. Hydrological inspection of
the power line alignment revealed that the route is traversed by numerous tributaries of the Qua-Iboe and Imo Rivers, the
two major rivers that control the drainage of the study area. In-situ geotechnical tests consisted of cone penetration tests
(CPTs), vane shear tests, test pit sampling (0–2.0 m depth) and lithologic boreholes (20 and 50 m deep). Laboratory tests
included grain size analysis, pH determination and Atterberg Limits. Based on the CPT log pattern, no of stratum, and refusal
depths, the soils along the transmission alignment were classified into twelve structural domains having common geotechnical
properties. Because of the elevated water levels, and the nature of the soils, deep pile foundations were recommended for
the towers. Software from the Louisiana Transportation Research Center, was employed to estimate skin friction, end bearing,
and ultimate bearing capacities for assumed 225 mm square shaped reinforced concrete pile in each of the different zones of
the alignment. 相似文献