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1.
The Kocaeli earthquake (M w = 7.4) of 17 August 1999 occurred in the Eastern Marmara Region of Turkey along the North Anadolu Fault and resulted in a very serious loss of life and property. One of the most important geotechnical issues of this event was the permanent ground deformations because of both liquefaction and faulting. These deformations occurred particularly along the southern shores of ?zmit Bay and Sapanca Lake between the cities of Yalova and Adapazar? in the west and east, respectively. In this study, three sites founded on delta fans, namely De?irmendere Nose, Yeniköy tea garden at Seymen on the coast of ?zmit Bay, and Vak?f Hotel site on the coast of Sapanca Lake were selected as typical cases. The main causes of the ground deformations at these sites were then investigated. Geotechnical characterization of the ground, derivation of displacement vectors from the pre- and post-earthquake aerial photographs, liquefaction assessments based on field performance data, and analyses carried out using the sliding body method have been fundamental in this study. The displacement vectors determined from photogrammetric evaluations conducted at De?irmendere and Seymen showed a combined movement of faulting and liquefaction. But except the movements in the close vicinity of shorelines, the dominant factor in this movement was faulting. The results obtained from the analyses suggested that the ground failure at De?irmendere was a submarine landslide mainly because of earthquake shaking rather than liquefaction. On the other hand, the ground failures at the Yeniköy tea garden on the coast of Seymen and the hotel area in Sapanca town resulted from liquefaction-induced lateral spreading. It was also obtained that the ground deformations estimated from the sliding body method were quite close to those measured by aerial photogrammetry technique. 相似文献
2.
1998 Adana-Ceyhan (Turkey) Earthquake and a Preliminary Microzonation Based on Liquefaction Potential for Ceyhan Town 总被引：1，自引：0，他引：1
A moderate earthquake (Ms = 6.2) occurred in the Cukurova region in the southern part of Turkey, on 27 June 1998. It resulted in loss of 145 lives and significant damage particularly in the settlements close to the epicenter at the south of Ceyhan town. Widespread liquefaction and associated sand boils, ground fissures and ground deformations due to lateral spreading occurred during this earthquake. In this study, main characteristics of the earthquake are presented and liquefaction throughout the site was assessed. An attempt was also made to establish preliminary microzonation maps for Ceyhan using the data from liquefaction susceptibility analyses. The results of the analyses indicated that the data from the liquefied sites were within the empirical bounds suggested by the field-performance evaluation method. Fortunately, most of the riversides were used for agricultural purposes alone, damage to structures from liquefaction and associated ground failures were rather limited. Preliminary assessments indicated that at depths of about 5 m the liquefaction potential of thin sand layers tends to diminish. 相似文献
3.
One of the major causes of earthquake damage is liquefaction. However, it doesn't result in severe harm unless it leads to ground surface damage or ground failure. Therefore, prediction of potential for ground surface damage due to liquefaction is one of the important issues in microzonation studies for liquefaction-induced damage in areas with high seismicity. In 1985, based on a database compiled from Chinese and Japanese earthquakes, Ishihara considered the influence of the non-liquefied cap soil on the occurrence or non-occurrence of ground failure (mainly sand boiling), and proposed an empirical approach to predict the potential for ground surface damage at sites susceptible to liquefaction. However, some investigators indicated that this approach is not generally valid for sites susceptible to lateral spread or ground oscillation. In this study, a contribution to improve the approach by Ishihara is made. For the purpose, an index called liquefaction severity index (LSI) and data from two devastating earthquakes, which occurred in Turkey and Taiwan in 1999, were employed. The data from liquefied and non-liquefied sites were grouped and then analysed. Based on the observations reported by reconnaissance teams who visited both earthquake sites and the results of the liquefaction potential analyses using the filed-performance data, a chart to assess the potential for ground surface disruption at liquefaction-prone areas was produced. The analyses suggest that the procedure proposed by Ishihara is quite effective particularly for the occurrence of sand boils, while the bounds suggested in this method generally may not be valid for the prediction of liquefaction-induced ground surface disruption at sites susceptible to lateral spreading. The chart proposed in this study shows an improvement over the Ishihara's approach for predicting the liquefaction-induced ground surface damage. The microzonation maps comparing the liquefaction sites observed along the southern shore of Izmit Bay and in Yuanlin, and the surface damage and non-damage zones predicted from the proposed chart can identify accurately the liquefaction (sand boiling and lateral spreading) and no-liquefaction sites. 相似文献
4.
On June 27, 1998, a moderate earthquake measuring 5.9 on the Richter scale struck the alluvial plains of Cukurova in the Adana-Ceyhan region of Turkey. The earthquake resulted in 145 deaths, about a thousand injuries and significant damage to more than ten thousand structures. The coincidence of the projected location of the release of energy along the earthquake fault with a very vulnerable geological surface formation (the thick alluvial deposits of Ceyhan River containing loose sand layers) resulted in liquefied sediments of substantial thickness and extensive areal distribution. Liquefaction associated ground deformations such as lateral spreading, flow failures, ground fissures and subsidence, sand boils, and slope failures were observed. This paper presents and analyses the geotechnical aspects of this earthquake with the main emphasis on the observed liquefaction and associated ground deformations, together with the earthquake characteristics. The observed liquefaction mechanisms provide valuable information on the seismic response of the alluvial soils covering most of the Cukurova plains, an area of industrial and agricultural importance with more than 2 million inhabitants. The observations from this earthquake also provide us with an opportunity to further improve our understanding of the observed phenomena and their effects that can be expected during other future earthquake events around the world. 相似文献
5.
Aurelian Catalin Trandafir Kyoji Sassa 《Geotechnical and Geological Engineering》2006,24(6):1627-1639
This paper outlines a methodology for evaluating the likelihood of catastrophic landslide occurrence on gentle slopes in liquefiable
soils during earthquake. The approach is based on a modified Newmark sliding block model of assessing the earthquake-induced
undrained landslide displacements for conditions of no shear stress reversals on the sliding surface. By employing the shear
resistance-displacement relationship from undrained monotonic ring shear tests, the simulation model incorporates the sensitivity
of computed displacements to variations in yield acceleration. The proposed approach involves an examination of undrained
seismic slope performance under various horizontal seismic waveforms scaled to different specific values of the peak earthquake
acceleration. An example problem illustrates how the proposed methodology may be used to demarcate, based on the magnitude
of permanent seismic displacement, the levels of low, moderate and high risk of catastrophic landslide on a gentle slope in
a saturated cohesionless soil susceptible to liquefaction during earthquake. 相似文献
6.
Multilinear Regression Analysis for Seismic Response and Engineering Properties of Liquefiable Coromandel Coastal Soil Deposits 总被引：1，自引：0，他引：1
S. Senthamilkumar C. Natarajan K. Muthukumaran 《Geotechnical and Geological Engineering》2009,27(3):439-453
This paper investigates the seismic characteristics and geotechnical properties with respect to the liquefaction potential
of the deposits in the Coromandel coastal line of Nagapattinam town, Tamilnadu, India. A series of field tests were conducted
using standard penetration test, cone penetration test and plate load test. Laboratory tests were conducted on the collected
samples. From the results, a microzonation map was developed for the liquefaction potential and settlements. Some multilinear
regression models between permeability, fines content, relative density, coefficient of curvature, coefficient of uniformity,
mean particle size, factor of safety, settlement, standard penetration test values and cone penetration test values were developed.
The shear wave velocity and shear modulus were calculated from the field penetration tests and correlations between the normalized
values of peak ground accelerations, velocities and displacements, which were obtained from the equivalent linear ground motion
analysis using SHAKE software, with other parameters of soil. From the results, it was found that at some of the areas are
vulnerable to high amplification of waves even for small earthquake. 相似文献
7.
土工结构地震滑动位移统计分析 总被引：1，自引：0，他引：1
土工结构在地震荷载下的滑动位移是评估结构安全性能的重要参数。采用一种新型的地震波选择方法,在强震数据库中选择修改地震波,以有效地在结构动力分析中引入不同特征地震波的影响。通过一个简单的土工结构地震滑移模型,系统地分析了结构基本周期和滑动面屈服系数对地震滑移概率及相应滑移距离的影响,并提出了滑动体在不同地震场景和基本周期条件下的滑移概率和累积滑动位移的统计模型,对基于性能的土工结构抗震设计具有重要的参考意义。 相似文献
8.
9.
Farshid Vahedifard Christopher L. Meehan 《Geotechnical and Geological Engineering》2011,29(6):1023-1034
Predictive displacement-based methods provide a useful index of the seismic performance of earth dams and embankments and
can be used in preliminary assessments of these structures. In practice, simplified Newmark-type sliding block methods are
commonly used for this purpose. Using a database of 122 previously published case histories of permanent deformations of earth
dams and embankments, the performance of six simplified sliding block models was examined. The results show that all six simplified
methods underpredict seismic displacement for many of the embankment and earth dam cases that were examined, sometimes by
a significant amount. An empirical correlation was developed by performing linear multiple regression analysis utilizing multiple
slope and ground motion input parameters. This approach is believed to more properly reflect strong ground motion characteristics
than the use of a single ground motion parameter such as the peak ground acceleration, the approach that has been previously
employed in other correlations of this type. After exploring numerous functional forms, the final resulting seismic displacement
correlation that was proposed was determined to be a function of the critical acceleration, the critical acceleration ratio,
the slope height, the peak ground acceleration, the peak ground velocity, the spectral acceleration, and the predominant period
of earthquake shaking. The proposed empirical equation yields better correlation with the case history database than does
other existing empirical correlations or simplified sliding block models. 相似文献
10.
V. K. Gahalaut P. K. Gupta R. Chander V. K. Gaur 《Journal of Earth System Science》1994,103(3):401-411
We estimate the distribution of slip in the dip section of the causative fault for the 1905 Kangra earthquake by applying
the minimum norm inversion technique to differences in pre- and post-earthquake levelling data collected along the Saharanpur-Dehradun-Mussoorie
highway. For this purpose it is assumed that the causative fault of the 1905 Kangra earthquake was planar with a dip of 5°
in the northeast direction and that it had a depth of 6 km at the southern limit of the Outer Himalaya in Dehradun region.
The reliably estimated maximum slip on the fault is 7.5 m under the local northern limit of the Outer Himalaya. Using the
inverted slip distribution we estimate that the maximum permanent horizontal and vertical displacements at the surface due
to the Kangra earthquake were about 4 m and 1.5m respectively. The maximum transient displacements at the surface should have
exceeded these permanent displacements. These estimates of maximum slip on the causative fault and the resultant maximum permanent
and transient displacements at the surface during the Kangra earthquake may be taken tentatively as being representative of
the great Himalayan earthquakes. 相似文献
11.
2016年11月25日新疆阿克陶县木吉乡发生MS6.7地震,发震构造为公格尔山拉张系北端的木吉断裂,断裂总长度超过100 km,以右旋走滑为主兼有一定的拉张分量。文章在对震区进行了初步的地震地质灾害调查,总结砂土液化和地裂缝在高原季节性冻土地区的分布及发育特点的基础上,发现:1)在研究区Ⅰ维日麻村的砂土液化主要沿原有泉眼或沿地裂缝发育,沿泉眼形成的砂土液化其喷砂锥的覆盖面积达36.1 m2,占总液化面积的60%,研究区Ⅱ布拉克村的砂土液化则主要是沿草甸的根系喷出,在地表形成大面积的最新涌水结冻特征;2)对研究区Ⅱ布拉克村地裂缝的深度进行统计,反演出区域冻土层厚度,结合探槽揭露的地层剖面,推断冻土层发生大面积地裂缝是因为地震引起冻土层下部融土层发生砂土液化导致土层变形失稳,从而使冻土层发生形变产生一系列规律性的地裂缝。 相似文献
12.
The Niumiangou landslide (~7.5 × 106 m3) was the largest that occurred in the town of Yingxiu (the epicentral area) during the 2008 Wenchuan earthquake. This landslide originated on a steep slope (~30°) that was located directly above the rupture surface of the responsible fault and then traveled ~2 km after flowing down the axes of two gently sloping (<12°) valleys. Evidence at the site indicates that the landslide materials were highly fluidized and underwent rapid movement. To examine the initiation and movement mechanisms of this landslide, we performed a detailed field survey, conducted laboratory tests on samples taken from the field, and analyzed the seismic motion. We conclude that the landside materials were displaced due to seismic loading during the earthquake and that liquefaction may have been triggered in saturated layers above the sliding surface with progressive downslope sliding, which resulted in the high mobility of the displaced materials. The liquefaction of colluvial deposits along the travel path due to loading by the sliding mass enhanced the mobility of the displaced mass originating in the source area. Using an energy-based approach, we estimated the dissipated energy in our cyclic loading test and the possible energy dissipated to the soil layer on the slope by the earthquake. We infer that the seismic energy available for the initiation of the slope failure in the source area may have greatly exceeded the amount required for the initiation of the liquefaction failure. The slope instability might have been triggered several seconds after the arrival of seismic motion. 相似文献
13.
海底缓坡场地地震侧移数值分析方法 总被引：2，自引：0，他引：2
地震动使海底倾斜土层软化、液化并产生永久变形和位移。基于有限元理论,提出一种海底缓坡场地地震引起水平侧移的数值计算方法,将波浪荷载简化为恒定压力荷载和初始孔压,采用二维有效应力动力有限元分析方法进行液化分析,同时由模量软化理论得到土层在地震动各时段的模量,通过非线性静力方法计算软化、液化引起的水平侧移。由算例分析了土层坡度、液化层及上覆非液化层厚度、波浪荷载等因素对侧移的影响,通过对比分析表明了该方法的有效性,可为近海工程场地地震地质灾害评价提供参考数据。 相似文献
14.
The town of Edessa is located on Northern Greece at a region that is characterized as low seismicity zone due to the fact
that few moderate events of M < 6 occurred during the last century. According to the Greek Seismic Code, the expected acceleration having a 10% probability
of being exceeded in 50 years is equal to 0.16g. However, an amplification of ground motion is likely to occur due the local geology that is consisted of Holocene fluvio-torrential
deposits. The basic aim of this paper is to evaluate the site amplification due to geological conditions and to assess the
liquefaction hazard. In order to achieve this, 1-D site response analyses were performed. The data that were employed for
the construction of the numerical models have been collected from borings with standard penetrations tests (SPT) that were
drilled for construction purposes. Afterward, the liquefaction potential of the subsoil layers was evaluated taking into consideration
two seismic scenarios. The first scenario was based on the seismic parameters, earthquake magnitude and PGA, assigned by the
Greek Seismic Code. On the second seismic model, we employed the values of acceleration, resulted from the 1-D analyses and
the earthquake magnitude as it was defined by the Greek Seismic Code. In order to compile the liquefaction hazard maps, we
initially estimated the liquefaction potential index (LPI) of the soil columns using the parameters provided by SPT, for both
seismic loadings, and afterward we correlated these values with the proposed classification of the severity of liquefaction-induced
deformations. In addition, having computed the value of probability based on the LPI, liquefaction manifestations probability
maps were compiled for both scenarios. The result of this study was that liquefaction-induced ground disruptions are likely
to occur at the center of the city, among the branches of Voda River, only when the amplified values of acceleration are taken
into account to the computation of liquefaction potential. 相似文献
15.
A failed slope may not necessarily require a remedial treatment if it can be shown with confidence that the maximum movement
of the slide mass will be within tolerable limits, i.e., not cause loss of life or property. A permanent displacement analysis
of a landslide for static and seismic conditions is presented using a continuum mechanics approach. Computed values of displacement
for static conditions compare favorably with field measurements and computed values of seismic displacements for a postulated
earthquake motion appear reasonable. Also, the seismic displacements using the continuum mechanics approach compare favorably
with those obtained using the Newmark sliding block procedure for assessing seismically-induced slope deformations. 相似文献
16.
Aurelian Catalin Trandafir Toshitaka Kamai Roy Carl Sidle Mihail Popescu 《Geotechnical and Geological Engineering》2007,25(6):679-691
Failure of several gravity retaining walls in residential areas built on reclaimed land, during the October 23, 2004 Chuetsu
earthquake in Niigata Prefecture, Japan, determined the authorities to consider the seismic retrofit of the walls in order
to mitigate future similar disasters in the urban environment. This study addresses the effectiveness of ground anchors in
improving the seismic performance of such retaining structures through a sliding block analysis of the seismic response of
an anchored gravity retaining wall supporting a dry homogeneous fill slope subject to horizontal ground shaking. Sliding failure
along the base of the wall and translational failure along a planar slip surface of the active wedge within the fill material
behind the wall were considered in the formulation, whereas the anchor load was taken as a line load acting on the face of
the gravity retaining wall. The effects of magnitude and orientation of anchor load on the yield acceleration of the wall-backfill
system and seismically induced wall displacements were examined. It was found that for the same anchor orientation, the yield
acceleration increases in a quasi-linear manner with increasing the anchor load, whereas an anchor load of a given magnitude
acting at various orientations produces essentially identical yield accelerations. On the other hand, the computed earthquake-induced
permanent displacements of the anchored gravity retaining wall decrease exponentially with increasing magnitude of anchor
load. Additionally, the influence of backfill strength properties (e.g., internal friction angle) on the seismic wall displacement
appears to diminish considerably for the anchored gravity retaining wall. A dynamic displacement analysis conducted for the
anchored gravity retaining wall subjected to various seismic waveforms scaled to the same peak earthquake acceleration revealed
a good correlation between the calculated permanent wall displacements and the Arias intensity parameter characterizing the
input accelerogram. 相似文献
17.
Markus J. Schwab Petra Werner Peter Dulski Edward McGee Norbert R. Nowaczyk Sébastien Bertrand Suzanne A.G. Leroy 《Quaternary Science Reviews》2009,28(11-12):991-1005
Lake Sapanca is located on a strand of the Northern Anatolian Fault Zone (NAFZ, Turkey), where a series of strong earthquakes (Ms >6.0) have occurred over the past hundred years. Identifying prehistoric earthquakes in and around Lake Sapanca is key to a better understanding of plate movements along the NAFZ. This study contributes to the development of palaeolimnological tools to identify past earthquakes in Lake Sapanca. To this end several promising proxies were investigated, specifically lithology, magnetic susceptibility, grain size (thin-section and laser analysis), geochemistry, pollen concentration, diatom assemblages, 137Cs and 210Pb. Sedimentological indicators provided evidence for reworked, turbidite-like or homogeneous facies (event layers) in several short cores (<45 cm). Other indicators of sediment input and the historical chronicles available for the area suggest that three of these event layers likely originated from the AD 1957, 1967 and 1999 earthquakes. Recent changes in sediment deposition and nutrient levels have also been identified, but are probably not related to earthquakes. This study demonstrates that a combination of indicators can be used to recognize earthquake-related event layers in cores that encompass a longer period of time. 相似文献
18.
小坡度海底土层地震液化诱发滑移分析方法 总被引：1，自引：0，他引：1
地震可使海底砂质、粉质土层液化并导致上部土层的滑移。基于有效应力有限元动力分析方法和Newmark刚性滑块理论,提出了一种计算海底小坡度（≤5o）土层地震液化引起侧向滑移的简化方法。该方法将波浪荷载简化为海底恒定的上覆压力和初始孔压,忽略了海水粘性对海底土层地震反应的影响,利用改进的Seed孔压模型进行动力分析和液化判别,用Newmark滑块理论计算了土层侧向滑移。通过算例和对比分析,研究了海水深度和土层坡度对侧向滑移的影响,表明该方法的有效性,可为近海工程场地地震地质灾害评价提供参考数据。 相似文献
19.
2008年汶川Mw7.9地震的强地面震动在龙门山前地区造成大量的砂土液化、喷砂冒水等地震灾害现象。震后野外调查发现,砂土液化点主要分布于地下水位只有几米深的山前河流的低阶地处,以大面积砾性土液化为特征,约58%的液化点位于距北川断层20~35km的范围内。对喷水高度及喷水过程进行了详细记录,喷水高度与峰值加速度并没有明显的相关性,喷水高度异常点(2m)集中于山前断裂系统近地表投影处。汶川地震中喷水高度异常、砾性土液化的位置与山前断裂系统的吻合性说明,沉积盆地内的地质构造可能在砂土液化强度和与震动相关的地震灾害方面起到促进作用,所以在类似的地质和水文环境中,除主震的断层错动外,应考虑地质构造在地震危险性评估和建筑物抗震设计中的重要作用。 相似文献
20.
地震液化条件下地面的大变形三维数值分析 总被引：3，自引：1，他引：2
地基液化条件下地面大变形是造成工程结构破坏的主要原因之一。考虑地形、地震、土层、地下水等影响因素,针对典型的岸坡场地3层土地基模型,利用有限差分法FLAC3D,对可液化场地在地震作用下发生地面大变形的过程进行了数值模拟。结果表明,临空面坡比愈大、地表坡度越陡,地基液化地表侧向位移值愈大;变坡度的场地在地震作用下发生的侧移要比单一倾斜率的场地大;地震最大加速度越大、地震持续时间越长,地基液化侧向位移、地表沉陷和隆起现象越严重;液化层的埋深、厚度以及地下水位都对地面大变形的产生有着不同程度的影响,应选择合理的地基处理方案进行处理。 相似文献