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1.
Behaviour of deep immersed tunnel under combined normal fault rupture deformation and subsequent seismic shaking 总被引:1,自引:0,他引:1
Ioannis Anastasopoulos Nikos Gerolymos Vasileios Drosos Takis Georgarakos Rallis Kourkoulis George Gazetas 《Bulletin of Earthquake Engineering》2008,6(2):213-239
Immersed tunnels are particularly sensitive to tensile and compressive deformations such as those imposed by a normal seismogenic
fault rupturing underneath, and those generated by the dynamic response due to seismic waves. The paper investigates the response
of a future 70 m deep immersed tunnel to the consecutive action of a major normal fault rupturing in an earthquake occurring
in the basement rock underneath the tunnel, and a subsequent strong excitation from a different large-magnitude seismic event
that may occur years later. Non-linear finite elements model the quasi-static fault rupture propagation through the thick
soil deposit overlying the bedrock and the ensuing interaction of the rupture with the immersed tunnel. It is shown that despite
imposed bedrock offset of 2 m, net tension or excessive compression between tunnel segments could be avoided with a suitable
design of the joint gaskets. Then, the already deformed (“injured”) structure is subjected to strong asynchronous seismic
shaking. The thick-walled tunnel is modelled as a 3-D massive flexural beam connected to the soil through properly-calibrated
nonlinear interaction springs and dashpots, the supports of which are subjected to the free-field acceleration time histories.
The latter, obtained with 1-D wave propagation analysis, are then modified to account for wave passage effects. The joints between tunnel segments are modeled with special non-linear hyper-elastic elements, properly accounting
for their 7-bar longitudinal hydrostatic pre-stressing. Sliding is captured with special gap elements. The effect of segment
length and joint properties is explored parametrically. A fascinating conclusion emerges in all analysed cases for the joints
between segments that were differentially deformed after the quasi-static fault rupture: upon subsequent very strong seismic
shaking, overstressed joints de-compress and understressed joints re-compress—a “healing” process that leads to a more uniform
deformation profile along the tunnel. This is particularly beneficial for the precariously de-compressed joint gaskets. Hence,
the safety of the immersed tunnel improves with “subsequent” strong seismic shaking! 相似文献
2.
Current tectonic deformation and seismogenic characteristics along the northeast margin of Qinghai -Xizang block 总被引:2,自引:0,他引:2
Introduction The northeast margin of Qinghai-Xizang block has become the place with close attentions from geo-specialists at home and abroad for its significant tectonic movement and intensive seismicity. Quite a number of achievements have been obtained from the studies on geological structures and strong earthquake activities (DING, LU, 1989, 1991; GUO, et al, 1992, 2000; GUO, XIANG, 1993; HOU, et al, 1999; Tapponnier, et al, 1990; Gaudemer, et al, 1995). In the Development Program… 相似文献
3.
Ran Hong-liu 《地震学报(英文版)》2004,17(6):671-677
In recent years, some researchers have studied the paleoearthquake along the Haiyuan fault and revealed a lot of paleoearthquake
events. All available information allows more reliable analysis of earthquake recurrence interval and earthquake rupture patterns
along the Haiyuan fault. Based on this paleoseismological information, the recurrence probability and magnitude distribution
for M≥6.7 earthquakes in future 100 years along the Haiyuan fault can be obtained through weighted computation by using Poisson
and Brownian passage time models and considering different rupture patterns. The result shows that the recurrence probability
of M
S≥6.7 earthquakes is about 0.035 in future 100 years along the Haiyuan fault.
Foundation item: Joint Seismological Science Foundation of China (103034) and Major Research “Research on Assessment of Seismic Safety” from
China Earthquake Administration during the tenth Five-year Plan. 相似文献
4.
I. Anastasopoulos A. Callerio M. F. Bransby M. C. R. Davies A. El Nahas E. Faccioli G. Gazetas A. Masella R. Paolucci A. Pecker E. Rossignol 《Bulletin of Earthquake Engineering》2008,6(4):645-675
Field evidence from recent earthquakes has shown that structures can be designed to survive major surface dislocations. This
paper: (i) Describes three different finite element (FE) methods of analysis, that were developed to simulate dip slip fault
rupture propagation through soil and its interaction with foundation–structure systems; (ii) Validates the developed FE methodologies
against centrifuge model tests that were conducted at the University of Dundee, Scotland; and (iii) Utilises one of these
analysis methods to conduct a short parametric study on the interaction of idealised 2- and 5-story residential structures
lying on slab foundations subjected to normal fault rupture. The comparison between numerical and centrifuge model test results
shows that reliable predictions can be achieved with reasonably sophisticated constitutive soil models that take account of
soil softening after failure. A prerequisite is an adequately refined FE mesh, combined with interface elements with tension
cut-off between the soil and the structure. The results of the parametric study reveal that the increase of the surcharge
load q of the structure leads to larger fault rupture diversion and “smoothing” of the settlement profile, allowing reduction of
its stressing. Soil compliance is shown to be beneficial to the stressing of a structure. For a given soil depth H and imposed dislocation h, the rotation Δθ of the structure is shown to be a function of: (a) its location relative to the fault rupture; (b) the surcharge load q; and (c) soil compliance. 相似文献
5.
Wang Shuang-xu Jiang Zai-sen Chen Wen-sheng Zhang Xi Chen Bing Zhang Si-xin Wang Ji-ying 《地震学报(英文版)》2001,14(2):156-165
The time-space distribution characteristics of fault deformation anomaly in the near-source region and its outlying zone in
the seismogenic process of the Jingtai M
s=5.9 earthquake occurred on June 6, 2000 in Gansu Province is studied preliminarily. The distribution scope of fault deformation
anomaly before the earthquake is wide, the anomaly shape is complicated and the pattern anomalous zone of fault deformation
(strain) information index is obvious. The shape and amplitude of fault deformation anomaly in different regions differ significantly,
which is closely related with the tectonic location of anomaly. The fault deformation anomaly of α, β, and γ phases along
the western segment of Haiyuan fault zone shows the process from the quasi-linearity to non-linearity of fault movement in
the near-source region, matches the high-value anomalous area of fault deformation (strain) information index, and reflects
the high strain accumulation in the seismogenic region. However, the anomaly of abrupt jump and cusp with a large amplitude
occurred in the areas far from the earthquake, such as Liupanshan fault zone which is the tectonic convergent section does
not reflect the strain accumulation of its location, maybe it is a sign that the regional tectonic stress field is strengthened
in the seismogenic process. Based on the above-mentioned facts and combined with the preliminary summary of experiences and
lessons in the intermediate and short-term prediction of the Jingtai M
s=5.9 earthquake, we study and explore the application of fault deformation anomaly to earthquake judgment.
Foundation item: National Key Basic Research Development Program (G1998040703 and G1998040705), and State Scientific and Technological Project
of the “Ninth Five-Year Plan” (96-913-09-01-02-03 and 96-913-09-02-02-03), China. 相似文献
6.
Xue-Ze Wen 《地震学报(英文版)》1993,6(4):993-1004
Spatial distribution of sources of strong and large earthquakes on the Xiaojiang fault zone in eastern Yunnan is studied according
to historical earthquake data. 7 segments of relatively independent sources or basic units of rupture along the fault zone
have been identified preliminarily. On every segment, time intervals between main historical earthquakes are generally characterized
by “time-predictable” recurrence behavior with indetermination. A statistic model for the time intervals between earthquakes
of the fault zone has been preliminarily established. And a mathematical method has been introduced into this paper to reckon
average recurrence interval between earthquakes under the condition of having known the size of the last event at a specific
segment. Based on these, ranges of the average recurrence intervals given confidence have been estimated for events of various
sizes on the fault zone. Further, the author puts forward a real-time probabilistic model that is suitable to analyze seismic
potential for individual segments along a fault zone on which earthquake recurrence intervals have been characterized by quasi-time-predictable
behavior, and applies this model to calculate conditional probabilities and probability gains of earthquake recurring on the
individual segments of the Xiaojiang fault zone during the period from 1991 to 2005. As a consequence, it has shown that two
parts of this fault zone, from south of Dongchuan to Songming and from Chengjiang to Huaning, have relatively high likelihoods
for strong or large earthquake recurring in the future.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 322–330, 1993. 相似文献
7.
Evolution of cumulative Coulomb failure stress in northeastern Qinghai-Xizang (Tibetan) Plateau and its effect on large earthquake occurrence 总被引:3,自引:0,他引:3
We simulate accumulative Coulomb failure stress change in a layered Maxwell viscoelastic media in the north-eastern Qinghai-Xizang(Tibetan)Plateau since 1920.Lithospheric stress/strain evolution is assumed to be drivenby dislocations of large earthquakes(M≥7.0)and secular tectonic loading.The earthquake rupture parameters suchas the fault rupture length,width,and slip are either adopted from field investigations or estimated from their sta-tistic relationships with the earthquake magnitudes and seismic moments.Our study shows that among 20 largeearthquakes(M≥7.0)investigated,17 occurred in areas where the Coulomb failure stress change is positive,with atriggering rate of 85%.This study provides essential data for the intermediate to long-term likelihood estimation oflarge earthquakes in the northeastern Tibetan Plateau. 相似文献
8.
An interpretation of the type, size, and location of the source of the Aleutian earthquake on April 1, 1946, which was characterized
by the highest intensity (I = 4), is proposed. The earthquake source is a subvertical reverse fault striking along the island arc and dipping at an angle
of 85° toward the deep-sea trench. The reverse fault is located in the lower part of the island slope, within the eastern
termination of the Aleutian terrace. The western end of the reverse fault is located in the area of the Krenitsyn Islands
(λ ∼ 165°W), where the pattern of isobaths changes, and an abrupt widening of the shelf part of the Fox Islands takes place.
Large (M
S ∼ 7) shocks, preceding the 1946 earthquake, occurred here in 1940, 1942, and 1944. Structural inhomogeneities in the island
slope in the area of the Sanak Islands (λ ∼ 162°W) determine the eastern edge of the source-reverse fault, whose length within
the specified boundaries is about 200 km. The mean magnitude of the earthquake corresponding to such a source is ∼8.3. According
to the regular relation between the rupture length and the mean movement, the vertical displacement of the ocean floor in
the source region could attain 5–6 m. A significant vertical displacement of the ocean floor over its large length (∼200 km)
was responsible for the high tsunamigenic ability of this earthquake. A favorable combination in the source area of the topographic
and other conditions necessary for the tsunami formation could additionally contribute to an increase in the intensity of
the tsunami. The earthquake of April 1, 1946, in the Fox Islands, as well as the tsunamigenic earthquakes of March 9, 1957,
in the Andreanof Islands and February 4, 1965, in the Rat Islands, does not belong to the class of “slow” earthquakes. 相似文献
9.
通过卫星影像解译和野外实地调查,获得滇西南地区孟连断裂的几何特征和活动性参数。孟连断裂总体走向NE-NEE向,不具有明显的分段性,连续性较好。断裂从单侧控制着沿线的勐滨、孟连和勐马三个新生代盆地的发育。断裂沿线地貌以线性较好的断层谷、断层崖和断层陡坎为主,并发育多级左旋位错的河流、冲沟和阶(台)地等,观测到的最小左旋位错约为7 m。采用高精度Li-DAR测量方法,对4处典型水平位错地貌进行精细测量,根据获得的相应地貌面年代,得到孟连断裂晚第四纪以来平均左旋走滑速率为2.2±0.4 mm/a。其结果与滇西南地区其他NE向左旋走滑断裂滑动速率相当,反映了区域构造活动的整体协调性。根据跨断层地质体最大左旋位错量9.5±1.8 km,估算断裂开始左旋走滑的时代为距今4.7±1.6 Ma左右,即中新世中晚期。 相似文献
10.
Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic
stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent
with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks
occur in regions with crystalline bedrocks. Then we collected waveform data from National Digital Seismograph Network and
regional seismograph network of China, and employed “Cut and Paste” method to obtain focal mechanisms and depths of the big
aftershocks (M⩾5.6). While most of those aftershocks show thrust mechanism, there are some strike slip earthquakes in the northern-most
end of the rupture. Focal mechanisms show that the events located on the southern part of central Beichuan-Yingxiu Fault (BY)
are mainly thrust earthquakes, which is consistent with initial mechanism of the main shock rupture. In the north part the
aftershocks along the BY are also dominated by thrust slip, which is quite different from the right slip rupture of the main
shock. Around Qingchuan-Pingwu Fault, the focal mechanisms are dominated by right-slip rupture with large depths (∼18 km).
So we suspected that in the north part the main shock might rupture on two faults: Beichuan Fault and Qingchuan-Pingwu Fault.
The complex pattern of aftershock mechanisms argues for presence of a complicated fault system in the Longmenshan area.
Supported by Knowledge Innovation Project of Chinese Academy of Sciences (Grant Nos. KZCX3-SW-153, KZCX2-YW-116-1), National
Natural Science Foundation of China (Grant No. 40604004), and National Basic Technology R & D Program (Grant No. 2006BAC01B02-01-02). 相似文献
11.
Study on the pattern and mode of vertical crustal deformation during the seismogenic process of intraplate strong earthquakes 总被引:3,自引:0,他引:3
Studyonthepatternandmodeofverticalcrustaldeformationduringtheseismogenicprocessofintraplatestrongearthquakes杨国华,桂昆长,巩曰沐,杨春花,韩... 相似文献
12.
G. N. Kopylova G. M. Steblov S. V. Boldina I. A. Sdel’nikova 《Izvestiya Physics of the Solid Earth》2010,46(1):47-56
A method for point estimation of coseismic volume deformation from amplitudes of earthquake-induced jumps in the water level
and from the tidal sensitivity of the water level is presented. Application of this method is illustrated by six Kamchatka
earthquakes of 1997–2004 with M
w
= 6.2–7.8 that occurred 128–316 km from the YuZ-5 well. Estimates of coseismic deformation provided by the level gage observations
and by the model agree in amplitude and sign. The model reproduces an extended dislocation source in a homogeneous elastic
isotropic half-space. Source rupture parameters correspond to focal mechanisms from the CMT international catalog. Consistence
in experimental and theoretical estimates of the volume coseismic deformation indicates the high strain-resistance properties
of YuZ-5 borehole and the possibility of quantitative estimation of seismotectonic deformation from high-precision water level
measurements with time resolution not lower than 10 minutes. 相似文献
13.
隧道作为重要的轨道交通工程,近年来在地震中受到了不同程度的破坏,特别是跨断层的隧道,其抗震性能越来越受到人们的关注。为了能够更好地评价隧道的整体损伤情况及把握其损伤特征,以北京地铁7号线为研究对象,利用有限元软件ABAQUS建立模型,采用拟静力法,以隧道直径变化率作为损伤指标分析了隧道在走滑断层以及逆断层位错作用下的损伤特征,对比了两种断层位错作用下损伤状态与地震强度之间的关系、损伤范围和位置以及损伤程度。结果表明:跨断层隧道在断层错动作用下损伤只发生在断层带附近;当震级处于6.0~8.0级时,隧道衬砌损伤程度随震级的增大而增大;在覆土厚度相同的条件下,同震级时逆断层位错作用下隧道损伤程度要比走滑断层作用下大得多;走滑断层位错作用下隧道结构损伤主要发生在拱腰处,逆断层位错作用下主要发生在拱肩-拱脚以及拱顶-拱底处。 相似文献
14.
为了把较高空间分辨率区域的GPS观测资料用于强震地点预测,提出了活动断裂带构造变形定量分析方法. 该方法主要通过沿断裂带主断层线两侧划分若干形变单元,求解各单元的几何变形和相对错动参数等,定量估算断裂带各分段滑动及应变速率;进一步基于断裂带整体变形的协调性,确定可能存在的异常段及其性质和程度. 利用1991——2001年GPS速度场资料对川滇块体东边界带的实例分析显示, 则木河-小江断裂的冕宁-宁南-东川一带,为主断层活动相对闭锁而左旋剪应变积累速度较高的异常段. 相似文献
15.
Large earthquakes in the macquarie ridge complex: Transitional tectonics and subduction initiation 总被引:1,自引:0,他引:1
Larry J. Ruff Jeffrey W. Given Chris O. Sanders Christine M. Sperber 《Pure and Applied Geophysics》1989,129(1-2):71-129
While most aspects of subduction have been extensively studied, the process of subduction initiation lacks an observational foundation. The Macquarie Ridge complex (MRC) forms the Pacific-Australia plate boundary between New Zealand to the north and the Pacific-Australia-Antarctica triple junction to the south. The MRC consists of alternating troughs and rises and is characterized by a transitional tectonic environment in which subduction initiation presently occurs. There is a high seismicity level with 15 large earthquakes (M>7) in this century. Our seismological investigation is centered on the largest event since 1943: the 25 MAY 1981 earthquake. Love, Rayleigh, andP waves are inverted to find: a faulting geometry of right-lateral strike-slip along the local trend of the Macquarie Ridge (N30°E); a seismic moment of 5×1027 dyn cm (M
w=7.7) a double event rupture process with a fault length of less than 100km to the southwest of the epicenter and a fault depth of less than 20km. Three smaller thrust earthquakes occurred previous to the 1981 event along the 1981 rupture zone; their shallow-dipping thrust planes are virtually adjacent to the 1981 vertical fault plane. Oblique convergence in this region is thus accommodated by a dual rupture mode of several small thrust events and a large strike-slip event. Our study of other large MRC earthquakes, plus those of other investigators, produces focal mechanisms for 15 earthquakes distributed along the entire MRC; thrust and right-lateral strike-slip events are scattered throughout the MRC. Thus, all of the MRC is characterized by oblique convergence and the dual rupture mode. The true best-fit rotation pole for the Pacific-Australia motion is close to the Minster & Jordan RM2 pole for the Pacific-India motion. Southward migration of the rotation pole has caused the recent transition to oblique convergence in the northern MRC. We propose a subduction initiation process that is akin to crack propagation; the 1981 earthquake rupture area is identified as the crack-tip region that separates a disconnected mosaic of small thrust faults to the south from a horizontally continuous thrust interface to the north along the Puysegur trench. A different mechanism of subduction initiation occurs in the southernmost Hjort trench region at the triple junction. newly created oceanic lithosphere has been subducted just to the north of the triple junction. The entire MRC is a soft plate boundary that must accommodate the plate motion mismatch between two major spreading centers (Antarctica-Australia and Pacific-Antarctica). The persistence of spreading motion at the two major spreading centers and the consequent evolution of the three-plate system cause the present-day oblique convergence and subduction initiation in the Macquarie Ridge complex. 相似文献
16.
The spatial and temporal distributions of acoustic emission (AE) during the deformation of samples containing an inhomogeneous fault have been studied under biaxial compression. The results show that the fault strength and the duration from loading to failure increase and the failure mode changes from abrupt instability to gradual failure with increase of lateral stress σ2. The pre-setting fault and its heterogeneity play an important role in controlling AE spatial distribution during the deformation. The basic pattern of AE spatial distribution is controlled by the pre-setting fault, especially the parts with inhomogeneous strength and the strong segment, and the localization of fracturing starts from the positions with inhomogeneous strength, With increase of σ5, the dense AE distribution area spreads from the positions with inhomogeneous strength to the whole strong segment gradually. AE temporal sequence is significantly affected by σ2. The fault shows abrupt instability in final failure, which occurs on a background of "enhancement-quiescence" in microfracturing activity at lower σ2. At higher σ5, the fault shows gradual failure, and AE occurrence rate increases continuously and AER increase exponentially before and after the failure, The effect of σ2 on b-value is also remarkable, b-value shows precursory decrease in the weakening stage when fault behavior is abrupt instability, but it shows balanced change when fault behavior is gradual failure, 相似文献
17.
Dynamic simulation of interactions between major earthquakes on the Xianshuihe fault zone 总被引:3,自引:0,他引:3
The authors firstly evaluate the strain accumulation rate of the Xianshuihe fault zone based on earth- quake activity. We calculated the stress and seismic moment accumulation rate for each subsection of the Xianshuihe fault zone based on the distribution of geological slip rate and GPS survey results. According to the results, we get the recurrence intervals of characterized earthquakes on each sub- section respectively. A three-dimensional finite element model for western Sichuan is constructed to discuss the earthquakes triggering among major earthquakes (M>6.7) that occurred along the Xianshuihe fault zone since 1893. The calculated Coulomb failure stress changes (ΔCFS) show that 5 of the 6 earthquakes with Ms>6.7 were triggered by positive ΔCFS. The interactions between major earthquakes not only influence recurrence intervals of characterized earthquakes on each subsection, but also change recurrence behavior of major earthquakes along the whole fault zone. 相似文献
18.
Fracture characteristics of the 1997 Jiashi, Xinjiang, China, earthquake swarm inferred from source spectra 总被引:2,自引:0,他引:2
SHI-YONG ZHOU 《地震学报(英文版)》2000,13(2):125-135
Broadband P and S waves source spectra of 12 MS5.0 earthquakes of the 1997 Jiashi, Xinjiang, China, earthquake swarm recorded at 13 GDSN stations have been analyzed. Rupture size and static stress drop of these earthquakes have been estimated through measuring the corner frequency of the source spectra. Direction of rupture propagation of the earthquake faulting has also been inferred from the azimuthal variation of the corner frequency. The main results are as follows: ①The rupture size of MS6.0 strong earthquakes is in the range of 10~20 km, while that of MS=5.0~5.5 earthquakes is 6~10 km.② The static stress drop of the swarm earthquakes is rather low, being of the order of 0.1 MPa. This implies that the deformation release rate in the source region may be low. ③ Stress drop of the earthquakes appears to be proportional to their seismic moment, and also to be dependent on their focal mechanism. The stress drop of normal faulting earthquakes is usually lower than that of strike-slip type earthquakes. ④ For each MS6.0 earthquake there exists an apparent azimuthal variation of the corner frequencies. Azimuthally variation pattern of corner frequencies of different earthquakes shows that the source rupture pattern of the Jiashi earthquake swarm is complex and no uniform rupture expanding direction exists. 相似文献
19.
赵和云 《地震学报(英文版)》1994,7(3):465-474
ThepatterncharacteristicsofthetendencyvariationsofearthresistivityanditsrelationtoearthquakesHe-YunZHAO(赵和云)(EarthquakeResear... 相似文献
20.
This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip (normal and thrust) fault rupture. The first two steps dealing with fault rupture propagation in the free-field were presented in the companion paper. This paper develops an approximate analytical method to analyze soil-foundation-structure interaction (SFSI), involving two additional phenomena: (i) fault rupture diversion (Step 3); and (ii) modification of the vertical displacement profile (Step 4). For the first phenomenon (Step 3), an approximate energy-based approach is developed to estimate the diversion of a fault rupture due to presence of a raft foundation. The normalized critical load for complete diversion is shown to be a function of soil strength, coefficient of earth pressure at rest, bedrock depth, and the horizontal position of the foundation relative to the outcropping fault rupture. For the second phenomenon (Step 4), a heuristic approach is proposed, which "scans" through possible equilibrium positions to detect the one that best satisfies force and moment equilibrium. Thus, we account for the strong geometric nonlinearities that govern this interaction, such as uplifting and second order (P-△) effects. Comparisons with centrifuge-validated finite element analyses demonstrate the efficacy of the method. Its simplicity makes possible its utilization for preliminary design. 相似文献