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This study deals with the formulation of an analytical solution for load transfer in drilled shaft and its application. The emphasis is on quantifying the mobilization of side resistances, which are closely related to shear behaviors of the concrete-rock interface. In this modelling, the side resistance is idealized by using elasticity-brittleness-plasticity, and a simple slip-line field is built to identify the critical shear displacement. The closed-form solution of load transfer is obtained by using the proposed shear model. Comparison between predictions and field observations is also made to validate performance of the proposed method. 相似文献
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在广州市目标区内的主要活动断层危险性评价的基础上,综合活断层探测的研究成果和资料,对于具有潜在发震可能的主要断层,基于凹凸体震源模型建模理论进行了特征计算模型的建模。根据断层地震危险性分析确定的断层发震震级和几何参数,进行了断层的宏观参数和微观参数的设定。为通过复核预测方法计算与合成近断层强地震动场和城市危害性评价提供了科学的依据。 相似文献
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A model has been developed to simulate the statistical and mechanical nature of rupture on a heterogeneous strike-slip fault. The model is based on the progressive failure of circular asperities of varying sizes and strengths along a fault plane subjected to a constant far-field shear displacement rate. The basis of the model is a deformation and stress intensity factory solution for a single circular asperity under a unidirectional shear stress. The individual asperities are unified through the fault stiffness and the far-field stress and displacement. During fault deformation asperities can fail and reheal, resulting in changes in the local stresses in the asperities, stress drops, and changes in the stiffness of the fault. Depending on how the stress is redistributed following asperity failure and on the strenghts of the neighboring asperities an earthquake event can be the failure of one or more asperities. Following an earthquake event seismic source parameters such as the stress drop, energy change, and moment magnitude are calculated. Results from the model show a very realistic pattern of earthquake rupture, with reasonable source parameters, the proper magnitude-frequency behavior, and the development of characteristic earthquakes. Also the progression ofb-values in the model gives some insight into the phenomenon of self-organized criticality. 相似文献
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Teleseismic and strong-motion data are inverted to determine the rupture process during the November 1999 Düzce earthquake in NW Turkey. The fault geometry, rise time and rupture velocity are determined from the aftershock distribution and preliminary inversions of the teleseismic data. Joint inversion of the teleseismic and strong-motion data is then carried out for the slip distribution. We obtain the strike 264°, dip 64°, rake −172°, seismic moment 5.0×1019 N m (Mw 7.1), and average stress drop 7 MPa. This earthquake was characterized by bilateral fault rupture and asymmetric slip distribution. Two asperities (areas of large slip) are identified, the eastern one being 1.5 times larger than the western one. The derived slip distribution is consistent with the aftershock distribution, surface rupture and damage. The point of rupture initiation in this Düzce earthquake coincided with the eastern tip of the aftershock distribution of the August 1999 Izmit earthquake. 相似文献
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Tomomi Okada Akira Hasegawa Jun''ichi Suganomata Norihito Umino Haijiang Zhang Clifford H. Thurber 《Tectonophysics》2007,430(1-4):67-81
A shallow M6.4 inland earthquake occurred on 26 July 2003 in the northern part of Miyagi Prefecture, northeastern Japan. This earthquake was a typical inland thrust earthquake, a type that is common in NE Japan. We obtained a detailed seismic velocity structure in the focal area of this earthquake by the double-difference tomography method. Arrival-time data came from temporary seismic stations deployed above the mainshock fault plane. Both the P-wave and S-wave velocities in the hanging wall were lower than those in the footwall. Aftershocks were aligned along a zone where the seismic velocity changes rapidly. This is consistent with the interpretation that the 2003 northern Miyagi earthquake occurred along a fault that acted as a normal fault in the Miocene and has been reactivated as a reverse fault under the present compressional stress regime. The large slip area by the main shock rupture (asperity) corresponds to an area with relatively high P- and S-wave velocities. A zone with low Vp/Vs was detected along the aftershock area. One of the possible causes of this low-Vp/Vs zone is the existence of high-aspect-ratio pores that contain water. Hypocenters of the main shock, largest foreshock, and largest aftershock are also located within the low-Vp/Vs zone. 相似文献
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This paper presents a joint constitutive model that considers separately the mechanical contribution of waviness and unevenness of a joint to shear behaviour. The critical asperities for waviness and unevenness are determined from geometric properties in a lab-scale joint. The wear process is employed to model the degradation in dilation and strength during shear. From dimensional analysis, asperity degradation constants are developed using geometric parameters including asperity angle, wavelength, and amplitude as well as rock strength and stress. The applicability of the proposed model was assessed by performing direct shear tests on three joint roughness coefficient (JRC) profiles and providing its correlation with experimental results. Additionally, experimental data taken from literature were used to validate the model’s performance. 相似文献
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In this paper, we studied the slip-weakening instability on a finite and vertical strike-slip fault with asperity. We assumed
that the fault strength is uniform in depth, but it is non-uniform in the strike direction, i.e., there is an asperity on
the fault. The segments of the fault with and without asperity follow the same type of constitutive law, but the peak stresses
are different. The material surrounding the fault is represented by elastic plates whose upper-surface and bottom are stress-free.
We use finite element method to study the evolution of theoretical displacement, stress and strain fields that vary with a
remote displacement. Here the displacement and frictional stress are not given in advance, but are determined in the solving
process. According to the results, we compared the theoretical displacemeut and the distribution of frictional stress on the
fault between the stable and unstable slips. In addition, we compared the results in this paper with known results for the
strike-slip fault with a segment of lower strength. 相似文献
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利用断裂带上的低b值识别凹凸体方法的探讨——以龙门山断裂带和鲜水河断裂带为例 总被引：2，自引：1，他引：1
本文对龙门山断裂带和鲜水河断裂带上1970年以来记录的小震数据进行了收集、整理和分析,采用基于Matlab平台的Zmap软件,去除了断裂带上的丛集数据和余震,划定了有效地震数据的时间和震级范围,通过最大似然法求取了断裂带所在区域的b值分布图。基于b值大小与应力高低成反比的原理,通过断裂带上低b值区识别凹凸体的位置。就龙门山断裂带,通过低b值区识别出的凹凸体的位置与汶川地震发生的起始破裂位置和极震区的位置基本保持一致;而鲜水河断裂带由于受到小震数据的限制,部分段缺失b值分布,但整条断裂带仍可清晰识别出凹凸体位置,且1725年以来的历史强震和1970年以来5级以上的历史地震基本上都位于此区域。断裂带的实例分析结果证明,利用小震数据通过最大似然法计算b值分布图,其相对低b值区与历年强震发生的位置存在较大的相关性,为验证利用低b值区识别凹凸体方法的可行性和实用性提供了有力的证据。 相似文献
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