西安南五台隧道新奥法设计施工          下载免费PDF全文

李堂磊  黄真萍 《探矿工程》2005,32(11):59-61

结合西安南五台隧道(第五标段)的开挖、初期支护、现场量测及二次衬砌施工的工程实例，介绍了新奥法在隧道设计施工中的应用。  相似文献   

管道衬砌内水外渗对边坡稳定影响的数值模拟   总被引：6，自引：0，他引：6  

肖明  傅志浩  叶超 《岩土力学》2007,28(2):302-306

根据钢筋混凝土受拉开裂特性，通过混凝土开裂后钢筋和混凝土联合承载原理，提出了在内水压作用下混凝土衬砌开裂的裂缝宽度估算公式。根据开裂衬砌内水外渗的规律，提出了高压管道内水外渗与混凝土衬砌裂缝宽度相互影响的有限元迭代计算分析方法。该方法将内水压荷载分解为起裂荷载和破坏荷载，对混凝土衬砌起裂荷载采用一次加载，对破坏荷载采用分级加载迭代，由此较好地反映衬砌开裂和渗流耦合作用效应。根据渗流荷载对边坡的破坏作用，提出了对边坡稳定判断的思路。通过对实际工程的分析计算，论证了高压管道内水外渗对边坡的稳定影响, 为内水外渗与应力场耦合分析提供了一种有效的计算方法。  相似文献   

旋挖钻进技术在澳门地下重型停车场工程中的应用     

孙垦耘 《中国煤田地质》2007,19(1):74-75

澳门地下重型停车场工程地段属人工堆填整平的山丘地形，地层结构从上而下为杂填土、冲积沙层、风化程度不同花岗岩带，使用旋挖钻机进行钻孔灌注桩施工时，因地层岩性因素，易出现漏浆、孔壁坍塌及埋钻事故。通过选用适岩性不同的钻头、合理埋设钢护筒位置、调配性能适宜的泥浆及规范混泥土灌注流程，保证了旋挖钻机在成孔过程中孔壁的稳定性，解决了塌孔埋钻问题，提高了钻孔灌注桩的成孔效率。  相似文献   

偏心水平荷载下内藏钢桁架混凝土核心筒抗震试验研究     

常卫华  曹万林  张建伟  赵长军 《世界地震工程》2007,23(4):112-118

对两个1／6缩尺的核心筒结构模型进行了偏心水平荷载作用下的低周反复荷载试验研究，其中包括一个普通混凝土核心筒和一个内藏钢桁架混凝土组合核心筒。在试验的基础上，分析了两个试件的承载力、刚度、延性、滞回特性、耗能能力、破坏特征以及抗震机理。试验研究表明：偏心水平荷载作用下，内藏钢桁架混凝土组合核心筒比普通混凝土核心筒抗震能力显著提高。  相似文献   

Performance evaluation and damage assessment of steel frame buildings under main shock–aftershock earthquake sequences     

Quanwang Li  Bruce R. Ellingwood 《地震工程与结构动力学》2007,36(3):405-427

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An energy‐based damage model for seismic response of steel structures     

A. Benavent‐Climent 《地震工程与结构动力学》2007,36(8):1049-1064

This paper proposes a new model for quantifying the damage in structural steel components subjected to randomly applied flexural/shear stress reversals, such those induced by earthquakes. In contrast to existing approaches that consider the damage as a combination of the global amount of dissipated energy and maximum displacement, the proposed model represents the damage by two parameters: (a) the total dissipated energy and (b) the portion of the energy consumed in the skeleton part of the load–displacement curve. These parameters are employed to define a single ‘damage index’, which measures the level between 0 (no damage) and 1 (failure). The proposed model takes into account that the ultimate energy dissipation capacity of the steel component is path‐dependent and can change throughout the entire response duration. The new model is derived from low‐cycle fatigue static tests of round steel rods and steel plates subjected to bending and shear. The accuracy of the model is verified experimentally through dynamic real‐time shaking table tests. From these tests, it is observed that the proposed model measures the level of damage at any stage of the loading process reasonably well and predicts the failure of the structural component accurately. The model can be easily implemented in a computer program to assess the level of seismic damage and the closeness to failure in new structures or to evaluate the safety of existing ones. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Estimation of seismic drift and ductility demands in planar regular X‐braced steel frames     

Theodore L. Karavasilis  Nikitas Bazeos  Dimitri E. Beskos 《地震工程与结构动力学》2007,36(15):2273-2289

This paper summarizes the results of an extensive study on the inelastic seismic response of X‐braced steel buildings. More than 100 regular multi‐storey tension‐compression X‐braced steel frames are subjected to an ensemble of 30 ordinary (i.e. without near fault effects) ground motions. The records are scaled to different intensities in order to drive the structures to different levels of inelastic deformation. The statistical analysis of the created response databank indicates that the number of stories, period of vibration, brace slenderness ratio and column stiffness strongly influence the amplitude and heightwise distribution of inelastic deformation. Nonlinear regression analysis is employed in order to derive simple formulae which reflect the aforementioned influences and offer a direct estimation of drift and ductility demands. The uncertainty of this estimation due to the record‐to‐record variability is discussed in detail. More specifically, given the strength (or behaviour) reduction factor, the proposed formulae provide reliable estimates of the maximum roof displacement, the maximum interstorey drift ratio and the maximum cyclic ductility of the diagonals along the height of the structure. The strength reduction factor refers to the point of the first buckling of the diagonals in the building and thus, pushover analysis and estimation of the overstrength factor are not required. This design‐oriented feature enables both the rapid seismic assessment of existing structures and the direct deformation‐controlled seismic design of new ones. A comparison of the proposed method with the procedures adopted in current seismic design codes reveals the accuracy and efficiency of the former. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Transient response in steel moment frames caused by brittle connection fracture     

Janise E. Rodgers  Stephen A. Mahin 《地震工程与结构动力学》2007,36(15):2423-2444

Brittle fractures occurring at the beam–column connections of welded steel moment frames, such as those observed following the M_w 6.7 1994 Northridge earthquake, result in sudden decreases in connection strength and stiffness. These changes lead to various types of transient dynamic behavior at the local and global levels. The effects on global acceleration include highly transient, high‐frequency waveforms that occur immediately following fracture and decay quickly. The theoretical basis for the occurrence of these transient waveforms is examined and their presence in structural analysis results is demonstrated. Results from shaking table experiments on a simple steel moment frame with fracturing connections show that transient accelerations are consistently observed following fracture. These experiments and analyses show that, due to their short duration, the transient acceleration waveforms do not cause any sudden changes in the global lateral displacement response of typical building structures. Therefore, these global acceleration transients have relatively benign effects on overall system behavior despite their relatively large amplitudes. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

钢框架结构的非线性静力抗震可靠性分析:Ⅰ有限元反应及其灵敏度   总被引：2，自引：1，他引：2  

吕大刚  李晓鹏  胡晓琦  王光远 《地震工程与工程振动》2007,27(5)

作为一种随机有限元方法,有限元可靠度方法通过有限元反应灵敏度分析将结构可靠度分析的近似解析方法与结构确定性分析的有限元方法结合起来,可以有效地处理结构反应是基本随机变量的隐式函数这一难题,因此成为大型复杂结构可靠度分析的有效工具。采用基于位移的非线性纤维梁柱单元对钢框架结构进行有限元建模,推导了单元与截面的基本方程。针对基于位移的纤维梁柱单元,采用逐级递进方式,分别推导了整体级、单元级、截面级和材料级的有限元反应灵敏度直接微分表达式。研究结果可为采用FORM或SORM等近似解析法进行钢框架结构的非线性静力有限元可靠性分析提供算法支持和编程依据。  相似文献   

Stress analysis of buried steel pipelines at strike-slip fault crossings   总被引：3，自引：0，他引：3  

Dimitrios K. Karamitros  George D. Bouckovalas  George P. Kouretzis 《Soil Dynamics and Earthquake Engineering》2007,27(3):200-211

Existing analytical methods for the stress analysis of buried steel pipelines at crossings with active strike-slip faults depend on a number of simplifications, which limit their applicability and may even lead to non-conservative results. The analytical methodology presented herein maintains the well-established assumptions of existing methodologies, but also introduces a number of refinements in order to achieve a more wide range of application without any major simplicity sacrifice. More specifically, it employs equations of equilibrium and compatibility of displacements to derive the axial force applied on the pipeline and adopts a combination of beam-on-elastic-foundation and elastic-beam theory to calculate the developing bending moment. Although indirectly, material and large-displacement non-linearities are also taken into account, while the actual distribution of stresses on the pipeline cross-section is considered for the calculation of the maximum design strain. The proposed methodology is evaluated against the results of a series of benchmark 3D non-linear analyses with the finite element method. It is shown that fairly accurate predictions of pipeline strains may be obtained for a wide range of crossing angles and fault movement magnitudes encountered in practice.  相似文献