美国西部地震烈度衰减规律

在国家和地区地震动区划和重大工程的地震安全性评价工作中，区域地震动衰减规律的确定是重要环节，而借用法是目前常用的建立区域地震动衰减的方法。我国借用法通常都把美国西部作为参考地区，但一般都采用调整美国学者已有烈度衰减规律的办法确定美国西部烈度衰减规律。本文讨论美国西部已有烈度衰减规律，并直接采用美国西部烈度调查资料建立烈度衰减规律，结果可供我国工程地震工作者参考。     

液化地基的评价及处理的体会

合理评价液化地基及采用科学的处理方案对工程建设有重要意义，总结了影响地基液化的主要因素及液化判定的一般方法，提出了一种新的液化判定方法——归一法。结合实例就液化地基的设计与处理谈了一些体会。     

1995年永登地震山体变形计算机模拟与机理分析

1995年甘肃永登5．8级地震引起了黄土山梁的酥裂震陷，说明黄土在较小震级下也会有失稳现象．利用三维土体的有限元计算方法，对永登地震山体变形进行了计算机模拟，并定量地分析了变形的机理。     

Principle and mathematical method for inverting stress State of a medium from the remote sensing data

It has been proved through experiments that the electromagnetic radiation energy of a substance will vary when stress acts on the substance. This moment, the electromagnetic radiation energy (observation value) received by the remote sensor is triggered not only by the substance temperature and also by the stress. Separating quantitatively these two kinds of electromagnetic radiation energy and then inversing the actual temperature state and stress state of a medium is a matter with practical significance in earthquake prediction and stability monitoring for the large-scale geotechnical engineering. In this paper the principle and the mathematical method for inversing stress by using multiband remote sensing data are discussed in detail. A calculation example is listed.     

A synthetic optimization analysis method on structures with viscoelastic dampers

The paper introduces a synthetic optimization analysis method of structures with viscoelastic (VE) dampers, namely the simplex method. The optimal parameters and location of VE dampers can be determined by this method. Numerical example and a shaking table test about reinforced concrete structures with VE dampers show that the seismic responses of structures will be reduced more effectively when the parameters and location of VE dampers are designed in accordance with the results calculated by the simplex method.     

Anelastic structure of the upper mantle beneath the northern Philippine Sea

We investigated the upper mantle anelastic structure beneath the northern Philippine Sea region, including the Izu-Bonin subduction zone and the Shikoku Basin. We used regional waveform data from 69 events in the Pacific and the Philippine Sea slabs, recorded on F-net and J-array network broadband stations in western Japan. Using the S–P phase pair method, we obtained differential attenuation factors, δt^*, which represent the relative whole path Q. We conducted a tomographic inversion using 978 δt^* values to invert for a fine-scale (50–100 km) three-dimensional anelastic structure.

The results shows two high-Q regions (Q_P>1000) which are consistent with the locations of the Pacific and the Philippine Sea slabs. Also there is a low-Q (Q_P110) area extending to the deeper parts (350–400 km) of the model just beneath the old spreading center and the Kinan Seamount Chain in the Shikoku Basin. A small depth dependence of the laterally averaged Q_P was found, with values of 266 (0–250 km), 301 (250–400 km), and 413 (400–500 km).     

Decoupled seismic analysis of an earth dam

The seismic stability of an earth dam is evaluated via the decoupled displacement analysis using the accelerograms obtained by ground response analysis to compute the earthquake-induced displacements. The response analysis of the dam is carried out under both 1D and 2D conditions, incorporating the non-linear soil behaviour through the equivalent linear method. Ten artificial and five real accelerograms were used as input motions and four different depths were assumed for the bedrock.1D and 2D response analyses were in a fair agreement with the exception of the top third of the dam where only a 2D modelling of the problem could ensure that the acceleration field is properly described. The acceleration amplification ratio obtained in the 2D analyses was equal to about 2 in all the cases considered, consistently with data from real case histories.The maximum permanent displacements computed by the sliding block analysis were small, being less than 10% of the service freeboard; a satisfactory performance of the dam can then be envisaged for any of the seismic scenarios considered in the analyses.     

Application of extended distinct element method with lattice model to collapse analysis of RC bridges

This paper proposes a simple lattice model for collapse analysis of RC bridges subjected to earthquakes by using the extended distinct element method (EDEM). In the model, a concrete element consists of lumped masses connected to one another by springs, and a reinforcement bar is represented by a discrete model or an integrated model. The proposed lattice model is simple but its parameters are reasonably defined. It has fewer element nodes and connecting springs, which will be of benefit by shortening the CPU time. The processes to determine the initial stiffness of concrete and steel springs, the parameters of the constitutive model and the fracture criteria for springs are described. A re‐contact spring model is also proposed to simulate the re‐contact of the concrete after fracture of springs; and a general grid searching method is used to decrease the CPU time for judging re‐contact after fracture. The lattice model is assessed by numerical simulations and experiments. As an application, a damaged single‐column pier subjected to the Kobe Earthquake in 1995 is analysed by EDEM with the proposed model. The simulation results indicate that the proposed model predicts well qualitatively the collapse process of RC bridges. Copyright © 2003 John Wiley & Sons, Ltd.     

压裂井经济分析的优化方法

水力压裂是油气井增产的一项重要技术措施。压裂效果的经济评价，实际上是一个压裂设计的优化过程。研究经济问题即为研究压裂优化问题。提出了压裂井的施工费用计算方法和贴现率、净收入、净现值的计算公式，并对压裂井进行了经济分析，给出了压裂设计优化的步骤。建立了八屋—后五家户气田压裂经济评价模型，并应用到实际施工现场。使油气单井产量比过去增加2～3倍。