山丹地应力监测站体应变仪的地震效应

本文简要介绍了山丹地应力监测台站的概况, 用多种方法对该台站安装的TYB-2000A体应变仪在2007年8月至2008年7月记录的174次肘M_s4.0~M_s8.6地震数据进行了处理与分析, 其中汶川地震及余震共85次, 并与其他台站记录的地震资料进行比对, 对记录的应变地震波、同震应变阶跃、地震前后地球自由振荡的变化及其所包含的物理意义等信息深入分析, 揭示出地震前后应变波的变化规律, 为今后的地震预测和灾害防治提供了科学依据.      

固化粉质土应力应变特性试验研究

对固化粉质土进行了单轴和三轴应力应变试验,分析了单轴应力-应变曲线和不固结不排水三轴应力-应变曲线的特点,初步探讨了龄期、固化剂掺量及围压对曲线形状的影响。单轴应力应变试验结果表明,固化粉质土后期的强度和变形特性变化较小,随着固化剂掺量的增加,单轴应力-应变曲线形状变化明显。三轴应力应变试验结果表明,随着固化剂掺量的增加,其破坏应变和破坏偏应力均呈现正向增长的态势,曲线在高围压下呈现弱软化型,在较低围压时呈现软化型。     

桩（墙）单位侧摩阻力与轴向应变关系的解析解及其应用

根据弹性力学原理,提出了模型筒桩（闭合墙）的简化力学模型。采用半逆解法先求出桩左右侧受均布摩阻力、桩顶受均布荷载两种情况下的应力分量,根据叠加原理得出桩两侧均受相同摩阻力、桩顶受均布荷载情况下的应力分量。据此推导了普通桩基的轴力和侧摩阻力计算式,分析结果表明,该计算式与传统计算方法是一致的。当桩壁两侧受不同大小的侧摩阻力、桩顶受均布荷载时,仍采用叠加原理求得各应力分量,进而求得桩表面处的轴向应变与单位侧摩阻力关系的解析解。通过矩形闭合墙基础模型试验实例,对该解析解的应用方法加以说明。该解析解的求出,为竖向载荷试验中模型筒桩（闭合墙）所量测的内外侧应变进行数据处理提供了理论依据,进而为基础-土相互作用研究提供了真实、准确的试验结果。     

构造流变计

根据构造形迹和应变式反演岩石流变性质的方法称为构造流变计,或简称流变计。目前提出的流变计主要有应变折射、能干层褶皱香肠构造、残斑翼尾样式。应变折射、能干层褶皱和香肠构造流变计已进入量化阶段。构造流变计 可用于研究不同尺度地质体的流变结构,也可用来研究地质体的流变学演化,具有很好的发展前景。     

堤下爆炸法处理淤泥地基新工艺的理论、实验及工程应用(Ⅱ)桩对桩间抛石棱体下爆炸挤淤的动力响应

本文是堤下爆炸法处理淤泥地基新工艺的研究及应用的第二部分,着重介绍该工艺应用于桩间棱体的挤淤时,爆炸冲击波和淤泥、石块运动对桩的作用。计算和检测表明,桩体的安全是可以得到保证的。     

Effects of horizontal strain in estimating specific storage and compaction in confined and leaky aquifer systems

 Mathematical and numerical distinctions are made between developments of governing equations involving groundwater flow and granular displacement where (1) only vertical strain and no change in total normal load are assumed, and (2) such limitations are eliminated. The former is referred to here as the Jacob-Terzaghi method; the latter is referred to as the Biot method. Numerical comparisons of drawdown, compaction, and strain are made for hypothetical confined and leaky aquifer systems for one- and three-dimensional strain problems. Simulation results indicate that incorporation of horizontal strain results in reduced drawdowns. Vertical compaction for a specified stress distribution is greatly reduced when horizontal strain is invoked. The distribution of strain components indicates that approximately two-thirds of the total volume strain originates from horizontal compaction in pumped aquifers. Incorporation of horizontal strain also affects the distribution of flux through the overlying confining layer as a function of distance from the pumping well and may ultimately affect the interpretation of aquifer-test data. Received, January 1999 / Revised, May 1999, August 1999 / Accepted, August 1999     

土质边坡剖面上动力响应异常点与潜在滑动面位置的关系研究

通过数值分析对土质边坡动力响应规律进行研究,发现在土质边坡剖面上动力响应参数分布异常的地方跟通常认为的潜在滑动面有很好的对应关系,说明在坡体内发生较大剪应变处土体的动力特性可能已经发生改变,从而使动力传递异常.     

Towards probabilistic seismic performance of vehicle-bridge interaction systems: From stochastic dynamic model to fragility analysis

This paper aims to assess the seismic fragility of vehicle-bridge-interaction (VBI) systems considering the effects of vehicle types, traffic conditions, and road surface qualities. A stochastic nonlinear mechanical model for the earthquake-VBI system is developed, and the fragility functions for the proposed VBI model are derived by considering the relevant probabilistic seismic demand parameters. On the basis of a typical four-span continuous prestressed concrete highway bridge in China, a complete numerical model for the VBI system is built considering multiple uncertainties from bridge and vehicle parameters, as well as the road surface qualities. A total of 120 real ground motion records with different combinations of magnitude-source-to-site distance (M-R) and earthquake intensity characteristics are selected. Meanwhile, 80 scenarios in terms of different combinations of vehicle types, vehicle speeds, and road surface irregularities are defined. In this context, 96,000 nonlinear time-history analyses are performed, and the developed fragility models are applied to the VBI system at both component and system levels. Results indicate that the fragilities of pier drift, bearing shear strain, and the overall VBI system increase with the increase of the vehicle weight or the decrease of the vehicle speed, while the vertical deck displacement is dominated by the vehicle weight. It is also found that the road surface quality has a negligible effect on both component and system fragilities.     

洞体应变对高频气压波响应的传递函数——以陕西宁强台为例

自2011年观测以来,陕西宁强台洞体应变的高频气压效应甚为显著,但其频率依存性至今尚不明晰。为此,本文尝试采用相干函数和传递函数等方法,对该台2019年1月1日—4月2日的洞体应变和气压数据进行了系统诊断。结果表明,在8～40cpd频段内,洞体应变对气压具有较强的频率依赖性,即气压系数和相移均会随频率的变化而呈现非线性变化,其中,最大气压系数为7.80×10^-9/hPa,相位超前可达108.27°,且NS和EW分量的气压响应有所差异。上述结果将有助于该台高频噪声的物理溯源,同时还能为高频气压效应的分频段改正等提供量化依据。