平面应变边界元的位移反分析在阿拉坦隧道中的应用

隧道工程材料特性参数确定一直是人们应用各种方法定量认识的一大工程问题。结合阿拉坦隧道在施工过程中的监控量测所得位移,采用平面应变边界元BPM90程序对隧道岩体物理力学参数进行反分析,并用TSP地质资料说明位移反分析求解的岩体参数有比较高的可信度。     

二维粘弹性问题反分析计算的统一模型

本文就地下工程中二维平面应变问题提出了反演确定洞室围岩初始地应力及其粘弹性参数的统一方法,用五种常见的描述岩土体变形性态的粘弹性模型的参数作反演计算.文中在描述岩土体材料的粘弹性性态的本构方程用统一公式表示,通过论证提出了依据现场量测信息对初始地应力和围岩粘弹性参数进行反演计算的原理、方法和公式,包括可据以进行线弹性反演计算的数值法方程,以及可用于确定围岩粘弹性参数的反演计算方程等.此外,文末还通过算例验证对所提方法的适用性进行了论证.     

堆石在平面应变条件下的强度和应力-应变关系

应用大型平面应变仪,进行了灰岩及细砂岩两种堆石的风干料及饱和固结排水平面应变试验。试验结果表明:1.堆石在平面应变条件下的强度比三轴试验强度高;2.饱和试样强度低于风干料试样强度;3.平面应变条件下的应力-应变关系与三轴试验结果相比较,差别较大,前者呈明显的应变软化特性;4.平面应变条件下堆石泊松比基本上是一常数,而且小主应力σ₃对它影响较小。     

弹性平面问题中的位移函数

由弹性平面问题的Ｎａｖｉｅｒ－Ｌａｍｅ方程组．得到如下位移分量公式这里Φ（ｘ．ｙ）是位移函数．它满足重调和方程Φ，ααββ＝０．同时还得到应力分量同位移函数之间的关系式．文中用两个解析函数表示该位移函数．并导出它们同位移场和应力场之间的关系，这样就可能用复交函数方法来求解弹性平面问题．本文还用位移函数计算了一些例题。     

Development of a Cost‐Effective Wireless Vibration Weigh‐In‐Motion System to Estimate Axle Weights of Trucks

Truck weight data plays an important role in weight enforcement and pavement condition assessment. This data is primarily obtained through weigh stations and Weigh‐In‐Motion (WIM) stations which are currently very expensive to install and maintain. This article presents results of the implementation of an inexpensive wireless sensor‐based vibration WIM system. The proposed wireless sensor network (WSN) consists of acceleration sensors that report pavement vibration; vehicle detection sensors that report a vehicle's arrival and departure times; and an access point (AP) that synchronizes all the sensors and records the sensor data. The article also describes a new method for speed compensation, an energy‐efficient algorithm (adaptive sampling method) to increase battery life, and a new modeling procedure to estimate gross vehicle weights. The system deployed near a conventional WIM system on I‐80W in Pinole, CA passed the accuracy standards for WIM systems and outperformed a nearby commercial WIM station, based on conventional technology.     

基于应变路径法的压入管桩单桩挤土位移场的参数影响分析

分析《基于应变路径法的压入管桩单桩挤土位移研究》中所得的压入管桩单桩挤土位移场解析解,影响因素主要有管桩内外径、桩长、土塞高度最大值。该文分析了不同桩长、ξr(管桩内外径比值)和ξh(土塞高度最大值与桩长的比值)情况下压入管桩压桩产生的挤土位移,研究结果表明:不同桩长情况下竖向和水平挤土位移沿深度方向和径向的分布规律趋于一致;不同ξr、ξh情况下竖向挤土位移沿深度方向和径向的分布规律趋于一致,水平挤土位移沿径向的分布规律趋于一致,沿深度方向的分布规律有所差异。数值上,桩越长、ξr越小、ξh越小,压桩产生的挤土位移越大。为下一步压入管桩的优化设计奠定基础。     

Ermittlung des Aufbaus und der Stoffkennwerte von Außenbauteilen mit Hilfe von In‐situ‐Messungen und FEM‐Berechnungen

Determination of the construction and the material identity values of outside building components with the help of in‐situ measuring procedures and FEM‐simulation calculations. The aims formulated nationwide and internationally to the climate protection can be achieved by combining of the energy‐efficient construction and rehabilitation of the existing buildings. Knowledge about the construction and the material identity values of the warmth‐transferring outside components is a condition for the energetic balance of buildings. The essential information to this can frequently be no more taken from the construction documents particularly for older buildings since they are no longer traceable or incomplete. At the example by univalve and bivalve out‐wall construction it is shown that the thermophysical qualities can be determined with the help of in‐situ measuring procedures and FE‐simulation calculations without destruction.     

平面应变状态的主应力及其对工程的影响

平面应变状态下被动方向的主应力完全取决于土的本构关系,并不总是中主应力,在不同条件下可能为小主应力、中主应力或者大主应力。平面应变状态的主应力对土体强度和变形计算均有重要影响。在使用弹性模型计算高填方土体沉降时,泊松比决定了被动方向主应力的大小,对沉降计算影响很大;由于变形模量通常与小主应力有关,计算变形量时必须首先搞清楚不同工况下,被动方向的主应力到底是大主应力、中主应力还是小主应力,然后才能正确地确定相应的模型参数,进行计算和分析。     

一种双轴岩石平面应变仪的改进和应用

改进制作了一种双轴岩石平面应变实验装置,并自行设计制作了侧向加力器。该装置不仅能施加合适的围压,而且能在实验过程中动态监控围压的变化。对砂岩的实验测试研究表明,这种改进后的双轴岩石平面应变仪能更好地模拟岩石平面应变的条件,具有较好的实用性。     

Large-Scale Plane Strain Compression Tests on Compacted Gravel with Active and Passive Controls

Large-scale plane strain compression tests were performed to study the effect of compaction on strength and deformation properties of gravel. The specimen is rectangular prismatic with dimensions of 50 cm in height and 22 cm times 25 cm in cross-section. By employing well-graded crushed sandstone called as Chiba gravel, five sets of plane strain compression tests were conducted on partially saturated specimens having dry densities in the range of 1.80-2.15 g/cm³ that were prepared using manual or automatic compaction techniques. For each set of tests, one specimen was tested by following the conventional approach called as “passive control” of ε₂, while the second specimen was tested by following a new approach called as “active control” in which one of the two confining plates was allowed to move forward and backward for keeping the locally measured value of ε₂ almost zero. As a result, no significant effect of the active control was found on the stress-strain behavior as compared to the passive control, except for the beginning of shearing. The maximum deviator stresses in the two kinds of plane strain compression tests were about 20% larger than those in the relevant triaxial compression tests under the employed range of the compaction levels.     

计入初始应变项的平面梁单元非线性刚度矩阵

开展平面结构几何非线性分析时经常会遇到杆件含有初始应力力或初始应变的情况。由于非线性刚度矩阵中舍有节点位移，矩阵运算量大，给刚度矩阵的推导带来很大困难。根据平面梁单元几何非线性方程，采用计入初始应力和初始应变项的一般性线弹性应力应变关系，导出了相应的切线刚度矩阵，利用MATLAB数学工具箱，给出了含有初始应力和初始应变的所有刚度矩阵的显式表达式，为程序编制奠定了基础。     

Rate-Dependent Load-Strain Behaviour of Geogrid Arranged in Sand Under Plane Strain Compression

A number of previous experimental studies showed that polymer geogrid reinforcement as well as sand exhibit significantly rate-dependent behaviour. The viscous properties of polymer geogrids and Toyoura sand were independently evaluated by changing stepwise the strain rate as well as performing sustained loading and load/stress relaxation tests during otherwise monotonic loading in, respectively, tensile loading tests and drained plane strain compression (PSC) tests. The viscous properties of the two types of material were separately formulated in the same framework of non-linear three-component rheology model. The viscous response of geogrid-reinforced sand in PSC is significant, controlled by viscous properties of geogrid and sand. Local strain distributions in the reinforced sand specimen were evaluated by photogrametric analysis and used to determine the time history of the tensile strain in the geogrid. The time history of tensile load activated in the geogrid during sustained loading of reinforced sand specimen was deduced by analysing the measured time history of geogrid strain by the non-linear three-component model. It was found that the tensile load in the geogrid reinforcement arranged in a sand specimen subjected to fixed boundary loads could decrease with time. In that case, the possibility of creep rupture of geogrid is very low.     

超大有轨弧形双开钢闸门平面移位安装技术

以常州钟楼防洪控制工程为例，针对体积较大、吨位较重的结构件无法直接一步吊运到位的难点，对超大有轨弧形双开钢闸门采用平面移位安装技术，满足了”不阻航”、并保证大型结构件在独立门库测量放样的工况下进行安装的条件。实践证明，该工程采用此平面移位技术取得了良好效益，可为同类工程提供经验，其具有广阔的应用前景。     

平面三向应力场中隧洞位移解及变化规律研究

为了揭示复杂应力场中隧洞围岩位移变化规律,基于平面三向应力场中圆形隧洞析解理论,推导了平面三向应力场中隧洞围岩位移解析解,并通过Matlab软件编程,研究了围岩位移随应力场环境的变化规律.结果表明:平面三向应力场中各因素对塑性区半径的影响规律与双向应力场中相似;平面三向应力场中当应力场比例系数λ1=1.0,λ2从1.0...     

基于MATLAB和矩阵位移法的平面杆系结构有限元程序设计

基于MATLAB语言和矩阵位移法思想,进行了平面杆系结构有限元程序设计,并结合实例阐释了其编制思想和使用方法。该程序按分析刚架的一般模式编写,而将连续梁和桁架看作特殊的刚架,从而使其通用于分析刚架、连续梁、桁架及组合结构,对不同类型的结构,都采用统一的分析模式,这对分析组合结构尤其具有优势。该程序充分发挥了MATLAB——矩阵实验室擅长矩阵计算的优势,代码简洁,数据准备简单、计算流程清晰、结果输出可选,可作为矩阵位移法原理教学之外的一种实践补充,与教材紧密配套,切入方便快捷,以较低的门槛,引领学生初窥有限元。