隧道砂卵石围岩超前小导管注浆参数优化研究

隧道砂卵石围岩具有结构松散、级配分布不均匀,透水性强的特点,在进行注浆加固地层时,应合理确定注浆参数。以甘肃省渭武高速白鹤桥隧道为工程依托,结合砂卵石地层的特点,针对单水泥浆浆液易析水、水泥颗粒易沉降、凝结时间难控制、结石体易收缩、注浆压力及小导管间距难确定等问题,通过室内注浆材料试验、改性普通硅酸盐水泥性能试验及注浆模型试验对注浆加固参数进行优化设计,并提出相应的注浆控制标准。研究结果表明,最优注浆参数为:水灰比为1∶1;水玻璃波美度为38Be′,用量为3%;悬浮剂用量为1.4%;注浆压力取0.2 MPa;注浆小导管间距取30 cm。     

富水复杂地质围岩稳定性评价与支护系统优化

研究目的:富水复杂地质隧道施工过程中,不良地质带受水-岩相互作用的影响,开挖过程中拱顶、拱腰等部位极易产生块体失稳,且隧底压力经常大于垂直地压,造成仰拱断裂、边墙下部内移错动甚至衬砌失稳破坏,从而给隧道施工造成很大的安全隐患,因此很有必要对围岩稳定性进行评价,并以此为基础对围岩支护系统进行优化探讨.研究结论:(1)隧道在弱风化的花岗岩中掘进时应尽快施作仰拱,使衬砌闭合成环;(2)CD法开挖段仰拱紧跟、衬砌尽早封闭成环很有必要;(3)文兴隧道与水库之间具有水力联系的可能性,对于隧道内的渗、涌水应及时采集水样进行必要的水化学及同位素分析,判断隧道内渗、涌水的来源.(4)隧道在断层破碎带的软弱围岩中掘进时,应尽早施做二次衬砌,必要时做专项的抗水压复合式衬砌设计;(5)一旦证实水库水与隧道之间存在水力连通,隧道的断层破碎带为力学和形变不良段,车行横洞应尽量避开该位置,适宜前移或后移数十米至微风化岩层段内.     

桂林市城北水厂取水工程施工方案优化

文章以桂林市城北水厂取水工程施工为例,介绍充分利用施工现场地形、地质、水文等自然条件,优化施工方案,降低施工成本的经验.     

收费道路均衡配流的双层规划模型分析

考虑弹性用户需求下,当两点之间的收费额增加时,阻抗会随之增加,交通需求量会相应减少,引入新的交通阻抗函数。根据弹性交通需求下交通均衡配流,考虑一个双层规划模型来考虑道路经营者收费道路费率制定,同时在这个基础上给出了基于遗传一模拟退火的混合优化算法（GASA）求解算法,最后通过一个数值算例加以简单的论证,得到比较合理的费率。     

城市公共交通中的公交输送能力问题探讨

本文通过对城市交通现状的分析,指出发展城市公共交通的必要性,针对公交运行中的问题,引出了公交输送能力这一考查指标,并建立了公交输送能力模型。最后以中关村大街人民大学站为例进行了定量分析,提出如何用公交输送能力来明确公共交通中出现的问题,对研究公交线路和车辆的优化配置提供了理论依据。     

A reverse causal-effect modeling approach for signal control of an oversaturated intersection

A novel approach is presented in which signalized intersections are treated as normal highway bottlenecks for improved computational efficiency. It is unique in two ways. First, it treats the signalized intersections as common freeway bottlenecks by a reversed cause and effect modeling approach. Both traffic arrivals and departures are modeled by smooth continuous functions of time as if there were no interruptions to traffic flows from signals. The use of smooth continuous functions for departure curves instead of commonly used step functions makes it easy to apply differential calculus in optimization and future extension to a system of intersections. Second, a dynamic linear programming (LP) model is then developed to maximize the total vehicular output from the intersection during the entire period of congestion subject to prevailing capacity and other operational constraints. The continuous optimal departure flow rate (the effect) is then converted to signal timing parameters (the cause) that can be readily implemented. Two numerical examples are presented to demonstrate the properties of the proposed algorithm and examine its performance.     

浅谈网络计划的工期-成本优化在公路工程管理中的应用

介绍网络计划中的工期、成本优化及在公路工程管理中的应用.     

Parallel Distributed Implementation of Truss Optimization on a Local Area Network

A two-level optimization method for the design of complex truss and parallel distributed implementation on a LAN is presented using parallel virtual machine (PVM) for Win 32 as message passing between PCs. The volumes of truss are minimized by decomposing the original optimization problem into a number of bar optimization problems executed concurrently and a coordinate optimization problem, subject to constraints on nodal displacements, and stresses, buckling and crippling of bars, etc. The system sensitivity analysis that derives the partial derivatives of displacements and stresses with respect to areas are also performed in parallel so as to shorten the analysis time. The convergence and the speedup performances as well as parallel computing efficiency of the method are investigated by the optimization examples of a 52-bar planar truss and a 3 126-bar three-diraensional truss. The results show that the ideal speedup is obtained in the cases of 2 PCs for the 3 126-bar space truss optimization, while no speedup is observed for the 52-bar truss. It is concluded that (1) the parallel distributed algorithm proposed is efficient on the PC-based LAN for the coarsegrained large optimization problem; (2) to get a high speedup, the problem granularity should match with the network granularity;and (3) the larger the problem size is, the higher the parallel efficiency is.     

船体结构耐撞性优化设计方法研究

提出了一种船体结构耐撞性设计的优化方法,它是在试验设计、径向基神经网络和遗传算法的基础上发展而成的,用高精度的快速分析模块来代替计算量很大的复杂模型,且能处理混合离散变量和工程约束条件。为表征船体结构的耐撞性能,本文引入了耐撞指标的概念。应用上述优化方法对某散货船舷侧结构进行了耐撞性优化设计。优化过程中以耐撞指标作为目标函数,以结构重量作为约束条件,用非线性有限元动态响应分析程序ＭＳＣ／ＤＹＴＲＡ     

汽车覆盖件冲压方向优化系统设计

通过分析影响汽车覆盖件冲压方向选择的因素,建立了以评价函数法为基础的冲压方向优化模型。利用该模型对冲压件截面形状进行了分析,确定了截面转角的公共可行域,并建立了一组目标函数作为优化对象。在公共可行域内优化各个截面的转角,然后加权平均可得到目标函数的最优值。以典型汽车覆盖件为例,对实现覆盖件冲压方向的优化系统进行了理论验证。