垂直预应力锚杆式水泥土墙支护受力分析计算

对垂直预应力锚杆式水泥土墙支护体系的优点和构造进行了介绍,并通过对该支护体系的研究分析,建立了受力计算模型,提出了垂直预应力锚杆式水泥土墙支护结构的计算方法,以指导实践。     

深层搅拌水泥土墙基坑支护的应用与分析

根据JGJ120-99《建筑基坑支护技术规程》对深层搅拌水泥土墙设计和施工的要求,从工程实际出发,围绕水泥土墙支护结构的整个施工过程,阐述了水泥土墙基坑支护的设计要点、力学分析、工艺方法、技术要求、效果分析等内容。     

软土深基坑TRD工法型钢水泥土墙支护结构的承载性能研究

TRD工法型钢水泥土墙在开挖深度小于10m的软土深基坑中能够身兼挡土和止水作用,与传统的SMW工法相比有显著的技术和经济优势。如同其他水泥土搅拌工艺,TRD工法形成的水泥土墙也存在极强的空间不均匀性,这必然会影响型钢水泥土墙支护结构的承载性能,但既有文献鲜有涉及。鉴于此,总结分析了现场TRD工法水泥土墙内强度分布规律,并基于随机有限元方法,重点揭示了水泥土强度空间变异性对型钢水泥土墙支护结构承载性能的影响规律。结果表明:水泥土材料参数空间变异性对TRD工法型钢水泥土连续墙的承载性能影响较为明显,在设计中应该予以充分重视;控制现场施工质量、尽量降低搅拌不均匀性,是提高软土深基坑TRD工法型钢水泥土墙支护结构承载性能的有效措施之一。     

深基坑水泥土墙的应用分析

深基坑支护结构形式和设计计算的方法很多,如何合理选取是值得研究的问题.结合工程实例,根据水泥土墙的特点,以及工程地质条件和周围环境,对基坑开挖进行了可行性和稳定性分析,并对水泥土墙在工程中的应用进行了探讨,供相关工程参考.     

水泥土桩墙支护结构的优化设计

水泥土桩墙支护结构常规的设计方法采用试算校核法,此方法不仅计算繁琐,而且难以得到既经济又可靠的设计方案.为此,本文探讨了水泥土桩墙支护结构参数的优化设计,建立了相应的以水泥土桩墙的有效宽度、埋入深度和置换率为决策变量的优化设计模型,并引用遗传算法对优化模型求解.最后给出了工程计算实例,计算结果表明此优化方法是可行的.     

水泥土墙支护结构设计与施工

结合具体工程实例 ,从施工工艺流程、技术要求、工艺参数及施工等方面介绍了水泥土墙格栅式支护结构的设计与施工 ,经实践证明 ,该方法施工速度快 ,经济合理 ,安全可靠 ,取得了良好的效果。     

某重力式水泥土墙基坑支护工程实践

本文介绍了重力式水泥土墙支护结构的应用现状、主要特点、设计要点等。通过某一实际工程的成功实践,表明在特定土层(如填土层、砂层、淤泥等)、基坑平面较大的单层基坑工程中,重力式水泥土墙支护结构是经济合理且安全可靠的支护结构类型之一,值得类似工程借鉴。     

水泥土墙复合支护方案的应用

针对兴化市供电公司生产调度综合楼基坑支护工程的特点,结合场地地质条件和场地环境,分别采用格栅式水泥土墙支护和水泥土桩防渗、放坡开挖的复合支护方案进行处理,既保护了周围环境,又节省了工程造价。在提出支护处理方案的基础上,侧重论述水泥土墙复合支护结构的设计施工要点和质量控制。     

湖南某办公大楼深基坑水泥土墙设计及分析

湖南某办公楼在复杂地质条件下深基坑水泥土墙的设计,并就水泥土墙的稳定、倾覆、滑移进行了验算,对不同的土层压力计算的结果进行了深入细致的分析,并得出了相关结论,对同类型支护形式的设计具有指导作用。     

水泥土墙支护结构计算实例

采用深层搅拌水泥土桩墙作基坑的支护结构,具有挡土、挡水双重功能。本文按照《建筑基坑支护技术规程》（JGJ120—99）的规定,介绍水泥土墙支护结构的计算方法。     

基于遗传算法的密肋复合墙体多目标优化设计方法研究

密肋复合墙体是密肋壁板结构体系的主要受力构件,墙体的优化设计方法研究是结构体系设计理论的重要组成部分。在前期研究的基础上,建立综合考虑密肋复合墙体安全性(墙体斜截面抗剪承载力)与经济性(墙体造价)的多目标优化设计数学模型,并采用遗传算法进行优化计算,最后给出了计算算例。理论分析与计算结果表明:将多目标优化设计方法用于密肋复合墙体的优化设计中,可使各个分目标都较为满意,兼顾了墙体安全性与经济性两方面的要求;方法合理、可行,对密肋复合墙体的设计有一定参考意义。     

Novel decoupled framework for reliability-based design optimization of structures using a robust shifting technique

In a reliability-based design optimization (RBDO), computation of the failure probability (P_f) at all design points through the process may suitably be avoided at the early stages. Thus, to reduce extensive computations of RBDO, one could decouple the optimization and reliability analysis. The present work proposes a new methodology for such a decoupled approach that separates optimization and reliability analysis into two procedures which significantly improve the computational efficiency of the RBDO. This technique is based on the probabilistic sensitivity approach (PSA) on the shifted probability density function. Stochastic variables are separated into two groups of desired and non-desired variables. The three-phase procedure may be summarized as: Phase 1, apply deterministic design optimization based on mean values of random variables; Phase 2, move designs toward a reliable space using PSA and finding a primary reliable optimum point; Phase 3, applying an intelligent self-adaptive procedure based on cubic B-spline interpolation functions until the targeted failure probability is reached. An improved response surface method is used for computation of failure probability. The proposed RBDO approach could significantly reduce the number of analyses required to less than 10% of conventional methods. The computational efficacy of this approach is demonstrated by solving four benchmark truss design problems published in the structural optimization literature.     

基于连续体结构拓扑优化的树状结构拓扑创构

针对概念设计阶段树状结构拓扑创构问题,提出了连续体结构拓扑优化方法。应用连续体结构拓扑优化法,建立体积约束下结构总应变能极小化（即结构总体刚度极大化）的拓扑优化模型,依据单约束优化问题的鞍点条件建立了优化迭代格式。研究了体积比、屋面结构刚度、屋面结构几何形式、设计空间高度等对树状结构拓扑形态的影响,并给出了具体应用算例。结果表明：随着材料用量的增加,树状结构拓扑随之复杂;随着屋面刚度的增加,树状结构分枝趋向于减少;不同的屋面结构几何形式会导致不同的树状结构拓扑形态;满足一定高度后,树状结构分枝形态不会受高度影响,仅是增加主树杆高度。     

基于模糊可靠性分析的碟形弹簧优化

运用模糊可靠性设计理论和优化设计技术,提出了基于模糊可靠性分析的碟形弹簧的优化方法．该方法能同时考虑到碟形弹簧各设计参数的离散性和设计边界的模糊性,因而设计出的碟形弹簧经济、合理、适用．     

自平衡法在某工程中的应用

介绍了桩承载力自平衡测试基本原理,根据在工程实践中的应用,总结了该测试方法的优点,同时优化了设计,节约了成本,并为后期桩基设计与施工的优化提供了可靠参数。     

考虑预应力实施过程的预应力钢结构全过程优化设计

分析预应力实施过程对优化设计结果的影响,探讨预应力钢结构的全过程优化设计概念。在对预应力实施过程进行统一描述的基础上,建立预应力钢结构的全过程优化设计数学模型,并从索初始形变的角度出发,基于预应力钢结构的施工力学分析理论,探讨全过程分析的优化模型约束条件计算方法。最后,依据分级优化思想,将优化模型中的设计变量分为若干层次,构建优化模型求解的三级优化方法。算例结果表明,全过程优化设计方法具有较高的效率与良好的稳定性,能够考虑不同的预应力实施过程对优化结果的影响。如给定各次预应力阶段的张拉批次顺序,可同时输出相应的预应力阶段张拉控制力方案,从而实现结构设计方案与预应力实施方案的整体优化。     

Shape design of arch dams under load uncertainties with robust optimization

Due to an increased need in hydro-electricity, water storage, and flood protection, it is assumed that a series of new dams will be build throughout the world. The focus of this paper is on the non-probabilistic-based design of new arch-type dams by applying means of robust design optimization (RDO). This type of optimization takes into account uncertainties in the loads and in the material properties of the structure. As classical procedures of probabilistic-based optimization under uncertainties, such as RDO and reliability-based design optimization (RBDO), are in general computationally expensive and rely on estimates of the system’s response variance, we will not follow a full-probabilistic approach but work with predefined confidence levels. This leads to a bi-level optimization program where the volume of the dam is optimized under the worst combination of the uncertain parameters. As a result, robust and reliable designs are obtained and the result is independent from any assumptions on stochastic properties of the random variables in the model. The optimization of an arch-type dam is realized here by a robust optimization method under load uncertainty, where hydraulic and thermal loads are considered. The load uncertainty is modeled as an ellipsoidal expression. Comparing with any traditional deterministic optimization method, which only concerns the minimum objective value and offers a solution candidate close to limit-states, the RDO method provides a robust solution against uncertainty. To reduce the computational cost, a ranking strategy and an approximation model are further involved to do a preliminary screening. By this means, the robust design can generate an improved arch dam structure that ensures both safety and serviceability during its lifetime.     

城市地铁区间隧道监控技术与分析

结合深圳地铁3号线区间隧道施工实际,论述了地铁隧道结构位移、沉降的监控量测方案设计与实施方法,提出了具体合理的监测措施和预报流程,实践证明监测效果可靠,为保证该隧道的顺利贯通提供了可靠的技术保证。     

Topology optimization method of lattice structures based on a genetic algorithm

A two-stage topology optimization method of lattice structures based on a genetic algorithm is proposed. The first stage is the form-finding analysis of lattice structures, and the optimal initial shape was achieved with the numerical inverse hanging method. The second stage is the topology optimization of single-layer lattice structures, which can be realized by changing the mesh size and the tube configurations to minimize the total weight of steel tubes subject to the design requirements. The mesh configuration optimization is realized through the adjustment of the nodal horizontal co-ordinates and the removal of tubes with lower stress. The maximum displacement of the structure, the maximum stress of the circular steel tubes, and the nonlinear buckling load are the state variables, and a genetic algorithm (GA) is the optimization algorithm. Different stress-limiting values used to delete the tubes were discussed. The numerical examples show that the two-stage topology optimization method for lattice structures proposed in this paper is correct and efficient. Furthermore, the forms of the optimized structure are rich, and the structure is lightweight and efficient.     

Global optimization of a central air-conditioning system using decomposition-coordination method

The global optimization model for the overall control of air-conditioning system aiming at the minimum energy consumption is developed in this work. The method of decomposition-coordination, which is adept at solving the ultrahigh-dimensional optimization problems, is used for the model solution. Taking one real central air-conditioning system as the case study, the hourly optimal conditions of all equipments in this system on one operation day were simulated by the global optimization model. To examine the validity of decomposition-coordination algorithm, direct-search method (which is admitted to be the most reliable in optimization calculation) is used to make the comparison. It showed that the optimal results obtained by the two methods were essentially the same, but decomposition-coordination method would have much higher calculation efficiency than direct-search method. The energy analysis indicated that the energy saving brought by the global optimization was mainly thanks to the adjustment of pumps and fans rather than that of the chillers. It was believed as well that more energy saving would be achieved under the lower load condition of the system if the globally optimal control scheme were implemented.