富水砂层深基坑施工诱发邻近建筑物变形研究

依托南通市环西文化广场站项目,在围护结构施工阶段、基坑降水阶段、基坑开挖阶段采取一系列措施,减少深基坑施工对周边重要建（构）筑物的影响,项目影响电视塔的工程全部施工完成后,电视塔倾斜和沉降均在规范允许范围内。     

混凝土超声波层析成像的图像后处理方法

由于反演问题固有的不适定性以及测试和计算误差等原因,混凝土超声波层析图像中存在噪音和伪像。为了增强混凝土层析成像图像结果的信噪比,可靠辨识混凝土的内部缺陷,采用二维中值滤波和基于SOFM神经网络的聚类分析对反演结果进行图像后处理。应用实例表明,联合运用中值滤波和聚类分析的图像后处理方法,可以在局部连通和非局部非连通的区域内抑制噪音,明显改善反演图像的分辨率,有效提高缺陷识别的正确性和可靠性。     

Ultimate end bearing capacity of rock-socketed pile based on generalized nonlinear unified strength criterion

In order to study the mechanism of bearing behavior at the tip of a pile embedded in rock, the generalized nonlinear unified strength criterion and slip line principle for resolving the differential equation systems which govern the stress field were applied to derive the ultimate end bearing capacity based on some reasonable hypothesis and failure plane model. Both numerical simulation and test results were compared with the theoretic solution. The results show good consistency with each other and verify the validity of the present approach. The depth effect with respective to embedment ratio and other influence factors like geological strength index, intermediate principal stress, overburden factor, and damage on end bearing capacity were discussed in the analytical solution. The results show that the proposed yield criterion can be much better for investigating the ultimate end bearing performance of rock-socketed pile. The end bearing capacity increases with embedment ratio and the increasing degree is influenced intensely by the above parameters. Furthermore, ignoring intermediate stress effect would underestimate the strength properties of the rock material and lead to a very conservative estimation value.     

Numerical evaluation of uplifting effect for upper structure by grouting

A stratum grouting-soil-structure interaction model which simplified the grouted zone into a series of spherical grout bulbs was established using FLAC^3D program. The hypothetical non-uniform expansion process to reach an assigned volume strain due to soil compression by grouting was achieved by imposing radial velocity on outer mesh nodes of these spheres. This new method avoids the repeated trial calculation needed in the traditional method which applied a fictitious expanding pressure in the grouting element. The deformation and additional internal forces of structure were investigated during each grouting strategy and the influences of various stiffness of grouting proof curtain and bearing capacity of pile tip were discussed simultaneously. The numerical model is proved to be effective to replicate general behavior expected in the field and is capable of modeling the uplifting effect for the surface structure by grouting.     

基于工序交验和履约评价的公路建设项目网格化协同管理新模式研究

项目管理模式对于项目顺利高效地完成有着至关重要的作用,但是大多数模式只强调了以工序交验为基础的按照质量、进度、费用等一条或多条主线管理的方式,这种模式难以做到全方位把握项目进展。因此,根据协同管理的相关理念和实现思路,结合现有的基于合同的组织关系,将施工阶段以工序为基点进行分段,提出了一种基于工序交验和合同履约评价的公路建设项目网格化协同管理模式,介绍了其中绩效评价的方法。利用施工合同以计量为关键节点,以桥梁桩基施工为例进行了具体分析和讨论,为以后项目管理平台、区块链技术等的创新性发展提供相应理念。     

水平受荷桩的非线性无网格法分析

首先利用移动最小二乘近似得到求解域内的全局近似函数,再采用迦辽金法对控制方程离散,以获得无网格迦辽金方法的基本计算方程,并考虑到基桩承受水平荷载过程中的挠曲变形,探讨了无网格法在大变形问题中的具体实现;最后以湖南益阳茅草街大桥的水平静载荷试验为工程背景,采用本文理论编制考虑非线性大变形的无网格法计算程序对其进行分析。计算结果与现场实测数据吻合良好,验证了该方法的合理性与有效性,并指出桩周土体的强度和软化对基桩水平承载力的影响很大,可供工程参考。     

最优实验设计的改进随机进化算法

详细阐述构造最优实验设计的原始随机进化算法,并在原始算法的基础上,拓展广度搜索,改进深度搜索,以提高最优实验设计的计算速度。通过不同规模和不同优化准则的拉丁超立方体最优实验设计,验证改进算法的应用效果。算例分析表明,改进算法能够比原始算法节省约30%～60%的机时完成最优实验设计,而且改进算法对应于优化准则的最优值与原始算法最优值的差别仅为1%～3%。可见,改进算法能够兼顾最优实验设计的计算时间和优化质量,明显提高最优实验设计的构造效率。     

结构屈曲分析中的改进弧长控制法

本文对结构屈曲问题进行了几何非线性有限元分析,采用改进了弧长约束方程的弧长控制法求解非线性方程组,用以处理屈曲时载荷下降的问题,并通过算例,说明算法和程序的正确性和有效性.     

政府规划机构站点(一)

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