非对称建筑荷载作用下小净距隧道施工模拟分析

在非对称建筑荷载作用下,采用CRD法和预留核心土弧形导坑法两种施工开挖方案,对小净距隧道的施工过程进行了数值模拟研究.对两种施工方案的洞室周边竖向变形、地中围岩变形和洞室周边的围岩应力进行了对比分析,揭示了非对称建筑荷载作用下两种方案的洞室周边竖向变形规律和变形规律的相似性,获得了地中围岩变形的变化规律,对信息化反馈施工,指出了必须重点监控与关注的位置.     

A stochastic optimization approach for the selection of reflective cracking mitigation techniques

PurposeIn Hot Mix Asphalt (HMA) overlays, the existing cracks in the underlying pavements can propagate upward to the new added overlay and may cause Reflective Cracks (RC). These cracks allow water infiltration to the underlying layers and causes further moisture damage as well as weakening the unbound layers. Over the years, several methods have been developed for mitigating the RCs. This study aims to investigate the current reflective cracking mitigation methods and develop a methodology for the selection of appropriate mitigation technique. The developed model is then applied to a case study in the state of Florida.MethodTo accomplish this goal, a nationwide literature review was conducted to better understand the current in practice methods in the United States. Moreover, a life cycle cost analysis (LCCA) in five different road types was performed to find the annuity of roadway rehabilitation for each of the mitigation methods. The uncertainty in the LCCA results is represented using Exploratory Modeling and Analysis (EMA) method. Then through a Multi Criteria Decision Making (MCDM) model, a stochastic optimization model was developed to find the appropriate reflective cracking mitigation solution under Florida’s climate and road conditions, based on different cost and performance weights.ResultsBased on the available data for the state of Florida, the LCCA results indicate that the annuity of maintaining the roadway with Fabrics and ISAC are lower compared to other methods. However, the results of stochastic optimization model reveal that while looking at the performance and cost at the same time, different methods would be more feasible. For instance, while the cost of the used method does not matter at all and only performance matters, STRATA® is more probable to be the appropriate mitigation technique. The findings of this research are critical for decision makers to better understand the most cost-effective mitigation technique in different conditions.     

水泥混凝土路面病害的预防及处理措施

随着我国公路建设的快速发展,水泥混凝土路面的铺筑越来越广泛。目前,我国各省市二级公路大部分采用水泥混凝土刚性路面,在部分省市如广西、广东,水泥混凝土刚性路面还广泛运用于高速公路。因此,水泥砼路面的质量对投资和运营至关重要。     

浅谈公路工程估算编制的新规则

新的《公路工程基本建设项目投资估算编制办法》和《公路工程估算指标》自2012年1月1日正式实施。取代1996编办和指标,针对估算编制的新规则,分析总结新旧差异,为以后估算编制工作提供指导。     

基于船舶领域和MMG的最晚施舵点/CRI研究

提出了一种基于MMG和船舶领域的LSP计算模型,以及改进的空间碰撞危险度（space collision risk index,SCRI）/时间碰撞危险度（time collision risk index,TCRI）模型,并进行了计算机仿真.结果表明：水动力模型精度可满足研究与实践要求;基于二分法的LSP模型能快速、可靠收敛;LSP和SCRI/TCRI模型更符合海员通常做法和避碰规则的公认理解.     

Structural response of a flexible pipe with damaged tensile armor wires under pure tension

This article studies the structural response of a 6.0” flexible pipe under pure tension considering intact and damaged conditions. In the damaged condition, several wires of the tensile armor layers are assumed to be broken. A three-dimensional nonlinear finite element (FE) model devoted to analyze the local mechanical response of flexible pipes is employed in this study. This model is capable of representing each tensile armor wire and, therefore, localized defects, including total rupture, may be adequately represented. Results from experimental tests validate the FE predictions and indicate a reduction in the axial stiffness of the pipe, a non-uniform redistribution of forces among the remaining intact wires of the damaged tensile armor layers and high stress concentrations in the wires near the broken ones. Moreover, the FE model indicates that significant normal bending stresses may arise in the pressure armor and inner carcass due to an uneven pressure distribution on these layers. Finally, the results obtained are employed to estimate the pull out capacity of the studied flexible pipe.     

高职《建筑材料》课程教学改革与实践

针对建筑材料课程在理论和实践课教学中存在的不足,就建筑材料理论教学和实践教学及教学方法的改革提出几点可行性建议,从而激发学生的学习兴趣,培养其创新能力,为毕业生在今后的设计和施工工作中合理选材打下坚实的基础。