基于性能的拱形抗滑桩墙支护结构体系优化设计的思考

以提供明确性能的滑坡锚碇拱形抗滑桩墙支护结构体系全局优化设计方案为目的,利用先进的基于性能的结构优化设计理念、计算机信息处理技术和智能决策技术,研究锚碇拱形抗滑桩墙支护结构的空间合理布置对结构体系受力的影响、锚碇拱形抗滑桩墙支护结构体系的数值计算方法和优化模型,探索锚碇拱形抗滑桩墙支护结构体系失效损失的评估方法和评估模型,开发基于性能的锚碇拱形抗滑桩墙支护结构体系全局优化设计软件,为滑坡治理提供明确的安全、经济、性能等参数的全局最优支护方案。对解决当前滑坡治理方案中受力体系的选择与布置、工程治理中的资源浪费和财产损失及延长使用等问题具有积极作用,是滑坡治理方面一项既有理论意义又极具应用前景的工作。     

建筑环境声学研究的进展——记第二届西太平洋地区声学会议

由英国声学学会香港分会和香港理工学院组织的第二届西太平洋地区声学会议,于1985年11月28日至30日在香港举行.我国以及其它十多个国家和地区的140人参加了会议.     

提高轻板隔墙的隔声性能

影响轻板隔墙隔声性能的因素是多方面的.本文着重研究了降低龙骨的传声、附加构造的作用以及墙板的选择等方面.文中通过理论分析和实验比较,说明这些措施对提高轻板隔墙的隔声性能是有效而可行的.     

基于Theil指数的复合土钉墙安全灰色评价

针对复合土钉墙的安全评价问题,以复合土钉墙基坑支护技术规范为依据构建了安全评价指标体系,并在运用Theil指数确定安全评价指标权重的基础上,对复合土钉墙安全进行灰色综合评价,得出安全评价等级.为复合土钉墙安全评价提供了新思路.     

MEASUREMENT OF ADHESION FORCES IN AIR WITH THE VIBRATION METHOD

The vibration method represents a practical method for the measurement of adhesion forces and adhesion force distributions. This method causes sinusoidally alternating stresses and yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an adhesion force intensification through flattening of asperities. The measuring principle of the vibration method and the analysis of experimental results are described in the article. Normal adhesion forces (pull-off forces) are measured using the vibration method and the colloidal probe technique. The results of both methods show good agreement for small particle sizes. The influence of the detachment force direction is shown by comparing tangential and normal adhesion forces measured using particle reentrainment in a turbulent air flow and the vibration method, respectively. The surface roughness of the substrate and the relative humidity are shown to significantly influence the measured adhesion forces. For the calculation of the adhesion forces, an approach by Rabinovich was combined with approximations of plastic micro asperity flattening. The Rabinovich approach accounts for roughness effects on the van der Waals force by incorporating the rms roughness of the interacting surfaces, rms-values of the particles and substrates were measured with atomic force microscopy at different scanning areas.     

提高强冲击荷载作用下平板式防护门门框墙抗力的方法

在强冲击波荷载作用下门框墙转角处会产生明显的应力集中,影响门框墙体系甚至整个防护结构的安全。为解决该问题,提出在迎爆面门框墙和衬砌结合部位设置薄弱层的构造方法,从而减小冲击荷载引起的过大的拉应力。运用考虑了剪切变形的悬臂梁理论分析表明,梁端部约束刚度的变化可以影响结构的破坏形态以及结构的内力分布,降低端部的约束刚度可以有效降低端部区域的内力峰值,延缓结构发生破坏的时间。利用有限元模拟的方法,分析了在出入口门框墙位置设置薄弱层对门框墙动力响应和破坏规律的影响。分析结果表明,设置薄弱层可以有效降低门框墙转角处的应力,降低门框墙结构破坏的风险,进而提高门框墙的抗力水平。     

桁架式钢筋混凝土叠合板式墙抗爆性能实验

为研究桁架式叠合板式墙的抗爆性能,进行了2块桁架式叠合板式墙和2块现浇板式墙在多次冲击荷载作用下的对比实验,分析了各试件的破坏过程、变形(刚度)、承载力、强度及裂缝分布形态。结果表明:桁架式叠合板式墙与现浇板式墙相比,爆炸破坏过程相似;爆炸荷载小时,试件处于弹性状态,两者刚度基本一致;开裂后,现浇板式墙比叠合板式墙刚度降低明显快,桁架钢筋能有效抑制裂缝扩展,且试件并未出现剪切破坏。说明桁架式叠合板式墙的整体性能较好,叠合板式墙的抗爆性能优于现浇板式墙。     

弹性体涂覆砌体墙抗爆炸冲击数值模拟

采用LS—DYNA动力学有限元软件对弹性体涂覆砌体墙在爆炸载荷下的响应进行了数值模拟,并研究了爆炸荷载作用下结构的应力、速度、位移的变化及破坏过程．通过比较各种涂覆方式下的响应,对该涂覆技术的有效性进行了评估．数值模拟的结果表明：采用弹性体涂覆能有效提高砌体墙的抗爆炸冲击能力．     

Boundary Layer on a Moving Wall with Suction and Injection

We investigate the boundary-layer flow on a moving permeable plate parallel to a moving stream. The governing equations are solved numerically by a finite-difference method. Dual solutions are found to exist when the plate and the free stream move in the opposite directions.     

First-principles study of the effects of selected interstitial atoms on the generalized stacking fault energies,strength, and ductility of Ni

We analyze the influences of interstitial atoms on the generalized stacking fault energy （GSFE）, strength, and ductility of Ni by first-principles calculations. Surface energies and GSFE curves are calculated for the （112） （111） and / 101） （ 1 1 1） systems. Because of the anisotropy of the single crystal, the addition of interstitials tends to promote the strength of Ni by slipping along the （10T） direction while facilitating plastic deformation by slipping along the （115） direction. There is a different impact on the mechanical behavior of Ni when the interstitials are located in the slip plane. The evaluation of the Rice criterion reveals that the addition of the interstitials H and O increases the brittleness in Ni and promotes the probability of cleavage fracture, while the addition of S and N tends to increase the ductility. Besides, P, H, and S have a negligible effect on the deformation tendency in Ni, while the tendency of partial dislocation is more prominent with the addition of N and O. The addition of interstitial atoms tends to increase the high-energy barrier γmax, thereby the second partial resulting from the dislocation tends to reside and move on to the next layer.