Experimental and Theoretical Study on the Self-Weight Penetration Velocity of Suction Anchor Foundations in Sand

The application of the wellhead suction anchor in the second production test of natural gas hydrates(NGHs)in the South China Sea(SCS)was met with success.This design incorporates a central conductor guide pipe,which distinguishes it from traditional suction foundations.However,this addition resulted in a relatively high penetration resistance and a shallower penetration depth at the self-weight penetration stage.To mitigate this issue,the current study proposes an optimized design where the end of the suction foundation is sharpened.The installation characteristics of the traditional suction foundation and new suction foundation during self-weight penetration into sand are studied through laboratory tests and theoretical analysis.The flat and sharpened bottom shapes are considered in the traditional and new suction models.The effects of the initial penetration velocity on the initial penetration depth and soil plug and impact cavity characteristics are systematically studied.The results show that the self-weight penetration depth of the foundation with a sharpened bottom is 44.5%deeper than that of the foundation with a flat bottom.There are cavities around the foundation at the self-weight penetration stage,and the penetration depth is overestimated by 15%-30%.Finally,a model for predicting the penetration depth of the new suction foundation is proposed.

半刚性节点网壳结构研究进展及关键问题

装配式节点通常采用单根或多根螺栓与构件连接,往往具有一定的半刚性特性。但目前,由于对装配式节点认识不足,在装配式网壳结构分析和设计时,通常假定其节点连接为铰接;然而,通过研究发现实际装配式节点具有较好的半刚性性能;为适应实际工程所研发的新型装配式半刚性节点具有刚度更大、更加高效等优点,可应用于更大跨度的单层网壳结构中。半刚性节点网壳结构具有广阔的应用前景,针对半刚性节点及其网壳性能的研究逐渐成为建筑结构领域的热点研究课题之一。该文综述了国内外半刚性节点及半刚性节点单层网壳结构的现有研究成果以及尚需深入研究的主要问题。文献分析表明,目前针对半刚性节点及半刚性节点网壳结构静力性能的研究已取得一定的成果。然而,关于空间半刚性节点在复杂荷载作用下节点抗弯性能、空间半刚性节点耗能性能、适用于更大跨度的新型空间节点研发、半刚性节点网壳结构动力稳定性等方面有必要进行更多更深入的试验和理论研究,以推动半刚性节点单层网壳结构的实际工程应用。

空压机余热回收制冷工艺可行性分析

根据典型工程的咨询案例对空压机余热回收吸收制冷工艺进行可行性分析。利用Aspen Hysys软件计算空气压缩过程的热量生成量,通过市场调研和咨询方式确定当前主流吸收制冷设备厂家,确定吸收制冷系数和投资规模。结合空压机的运行工况和当地供冷供热需求,从技术可行性和投资回收期两方面对空压机余热回收吸收制冷工艺进行可行性分析。结果显示:离心式空压机余热回收技术具备可行性,可以生成95℃热水,配套吸收制冷工艺可以制成12℃冷水;基于所选设备的投资平均回收期为7.8个月。

大学生公益活动浅谈

最近几年,随着公民意识的觉醒,各种NGO(非政府组织)、NPO(非盈利组织)组织如雨后春笋般涌现,在我们的社会发展中,公益组织起到了越来越重要的作用。越来越多的普通公民选择加入各种志愿者组织,进行各种志愿者服务,回馈社会,获取个人精神层面的满足。大学生通过成立各种公益社团,来服务于社会。大学生热衷于社会公益实践是一件好事情,但是目前大学生的公益社团存在着各种各样的问题,比如:活动形式单一,影响力不足;社团领导人综合素质不全面;公益性社团缺乏信任度等[1]。本文通过探讨大学生公益活动存在的一些问题,帮助大学生更好的进行公益活动。

Self-Weight Penetration Characteristics of the Suction Foundation with Different Diameters in Sand

During the self-weight penetration process of the suction foundation on the dense sand seabed,due to the shallow penetration depth,the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure.Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation.The new suction anchor foundation has been proposed,and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis.For the above two foundation types,by considering five foundation diameters and two bottom shapes,20 models are tested with the same penetration energy.The effects of different foundation diameters on the penetration depth,the soil plug characteristics,and the surrounding sand layer are studied.The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation.With the same penetration energy,the penetration depth of the suction foundation becomes shallower as the diameter increases.The smaller the diameter of the suction foundation,the more likely it is to be fully plugged,and the smaller the height of the soil plug will be.In the stage of self-weight penetration,the impact cavity appears around the foundation,which may affect the stability of the suction foundation.