New analysis method of seismic passive earth pressure and its distribution on a retaining wallEI北大核心

Research purposes: At present, the analysis methods about seismic passive earth pressure and its distribution have several defects, including unreasonable distribution rule and position, complex derivation, harsh application conditions and so on. The seismic passive earth pressure problem is translated into non-seismic passive earth pressure problem in this paper by using the transform method with rotating calculation model of retaining wall. This method has large reference value to simplify the calculation process of seismic passive earth pressure and its distribution. Research conclusions: Based on the non-seismic passive earth pressure formulations with horizontal slices analysis method, the analytical formulas of seismic passive earth pressure intensity distribution, resultant force of earth pressure and its point position are obtained directly, and the explicit solution of critical rupture angle is got by graphic method. The influencing factors including horizontal and vertical seismic accelerations, different angle of wall back, cohesion and external friction angle between filler and back of retaining wall, equispaced overloading are considered. The formulas can be used for seismic passive earth pressure calculations of cohesive soil with common border condition. The deducing process of seismic passive earth pressure formulations is simplified and unified greatly by using the method in this paper. The seismic passive earth pressure theory is perfected much more. The research results can be applied to do fast computation about seismic passive earth pressure of retaining wall.     

港珠澳大桥主体工程桥梁DB01标段工程地质分析

本文简要介绍了港珠澳大桥主体工程桥梁DB01标段第一合同段的地质勘察工作和成果;通过对不同桩型单桩承载力的估算与分析,提出了桥墩基础采用嵌岩桩（钢管复合桩）的建议;通过单桩承载力理论计算与试桩数据的对比,确认了提供的桩基参数是准确、可靠的。     

远洋船舶NOx排放量的测量

针对营运船舶上柴油机的实船NOx排放测量,给出了一种通过实际测量少数几个数据,便可推算出NOx排放值的方法.这样就可利用简单小型设备进行实船测试,从而使船舶柴油机的实船排放测量变得容易操作,根据其测量值判断是否符合的排放要求.     

新加坡南洋理工大学地下技术及岩土工程项目研究进展

以新加坡南洋理工大学“地下技术及岩土工程项目”为依托,总结了南洋理工大学近期在岩土工程技术与地下防护技术领域所开展的研究工作.     

舰船舵阻摇技术的研究现状及展望

综述了舵阻摇技术的产生及国内外舰船舵阻摇技术的发展现状,重点描述了各种舵阻摇控制算法,介绍了国外定型的舵阻摇产品,并对舵阻摇今后研究的重点进行了展望。     

高速公路静态交通标志设置科学性分析

针对当前中国高速公路交通标志设置中存在的一些不容忽视的问题 ,以驾驶员信息接收和加工的基本规律为基础 ,分析了驾驶员有效利用交通标志传递信息的条件 ,研究了交通标志的视认距离、在空间的安置方式、同时并设及列队连续设置等因素对静态交通标志设置的影响     

乘用车未燃碳氢化合物排放规律解析

基于乘用车汽油发动机未燃碳氢化合物排放产生机理分析,根据某型乘用车怠速HC排放实测样本数据,分析并研究了HC排放的统计规律,建立了描述这种统计规律的分布函数与分布密度函数数学模型。验证表明,利用所建数学模型得到的计算结果与样本实测结果高度吻合。在此基础上,提出了修改在用汽车排气污染物限值国家标准的具体建议,并指出应强化I／M制度以有效地控制在用汽车的排放污染。     

整车淋雨试验方法及常见漏水问题分析

整车淋雨是一项重要的质量指标,常用的分析方法有拆解覆盖件法、内窥镜检测法和注射器或高压水枪法等。整车淋雨的质量不仅关系到客户体验,部分问题可能影响整车寿命及顾客安全。故熟练掌握淋雨的原理、试验方法及常规问题的处理方法,并形成历史问题库,用于新品车型,可以从源头控制由于漏水造成的风险,提升企业的质量控制能力。     

Seabed collision emergency decision-making of AUV based on safety domain model北大核心CSCD

［Objectives］To ensure safety and prevent seabed collisions in complex unknown underwater environments, this study proposes a seabed safety domain model and tiered emergency response strategies. ［Methods］A vertical motion simulation model is established and verified by surpassing the test results, then used to calculate the active and passive safety domain distance of an autonomous underwater vehicle (AUV), thereby establishing a seabed safety domain model. An AUV emergency control system and emergency strategies are then built on the basis of the dynamic safety domain model. The trim and distance from the seabed of the AUV are used to calculate the current and future risk factors. Based on the weighted sum, the comprehensive risk factor is employed to provide the AUV with emergency response strategies.［Results］Lake tests with the AUV sailing at a fixed depth and height show a strong dependency of the comprehensive risk coefficient on seabed height when it is close to the boundary of the AUV's active safety domain. In the opposite case, there is a weak dependency of the comprehensive risk coefficient on seabed height. The results show that the proposed AUV emergency control system can reduce emergency false alarms caused by frequently changing riverbed heights and sailing altitudes close to the seabed. In such cases, reasonable emergency strategies can be realized under complex rough terrain.［Conclusions］The AUV seabed safety domain model and tiered emergency response strategies based on vertical motion equations proposed herein can be applied to evaluate seabed collision risk in various cases. Finally, this paper provides emergency response strategies to avoid seabed collision accidents, which can enhance the safety of AUV navigation. © 2023 Chinese Journal of Ship Research. All rights reserved.