遗留桩坑对临近复合筒型基础倾斜率的影响

针对某海上风电项目,基于ABAQUS三维数值软件定量分析桩坑与复合筒型基础的距离、桩坑尺寸及深度等参数变化对复合筒型基础结构泥面倾斜率的影响,引入可反映桩坑充盈固结程度的系数γ与切线斜率K。结果表明：随着桩坑尺寸增加,复合筒型基础泥面倾斜率呈非线性增长,且均向桩坑所在方向倾斜;桩坑深度大于复合筒型基础入土深度时,基础倾斜率增长较快;研究表明筒型基础泥面倾斜率对大深度、近距离桩坑内部土体强度尤为敏感,拟通过该文研究为复合筒型基础风电机组安装船舶选型及布置提供理论依据。     

特大型洞室过浅埋段的开挖与支护

泸定水电站2号泄洪洞为特大断面洞室,具有开挖断面大、跨度宽、地质条件复杂等特点,特别是浑水沟段垂直埋深小(最小岩层埋深为6 m).根据地质勘探资料及现场地表勘查情况,通过对该段采用地表处理与洞室内处理相结合的手段,顺利完成了该洞室的开挖、支护,确保了洞室按期过流,为工程顺利进行奠定了良好的基础.     

VSMS系统在潮滩水沙测量中的应用

介绍了同步多点观测潮滩水流悬沙浓度、流速和水深和的计算机测量系统（VSMS）的组成，现场测试表明，该测系统精度较高、性能良好。     

Model of slice-push cutting forces of stacked thin material

Adding slicing to push cutting processes can significantly reduce cutting forces. Creating an appropriate model for the calculation of forces is necessary to completely understand manufacturing processes. In this investigation, a model detailing the cutting forces of stacked thin material using an asymmetrical knife is developed. Equilibrium of forces and frictional effects at the cutting edge are analyzed to determine the components in vertical and horizontal direction of the total cutting force, and their dependency on the slice-push ratio. The friction effects of the new model are based on Coulomb friction. For comparison purposes, an existing shear friction model is extended to discuss the new presented Coulomb friction model. To support the findings, the newly developed model is experimentally verified.     

Complementary tribometers for the analysis of contact phenomena in grinding

The characterization of friction and tribological phenomena occurring in grinding requires reliable experimental input data. Up to now, existing test benches exhibit important limitations. Steep thermal gradients and elastic deformations of both machine structure, and rubbing elements are the main sources of inaccuracy cited in the literature. In this paper, an alternative approach is presented for the study and characterization of contact phenomena in grinding. It consists of two complementary test benches: the On-Machine Test Bench and the High Speed Tribometer. They are designed to overcome the limitations of current grinding experimental studies.On the one hand, the On-Machine Test Bench enables accurate control of process parameters. This allows assessing the effect of the different grinding mechanisms on process forces, and specific energy. In addition, its configuration avoids steep thermal gradients; consequently, it is possible to obtain stable and accurate temperature measurements that can be directly related to process variables. On the other hand, the High Speed Tribometer enables to isolate adhesive effect because of its predominance. This test bench allows an accurate control of contact pressure and contact area. Then, adhesive phenomena can be characterized and related to process parameters using force and temperature measurements.Experimental results obtained in both test benches are presented. A wide range of data (forces, specific energy, temperatures, wear…) concerning contact conditions in grinding can be obtained from this complementary approach.     

Adhesion phenomena in the secondary shear zone in turning of austenitic stainless steel and carbon steel

This paper aims to increase the understanding of the adhesion between chip and tool rake face by studying the initial material transfer to the tool during orthogonal machining at 150 m/min. Two types of work material were tested, an austenitic stainless steel, 316L, and a carbon steel, UHB 11. The tools used were cemented carbide inserts coated with hard ceramic coatings. Two different CVD coatings, TiN and Al₂O₃, produced with two different surface roughnesses, polished and rough, were tested. The influences of both tool surface topography and chemistry on the adhesion phenomena in the secondary shear zone were thus evaluated. Extensive surface analyses of the inserts after cutting were made using techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM). As expected, cutting in the stainless steel resulted in a higher amount of adhered material, compared to cutting in the carbon steel. Remnants of built-up layers were found on the surfaces of the 316L chips but not on the UHB 11 chips. Moreover, it was shown that for both materials the tool roughness had a profound effect, with the rougher surfaces comprising much higher amounts of adhered material than the polished ones. Non-metallic inclusions from both types of workpiece steels accumulate in the high temperature area on the inserts. The general tendency was that higher amounts of transferred material were found on the TiN coating than on the Al₂O₃ coating after cutting.     

基于混合遗传算法的数控铣削参数多目标优化

针对数控程序编写以及数控仿真时切削参数的优化问题,根据最优化思想,构建数控铣削加工的数学模型,应用遗传算法与模拟退火算法相结合的混合遗传算法及MATLAB工具对切削参数进行优化,并用实验验证其对提高数控机床加工效率和降低加工成本的可行性。     

基于BP网络的非圆截面切削力补偿情况的研究

非圆截面车削加工过程中,切削力的补偿情况辨识是非常重要的。通过对非圆截面零件加工过程中切削力的测量及记录,采用BP网络模型,通过对切削力的分析和计算机系统对切削力数据进行的相关处理进而确定该过程中动态切削力的补偿情况,为切削力补偿情况辨识提供方法与依据。     

乌努格吐山铜钼矿冻土层爆破设计方案

乌努格吐山铜钼矿冬季气温常在-30~-40℃左右,持续时间长达五个月。冬季开采爆破时,上部冻土层易产生大块,影响铲装效率,造成安全隐患;在矿石区块度过大,易造成选矿厂粗碎站堵仓,增加旋回破碎机的故障率,严重时甚至会造成停产。文章根据乌努格吐山冻土层特点,进行了爆破漏斗实验和冬季冻土层爆破参数方案设计,并对所取得的经济效益进行了简要分析。     

董家河煤矿大采深条件下底板破坏深度的实测与模拟分析

 底板突水是我国煤矿的重大灾害之一。采用钻孔声波测试法对澄合矿区董家河煤矿5号煤层22507工作面进行了底板破坏深度现场监测。监测结果表明：煤体下工作面正下方的底板破坏深度最大值为10.8m,同时采用FLAC3D有限差分程序,对董家河煤矿5号煤层22507工作面采场下开采顶底板破坏效应进行了模拟研究,数值模拟结果与现场实测结果相吻合,为今后董家河及类似矿井带压开采有效隔水层厚度选取和安全开采提供技术参考。