The design of universal segments and deviation control of segment assembly are essential for robust and low-risk tunnel construction.A building information modeling(BIM)-based framework was proposed for parametric mod...The design of universal segments and deviation control of segment assembly are essential for robust and low-risk tunnel construction.A building information modeling(BIM)-based framework was proposed for parametric modeling,automatic assembly,and deviation control of universal segments.First,segment models of different levels of detail(LoDs)were built based on BIM visual programming language(VPL)for different project life cycles.Then,the geometric constraints,requirements,and procedures for parametric segment assembly were distilled to develop a program that combines a novel typesetting algorithm with a 3D path replanning algorithm.Typesetting is implemented by introducing a point indication matrix,characterizing segments by sides,and manipulating geometries in a VPL.Simultaneously,3D path replanning,with non-uniform rational B-splines(NURBS)and arcs as basic shapes,was used to resolve unacceptable deviation situations after typesetting.Finally,the proposed framework was validated on a water diversion line and was found to be more effective and accurate than the previous method.展开更多
文摘为研究不同差分码偏差(differential code bias,DCB)产品对BDS-3伪距单点定位的影响,推导了BDS-3单频和双频无电离层组合伪距单点定位卫星端DCB改正模型,基于多模全球导航卫星系统(global navigation satellite system,GNSS)实验跟踪网发布的中国科学院(Chinese Academy of Sciences,CAS)和德国宇航中心(Deutsches Zentrum für Luftund Raumfahrt,DLR)两种DCB产品,并结合全球不同纬度均匀分布的国际GNSS服务测站连续7天的BDS-3实测数据对B1I、B1C和B2a单频与B1C/B2a、B1I/B3I两种常用无电离层组合伪距单点定位精度进行对比分析。实验结果表明,在B1I、B1C、B2a 3种频率和B1C/B2a、B1I/B3I两种组合中,CAS产品改正后的定位精度整体上优于DLR产品,具体来说,定位精度的平均值在E、N、U 3个方向上分别提高了3 cm、1 cm和6 cm。
文摘The design of universal segments and deviation control of segment assembly are essential for robust and low-risk tunnel construction.A building information modeling(BIM)-based framework was proposed for parametric modeling,automatic assembly,and deviation control of universal segments.First,segment models of different levels of detail(LoDs)were built based on BIM visual programming language(VPL)for different project life cycles.Then,the geometric constraints,requirements,and procedures for parametric segment assembly were distilled to develop a program that combines a novel typesetting algorithm with a 3D path replanning algorithm.Typesetting is implemented by introducing a point indication matrix,characterizing segments by sides,and manipulating geometries in a VPL.Simultaneously,3D path replanning,with non-uniform rational B-splines(NURBS)and arcs as basic shapes,was used to resolve unacceptable deviation situations after typesetting.Finally,the proposed framework was validated on a water diversion line and was found to be more effective and accurate than the previous method.
