上海磁悬浮列车工程基岩水准标设计与施工

Design and construction of bedrock bench mark for magnetic suspension bullet train engineering in Shanghai

磁悬浮列车是当今世界上最为现代化的陆上交通工具 ,其对工程沿线地面沉降控制要求严格 ,每一跨径差异沉降须小于 3mm ,对沉降监测的测量基准点的稳定性也有严格要求。工程所在的上海浦东地区第四系厚 30 0余m ,土层固结变形明显 ,同时受抽汲地下水及工程建设影响 ,易诱发和加剧地面沉降。因此在第四纪覆盖层之下的稳定基岩体内设置测量基准 ,较之常规的地面水准点具有更高的精度要求。上海磁悬浮列车工程专门设计施工了两座基岩水准标 ,作为沉降监测的测量基准。该基岩标较以往监测标志有重大改进 ,标体结构包括保护装置、引测装置、导正装置、标底装置及地面装置 5大部分。保护装置采用较大口径的优质无缝钢管作保护管 ;引测装置采用管径与壁厚较大的钻杆 ,并以上细下粗的宝塔型异径丝扣组合方式连接 ;导正装置采用刚性扶正器 ,本体为合金铸钢、滚轮为不锈钢 ,配备轴承构件 ,扶正器安设位置与间距依材料力学纵弯曲理论计算的半波长确定 ;标底装置外焊加强筋 ,并配托盘管靴 ,灌注定量水泥 ,使其与基岩体固结成一体 ;地面装置设测点 ,并附设GPS测墩 ,兼有高程控制与平面位置控制的作用。该基岩标结构的优化改进 ,进一步提高了标体运行的稳定、可靠与长效性 ,并获国家技术专利。基岩标的现场施工 。

Magnetic suspension bullet train is modern means of communication at the present time.It is not only strict with land subsidence control along the engineering line for less than 3mm of difference subsidence of every span,but also stabilization of surveying datums mark for land subsidence monitoring.The Quaternary strata is over 300m thickness in construction site in Pudong New Area of Shanghai.These strata are obviously consolidated deformation and easily induced or enhanced the land subsidence by pumping the underground water and engineering construction.The surveying datums mark built inside the stable bedrock beneath the buried Quaternary strata is more accuracy than that of normal bench mark.As a surveying datums mark of land subsidence,the two bedrock bench marks have been exclusively built in magnetic suspension bullet train construct site.\;The bedrock bench mark have been significant improved than before.The mark is divided into 5 parts:the protecting equipment,the measure shaft,put right equipment,mark bottom equipment and ground equipment.The seamless steel tube of more big diameter and high quality is used for protecting pipe of the protecting equipment.The measure shaft is that the drill rod diameter is large and the pipe wall is thick,and linked with the sub of the pagoda whose upper is fine and bottom is big.The put right equip is rigidity and alloy cast steel,and the wheel is stainless steel.It equips the bearing components.The position and gap of put right equipment are defined by the calculated semi-wave of mechanics of materials.The mark bottom equipment is equipped with welded reinforcing steel out of it and tray boots with quantitative cement in order to consolidata with bedrock body.The ground equipment is arranged to survey spots with additional GPS measure rack,and flat surface place.The optimum improved of structure of bedrock bench mark is further enhance, the stability and reliability are long term in motion.This technology of bedrock bench mark is gain the national technology patent.\;The construction of bedrock bench marks is a key spot for object,which materializes the designed idea and guarantee the realization of purpose and action of bedrock bench marks.The hole bend degree of bedrock bench marks has high request,and hole slope is less than 0\^5° per 100m,and less than 1° after finished drilling.In drilling,the hole slope is measured every 25m,and at any time adope the effective measurements to prevent and correct the hole decline.Drilling in the clayed and sandy layers of Quaternary is Shanghai area,the mud of high quality and lower solid state is used for safe drilling.The installation of the apparatus of bedrock bench mark is the last key working procedure,and is arranged by regulations in order to guaranteeing the engineering quality.\;The total footage of two bedrock bench marks of magnetic suspension bullet train is Shanghai is 667\^83m.The depths of the two holes are 366\^43m and 301\^40m,and the two bedrock bench marks are touched the volcanic rock of Jurassic Period beneath the depth of 13\^53m and 12\^56m.The most hole slope is less than 0\^8°.Finished in Apr.2001,the bedrock bench marks are playing important role in the magnetic suspension bullet train engineering construction.\;This paper presents the designing principle,structure characteristics and construction technology and working procedure.