在设备基础密集区采用钢管龙门桩进行定位测量放线 ,不仅能提高工程测量放线速度 ,还能减少工程测量误差。具体做法如下 :(1)在基础密集区 ,离基础基坑外边缘 3ｍ左右 ,基础四周对称钉设钢管龙门桩。(2 )钢管龙门桩的长度 ,以密集区基础横向轴线累计尺寸及纵向轴线累计尺寸的长 In the equipment-based intensive area with steel gantry positioning and measurement of line release, not only can improve the speed of project measurement, but also reduce the engineering measurement error. Specific practices are as follows: (1) In the basic intensive area, about 3m from the outer edge of the foundation pit, the foundation symmetry nail steel pipe gantry. (2) The length of steel pipe gantry pile shall be calculated based on the accumulated size of the transverse axis of the dense base and the cumulative length of the longitudinal axis