国家水准测量依精度不合分为一(国外英文资料).docVIP

国家水准测量依精度不同分为一(国外英文资料) The national level measurements are divided into one, two, three, four, etc. A, is the national second-class leveling elevation control comprehensive foundation, three, four etc. Leveling directly for topographic mapping and various engineering construction to provide the necessary height control. The level of accuracy below four is called an iso-level measurement. This section describes the layout, technical requirements, the selection of the buried rock, the external industry and the calculation of inner industries. The form of the layout of the standard route The route taken by the level origin or any known elevation point is called the standard route. The standard route requires a fixed point at a certain distance, called a level point. The goal of leveling is to measure the elevation of the level points along the selected level line by the known elevation point. According to the situation of the known level and the actual needs of measuring work, the standard route can be set in three forms. (1) the level of the line: from the level of a known elevation, the standard measure is carried out to the level of another known elevation. (2) closing level line: starting from the bench mark of a known elevation, along a circular route for leveling, determining the elevation along sheung shui on time, finally returned to those on time. (3) A level line, starting from the bench mark of a known elevation, along a level measurement along the route other leveling point elevation, finally with any known elevation point measurement. In order to improve the accuracy and reliability of the results, the code level line must be observations or one-way double point back and forth, and should limit the length of branch level line. (4) level net The main technical requirements of the measurement of two, four, etc The leveling of the instruments used by type, level line length, discrepancy or closure of the limit of poor have corresponding regulation, four etc