影响土壤比重的因素: 土壤比重仅仅取决于土壤固相颗粒的物质组成。 Since a large portion of most soils is composed of particles derived from quartz minerals, the particle density of most soils is near 2.6 g/cc which is the density of quartz. Variations in the particle density are due to the presence of heavier minerals like iron oxides or lighter organic components
水准测量原理 The Principle of Leveling 水准仪及其使用 The Water Level and the Usage 水准测量的一般方法和要求 The Common Methods and Demand of the Water Level 水准仪的检验和校正 The Inspection and Emendation of the Water Level 水准测量误差产生的原因及消减方法 The Causes and Elimination of Leveling