一、问题的提出利用放射性同位素方法测定土的密度和含水量,已在我国的一些建筑和工程地质部门开始研究。从已有的材料来看,大多数是利用放射性同位素γ射线的散射和吸收方法来确定土的密度,和中子的散射来测定土的含水量。无疑,采用放射性同位素的方法是我们今后尚需进一步研究产加以发展的重要方面,但就目前国内的情况看来,采用这种方法尚受到原料上及 I. PROBLEM PROBLEM The determination of the density and water content of soils by radioisotope methods has been started in some of China’s construction and engineering geology departments. From the available materials, most of them use radioactive isotope gamma-ray scattering and absorption methods to determine the density of soil and neutron scattering to determine soil moisture content. Undoubtedly, the method of using radioisotopes is an important aspect for us to further study production and development in the future. However, judging from the current situation in our country, this method is still subject to the problems of raw materials and