Abstract: In order to solve the problem that the moisture content measuring with the washing method is distorted for coarse and fine particles of weathered granitic soils, a dry sieving method is proposed to measure the moisture content of various particles of weathered granitic soils under natural moisture content. The test process of this method comprises the following steps: crushing soil sample with natural moisture content; preliminarily sieving the natural soil sample into subsamples with different gradations; measuring the natural water content of each subsample; and then washing the subsamples with water to separate the subsamples. Considering the loss of water content during crushing and sieving, the graded water loss rate T is introduced. Based on studying the characteristic of weathered granitic soil particle separation curve and assuming that the moisture content of coarse particles is proportional to the specific surface area and combined with the conventional sieving test data, a multi-unknown equation group is established to calculate the water content of each particle and the graded water loss rate T. The results of tests and data analysis show that there is a certain systematic error in this measurement method, which can lead to diversify the calculation results and even result in incorrect solutions. The multiple groups of sample parallel tests can effectively resolve the problem.

Key words: Weathered Granitic Soil, Moisture Ratio of Grains, Natural Moisture Content, Graded Moisture Loss, Specific Surface Area