On-site testing method for dry density of fine sand subgrade

Abstract

The invention relates to the field of building engineering, and in particular relates to an on-site testing method for the dry density of fine sand subgrade. The method is characterized by at least comprising the following steps: taking out a certain amount of fine sand test pieces from the fine sand subgrade so as to carry out interior dry density testing, measuring the dry density of the fine sand test pieces by a ring cutter, calculating the ratio of the two dry densities as a correction coefficient of the ring cutter, and correcting the dry density in on-site testing of the fine sand subgrade according to the correction coefficient of the ring cutter. The method has the advantages of firstly, being capable of reducing a disturbance zone formed in pressing of the ring cutter and reducing the disturbance degree to the fine sand subgrade by adopting the thin-wall ring cutter, secondly being capable of increasing total mass of samples and relatively reducing the test errors due to disturbance by adopting the large-volume ring cutter, and finally avoiding errors formed by pressing disturbance of the ring cutter through utilizing a large compaction cylinder to stimulate the on-site sand sample and adopting the correction coefficient of the ring cutter to reflect the difference of the test value of the ring cutter and the true value.

Description

technical field [0001] The invention relates to the field of construction engineering, in particular to an on-site testing method for the dry density of a fine sand roadbed. Background technique [0002] Fully compacting the subgrade filler is an important link in highway construction. The way to check whether the degree of subgrade compaction meets the specification requirements on site is to test the dry density of the packing after compaction and compare it with the maximum dry density of the packing. At present, the methods commonly used at home and abroad to detect dry density on site include ring knife method, sand filling method, water filling method, etc. Among them, the ring knife method is more convenient and faster than the sand filling method and the water filling method. The common method is to use a ring knife with an inner diameter of 6-8cm, a height of 2-5.4cm, and a wall thickness of 1.5-2.2mm. Sampling is carried out in the filler, weigh the mass of the f...

AI Technical Summary

Problems solved by technology

[0003] However, for the fine sand subgrade with loose particles, in the process of sampling with the ring cutter, the side wall of the ring cutter will rub against the sand particles, causing the sand particles at the contact surface to roll, resulting in an increase in the void ratio of the sample. large, which makes the test result lower than the real dry density, so the feasibility in practical application is greatly limited

Many engineering practices at home and abroad have proved that the use of the ring knife method for detection often underestimates the on-site compaction effect. The industry standard of our country "Highway Soil Test Regulations JTG E40" also stipulates that this method is only applicable to fine-grained soils.

Images