A method of filling and compacting silty sand subgrade

Abstract

The invention discloses a method for filling and compacting a silt fine sand subgrade. The steps are as follows: A. determining the compaction density of the silt fine sand filler; Test; C. Compaction and split-layer detection of silt fine sand subgrade. Roll with a vibratory roller to press out a layer of rolling layer; select measuring points in the current rolling layer, plan to remove the surface soil layer with a thickness of h0 within the range of measuring points, and test the compaction coefficient K and foundation coefficient K30. Backfill and tamp the silt and fine sand filler in the removed surface soil layer to obtain the current filling layer; D. Use crawler bulldozers for final compaction, and test the compaction coefficient K and foundation coefficient K30 on the surface of the soil layer. The method can effectively reduce the construction cost of the roadbed under the premise of ensuring the compaction quality of the roadbed.

Description

technical field [0001] The invention relates to a method for filling and compacting a silt fine sand roadbed. Background technique [0002] When building roads in river beaches, coastal areas and desert areas, due to the lack of earth and rock fillers, sandy soil is often used for roadbed filling. As a filler, sandy soil has the advantages of high strength, good water permeability, and strong deformation resistance. However, the silt-fine sand has the characteristics of loose structure and difficult compaction because of its uniform particle composition and small bonding force between particles. Therefore, layer-by-layer detection must be carried out during filling, that is, after filling and compacting a layer (30-50cm) of sandy soil, the compaction coefficient K and foundation coefficient K must be carried out on site. 30 Inspection, after the subgrade of this layer is measured to meet the requirements, the filling, compaction and inspection tests of the previous layer ar...

AI Technical Summary

Problems solved by technology

However, during the rolling process of the road roller, the kneading shear stress τ produced by the rolling wheel s Far greater than the shear strength τ of silty sand filler f , causing the surface filling soil to break and uplift and become loose, forming a loose surface layer, resulting in the measured foundation coefficient K of this filling layer 30 and the values ​​of the compaction coefficient K are too small; rolling again will cause shear failure again, that is, it is impossible to increase the foundation coefficient K by increasing the number of rolling times 30 and the test value of the compaction coefficient K; and when the subsequent upper layer of filling is compacted, the loose surface layer of the previous (lower) filling layer will be significantly compacted, and the bearing capacity will be significantly improved

Therefore, the existing sandy soil filling method, because the detection in the filling cannot accurately reflect, but deteriorates the mechanical properties of the silt and fine sand filling under good compaction, resulting in the sandy soil filling that could have been used. Abandoned if it meets the test index, and use scarce earth and rock as filler

If the crawler bulldozer is used to fill and compact the sandy soil, although the surface filling can be well compacted, the construction cost will increase significantly due to the small compacted area and low efficiency of the crawler bulldozer