Study On The Crushed Stone Layer In Pavement Widening

With the development of our country,some early-built expressway are urgent to upgrade and reconstruct. Lack of drainage system especially the underground drainage structure result in high water content in subgrade. With the opportunity of widening old expressway, that using the crushed stone drainage layer to treat the roadbad is a effective maintenance method. The main content of this paper followed:That investigation on field mainly aims at pavement and roadbed's disease and the drainage system. The prupose is analysing of disease mechianism and finding out the reason of excessive moisture content in roadbed.It carries on the laboratory test to the subgrade soil and analysis capillary water upward movement law. It uses the well-known Canadian geotechnical engineering software Geo-studio to module for the two soil capillary water upward movement. Through comparison of software simulation and laboratory tese result,we can find the way to estimate the maximum height of soil capillary water by using SWCC. It also studies the factors which affect the height of soil capillary water with software simulation.It uses stuffing theory to obtain the gradation of crushed stone and carries on the capillary water test separately to three kind of different thickness of the gradation. It finds out the gradation which can cut off the capillary water but also has enough strength. It also introduces the construction technology for the crushed stone drainage layer. It simulates the actual effect of this drainage layer in widening subgrade by using SEEP/W software and analysis of the effectiveness of this crushed stone drainage layer. At the end of this paper it gives some proposals to synthetic drainage system of the testing road.