The Influence Research Of The Migration Of Water Environment Caused By Construction Of Highway

Soil is the medium of water permeability, but the natural structure of the soil will be changed by the construction of the way. Then a series of phenomena such as the change of the permeability of soil, water seepage path changes, abnormal fluctuation of the water level can be seen gradually, greater impact on water environment will happen especially for the highways that cover an expanse of land and that with large amount of excavated volume or back fill. With the constantly development of society and improvement of different regional connectivity’s demand, make the highway’s development more rapidly, water environmental damage caused by construction of highways are starting to show, hope to draw great attention from all walks of life, strengthen study and explore the management way. In this paper, the research of permeability’s changes caused by the soil stress state has been done, and made the following contents:1. The water environmental damage phenomena caused by construction of highways are studied, analyze the relationship between soil permeability’s change and the influence which including regional water level abnormal fluctuation and natural migration state change of water flow caused by highway construction, summarizes the theory of consolidation and permeability related;2. The new permeability instrument was R&D and trial-produced based on the traditional NDZS variable head permeameter in this paper, so that the permeability test and compression test can be conducted. The pressure loaded on the specimen can be applied continuously, and the soil permeability under different pressure also can be measured. By comparing the test result between pure permeability test and compression test traditionally and the modified osmotic oedometer, we can found that the test results using improved osmotic oedometer were with higher accuracy and more convenience.3. Take the roadbed of Fuzhou-Yinchuan expressway Jiujiang highway bridge which across Yangtze River as an example, using silty clay taked from engineering area to carry on the seepage-consolidation combined test. Permeability coefficient and void ratio under four cases are obtained through experiment, on the basis of the basic indicators such as the specific gravity, the density, the moisture content, the liquid limit and plastic limit of the soil have been measured, using Origin8.0 software for data processing, analyzes permeability coefficient’s change rule under the different void ratio e, initial compaction Dc and different load p. The experimental results showed that:(1) e-k curve of silty clay samples conforms to logarithmic relationship, obtain fitting curve formula and parameter values, from the degree of compaction that is same or not to analyzes the influence of void ratio on soil permeability, when the compaction degree is equal, the permeability coefficient decreases with the reduction of void ratio, and when compaction degree is not at the same level, in the decreases process of porosity ratio, the permeability coefficient of soil samples with high-pressure compaction degree always less than that with low-pressure compaction degree.(2) analyzes from the angle of the compaction degree, change rules such as the compression coefficient av, permeability coefficient k and the initial void ratio e0 were analyzed with the increase of compaction degree on the basis of the experimental data and painted e-p, k-Dc curve.(3) analyzes from the angle of the load, we found that p-k curve conforms to logarithmic relationship, and compared with boltzmann model, its’ fitting degree is higher, both compressibility and void ratio of the soil decrease with the increase of load.