A Study On Quantitative Research Method About Soil-Rock Ratio In Red-Beds Airports' Excavation Area In Sichuan

With the rapid development of the society and economy, various infrastructure facilities will deep into the red-beds areas according to the national strategic plan for western development. There are some engineering geological problems appeared in the process of survey, design and construction because of the complication and the specificity of the engineering geological condition of the red-beds.The red-beds area in Sichuan is the hilly country. Take into account the flight obstacles, the threat of the flooding, and other factors. The western airport on site located in the ancient planation surface which preserved incomplete and become into a dome shape sub-prime landscape. The large earthwork in the ancient planation surface is one of the main expenditure in airport construction. And the investment of excavation engineering is greatly influenced by soil-rock ratio. The huger excavated rock and soil volume,the higher project cost,the cost of the earthwork and the stonework are very difference. So it is must be firstly solved the problem that the dividing line of the earthwork and the stonework during excavation in order to calculate.Based on the field investigation data and indoor and outdoor geotechnical test results and combined the completed information of the earthwork construction in Sichuan, then come up with the types of soil and rock, the means of survey in excavation, the calculation of soil-rock ratio by comprehensive analysis. Not only can be used as the basis of soil-rock ratio survey in existing construction project, but also play an important role for the further research. In this paper, the field practice and processing of data is based on the theoretical research of geotechnical investigation and earthwork calculation methods, the results are as follows:(1) The weathering of rock and degree of crushing in red-beds area in Sichuan mainly affected by the climate, rock lithology, geography, the rock texture and structure, etc. Then the boundary of soil-rock is vague because of the broken rock.(2) Modern machinery has gradually replaced the traditional tools, such as crowfoot, pickaxe and shovel, etc. The rock stratum is turned into complete, fresh and continuous moderately weathered rock when the mountain cannot continue to excavate by excavator.(3) We can divide into six categories about soil-rock by comparing with parameters related to classify of soil-rock in the data of survey and the difficulty of excavation about all kinds of rock and soil masses. That is loose soil, ordinary soil, hard soil, soft stone, second solid- rock, solid- rock.(4) According to red beds lithologic characteristic, weathering degree and the engineering construction, there are no obvious boundaries in the excavation region about the earthwork and the stonework, so serving the lower limit of intensive weathered layer as the boundaries during survey and putting the rock into"soil", which is above the intensive weathered rock zone. The middle and slightly weathered rocks will put into"rock".(5) The main means of survey in excavation areas are combination of drilling, trench, shallow shaft, geophysical prospecting (resistivity method, acoustic logging, geological radar, seismic refraction wave, wave velocity tests in the field, etc.), in-situ test (cone dynamic sounding tests), then determine boundary surface of the soil and stone according to the related parameters.(6) We can conclude that the HTCAD software and Surfer software base on basic principle of square grid to calculate the soil-rock ratio by comparing the calculation methods in various condition, which considered that the large regional area and calculation in the airport engineering, and all kinds of complex terrain. The HTCAD software can automatically extracted the altitude data in the calculation and more convenient for late calculation; the calculation method of Surfer software not only pay attention to the influence of geotechnical layer thickness which revealed by drilling, but also the changes of bedrock surface and the terrain, and combine with 3D geological modeling, choose appropriate interpolation method of data to grid respectively, then calculate the volume of the rock and soil masses with excavation and bedrock, which derive from soil-rock ratio. These two kinds of methods carry a great load of significance for calculation of soil-rock ratio in red-beds airports'excavation area in Sichuan.