| Loess landslides occurred more related to water, increasing soil moisture is one important factor that leads to disasters. Soil moisture is a decisive factor that also affects the growth of plants, is the basis for the establishment of appropriate irrigation schemes. In addition, studies of groundwater distribution and transport must also be achieved through soil moisture monitoring. Therefore, the investigation of water infiltration of soil has a very important significance. By landslide investigation of Jing Yang southern edge, we find the development law of cracks and sinkholes, and the experimental study to determine the appropriate measurement of soil moisture sensors used to study soil infiltration of the soil column and field test, homogeneous soil and fissures loess infiltration experiments were analyzed. Specific studies include the following four aspects.1. Detailed investigation fracture and sinkholes development law of the southern edge of Jing Yang landslide group, according to the GPS, measuring results and sketch, draw maps of crack and sinkholes distribution, cracks and sinkholes dense area are analyzed in detail. For the distribution of the special area, a detailed analysis of its landslide order and law, found that have frequent disasters than other regions. Cracks and sinkholes provide the advantages flow channels for underwater infiltrated by rainfall or irrigation, the impact of soil seepage induced landslides and other geological disasters.2. In order to achieve rapid, sustained, stable and accurate data monitoring water content, conducting performance testing of moisture sensors. The study found the quality of the water content, volumetric water content, saturation three variables sensor output value(voltage value or dielectric constant) relationship fitting formula, volumetric water content fits best effect. Dry density has little effect on the fitting formula for dry density in the range 1.4-1.6g / cm3 range, we can use uniform calibration formula. Compared to the factory calibration is recommended formula, after special tests of soil samples for calibration, measurement accuracy has improved significantly.3. In order to improve the efficiency and accuracy of filed infiltration and soil column test, we designed and developed new modular soil permeability tester and easy to install and fixed type bicyclic infiltration-meter evaporation. For New soil permeability equipment, modular components can meet the homogeneous soil, soil cracks, waste soil, permafrost, interbedded soil, soil percolation tests with a variety of properties of soil geo-synthetics, etc., and it’s easy to change the flow conditions and sensor layout program, so capacity utilization is high, test equipment has diversity and economic characteristics. Tension meter, water meters and barometer have a good reflects changes in migration of the process of infiltration of water and air pressure. Tension meter test results are the best indicator of the depth of infiltration changes. Water meter are influenced by dry density of the surrounding soil, when the probe is close to looser loess, there will be significant fluctuations in moisture meter peak of the curve segment.4. To test the soil permeability closer to the actual conditions and improve the accuracy of infiltration test for field homogeneous soil and field fissured soil. Soil infiltration rate variations are experienced rapid decreasing, gradually decreasing and remaining stable phase. Because of the field unevenness soil density unevenness, resulting in reduced infiltration rate fluctuations that occur during post-test changes and moisture infiltration cross-section of local moisture content is too large. Whether homogeneous soil or fractured soil infiltration significantly, since the outer ring with the horizontal diffusion, the inner ring infiltration results are more accurate. Due to the presence of fissures, providing advantages for the infiltration channels, fissured soil infiltration rate are significantly higher than the uniform. Taking SL237 specification recommends two formulas to calculate site soil saturated hydraulic conductivity, the results are too large, the reason for the H3 will take definite values, without considering the actual soil suction changes and H3 is definite values. Thus, there should be further discussion for H3 values. |
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