Study on Material Physical and Mechanical Characteristics Tests on Tailing Dam

The article takes tailings dam material as study object. A series tests, including particles analysis test, density test, seepage test, static treaxial test and compression test were conducted to analyze the physical and mechanical properties of heap dam materials. The characteristic curve and data were received. The result can system analysis the deformation laws of dam material. Experiments show that the compression coefficient of tailings is sensitive to void ratio. Through analysis of the strength parameters of the tailings in static triaxial test, it is known that the tailings cohesion can be neglected as 0 and the change of dry density has a larger influence on strength of tailings material.

Comparison of Dynamic and Static Triaxial Test on the Soil-Rock Mediums

By using dynamic and static triaxial experiments to test the saturated composite soil-rock medium of different soil-rock ratio. Measure related power indicators and analyze the variation rules and tendency, and make comparative research on the dynamic and static strength of composite mediums with different soil-rock ratio. Studies have shown the tendency that the static strength and internal friction angle increases while the cohesive force increases and then decreases with the decrease in soil-rock ratio. Under the same compactness, the dynamic strength of composite soil-rock medium increases with the decrease in soil-rock ratio, and decreases significantly with the improvement of seismic intensity; For one rock ratio, dynamic cohesive force decreases with the gradual increase of intensity, and decreases faster with the decrease in soil-rock ratio. While the dynamic internal friction angle decreases with the increase of intensity. At the same intensity, which means the same vibration frequency, dynamic cohesive force increases with the decrease in the soil-rock ratio and so does dynamic internal friction angle.

Alternative method of determining resilient modulus of subbase soils using a static triaxial test

The cyclic test for the determination of resilient modulus (MR) is often too complex and time-consuming to be applicable on a production basis. Therefore, the development of a simple and reliable alternative MR testing technique is essential for the application in the mechanistic design of a flexible pavement system. Seven disturbed subbase soils were collected from the actual pavement projects for testing. To evaluate the effect of particle size on MR, standard MR tests with various maximum particle sizes and specimen diameters were performed using three subbase soils. The resilient moduli determined from various specimen sizes with the same particle-size distribution were almost identical. However, the value of the slope parameter k2 in the bulk stress model was constant, but the value of k1 increased with a decrease in maximum particle size. The effects of mean effective stress, loading frequency, and number of loading cycles on modulus were evaluated from torsional shear (TS), triaxial (TX), and MR tests. The alternative MR testing procedure using the static TX test was proposed considering deformational characteristics of subbase soils. The predicted MR values from the proposed method matched well with those determined by the standard MR test, showing the capability of the proposed method for determining MR.Key words: resilient modulus (MR), alternative MR test, subbase soils, triaxial compression test, deformational characteristics, particle size.

Alternative method of determining resilient modulus of subgrade soils using a static triaxial test

The resilient moduli (MR) of subgrade and subbase soils are very important properties in the analysis and design of a flexible pavement system. However, difficulties and complexities in performing cyclic MR testing and the high cost of the testing system have prevented the cyclic MR test from becoming a routine test. Therefore, the development of an alternative simple and reliable MR testing technique is essential to the application of the mechanistic design of a flexible pavement system. In this study, an alternative MR testing technique for subgrade soils was developed using a static triaxial compression (TX) test. For the development of the alternative testing method, the effects of strain amplitude, loading frequency, mean effective stress, and number of loading cycles on the resilient modulus of subgrade soils were fully investigated. Cyclic MR, static TX, and resonant column – torsional shear tests were performed to evaluate the deformational characteristics. Synthetic specimens of known stiffnesses ranging from those of soft subgrade soils to those of subbase materials were developed, and all of the testing systems used in this study were calibrated. The alternative MR testing procedures were proposed considering deformational characteristics of subgrade soils. The reliability of the proposed test method was verified by comparing the moduli determined by the proposed alternative MR testing method with those determined by the standard MR tests.Key words: resilient modulus (MR), alternative MR test, subgrade soils, static triaxial test, deformational characteristics.