Advanced Materials Research Vols. 671-674

Abstract: To get the accurate gas pool dynamic measurement is the one of the basic work of oil field development. The geologic conditions, one of the aspects, limited the gas pool. It often appears reshooting another layer to commingled production or block off the seriously water producer in layer adjustment, calculation of reserves depends on the alteration of the model condition. Through the material balance and its further work, set the gas pool reserves calculation methods under the layer adjustment condition. The closed constant volume gas pool, its drawdown curve becomes the transition with the adjustment of the layer. Through the original formation pressure with two different slope straight lines before and after adjustment, Using linear extrapolation can get the reserves before and after adjusted.

Abstract: Although the settlement of ultra-soft clay improved by the vacuum preloading technique was large in land reclamation projects, usually exceeding the theoretical calculation value by a large amount, the strength increase was relatively small. As a result the foundation would not meet the design requirements for strength. So a test was conducted to investigate the effect and mechanism of long-term consolidation of ultra-soft clay in laboratory in a period of over 691 days. A preloading load of 80kPa was used in this drainage consolidation test. The test result showed that for the ultra-soft clay with a high initial water content but a small strength, the settlement is large with a large strength increase, but the shear strength was relatively low. These results should draw much attention in application of vacuum preloading technique in construction projects.

Abstract: The un-drained shearing deformation modulus of clay will degenerate under cyclic loading. This degeneration is attributed to two reasons, the first one is the reduction of effective pressure due to the increment of super pore pressure; another one is the change of soil’s structure due to the accumulation of plastic shearing strain. Firstly, based on the result of un-drained shearing tests, two formulations were obtained which include initial deformation modulus ratio versus over-consolidated ratio and initial deformation modulus ratio versus initial shearing strain. Then, the quasi-over-consolidated ratio was introduced to consider the effect of super pore pressure, and a fitting formulation was applied to consider the influence of shearing strain. At last, the degenerate formulation of saturated clay’s deformation modulus was deduced, which was proved reasonably by the test results.

Abstract: Drinking fluoride water is the root cause of serious endemic fluorosis in Gaomi. According to the investigation and sampling test, this paper analysis the relationship between high fluoride water and stratigraphic units and topography: in stratigraphic, high fluoride areas, heituhu Formation and the Yihe Formation are consistent; in topography, high fluoride areas and flood plain landscape are matching. Thus we can summarize the conditions for the formation of high fluoride water. Depending on the analysis of the data, this paper points out the relationship between the fluorine and other elements in the water, especially the fluorine’s close relationship with Mg, Se, Sr. Countermeasures Measures and suggestions on fluoride removal are also provided.

Abstract: The landslide runouts not only were controlled by the volumes and vertical movement distances, but also the underlying surface played an important role. The concave, fold line, ladder and bedded types of the landslide underlying surfaces were studied. It aimed at analysis the underlying surfaces influenced on the runouts of the catastrophic landslides. There was significant correlation between the horizontal distances and the volumes, vertical distances in the seismic and rainfall landslides without river blocking. But the relationships showed different power laws in the seismic and rainfall landslides. The relative errors between actual and forecast values of seismic and rainfall landslides reflected that the underlying surface types influenced on the landslide horizontal movement distances. The results showed that the maximum horizontal distances of seismic and rainfall landslides could be predicted based on the landslides volumes, vertical distances and underlying surfaces.

Abstract: The Duncan-Change constitutive model of rockfill materials is used to characterize the behaviors of modeled rockfill materials. A parameter estimation procedure based on neural network is developed. The material parameters for the rockfill materials are determined from the experimental results of triaxial compression. The investigation results reveal that the identified model parameters can provide satisfactory prediction of the behavior of the rockfill materials tested.

Abstract: Through a series of tests on saturated remoulded clay, initial shear stress on dynamic shear modulus and damping ratio under the condition of large strain(>10-3) is examined. The test data indicate that initial shear stress effects on stress-strain relation and dynamic modulus and damping ratio are obvious. With the initial shear stress increasing, the characteristic of the stress-strain relation changes from cyclic deformation to accumulative deformation, and there is difference in variation pattern of dynamic shear modulus and damping ratio with cyclic number increasing.

Abstract: The selection of material parameters relates to the excavation stability of the underground caverns. However, back analysis is an efficient method to evaluate mechanical parameters. Given the defects of BP neural network, such as low capability of generalization and long training time, by using GA, which have global optimization ability to optimize the BP neural network weights. The parameter of surrounding rock was designed by uniform and orthogonal method, not only reduced the iterative time also improved the accuracy of the prediction. The proposed method is further illustrated with its application to the underground cavern of Lvchunba railway tunnel. Based on the surrounding rock’s parameters obtained by back analysis, the displacement of the surrounding rock was predicted. The results showed that the error between numerical calculation value and actual monitoring value was 13.2%,-8.3%,-8.9%,9.4% respectively.

Abstract: Xiufengsi Landslide is an ancient landslide in Wushan County, Chongqing, China. Under natural condition, this landslide is stable. Due to the Three Gorges Reservoir, however, the water level in this region fluctuates within the range of [145 m, 175 m], periodically. Furthermore, an increasing number of residential quarters have been built on this landslide that also increase the possibility of occurrences of the landslide. Motivated by the government’s desire to take measures in control the landslide, we use two approaches to study the stability of this landslide. Under different computational conditions, the safety factors of the landslide are calculated by using limit equilibrium method and finite element method, respectively. Based on the comparison of the results, the stability of the landslide is analyzed more objectively and comprehensively. This work also lends insight into the landslide forecast.

Abstract: Field test data from three instrumented large diameter bored piles in Pattaya city of Thailand were analyzed to study the behavior of load transfer mechanism from the pile to soil. The pile load test data were obtained from conventional static load test. These bored piles used for conventional static load test have the same diameter of 0.80 m and different length in the range of 25 m to 32 m. Results from back-analysis found that the skin friction resistance, β, has the value between 0.20 and 0.64 and the bearing capacity at end of piles, Nq, which is in the range of 10 to150, is much lower than the theoretical values proposed by other researchers before.