Advanced Materials Research Vols. 639-640

Abstract: Considering the rheological mechanical characteristics of rock mass, a viscous-plastic model of rock mass which can describe the acceleration creep stage of rock mass was proposed. Moreover, combining with viscous-elastic shearing rheological model of rock mass in series, a new constitutive model of visco-elasticity-plasticity considering the rheology was constructed. Due to the shearing rheological curves of granite, the model of visco-elasticity-plasticity considering the rheology was identified and the rheological parameters of the model were obtained. The comparison between the viscous-elastic-plastic rheological model of rock mass and experimental result of granite shows that the accelerating rheological properties of rock mass can be depicted effectively by the constitutive model of visco-elasticity-plasticity considering the rheology.

Abstract: Based on the principle of Bayes discriminant analysis, Bayes discriminant model (BDM) for evaluation of expansive soil in sub-grades is established. Four indexes including free expansive ratio, liquid limit, plasticity index and moisture content of standard absorption are selected as the factors for synthetic evaluation of expansive soil. The grade of shrink and expansion is divided into four grades that are regarded as four normal populations in Bayes discriminant analysis. Bayes discriminant functions obtained through training a set of expansive soil samples are employed to compute the Bayes function values of the evaluating samples, and the maximal function value is used to judge which population the evaluating sample belongs to. The optimality of the proposed model is verified by back-substitution method. The study shows that the prediction accuracy of the proposed model is 100% and could be used in practical engineering.

Abstract: To meet the punching requirement of rectangle extended foundation under column, it is common practice to assume foundation’s height first, and then use the formula to check according to the current code. If the foundation’s height is not suitable, set it again to check until a suitable value. It is found that the minimum height of rectangle extended foundation under column can be solved directly, and all larger than the minimum height can meet the punching requirement through analysis program taking MATLAB as a platform for everyone to use.

Abstract: The Soil Improved shearing displacement law is used to analyze Pile-soil interaction and this method can consider stratified foundation, but can’t consider pile-soil slip. An improved shearing displacement law analyzing pile-soil interaction was proposed in this article which could think over pile-soil slip on interfaces and interaction of pile-soil on stratified foundation. Rock and soil’s parameter is very crucial in geological engineering, the soil parameters were determined by parameter back analysis theory and the stress and deformation characteristic for vertical loading piles were analyzed by the improved shearing displaces law. These process was simulated by my own program. The calculation results show that the axial force of pile decreases with pile depth and the pile tip axial force is zero. The pile bottom resistance increases with load and the soil’s resistance increases with the relative displacement between pile and soil. But,the frictional resistance growth rate with displacement is different in different soil. The silt’s growth rate is minimum and the medium-fine sand mixed mucky soil is maximum. The pile frictional resistance increases with load and depth. It has greater directive significance for the pile design.

Abstract: Based on the vertical loading test results of large-diameter filling pile near an electric factory in the sandstone and mudstone foundation, the load transfer mechanism and vertical loading bearing behavior of the pile were discussed. The analysis shows that the pile mainly behaves as friction piles and the vertical bearing capacity is mainly supplied by side friction resistance. The pile side friction is related to the section displacement of pile, the pile load and the soil characteristic. The pile end resistence is related to pile end settlement, pile diameter, rock-socketed length,rock elasticity modulus of pile end, sediment thickness and pile construction technical. The pile end resistence linearly increases with the settlement of pile end. In tis paper, the dead-load test is recommended in determination the pile bearing capacity and the sediment thickness should be strictly controlled in order to meet the standard. In the intermediary weathered sand-mudstone, the pile end should inset two times of pile diameter for pile whose diameter is 800mm. The pile end should inset 2 meters for pile whose diameter is 1500mm.

Abstract: According to finite element strength reduction method，the article has discussed the failure mechanism of anti-sliding pile by using finite element software MIDAS /GTS ，exploration report and anti-sliding pile design data.The comparative analysis shows that the failure of anti-siding pile is contributed by the slope excavation and rainwater.The analysis method and results can provide reference significance to other anti-sliding pile design.This paper also provide a feasible method for prediction of consequence in slope excavation.

Abstract: The residual strength is one of the most important strength parameters to evaluate the stability of a reactivated landslide slope, but the relation between residual strength gained by using ring shear tests and shear speed still remains unclear. In order to clarify the relationship between them, the variation in residual friction coefficient of slip surface soils with shearing rates were calculated and discussed in this paper by means of an undrained ring shear apparatus on Miaowan sample of China-Loess Plateau , predominantly consists of silty-sandy(81.3%), and Kamenose sample of Japan, predominantly consists of clay(73.2%) in texture .The residual friction coefficient was observed to be lower for higher shear rates in Kamenose sample;while the variation of its shear behaviour at different shear rates is fluctuant in Miaowan sample. This change in pore water pressures and soil texture could be thought as the rate effect mechanism of residual shear strength.

Abstract: Based on the strength reduction method，the anchor reinforced slope has been simulated by elastic-plastic FEM. The safety factor of reinforced slope with anchor was gotten by heuristic search method. The plastic zone running through or not is taken as a standard to solve slope safety factor. The research results show better the distribution situation of stress and strain in slope. It proposes a new method to evaluate the stability of slope with complex boundary conditions. Taking a slope engineering for example, the stability safety coefficients of the slope are calculated when the slope is reinforced with anchors of different length. When the design length of anchor is longer than a certain value, the anchor length has little effect on improving the stability of slope and slope toe. Consequently, the reasonable design length of anchor is put forward

Abstract: Abstract. Slope supporting piles and enlarged prestressed anchorage was used to support the deep foundation pit in Beijing which is a complicated engineering and influenced by many factors that locating in the midtown of Beijing city and nearby the construction, traffic trunk and underground pipelines based on the hydrological datum and geological conditions through the specific analysis of the actual conditions, surroundings and geological conditions of the site. Then taking full advantages of the large resist pulling force of single anchorage, small displacement and high reliability of enlarged prestressed anchorage and ensures the engineering be carried out safely and successfully.

Abstract: Many cast-in-site bore pile have broken pile because of collapsing in wall of holl. Based on the principle of mechanics, a new combination approach was proposed for dealing with the broken pile. The approach is displacing the soil in the pile by cement paste and increasing the height and the steal ratio of the top beam which is on the defect pile. Using the finite element software, we have set up the analysis model of the approach, which helps to demonstrate the rationality of this method. This method can be referenced by the reinforcement and maintenance of the bridges.