Applied Mechanics and Materials Vols. 204-208

Abstract: The active earth pressure on rigid retaining wall is analyzed using the finite element software ABAQUS. The fill behind the wall is sand and the Mohr–Coulomb constitutive model was used to model the stress–strain behaviour of soils.The finite element analysis results were compared with the Rankine results. The maximum error of the results is about 10% and the finite element analysis result is bigger. So the result obtained from the finite element method could safely be used in actual projects.

Abstract: In the coal mine of Huaibei Mining Area, based on the character of thick dirt band in the coal seams and the influences to top coal caving, the physical and mechanical properties of dirt band were analyzed. In order to improve the recovery rate of top coal, the failure mechanism of dirt band was analyzed through the cantilever beam model, and the sensitivity analysis to the length of dirt band overhang was done in the conditions of different mining height and dirt band thickness. The results show that, the average water absorption of dirt band samples is 3.5%, and the soften coefficient is 0.71, which presents that the dirt band have large softening property and poor engineering geological property. When the thickness of dirt band was more than 3.5 m, the top coal could not be caved smoothly. However, the bigger underground pressure would be helpful to the broken of dirt band and top coal seams, and the recovery rate of top coal was improved.

Abstract: The pumping tests on the hydrogeology, including single well tests, group wells tests and land subsidence analysis, were carried out for Tianjin transportation center project. The straight-line graphical method, curve fitting method, formula method and infiltration curve extrapolation method were applied to obtain the permeability coefficients and influence radius of the main aquifers, and to obtain the mutual influence between the aquifers. The results of the land subsidence observations indicate that amount of land subsidence decreases with increasing distance from the wells. And it is also found the land subsidence of a band range is obvious, and its distribution changes unregulated. It could be preliminarily inferred that this anomaly is due to the venue internal west alkali river that has been recently backfilled.

Abstract: The Chinese Dynamic Penetration Test (DPT) was used following the 2008 Wenchuan earthquake to measure penetration resistances of gravels that liquefied and nearby gravels that did not. The test has many advantages, including simplicity, continuous data acquisition, and robust equipment that is easily transported by light vehicles and low cost. A probability formula, developed from logistic procedures, was proposed using the 47 compiled DPT data. The DPT could be a viable test for measurement of penetration resistance of gravels in other parts of the world beyond China.

Abstract: Because development degree and order as well as decay rate and degree of shear strength indexes, cohesion C and angle of internal friction , are not equal as slope failure, both should have their own security reserve. For this reason, it was proposed that C and  should have different reduction-factors, rather than same about strength reduction method (SRM). And to take a slope as an example, by FLAC SRM and strength reduction slice method (SRSM), reduction-factors of the two indexes and dangerous slide surfaces of the slope were computed and comparatively analyzed under 9 different reduction conditions. The results obtained by FLAC SRM and SRSM accorded with each other well. Therefore conclusions can be drawn that different reduction conditions correspond to different two reduction-factors and dangerous slide surfaces, so that all these dangerous slide surfaces form a dangerous slide region; single reduction-factor method that reduction-factors of C and  are same is only a special case of two reduction-factors method; two reduction-factors method can just reasonably reflect respective roles of C and  as slope instability. The conclusions in turn confirm the above-mentioned viewpoint again.

Abstract: Cohesive sediment is a major component of clay. Its erosion and movement has a significant impact on the soil environment. Moreover, cohesive sediment is an important part of the sediment of lakes and oceans, and its movement and transportation also have a crucial influence over dispersion of pollutants in water. Open channel flume experiments were carried out to study the characteristics of cohesive sediment movement; simultaneously the velocity and sediment concentration vertical profile was investigated. The experimental results indicate that under the conditions of suitable hydrodynamic velocity and sediment concentration, a special-shaped sediment flow, stratified movement, takes place in the flume. Its formation and features are closely related to fluid parameters and sediment concentration. Its velocity distribution shows a V-shaped pattern falling forward. At the corner of V, the maximum velocity is vertically located in the middle of the flume. The concentration distribution is vertically stratified into three discrete layers on whose interfaces the concentrations change suddenly. To form lamination movement, different hydrodynamic conditions are required under different sediment concentrations. When the concentration increases, the corresponding flow intensity also increases.

Abstract: The cause of longitudinal cracks on the top of the large locks built on soft foundations can’t be explained by general design methods. Based on the analysis of influence of foundation elastic rebound and concrete hardening on the response of elastic foundation beam, the paper thinks it is an important cause that designers ignore the above factors of the construction process, and considering the worst case, and suggests designers should ignore the affection of the lock floor’s deadweight when computing the negative moment.

Abstract: A series of consolidation and drainage unsaturated triaxial tests on remolded samples were carried out at controlled matrix suction and confining pressure through automatic GDS triaxial apparatus. According to the shear strength of unsaturated silt, the results show the matrix suction has a little influence on effective angle of internal friction, while has great influence on failure modes and cohesion. With the increasing of matrix suction, stress-strain curves translate from hardening type to softening type, the effective angle of internal friction changes a little and is approximately equal to the effective angle of internal friction of saturated soil, cohesion is significantly improved. Matrix suction friction angle is not a constant, when the matrix suction is less than 100kPa, it decreases with matrix suction increasing, the rate of decrease reduces gradually; when matrix suction is greater than 100kPa, it tends to be a fixed value. The results are consistent to modified strength theory proposed by Fredlund.

Abstract: A new computational method of preloading the earthwork has been proposed in this paper. Firstly, the various factors affecting the computed method for the foundation of the average degree of consolidation have been analyzed. Secondly, the settlement prediction method has been described according to the settlement to calculate the degree of consolidation. Then the consolidation coefficient has been calculated according to the least square method. The computed algorithm compute the preloading height based on the Takagi Shunsuke method and the measured data is presented. Finally, two examples illustrate the validity and the feasibility of the computed method in this paper.

Abstract: The dam concrete material properties wre influenced by the implementation of temperature control measures on site. The weekly temperature evaluation system has been set up in order to evaluate current temperature control measures, combining with the distributed optical fiber temperature control techniques and construction technical requirements. The system has been applied to a concrete arch dam under construction in southwest China which established multi-objective fuzzy mathematical model by synthetic weighting method that was a combination of experts scoring method and entropy weight method. Practice shows that the system can estimate weak link of this week and give guidance to the temperature control’s adjustment of the following week.