Applied Mechanics and Materials Vols. 580-583

Abstract: Red clay belongs to region special soil.It has engineering geological properties that are different from general soils.The natural red clay has high ratio void ratio,high moisturecontent,low density and so on.But red clay has non-corresponding high strength,bearing capacity of foundation and low compressibility. With the high speed development of China economy,the main soil named red clay in South is used as bearing stratum of many building foundations.However,when red clay is used as foundation,it is regarded as gerenal clay to consider its bearing capacity of foundation.So this will cause two disadvantages.First,potential is not given full play,resulting in considerable waste.Second,red clay has some special properties,such as high woid ratio,softening in water.These properties will bring hidden troubles,causing some bad accidents.These are caused by lacking of knowledge to engineering properties.Xiamen locates in southeast of China,and red clay is widely distributed.It is formed by accumulation through laterization of granites and basalts.So it is essential to study red clay.In this article,literatures of red clay in Xiamen are collected.Indoor conventional geotechnical tests are done,some engineering property parameters are obtained.

Abstract: Several laboratory model tests were carried out on the bearing capacity of strip footings on reinforced soil foundation and reinforced slope. Compared with unreinforced cases, the deformation and failure of reinforced earth in different foundation conditions were monitored and analyzed. In order to visualize a failure mechanism when the ground reaches the state of limit equilibrium, a new numerical procedure was proposed. Assuming an elastic-perfectly plastic model, a smeared shear band approach and a modified initial stress method enable the proposed procedure to create an explicit collapse mode by the stress yield condition. On the basis of the development of failure mode and deformation of foundation, the bearing capacity of strip footings can be significantly increased by the inclusion of geotextile. And because the procedure considers the stiffness and deformation of the material, it may be applied to complex stability problems.

Abstract: GFRP bars and PC strand composite pile is a new supporting piles, according to the engineering field test and analysis of experimental data prove that there is a significant effect on the control aspects of the horizontal displacement of supporting piles. Principle energy method can calculate the horizontal displacement of pile foundation pit in theory, by comparing the size of the horizontal displacement of the supporting piles of ordinary reinforcement, to demonstrate the feasibility of using GFRP bars and PC strand combination of techniques to reduce the horizontal displacement of excavation, provide reference for future engineering practice.

Abstract: Piles are used widely for stabilization of landslides. To stabilize a slope settled on bedrock with piles the required factor of safety must be checked, and pile should be designed properly. Piles should be socketed into firm rock to prevent uprooting or overturning .In this research it is aimed to look into the socketed length of pile in bedrock. Therefore the parameters that affect the factor of safety of slope/pile system such as location, length, spacing and diameter of piles are analyzed. The effect of socketed length of pile in rock on pile behavior is investigated by plotting the shear force and bending moment diagrams along pile. The optimal pile position is found to be located slightly upper of the middle of the slope. The minimum socketed length after which the factor of safety will be remained constant is found to be 0.12L where L is pile length.FLAC3D computer code based on finite difference method is used to simulate the slope/pile system.

Abstract: Wujiang Bridge is located on the Wujiang River in Chongqing Province in China. Based on test method of numerical simulation, the bearing characteristics of this large-diameter rock-socket pile with super-thick pile caps have been analyzed, including pile foundation load-bearing characteristics, pile-soil load sharing, and stress flow analysis of thick pile caps. The results indicated that Q-s curve of this kind of pile is approximate to linear. Under the action of ultimate load, the main load was supported by pile end résistance. And according to main stress distribution of pile cap, there is an obvious spatial truss effect phenomenon in it.

Abstract: A new displacement time series predicting model was proposed by combining the Support Vector Machines and the Markov Chain, which was named as Support Vector Machines and Markov Chain (SVM-MC) model. Through studying the measured displacement, SVM optimized by particle swarm optimization (PSO) was used to forecast the trend of macro development in roll. Markov chain was applied to compute State Transition Probability Matrix. By classifying system state and calculating absolute error and relative error between measured value and SVM fitting value, the predicting results are improved. The model was used on predicting displacement time series of a high slope of a permanent lock. The engineering case studies indicated that the model was scientific and reliable, and there was engineering practical value for displacement time series forecasting.

Abstract: Tube well dewatering is widely applied in deep foundation pit for its large water discharge, good dewatering effect, simple equipment and easy maintenance. In this paper, rube well dewatering is designed for the temporary project of foundation pit according to the engineering characteristics and stratum and underground water distribution with the deep foundation pit engineering as the background. The required parameters and design process of well tube dewatering are illustrated, and experience of applying tube well dewatering in evacuation of deep foundation pit is accumulated, which will be of certain referential significance for similar projects.

Abstract: Discrete element software is used to simulate the excavation of a rock slope in Puli-Xuanwei Expressway in Yunnan Province. Through monitoring displacement development characteristics in different positions of slope, the result shows that the minimum horizontal displacement under excavation exists in the top of the slope, meanwhile the maximum horizontal displacement occurs in the foot and waist of the slope, and the maximum vertical displacement occurs in the top of the slope. Comparing rock slope in such conditions as different stratum angles, directions, rock characteristics and thickness, it concludes possible failure modes of slope and the variation law of safety coefficient under different conditions. This paper is instructive and offers reference for the practical engineering.

Abstract: The compressive strength of cement stabilized macadam base is an important index to evaluate the quality of road construction. In this paper, investigation and field sampling were conducted on roads in Shenyang city, and, indoor experiment study was then adopted to analyze effects of particle grade, cement dosage, molding method, compaction and curing age on compressive strength. The results show that rational particle grade greatly enhances the strength. Strength of vibration molding sample is closer to the field sample strength and is 0.6 times bigger than that of static pressure molding sample. 1% increment of construction compaction degree will induce 10% increment of compressive strength. Increment of cement dosage and curing age will induce increment of compressive strength, but the effect is limited. Studied in paper can provide a theoretical basis for site construction in Shenyang area.

Abstract: In this paper, the dynamic characteristics for three different kinds of copper tailings are studied through a series of cyclic triaxial tests. It is found that under confining pressure 200 and 300 kPa, elastic modulus raises with the increasement of coarse grain content to a certain degree and then declines, and the maximum elastic modulus corresponds to good gradation. While, as for confining pressure 100 kPa, elastic modulus raises with the increasement of fine grain content. It is also found that elastic modulus raises with the increasement of confning pressure. And, damping ratio raises with the increasement of shear strain and finally to a stable value. Finally, the fitting G_d/G_dmax~ curve for three kinds of tailings shows the reasonableness of test results.