Applied Mechanics and Materials Vols. 170-173

Abstract: The method of high-low strain test is characteristic of quickness, economy and convenience so that it is widely applied in detecting pile foundations. The text introduces high-low strain tests on many piles of the commercial residential Lingxiutiancheng Building in Dongying, Shandong province. The high strain process is adopted to detect the vertical compressive characteristic resistance and the low strain process is adopted to test the integrity of the pile body. The accuracy of detecting pile foundations has been improved through the comprehensive analyses of the detecting results.

Abstract: We established a calculation model for retaining structures with double-row piles by using the midas GTS finite-element software, considering the interaction between pile and soil and adopting the contact element method, on the basis of a practical engineering application. We then determined a reasonable elastic modulus of reinforced soil bodies, thereby enabling the study of the influences of the reinforcement depth and width in the interpile soil on the internal force and displacement of the retaining structure with double-row piles. We present suggestions for reinforcement depth and width. The study results provide valuable reference for engineering design, construction, and cost control.

Abstract: Along with the vigorous developing construction in the world, the number of various underground engineerings is greatly increasing, such as the foundations of subways, tunnels, dams and high-rise buildings etc., where the attention is always paid to the seepage behavior in the soil around the structures. Seepage flow can lead to both horizontal and vertical displacement, but ground behaviors due to seepage force in traditional methods were rarely considered. In this paper, a 3D analysis is made on the foundation behavior due to seepage force of groundwater. The model uses the finite element method to study the problem and the model implemented by FORTRAN code is applied to predict the flow velocity distribution and deformation results of the simulated domain. The analysis shows that horizontal deformation caused by seepage flow plays a very important role in deformation field, which may lead to toppling behavior to the foundation of high-rise buildings.

Abstract: According to the actual work effect of the disk piles，a model test equipment is designed to research load transfer mechanism of the disk piles in different soil layers. No matter in the same or different soil layers，it is proved by test that the increase of the pressure under the disks of the double-disk pile is nonlinear with that of load，and the development of bearing capacity in each disk is not synchro. When in different soil layers，the laws of load transfer of two disks are completely different, the bearing capacities and deformations of the piles with double disks are obviously different.

Abstract: Coal containing gas is porous material. In this paper, by using the self-developed meso shear test equipment for coal or rock containing gas, shear crack propagation process of coal under different gas pressure conditions was studied, and shear performance of coal containing gas under different gas pressure was also researched. The results show that the gas pressure can hasten the crack growth rate of shear fracture surface, reduce the shear strength of coal containing gas, and accelerate its shear failure fracture process. The shear breaking process of coal results in two cracks: shear crack and tensile crack, and the cracks first appeared in the shear plane at both ends, then extension to the central until shear fracture surface formed.

Abstract: According to the dock engineering, the paper analyzed the settlement and deformation of dock slab of soft soil foundation by using finite element software ADINA, and summarizes the law of the settlement and deformation based on different foundation model, to provide reference for the calculation and design of similar dock engineering.

Abstract: Model experiment box for crushed rock layer to eliminate the differential settlement was designed. Through the model experiment, the effect of eliminating differential settlement was validated and the truth of it was analyzed. Then the concept and the expressions of the secondary loose coefficient was established. Through measuring the secondary loose coefficient of different rock layers by designed measure box, the relationships of grain diameter of crushed rock, grain figure of gravel and the friction angle with the secondary loose coefficient were analyzed respectively. The research indicated that (1) the design of model experiment box and the experiment was successful; (2) crushed rock layer which can eliminate the differential settlement mostly depends on its capability of secondary loose; (3) the secondary loose coefficient increases with grain diameter of crushed rock and the friction angle, and the secondary loose coefficient of crushed rock is always higher than that of the pebble at the same grain diameter.

Abstract: The FLAC3D was used to the fluid-solid coupling numerical simulation of considering the initial state of unsaturated to soil for the deep foundation pit engineering under different rainfall infiltration conditions. By comparing the bending moment, the shearing stress and internal forces of support under the infiltration conditions between non-rainfall and rainfall, the paper focus on the stability of deep foundation pit. Research on the stability of deep excavation under rainfall conditions was a useful attempt. From the detail study of the stability of a foundation pit of Qinhuangdao under rainfall infiltration conditions, the paper have drawn some useful conclusion on the design of building foundation pit, which can be the basis of excavation design and construction under rainfall conditions.

Abstract: The pile-base post-grouting technology can solve the bottom slime and the shaft mud-cake which are the two principal deterioration factors of slurry bored piles. The enhancement effect of pile-base post-grouting was analyzed through the comparison static loading tests and summarization of literature data. The hysteretic nature of the enhancement effect was revealed and the abnormal phenomena was analyzed that the initial loading stiffness of deep pile with post-grouting was lower compared with the pile without post-grouting. The settlement-reducing effect of post-grouting is limited at serviceability limit states and the additional settlement effect of end resistance enhancement of pile with post-grouting is proposed.

Abstract: The contact of nominally flat rough surfaces can be applied in rock joint contact problems. Statistical, fractal and multi-scale models for surfaces under normal loading are reviewed. The assumptions usually used in those contact models are illustrated. The criteria for distinguishing surfaces which touch elastically from those which touch plastically are analyzed. Moreover, the interaction effect of asperities under loading is discussed.