Applied Mechanics and Materials Vols. 204-208

Abstract: A systematic and comprehensive study on the design, construction and testing of large scale of Ⅲ～Ⅳ grade wet-collapsible loess foundation treatment by 8000 kN•m high energy dynamic compaction is done in this paper. Effect on the treatment for collapsible loess foundation by dynamic compaction is analyzed through Rayleigh wave velocity test, standard penetration test, lab soil test and static cone penetration test. By comparison with physical and mechanical properties index of the foundation soil without dynamic compaction treatment, the effective reinforcement depth, the elimination of collapsibility and the bearing capacity of foundation are found to meet the design requirements. The results of this paper could supply some reference for the design, construction and testing of other collapsible loess foundations by dynamic compaction treatment.

Abstract: This paper describes the successful experience of the directional control blasting demolition of 150m-high reinforced concrete chimney and 75m cooling tower of Shizuishan Power Plant in Ningxia. It emphatically describes the pretreatment measures, blasting cut shape and size, blasting parameters, detonating network and blasting safety technology of the directional window, oriented window and load reducing slot. This paper provides the method for opening the overlarge arch oriented window, opening the special-shape load reducing slot and dense mesh safety net cross-multilayer coverage as well as comprehensive protection method for anti-flyrock splash and vibration reduction. Especially, the blast holes for opening the special-shape load reducing slot and the herringbone column are centralized at the bottom and top, which not only reduces the drilling workload, but also reduces the maximum detonating explosive amount of single section, and also reduces the safety protection workload.

Abstract: A three-dimensional nonlinear contact finite element method was employed in this paper to simulate the soil-pile interface behaviors of a pile group under complicated load in the Jiyang dike. The displacement at the soil-pile interfaces was particularly calculated. The computational results show that interaction mainly occurred in the bottom of the cap, and interaction development was restrained with the help of friction effect between pipes and surrounding soil. Moreover, the most unfavorable load combination is vertical uplift force together with horizontal force. As a result, potential channels of seepage flow could be formed at the location where cracks develop. Seepage field would be changed and the probability for seepage failure is increasing.

Abstract: System effectiveness and useful life of heat pump are directly affected by whether the design of ground heat exchanger is reasonable or not. The efficiency of heat exchanger has a close relationship with soil thermal conductivity coefficient and heat diffusivity, while soil moisture content affects soil thermal conductivity coefficient and soil temperature field. In this paper, we perform numerical simulation on CFD software. Then we study the soil temperature changes through field experiment in different soil moisture content on field experiment and finally obtained the relationships of the moisture content with the single U ground soil temperature field.

Abstract: One of the most important lessons learned from Alaska’s two major earthquakes in history is that the lateral spreading of frozen crust overlying on liquefiable soils generates significant lateral forces and have induced wide bridge foundation damages. When the ground crust is frozen, its physical properties including stiffness, shear strength and permeability will change substantially. A shake table test was conducted to study the soil-pile interaction in liquefiable soils with a frozen crust. Cemented sands were used to simulate the frozen crust and have successfully captured the mechanical parameters of frozen soil. With the 2011 Japan Earthquake as the main input motion, the mechanism of frozen soil-pile interaction in liquefiable soils is clarified. A brief discussion of the recorded data is analyzed. It turned out the existence of frozen soil is essential to consider in future seismic design of bridge foundations in cold regions.

Abstract: In this study, the grey system GM(1,1) and the geostatistical method are initially used to predict the land subsidence of the Yunlin area in the next five years. The Yunlin County Yuanchang Element School is taken as the site example when the stochastic poroelastic model is used in the study because there is a lack of data related to land subsidence. The verification results and prediction data of the stochastic poroelastic model and the grey system are displayed. The results show that the land subsidence in the next five years as calculated based on the data obtained from the monitoring wells is 0.3 m, while 0.31 m and 0.33 m are the prediction results from the stochastic poroelastic model and grey system model, respectively. This indicates the high precision of both models in predicting land subsidence. In order to simulate the effect of climate change on territorial planning, a prediction is made on the possible land subsidence for 2030, in this study. The prediction results are shows that by 25 January 2030, the stochastic poroelastic model shows a land subsidence of 1.01 m, while it is 1.68 m for the Grey System model. Because only the Changyuan Element School is taken as an observation station for the stochastic poroelastic model, the Grey System model is used to predict land subsidence for 2007 by the geostatistical method. The results show that land subsidence will mainly occur in the mid-western area of Yunlin and the western coastal area of Jianyi. To simulate the possible situations in the year 2030, four scene simulation models are proposed in this research, that is, adding 10% discharge, adding 20% discharge, subtracting 10% discharge, and subtracting 20% discharge. The results show the prediction on land subsidence for the year 2003 when add 10% discharge, subtract 10% discharge, add 20% discharge, and subtract 20% discharge, respectively. Land subsidence will occur mainly in the mid-western area of Yunlin and the western coastal area of Jiayi. The maximum land subsidence could reach up to 150 cm or so.

Abstract: The embankment soil arching effect of the composite foundation with sparse piles to control settlement is caused by the differential settlement between the embankment fill and the piles. So, the settlement is an important behaviour of the composite foundation. The effects of the height of embankment, the elastic modulus of geosynthetic and pile material, the stiffness of cushion and substratum, the pile cap and the distance of piles on the settlement are investigated using the computer code ABAQUS in this paper. The results indicate that the maximum settlement and differential settlement decrease with the elastic modulus of geosynthetic, the stiffness of cushion and substratum. The maximum settlement decreases and the differential settlement increases with the elastic modulus of pile material. At the same time, the differential settlement of the embankment surface decreases with the height of fill and there will be an equal settlement plane when the fill reaches certain height. In addition, the distance of piles has a more significant influence on settlement than the dimension of pile cap.

Abstract: Composite foundation influence parameters were discussed based on Drucker-prager elastic-plastic constitutive model in this paper. Contact element was adopted to simulate the interaction between pile and surrounding soil. Finite element software-ANSYS was applied to study and analyze the distribution and deformation of foundation.

Abstract: The composite foundation with sparse piles to control settlement has been used to rapid construction and strict deformation of the structure widely currently, which can enhance the efficient of load transfer and decrease the differential settlement used with the geosynthetic. Considering the confine of analytical solution and the traditional method with a changeless modulus of geosynthetic and pile, the effects of the height of fill, the elastic modulus of geosynthetic and pile material on the differential settlement, embankment soil arching effect and tensioned membrane effect etc. are investigated using the computer code ABAQUS in this paper. The results indicate that the modulus of geosynthetic and pile has a notable influence on the differential settlement and the arching effect, which should be considered in the design. At the same time, the maximum tension in geosynthetic occurs near the edge of the pile cap.

Abstract: The assignment is using Drucker-prager elastic-plastic constitutive model for vertical load to analysis the interface behavior between soil and pile materials. Through the parameter analysis, in actual projects, the pile diameter and properties of pile endpoint soil have definite influences upon stress distribution and deformation of foundation. The conclusions obtained here could be taken for reference by similar projects.