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Chen C.,Xian University of Technology | Jiang X.,Zhengzhou Thermal Power Corporation | Su T.,Beijing Aerospace Geotechnical Engineering Institute Co. | Jin J.,Xian University of Technology | Li W.,Xian University of Technology
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2014

A series of unconfined compression tests were conducted on compacted loess samples with different structures at the same dry density and experimental water content. Based on the stress-strain curves of unsaturated and saturated compacted loess, the initial quantitative parameter was defined to describe the maximum overall structure potential before the start of the structural damage of the compacted loess. The influence of different structures caused by the change of molding water content on the stress-strain and strength characteristics as well as the structural parameter was investigated for the compacted loess with different experimental water contents. The results indicated that the molding water content affected the structure and the unconfined compressibility of unsaturated compacted loess, but had little influence on that of saturated compacted loess. The degree of influence decreased with the increase of water content. The plastic limit was found to be the critical value. When the experimental water content was smaller than the plastic limit, the influence was greater. The unconfined compressive strength and the initial structural parameter increased notably with the increase of the molding water content at the same experimental water content and decreased significantly with the increase of experimental water content at the same molding water content. The group of curves describing the relationships of the unconfined compressive strength versus the molding water content and the experimental water content was normalized into a nonlinear relationship with the initial structural parameter. The normalized nonlinear relationship described the influence of molding water content and experimental water content on the structure of compacted loess. Together with the grain size and the density, it described reasonably the mechanical properties of compacted soil. ©, 2014, Academia Sinica. All right reserved. Source

Kong L.G.,Zhejiang University | Chen R.P.,Zhejiang University | Wang S.H.,Beijing Aerospace Geotechnical Engineering Institute Co. | Chen Y.M.,Zhejiang University
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2015

This paper reports two 3 × 3 pile group tests in saturated silt laterally loaded at eccentric distances of 6D and 11D. The model piles were 0.114 m in diameter and 5.95 m in length. The objectives of the tests are to investigate (1) the response of the pile group subjected to eccentric lateral loading and the influence of load eccentricity; and (2) the internal forces mobilized in the piles and their contributions to resisting the applied lateral loads and torques. The results of the model tests indicate that the lateral resistance of the pile group decreased significantly with eccentricity. The lateral resistance of the pile group with an eccentric distance of 6D was 1.5 times that with an eccentric distance of 11D at a horizontal displacement of 50 mm at the center of the pile cap. The mobilized pile-head shear forces as well as the bending moments and horizontal displacements in the piles differ significantly in both magnitude and direction. The shear resistances of the piles contributed to resisting both the applied lateral loads and torques. Different twist centers were found in the 3 × 3 pile group for different load eccentric distances. The distances of the twist center to the pile cap center were 9 and 3.7D in the tests with eccentric distances of 6 and 11D, respectively. © 2015 American Society of Civil Engineers. Source

Ping J.F.,Beijing Aerospace Geotechnical Engineering Institute Co. | Ping J.F.,China University of Geosciences | Ze G.Z.,Beijing Aerospace Geotechnical Engineering Institute Co. | Gang Y.D.,Beijing Aerospace Geotechnical Engineering Institute Co.
Proceedings of the 3rd Academic Conference of Geology Resource Management and Sustainable Development, GRMSD 2015 | Year: 2015

Geothermal resources, which have features such as clean and efficiency, are increasingly widely exploited and utilized. Proven ten geothermal fields in Beijing area stocked with rich medium-low temperature geothermal resources. Under the "Green Beijing" development strategy of urban construction, most geothermal resources applications in Beijing area are direct uses, including heating, bathing, health, tourism, agriculture and cultivation. Shallow geothermal resources development based on heat pump technology has been growing rapidly. Entering the 21st century, to alleviate the water level problem, geothermal reinjection in Beijing has been vigorously enhanced. In order to promote the geothermal resources to grow in a sustainable manner and strengthen the management of geothermal resources, it is recommended to encourage large-scale development and strengthen the management of geothermal resources. In addition, to make contributions to construct and develop of "Green Beijing", geothermal development should follow the principles of environmental protection, rational distribution, unified planning and scientific utilization. Source

Zhang W.,Beijing Aerospace Geotechnical Engineering Institute Co. | Zhang W.,Yunnan Aerospace Engineering Geophysical Detecting Co. | Li Y.,Beijing Aerospace Geotechnical Engineering Institute Co. | Wang Z.,Beijing Aerospace Geotechnical Engineering Institute Co.
Jiefangjun Ligong Daxue Xuebao/Journal of PLA University of Science and Technology (Natural Science Edition) | Year: 2014

To break through the contradiction between the investigation depth and identification of ground penetrating radar (GPR) with low frequency antenna, and meet the need of refinement geophysical prospecting in shallow underground engineering, radar signal collected by normal low frequency antenna was post-processed based on the spectral energy analysis method. The recognition ability of the radar echo is effectively improved through frequency intensity analysis of the investigated target medium body, and the investigation depth is 2-3 times deeper than that of the normal radar signal processing method. Combined with the detecting example of the disturbance influence of the collapsed surrounding rock in the tunnel, large-scale investigation depth reaches 100 m by using 100 MHz low frequency antenna and signal post-processing technology of spectral energy analysis, and the engineering problem of large-scale investigation with GPR is solved preliminarily. Source

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