Time filter

Source Type

Qin X.,PLA Logistical Engineering University | Liu D.,Chongqing Bureau of Geology and Minerals Exploration | Song Q.,PLA Logistical Engineering University | Du C.,Chongqing Bureau of Geology and Minerals Exploration | Wang X.,PLA Logistical Engineering University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2017

A set of test system for studying the vertical infiltration in one-dimensional soil column under rainfall was developed. Four sets of tests were carried out to the unsaturated disturbed loess column under the different rainfall intensities. The time curves of the infiltration rate, the depth of the wetting front and the volumetric water content at the monitoring points were obtained.The formula of permeability coefficient was derived and the curve of the permeability coefficient varied with the matric suction of the disturbed loess was obtained. The rainfall intensity has great impact on the vertical infiltration in soil column. The infiltration rate equals to the rainfall intensity when the rainfall intensity is less than the minimum infiltration capacity of soil column. When the rainfall intensity is greater than the minimum infiltration capacity, the curve of infiltration rate can be divided into three stages, the non-compressive infiltration, the compressive infiltration and the saturated infiltration. The moment of occurrence of the dropsy point and the saturation point are different under different rainfall intensities, the greater the rainfall intensity, the earlier the dropsy point and saturation point appear, and the longer the stage of compressive infiltration. The permeability coefficient of the unsaturated remolded loess decreases exponentially with the increasing of matric suction. © 2017, Science Press. All right reserved.


Wei Y.,CAS Chengdu Institute of Mountain Hazards and Environment | Wei Y.,Sichuan Agricultural University | Wei Y.,University of Chinese Academy of Sciences | Zhou Z.,Chongqing Bureau of Geology and Minerals Exploration | Liu G.,CAS Chengdu Institute of Mountain Hazards and Environment
Journal of Mountain Science | Year: 2012

An understanding of the physical, chemical, and biological properties of a soil provides a basis for soil use and management. This paper reports the major physico-chemical properties and enzyme activities of the soils of Lhasa's main arable lands and the factors that influence these soil properties. Composite and core samples were taken from the three main arable soil types (alluvial soil, subalpine arable steppe soil, and subalpine arable meadow soil) and were analysed using standard methods. The bulk density and the ventilation porosity ratio of the soils were close to the recommended values for arable lands, and the dominant soil texture was sandy. The soil moisture release rates were arable steppe soil > alluvial soil > arable meadow soil. Soil organic matter content, Cation-Exchange Capacity (CEC), total and available nitrogen content, and catalase activity of the arable meadow soil were higher than those of the alluvial and the arable steppe soils, while soil pH in the arable meadow was lower. Most of the measured properties did not show a significant variance among these three soils. However, the measured indices (apart from the total potassium) indicate that there are notable differences among the three types of soil. The results implied that the utilisation patterns of the arable soil or human activities, such as tillage practices and fertiliser applications, have a substantial effect on the soil properties in this region. Our results suggest that the cultivation practices in the region have apparently positive impact on the soil organic matter, nutrient contents and bulk density probably due to the sound fertiliser management such as the applications of farmyard manure and chemical fertilisers. However, intense cultivation practices lowered the activity of most soil enzymes. The results demonstrate that the choice of soil management strategy had a significant impact on the soil physicochemical and biological properties in the region studied. © 2012 Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg.


Wu Y.,PLA Logistical Engineering University | Liu D.-S.,Chongqing Bureau of Geology and Minerals Exploration | Lu X.,PLA Logistical Engineering University | Song Q.-H.,PLA Logistical Engineering University
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Quantitative assessment of vulnerability for hazard bearing body is a difficult problem in landslide risk assessment. Taking impulse of landslide impact as disaster-causing strength index and taking whole shear force of building as disaster-resisting performance index, the quantitative assessment model for vulnerability of typical hazard bearing body is deduced. On this basis, considering the influence of randomness of movement parameter on vulnerability, the risk curve and maximum risk index are put forward so as to reflect the influence of uncertainty in process of landslide hazard. Influence of geometrical parameters of slope, space location and disaster-resisting performance of hazard bearing body on vulnerability are analyzed based on the model. Using risk index for case study and comparing with the existing methods, the quantitative assessment model can reflect the relationship between damage degree of hazard bearing body with each influential factor in two-dimension condition. The model provides a new way for quantitative assessment of vulnerability.


Wu Y.,PLA Logistical Engineering University | Liu D.-S.,Chongqing Bureau of Geology and Minerals Exploration | Lu X.,PLA Logistical Engineering University | Song Q.-H.,PLA Logistical Engineering University
Tumu Jianzhu yu Huanjing Gongcheng/Journal of Civil, Architectural and Environmental Engineering | Year: 2011

From the point of view of system theory, the landslide hazard system includes two subsystems: subsystem of hazard and subsystem of stricken. The consequence of landslide hazard is based on the interaction of these two subsystems, previous studies concenerate on evaluation of landslide stability. Hence, the study of a typical element at landslide risk is focused. And a method to calculate failure probability of typical element (frame structure) at landslide risk is discussed. Furthermore, the influences of both impact force and impact resistance-capability of element at risk on failure probability are analyzed, which shows that, for each elements at risk, the landslide impact area can be divided into absolutely dangerous zone, relatively dangerous zone and absolutely safety zone. In addition, with the condition that the structure failure probability is above 50%, as the variability of impact force increases, the structure failure probability decreases; with the condition that structure failure probability is below 50%, as the variability of impact force increases, the structure failure probability also increases.


Wu Y.,PLA Logistical Engineering University | Liu D.,Chongqing Bureau of Geology and Minerals Exploration | Li M.,PLA Logistical Engineering University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

Because of lack of internal energy dissipation law of landslide in the sliding and impact processes, we can not calculate the impact energy precisely. In order to solve this issue, the landslide models are designed and constructed according to the similarity principle. The measurement system of friction coefficient is made up of photoelectric sensor and electronic timer; and the measurement system of impact force is made up of dynamic soil pressure sensor and dynamic strain acquisition instrument. A measurement method of impact energy is proposed for the situations of perfect elastic collision and completely inelastic collision. The impact energies of landslide mass with the same weight and different particle sizes are tested. The results show that the impact energies decrease markedly with the particle size decreasing. And the reasons are that: the internal energy dissipation of landslide mass increase with the particle sizes decreasing; and the friction coefficient between the landslide mass and sliding path increases also, which adds to the friction energy dissipation. Based on the experiment analysis, two methods are proposed to calculate the impact energy, which provide reference for the further research, under the condition of unknown internal energy dissipation mechanism. The comparison with the existing method indicates that: for the landslides composed of all kinds of particle sizes, the result of method ignoring the inner energy dissipation is bigger than the proposed two methods; and the differences increase with the particle size decreasing.


Wu Y.,PLA Logistical Engineering University | Liu D.,Chongqing Bureau of Geology and Minerals Exploration | Lu X.,PLA Logistical Engineering University | Song Q.,PLA Logistical Engineering University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

Based on the situation that the quantitative degree for assessing the vulnerability of element at landslides risk is low, the quantitative assessment method of the vulnerability is discussed. Through analyzing the failure process of element at risk impacted by the landslide mass, it is considered that the impact energy translates into the deformation energy of element at risk gradually, which is caused by impact force work in process of element at risk impacted by the landslide mass. Because of plastic deformation, the deformation energy dissipates progressively; then it leads to the destruction and collapse of element at risk. Vulnerability is defined quantitatively as a function of impact kinetic energy and the deformation energy of structure. The quantitative function is deduced. Based on this function, the quantitative vulnerability assessment model for typical element at landslide risk is established by using energy method to calculate velocity of landslide debris for the simplified case. This quantitative model accords with the principle of landslide mechanism. It is a new way for vulnerability quantitative assessment.


Wu Y.-X.,PLA Logistical Engineering University | Liu D.-S.,Chongqing Bureau of Geology and Minerals Exploration | Song Q.-H.,PLA Logistical Engineering University | Song Q.-H.,Lanzhou University | Ou Y.-H.,PLA Logistical Engineering University
Yantu Lixue/Rock and Soil Mechanics | Year: 2013

The traditional strength reduction finite element method (SRFEM) is widely used in numerical analysis of slope stability. However, for the lack of considering geotechnical uncertainties, it still cannot be directly applied to the reliability analysis of slope stability, especially the dynamic stability problems. Thus, based on the SRFEM, the reliability analysis method of slope dynamic stability under seismic loading is proposed. In this method, the finite element limit analysis, dynamic analysis and reliability analysis are included to analyze the reliability problems of slope under seismic loading; and above process is realized in the numerical calculation program. For the traditional method, the acquirement of slope safety factor should be based on continuous manual pilot calculations, which makes batch processing impossible. But in the proposed method, above problem is solved through the improved slope dynamic failure criterion and the corresponding calculation program. The case study shows that the proposed method is significantly different from the general methods; it can relatively comprehensively reflect the dynamic characteristics of rock mass, the variability and correlation of material parameters. The results are closer to the reality. The proposed method not only widens the application scope of SRFEM, but also provides a new effective way for the reliability analysis of slope dynamic stability.


Wu Y.-X.,PLA Logistical Engineering University | Liu D.-S.,Chongqing Bureau of Geology and Minerals Exploration | Song Q.-H.,PLA Logistical Engineering University | Song Q.-H.,Lanzhou University | Ou Y.-H.,PLA Logistical Engineering University
Yantu Lixue/Rock and Soil Mechanics | Year: 2013

Currently, the calculation method of landslide-thrust and internal forces of anti-slide pile in essence belongs to the fixed value method. However, for the lack of considering geotechnical uncertainties, inadequate and excessive support problems for the anti-slide piles cannot be ignored. Thus, based on strength reduction of finite element method, the reliability analysis method of landslide-thrust and internal forces of anti-slide pile is proposed. In this method, the limit analysis, finite element analysis as well as reliability analysis are included. In the calculation process, 2-node beam element is used to simulate the stress condition of anti-slide pile; and the Latin hypercube sampling (LHS) method is used for reliability calculation; and above process is realized in the numerical calculation program. Landslide-thrust and internal forces of anti-slide pile are statistically analyzed; and function distributions can be achieved. With the control values of a given failure probability, the design values of landslide-thrust and internal forces can be accurately determined. Typical example analysis shows that the proposed method is significantly different from the general methods; it can reflect the slope present situation, overall characteristics and the variability of material parameters; and the results are closer to the reality.


Wu Y.,PLA Logistical Engineering University | Lu X.,PLA Logistical Engineering University | Liu D.-S.,Chongqing Bureau of Geology and Minerals Exploration | Zhu J.-K.,PLA Logistical Engineering University
Chongqing Daxue Xuebao/Journal of Chongqing University | Year: 2012

Small and medium landslides are widely distributed, the prediction mainly relies on the monitoring and controlling systems executed by the masses. The advantages and disadvantages of various stability assessment methods are compared. The engineering analogy method accords with the requirements for small and medium landslide assessment. A method is illustrated based on Fisher discrimiant function to cope with the small and medium potential landslide stability assessment. The impact factors of landslides is explored with the historical data. The stability is taken as a multi-dimensional statistical variable and project into one-dimensional straight line. Distance discriminant method is used to construct a classification criterion. The applicability of this method is explored, and assessed the landslides in Chongqing Wulong by this method. The results show that accuracy of this method is about eighty percent. This method is suitable for the city of Chongqing or other areas with the similar geological environment.


Wu Y.,PLA Logistical Engineering University | Liu D.-S.,Chongqing Bureau of Geology and Minerals Exploration | Lu X.,PLA Logistical Engineering University | Song Q.-H.,PLA Logistical Engineering University
Yantu Lixue/Rock and Soil Mechanics | Year: 2010

Property risk assessment for single landslide is the foundation of prevention and mitigation measures. Since we can not evaluate the vulnerability of elements at risk quantitatively, property risk assessment of single landslide becomes hard to achieve accuracy. In light of the typical elements at risk, a quantitative assessment model for property risk caused by single landslide is presented, which defined by probability of slope fall, reliability of structure and the value of elements at risk. Avoiding the vulnerability evaluation, assesses the property risk from a new point of view. Through the research, it is shown that the model can reflect the influence of landslide factors exactly, and provides a new way to assess property risk quantitatively for single landslide. A new conception of safety zone that based on this model is introduced. For each one of elements at risk, the impact area of single landslide can be divided into dangerous zone, relatively dangerous zone and safety zone.

Loading Chongqing Bureau of Geology and Minerals Exploration collaborators
Loading Chongqing Bureau of Geology and Minerals Exploration collaborators