Time filter

Source Type

Zhang C.L.,Chang'an University | Zhang C.L.,Open Research Laboratory of Geotechnical Engineering | Li T.L.,Hong Kong University of Science and Technology | Li P.,Hong Kong University of Science and Technology | And 2 more authors.
14th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering | Year: 2011

Loess landslides are the most popular occurred geological hazard in Chinese loess area. They are triggered by the four agents of earthquakes, rainfalls, irrigations and engineering activities. Kinetically, they can be divided into four types: slow transitional slides, rapid long run out slides, quick collapse slides and rapid flow slides. The mechanism of the landslide movement is controlled by the pore water pressure on the sliding surface. The slow transitional slide is that the slip mass slid on an impermeable slip bed, such as red clay or bedrock, where the pore pressure at the slip surface neither generate nor dissipate. The long run out slide is that the slip mass slid on a saturated loose ground, where the pore water pressure caused by un-drained loading and un-drained shear inside the ground is much higher than that inside the slip mass, therefore the shearing may take place in the ground. The collapse slide is that the less saturated slip mass slid on a less saturated or dry ground, where the pore water pressure on the slip surface decrease, even creating a negative water pressure because of water dissipation. The quick flow slide is that the saturated slip mass slid on a less saturated or dry ground, which causes a lower or even negative pore pressure, a film of liquid soil is stuck on the ground and the sliding occur in the slip mass.


Chen W.,Chang'an University | Chen W.,Key Laboratory of Western Chinas Mineral Resource and Geological Engineering | Chen W.,Open Research Laboratory of Geotechnical Engineering | Zhao F.,Chang'an University | And 2 more authors.
Applied Mechanics and Materials | Year: 2013

A linear viscoelastic plastic creep model of mica-quartzose schist is established by using the method of establishing combined-linear-component model based on triaxial creep test. The micro-structural changes of mica-quartzose schist during triaxial creep process are observed by using the scanning electron microscope test, based on that, the relation of macro-stress and macro-strain with porosity and damage variable are established through statistical damage theory and simplified mechanical model respectively, the creep damage variable is obtained by further derivation on the basis of above study. The creep damage variable is simplified according to the whole creep process curve, substitutes the simplified creep damage to the estabilished linear viscoelastic plastic creep model of mica-quartzose schist, considering the change of modulus and viscosity during creep process, a viscoelastic plastic damage model of mica-quartzose schist is established. The model parameters are got by segment fitting, the good consistency of the test curves and the fitted curves shows the right and reasonable of the creep model, it also shows that the model can well describe the nonlinear accelerated creep stage. Sensitivity analysis shows that parameter m has greater influence on the accelerated creep deformation than parameter a. © (2013) Trans Tech Publications, Switzerland.


Chen W.L.,Chang'an University | Chen W.L.,Key Laboratory of Western Chinas Mineral Resource and Geological Engineering | Chen W.L.,Open Research Laboratory of Geotechnical Engineering | Zhao F.S.,Chang'an University | And 2 more authors.
Applied Mechanics and Materials | Year: 2012

Firstly, the creep curves of mica-quartzose schist are obtained through the triaxial creep test, the triaxial creep characteristics are found out by analyzing the creep curves. Secondly, a linear viscoelastic model is established by using model theory, a viscoplastic model is established by using empirical formula, added the above two model, a non-linear viscous elastic-plastic creep model of mica-quartzose schist is obtained. Lastly, the creep model parameters are got by data fitting, the good consistency of the test curves and the theoretical curves show the right and reasonable of the creep model. The non-linear viscous elastic-plastic creep model established can well describe the accelerated creep of mica-quartzose schist. © (2012) Trans Tech Publications, Switzerland.


Zhang C.,Chang'an University | Zhang C.,Open Research Laboratory of Geotechnical Engineering | Zhang Y.,Chang'an University | Zhang X.,Henan Institute of Engineering | And 2 more authors.
Advanced Materials Research | Year: 2012

Ningde nuclear power plant in Fujian province is one of the national key construction projects of nuclear power, in order to insure the smooth progress of construction project, it needs to assess the rock slope stability which lies in the southeast of the living area. On the base of the rock architectural feature, the qualitative analysis, the three-dimensional limit equilibrium and the three-dimensional finite element are adopted to analyze the stability of the slope. The result of the qualitative analysis shows that most of the slope is stable, and part of it may fail after excavation. The result of the three-dimensional limit equilibrium and the three-dimensional finite element both illustrate that the slope is stable after excavation with slope ratio 1:0.25, 1:0.50 and 1:0.75, and the stability factor rises with the decreasing of the slope ratio. At last, according to the above computing result, the 1:0.50 or the minor value is suggested to be adopted as the design slope ratio to excavate the slope.


Li P.,Chang'an University | Li P.,Open Research Laboratory of Geotechnical Engineering | Su S.-R.,Chang'an University | Huang Y.,Chang'an University | And 3 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2015

This paper investigates the formation mechanism and deformation law of earthquake-induced shattering-sliding collapses induced by studying the collapse at K70+340-K70+388 of S303 highway from Wolong to Balangshan in Sichuan province, using the combination of geomechanical method and the simulation of discrete element method UDEC. It is shown that: these collapses mainly occur in bedding slopes with steep joints; the seismic wave leads to a tensile-shear failure to the slope; and the tensile stress at dome of the slope is greater than that inside the slope; deformation induced by seismic force is found to be faster and greater at the upper and dome of the slope than that at the lower and interior of slope; the higher amplitude of seismic acceleration is, the greater slope dynamic response is, and the larger displacement of collapse mass. The failure process of shattering-sliding collapse can be divided into six stages, 1) rock mass damage and tensile fractures formatting under earthquake; 2) tensile fractures expansion and coalescence of weak slip plane; 3) the whole slump-mass scattered and local rocks slip; 4) local rocks fall, ejection, mass ejection and tumble; 5) rock mass fall, ejection, mass ejection and tumble; 6) slump-mass tends to be stability. Therefore, this research provides not only a new method for geological hazard analysis, but also a significant guide to disaster prevention and mitigation in earthquake region. © 2015, Academia Sinica. All right reserved.


Zhang J.,Chang'an University | Zhang J.,Open Research Laboratory of Geotechnical Engineering | Hao R.,Chang'an University | Zhang Q.,Chang'an University | And 2 more authors.
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2014

Covariance function fitting for stochastic signal is a key problem for collocation. In the process of covariance function estimation, we often assume stochastic signals with the characteristic of isotropic, but anisotropic is more generally. Combined the expressions of error component in different directions, a method of covariance function fitting based on anisotropic is given. Further, adaptive collocation, which constructed by variance component estimations can adjust the contribution to model parameters by observation errors and stochastic signals and weaken the affect leading by their uncertainty, is proposed and applied in missing InSAR data fitting. A practical example shows that collocation can well supply the missing data, and adaptive collocation based on anisotropic covariance function can give higher accuracy in missing data fitting.


Fan W.,Chang'an University | Fan W.,Key Laboratory of Western Chinas Mineral Resources and Geological Engineering | Fan W.,Open Research Laboratory of Geotechnical Engineering | Xiong W.,Chang'an University | And 6 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

By use of a 1:25 model to simulate one section of the ground fissure in Xi'an, the effect of ground fissure activities on segmental lining is studied. The results indicate that each segment of lining can satisfy the quantitative unattached deformation and there is very small effect between each segment lining, so it can adapt to the ground fissure surroundings. When a fissure moves, the earth pressure at the lining top at the depth of 10 cm of two segments in the hanging wall and one segment in the footwall near the fissure decreases. The earth pressure at the lining bottom at the depth of 5 cm of one segment in the hanging wall near the fissure decreases, but that in the footwall increases. The top and bottom of two segment linings near the fissure in the hanging wall are longitudinally pressed. The top of one segmental lining in the footwall is pulled, but its bottom is pressed. Both sides of the lining near the fissure in the hanging wall are pressed, and the effect is smaller in the footwall. The main failure mode for the linings is that sidewall suffers hoop extrusion, which often occurs in the hanging wall, especially near the fissure. The secondary fissures in the soil do not develop, and they only appear on the top of the hanging wall near the fissure and inside the soil of the footwall. The soil is pulled and sheared to form the fissure.


Deng L.-S.,Chang'an University | Fan W.,Chang'an University | Fan W.,Key Laboratory of Western Chinas Mineral Resources and Geological Engineering | Fan W.,Open Research Laboratory of Geotechnical Engineering | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

Based on the distribution and movement of ground fissures and the condition of No. 2 metro tunnel in Xi'an, a geological model is established. Through the numerical analysis of finite element model, the protection range of the metro tunnel crossing ground fissures and its most dangerous section are confirmed by analyzing its deformation and stress states, and then, the distribution characteristics of surrounding rock pressure are studied so as to provide a basis for simplification of the model to calculate the stress of the metro tunnel crossing ground fissure. The results show that the main protection range of deformation and stress of the metro tunnel is from the location at the upper wall 40 m to that at the lower wall 30 m away from the fissure, that the most dangerous section is mainly distributed at the place of the ground fissure with a distance of 15~20 m at both sides, and that the structure in the range of 15 m away from the fissure at both sides suffers the maximum shear stress. The vertical pressure above the metro tunnel at the upper wall near the fissure is greater than that at the bottom, and the latter may be ignored. Therefore, the section of the metro tunnel crossing the fissure should be regarded as a beam which is sustained at the two sides of the subsiding area, and the vertical pressure of wall rock used to confirm the flexural torque produced by the activity of ground fissures should be calculated by the theory of stress transfer.


Zhang C.,Chang'an University | Zhang C.,Open Research Laboratory of Geotechnical Engineering | Huang S.,China Communications Construction Company Ltd. | Guo J.,Chang'an University | Li T.,Chang'an University
Advanced Materials Research | Year: 2012

In this paper, the deformations and the stresses of surrounding rock of Jijiata tunnel, Liulin County, Shanxi Province, are all computed before reinforcement and after reinforcement, through the 3D numerical simulation. According to the computing result, before reinforcement, the computing result of the lateral displacements of the surrounding rock is consistent with the field measurement result. The maximum principle stress and the minimum principle stress are all less than the strength of the surrounding rock supporting, and this will not cause material damage so as to structural damage. But, since the tension stress is higher than the strength of the junction of tunnel arch and tunnel upright wall, this leads the larger deformation and the failure of the junction. After reinforcement, through the steel arch and the lock pin bolt's enhanced role, the lateral displacement of the tunnel can be constrained effectively, the maximum principle stress and the minimum principle stress can be less than the strength of the surrounding rock supporting, and the tension stress can also be less than the strength of the junction. All the structures are all stable after reinforcement. Thus, this method should be selected as the proper method to reinforce the tunnel.


Zhang C.,Chang'an University | Zhang C.,Open Research Laboratory of Geotechnical Engineering | Lei X.,Chinese Research Institute of Highway | Li T.,Chang'an University | Li P.,Chang'an University
Advanced Materials Research | Year: 2011

On the base of the equilibrium of the whole force equilibrium, the whole moment equilibrium of the slope, and the force equilibrium of the differential column, this paper provides a general form of the 3D limit equilibrium which includes three equations. Through these equations and each assumption of the classical methods, their analytic forms can be gotten. Thus, not only the computation quantities of the classical method can be decreased greatly, but also the programming of them become very easy, and the computation efficiency also can be developed. At last, through the example in Zhang Xing's paper and the analytic forms of the classical methods, this paper analyzes the effect of the sliding body width, the shearing strength parameters and the shearing force direction on the safety factor. © (2011) Trans Tech Publications, Switzerland.

Loading Open Research Laboratory of Geotechnical Engineering collaborators
Loading Open Research Laboratory of Geotechnical Engineering collaborators