Experimental Investigation on the Movement of Soil and Piles in Transparent Granular Soils     

Feng Yin  Yang Xiao  Hanlong Liu  Hang Zhou  Jian Chu 《Geotechnical and Geological Engineering》2018,36(2):783-791

In order to visually observe the displacement characteristics of internal soil, model tests on the penetration of six flat-ended piles in synthetic transparent soil were carried out. The granular-soil particles were registered by laser speckles, thus the penetration process of the piles was visualized. The movement of pile-soil interaction was determined by comparing the images before and after penetrations. Based on the test results, the vertical and horizontal displacement of the granular caused by a sequence of jacked piles was discussed. The sheltering effect of the adjacent piles during the penetration of the follow-up pile was analyzed. The responses of the granular soils during the penetration of piles were discussed, and test data was compared with DEM analyses. The pile heave at different stages of the penetration and the ground uplift at different positions were evaluated and compared.  相似文献   

丽江观测站1.8米望远镜自适应光学系统性能初步理论估计     

陈京元  和成  张定稳  和福瑞  和汉龙  熊耀恒 《天文研究与技术》2013,(3):308-320

为了探讨丽江1.8 m自适应光学望远镜在天文或天体物理研究领域的可能应用,使用误差基本标度理论对其性能进行了初步的理论分析。结果表明,一般观测条件下,系统分辨力可以达到近似衍射极限。同时对在其上配置激光导星系统后可获得的性能进行了预测,结果表明,激光导星自适应光学系统将大幅度提高系统的天空覆盖率。  相似文献   

Quasi-plane-hypothesis of strain coordination for RC beams seismically strengthened with externally-bonded or near-surface mounted fiber reinforced plastic     

Ren Zhenhua  Zeng Xiantao  Liu Hanlong  Zhou Fengjun 《地震工程与工程振动(英文版)》2013,12(1):67-76

The application of fiber reinforced plastic(FRP),including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement(EBR) and near-surface mounted(NSM) strengthening techniques.This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC beam.Since there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height(h 0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of the FRP and steel rebar satisfies the equation:ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.  相似文献   

Particle breakage and deformation of carbonate sands with wide range of densities during compression loading process     

Yang Xiao  Hanlong Liu  Qingsheng Chen  Qifeng Ma  Yuzhou Xiang  Yingren Zheng 《Acta Geotechnica》2017,12(5):1177-1184

In this technical note, evolutions of the particle size distribution, particle breakage, volume deformation and input work of carbonate sands with varying relative densities were investigated through performing a series of one-dimensional compression tests. Loading stress levels ranged from 0.1 to 3.2 MPa. It was found that the initial relative density could greatly affect the magnitude of particle size distribution, particle breakage, volume deformation and input work. Particularly, it was observed that the specimen at a lower relative density underwent much more particle breakage than that at a higher relative density. This could be attributed to the change of the coordination number with the initial density. However, a unique linear relationship between the particle breakage and input work per volume could be obtained, which is independent of the initial relative density.  相似文献   

Time-domain solution for transient dynamic response of a large-diameter thin-walled pipe pile     

Ding Xuanming  Liu Hanlong  Chu Jian  Cheng Ke 《地震工程与工程振动(英文版)》2015,14(2):239-251

The propagation of stress waves in a large-diameter pipe pile for low strain dynamic testing cannot be explained properly by traditional 1D wave theories. A new computational model is established to obtain a wave equation that can describe the dynamic response of a large-diameter thin-walled pipe pile to a transient point load during a low strain integrity test. An analytical solution in the time domain is deduced using the separation of variables and variation of constant methods. The validity of this new solution is verifi ed by an existing analytical solution under free boundary conditions. The results of this time domain solution are also compared with the results of a frequency domain solution and fi eld test data. The comparisons indicate that the new solution agrees well with the results of previous solutions. Parametric studies using the new solution with reference to a case study are also carried out. The results show that the mode number affects the accuracy of the dynamic response. A mode number greater than 10 is required to enable the calculated dynamic responses to be independent of the mode number. The dynamic response is also greatly affected by soil properties. The larger the side resistance, the smaller the displacement response and the smaller the refl ected velocity wave crest. The displacement increases as the stress waves propagate along the pile when the pile shaft is free. The incident waves of displacement and velocity responses of the pile are not the same among different points in the circumferential direction on the pile top. However, the arrival time and peak value of the pile tip refl ected waves are almost the same among different points on the pile top.  相似文献   

Grain crushing in geoscience materials-Key issues on crushing response,measurement and modeling:Review and preface     

Yang Xiao  Chandrakant SDesai  Ali Daouadji  Armin WStuedlein  Hanlong Liu  Hossam Abuel-Naga 《地学前缘(英文版)》2020,(2):363-374

Grain crushing is commonly encountered in deep foundation engineering,high rockfill dam engineering,railway engineering,mining engineering,coastal engineering,petroleum engineering,and other geoscience application.Grain crushing is affected by fundamental soil characteristics,such as their mineral strength,grain size and distribution,grain shape,density and specimen size,and also by external factors including stress magnitude and path,loading rate and duration,degree of saturation,temperature and geochemical environment.Crushable material becomes a series of different materials with the change in its grading during grain crushing,resulting in a decrease in strength and dilatancy and an increase in compressibility.Effects of grain crushing on strength,dilatancy,deformation and failure mechanisms have been extensively investigated through laboratory testing,discrete element method(DEM)modelling,Weibull statistics,and constitutive modelling within the framework of the extended crushing-dependent critical state theory or the energy-based theory.Eleven papers summarized in this review article for this special issue addressed the above issues in grain crushing through the advanced testing and modelling.  相似文献   

Stability analysis of soil slopes based on strain information     

Wang  Zhenyu  Zhang  Wengang  Gao  Xuecheng  Liu  Hanlong  Böhlke  Thomas 《Acta Geotechnica》2020,15(11):3121-3134

Acta Geotechnica - The failure of engineering slopes may cause great property loss and casualties, against which the slope deformation monitoring and instrumentation are needed. To investigate the...  相似文献   

Efficient reliability analysis of earth dam slope stability using extreme gradient boosting method     

Wang  Lin  Wu  Chongzhi  Tang  Libin  Zhang  Wengang  Lacasse  Suzanne  Liu  Hanlong  Gao  Lei 《Acta Geotechnica》2020,15(11):3135-3150

Acta Geotechnica - Reliability analysis approach provides a rational means to quantitatively evaluate the safety of geotechnical structures from a probabilistic perspective. However, it suffers...  相似文献   

Influences of reservoir water level drawdown on slope stability and reliability analysis     

Xuecheng Gao  Hanlong Liu  Wei Wang  Zhenyu Wang 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2019,13(2):145-153

To investigate the influences of reservoir water level drawdown on slope stability, a series of numerical simulations were carried out to examine the impacts of slope angle, slope permeability and water drawdown speed on the pore water pressure (PWP) change during seepage, as well as the factor of safety (Fs) of the slope. Based on the numerical results, an estimation model relating the factor of safety to the influential factors mentioned above was developed. The model expression indicates that there are interaction effects between the slope angle, the drawdown speed and the slope permeability, with regard to the influences on slope stability. Furthermore, in view of the uncertainty characteristics of the slope permeability, reliability assessment was performed to examine the influences of those key parameters mentioned above on the probability of slope failure.  相似文献   

Particle breakage and energy dissipation of carbonate sands under quasi-static and dynamic compression     

Xiao  Yang  Yuan  Zhengxin  Chu  Jian  Liu  Hanlong  Huang  Junyu  Luo  S. N.  Wang  Shun  Lin  Jia 《Acta Geotechnica》2019,14(6):1741-1755

Acta Geotechnica - Quasi-static and dynamic compression tests are conducted on carbonate sand using a Material Testing System and a modified split Hopkinson pressure bar, respectively. The particle...  相似文献