A revised solution for the horizontal vibration of an end‐bearing pile in viscoelastic soil          下载免费PDF全文

Hanlong Liu  Changjie Zheng  Xuanming Ding  George P. Kouretzis  Scott W. Sloan 《国际地质力学数值与分析法杂志》2016,40(13):1890-1900

This note presents a new method to derive closed‐form expressions describing the horizontal response of an end‐bearing pile in viscoelastic soil subjected to harmonic loads at its head. The soil surrounding the pile is assumed as a linearly viscoelastic layer. The propagation of waves in the soil and pile is treated mathematically by three‐dimensional and one‐dimensional theories, respectively. Unlike previous studies of the problem, the formulation presented allows the governing equations of the soil to be solved directly, eliminating the need to introduce potential functions. Accordingly, the dynamic response of the pile is obtained by means of the initial parameter method, invoking the requirement for continuity at the pile–soil interface. It is demonstrated that the derived compact solution matches exactly an existing solution that utilises potential functions to formulate the problem. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

A modified analytical solution of soil stress distribution for XCC pile foundations     

Yaru Lv  Hanlong Liu  Charles W. W. Ng  Anthony Gunawan  Xuanming Ding 《Acta Geotechnica》2014,9(3):529-546

X-section cast-in-place concrete pile (XCC pile) is a new type of pile foundation, which has an X-shaped cross section. Compared to the traditional circular pile of the same cross-sectional area, the bearing capacity of an XCC pile is higher due to increased cross-sectional perimeter. Since Geddes solution is based on St. Venant’s principle, leading to the results independent of the cross-sectional geometry and size, large differences are induced when estimating the soil stress distribution for XCC pile foundations. This paper derives a modified analytical solution, which is dependent on the cross-sectional geometry of XCC pile, from Geddes solution. Validation of this modified solution was conducted through three-dimensional numerical analysis and proven more suitable for XCC pile foundations. Parametric study on three geometrical parameters is conducted using this modified solution. The results indicate that the stress in founding soil due to skin friction decreases with increasing pile radius and central angle of concave, but increases with increasing length of flat side. The stress due to end-bearing decreases with increasing pile radius and length of flat side, but increases with increasing central angle of concave. From the parametric studies, the recommended dimensions of XCC pile radius, length of flat side, and central angle of concave are recommended ranges from 200 to 600 mm, 30 to 60 mm, and 90° to 150°, respectively.  相似文献   

Microscopic investigation on bonding fracture of biocemented sand from novel in situ brazil splitting tests     

Ma  Guoliang  Fang  Qingyun  Xiao  Yang  Chu  Jian  Liu  Hanlong 《Acta Geotechnica》2022,17(11):4935-4951

Acta Geotechnica - The failure mechanism of biocemented sand has been largely speculated based on scanning electron microscopy images of biocemented sand after mechanical tests. However, some...  相似文献   

Enhancing splitting tensile strength of biocarbonated reactive magnesia-based sand using polypropylene fiber reinforcement     

Zhang  Dong  Zhang  Wengang  Yang  Yang  Liu  Hanlong  Cheng  Liang 《Acta Geotechnica》2022,17(10):4761-4768

This short communication investigates the involvement of polypropylene fibers in the biocarbonated reactive magnesia cement mixes to improve the splitting tensile strength of sand for soil improvement. By varying the RMC content (5 and 10% by weight of sand) and fiber content (0, 0.5, and 1% by weight of sand), a suitable mix design was determined. The test results showed that the peak tensile strength of biocarbonated RMC-based sand samples with an optimum fiber content of 1% could improve by more than 4 times compared to the biocarbonated sand without fiber reinforcement. This was attributed to the generation of hydrated magnesium carbonates with the microbially induced CO₂/carbonate process, bonding the fiber–matrix and eliminating the brittleness, consequently enhancing the tensile ductility of biocarbonated sand.

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Finite element analyses of negative skin friction on a single pile   总被引：1，自引：0，他引：1  

Jinyuan Liu  Hongmei Gao  Hanlong Liu 《Acta Geotechnica》2012,7(3):239-252

This paper presents finite element analyses of negative skin friction on a single pile under various conditions. Negative skin friction is a common problem if a pile is designed in a highly compressible soil. There are two most important parameters in estimating the load caused by negative skin friction: (1) the distribution and magnitude of skin friction and (2) the location of the neutral plane. The neutral plane is the location where the pile and soil settle the same amount or have no relative displacement. Negative skin friction is a very complex phenomenon influenced by many factors. In this paper, a two-dimensional axisymmetric model is built in the finite element program, ABAQUS. The model is first verified with a known case history. A systematic parametric analysis is performed to investigate the influence on both the neutral plane and the magnitude and distribution of negative skin friction along the pile length of various influencing factors, including the consolidation time, the properties of pile/soil interface, the lateral earth pressure coefficient, pile-soil limiting displacement, the intensity of surcharge, and soil stiffness. Based on the analyses, it is found that the location of the neutral plane is significantly influenced by the consolidation time and the stiffness of bearing layer. The distribution and magnitude of negative skin friction is influenced mainly by the pile/soil interface, soil compressibility, and the surcharge intensity. Based on the field measurements from literature and this investigation, a simple design procedure is proposed for estimating the pile load caused by negative skin friction.  相似文献   

Occurrence and composition of sphene from eastern fold belt, Mount Isa Inlier, Cloncurry, northwestern Queensland, Australia     

应汉龙  普传杰 《中国地球化学学报》2005,24(1):18-27

Sphene is very common in rocks including albitized granite, dioritic porphyrite, calcsilicate rock and breccia from the eastern fold belt of Mount Isa Inlier, Cloncurry. Two stages of sphenes are present in these rocks. First-staged sphene is relatively fine, euhedral, some grains show round or patchy zoning; second-staged sphene is relatively large, anhedral to subhedral, some grains show patchy zoning;both possibly contain rutile, ilmenite and magnetite inclusions. All sphenes are of low-Al type. The second-staged sphene has lesser Fe apfu than the first-staged sphene. Light-color part of the sphene has bigger Fe apfu than the dark-color part, as observed on one individual grain of sphene with patchy zoning, the average Xro of the sphene with patchy zoning is greater than that of the sphene without patchy zoning. Because the sphenes are taken from different types of rocks, Si, Ti, and Al have variable relations with F OH apfu. Si and Ti are not correlated with OH F in all analyzed samples ; Fe is correlated with OH F in the sphene just from granite and dioritic porphyrite; Al is correlated with OH F in the sphene fromgranite and breccia and is not correlated with OH F in the sphene from the dioritic porphyrite and calcsilicate rocks. The first-staged sphenes were possibly formed in the processes of magmatism and metamorphism. The second-staged sphenes were formed as a result of the breakdown of hornblendes and biotites in the process of Na (Ca) -metasomatism.  相似文献   

四川西部现代热泉型金矿化的发现和初步研究   总被引：3，自引：0，他引：3  

王登红付小方  应汉龙 《地质论评》2003,49(3):311-315

四川西部现代热泉分布广泛，但以往对于其含金性没有研究资料。本文报道了对四川西部巴塘县热坑一带、理塘县热水塘一带及康定县木格错一带现代热泉及其水热活动产物中含金性初步调查的结果，发现热水本身携带有金，泉华堆积物中钙质部分含金较低、铁硅质部分含金较高，以强烈硅化的蚀变围岩含金最高，整体矿化水平与云南腾冲热泉型金矿相似。建议在三江地区对现代热泉的含矿性进行专门调查，并注意对深部矿化情况的调查研究。  相似文献   

The detailed particle breakage around the pile in coral sand     

Peng  Yu  Liu  Hanlong  Li  Chi  Ding  Xuanming  Deng  Xin  Wang  Chunyan 《Acta Geotechnica》2021,16(6):1971-1981

Acta Geotechnica - Detailed particle breakage adjacent to a pile has great influence on the settlement and bearing capacity of a pile foundation. Before the pile test, coral sand was divided into...  相似文献   

Study of the seismic performance of hybrid A-frame micropile/MSE (mechanically stabilized earth) wall     

Yumin Chen  Zhichao Zhang  Hanlong Liu 《地震工程与工程振动(英文版)》2017,16(2):275-295

The Hybrid A-Frame Micropile/MSE(mechanically stabilized earth) Wall suitable for mountain roadways is put forward in this study: a pair of vertical and inclined micropiles goes through the backfill region of a highway MSE Wall from the road surface and are then anchored into the foundation. The pile cap and grade beam are placed on the pile tops, and then a road barrier is connected to the grade beam by connecting pieces. The MSE wall's global stability, local stability and impact resistance of the road barrier can be enhanced simultaneously by this design. In order to validate the serviceability of the hybrid A-frame micropile/MSE wall and the reliability of the numerical method, scale model tests and a corresponding numerical simulation were conducted. Then, the seismic performance of the MSE walls before and after reinforcement with micropiles was studied comparatively through numerical methods. The results indicate that the hybrid A-frame micropile/MSE wall can effectively control earthquake-induced deformation, differential settlement at the road surface, bearing pressure on the bottom and acceleration by means of a rigid-soft combination of micropiles and MSE. The accumulated displacement under earthquakes with amplitude of 0.1-0.5g is reduced by 36.3%-46.5%, and the acceleration amplification factor on the top of the wall is reduced by 13.4%, 15.7% and 19.3% based on 0.1, 0.3 and 0.5g input earthquake loading, respectively.In addition, the earthquake-induced failure mode of the MSE wall in steep terrain is the sliding of the MSE region along the backslope, while the micropiles effectively control the sliding trend. The maximum earthquake-induced pile bending moment is in the interface between MSE and slope foundation, so it is necessary to strengthen the reinforcement of the pile body in the interface. Hence, it is proven that the hybrid A-frame micropile/MSE wall system has good seismic performance.  相似文献   

Analysis of dynamic spherical cavity expansion in undrained modified Cam Clay soil     

Hang Zhou  Hanlong Liu  Yingzhen Li 《国际地质力学数值与分析法杂志》2019,43(9):1686-1703

In order to capture the influence of the cavity expansion velocity, this paper presents a semianalytical solution for dynamic spherical cavity expansion in modified Cam Clay (MCC) soil. The key problem is solving the six coupled partial differential equations (PDEs) of cavity expansion, in which the dynamic term is considered in the stress equilibrium equation. The similarity transformation technique is used to transform the PDEs into ordinary differential equations (ODEs). Subsequently, the numerical method using the function “ODE45” in MATLAB is selected to solve the ODEs, which allows the stress and excess pore pressure around the expanding spherical cavity wall to be obtained. The proposed semianalytical solution for dynamic spherical cavity expansion was validated by comparting the degenerate solution with the published quasistatic solution for the MCC model. Parametric study was then conducted to capture the influence of the cavity wall velocity on the cavity expansion response. The proposed solution has potential application to geotechnical problems such as dynamic pile driving, the dynamic cone penetration test, and so forth.  相似文献