A multidirectional semi‐analytical method for analysis of laterally loaded pile groups in multi‐layered elastic strata          下载免费PDF全文

F.S. Tehrani  M. Prezzi  R. Salgado 《国际地质力学数值与分析法杂志》2016,40(12):1730-1757

A semi‐analytical method for calculating the response of single piles and pile groups subjected to lateral loading is developed in this paper. Displacements anywhere in the soil domain are tied to the displacements of the piles through decay functions. The principle of virtual work and the calculus of variations are used to derive the governing differential equations that describe the response of the piles and soil. The eigenvalue method and the finite difference technique are used to solve the system of coupled differential equations for the piles and soil, respectively. The proposed method takes into account the soil surface displacement along and perpendicular to the loading direction and produces displacement fields that are very close to those produced by the finite element method but at lower computational effort. Compared with the previous method that considered only the soil displacement along the loading direction, accounting for the multi‐directional soil displacement field produces responses for the piles and soil that are closer to those approximated by the finite element method. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Development of the cyclic p–y curve for a single pile in sandy soil     

Sung-Ha Baek  Joonyoung Kim  Seung-Hwan Lee 《Marine Georesources & Geotechnology》2018,36(3):351-359

Pile foundations that support transmission towers or offshore structures are dominantly subjected to cyclic lateral load induced by wind and waves. For a successful design, it is crucial to investigate the effect of cyclic lateral loads on the pile behavior that is loaded laterally. Although the p–y curve method is generally utilized to design the cyclic laterally loaded pile foundations, the effect of cyclic lateral loads on the pile has not been properly implemented with the p–y curve. This reflects a lack of consideration of the overall stiffness change in soil–pile interaction. To address this, a series of model pile tests were conducted in this study on a preinstalled aluminum flexible pile under various sandy soil conditions. The test results were used to investigate the effect of cyclic lateral loads on the p–y behavior. The cyclic p–y curve, which properly takes into account this effect, was developed as a hyperbolic function. Pseudo-static analysis was also conducted with the proposed cyclic p–y curve, which showed that it was able to properly simulate cyclic laterally loaded pile behavior in sandy soil.  相似文献   

Dissolved inorganic carbon evolution in neutral discharge from mine tailings piles          下载免费PDF全文

Hendratta N. Ali  Eliot A. Atekwana 《水文研究》2016,30(13):2079-2091

We measured the concentrations of dissolved inorganic carbon (DIC) and major ions and the stable carbon isotope ratios of DIC (δ¹³C_DIC) in two creeks discharging from carbonate‐rich sulphide‐containing mine tailings piles. Our aim was to assess downstream carbon evolution of the tailings discharge as it interacted with the atmosphere. The discharge had pH of 6.5–8.1 and was saturated with respect to carbonates. Over the reach of one creek, the DIC concentrations decreased by 1.1 mmol C/l and δ¹³C_DIC increased by ~4.0‰ 200 m from the seep source. The decrease in the DIC concentrations was concomitant with decreases in the partial pressure of CO_2(aq) because of the loss of excess CO_2(aq) from the discharge. The corresponding enrichment in the δ¹³C_DIC is because of kinetic isotope fractionation accompanying the loss of CO_2(g). Over the reach of the other creek, there was no significant decrease in the DIC concentrations or notable changes in the δ¹³C_DIC. The insignificant change in the DIC concentrations and the δ¹³C_DIC is because the first water sample was collected 160 m away from the discharge seep, not accessible during this research. In this case, most of the excess CO_2(aq) was lost before our first sampling station. Our results indicate that neutral discharges from tailings piles quickly lose excess CO_2(aq) to the atmosphere and the DIC becomes enrich in ¹³C. We suggest that a significant amount of carbon cycling in neutral discharges from tailings piles occur close to the locations where the discharge seeps to the surface. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Analysis of rectangular piles subjected to lateral loads in nonhomogeneous soil using a Winkler model approach          下载免费PDF全文

Hiroyoshi Hirai 《国际地质力学数值与分析法杂志》2015,39(9):937-968

An analytical approach using a Winkler model based on two lateral soil displacement components in a three‐dimensional soil is investigated to provide analytical solutions of horizontal response of a rectangular pile subjected to lateral loads in nonhomogeneous soil. The two lateral displacement components of a soil surrounding the rectangular pile are represented by the Fourier series of displacement potential functions in the elastic three‐dimensional analysis. The lateral stiffness coefficient of the rectangular pile shaft in nonhomogeneous soil is derived from the rocking stiffness coefficient taking into account rocking rotation of a rigid pile shaft. The relationship between horizontal displacement, rotation, moment, and shear force for the rectangular pile subjected to horizontal loads in nonhomogeneous soil is obtainable in the form of the recurrence equation. The formulation of lateral displacement and rotation for a rectangular pile subjected to lateral loads on the pile base in nonhomogeneous soil is proposed by taking into account Mindlin's equation and the equivalent thickness for soil layers in the equivalent elastic method. The difference of lateral behavior between square and circular piles subjected to lateral loads is insignificant. The effect of aspect ratio of the rectangular pile on the lateral behavior is great for the lower stiffness ratio between pile and soil and the larger length–equivalent diameter ratio. The effect of the value of Poisson's ratio of soil on lateral stiffness coefficient is relatively small except Poisson's ratio close to 0.5. The comparison of the results calculated by the current method for a rectangular pile subjected to lateral loads in nonhomogeneous soil has shown good agreement with those obtained from the analytical methods and the finite element method. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Experimental investigation on seismic behavior of single piles in sandy soil     

Werasak Raongjant 《地震工程与工程振动(英文版)》2011,10(3):417-422

This paper describes a quasi-static test program featuring lateral cyclic loading on single piles in sandy soil. The tests were conducted on 18 aluminum model piles with different cross sections and lateral load eccentricity ratios, e/d, (e is the lateral load eccentricity and d is the diameter of pile) of 0, 4 and 8, embedded in sand with a relative density of 30% and 70%. The experimental results include lateral load-displacement hysteresis loops, skeleton curves and energy dissipation curves. Lateral capacity, ductility and energy dissipation capacity of single piles under seismic load were evaluated in detail. The lateral capacities and the energy dissipation capacity of piles in dense sand were much higher than in loose sand. When embedded in loose sand, the maximum lateral load and the maximum lateral displacement of piles increased as e/d increased. On the contrary, when embedded in dense sand, the maximum lateral load of piles decreased as e/d increased. Piles with a higher load eccentricity ratio experienced higher energy dissipation capacity than piles with e/d of 0 in both dense and loose sand. At a given level of displacement, piles with circular cross sections provided the best energy dissipation capacity in both loose and dense sand.  相似文献   

Numerical simulations and parametric study of SDCM and DCM piles under full scale axial and lateral loads     

Panich Voottipruex  Taweephong Suksawat  D.T. Bergado  Pitthaya Jamsawang 《Computers and Geotechnics》2011

The new kind of reinforced Deep Cement Mixing (DCM) pile namely, Stiffened Deep Cement Mixing (SDCM) pile is introduced to mitigate the problems due to the low flexural resistance, quality control problem and unexpected failure of DCM pile. The SDCM pile consists of DCM pile reinforced with concrete core pile. Previously, the full scale pile load test and the full scale embankment loading test were successfully conducted in the field. To continue the study on the behavior of SDCM and DCM piles, the 3D finite element simulations using PLAXIS 3D Foundation Software were conducted in this study. The simulations of full scale pile load test consisted of two categories of testing which are the axial compression and the lateral loading. For DCM C-1 and C-2 piles, the clay–cement cohesion, C_DCM, and clay–cement modulus, E_DCM, were obtained from simulations as 300 kPa and 200 kPa as well as 60,000 kPa and 40,000 kPa, respectively. For the SDCM piles, the simulation results show that increasing length ratio, L_core/L_DCM, increased the bearing capacity whereas the sectional area ratio, A_core/A_DCM, has only small effects on the bearing capacity for the axial compression loading. The verified parameters such as the clay–cement cohesion, C_DCM, and clay–cement modulus, E_DCM, from simulations of axial compression tests were 200 kPa and 30,000 kPa, respectively. On the other hand, increasing the sectional area ratio, A_core/A_DCM, significantly influenced the ultimate lateral resistance while the length ratio, L_core/L_DCM, is not significant in the ultimate lateral load capacity when the length of concrete core pile is longer than 3.5 m. In addition, the tensile strength of DCM, T_DCM, and concrete core pile, T_core, are very important to the lateral pile resistance. The back-calculation results from simulations of tensile strength were 5000 kPa and 50 kPa for the T_core and T_DCM, respectively.  相似文献   

苏通大桥超长桩桩底后压浆试验及效果          下载免费PDF全文

彭仕奇 《探矿工程》2011,38(11):54-58

在苏通大桥松散软弱的地层条件,实施超长（〉100 m）、超大（2.5 m）摩擦桩桩底后压浆工程,在我国是首次运用。结合工程实践,就压浆工程的设计、施工的技术要点进行全面介绍。通过对钻孔取样分析,指出浆液初凝时间地表实验与地下实际存在较大差异;通过施工体验,结合取样显示的浆液扩散渗透状况,提出可渗透地层以注浆量为控制参数,压力不列为控制参数的思路。  相似文献   

提高钻孔桩桩底压浆工效及保证质量的技术措施          下载免费PDF全文

刘宝新  唐世杰  陈跃武 《探矿工程》2011,38(10):56-59

钻孔桩桩底压浆技术是向钻孔灌注桩桩底沉渣和围岩土体内压入一定量水泥浆,使桩底沉渣和桩底一定范围土体孔隙内充满水泥浆液,经物理、化学作用使其强度大幅提高,从而实现单桩竖向承载力的提高。结合高铁钻孔桩桩底压浆施工实践,介绍了2种压浆工艺过程,阐明了提高压浆工效、保证注浆质量关键技术措施实施的重要性。  相似文献   

旋挖钻机与冲击钻机组合在嵌岩桩施工中的应用          下载免费PDF全文

孙琦  仲文涛  李玉成 《探矿工程》2011,38(8):50-52

旋挖钻机施工工艺和正循环冲击钻机施工工艺相结合,充分发挥了旋挖钻机施工土层速度快和正循环冲击钻机施工岩层速度快的优点,从而打破嵌岩桩施工的传统工艺,为大口径嵌岩桩施工提供经验和技术参考。通过镇江市体育会展中心体育场桩基工程采用旋挖钻机施工工艺和正循环冲击钻机组合成孔工艺的成功实例,介绍了该工艺的施工技术措施及注意要点。  相似文献   

娄江特大桥深孔泵吸反循环工艺的改进          下载免费PDF全文

张广亮  刘建涛  陈益敏 《探矿工程》2011,38(6):47-50

随着国家基础设施投入的加大,桩径1000－2000 mm、孔深100－130 m的钻孔灌注桩在各类工程中屡被采用。泵吸反循环传统上被用于孔深不超过80 m的深孔,在京沪高铁第六标段娄江特大桥钻孔灌注桩施工中,通过对现有的反循环钻机进行改进,很大程度上提高了泵吸反循环的工作效率,顺利地完成了孔深131 m、桩径1.8 m桩孔的施工,产生了很好的经济效益。  相似文献