横向载荷作用下刚性桩变位规律研究

目前对横向受载刚性桩的研究主要集中在其承载力方面,对变化规律研究很少。为此提出了利用刚性桩上两点位移求桩上任意一点位移、桩回转中心位置及转角的方法。通过对粉质黏土中的刚性桩进行模型试验与数值计算发现,回转中心位置随位移和载荷的增大,先是急剧下降,然后变缓,最后基本趋于稳定,而且桩埋置参数与土力学参数对回转中心位置的变化规律影响很小;而桩的转角随位移增大近似线性变化。比较发现,由试验和数值计算得到的回转中心极限位置与由极限地基反力法得到的结果相差不大     

软土区旋喷式插筋微型桩工艺试验研究

软土地质条件下建筑物的沉降变形和承载力要求越来越高,对基础施工工艺提出了较高要求。在高压旋喷施工工艺的基础上,提出旋喷式插筋微型桩施工工艺,开展了微型桩工艺试验研究,结果表明该工艺大幅提高了单桩桩基承载性能,为实际工程应用提供了技术数据支持。     

粉喷桩加固滨海相软土地基的试验研究

针对连云港地区滨海相软土的工程特性,讨论了采用粉喷桩加固滨海相软土地基的加固效果,包括采用标准贯入试验,取芯无侧限抗压强度值对粉喷桩的桩身质量进行评价以及通过复合地基的静载荷试验评价粉喷桩复合地基,同时根据连云港地区的软土特征建立了标准贯入击数与无侧限抗压强度之间的关系。     

浅议岩溶发育区施工勘察对桩基施工的指导作用

某水泥厂生料均化库桩基工程施工中,通过施工勘察顺利地解决了岩溶发育区冲孔灌注桩施工中持力层选择、全断面入岩判断、溶洞处理及桩基施工顺序等一系列问题.措施行之有效,工程质量良好.     

饱和颗粒正冻土一维刚性冰模型的数值模拟

基于刚性冰模型,应用有限差分法离散方程组,对于饱和颗粒土开放系统的冻结过程进行了一维数值模拟,给出了冻结缘内参数的分布.计算过程中修正了刚性冰模型中分凝冰产生条件,提出以冻结缘内冰压与载荷的关系作为分凝冰产生的判据,计算得到的冻胀量与实验室冻胀实验的测量数据较为吻合.将计算结果与现场实测资料进行了比较,温度场、含水量分布等结果在分布规律方面与现场实测资料相符.     

Three‐dimensional finite element analysis of the interaction between tunneling and pile foundations

This paper concerns analysis of the impact of construction of urban tunnels on adjacent pile foundations. It is carried out using an elastoplastic three‐dimensional finite element modelling. Numerical simulations are performed in two stages, which concern, respectively, the application of the pile axial loading and the construction of the tunnel in presence of the pile foundations. Analysis is carried out for both single piles and groups of piles. Results of numerical simulations show that tunneling induces significant internal forces in adjacent piles. The distribution of internal forces depends mainly on the position of the pile tip regarding the tunnel horizontal axis and the distance of the pile axis from the centre of the tunnel. Analysis of the interaction between tunneling and a group of piles reveals a positive group effect with a high reduction of the internal forces in rear piles. Copyright © 2002 John Wiley & Sons, Ltd.     

既有线重载铁路路桥过渡段路基基床病害及整治措施研究

重载铁路路桥过渡段由于刚性桥台结构物和柔性路堤连接处所产生的刚度差,以及在桥台台尾连接地段因重载列车行车荷载的反复作用,使得静态不平顺、动态不平顺同时存在的条件下,填土在固结沉降过程中易产生较大的差异沉降。这一现象将随着车速的提高和轴重的增大而加剧。因此,对重载铁路过渡段轨下基础的研究具有异常重要的意义。发展重载铁路,路基压实质量的好坏直接影响运输的安全和效能,但长期在\     

刚性桩复合地基水平承载力特性

利用三维非线性弹性有限元方法,研究了刚性桩复合地基在不同垂直荷载作用下的水平承载力特性,分析了不同褥垫层厚度及其地基土的性质对复合地基水平受力特性的影响,得出了水平荷载作用下桩身弯矩和挠度的分布规律。研究表 明,垂直荷载的大小改变了复合地基水平荷载作用下的破坏模式,直接影响着其水平承载力;适当的垫层厚度可降低桩所分担的水平荷载,有利于桩身的安全。     

P–Y Curves for Piles Under Seismic Lateral Loads

This paper describes an experimentally based procedure for building dynamic P–Y curves for clays from the Campeche sound in the Gulf of Mexico and for Mexico City clays. Cyclic triaxial and resonant column tests were used to derive hyperbolic stiffness–strain and damping–strain functions that depend on soil plasticity and on relative consistency. The dynamic P–Y curves incorporate these functions and also include hysteretical and geometrical damping characteristics of the pile–soil system; they can be used directly in dynamic interaction analyses of structure–pile–soil systems in the time or the frequency domains. Usual practice relies on pseudo static formulations and a simplified alternative to include P–Y curves in this kind of analysis is also proposed, which is essentially the same as the dynamic ones but does not include radiation or hysteretical damping.     

A Winkler model approach for vertically and laterally loaded piles in nonhomogeneous soil

An investigation is made to present analytical solutions provided by a Winkler model approach for the analysis of single piles and pile groups subjected to vertical and lateral loads in nonhomogeneous soils. The load transfer parameter of a single pile in nonhomogeneous soils is derived from the displacement influence factor obtained from Mindlin's solution for an elastic continuum analysis, without using the conventional form of the load transfer parameter adopting the maximum radius of the influence of the pile proposed by Randolph and Wroth. The modulus of the subgrade reaction along the pile in nonhomogeneous soils is expressed by using the displacement influence factor related to Mindlin's equation for an elastic continuum analysis to combine the elastic continuum approach with the subgrade reaction approach. The relationship between settlement and vertical load for a single pile in nonhomogeneous soils is obtained by using the recurrence equation for each layer. Using the modulus of the subgrade reaction represented by the displacement influence factor related to Mindlin's solution for the lateral load, the relationship between horizontal displacement, rotation, moment, and shear force for a single pile subjected to lateral loads in nonhomogeneous soils is available in the form of the recurrence equation. The comparison of the results calculated by the present method for single piles and pile groups in nonhomogeneous soils has shown good agreement with those obtained from the more rigorous finite element and boundary element methods. It is found that the present procedure gives a good prediction on the behavior of piles in nonhomogeneous soils. Copyright © 2011 John Wiley & Sons, Ltd.