1、 1 中文 6170 字 出处： Yang M, Zhang X, Zhao M. A simplified approach for settlement calculation of pile groups considering pile-to-pile interaction in layered soilsJ. Journal of Central South University of Technology, 2011, 18: 2131-2136. 附录 1 A simplified approach for settlement calculation of pile grou
2、ps considering pile-to-pile interaction in layered soils 1 Introduction Piles, generally arranged in groups, are used in various applications to support structures exposed to vertical loads. In many cases, the settlement of pile groups is the controlling factor in design because the primary purpose
3、of pile groups is to limit the deformation of structures. Therefore, many researchers have proposed different methods to investigate the behavior of the settlement of pile groups. The current methods for estimating the settlement of pile groups can be categorized as: 1) Numerical methods, such as fi
4、nite element method, and boundary element method. As a very powerful technique, numerical methods can readily calculate the settlements of pile groups in terms of the nonlinearity of soils and the interaction between individual piles by performing full three-dimensional-models for pile groups. Howev
5、er, the application of numerical methods is limited in practice for the complex modeling procedures and the high computational requirements, especially for large numbers of pile groups. 2) Equivalent pier methods. The methods consider the pile groups as a whole pier to simplify the procedure for est
6、imating the settlement of pile groups which equals that of single pile by means of load-transfer function. The obvious drawback of equivalent pier method is that the computed settlement is only relative to the size of the equivalent pier by neglecting the influence of the pile number and pile space
7、in pile groups. 3) Superimposing methods. The methods, originally introduced by POULOS, are widely used recently which estimate the settlements of pile groups by superimposing the interaction factors of any two individual piles. LEE developed a procedure to calculate the interaction factors for both
8、 rigid and flexible pile groups. COSTANZO and LANCELLOTA proposed an approximate solution to evaluate the interaction factors taking into account the nonlinearity characteristic of surrounding soil around piles. WONG 2 and POULOS modified the interaction factors which can account for the different t
9、ype of piles. However, the superimposing method does not consider the reinforcing effects of pile group, i.e. the settlement reduction of soils due to the presence of the neighboring piles. As a result, the computed settlement of pile groups is usually greater than the actual result. Therefore, it i
10、s required that developing a simplified approach for estimating the settlement of pile groups considering the reinforcing effect of piles induced by the interaction between individual piles in pile groups which can readily be used in practice. This work presents a simplified approach to carry out a
11、load settlement analysis of pile groups subjected to vertical loads in layered soils by using two models. First, the shear-deformation model of soils deduced from the method presented by RANDOLPH and WROTH, is developed to simulate the interaction between individual piles in pile groups. The load-tr
12、ansfer model, general used in analyzing the behaviors of single piles, is then extended to estimate the settlement of pile groups by accounting for the interaction between individual piles. Consequently, the relationship between the settlement and the vertical load of pile groups is developed. Resul
13、ts of a certain laboratory on pile groups are used to verify the proposed approach in this work. The influences of the pile space and pile length on the settlement of pile groups are also discussed. 2 Interaction between piles This work focuses on the vertically-loaded pile groups consisting of n id
14、entical piles with the same length L, diameter d, pile space S, and elastic modulus Epembedded in layered soils, as shown in Fig.1(a).Generally, the resistance of the surrounding soils at thepile/soil interface, i.e. shaft frictional force named as z , is mobilized once the displacement of the piles
15、 occurs. The displacement of pile groups at a given depth is different from that of single pile under the same load due to the fact that the reinforcing effect caused by the interaction between some neighboring piles confines the displacement of soils along piles. Therefore, it is necessary to consi
16、der the interaction between individual piles in calculating the settlement of pile groups. The soils are assumed to be a series of nonlinear springs attached along the pile shaft to simulate the behaviors of soils subjected to shaft frictional force, as shown in Fig.1(b). Obviously, the stiffness of
17、 springs, denoted as the ratio of the shaft 3 frictional force to the displacement of soils, is relative to the interaction between individualpiles in pile group. Fig.1 Sketch of pile groups located in layered soils Considered the interaction between any two piles with the pile space Sij in pile gro
18、up, i and j, as shown in Fig.2. For pile i, the vertical displacement of the surrounding soil at depth z, defined as wi(z), is composed of three parts: the first, named as wii(z), is caused by the shaft frictional force of pile i itself at depth z； the second is due to the shaft frictional force of
19、pile j at the same depth z, wij(z)； the third is the reduction part induced by the reinforce-effect of pile j, wij (z).Likewise, the values of the equivalent stiffness of springs are also composed of the same three parts. The procedure of calculating each part of the soil vertical displacement and the equivalent stiffness of springs are presented as follows.
