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Influence of the spatial distribution of soil strength on the bearing capacity of single pile
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摘要: 土体参数可能服从不同类型的分布，而在考虑土性空间变异性的桩基础承载特性的研究中一般将随机变量假定为服从对数正态分布。以土体的不排水强度为随机变量，考虑不同的变异系数和相关距离，采用随机有限元法分别模拟了竖向和水平向荷载作用下单桩基础的承载性状，对比分析了土体不排水强度分别服从对数正态分布、Beta分布和Gamma分布条件下单桩的承载力均值和标准差。结果表明，土体强度的分布形式对单桩竖向承载力的均值没有影响，而服从对数正态分布的随机场中单桩水平承载力均值最大，服从Beta分布的随机场中单桩水平承载力均值最小；竖向荷载和水平荷载作用下Beta分布得到的承载力标准差均为最大。当地基土强度空间分布形式未知时，建议采用Beta分布确定单桩承载力。Abstract: The soil parameters may obey different types of distribution. However, the lognormal distribution is generally chosen in the probability analysis of pile foundations. The undrained strength of soil is taken as the random variable, and it is assumed to obey Lognormal distribution, Beta distribution and Gamma distribution, respectively. Then the bearing behavior of single pile foundation under vertical and horizontal loads is simulated by stochastic finite element method, in which the different coefficient of variation and correlation distance are considered. The mean value and standard deviation of bearing capacity of single pile are analyzed. The results show that the average vertical bearing capacity of single pile is not affected by the distribution of soil strength. The average horizontal bearing capacity of single pile is the largest when the lognormal distribution is adopted, while the bearing capacity is the smallest when random field obeys the Beta distribution. The standard deviation of bearing capacity obtained by Beta distribution under vertical and horizontal loads is the largest. It is recommended to use Beta distribution to determine the bearing capacity of single pile foundation when the spatial distribution of soil strength is unknown.
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Key words:
- spatial variability /
- pile foundation /
- non-Gaussian random field /
- undrained strength
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图 3 Beta分布下变异系数对竖向承载力均值及标准差的影响
Figure 3. Influence of variation coefficient on mean value of vertical bearing capacity and standard deviation under Beta distribution
图 4 Beta分布下变异系数对水平承载力均值及标准差的影响
Figure 4. Influence of variation coefficient on mean value of horizontal bearing capacity and standard deviation under Beta distribution
图 5 分布形式对竖向承载力均值及标准差的影响
Figure 5. Influence of distribution form on mean value of vertical bearing capacity and standard deviation
图 6 分布形式对水平承载力均值和标准差的影响
Figure 6. Influence of distribution on mean value of horizontal bearing capacity and standard deviation
表 1 3种分布的PDF函数
Table 1. Three standard non-Gaussian distributions
分布 概率密度函数（PDF） 对数正态 $f(x,\mu ,\sigma ) = \dfrac{1}{ {\sqrt {2{\rm{ {\text{π} } } } } \sigma x} }\exp \left[ { - \dfrac{1}{ {2{\sigma ^2} } }{ {(\ln x - \mu )}^2} } \right]$ Beta $f(x,\alpha ,\beta ) = \dfrac{ {\varGamma (\alpha + \beta )} }{ {\varGamma (\alpha )\Gamma (\beta )} }{x^{\alpha - 1} }{(1 - x)^{\beta - 1} }$ Gamma $f(x,\alpha ,\beta ) = \dfrac{ { {\alpha ^\beta } } }{ {\varGamma (\alpha )} }{x^{\beta - 1} }{{\rm{exp}}({ - \alpha x}) }$ 
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表 2 工况设置与编号
Table 2. Test programs and numbers
变异系数 工况编号 0.1、0.3、0.5 X8Y4 X8Y8 X16Y8 X32Y4 X8Y4 X8Y8 X16Y8 X32Y4 X8Y4 X8Y8 X16Y8 X32Y4
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[1] GRIFFITHS D V, FENTON G A. Seepage beneath water retaining structures founded on spatially random soil[J]. Géotechnique, 1993, 43(4): 577-587. [2] GRIFFITHS D V, FENTON G A. Probabilistic slope stability analysis by finite elements[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2004, 130(5): 507-518. doi: 10.1061/(ASCE)1090-0241(2004)130:5(507) [3] LI D Q, JIANG S H, CAO Z J, et al. A multiple response-surface method for slope reliability analysis considering spatial variability of soil properties[J]. Engineering Geology, 2015, 187: 60-72. doi: 10.1016/j.enggeo.2014.12.003 [4] LIU L L, DENG Z P, ZHANG S H, et al. Simplified framework for system reliability analysis of slopes in spatially variable soils[J]. Engineering Geology, 2018, 239: 330-343. doi: 10.1016/j.enggeo.2018.04.009 [5] GRIFFITHS D V, FENTON G A, MANOHARAN N. Bearing capacity of rough rigid strip footing on cohesive soil: probabilistic study[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2002, 128(9): 743-755. doi: 10.1061/(ASCE)1090-0241(2002)128:9(743) [6] FENTON G A, GRIFFITHS D V. Three-dimensional probabilistic foundation settlement[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2005, 131(2): 232-239. doi: 10.1061/(ASCE)1090-0241(2005)131:2(232) [7] CHO S E, PARK H C. Effect of spatial variability of cross-correlated soil properties on bearing capacity of strip footing[J]. International Journal for Numerical and Analytical Methods in Geomechanics, 2010, 34(1): 1-26. doi: 10.1002/nag.791 [8] PUŁA W, RÓŻAŃSKI A. Reliability of rigid piles subjected to lateral loads[J]. Archives of Civil and Mechanical Engineering, 2012, 12(2): 205-218. doi: 10.1016/j.acme.2012.04.007 [9] TEIXEIRA A, HONJO Y, GOMES CORREIA A, et al. Sensitivity analysis of vertically loaded pile reliability[J]. Soils and Foundations, 2012, 52(6): 1118-1129. doi: 10.1016/j.sandf.2012.11.025 [10] 杨剑, 黎冰, 鲍安琪, 等. 考虑土性参数空间变异性的单桩竖向承载力分析[J]. 水利水运工程学报,2019(5):85-90. (YANG Jian, LI Bing, BAO Anqi, et al. Analysis of vertical bearing capacity of single pile foundations considering spatial variability of soil parameters[J]. Hydro-Science and Engineering, 2019(5): 85-90. (in Chinese) doi: 10.12170/201905011 [11] 韩吉伟, 刘晓明, 杨月红, 等. 考虑土体强度空间变异性的单桩水平承载力研究[J]. 水利水运工程学报,2020(6):108-114. (HAN Jiwei, LIU Xiaoming, YANG Yuehong, et al. Study on the horizontal bearing capacity of single pile foundation considering spatial variability of soil strength[J]. Hydro-Science and Engineering, 2020(6): 108-114. (in Chinese) [12] JAMSHIDI CHENARI R, GHORBANI A, ESLAMI A, et al. Behavior of piled raft foundation on heterogeneous clay deposits using random field theory[J]. Civil Engineering Infrastructures Journal, 2018, 51(1): 35-54. [13] HALDAR S, BABU G L S. Effect of soil spatial variability on the response of laterally loaded pile in undrained clay[J]. Computers and Geotechnics, 2008, 35(4): 537-547. doi: 10.1016/j.compgeo.2007.10.004 [14] POPESCU R, DEODATIS G, NOBAHAR A. Effects of random heterogeneity of soil properties on bearing capacity[J]. Probabilistic Engineering Mechanics, 2005, 20(4): 324-341. doi: 10.1016/j.probengmech.2005.06.003 [15] CAO Z J, WANG Y. Bayesian model comparison and characterization of undrained shear strength[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2014, 140(6): 04014018. doi: 10.1061/(ASCE)GT.1943-5606.0001108 [16] WANG Y, ZHAO T Y, CAO Z J. Site-specific probability distribution of geotechnical properties[J]. Computers and Geotechnics, 2015, 70: 159-168. doi: 10.1016/j.compgeo.2015.08.002 [17] WU Y X, ZHOU X H, GAO Y F, et al. Effect of soil variability on bearing capacity accounting for non-stationary characteristics of undrained shear strength[J]. Computers and Geotechnics, 2019, 110: 199-210. doi: 10.1016/j.compgeo.2019.02.003 [18] WU Y X, GAO Y F, ZHANG L M, et al. How distribution characteristics of a soil property affect probabilistic foundation settlement: from the aspect of the first four statistical moments[J]. Canadian Geotechnical Journal, 2020, 57(4): 595-607. doi: 10.1139/cgj-2019-0089 [19] ZHOU W, HONG H P, SHANG J Q. Probabilistic design method of prefabricated vertical drains for soil improvement[J]. Journal of Geotechnical and Geoenvironmental Engineering, 1999, 125(8): 659-664. doi: 10.1061/(ASCE)1090-0241(1999)125:8(659) -
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