考虑注浆压力影响锚–土界面剪切蠕变Kriging模型
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摘要
锚–土界面剪切蠕变特性直接关系到锚杆支护系统的长期锚固性能,而工程锚杆施工中通常采用的压力注浆对锚固体–土体界面蠕变特性有重要影响。为研究不同注浆压力下的锚–土界面剪切蠕变特性,本文利用自主研制的压力注浆装置制作了不同注浆压力下的锚杆微元体试样,利用自行设计制作的锚–土界面剪切蠕变特性测试系统对试样进行分级加载,获得了不同注浆压力下的锚-土界面剪切蠕变全过程曲线,利用"陈氏加载法"将蠕变全过程曲线转化为分别加载蠕变曲线,并采用等时曲线法获得不同注浆压力下的锚–土界面长期抗剪强度。为提高建模精度,提出了将蠕变试验曲线经对数转换后来建立蠕变模型的方法,并引入Kriging法,建立了考虑注浆压力影响的锚–土界面剪切蠕变Kriging模型。通过所建模型的预测结果与试验结果对比分析发现,本文方法建立的锚–土界面剪切蠕变模型,其拟合和预测精度均很高。
The long-term work performance of anchored systems depends on the shear creep behavior of anchor-soil interface.The technology of pressure grouting used in the construction of anchored systems is recognized to influence the creep behavior of anchor-soil interface greatly. A specially apparatus with capability of applying different grouting pressures is designed to investigate the impact of grouting pressures for the anchor-soil interface. The element-anchor specimens with different grouting pressures are made by using this apparatus. The time-history curves of pullout displacement are obtained in applying multi-stage loading to those prepared specimens by a specially designed creep pullout device. Chen's method is adopted to transform those individual time-history curves of pullout displacement into a group of creep curves with varying loading stresses for each anchor specimen equivalently. Using the isochronal curve method the long-term shear strengths of anchor-soil interface are derived for the specimens with different grouting pressures. Aiming to improve the modelling precision, the creep curves with natural time coordinate are rebuilt to logarithmic time coordinates. The Kriging creep model for anchor-soil interface accounting for grouting pressure is established based on the Kriging method. Comparison between the predicted and the measured results for creep response validates that the proposed creep model has high precision in the fitting and prediction.
The long-term work performance of anchored systems depends on the shear creep behavior of anchor-soil interface.The technology of pressure grouting used in the construction of anchored systems is recognized to influence the creep behavior of anchor-soil interface greatly. A specially apparatus with capability of applying different grouting pressures is designed to investigate the impact of grouting pressures for the anchor-soil interface. The element-anchor specimens with different grouting pressures are made by using this apparatus. The time-history curves of pullout displacement are obtained in applying multi-stage loading to those prepared specimens by a specially designed creep pullout device. Chen's method is adopted to transform those individual time-history curves of pullout displacement into a group of creep curves with varying loading stresses for each anchor specimen equivalently. Using the isochronal curve method the long-term shear strengths of anchor-soil interface are derived for the specimens with different grouting pressures. Aiming to improve the modelling precision, the creep curves with natural time coordinate are rebuilt to logarithmic time coordinates. The Kriging creep model for anchor-soil interface accounting for grouting pressure is established based on the Kriging method. Comparison between the predicted and the measured results for creep response validates that the proposed creep model has high precision in the fitting and prediction.
引文
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[4]高傑.红黏土土层锚杆蠕变特性试验及理论研究[D].长沙:湖南大学,2018.(GAO Jie.Study of creep characteristic and theory for grouted anchor in red clay[D].Changsha:Hunan University,2018.(in Chinese))
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[8]TAMARA A B,SOUBRA A H,JAWAD T.Kriging-based reliability analysis of strip footings resting on spatially varying soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2018,144(10):04018071.
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[2]陈昌富,刘俊斌,徐优林,等.锚-土界面剪切蠕变试验及其经验模型研究[J].岩土工程学报,2016,38(10):1762-1768.(CHEN Chang-fu,LIU Jun-bin,XU You-lin,et al.Tests on shearing creep of anchor-soil interface and its empirical model[J].Chinese Journal of Geotechnical Engineering,2016,38(10):1762-1768.(in Chinese))
[3]高傑,朱世民,陈昌富.基于RBF神经网络的红黏土-锚固体界面蠕变模型[J].岩土工程学报,2018,40(增刊2):122-126.(GAO Jie,ZHU Shi-min,CHEN Chang-fu.RBFneural net-work based creep model of red clay-anchor interface[J].Chinese Journal of Geotechnical Engineering,2018,40(S2):122-126.(in Chinese))
[4]高傑.红黏土土层锚杆蠕变特性试验及理论研究[D].长沙:湖南大学,2018.(GAO Jie.Study of creep characteristic and theory for grouted anchor in red clay[D].Changsha:Hunan University,2018.(in Chinese))
[5]YIN J H,ZHOU W H.Influence of grouting pressure and overburden stress on the interface resistance of a soil nail[J].Journal of Geotechnical and Geoenvironmental Engineering,2009,135(9):1198-1209.
[6]KRIGE D G.A statistical approach to some basic mine valuation problems on the Witwatersrand[J].Journal of the Southern African Institute of Mining and Metallurgy,1951,52(6):119-139.
[7]ZHANG J,HUANG H W,PHOON K K.Application of the kriging-based response surface method to the system reliability of soil slopes[J].Journal of Geotechnical and Geoenvironmental Engineering,2013,139(4):651-655.
[8]TAMARA A B,SOUBRA A H,JAWAD T.Kriging-based reliability analysis of strip footings resting on spatially varying soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2018,144(10):04018071.
[9]TAN T K,KANG W F.Locked in stresses,creep and dilatancy of rocks,and constitutive equations[J].Rock Mechanics,1980,13(1):5-22.
[10]CHUNG H S,ALONSO J J.Using gradients to construct cokriging approximation models for high-dimensional de-sign optimization problems[R].AIAA 2002-0317,2002.