大型槽仓基坑填方加筋土筋带变形实测分析
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摘要
针对目前土工筋带测试存在可靠性低和成本高昂的困境,自行研制了基于复合导电材料的新型筋带大变形传感元件,并成功应用于内蒙某大型槽仓基坑填方加筋带变形监测项目中。结果表明:土工筋带变形随上覆填土厚度增加呈阶梯状增大,其中相邻上层填土对筋带受力影响最大,至上覆填土2～3层后变形逐渐趋于稳定,即各层筋带施工危险期为该层以上填土施工前期。沿筋带长度方向上,各测点变形出现不均匀性和随填土高度增加动态调整的过程,但所有测点变形最大不超过1.8%,且部分测点出现受挤压现象。相应地填方底部的竖向土压力测值也随填土厚度增加呈线性增大,最大达250 kPa,且同一纵线方向上不同测点土压也呈现出不均匀性和多峰性。而墙背土压则基本也只受其上2～3层填土影响,其后趋于稳定且总值不大。最后,对填方加筋土的潜在破裂面形式分析为指数函数的直曲滑面,并结合不同高度处筋带变形最大值分布规律提出了现场铺设密度优化的建议。
In allusion to low reliability and high cost in the test of geotechnical reinforcement ribbon at present,a new type of large deformation sensing element is developed based on composite conductive material and is successfully applied to deformation monitoring project in a large foundation pit of coal bunker in Inner Mongolia. The result shows that the increase of deformation in geotechnical reinforcement ribbon is ladder-like with the overlying filling thickness increasing. Geotechnical reinforcement ribbon is impacted seriously by adjacent upper filled soil. Deformation gradually becomes stable after 2 ～ 3 layers overlying soil. Namely the construction crisis of each layer geotechnical reinforcement ribbon happens in the above fill prophase construction. Each measuring point deformation is inhomogeneity and the process of dynamic adjusts with filling height increasing along the length of ribbon direction.But all the point 's biggest deformation does not exceed 1. 8% and some stations are affected by extrusion.Accordingly,seepage at the bottom of the vertical earth pressure measurements also increases with filling thickness increasing linearly. The largest is 250 KPa. Different soil pressure measuring point in the same ordinate direction also presents the inhomogeneity and multimodal. While the wall back earth pressure basic is 2 ～ 3 layer filling effect and tend to be more stable and less gross. Finally,the potential failure surface of sliding surface is analyzed and the form of sliding surface is index function. Suggestions of laying density optimization are put forward combined with different heights in ribbon maximum deformation distribution site.
In allusion to low reliability and high cost in the test of geotechnical reinforcement ribbon at present,a new type of large deformation sensing element is developed based on composite conductive material and is successfully applied to deformation monitoring project in a large foundation pit of coal bunker in Inner Mongolia. The result shows that the increase of deformation in geotechnical reinforcement ribbon is ladder-like with the overlying filling thickness increasing. Geotechnical reinforcement ribbon is impacted seriously by adjacent upper filled soil. Deformation gradually becomes stable after 2 ～ 3 layers overlying soil. Namely the construction crisis of each layer geotechnical reinforcement ribbon happens in the above fill prophase construction. Each measuring point deformation is inhomogeneity and the process of dynamic adjusts with filling height increasing along the length of ribbon direction.But all the point 's biggest deformation does not exceed 1. 8% and some stations are affected by extrusion.Accordingly,seepage at the bottom of the vertical earth pressure measurements also increases with filling thickness increasing linearly. The largest is 250 KPa. Different soil pressure measuring point in the same ordinate direction also presents the inhomogeneity and multimodal. While the wall back earth pressure basic is 2 ～ 3 layer filling effect and tend to be more stable and less gross. Finally,the potential failure surface of sliding surface is analyzed and the form of sliding surface is index function. Suggestions of laying density optimization are put forward combined with different heights in ribbon maximum deformation distribution site.
引文
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[3]魏丽敏,张军乐,何群.差异沉降对加筋土挡墙筋带内力与变形的影响[J].中国铁道科学,2004,25(5):89-93.
[4]闫澍旺,王翠,于志强.加筋垫层土工织物中应力现场测试分析[J].岩土力学,2007,28(增1):873-876.
[5]杨广庆,蔡英.高路堤加筋土档土墙的变形和受力研究[J].岩石力学与工程学报,2003,22(2):321-326.
[6]王祥,周顺华,顾湘生,等.路堤式加筋土挡墙的试验研究[J].土木工程学报,2005,38(10):119-124.
[7]王维,黄向京.加筋格宾结构分析理论与工程应用新技术[M].北京:人民交通出版社,2011.
[8]刘泽,杨果林,黄向京.倾斜面墙加筋挡墙施工过程仿真与潜在破裂面分析[J].工程勘察,2011,39(10):1-7.
[9]叶观宝,张振,邢皓枫,等.面板对路堤式加筋土挡墙力学特性的影响[J].岩土力学,2012,33(3):881-886.
[10]Yang G,Zhang B,Lv P,et al.Behaviour of geogrid reinforced soil retaining wall with concrete-rigid facing[J].Geotextiles&Geomembranes,2009,27(5):350-356.
[11]Won M S,Kim Y S.Internal deformation behavior of geosynthetic-reinforced soil walls[J].Geotextiles&Geomembranes,2007,25(1):10-22.
[12]Abdullah C H,Edil T B.Behaviour of geogridreinforced load transfer platforms for embankment on rammed aggregate piers[J].Geosynthetics International,2007,14(3):141-153.
[13]Hayden S A,Humphrey D N,Christopher B R,et al.Effectiveness of geosynthetics for roadway construction in cold regions:results of a multi-use test section[A]∥Geosynthetics’99:Specifying Geosynthetics and Developing Design Details[C].1999:847-862.
[14]廖波,周国庆,梁恒昌,等.胶基电敏传感元件大变形拉伸试验研究[J].煤炭学报,2011,36(11):1832-1835.
[15]廖波.炭黑/硅橡胶导电敏感复合材料可重复性试验研究[J].传感技术学报,2014(9):1164-1168.
[16]廖波,常传源,季雨坤,等.土工筋带变形测试传感器研发与试验研究[J].传感技术学报,2016,29(12):1931-1935.
[17]中华人民共和国国家标准编写组.土工合成材料应用技术规范(GB/T50290-2014)[S].北京:中国计划出版社,2014.