PDF(6723 KB)
Experimental Study on Friction Characteristics of Geogrid-Loess Interface
CAI Xiao-guang, YUAN Chao, LI Si-han, XU Hong-lu, WANG Xue-peng
Journal of Changjiang River Scientific Research Institute ›› 2025, Vol. 42 ›› Issue (8) : 111-117.
PDF(6723 KB)
PDF(6723 KB)
Experimental Study on Friction Characteristics of Geogrid-Loess Interface
[Objective] Geogrids are widely applied in high loess slopes engineering due to their advantages of strong overall durability, high tensile strength, and corrosion resistance. The interface friction coefficient between the reinforcement and soil is a crucial parameter for pull-out verification of reinforced soil slopes, and its value is influenced by multiple factors. [Method] This study employed an independently developed geosynthetic material tensile pull-out testing system to conduct a series of laboratory pull-out tests on steel-plastic geogrids and remolded loess under varying normal stresses, pull-out rates, and water contents, aiming to investigate the effects of these factors on the friction characteristics of the steel-plastic geogrid-loess interface. [Results] The peak pull-out force of the reinforcement increased with increasing normal stress and decreased with increasing water content, with a maximum value of 18.143 kN. Under different normal stresses, the relationship between pull-out force and displacement at the loading end was divided into four stages,such as linear increase, nonlinear increase, decay, and stabilization. The pull-out force increased with the pull-out rate, and higher pull-out rates corresponded to greater peak pull-out forces. Although the pull-out rate varied, the trend of the pull-out force versus loading end displacement curve remained similar; as the loading end displacement continuously increased, the pull-out force first increased, then decreased, and finally tended to stabilize. The maximum shear stress increased with normal stress and decreased with water content; the influence of normal stress on maximum shear stress weakened gradually as water content increased. The interface cohesion showed a trend of first increasing and then decreasing with rising water content, reaching a maximum of 11.043 kPa at the optimal water content. The apparent friction coefficient decreased with increasing water content and normal stress; when the normal stress was 105 kPa, the apparent friction coefficient was approximately 0.13, which was about one-third to one-half of the recommended standard value. [Conclusion] The pull-out characteristic tests indicate that engineering design should not be evaluated solely based on the apparent friction coefficient, but should also fully consider actual water content, overburden load, and other engineering conditions. The results of this study provide a reference for the structural design of high loess slopes.
geogrid / pull-out test / normal stress / interface characteristic / apparent friction coefficient
| [1] |
李波, 徐丽珊, 龚壁卫, 等. 加筋高陡边坡离心模型试验与数值模拟[J]. 长江科学院院报, 2014, 31(3):65-68,76.
采用离心模型试验和二维有限元法, 研究加筋高陡边坡的加筋机理及其对边坡稳定性的影响。开展2组离心模型试验, 逐级增大加速度直至边坡发生破坏, 分析无加筋边坡与加筋边坡的变形和土压力随分级加载过程的变化规律。基于离心模型试验的基本参数, 建立有限元模型, 通过对比计算结果与离心模型试验结果, 验证数值模型的合理性;进一步采用该数值模型开展填料强度与加筋体抗拉强度对边坡稳定性的敏感性分析。研究结果表明:加筋体的引入能够有效提高安全系数, 但对沉降影响较小;无加筋边坡与加筋边坡的破坏形式不同, 无加筋边坡坡肩垮塌, 而加筋边坡主要在1/6~1/3边坡高度处出现应力集中。
(
The stability of high and steep geosynthetic-reinforced slope and the reinforcement mechanism are researched through centrifugal model test and two-dimensional finite element method. Two centrifugal model tests are conducted in the purpose of exploring the failure trend or failure mode through measuring the variation of deformation and soil pressure of both unreinforced and reinforced slopes in stepped loading. Two-dimensional finite element model is established based on the fundamental parameters of the centrifuge model test. The calculation results are compared with the measured centrifugal test results to verify the rationality of the finite element model. Furthermore, the finite element model is employed to analyze the sensitivity of slope stability to the packing intensity and tensile strength of reinforced body. Results show that the geosynthetic reinforcement effectively improves the slope safety factor, but has slight influence on settlement. The failure mode of unreinforced slope differs from that of reinforced slope: collapse occurs at the unreinforced slope abutment, while stress concentrates at the 1/6-1/3 height of reinforced slope.
|
| [2] |
杨秀杰, 邓凯伦, 佘孟飞, 等. 分级加载下加筋边坡离心模型试验数值模拟[J]. 长江科学院院报, 2022, 39(2): 115-121.
针对西南地区某机场加筋边坡的离心模型试验,建立与离心试验尺寸一致的有限元数值模型,并采用考虑时间因素的Cvisc蠕变模型与M-C模型,模拟分级加载过程中离心模型的位移、土压力、筋材拉力随时间的发展和分布情况,并与离心模型试验结果进行比较。采用Cvisc模型研究了不同筋材长度,以及不同部位的筋材加密和筋材模量增加对加筋边坡的影响。研究结果表明:Cvisc蠕变模型能较好地描述变加速度加载的离心模型试验,引进时间因子能反映出不同时刻下离心模型的位移、土压力、筋材拉力;随着筋材长度的增加,潜在滑面后移,边坡稳定性提高;在1/3坡高处筋材拉力和水平位移最大,通过对1/6～1/2坡高范围内筋材加密或模量增加,是提高边坡稳定性最有效的方法,筋材加密效果优于筋材模量增加。
(
|
| [3] |
徐超, 廖星樾. 土工格栅与砂土相互作用机制的拉拔试验研究[J]. 岩土力学, 2011, 32(2):423-428.
(
|
| [4] |
杨广庆, 李广信, 张保俭. 土工格栅界面摩擦特性试验研究[J]. 岩土工程学报, 2006, 28(8): 948-952.
(
|
| [5] |
|
| [6] |
|
| [7] |
蔡晓光, 冯加煜, 刘巍巍, 等. 土工合成材料界面摩擦特性试验研究[J]. 建筑结构, 2025, 55(3):139-144,94.
(
|
| [8] |
|
| [9] |
|
| [10] |
|
| [11] |
张孟喜, 马原, 邱成春. 加强节点布置方式对双向土工格栅拉拔特性的影响[J]. 上海交通大学学报, 2020, 54(12):1307-1315.
随着土工加筋技术的发展，加筋材料形式趋向于三维化，通过在普通双向土工格栅横、纵肋交叉节点处布置一定厚度的加强块，形成了具有三维加筋效果的加强节点土工格栅，节点布置方式分为节点总厚度相等的上下双侧布置和上侧单侧布置两种方式．为了探索筋土界面之间复杂的相互作用机制，开展了一系列室内拉拔试验，探究了加强节点布置方式对筋土界面特性的影响，基于刺入剪切破坏理论分析了加强节点的作用机理并得到了极限拉拔阻力理论模型．结果表明：加强节点土工格栅的极限拉拔阻力与法向应力、节点厚度呈正相关关系．同一法向应力下，与普通土工格栅相比，两种节点布置方式工况的极限拉拔阻力均有一定程度的提高，提高率最高分别为118.33%和96.73%，表现为界面似摩擦系数、似黏聚力和综合摩擦角同时增加，且等节点厚度时上下双侧布置方式优于上侧单侧布置方式．基于刺入剪切破坏模式的理论值与试验值之间误差小于10%，加强节点显著提高了格栅的拉拔阻力．
(
|
| [12] |
张正, 刘振华. 土工格栅与黄土相互作用机制的拉拔试验研究[J]. 兰州工业学院学报, 2018, 25(1):1-6.
(
|
| [13] |
张文慧, 王保田, 张福海, 等. 双向土工格栅与黏土界面作用特性试验研究[J]. 岩土力学, 2007, 28(5):1031-1034.
(
|
| [14] |
李齐仁, 汪明元, 蔡剑韬, 等. 含水率对土工格栅与膨胀土界面拉拔性状的影响[J]. 岩土力学, 2010, 31(增刊2): 175-178.
(
|
| [15] |
蔡晓光, 刘巍巍, 沈冠豪, 等.一种土工合成材料的试验设备:中国, CN213689136U[P].2021-07-13.
(
|
| [16] |
ASTM D6706—01,Standard Test Method for Measuring Geosynthetic Pullout Resistance in Soil[S]. West Conshohocken: ASTM, 2013.
|
| [17] |
JTG E 50—2006, 公路工程土工合成材料试验规程[S]. 北京: 人民交通出版社, 2009.
(JTG E 50—2006, Test Methods of Geosynthetics for Highway Engineering[S]. Beijing: China Communications Press, 2009.(in Chinese))
|
| [18] |
张利阳, 易富, 李俊元, 等. 土工织物加筋尾矿砂界面力学特性试验研究[J]. 长江科学院院报, 2020, 37(5):145-150,156.
为研究土工织物加筋尾矿砂界面力学特性,在不同的尾矿砂含水率、试验拉拔速率和竖向压强下开展一系列土工布及土工格栅的拉拔试验。比较相同条件下的土工格栅与土工布拉拔试验结果可知:土工布对细粒尾矿砂的加筋效果优于土工格栅的加筋效果,竖向压强较大时两者的拉拔力峰值差值增大;随尾矿砂含水率增加,界面剪应力峰值明显减小,界面剪应力峰值在含水率1.2%时比含水率8.4%时增加50%以上,表观黏聚力先增加后减小,在最优含水率附近时达到最大,界面摩擦角先快速减小后缓慢减小;随试验拉拔速率增加,界面剪应力峰值缓慢增加,表观黏聚力先增加后减小,界面摩擦角先减小后增加;各工况下剪应力峰值均随竖向压强的增大而增大。研究结果可为土工织物加筋尾矿坝工程设计提供参考。
(
In order to study the mechanical properties of the reinforced interface between geotextile and fine tailings sand, we carried out pull-out tests on geogrid and geotextile under different test pull-out rates and different vertical pressures with varying moisture content of tailings sand. By comparing the pull-out test results of geogrid and geotextile under the same conditions, we conclude that geotextile has stronger reinforcement effect on fine tailings sand, and when vertical pressure is higher, the difference between the reinforcement effect on geotextile and geogrid is larger. With the rising of moisture content of tailings sand, the peak value of interfacial shear stress drops obviously: the interfacial shear stress at a moisture content of 1.2% is 1.5 times that when moisture content is 8.4%. Apparent cohesion increases at first but then decreases, with the peak value appearing near the optimal moisture content, whereas interfacial friction angle reduces rapidly at first and then declines slowly afterwards. With the augment of pull-out rate, the peak value of interfacial shear stress climbs slowly, and the apparent cohesion increases at first and then decreases, while the interfacial friction angle decreases at first and then increases. Under all working conditions, the peak value of shear stress increases linearly with the rising of vertical pressure.
|
| [19] |
肖成志, 路遥, 郑鸿, 等. 加筋土结构筋-土界面特性和筋材位移变化规律试验研究[J]. 土木与环境工程学报(中英文), 2024, 46(4):29-38.
(
|
| [20] |
易富, 杜常博, 王政宇, 等. 筋土界面特性宏细观分析试验仪器研制与应用[J]. 煤田地质与勘探, 2020, 48(1): 174-182.
(
|
| [21] |
刘昌禄, 邓荣贵, 顾垒, 等. 加筋土界面作用参数的拉拔试验研究[J]. 路基工程, 2014(6):77-81.
(
|
| [22] |
李乐. 静动荷载作用下土工格栅加筋机理研究[D]. 石家庄: 河北科技大学, 2022.
(
|
| [23] |
JTG D30—2015, 公路路基设计规范[S]. 北京: 人民交通出版社, 2015.
(JTG D30—2015, Specifications for Design of Highway Subgrades[S]. Beijing: China Communications Press, 2015.(in Chinese))
|
| [24] |
TB 10025—2015,铁路路基支挡结构设计规范[S]. 北京: 中国铁道出版社, 2015.
(TB 10025—2019, Code for Design on Retaining Structures of Railway Subgrades[S]. Beijing: China Railway Publishing House, 2015.(in Chinese))
|
/
| 〈 |
|
〉 |
