格宾网加筋红层软岩土石混填路堤力学行为的现场测试与数值模拟  

Field test and numerical simulation on mechanical behavior of red bed soil-rock embankment reinforced with gabion

作　　者：蒋建清[1] 杨果林[2] 

机构地区：[1]湖南城市学院土木工程学院,湖南益阳413000 [2]中南大学土木工程学院,湖南长沙410075

出　　处：《岩土力学》2016年第1期156-165,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.51308198);湖南省教育厅资助科研项目(No.14B034);湖南省交通科技项目(No.200612)~~

摘　　要：为掌握格宾网加筋红层软岩土石混填路堤的力学行为,通过加筋路堤现场测试研究路堤土压力、路堤内部潜在破裂面、格宾网筋材和石笼墙面变形等力学行为,并结合FLAC^(3D)数值模拟,分析格宾网加筋间距、加筋长度、地基土的压缩模量、强度指标及路堤填料压实度变化对其力学性状的影响。现场测试表明:格宾网拉应变沿路堤横断面非均匀分布,路堤内部潜在破裂面近似"改进双线段简化破裂面";石笼面墙在墙背平面内类似梁弯曲变形,在墙背平面外以向外鼓胀变形为主;墙后同一标高处填土竖直土压力呈非均匀分布;墙背实测水平土压力与墙高呈非线性关系,路堤填筑高度大于7.5 m时,墙背水平土压力接近朗肯主动土压力值。数值模拟表明:加筋间距及长度变化对路堤侧移的影响明显大于对沉降的影响,格宾网竖向加筋间距宜为0.5~1.0 m,水平加筋长度宜为0.7H^1.0H;地基土压缩模量改变对路堤沉降有较大影响,为控制路堤不均匀沉降,地基土压缩模量宜大于5 MPa;为控制墙面侧移增长速度,地基土黏聚力不小于15 kPa;红层软岩土石混填路堤填料压实度宜控制在93%以上。To understand the mechanical behaviours of red bed soil-rock embankment reinforced with gabion, field tests are conducted to obtain soil pressure, the deformations of gabion reinforcement and gabion wall and the potential internal fracture surface. Meanwhile, based on in-situ tests and FLAC^（3D） numerical modelling, a comprehensive analysis is performed to investigate the effects of reinforcement spacing, reinforcement length, compression modulus, strength indicators of foundation soil and compaction of embankment fill on mechanical behaviours of the embankment. Field tests indicate that the tensile strain distribution of gabion reinforcement along the cross-section of embankment is non-uniform. Besides, the internal potential failure surface of embankment is similar to ‘improved simplified double-segment rupture surface＇. The deformation of gabion wall tends to be beam bending inside the back plane of gabion wall, whereas external-oriented bulging is outside the back plane of gabion wall. It is found that the vertical earth pressure in backfill at the same level behind the wall exhibits non-uniform distribution. The relationship between the measured earth pressure at the back wall and the height of the wall is non-linear. When the filling height of the embankment is greater than 7.5 m, the horizontal earth pressure along the back wall can refer Rankine active earth pressure value. From numerical simulation, it can be noticed that the effect of the reinforcement spacing and length on the lateral displacement of embankment is significantly greater than on the settlement. As a result, the vertical spacing and horizontal reinforcement length of the gabion reinforcement should be recommended as 0.5-1.0 m and 0.7H-1.0H, respectively. Since the changes in the compression modulus of foundation soil have a significant effect on the embankment settlement, the compression modulus of foundation soil approaches to be greater than 5 MPa for controlling embankment uneven settlement. In the aim of controlling the growth

关 键 词：加筋土 红层软岩土石混填路堤 力学行为 现场测试 数值模拟 

分 类 号：TU473.1[建筑科学—结构工程]