堆体边坡根土复合体抗剪强度试验研究  

Root-soil Complex Body Shear Strength Tests Study of Debris Slope

作　　者：程磊[1] 张生旭[2] 郝延周[3] 宋前进[1] 

机构地区：[1]中国地质大学(北京)工程技术学院,北京100083 [2]河南农业大学烟草学院,郑州450002 [3]西安建筑科技大学土木工程学院,西安710055

出　　处：《科学技术与工程》2017年第23期256-265,共10页Science Technology and Engineering

基　　金：中国地质调查局计划项目(12120114029801)资助

摘　　要：经生态修复的堆体边坡多位于城镇生态涵养带和水源保护区,在降雨侵蚀作用下坡体浅层失稳现象严重,不同类型植被根系对土体强度指标影响的定量化是亟待解决的问题之一。以伊洛河流域粉黏土堆体边坡为例,量测单位样方内狗牙根及沙棘的植株高度、植株密度,调查土层深度20~30 cm、直径0.0~1.0 mm的狗牙根根系,调查深度40~50 cm、直径1.0~2.0 mm的沙棘根系,测量整理根长量、根体积、根系密度,确定加入土体中的根系直径及重量,测取各覆被条件下土样常规物理力学指标,采用GDS三轴试验仪对重塑根土试样开展一系列不固结不排水三轴试验,分析试样破坏荷载、根系强度影响系数、抗剪强度指标增长率。试验结果显示:相同围压下各根土复合试样破坏荷载均大于素土试样破坏荷载,狗牙根土试样、沙棘根土试样、狗牙根沙棘根土试样的破坏荷载约是素土试样破坏荷载的倍数依次为1.29~1.35倍、4.52~4.79倍、4.68~4.95倍;狗牙根根系强度影响系数随着围压的增大而减小,而含有沙棘根系试样的根系强度影响系数随着围压的增大而增大;含根系土试样的抗剪强度包络线均位于素土试样抗剪强度包络线上方,狗牙根根系对土体抗剪强度指标的改善主要体现在黏聚力上,而含沙棘根系土试样的黏聚力与内摩擦角均有相对更大幅度的提高;狗牙根土试样黏聚力增长率为35.63%、内摩擦角增长率为16.24%,沙棘根土试样黏聚力增长率为219.13%、内摩擦角增长率为254.02%,狗牙根沙棘混合土试样黏聚力增长率为224.88%、内摩擦角增长率为261.64%。不同类型根系对土体强度的贡献值是不同的,沙棘根系大于狗牙根根系。Debris slope by ecological restoration located in urban ecological conservation and water conservation was more than other. It＇s shallow instability phenomenon was usual while rainfall load. One of the most important problem to be solved that quantitative of different type vegetation roots influence on soil strength. Clay debris slope in the Yiluo River basin as an example,the plant height and plant density of Bermuda grass and Sea-buckthorn were measured in quadrat. Investigation Bermuda grass root that soil depth 20 ~ 30 cm and diameter 0. 0 ~ 1. 0mm.Investigation Sea-buckthorn root that soil depth 40 ~ 50 cm and diameter 1. 0 ~ 2. 0 mm. Measuring amount of root length and root volume and root density. The root diameter and weight in soil was determined. Routine physical mechanical indexes acquisited from different cover conditions. Carried out a series of unconsolidated undrained triaxial shear test to contain roots remoulded soil samples by GDS triaxial test apparatus. The sample failure load,root strength coefficient and growth rate of shear strength were analyzed. Experimental results show that failure load of each root-soil composite sample were greater than the failure load of plain soil under the same confining pressure.The failure load times that Bermuda grass soil sample and Sea-buckthorn soil sample and Bermuda-buckthorn soil sample is about 1. 29 ~ 1. 35 and 4. 52 ~ 4. 79 and 4. 68 ~ 4. 95 than plain soil,respectively. Root strength influence coefficient of Bermuda grass roots decreases with increasing of confining pressure,however,the Seabuckthorn roots reversed. Shear strength envelope containing roots soil sample which both are located in upward side of plain soil shear strength envelope. Cohesive force and internal friction angle have more improved relatively which contained Sea-buckthorn roots soil sample. Cohesion growth rate 35. 63% and internal friction angle growth rate16. 24% of Bermuda grass sample. Cohesion growth rate 219. 13% and internal friction angle growth rate 254. 02%of Sea-buck

关 键 词：堆体边坡 狗牙根根系 沙棘根系 三轴试验 抗剪强度 

分 类 号：TU411.3[建筑科学—岩土工程]