摘要
非饱和膨胀土地区的梯田埂坎稳定性差以及垮坎是农业坡改梯工程建设中最棘手的问题。本文基于BISHOP的非饱和土抗剪强度理论,首先,计算了天然非饱和状态下PP织物袋坎墙土压力;然后,分析在雨水逐层入渗条件下墙后膨胀土自由完全膨胀时坎墙的稳定性;最后,基于温度场的热胀作用等效模拟膨胀土的吸水膨胀作用的方式,对降雨作用下PP织物袋坎墙及墙后填土膨胀特性进行了数值模拟与评价,并对比分析了数值结果及理论解析结果的异同。研究结果表明:在天然非饱和状态下,墙后膨胀土拉张区深度大于坎墙高度,坎墙未受到土压力作用。雨水逐层入渗、墙后膨胀土水平自由完全膨胀条件下,当雨水入渗至临界饱和深度时,膨胀变形释放导致坎墙因发生过大的位移而破坏。理论解析中未考虑墙后膨胀土的竖向膨胀效应,而数值模拟中充分考虑了墙后膨胀土的多向膨胀效应,数值模拟分析得出坎墙破坏时的临界饱和深度明显大于理论解析的结果,因此数值模拟结果比理论解析结果更接近实际情况。
Poor stability of the ridge of terraced field and collapse of the ridge are the most intractable problems in the construction of the project of terracing slope cropland within the region of unsaturated expansive soil.Based on BISHOP s unsaturated shear strength theory,the earth pressure of the ridged-wall built with PP bag(polypropylene geotextile bag)under the natural unsaturated state is calculated herein at first,and then the stability of the ridged-wall during the complete free expansion of the expansive soil behand the wall under the condition of the layer-by-layer rainwater infiltration is analyzed.At last,the numerical simulation and evaluation on the expansion characteristics of both the ridged-wall of PP bag and the backfill soil behand the wall under the effect of rainfall are carried out in accordance with the mode of equivalently simulating the wet-expansion effect of the expansive soil on the basis of the thermal expansion effect of temperature field,while the similarity and difference between the numerical result and the theoretical analysis result are comparatively analyzed as well.The study result shows that under the natural unsaturated state,the ridge-wall is not affected by earth pressure if the depth of the tensional area of the expansive soil behand the wall is larger than the height of the ridge-wall.When rainwater infiltrates to the critical saturation depth,the ridge-wall is to be failed due to the overlarge displacement caused by the release of the relevant expansive deformation under the condition of the complete horizontal free expansion of the expansive soil behand the wall.The vertical expansion effect of the expansive soil behand the wall is not considered in the theoretical analysis,while the multi-directional expansion effect of the expansive soil behand the wall is fully considered in the numerical simulation,from which the result of the critical saturation depth during the failure of the ridge-wall obtained from the numerical simulation is obviously lager than that from the theor
作者
董鑫
霍旭挺
李荣建
骆晗
任双宏
张媛
DONG Xin;HUO Xuting;LI Rongjian;LUO Han;REN Shuanghong;ZHANG Yuan(China United Northwest Institute for Engineering Design and Research Ltd.,Xi an 710077,Shaanxi,China;Institute of Geotechnical Engineering,Xi an University of Technology,Xi an 710048,Shaanxi,China;Power China Northwest Engineering Corporation Limited,Xi an 710065,Shaanxi,China)
出处
《水利水电技术》
北大核心
2019年第7期209-215,共7页
Water Resources and Hydropower Engineering
基金
国家自然科学基金项目(11072193)
陕西省黄土力学与工程重点实验室项目(14JS064)
陕西省科学技术厅(S2018-ZC-TD-0105)
关键词
梯田埂坎
非饱和膨胀土
PP织物袋坎墙
降雨作用
数值模拟
膨胀效应
ridge of terraced field
unsaturated expansive soil
ridge-wall of PP bag
rainfall effect
numerical simulation
expansion effect
