Research On The Water Feature Of Carbonaceous Mudstone-soil Stratified Filling Embankment Under Unsaturated Seepage

The structure of carbonaceous mudstone-soil stratified filling embankment is one of the widely application forms in carbonaceous mudstone distribution regions. However, after long-term field monitoring, it shows that the above filling embankment method is not ideal, the stratified filling embankment instability phenomena caused by rainfall infiltration often occurs. Therefore, the research on embankment water feature under rainfall infiltration has important practical value. Based on results of previous studies, there is a study on infiltration law and water features by designing indoor rainfall test model. Meanwhile, differences in the degree of compaction case are studies; Aiming at extreme rainfall in Liuzhai, Guangxi, Edging thickness and shallow drainage system of carbonaceous mudstone-soil stratified filling embankment are studied. The main results of this paper are as following:(1) The feasibility about indoor test method, test model and related test equipment is verified by designing different test conditions. In terms of carbonaceous mudstone-soil stratified filling embankment, embankment internal rainfall infiltration law is consistent under different degree of compaction. The bigger embankment compaction degree, the longer the time of feature points at same position in response to changes in moisture content and reach saturation, the smaller the lateral and vertical infiltration rate of infiltration rate. Changes in the embankment internal moisture content are closely related to their position. In rainfall process, the main area affected by rainfall infiltration focus on the following embankment, the soil following pavement is not affected by rainfall infiltration.(2) Aiming at extreme rainfall which has continuous rainfall of 21 days in Liuzhai,Guangxi, The depth of carbonaceous mudstone-soil stratified filling embankment affected by rainfall is at 2.5m～3.0m. Through a comprehensive analysis, the final edging thickness of carbonaceous mudstone-soil stratified filling embankment should be not less than 2.6m.(3) Through the different slope shallow drainage scheme, it shows that setting shallow drainage system in tipping layer could effectively improve the distribution of embankment internal moisture content. The longer the drainage pipe, the better the drainage effect. Aiming at extreme rainfall which has continuous rainfall of 21 days in Liuzhai,Guangxi, The best arrangement of slope shallow drainage system is arrangement of the condition seven which drainage pipe is 4.0m. Finally, reasonable drainage measures are designed for the shallow drainage of carbonaceous mudstone-soil stratified filling embankment, they are slope double-wall gravity drainage and slope shallow drainage system.