Research On Road Performance Of Mudstone Filler In Coupled Field

Existing research shows that the shale filler has the collapse under the influence of water,reduce the properties such as compressive strength,the use of these properties directly affect it as subgrade filling performance,especially in the complicated water environment,strong seepage field and many field coupling factors such as high load,the ground water pressure,seepage path will produce change,change in effective stress in subgrade soil.Therefore,under the action of multi-field coupling factors,the water environmental failure mode of mudstone embankment is essentially different from that of common soil,and the conventional roadbed treatment process is not enough to show the failure characteristics of mudstone embankment in multi-field coupling environment.However,due to the lack of research on the deformation law of mudstone filling subgrade in the process of seepage field evolution,the design basis is not sufficient,and the construction cost increases.Therefore,how to fundamentally identify the root of the problem and take targeted construction measures has become an urgent problem to be solved by researchers and highway builders.By means of theoretical analysis,physical test and numerical simulation,this study systematically studied the physical and mechanical properties of mudstone subgrade filling under the action of multi-field coupling factors,slope stability in backfill area and early warning application.Firstly,the basic physical and mechanical properties of mudstone fillers,especially the road performance indexes under the influence of water environment,are systematically analyzed through laboratory tests,and the road suitability of mudstone fillers is preliminarily obtained.Secondly,based on the index parameters obtained under different conditions in laboratory tests,relying on COMSOL Multiphysics finite element software,the stability of mudstone filled embankment slope under different field conditions was analyzed,and the deformation law of mudstone slope under the coupling action of stress field and seepage field was obtained.Finally,the in-situ test monitoring method is adopted,and the deformation law of mudstone filling obtained by finite element simulation is compared with the test data collected in the field.The application research on the stability of mudstone filling roadbed slope is carried out,and a safety early warning system suitable for mudstone filling roadbed slope is established.The main achievements of this paper are as follows:(1)Through the indoor point load test and bearing ratio test,the uniaxial compressive strength and bearing ratio of mudstone filler under different water environments are studied.It is found that the uniaxial compressive strength of mudstone filler specimen decreases gradually with the increase of water content in a quadratic function.Through the fitting curve,the minimum uniaxial compressive strength of mudstone filler specimen is 5.88 MPA,which is judged as soft rock according to the standard for engineering rock mass separation;With the increase of water content,the bearing ratio of mudstone filler specimen decreases slowly in an exponential function to 5% and remains unchanged.The indoor test research shows that the physical and mechanical properties parameters of mudstone filler meet the requirements of relevant regulations.(2)Based on COMSOL multiphysics finite element software,the slope stability of mudstone filled subgrade with different filling properties and slope characteristics under stress field is analyzed,and the variation trend of slope stability safety factor of mudstone filled subgrade is obtained.The research shows that the safety and stability coefficient of mudstone subgrade slope gradually decreases from 2.76 to 1.50 and decreases by 46% with the increase of water content from 9.0% to 17.0%;With the increase of compaction degree from 90% to 98%,the linear development trend gradually increases from 2.76 to 3.58,an increase of 29%;As the slope ratio increases from 1:3 to 1:0.5,the development trend of exponential function decreases from 3.85 to 1.87,reducing by 51.43%;As the slope height increases from 1.5m to 7.0m,the linear development trend decreases from 2.76 to 2.62,a decrease of 5.07%.It is found that by controlling the moisture content of mudstone filler below 21.19% and strictly controlling the compactness of mudstone filler,the stability of mudstone filler subgrade slope under the action of stress field can fully meet the requirements of relevant specifications.(3)The pore water pressure,horizontal and vertical displacement of mudstone filled subgrade slope under the coupling of seepage field and stress field are systematically analyzed.The results show that with the increase of rainfall intensity,especially after the rainfall intensity reaches 70 mm / D,the mudstone filling subgrade slope gradually tends to be saturated under the influence of rainfall infiltration,the pore water pressure of mudstone filling subgrade slope gradually increases,and the water contact intensity of mudstone filling decreases rapidly,which makes the horizontal and vertical displacement of mudstone filling subgrade slope increase rapidly,but the total displacement does not exceed 1mm,which meets the requirements of road performance index.(4)The change law of safety and stability of mudstone filled subgrade slope in the evolution of seepage field in the coupling field is obtained by simulation.It is found that when the rainfall duration is 48 h and the rainfall intensity increases from20 mm / D to 210 mm / D,the stability safety factor of mudstone filled subgrade slope decreases from 3.10 to 2.93;When the rainfall intensity is 200 mm / D and the rainfall duration increases from 8h to 48 h,the safety factor of slope stability decreases from3.03 to 2.93;When the rainfall is 420 mm,the mudstone filling subgrade slope is20 mm / D,3.07 at 21 d,and 2.93 at 210 mm / D,which meets the requirements of road performance indicators.At the same time,through the simulation research on the limit horizontal displacement of mudstone filling subgrade slope in the basic stable state,under stable state and unstable state under the action of stress field,the road performance threshold of mudstone filling under the action of coupling field is obtained,which lays a foundation for the establishment of mudstone Road early warning system.(5)Based on the field in-situ test research,the basic parameters such as force and displacement in mudstone subgrade are obtained,compared with the simulation threshold in coupling field,and the road early warning system of mudstone subgrade is established.The in-situ monitoring of mudstone filling subgrade slope is carried out by using gyroscope and interlayer gyroscope,and the horizontal displacement and angle change of mudstone filling subgrade slope are collected.At the same time,when the rainfall intensity is moderate rain and the rainfall duration is 12 h,it is compared and analyzed with the simulation results.The results show that the error between the inclinometer monitoring data and the simulation results is kept within0.01 mm,The error between the gyroscope monitoring data and the simulation results is kept within 0.001 °,which fully meets the practical performance requirements.Therefore,the numerical simulation results in the coupling field can be used as the early warning threshold of mudstone filling subgrade slope,and based on this,the early warning system of mudstone road performance is constructed.