Study Of Instability Mechanism And Intelligent Pre-warning For Cutting Slope With Soil-rock Binary Structure

The cutting slope with soil-rock binary structure(abbr.binary slope)is one kind of slope that consists of overlaying soil and bottom rock mass,which is relatively common during the road building in mountainous area and hilly area.Under the influence of rainfall as the main factor,binary slope is easy to evolve into landslide,bring about financial loss,casualties,construction interruption,traffic jam and ecological damage to some extent.For this purpose,on the basis of exploring instability mechanism of binary slope,doing intelligent pre-waring is the key and development tendency to prevent this kind of slope disaster.Taking the binary slope along Shuang’da highway as the study object,this paper studied the instability mechanism and intelligent pre-waring by using field investigation and test monitoring,generalization and summarization,laboratory test,theoretical analysis,numerical modeling and software programming,and obtained the following main results and conclusions:(1)The change rules of temperature and humidity in the binary slope were revealed via field monitoring and detection of temperature and humidity of binary slope,the fact that water infiltration is the sensitive impact factor of stability for binary slope was obtained,and the infiltration model of water in the overlying soil of binary slope was put forward.(2)The change rules between shear resistances of the overlying soil,fully weathered rock mass,and contact surface of soil-rock for binary slope and humidifying process were revealed based on laboratory triaxial and direct shear tests.For the other types of weathered rock mass at the bottom of binary slope,compression strength of rock block,geological strength index,deformation modulus of rock block were reduced syncheronously which was used to simulate the implication of moist environment based on field research and theoretical analysis,and the long-term deteriorating law of property parameters of rock mass with moist environment was explored.(3)Based on centrifugal model test,numerical simulation analysis and stability analysis,the failure mechanisms of binary slopes with slight inclined,steep inclined and anti-inclined contact surface due to slope height increasing and water infiltration were revealed,and the internal boundary of sensitive soil layer affecting the stability of binary slope under water infiltration was obtained.(4)Based on the comparative analysis of change rules of the same kind of monitoring variables with safety factor of slope,the monitoring sensitive sites of multi-source monitoring variables(single point displacement on the slope surface,concrete strain of lattice girder,relative displacement between two points,axial force of anchor,tensile force of anchor cable,and gradient)for three types of binary slopes were obtained,and the variation pattern types of monitoring variables were concluded.(5)Empirical method,rehearsal-regression analysis method,and rehearsal-support vector machine method were put forward to be used to determine the four-level pre-warning values of every monitoring variable via experience summary and theoretical analysis,and the standard used to issue four-level pre-warning was provided.(6)Through software programming,the cloud platform and APP for intelligent prewarning of roadbed slope with convenient human-computer interaction were developed obeying following access order: project,slope object,slope fa?ade and its surface monitoring points,slope section and its internal monitoring points,which can be used to do real-time remote monitoring of multi-source parameters and automatic pre-warning of potential risks of slope.(7)A case study of remote monitoring and pre-warning for binary slope was put out.The results of the case study was used to verify the effectiveness of intelligent pre-warning APP and cloud platform of slope,reveal the dynamic response laws of inclined relative displacement between two points,axial force of anchor,and concrete strain of lattice girder with rainfall and air temperature,and evaluate the dynamic stability of the slope.The research results can provide useful reference for the intelligent pre-warning work of binary slope,and are conducive to speed up development of intelligent pre-warning of roadbed slope and intelligent highway.