Research On The Rupture Characteristics And Mechanism Of Locking Solids Of Landslide With Wall-like Locked Segment

Due to the specific geographical environment and climatic conditions,slope disasters are frequent in China.In 2019 alone,as many as 4,220 landslide disasters occurred across the country,accounting for 68.27% of the total number of geological disasters.It has caused huge losses to people’s lives and properties.In order to avoid and reduce the losses caused by slope disasters.It is important to reveal the mechanism of landslide instability,establish effective monitoring methods,early warning methods and improve the level of slope prevention and control.The landslide with wal-like locked segment is an important type of locking slope.The wal-like locked segment plays a decisive role in the stability of landslide with wal-like locked segment.If the rupture characteristics,rupture mode,rupture mechanism and rupture dynamics of the locking solids can be revealed.It is of great significance to reduce the instability loss of such slopes.This paper took the locked segment of the landslide with wal-like locked segment as the research object.The rupture mode,rupture mechanism,rupture process,rupture mechanical characteristics and rupture acoustic emission characteristics of the lock solid were studied through model tests,numerical simulations and theoretical analysis.Laser vibration measurement technique was used to reveal the rupture dynamic characteristics of lock solids.The dynamic characteristics of locking solids during instability of wall-locking slopes were revealed.The rupture characteristics of retaining wall locking slopes during instability were revealed.The main research contents and results included the following aspects.(1)The geological characteristics,instability characteristics and instability mechanisms of actual landslide with wal-like locked segment were collected and analysed.The composition of the Xikou landslide was characterised by a double layer of hard upper and soft lower structure.The locking section acted as a retaining wal,carrying most of the loads transmitted by the upper slope along the potential slip surface.Under the long-term loading of the upper slope,the weak foundation was deformed in the free direction by creep.This increased the degree of loading on the rock in the locking section.If the concentrated stress was greater than the long-term strength of the locking section,the locking section will suddenly fractured in a brittle manner.This leaded to landslides.The instability dynamics of landslide with wal-like locked segment was discussed.(2)The fracture processes,fracture patterns,fracture mechanics and fracture penetration patterns of fracture-locked solids with different fracture patterns,different grain size compositions and different length levels were revealed.The rupture process,rupture mode and rupture mechanics of locked solids under different axial pressures were revealed.The rupture mechanism of the locked solids with different fracture patterns were revealed.Five penetration modes for different fracture-locked solids were revealed by indoor compression shear tests.The locked solids with different fracture modes had different mechanical characteristics.The first,fourth fracture mode locking solids were brittle fracture.The second,third,fifth and sixth fracture pattern lock solids were progressive fracture.The fracture initiation point and rupture pattern of locked solids with different grain size compositions were different.The peak shear force of the locked solids consisting of the three grain sizes and their corresponding shear displacements were maximum.Experiments have shown that when horizontal fissures were long,the locking body was the first to produce cracks that extended from the top towards the tip of the horizontal fissure.When the horizontal fissures were short,the locking body was the first to crack at the tip of the fissure and in the middle of the rock mass.The longer the horizontal fissure,the greater the strength damage to the locking solid.The higher the axial pressure,the more the locking solid tended to expand downwards.The lower the axial pressure,the more the locking solid tended to expand horizontally.Locked solid rupture shear diagram and locked solid rupture displacement vector diagram revealed the locked solid rupture mechanism.(3)The acoustic emission characteristics of fracture of locked solids with different fracture patterns,different grain size compositions and different length levels were revealed.The change of acoustic emission characteristics reflected the crack evolution state of the locked solid.With crack generation,the stress will decrease and the acoustic emission characteristics will increase.The acoustic emission characteristics of the locked solid were strongest when the peak shear formed a macroscopic crack.The acoustic emission signature increased again when the lock solid developed a secondary rupture after peak shear.As the lock solid entered the residual strength phase,the acoustic emission is characterised by a sawtooth shape due to the friction between the ruptured lock solids.When the lock solid was completely ruptured,the strength was very weak and the acoustic emission signature was weak.There were five patterns of acoustic emission characteristics for the different lock solids.(4)The variation of dynamic characteristic parameters with rupture for different hardness fissure-free locked solids,different hardness fissure-locked solids,different length fissure-locked solids and fissure-locked solids under different axial pressure were revealed.When the locking solid was initially compacted,its frequency will increase.Until it reached its critical rupture point,the lock solid started to produce internal microcracks and the lock solid frequency started to drop rapidly.This was used as a precursor feature for the rupture of the locking solid.When the locking solid was low in strength,microcracking occured after the locking solid has reached its critical rupture point.The microcracks will rapidly develop into large cracks,causing the lock solid to shear off.The moment of critical rupture of the lock solid and the moment of shearing almost coincided.The greater the axial load applied to the locking solid,the greater the frequency of increased in the locking solid.The lock solid reached its critical rupture point more quickly.The fracture length of the lock solid had little effect on the initial frequency of the lock solid.(5)The rupture dynamic characteristics of the locking solid were verified.The unstable rupture characteristics of landslide with wal-like locked segment were revealed.Using the Sichuan Xikou landslide as a prototype,a similar scaled-down model was established in the chamber.The instability of the the landslide with wal-like locked segment was simulated by applying axial loads to the indoor test model.A laser vibrometer,strain gauge,extensometer and video camera were also used to monitor the whole process of slope instability.The tests showed that the change in the dynamic characteristics of the locking solids during the instability of the retaining landslide with wal-like locked segment was consistent with the results of previous studies.The destabilisation rupture characteristics of the landslide with wal-like locked segment were revealed.The characteristics of the change of axial load and axial displacement during the instability of the landslide with wal-like locked segment were revealed.The characteristics of slope strain during the instability of landslide with wal-like locked segment were revealed.