Study On The Uncoordinated Dynamic Response Of Geological Bodies With Weak Intercalation

This study investigated the Daguangbao landslide geological conditions and interlayer rock mass characteristics,and the interlayer cataclastic rock physical experiments and strength test were carried out to obtain the physical and mechanical parameters of the rock in daguangbao landslide interlayer.With the help of those analysis,the mechanical properties of the rock mass in the interlayer of the landslide are analyzed.With the help of existing research results of the predecessors,this paper supplements the parameters needed for the establishment of the similar model of the shaking table test,and calculates the physical and mechanical parameters of the similar materials and the formula of the similar materials.After that,we determined the shaking table experimental scheme,established the generalized model,arranged the sensor,and loaded different types of seismic waves.Based on the experimental results,the response laws of the acceleration,stress and displacement at different layers of the model under seismic load and the influence of the change of seismic wave on the response laware were analyzed.The conclusions are as follows:(1)The shear strength of the rock mass in the interlayer of Daguangbao landslide is reduce from the upper to the lower and the shear strengh of the mud belt on the bottom of the interlayer is lowest which means the shear strength of rock mass decreases with the increase of crushing degree.In the process of earthquake,the vibration load will make the interlayer rock mass further broken down,and then the strength will be greatly reduced which will make the possibility of landslide instability increased.In addition,the effect of water content on the shear strength of the clay belt is obvious.With the increase of water content,the shear strength decreases exponentially,and the cumulative deformation of the failure of the clay layer is greatly reduced.All of those will greatly increase the possibility of landslide start.(2)In the geologic body with soft interlayer,the acceleration response value of the upper rock mass will show an elevation amplification effect.Under the vertical seismic wave,the acceleration response value of rock mass in the interlayer will be less than the response values of rock mass in the other layers,which will cause the uncoordinated response of accelerate.In the case of horizontal seismic wave loading,the values of the acceleration response of different layers is not consistent.It will also cause the uncoordinated response of accelerate.The increase of the frequency or amplitude of seismic wave will increase the difference of the acceleration response in the whole direction of the interlayer,and the effect of the horizontal wave which has the same intensity with vertical wave is more obvious.(3)Under the loading of both horizontal wave and vertical wave,the soil pressure of the rock mass in the interlayer can be several times of the pressure of the rock mass in the other layers.This shows that the stress value of rock mass in the interlayer of the geologic bodies with weak intercalation under the earthquake is significantly greater than the rock mass in the other layers,and this makes the rock mass in the soft interlayer more vulnerable to be damaged than the other high strength rock mass in the earthquake.What's more,with the increase of the frequency or amplitude of seismic wave,the value of earth pressure in each layer of the geological body will increased significantly.(4)The strain of the rock mass in the weak layer is obviously greater than that of the other layers,and the magnitude of the displacements of the rock mass in different layers are not consistent,all of that make the deformation amount of weak interlayer increase and decrease cyclically.That produces a cyclic dynamic load in the vertical and horizontal directions,increasing the probability of failure.With the increase of the frequency of seismic wave,the uncoordinated strain of soft layer will be increased,and the probability of failure of rock mass in the weak intercalation may be increased.The higher the amplitude of seismic wave in the horizontal direction,the higher the deformation of the soft layer and the uncoordinated strain of the geological body with weak intercalation,and the rock mass in the intercalation is more likely to be damaged.But in the vertical direction,the relationship between the degree of uncoordinated strain and the seismic amplitude is not monotonous.For a certain frequency of seismic wave,there is a value of seismic amplitude can lead an relatively high risk,but for higher frequency seismic waves,this value is higher.On the whole,the vertical seismic wave with both high frequency and high amplitude will produce more significant uncoordinated strain,which will aggravate the instability of geological bodies with weak intercalation.(5)Under the influence of seismic wave,the dynamic response of the Daguangbao slope is uncoordinated due to the existence of weak interlayer.For the acceleration response,the slope body has a significant elevation amplification effect,which results in the increase of the sliding force of the landslide.For the stress response,the stress value in the rock mass of Daguangbao landslide interlayer is significantly higher than that of other layers.Because of the large fragmentation and low strength of the interlayer disturbed rock mass,it will be the first failure,and the sliding surface will be formed,which will lead to the sliding of the landslide.The fragmentation degree of rock mass in the interlayer is higher,and the strength of the mud belt will decrease sharply with the increase of water content during the earthquake,all of that exacerbated the destruction of this layer.For strain response,the strain value of rock mass in the interlayer is more than that of other layers,and the uncoordinated of the displacement in different layers aggravated the interlayer rock fragmentation,increase the possibility of damage.What's more,the seismic wave which induced the Daguangbao landslide has the characteristics of high frequency and high amplitude.These characteristics of seismic waves have increased the uncoordination of the dynamic response of each layers of the landslide,which greatly increased the possibility of instability slide.