Study On The Influence Of Rock Mass Degradation On The Interaction Of Pile-layered Rock Mass Under The Condition Of Excavation

The two factors that keep the slide-resistant pile resist the slide effectively are the stability of rock mass before pile and the enough intensity of the pile body. But under the condition of large excavation before the pile, no study exists so far in the area in which whether the rock mass before pile can keep the cantilever pile work effectively and assure the slide stable. This paper mainly studies on the interaction mechanism between the pile and stratified rock mass under the evacuation of the stratified rock mass before the pile. Take a certain slide for example, based on the analysis of the geological conditions of the stratified rock mass project before the pile, the statics parameters of rock and soil mass acquired from the indoor field test, and computational theory of deformation and internal force of piles through elastic foundation beam method, namely "M" and "K". By carrying out the model test and on the basis of studying the different thickness, tendency and intensity of the stratified rock mass, the distribution law of the interactive force between rock mass before pile and slide-resistant pile is observed. The appropriate geology-numerical-mechanical model is established under the background of understanding the mechanics characteristic deformation law and break mechanism of the stratified rock mass. This model helps to fur ther demonstrate the Interactions between anti-slide pile and layered rock under the condition of large evacuation. The research achievements is in the following:(1)Based on rock mass mechanics, structural mechanics, elastic-plastic mechanics and so on, and the design theory of the slide-resistant pile embedded in intact rock mass, the mechanical characteristic, deformation law of the slide-resistant pile and the interaction between the pile and stratified rock mass under the situation of evacuation before pile are analyzed. At last, the interactive relationship between the slide-resistant pile and stratified rock mass, and the deformation law of stratified rock mass is ascertained, which is related to the buried depth of the slide-resistance pile and the intensity, tendency and thickness of the rock stratum.(2) According to the main physical and mechanical parameters from certain slide prototype, the similar model test method is carried out indoors. Simple variable method is used to study the deformation law of stratum rock mass before pile and the interactive distribution law between stratum rock mass before pile and the slide-resistance pile under the condition of different thickness, tendency and intensity of the rock mass. The conclusion is in the following:?In any case, the displacement of layered strata increases as load gains, and the displacement decreases from the bottom to the top. The displacement value of the monitoring point of soil behind piles varies as the load changes but also increases as the load gains.?The break patterns are different in each condition, And the common laws have been found that under the function of force, the slide-resistance moves forward, leading to the crevice of rock mass behind the pile, thus, the fracture appears.?Every time the pressure curve declines, it is shown that break appears in the inside rock mass. The larger the declined value is, the more obvious the break is. The greater frequency of decline progress is, the more violent break arises in the monitoring point areas.(3) According to the main physical and mechanical parameters from certain slide prototype, the similar model test method is carried out indoors. Simple variable method is used to study the deformation law of stratum rock mass before pile and the interactive distribution law between stratum rock mass before pile and the slide-resistance pile under the condition of different thickness, and tendency of the rock mass. The conclusion is in the following:?The influence of the soft layer:As the number of soft layer gains, the displacement value of various conditions increases, meanwhile, the break is more obvious.?The study on break pattern:As for the horizontal stratum, as the thickness decreases, the break evolves to the pile bottom gradually. As for the rock stratum whose cisoid dip angle is 450, the break mainly arises at the vertical direction, and slightly appears at the horizontal direction. The rock stratum mainly slides toward bottom left. As the thickness of the rock stratum decreases, the displacement value increases gradually, which explains when the break is more severe, the model becomes unstable increasingly. As for the rock stratum whose reverse dip angle is 450, the phenomenon is that the whole rack stratum slides while the break inside the rock is rather small. The main reason is that under geostatic stress, the rock stratum has the tendency to slide downward. The slide-resistance effect of the pile is not obvious. As the thickness of rock stratum declines, the displacement value increases gradually, which shows when the break is more severe, the model becomes unstable increasingly.Based on the research achievement above, it is acquired that the degradation of stratum rock mass before pile influences the interaction between the slide-resistance pile and the rock stratum, which can provide scientific reference for the design and construction of the rock stratum slide project, of which the bed rock is stratiform.