Study On Dynamic Mechanism Of Interaction Betweeen Cutting Rock Slope With Prestressed Anchor Cable Structure During Strong Earthquakes

Based on the investigation of cutting slope damage caused by the Wenchuan 8.0 earthquake in Sichuan Province, the author mainly summarizes the anchored cutting slope earthquake damage. On the basis of getting the shear strength parameters of interface between mortar and rock through direct shear tests, and in conjunction with the results of anchored cutting slope earthquake damage investigation, dynamic interaction mechanism of cutting rock slope with prestressed anchor cable structure is calculated and analyzed. The main work content and results are as follows:1) The analysis of the cutting slope earthquake damage investigation shows that slope reinforced by anchor structure has better seismic performance.2) Through direct shear tests, simulation of the shear failure process of bonding interface between mortar and rock is carried out. Analysis of influencing factors of the peak strength and the influencing rule of sand cement ratio on shear bond strength of mortar to rock is carried out. The residual angle and the residual cohesion are greater while in the sand cement ratio of 0.75 and 0.50 respectively. Shear strength parameters of mortar to three types of rocks are obtained.3) In situations of considering the horizontal earthquake in plane and arc sliding destruction, the cable axial force formula is derived such as T=Af(kcl)+B by pseudo-static method which shows that cable axial increases linearly with the increase of horizontal seismic effect coefficient.With elastic theory, the paper deduces the anchoring section grout shear stress distribution formula and the location and influencing factors of maximum shear stress appears.The formula shows that the softer the rock is, the greater the shear stress distribution is and the smaller the peak shear stress is. The conclusion is obtained that under the earthquake anchoring section shear stress peak position remains unchanged while plastic—failure does not occur(zrmax=(?)V1/b, b is a parameter related to diameter, elastic module, and Possion' ratio of anchorage section).The smaller the rock Poisson's ratio is and the greater the ratio of rock's and anchoring section's elastic modulus is, the more shallow the anchoring section peak shear stress position is.4) By using the theoretical calculation and the numerical analysis method to analyze the dynamic mechanism and characteristics of anchor structure, the paper gets the dynamic responses of anchor structure and slop which are as follows:①The internal force of anchor structure will increase, it increases by 60% or so in this paper example. The anchor structure plays an important role in reducing the shear strain increment at the toe of slope, limiting slope surface displacement, maintaining the stability of slope. The structure can well coordinate deformation with slope in the earthquake process, fully mobilize their own strength and steady ability of slope masses, and improve the slope masses stress state, which can be helpful to increase shear strength of potential sliding surface and weak structure plane in an earthquake. Compared to the horizontal seismic wave, corresponding vertical wave has little effect on the anchor structure.②On the whole, with the increase of elevation, the amplification factor of horizontal acceleration, velocity, displacement increases. But the PGA amplification coefficient first increases, then decreases upwards along the slope surface.③The vertical earthquakes will increase the shear strain at top of slope and toe of slope, reduce the safety factor of slope, but have little effect on the principal stress, amplification factor and internal force of anchor structure.In this paper, the research contains anchored slope earthquake damage investigation, shear strength parameters of bond interface between anchor structure and rock, dynamic mechanism of interaction between cutting rock slope with prestressed anchor cable structure during strong earthquakes. The research results are helpful to further understanding of the mechanical mechanism of slope with anchor structure during strong earthquakes, and can provide theoretical references for practical projects.