Analysis Of Excavation And Support Of High Rock Slope

High rock slope (HRS) is a common type in practiced projects such as mining engineering,communications & transport engineering,hydraulic engineering and national defence construction etc. Its stability has an important influence on those engineering. Instability of slopes due to natural action and human activity has resulted in huge loss,whereas reasonable design and support of slopes evidently benefit people. Therefore,the stability of rock slope has become an important problem so that many studies have been proceeding and occupied many resource provided by nation and local government.On the given engineering background,some problems related to slope stability were thoroughly studied in this dissertation. Some results have been shown as follows:1 . Some main factors to rock slope stability were analyzed by sensibility analysis. The conclusions are shown that earthquake has a most influence on its stability,cohesion c and friction angle in the next one,groundwater level h in the third,and density P of rock masses and height H of slope minimal.2. Reliability of rock slope was done using Responding Surface Method (RSM) and Monte-Carlo Method (MCM) respectively. Reliability index 0 calculated by RSM and MCM are different,which indicates the non-convexity of limit state curved surface in representation of stability of slope. Analysis results in light of MCM indicate that the variation coefficients of c and have more notable influence on P than their means,and their correlation has little.3. Initial ground stresses of rock slope were simulated,using boundary displacement method (BDM) and stress function method (SFM) respectively,and combining with finite element method (FEM). The practical results indicate both methods can simulate the initial stress field with good effect. On the base of least squares,using measured data and some optimization methods,both BDM and SFM can get the simulation of stress field and directly provide initial stress state for subsequent stability analysis of slope. BDM can overcome the shortcoming of excessassumption resultiag from other simulation methods,and be widely used in elastic-plastic model.4. Long-time in-situ supervision of a high rock slope was done. The supervised results show good stability of the slope. Analysis of supervised data of multi-displacement-monitoring instrument (MDMI) showed that displacement of slope has intimate relation with free air temperature but the former lag behind the other.5. Many cases of excavation and support of high rock slopes were symtematically analyzed,and some conclusions were drawn. There exists stress concentration in grading angle induced by excavation and obvious change of stress and strain on sloping surface,which reduce as the increase of distance to surface. Initial stresseshave important influence on excavation and support. Rebounding displacement of slope and axial force of anchor bars increases as the increment ofThe included angle of the rebounding displacement vector and X positive axis will reduce as the increment of horizontal tectonic stresses. The reduction of lithologic characters and weak interplayer have unfavorable influence on stability. This dissertation also analyzed the problem of casually cutting grading angle,which fluently happens in construction of slope engineering.6. This dissertation got the shear strength of sliding surface of slope by backanalysis based on limit equilibrium method. The practical results show that this technique has good effect. According to equilibrium equations,geometric equations and constitutive equations,theoretical derivation of identifiability of back analysis was done when slope is in elastic state.