Research On The Design Of Weak Rock Road-Slope

In current rock slope engineering, the slope angle is designed by experience according to different geological condtions of slope. To general weak rock slope, the stability of the slope and the rationality of the design are seldom considered, which results in the irrationality of slope design. In this thesis, according to numerical analysis and field investigation of weak rock slopes, the design method of weak rock slope is established based on statistical analysis and the present design theory is improved. In this thesis, the main researches are as following:1. Through numerical analysis with software UDEC, the deformation properties of slope at different geometrical parameters and mechanical parameters are analyzed. The main influence factors of weak slope angle design are determined.2. Based on numerous field investigations of rock slopes and the statistical analysis of the geometrical parameters of slopes, the rock mass structure, rock mass strength, deformation parameters and other parameters, the current standard analysis model of weak rock slope is obtained. After normalization processing of all parameters, the relation between slope angle and the influence factors is put forward. And the effect weight of each factor to slope angle design is determined.3. Based on numerous wave velocity tests of weak rock mass, the fitting relation between uniaxial compressive strength and wave velocity is established as UCS=0.0154Vp-6.58 and UCS=4.9e0.0008Vp. And the fitting relation between point load strength and wave velocity is established as Vp=1348.7+719.387Is. The relation between wave velocity and rebound strength is approximately linear relationship as R=4.97+0.0068Vp. The result of tests show that it has poor effect to replace uniaxial compressive strength, rebound strength and point load strength with wave velocity, but wave velocity can be used to estimate those index.4. Based on numerical analysis and field investigation, the design equation of weak rock slope angle is established as a=17.391og(γw.Ed)-14.581og(H). And the variation characteristics of slope angle and slope stability after redesign of slope are discussed. 5. Due to current rock quality evaluation method (SMR method) can not be used directly in interbedded slope, the weight of Rebound factor R1 is added in. The rock strength variation extent adjusted factor is put forward and the method of MSMR is obtained. The statistical relation of RMR, SMR, MSMR and slope angle is established as a=50.3ln(RMR)-134,a=393ln(SMR)-80, a=31 ln(MRMR)-52. Based on engineering practice, the feasibility of those relations is verified. Compared with equation 5-4, the character and applicability of those methods are discussed.6. The interbedded weak rock slopes are analyzed with software UDEC. The deformation of toe of slope is selected as evaluation index. The influence rule of rock mass strength variance on slope stability is analyzed. The statistical relation between deformation of toe of slope, slope angle and rock mass strength variance is established.7. Based on extension theory, combining with analytical hierarchy process, the method of weak slope stability evaluation based on extension theory and analytical hierarchy process is put forward. The evaluation method is verified. The stability of the slopes in the database are reevaluated. And the stability of the slopes after redesign based on equation 5-4 are evaluated.8. Through data analysis of field investigation, a database management system of rock slope based on VB and SQL Server 2000 is compiled. The system includes slope query, record adding and deleting of database, statistical analysis, index transforming, slope angle design of weak rock and slope stability analysis.