谈谈降雨对边坡稳定的影响

水是产生边坡失稳的主要因素之一,边坡的失稳大多与水文地质、大气降水有关。根据有关资料,首先论述了边坡失稳与降雨历时、累积降雨量及降雨强度的关系,然后有针对性地分析了降雨对岩石边坡的不利影响,主要是降低岩体强度、抬高地下水位和使边坡内孔隙压力加大。降雨对土质边坡的不利影响有降雨溅蚀、面状侵蚀和沟状侵蚀等。

Stress characteristics of surrounding rocks for inner water exosmosis in high-pressure hydraulic tunnels

Seepage and stress redistribution are the main factors affecting the stability of surrounding rock in high-pressure hydraulic tunnels.In this work,the effects of the seepage field were firstly simplified as a seepage factor acting on the stress field,and the equilibrium equation of high pressure inner water exosmosis was established based on physical theory.Then,the plane strain theory was used to solve the problem of elasticity,and the analytic expression of surrounding rock stress was obtained.On the basis of criterion of Norway,the influences of seepage,pore water pressure and buried depth on the characteristics of the stress distribution of surrounding rocks were studied.The analyses show that the first water-filling plays a decisive role in the stability of the surrounding rock; the influence of seepage on the stress field around the tunnel is the greatest,and the change of the seepage factor is approximately consistent with the logarithm divergence.With the effects of the rock pore water pressure,the circumferential stress shows the exchange between large and small,but the radial stress does not.Increasing the buried depth can enhance the arching effect of the surrounding rock,thus improving the stability.

Responses of wind-induced internal pressure in a two-compartment building with a dominant opening and background porosity Part 2:Parameter analyses and design equations

Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method.Variations of the magnification factors of fluctuating internal pressures were analyzed using 96 model cases under random fluctuating external pressure,and then corresponding design equations were fitted.The results show that the Helmholtz resonance peaks of the admittance functions in both compartments increase with increasing the area of windward or partition wall opening.With increasing the volume of the compartment with an external opening,the resonance peak in this compartment at the higher Helmholtz frequency significantly decreases,at the same time,the resonance peak in the other compartment at the lower Helmholtz frequency also decreases.With increasing the volume of the compartment with background porosity,both resonance peaks in this compartment at the lower and higher Helmholtz frequencies decrease,meanwhile,the resonance peak at the lower Helmholtz frequency for the other compartment also decreases,whereas the resonance peak at the higher Helmholtz frequency increases.Both resonance peaks of the admittance functions in the two compartments decrease with increasing the amplitude of fluctuating external pressure coefficients or reference wind speed.