Sliding surface searching method for slopes containing a potential weak structural surface

Weak structural surface is one of the key factors controlling the stability of slopes. The stability of rock slopes is in general concerned with set of discontinuities. However, in soft rocks, failure can occur along surfaces approaching to a circular failure surface. To better understand the position of potential sliding surface, a new method called simplex-finite stochastic tracking method is proposed. This method basically divides sliding surface into two parts： one is described by smooth curve obtained by random searching, the other one is po｜yline formed by the weak structural surface. Single or multiple sliding surfaces can be considered, and consequently several types of combined sliding surfaces can be simu- lated. The paper will adopt the arc-polyline to simulate potential sliding surface and analyze the searching process of sliding surface. Accordingly, software for slope stability analysis using this method was developed and applied in real cases. The results show that, using simplex-finite stochastic tracking method, it is possible to locate the position of a potential sliding surface in the slope.

The acid dissolution characteristics of cadmium fixed by a novel Ca-Fe-Si composite material

Ca-Fe-Si material(CIS),a novel composite material rich in calcium,iron,manganese and silicon showed marvelous immobilization properties for heavy metal(loid)s in soils.To elucidate the acid stability of Cd fixed by CIS(CIS-Cd)and the underlying immobilizationmechanisms,the acid dissolution characteristics of CIS-Cdwere investigated by using acid titration method and X-ray diffraction(XRD)technique.The results showed that CIS-Cd had distinctive acid buffering capacity in different pH ranges.Based on the titration curve between dissolution rate of CIS-Cd and pH,CIS-Cd can be divided into non acid-stable Cd(9.4%),moderately acid-stable Cd(22.5%)and acid-stable Cd(68.1%).XRD analysis of CIS-Cd at different pH intervals and the correlation curves of dissolution rates of Cd and concomitant elements indicated that non acid-stable Cdwas mainly bound by carbonate,silicate and sulfate(CdCO_(3),Cd_(2)SiO_(4) and CdSO_(4))or co-precipitated with the corresponding calcium salts.Moderately acid-stable Cd was mainly bound by magnesium-aluminum-silicon containing minerals or electrically bound bymanganese iron minerals.Acid-stable Cd remaining undissolved at pH<2.42 included CdFe_(2)O_(4) and ferromanganese minerals strongly bound Cd.It was by multilateral fixation mechanisms that Ca-Fe-Si material possessed marvelous immobilization capability for Cd and strong resilience to environmental acidification as well.The findings implicated that proper combination of calcium-iron-silicon containing minerals could develop novel promising amendments with high efficiency in heavy metal(loid)s immobilization and strong resilience to environmental change.