Study On Influence Of Slope Cutting To Environment

Disaster and its prevention of large engineering activity become the core scientific project of 21th century, the study of which must be based on the sustainable development. Now the construction of railway and highway has been taken precedence over other national construction in west China. But the environment condition restricts the road construction because of complex geology and fragile environment. So the engineering construction, especially the slope excavation, has a large influence on environment Thus, it's practicable to study the slope cutting action.The mountain environmental disaster is the results of coupling of earth's endogenic and exogenic geological process in west China. The slope cutting influences the mountain environment through changing the exogenic system or its environment. The results are that the evolution of mountain environment is accumulated or the mountain disasters are caused.The range of strong disturbed zone due to slope cutting is an important criterion to evaluate the influence degree of slope cutting to environment. The deformation and damage of the cut slope is an accumulation process. After the deformation and damage of slope units accumulates to some magnitude due to stress relaxation, distinct damage of slopes structure will be caused. The deformation modulus is a comprehensive parameter to represent the deformation ability of soil slope. Based on the damage analysis of soil slope, the stress which causes damage variable an abrupt increasing, can be as the criteria to analyze the strong disturbed zone. And the method to analyze the strong disturbed zone is discussed.Different excavation and support sequence have a large effect on the deformation and stability of slope. Based on centrifuge model tests and numerical calculation, (he deformation failure and stress field, due to different excavation and support sequence, are analyzed. The results show that promptly supporting after been cut can reduce the deformation magnitude and improve the stability of slope. The mechanism of promptly support with high stability is that the concentration degree and connection of themaximum shear stress are weak, the stress relaxation are low, and the stress history is better to slope's stability. In contrast, support after the cutting finished cause the cut slope with large stress relaxation and high damage degree.Timely support to cut slope avails to the slope's stability. But to the supper high slopes, the up support measures may fail because of overly stress caused by down stages' excavation. Based on the results of numerical simulation, we suppose temporary support to up stages firstly, and then permanent support after the whole slope been cut. Thus, it can behave the "New Austrian" principle and satisfy the stability with a low cost.Due to fragile environment of mountain area in west China, the slope excavation may not only influence the stability of itself, but also influence the close slope. That is, the close slope may be influenced by the transition of deformation and failure of the cut slope. In the thesis, the transition effect due to part cutting of soil slope is the first time to be studied. The centrifuge model tests of soil slopes with part cutting indicate that three transition types caused because of no support measures taken in time. The first is the whole tensile crack failure under low stability, the second is the arc tensile crack failure under high stability; the third is the shallow collapse failure on the cut face under loose material slope. To engineering practice, we must consider the transition effect for those wreck soil slopes and fragmentary rock slopes, but with little attention to those strong strength soil slopes and integrated rock slopes.The failure of temporary slopes is very common in engineering practice. Rainfall is a key factor to the failure of temporary slopes. The centrifuge model tests indicate that two failure types of soil slope are relevant to different water content, i.e. tensile crack failure occurs under low water content, in contrast, whole failure occurs. There are critical damage variable and the corresponding critical water content, the two failure types of slope can be distinguished by the critical water content.With the increasing of cut degree of slope and support's delay, the evolution of cut slope will behaves self-organization characteristics. That is, the non-linear relation of deformation and slide force acts, and the slope will fail. The forming process of self-organization is the process of reduction of entropy, or the process of deformation's regulary degree from low to high. And the forming process of self-organization is studied trough entropy analysis. Then the disaster prevention measures are presented that timely support measures are taken to prevent the forming of self-organization.