Papers by Author: Ke Qiang He

Abstract: As an exploration and extension of load/unload response ratio theory, unload/ load response ratio theory (ULRR for short) is introduced firstly, and the relationship between ULRR (Y′) and elastic modulus (E for short) is obtained. Based on the basic theory of damage mechanics,the relationship between ULRR and damage variable (D for short) is set up and analyzed with the relationship between E and D. The unloading and loading experiments on a two-story structure carried out in the University of Naples in Italy are introduced;and calculated damage variable is compared with that calculated by Zhang Langping who put forward Weibull distribution as random distribution function. The results show that damage variable of the structure keep highly consistent with calculations of these two methods. Therefore, the relationship between Y′and D provides a new approach to a health assessment to catastrophic failure of large-scale structures and prediction of engineering.

Abstract: A lot of data indicates that rainfall has always played the very important role in landslide triggering. The paper discusses rainfall as a dynamic parameter in term of the load/unload response ratio theory, using the Xintan landslide as a case study. Analysis of the available data indicates that the occurrences of landslides in this region are controlled by rainfall, whose intensity and rainfall processes are the most important dynamic factors in determining the stability of slopes. Therefore, the relationship between rainfall and the movement of typical landslides has been specifically analyzed for the Xintan landslides by using the loading/unloading response ratio parameter of rainfall. The result of this study indicates that the mutation of the loading/unloading response ratio of rainfall of the Xintan landslide in the Three Gorges Reservoir regions, China occurred just before their destabilization, which shows that the loading/unloading response ratio of rainfall and its changing feature can be taken as a precursor for the landslides induced by rainfall.

Abstract: Debris landslide is a widely distributed and its hazard is huge and hard to forecast with traditional method. Instability drivers of the debris landslide and mechanism were systematically analyzed in this paper. And on that basis, the theory of unload-load response ratio was proposed to forecast the landslide's stability. In the view of system dynamics, the unload-load parameter and unload-load response parameter were singled out and the feasibility was able to build up analyzed, and then, the model of unload-load response ratio was built. As an example, the model was used to analyze and calculate the Xintan typical debris landslide. The results were showed. The steady state reflected by the timing curve of the unload-load response ratio was consistent with the landslide's actual status, when Y'→0, the overall unstability of landslide would appear. That showed it was available to use the unload-load response ratio to forecast landslide's deformation stage and as a criterion of landslide instability.

Abstract: In this paper, the probability theory was applied in the stability analysis of a potential landslide, which is located at Lishan Mountain, China. By employing a cyclic loading ring shear apparatus, the geotechnical parameters in the stability analysis was measured under the testing conditions of simulating earthquake and heavy rainfall. Based on the calculation results, the failure probability as well as the stability of Lishan potential landslide was discussed. The results show that Lishan landslide is unstable under cyclic loading and become very dangerous to failure at the time of heavy rainfall.

Abstract: According to the systematic analysis of the composition and destabilized mechanism of debris landslides, this paper have hydro-geological conditions of the landslide and rainfall combined, research the changes of Unload-load response ratio (ULRR), which is considered as the displacement dynamic parameter of debris landslide in the water environment of different roles and conditions. To further explore the stability and its instability law in different stages of the landslide, establish the ULRR-rainfall coupled warning model in order to improve the accuracy of landslide prediction greatly. Meanwhile, based on the example of Xintan, use the ULRR-rainfall coupled warning model to evaluate and predict its stability. The Evaluation and prediction results match the evolution of slope stability. All results above prove that the ULRR- rainfall coupled is a very effective and reliable new method in the forecast prediction of the debris 1andslide．

Abstract: Based on the Drucker-Prager yield criterion which matches with the Mohr-Coulomb yield criterion under the plane strain condition, this paper sets up a cusp catastrophe model of maximum horizontal and vertical displacements to strength reduction factor by using the cusp catastrophe theory. And the catastrophe criterion of slope failure is quantified to the control variable (u) and discriminant (△) which are evaluated by comparing with zero. Taking the above study as the foundation, the cusp catastrophe model is applied to solve one of the standard test ACADS examples. On the two criterions for slope failure of horizontal and vertical displacements catastrophe model, the safety factor of the slope is 0.988 which is consistent with those by ACAS. It shows that the cusp catastrophe model in slope failure analysis is feasible and practical.