Sandy dolomite strata are widely distributed in the diversion tunnel of the Yuxi section of the Water Diversion Project in Central Yunnan (WDPCY). The water-sand inrush is the main failure phenomenon in the construction of sandy dolomite tunnel, which has seriously and commonly threatened the safety of the Chenaju (CNJ) tunnel in the WDPCY. In this paper, we established the discriminant matrix of the water-sand inrush risk assessment by consulting the experts, including the designers and construction personnel of the CNJ tunnel. Then, the risk assessment of water-sand inrush in the CNJ tunnel is carried out based on the proposed Fuzzy-AHP method. The results show that (1) a hierarchical model for risk assessment of water-sand inrush in sandy dolomite tunnel is constructed by criterion and index including thirteen factors. (2) The main criterion layer factors affecting water-sand inrush in the sandy dolomite tunnel are dolomite’s sandy degree and water yield. (3) The risk grade of water-sand inrush in the sections of YX49 + 089∼YX49 + 099 and YX51 + 637∼YX51 + 647 in the CNJ tunnel is V, which indicates very high risk. The assessment results are consistent with the actual engineering situation, which indicate the proposed method can provide the reference for the risk management in a similar project.

Studying the deformation and failure mechanism of the Tanziyan landslide in Yesanguan Town, Badong County, and designing the controlling measures are of great significance to ensure the sustainable development of urban planning and construction. In this paper, stability of Tanziyan landslide is analyzed using the calculation method of complex plane slip surface. After consideration of the essential characteristics of the disaster body,the deformation and failure mechanism of the landslide is studied, and the corresponding landslide treatment measures are presented. Results show stability state of the landslide is understable to unstable as a whole, and the development process can be roughly divided into three stages: sliding, bending and the cracks are connected. Finally, it is proposed to cut and reshape the slope from the crack groove on the slope top to the national highway, and thenlattice beams and anchor cables are presented to protect the reshaped slope surface. Ecological bags are used to stack and regreen between the lattice structures. A retaining wall is built on the inner side of the national highway at the bottom of the slope cutting area, an active protective net is laid on the east side of the crack groove, and monitoring works are set for potential deformation areas. In short, experiences of engineering practice in this landslidecan provide reference for similar projects.

The stability of high rock slopes has become a key engineering geological problem in the construction of important projects in mountainous areas. The original slope stability probability classification (SSPC) system, presented by Hack, has made obvious progress and been widely used in rock slope stability analysis. However, the selection and determination of some evaluation indexes in the original SSPC method are usually subjective, such as intact rock strength and weathering degree. In this study, the SSPC method based on geological data obtained in the prospecting tunnels was presented and applied. According to the field survey and exploration of the prospecting tunnels, the weathering degree of the slope rock mass was evaluated. The empirical equation for the maximum stable height of the slope was applied to the slope stability evaluation in the presented SSPC method. Then, the slope stability probability of numerous cutting slopes in the sandstone unit was evaluated using the presented system. Results of the Geostudio software based on the limited equilibrium analysis of the investigated slopes were compared with the results obtained by the SSPC method. The results indicate that the SSPC method is a useful tool for the stability prediction of high and steep rock slopes.

Excavation damaged zones (EDZs) in deeply buried underground powerhouse have become major obstacles to design and support, which potentially threaten safety and stability and increase construction and support costs. In this study, investigations of the EDZs were performed by applying an acoustic velocity detecting method in Houziyan hydropower project, southwest of China. A total of 38 testing boreholes distributed in high sidewalls of the main powerhouse were carried out, and corresponding 153 curves were obtained and analyzed. Then, EDZs were divided into highly damaged zone (HDZ), slightly damaged zone (SDZ), and excavation influence zone (EIZ), respectively. Furthermore, we classified the wave velocity curves into four categories: type I, type II, type III, and type IV. EDZs were qualitatively assessed based on the curve categories; in addition, we used a qualitative assessment method, which mainly involved an index of damage degree named D. The assessment results show that HDZ, but not SDZ, was significantly asymmetrically distributed in the upstream (average depth of 4.1 m) and downstream (average depth of 7.5 m) high sidewalls; in partial areas, depth of HDZ exceeded the length of designed rock bolts, which indicates that rock bolts cannot restrain crack development and EDZs evolution. Generally, EDZs distribution was consistent with deformation and failure phenomena distribution; compared to the field failure phenomena, the assessment results were reliable and reasonable. Finally, EDZs formation mechanism was discussed, and it can be concluded that the relatively large intermediate principal stresses σ₂ were a critical driving factor of the EDZs evolution.

Analysis of the movement trajectory and risk assessment of the high‐slope dangerous rock mass collapse are of great significance for preventing and controlling the geological disasters of collapse. This study firstly takes the dangerous rock mass of the high slope in Pu’erdu Town, Yanjin County, Zhaotong City, Yunnan Province, as the research object, calculates and analyzes the trajectory of collapse movement of several groups of dangerous rock mass with great threat, and RocFall are used to carry out numerical simulation analysis and verification. Secondly, the risk and vulnerability of the dangerous rock mass in the study area are analyzed, and the risk evaluation is carried out through the risk evaluation matrix to clearly define the risk level. Results show that if the dangerous rock mass collapses, the horizontal movement distance was approximately 53–88 m, and the maximum bounce height of the platform was approximately 3–18 m, which will seriously threaten the life and property safety of residents. There is little difference between the simulation of the collapse of dangerous rock mass by RocFall software and the calculation result of the formula. Although RocFall software is more intuitive and can be directly compared with charts, software cannot completely simulate the actual situation, and it is only suggested as a reference from design rather than a basis of design. The result of risk evaluation shows that there are 2 high‐risk dangerous rocks, 3 medium‐risk dangerous rocks, and 1 low‐risk dangerous rock in this area. It is suggested that a reasonable and scientific engineering treatment scheme should be put forward as soon as possible in combination with the collapse trajectory of the collapsing movement.

Dangerous rock mass in the overhanging slope of Puerdu town has good free‐face condition, high position, and great potential energy, identification and stability evaluation of which is a difficult problem in the disaster prevention. In this paper, the limit equilibrium method was used to evaluate the dangerous rock mass stability in the overhanging slope. Firstly, geomorphic characteristics and the distribution of dangerous rock mass are determined by the field geological survey. Secondly, six dangerous rock masses which may cause more threat are studied, with defining their failure modes and characteristic parameters. Finally, a simplified geological model is established, the stability coefficient of dangerous rock mass under different conditions is calculated by the limit equilibrium method, at the same time, stability analysis of dangerous rock mass is carried out based on the stereographic projection, and the hazard probability is estimated by the empirical formula. Results show that joints obviously developed in the dangerous rock mass of W1, W2, W3, W4, W5, and W6, with falling‐type and toppling‐type failure modes. In the natural condition, the dangerous rock mass is understable and unstable under the rainstorm and earthquake conditions. Consequently, rainstorm and earthquake are the key triggering factors of the instability and collapse of dangerous rock mass.