The influences of rockfall on human engineering have been increasing in Tibet with the rapid development of the western region of China. This study proposed a multi-approach to carry out rockfall investigation and hazard assessment. As a case study, the rockfall hazard from Nang County to Jiacha County in Tibet was assessed. Firstly, we summarized the characteristics of spatial distributions of typical rockfall sources using Digital Elevation Model (DEM) and unmanned aerial vehicle (UAV) aerial images with resolution of 10 m. According to the thresholds of slope angle, slope aspect and elevation distribution of typical rockfall sources, we obtained all of the rockfall source areas in study area semi-automatically in ArcGIS platform. Secondly, we improved the efficiency and accuracy of detailed field investigation by using a three-dimensional (3D) point cloud model and rock mass structure extraction software. According to the analysis result, the dominant joint set was J1, whose orientation was basically consistent with the Yarlung Tsangpo Fault. The combination of J1, J2 and J4 cut the rock mass into blocks of wedge with J1 as potential sliding planes. It was indicated that the stability of the rock mass in study area was mainly controlled by the characters of joint sets. Finally, we applied the improved reclassification criteria of the Rockfall Hazard Vector (RHV) method in rockfall hazard assessment according to protection capabilities of the current protection facilities, making the result more valuable for geohazards prevention work. Based on this multi-approach, we obtained that 10.92% of the 306 provincial highway and 9.38% of the power line were threatened by potential rockfall hazards in study area. The hazard assessment results of study area were also of certain guiding value to the linear project planning and geohazards prevention work.

Due to the significant advantages of steel-concrete composite beams, they are widely used for accelerated bridge construction (ABC). However, there is still a lack of experimental research on the proper design of ABC, especially in the slip with a different group of shear connectors. As a component of steel-concrete composite structure, shear studs play a vital role in the performance of composite structures. This paper investigates the influence of group studs in simply supported and continuous box girders. To this end, three sets of simply supported steel-concrete composite small box girders and two continuous steel-concrete composite small box girders were made with different groups of shear studs, and the slip generated along the beams was recorded under different caseloads. The results were then compared with the proposed simplified equations. The results show that the slip value of the test beam is inversely proportional to the degree of shear connection. The slip of Simply Supported Prefabricated Beam-3 (SPB3) is 1.247 times more than Simply Supported Prefabricated Beam-1 (SPB1), and 2.023 times more than Simply Supported Prifabricated Beam-2 (SPB2). Also, the slip value of Experimental Continuous Beam-1 (ECB1) is 1.952 times more than Experimental Continuous Beam-2 (ECB2). The higher the degree of shear connection, the smaller the maximum slip value.

With the increasing trend of office buildings towards high-rise, multifunctional, and structurally complex architecture, the difficulty of engineering cost management has increased. Accurately estimating costs during the decision-making stage is crucial for ensuring the overall project’s financial viability. Therefore, finding straightforward and efficient methods for cost estimation is essential. This paper explores the application of algorithm-optimized back propagation neural networks and support vector machines in predicting the costs of office buildings. By employing grey relational analysis and principal component analysis to simplify indicators, six prediction models are developed: BPNN, GA-BPNN, PSO-BPNN, GA-SVM, PSO-SVM, and GSA-SVM models. After considering accuracy, stability, and computation time, the PCA-GSA-SVM model is identified as the most suitable for office building cost prediction. It achieves stable and rapid results, with an average mean square error of 0.024, a squared correlation coefficient of 0.927, and an average percentage error of 5.52% in experiments. Thus, the model proposed in this paper is both practical and reliable, offering valuable insights for decision-making in office building projects.

The rock fall trajectory and its mechanisms are the most difficult to predict, owing to the complexity of the slope and the Irregular shape of falling rocks. To acquire a better knowledge of the rock fall mechanism of platy rock and to investigate the influence of various impact parameters, a comprehensive physical model experimental study was undertaken based on 3D printing technology using a high-speed camera and specially developed block release system. Based on the experimental results, the effects of the slope angle on the stopping position, the instantaneous kinetic energy and collision position of platy rock block were analyzed. Meanwhile, the effects of movement forms of platy rock before and after collision on the normal coefficient of restitution and the tangent coefficient of restitution were discussed. It is observed that rock fall trajectory depends not only on slope material characteristics, slope angle but also on factors related to the platy block (weight, size and shape). The experimental results showed the value of restitution coefficient exceeding 1 has an important relation with the combination of various movement forms (including the flip motion) and the change of movement forms of platy rock before and after the collision. A new feasible experimental method for research and prevention of rock fall disaster was put forward. It would be important and helpful to the geo-hazard control work.

The identification of potential rockfall and the accurate prediction of its trajectory are critical in prevention and mitigation of rockfall hazard. It is an important precondition to assess the uncertainty of rockfall motion, study the effective identification technology of potential rockfall, predict the rockfall trajectory, and calculate the threatened area by rockfall hazards. In this study, field investigations and numerical simulations were carried out to identify potential rockfall on a weathered rock slope. As a case study, our calculations results show that the area of tensile stress concentration and plastic failure is the potential area where the rockmass will fall off the surface of the weathered rock slope. A mathematical model for calculating the rockfall influence area of the weathered rock slope was established based on the optimization theory, neural network technology, and genetic optimization algorithm. The rockfall influence area of the weathered rock slope was determined using maximum horizontal distance of rockfall in the specified slope cross sections and described on the topographic map using spline curves to form a closed possibly vulnerable area. As a case study, our calculations confirm that the distributions of the plastic failure and tensile stress areas obtained from the numerical simulations are consistent with the dangerous rock masses identified by field investigations at Guanyindong Slope that is a popular tourist scenic spot in Zhejiang Province, China. In this study, it has been indicated that the influence area can be used as the basis for the design of passive protection methods for rock slopes vulnerable to rockfall hazards.

Deep rock masses have long been in a complex geomechanical environment characterized by "high ground stress, high groundwater pressure, high temperature, and strong disturbance", which complicates their structural characteristics and mechanical behaviors. The − 850m roadway in Qujiang Coal Mine is laid longitudinally under the 805 working face and coal pillars. Affected by the mining activities of the upper working face and the eccentric pressure of coal pillars, the roadway exhibits various deformation and failure characteristics. In this study, field investigations, stress monitoring of bolts and cables, and surrounding rock deformation monitoring were conducted to analyze the deformation and failure patterns of the mining-induced dynamic pressure roadway. Additionally, the FLAC3D numerical software was used to verify and analyze the proposed support countermeasures. The results show that: (1) Through methods such as axial force monitoring of bolts and cables and surrounding rock deformation monitoring, it is found that the − 850m mining-induced dynamic pressure roadway has obvious zonal failure characteristics, which are divided into the rear continuous (high-pressure) deformation zone and the front disturbed (dynamic pressure) deformation zone. (2) In the front disturbed (dynamic pressure) deformation zone, failures mainly occur in the roadway roof, mostly in the form of sliding shear failure. In the rear continuous (high-pressure) deformation zone, failures are mainly concentrated in the floor and arch feet: the floor is prone to plastic extrusion deformation and failure, while the arch feet mainly suffer from punching shear and inward folding failures. (3) Based on the failure patterns of different zones in the − 850m roadway, it is proposed that the "triple-anchor" combined support technology should be applied in the rear continuous (high-pressure) deformation zone, and the support concept of combining resistance and yielding should be adopted in the front disturbed (dynamic pressure) deformation zone. (4) FLAC3D numerical simulation was carried out, and the simulation data were consistent with the field measured data of reinforcement, confirming the rationality and effectiveness of the proposed zonal support countermeasures. The research results provide a certain reference for the surrounding rock deformation control of deep mining-induced dynamic pressure roadways in the future.