It is a common type of tunnel under-cross the roadbed slope with weak inter-layer. Rainfall infiltration will cause soil softening, matric suction and strength reduction, which seriously threaten the safety of slope and tunnel. This paper presents a case where a tunnel underlying the roadbed slope with weak inter-layer in Guiyang 1# line, China. The seepage calculation model in MIDAS GTS/NX software, considering hydraulic permeability coefficient characteristic curve and soil-water characteristic curve, was used to analyze the stress and deformation of the roadbed slope and tunnel. The results reveal that rainfall infiltration has great influence on the deformation of roadbed slope with weak inter-layer and the force of internal tunnel. Slope displacement increases rapidly in the early stage and decreases in the late stage, but the absolute value of displacement increases continuously and the slope safety factor decreases gradually, which makes the slope in a dangerous state. The force of tunnel lining increases in the early stage and decreases with the recovery of soil strength after rainfall. The control effects of anchor cable and anti-slide pile reinforcement on slope sliding and tunnel stress were studied. And the anchor cable reinforcement measure is more effective on reducing slope slip and tunnel lining structure internal force.

According to the on‐site vibration velocity monitoring and peak vibration velocity prediction, it is found that the maximum vibration velocity generated by the existing Dizong blasting scheme does not meet the requirements of the maximum allowable vibration velocity of houses. Therefore, the existing blasting scheme is optimized by reducing the maximum single‐segment charge and a variety of damping measures such as multistage duplex wedge groove, adding damping hole, and millisecond blasting. In addition, the blasting data before and after optimization are analyzed and compared by wavelet (packet) technology. The results show that the optimized blasting main frequency domain is increased to 50∼150 Hz and the maximum vibration intensity value is reduced by 79.8%. Based on the time‐energy analysis, the maximum energy value is reduced by 67.75% compared with the original scheme, and the dominant energy of the original scheme is reduced by 97.81%, 71.49%, 82.44%, 95.93%, and 93.03%, respectively, after optimization. The maximum vibration velocity generated by the optimized blasting scheme construction is 1.12 cm/s, which is less than the maximum allowable vibration velocity of the building of 1.2 cm/s, which meets the maximum allowable vibration velocity requirements of the building. The optimized blasting scheme realizes the safe and rapid construction of the two steps of the Dizong tunnel, which can provide a reference for similar engineering construction in the future.

The soil-water characteristic curve (SWCC) is the basis for describing seepage, strength, and constitutive model of unsaturated soil. The existing SWCC models do not work accurately for evaluating loess, because they do not consider the pore deformation that is induced by wetting. The present study develops a new SWCC model for unsaturated loess. The model considers the effect of wetting-induced pore deformation (WIPD) on the SWCC. The new model includes 6 parameters, which could be confirmed by laboratory tests. The pore volume function (PVF) was described by the WIPD. The shift factor ξ1i and the compression factor ξ2i were introduced into the model. The relationship between the void ratio e and ξ1i and ξ2i was established using the average pore radius. The new SWCC model for saturated loess was improved based on the classical van Genuchten (V-G) model. If the WIPD had not been considered, the new model would regress into the classical V-G model. SWCC tests of unsaturated loess with different void ratios were carried out to verify the new model. The model parameters were calibrated in the original state, and the SWCCs of different void ratios were predicted by the new model and found to be in good agreement with the test results.

With the rise of the fourth industrial revolution, traditional methods of analyzing investment have been transformed into intelligent methods under big data and the Internet of Things. This has created a new approach to solving practical engineering problems. This paper examines the formation and evolution of the application of inversion theory in tunnel and underground engineering, summarizing research progress using traditional and intelligent inversion analysis methods to identify three types of target unknown quantities in tunnels and underground projects: initial ground stress, support structure load, and tunnel characteristic parameters. It also offers an outlook on how to optimize inversion analysis methods to solve more challenging and complex tunneling problems in the context of informatization, digitalization, and intelligence. In the current research process of tunnel and underground space engineering problems, the inversion theory system has been improved, but inversion analysis methods still face many challenges. These include the low reliability of initial ground stress inversion under complex geological conditions, the lack of indicators to objectively evaluate the accuracy of inversion analysis, and the high costs of intelligent inversion analysis means. Moving forward in the context of big data and the information era, the future development direction for inversion theory and inversion methods in tunnel and underground space engineering is to combine new monitoring technology, computer vision technology, and simulation analysis technology to establish multifaceted intelligent inversion analysis models.