Self-consolidating concrete (SCC) is a well-known type of concrete, which has been employed in different structural applications due to providing desirable properties. Different studies have been performed to obtain a sustainable mix design and enhance the fresh properties of SCC. In this study, an adaptive neuro-fuzzy inference system (ANFIS) algorithm is developed to predict the superplasticizer (SP) demand and select the most significant parameter of the fresh properties of optimum mix design. For this purpose, a comprehensive database consisting of verified test results of SCC incorporating cement replacement powders including pumice, slag, and fly ash (FA) has been employed. In this regard, at first, fresh properties tests including the J-ring, V-funnel, U-box, and different time interval slump values were considered to collect the datasets. At the second stage, five models of ANFIS were adjusted and the most precise method for predicting the SP demand was identified. The correlation coefficient (R²), Pearson’s correlation coefficient (r), Nash–Sutcliffe efficiency (NSE), root mean square error (RMSE), mean absolute error (MAE), and Wilmot’s index of agreement (WI) were used as the measures of precision. Later, the most effective parameters on the prediction of SP demand were evaluated by the developed ANFIS. Based on the analytical results, the employed algorithm was successfully able to predict the SP demand of SCC with high accuracy. Finally, it was deduced that the V-funnel test is the most reliable method for estimating the SP demand value and a significant parameter for SCC mix design as it led to the lowest training root mean square error (RMSE) compared to other non-destructive testing methods.

Large deformations in local areas during service in a mine roadway are prone to roofing hazards, seriously threatening people’s lives and urgently needing to be addressed by means of support optimization. Traditional methods of studying the stability of the roadway roof are mainly based on the theory of the surrounding rock loosening circle, but few studies analyze the stability of roadway roofs around the failure distribution and expansion of weak interlayers. Therefore, the relationship between the deformation characteristics of the tunnel envelope and the thickness of the soft and weak interlayer and the underlying hard rock layer was investigated using a comprehensive research method such as theoretical analysis, numerical simulation, and field monitoring. The results show that the form of roadway roof failure is determined by weak interlayer thickness. For a mining-disturbed roadway, if the weak interlayer thickness remains unchanged, as the underlying hard strata thickness increases, the existence of a more integral hard stratum cannot prevent plastic zones from forming in the weak interlayer but can prevent them from developing in the key layer 1. If the underlying hard strata thickness remains unchanged, the smaller the weak interlayer thickness, the smaller the area of plastic zone failure in the roadway roof. After the deformation characteristics of the roadway containing the weak interlayer were clarified, according to its characteristics, the support optimization method of increasing the length of anchor bolt and anchor cable is proposed. The displacement of the roadway roof was reduced by 35% after verification by numerical simulation. After applying the support optimization method on site, the roadway displacement basically stabilized after 40 days, with the roof slab sinkage, two gang convergence and bottom bulge reaching 53 mm, 42 mm and 39 mm, respectively. The overall deformation of the roadway was small, effectively controlling the surrounding rock deformation and reducing economic losses for the mine.

Assuming that relative sliding does not occur to the coordinated deformation of bolt/cable and surrounding rock, a constitutive model of coupling effect between bolt/cable and creep surrounding rock is established to study the variation law of anchorage force on surrounding rock with time increasing, the parameters of physical-mechanics of bolt/cable and the mechanical parameters of surrounding rocks analyzed, and the sensitivity of the above parameters to anchorage force compared using sensitivity analysis method. Results show that the validity and effectiveness of the proposed constitutive model is verified by numerical simulation. And the main factors affecting the anchorage force for creep rock are diameter (D), elastic modulus (E ^c), and initial pre-stress force (F) of bolt/cable, viscoelastic modulus (E ^R), viscoelastic coefficient (η ^R) and initial in situ stress (σ ₀) of surrounding rocks, respectively. For bolt or cable, increasing the parameter values of D, E ^c and F can strengthen the anchorage force; while for surrounding rocks, large value of σ ₀ and small value of η ^R are beneficial to the exertion of anchorage force. The sensitivities of these factors from high to low are D, E ^R, σ ₀, E ^c, F, η ^R, respectively. The result can provide some guidance for the formulation of on-site support scheme and parameters selection.

The research on the influence of radial stress on the mechanical properties of an anchorage structure has important theoretical and practical significance for optimizing the design of anchorage structures and saving support cost. Firstly, based on the phenomenon of concrete splitting found in the laboratory model test, the influence of radial stress on the mechanical properties of an anchorage structure is analyzed. Secondly, using the criterion of maximum tensile stress and the Mohr–Coulomb criterion, the influence of radial stress on the mechanical properties of rock around the borehole is analyzed. Finally, the influence of radial stress on the shear stress at interface and the ultimate bearing capacity of the anchorage structure is studied by numerical simulation. The results show that the existence of radial stress in the anchorage section greatly improves the bearing capacity of the anchorage structure. With the increase of confining pressure, the maximum value of interfacial shear stress increases obviously. The larger the confining pressure is, the faster the convergence speed of the finite element method (FEM) program is, which shows that the mechanical properties of the anchorage structure are improved obviously. With the increasing confining pressure, the adaptability of the anchorage structure to deformation is stronger and the anchorage structure is less likely to fail. The ultimate bearing capacity of the anchorage structure increases linearly with the increase of confining pressure, and the effect of confining pressure on the ultimate bearing capacity is very significant.