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A novel, metal-free bromo-thiolation of internal alkynes with hydrobromic acid and disulfides has been developed. The reaction is promoted by commercial-grade nitric acid and is used to construct a series of unexplored β-bromoalkenyl sulfides in moderate to good yield. Most products were obtained with high stereoselectivity as syn-configured tetrasubstituted alkenes. Both sulfide groups of the disulfide reagent were used in this method.

Geotechnical engineering involves various types of uncertainties, as it always deals with highly variable natural materials. Reliability-based design/analysis can play at least a complementary role in the design approach. In this paper, reliability analysis of anti-sliding of retaining wall with the parameters treated as random variables is performed based on the concept of random fields. Both friction angle and cohesion of soils near the interface along the base of retaining wall are treated as Gaussian fields. The spatial correlation and cross correlation of the variables are calculated by a specific covariance function and the seismic loads act on retaining walls are also taken into account. Examples are illustrated to verify the accuracy of the proposed approach. It is found from the numerical results that the spatial correlation of shear strength has an important influence on the probability of the anti-sliding failure of retaining wall. Moreover, the numerical results obtained from the proposed method are in full agreement with those obtained from Monte Carlo simulations. Therefore, the proposed method provides a new view to study the stability of a retaining wall subjected to seismic loads.

Inflatable anchors have been applied to reinforce foundations because soft soil deposits have a low bearing capacity. However, previous research on the mechanical behaviors of inflatable anchors has focused on a single anchor. Since anchors are always used in a group, the uplift behavior of multiple inflatable anchors in soft soil should be investigated. A series of pull-out tests were conducted in this framework by changing the number, spacing, and layout of inflatable anchors. Additionally, the effect coefficient (ECO) of multiple inflatable anchors is discussed. It is found that the failure behavior of multiple inflatable anchors exhibits a three-stage curve: an initial linear stage, followed by nonlinear, and steady-state stages. In addition, the ultimate bearing capacity of multiple inflatable anchors is maximized if the ratio of the spacing of inflatable anchors to the equivalent expanding section diameter of an inflatable anchor is 6.84. It is recognized that the ECO of this new multiple inflatable anchor group is sometimes greater than 1, unlike that of conventional anchors, which have ECOs of less than 1. In addition, the layout of multiple inflatable anchors in the shape of a cinquefoil is recommended due to its high ECO.

It is difficult to forecast the collapse failure of rectangular tunnel roof because mechanical properties of surrounding rocks or soils are strongly affected by uncertainties. A uniform design (UD)-based response surface method (RSM) is proposed to handle uncertainties and to forecast the stability of rectangular tunnel roof with the help of Tunnel Seismic Prediction 203 plus (TSP203PLUS). Firstly, the influence factors of shallow rectangular tunnels are studied by the excavation half-width (Lu), which is derived using Mohr envelope. Since TSP203PLUS is an essential approach to predict the geohazard in tunnels, and a series of parameters such as the density (ρ), P-wave seismic velocity (V) and dynamic Young's Modulus (E) of geomaterials can be read from TSPwin (the software of TSP203PLUS). Then, the relationship among Lu and ρ, V and E are established, so that ρ, V and E read from TSPwin are treated as input variables in the UD-based RSM. Finally, a tunnel located in China is illustrated to demonstrate the efficiency of this approach and the result obtained from the proposed method is validated by Monte Carlo simulations (MCS). The proposed method provides a quick and effective method to study the collapse failure of rectangular tunnel roofs.

Rock-like materials are driven not only by applied stresses, but also by time that exhibits creep characteristics. It is significant to establish three-dimensional long-term strength criterion of rocks. In this paper, it is assumed that there exist three-dimensional penny-shaped microcracks in viscoelastic rock matrix. The mode II and mode III stress intensity factors at tips of three-dimensional penny-shaped microcracks in viscoelastic rock matrix are determined. The orientation angle of micro-failure in rock materials is obtained to describe the creep failure of rocks. The relationship between the micro-failure orientation angle and stress components is derived from the creep fracture criterion. Failure characteristic parameters of penny-shaped microcracks under triaxial creep compressive condition are defined, which are an invariant. A three-dimensional long-term strength criterion of rocks is established using micromechanical method, in which the effects of the intermediate principal stress are taken into account. The proposed three-dimensional long-term strength criterion is novel, and never published before. By comparison with the previous experimental data, it is found that the presented three-dimensional long-term strength criterion is in good agreement with the experimental data.

The selection of experimental data points in response surface methods (RSMs) is still not based on precise guidelines or theory, and multicollinearity—defined as the presence of linear correlations among the uncertain variables—hinders the estimation of the regression coefficients. As a result, a local optimal solution may be obtained. Uniform experimental design (UD) is a quasi Monte Carlo simulations (MCS) method, which has the advantage of coverage of all the experimental points, and is used to analyze the reliability of slopes in this framework. Least absolute shrinkage and selection operator (LASSO) is a regression method that is employed to estimate the regression coefficients. It involves the penalize the absolute size of the regression coefficients so that the coefficients can be estimated even if the variables are multicollinear. In this paper, a new approach is proposed in which a UD-based RSM is combined with LASSO. The response variable, namely, the factor of safety (Fs), is calculated using a 3D rigorous limit equilibrium method (3D RLEM). Two examples are used to demonstrate the validity and capability of the proposed approach. Notably, the probability of failure (Pf) obtained by the UD-based RSM is larger than that for other reliability methods without multicollinearity. Ignoring the influence of multicollinearity may lead to a nonconservative estimation of slope failure probability.

Rocks may exhibit time-dependent behaviors. Long-term strength criterion significantly dominates creep failure of rocks. Rocks contain many microcracks, which lead to degrade of long-term strength. In this paper, it is assumed that there exist three-dimensional penny-shaped microcracks in rocks. The mode II stress intensity factors at tips of three-dimensional penny-shaped microcracks in Burgers viscoelastic rock matrix is derived. A novel micromechanics-based three-dimensional long-term strength criterion is established to consider the effects of time and the intermediate principal stress on creep failure of rocks. By comparison with the previous experimental data, it is found that the novel micromechanics-based three-dimensional long-term strength criterion is in good agreement with the experimental data. This work is licensed under a Creative Commons Attribution 4.0 International License. Copyright Authors are allowed to retain both the copyright and the publishing rights of their articles without restrictions.

A design matrix in response surface method (RSM) that satisfies the orthogonality is very useful because the mean square error can be minimized, so that the response surface is more precise. But the orthogonality of a second-order design matrix in conventional RSM cannot be satisfied. In this paper, a second-order orthogonal experimental design (SOED)-based RSM is proposed by considering the orthogonality of high-order design matrix. The SOED is constructed by changing the length of star points, and the main characteristic of SOED is that the design matrix is diagonal. When the high-order terms are considered in the SOED-based RSM, a globe optimal solution can be found. As the regression equation is determined, the reliability index can be analyzed by the normalized distance between the mean value of the performance function and the critical limit state of the safety factor. A practical large-scale landslide with two slip surfaces is taken to verify the applicability and precision of the proposed method in detail. It is found that the SOED-based response surface is more rigorous than the conventional RSM.

A new route is presented for the selective assembly of isoquinolines and indenes by rhodium-catalyzed tandem cyclization of benzylidenehydrazones with internal alkynes. This method involves the selective cleavage of the N-N bond and the C═N bonds and is dependent on the substituents of the benzylidenehydrazone.

Analysis of the vibration characteristics of slope is the basis of dynamic analysis of slope; therefore, it has an important engineering significance. In this paper, ideal joint rock slope was studied by the modal analysis and harmonic response analysis module in the ANSYS software, meanwhile, the section of the model size and the effects of the structural parameters on the vibration characteristics of slope were also discussed. The results show that the stiffness of the structural surface is the key factors that affect the vibration characteristics of slope, and with the stiffness of structural surface increases, the first modal shape of slope was changed from dislocation vibration that along the structural surface to horizontal vibration. Only the first natural frequency can be excited the "resonance" phenomenon in the horizontal direction under the seismic load. Therefore, the joint slope is more easily to be excited "resonance" under earthquake load because of the first natural frequency of joint slope is smaller than homogeneous slope; moreover, this is consistent to the investigation results of Wenchuan Earthquake.

Based on electromagnetic propagation theory, and used reflected wave detection method of Ground Penetrating Radar. To detect the tunnel with empty areas, void areas, non-dense areas, voids and other defects by the GPR. According to Jianshan Tunnel on-site detection, combined with practical examples to illustrate the GPR as a mean of nondestructive testing. The existence of tunnel defects and their reasons are analyzed comprehensively, and a series of processing measures are proposed.

A novel and general halopalladation/decarboxylation/carbon-carbon forming domino protocol is described for the synthesis of 5-halo-6-substituted benzo[b]naphtho[2,1-d]furans. The protocol represents the first example of trapping the sigma-vinylpalladium intermediate, generated from halopalladation of alkynes, by the decarboxylative coupling reaction.

The presented selective title reaction affords a broad scope of indenes and benzylidenehydrazones in good to high yields.

A mild and general alkylation of terminal alkynes with transient σ-alkylpalladium(II) complexes for assembling alkyl-substituted alkynes is described. This method represents a new way to the use of transient σ-alkylpalladium(II) complexes in organic synthesis through 1,2-carboalkynylation of alkenes.

Various different functionalized alkynes can be methylated through a C(sp)—C(sp3) bond formation process.

A mild and general alkylation of terminal alkynes with transient σ-alkylpalladium(II) complexes for assembling alkyl-substituted alkynes is described. This method represents a new way to the use of transient σ-alkylpalladium(II) complexes in organic synthesis through 1,2-carboalkynylation of alkenes.

A novel palladium-catalyzed methylation protocol for the synthesis of methyl-functionalized internal alkynes has been established. This methylation method is achieved through a C(sp)-C(sp(3)) bond formation process and represents a new synthetic application of sulfonium ylides.

The title reaction provides a new and mild approach to a number of indole products of type (III), (V), and (VII).

A novel, mild, and selective method for the synthesis of the compounds (III), (V), (VI), (VIII), and (IX) is reported.

Ruthenium-catalyzed intramolecular cyclization of an alkyne onto an α-amido C(sp3) carbon atom proceeds smoothly under base-free conditions to give quinolinones (II) and (IV) in moderate yields.

Keeping options open: the new and mild title reaction involving indoles selectively furnishes 1 and 2 with the aid of tert-butyl hydroperoxide (TBHP). The method represents the first example of a copper-catalyzed α arylation of α-amino carbonyl substrates leading to α-aryl α-imino and α-aryl α-oxo carbonyl compounds using a C-H oxidation strategy.

The substitution pattern at the indan products depends on the phosphine ligand in conditions A) or B).

A selective protocol for the synthesis of 2-methylene-3-substituted-2,3-dihydro-1H-inden-1-ones and 2-benzylidene-2,3-dihydro-1H-inden-1-ones has been developed via palladium-catalyzed cyclocarbonylation reactions of arynes with allyl carbonates and carbon monooxide (CO). It is noteworthy that the selectivity of this new route is depended on both substrates and ligands.

Palladium-catalyzed cocyclotrimerization of allenes with arynes has been developed for selectively synthesizing phenanthrenes. In the presence of [(allyl)PdCl] 2 and P(o-tol) 3 , a variety of allenes, including internal and terminal allenes, underwent the cocyclotrimerization with arynes to afford the corresponding phenanthrenes in moderate to good yields. The results showed the selectivity of the reaction based on allenes.

A novel and general halopalladation/decarboxylation/carbon−carbon forming domino protocol is described for the synthesis of 5-halo-6-substituted benzo[b]naphtho[2,1-d]furans. The protocol represents the first example of trapping the σ-vinylpalladium intermediate, generated from halopalladation of alkynes, by the decarboxylative coupling reaction.

Palladium-catalyzed cocyclotrimerization of allenes with arynes has been developed for selectively synthesizing phenanthrenes. In the presence of [(allyl)PdCl] 2 and P(o-tol) 3 , a variety of allenes, including internal and terminal allenes, underwent the cocyclotrimerization with arynes to afford the corresponding phenanthrenes in moderate to good yields. The results showed the selectivity of the reaction based on allenes.

A mild and general cycloaddition of arynes with iodonium ylides protocol has been developed for the synthesis of benzofurans. In the presence of CsF, ortho-silyl aryltriflates were reacted with iodonium ylides smoothly at room temperature in moderate to good yields.

A mild and general cycloaddition of arynes with iodonium ylides protocol has been developed for the synthesis of benzofurans. In the presence of CsF, ortho-silyl aryltriflates were reacted with iodonium ylides smoothly at room temperature in moderate to good yields.

Engineering practices indicate that the soil as foundation has great effect on base vibration. In this paper, Vlasov model is applied to base-foundation (soil) system of dynamic machine. According to the elasticity theory and soil dynamics, the kinetic energy and potential of foundation can be derived. Based on the Hamilton’s variational principle, we are able to establish multivariable fonctionelle equation and Euler’s equations of foundation. Consequently, we can obtain the partial differential equation of free vibration for the foundation on condition that the damping of the system is neglected, which equations are different from the existing references. It is very difficult to solve the complicate differential equations. This paper proposes a new solving method that has great improvement for existing literatures. It provides theoretic basis of the dynamic modeling and dynamic characteristic analysis of bas-foundation system for dynamic machine.

A novel RuCl3-catalyzed intramolecular oxidative hydration–deprotonation–cyclization method was developed for the synthesis of substituted quinolinones. The method serves as the first example of direct carbocyclization of an alkyne with an sp3carbon at the α-position of an amide through an oxidative deprotonation process.