Wyniki wyszukiwania - Biblioteka Nauki

1

Shear rupture behaviors of intact and granulated Wombeyan marble with the flat-jointed model

100%

Li K. , Han D. , Fan X. , Yang Y. , Wang F.

Archives of Civil and Mechanical Engineering

|

2022

|

tom Vol. 22, no. 1

art. no. e51, 2022

EN

Many large hydropower projects have been constructed in the highly interlocked and non-persistently jointed rock mass (e.g., the columnar jointed basalt). Regarding the granulated Wombeyan marble as an analog of such rock mass, a series of direct shear test simulations under constant normal loading (CNL) and constant normal stiffness (CNS) boundary conditions were performed to better understand its shear rupture behavior using the flat-jointed model based on the discrete element method. The results show that the shear process under the CNS condition can be divided into four stages: linear-elastic stage, yielding stage, shear wear stage and shear sliding stage. The strain-strengthening in the shear wear stage is evident due to the feedback normal stress provided by the cap induced by shear dilation. As the initial applied normal stress increases, the peak shear strength point of specimens under CNL approaches the yield point of specimens under CNS. Additionally, the shear rupture process under CNS is strain controlled in granulated specimens but stress controlled in intact specimens. Correspondingly, the shear rupture zone creation in granulated specimens is not but that in intact specimens is dependent on the initial applied normal stress. Finally, it is demonstrated that the CNS condition can improve the stability of rock slopes or underground excavations embedded in such rock mass and its improvement effect increases with the normal stiffness.

2

Mechanical and fracture characteristics of single tunnel under the induced effect of a key joint

100%

Wang F. , Zhang P. , Li K. , Wang C. , Cui P.

Archives of Civil and Mechanical Engineering

|

2023

|

tom Vol. 23, no. 3

art. no. e206, 2023

EN

The existence of joint at key position will change the stress distribution law around the tunnel, thereby changing the strength and stability of the tunnel. Therefore, a series of uniaxial compression tests were performed on the single-holed samples containing a joint to explore the effect of key joint parameters, including joint inclination (0°, 30°, 45°, 60°, and 90°) and length (20, 30, 40, and 50 mm), on the mechanical and fracture characteristics of the tunnel. Meantime, the DIC equipment and box dimension method were used to analyze the surface strain field of the sample and quantitatively characterize the surface crack of the failed sample, respectively. The experimental results show the uniaxial compressive strength of samples reaches the maximum and minimum values at joint inclination angles of 0° and 60°, respectively, and the strength of samples is negatively correlated with the joint length. Interestingly, the existence of some key joints can help to improve the strength of the single-holed sample. The strain bands and cracks mainly develop around the joint and the tunnel, which is well explained by the stress distribution results calculated by COMSOL software. The numerical results show that with the increase of joint inclination, the tensile stress at the upper endpoint of circular hole is increasing, and the compressive stress at left and right endpoints of the hole slightly increases. Analyzing the relative positional relationship between the coalescence path and the tunnel, the failure modes of the sample with different joint inclinations are classified into three types: center-symmetric failure (0° and 90°), through-joint failure (30° and 45°) and axisymmetric failure (60°). Additionally, the box fractal dimension of the surface crack of failed sample at the peak stress is closely related to the failure mode of the sample, and the box fractal dimension of samples with the same failure mode is positively correlated with their peak stress.

3

Własność złóż kopalin a kryterium społeczno-gospodarczego przeznaczenia gruntu w prawie polskim

80%

Kowal D.

Przegląd Geologiczny

|

2022

|

tom Vol. 70, nr 10

770--779

EN

The regulation of the ownership of mineral deposits by the legislator in Art. 10 of the Geological and Mining Law Act does not clearly indicate when a mineral deposit may be taken over the ownership of the land. The answer is to be found in Art. 143 of the Civil Code and the general clause contained in it, the criterion of socio-economic purpose of the land property. It determines the boundaries of the land property and the scope of permitted interference by the owner into the land. At the same time, this clause is ambiguous and not defined by law. This solution, although it raises some controversy, leaves some flexibility in its application in practice, although it means that the burden of interpreting the above-mentioned general clause has been shifted to the legal doctrine and case law of the courts. On the other hand, its definition allows for the identification of a mineral deposit that may be owned by the owner of the latter. The analysis of the available literature and jurisprudence allows for the emergence of certain trendsin this matter. The theses remain valid: the recognition of opencast mining as constituent parts of real estate and the opposite thesis that this interpretation cannot be applied automatically and indiscriminately. Above all, the thesis of the Supreme Court stands out against the background of the others, which indicates the designations of the criterion of the socio-economic use of land. It gives a full answer, indicating that the delimitation of the real estate boundaries taking into account the above-mentioned criterion should be made each time for a specific real estate, taking into account its location, destination in the localplan orthestudy and the way in which the owner intends to use it in accordance with the law (judgment V CSK 200/14).