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Defining the trajectory of hydraulic fractures crossing bedding planes and other fractures is a significant issue in determining the effectiveness of the stimulation. In this work, a damage evolution law is used to describe the initiation and propagation of the fracture. The model couples rock deformation and gas seepage using the finite element method and is validated against classical theoretical analysis. The simulation results define four basic intersection scenarios between the fluid-driven and preexisting fractures: (a) inserting—the hydraulic fracture inserts into a bedding plane and continues to propagate along it; (b) L-shaped crossing—the hydraulic fracture approaches the fracture/bedding plane then branches into the plane without crossing it; (c) T-shaped crossing—the hydraulic fracture approaches the fracture/bedding plane, branches into it, and crosses through it; (d) direct crossing—the hydraulic fracture crosses one or more bedding planes without branching into them. The intersection scenario changes from (a) → (b) → (c) → (d) in specimens with horizontal bedding planes when the stress ratio β ( β = σ y / σ x ) increases from 0.2 to 5. Similarly, the intersection type changes from (d) → (c) → (a) with an increase in the bedding plane angle α (0° → 90°). Stiffness of the bedding planes also exerts a significant influence on the propagation of hydraulic fractures. As the stiffness ratio E 1 ¯ / E 2 ¯ increases from 0.1 to 0.4 and 0.8, the seepage area decreases from 22.2% to 41.8%, and the intersection type changes from a T-shaped crossing to a direct crossing.

The concept model of high-level radioactive waste (HLW) repositories in deep geological media is based on a multi-barrier system. In accordance with this concept for the storage of spent nuclear fuel, the canister with the fuel should be surrounded by bentonite blocks. A useful technique for producing compacted blocks of bentonite is described in this work. These blocks were uniaxially compacted with a mold that yielded blocks with an outer diameter of 1200 mm, inner diameter of 600 mm, and angle of 45 degrees. A technique has been developed for manufacturing blocks from GMZ-Na bentonite using a large press machine. During these tests, blocks were compacted for studying different factors that affect the quality of the blocks. The blocks were also examined with respect to damage and cracks. The results from these tests revealed that the natural water content of the bentonite powder leads to several problems that affect the quality of the blocks. In the subsequent test, the blocks were manufactured with different compaction rates using powders with high water content. Samples (nine cylindrical samples in total) were taken from the two examined blocks, and the water content and the density were determined. The results revealed that the solid block is rather homogenous. This indicates that the technique of compacting bentonite blocks established in the present study is suitable for manufacturing buffer blocks.

The concept model of high-level radioactive waste (HLW) repositories in deep geological media is based on a multi-barrier system. Buffer material is considered as an important artificial engineered barrier between the canister and the surrounding rock. Coupled thermo-hydro-mechanical (THM) phenomenon will occur in the buffer material under conditions of the heat generated by the radioactive decay and of the underground water and geo-stress supplied by the surrounding rock, et al. Therefore, it is considered of fundamental important for the evaluation of long-term behavior that the processes taking place in the near filed for the safety operation of the HLW repository. Following the need of understanding the coupled THM behaviors of bentonite, mock-up test is considered as one of the most effective approach. An experiment at middle scale whose internal diameter is 20 cm and inner length 45 cm is proposed as a complementary step for the China-Mock-up test. The middle one is carried out to obtain the bentonite parameters and to identify the processes by simulating the conditions of the China-Mock-up test. The aims intended are to know and understand the long-term behavior of the bentonite submitted to thermal and hydraulic gradients at the opposite direction. The characteristics of the bentonite related to swelling pressure, relative humidity and temperature are presented and interpreted. The results can provide design parameter and theoretical basis for HLW repository.

The swelling characteristics of bentonite is important to evaluate the long-term performance of deep geological repository of nuclear waste. A series of wetting tests on GMZ sodium and calcium bentonite were performed to investigate the swelling characteristics under different conditions. The influences of initial dry density and particle size were studied at different temperature. The test results show that the swelling deformation due to wetting is mainly affected by the dry density and little affected by particle size. The swelling ratio of GMZ bentonite increases with the increase of initial dry density. However, only the swelling ratio of sodium bentonite increases with the rise of temperature. The process of swelling deformation is a single or multi-stage mode depending on the initial dry density. Finally, the sample of the bentonite is subjected to a rapid swelling with the increase of the initial dry density. The swelling property of sodium bentonite is much higher than that of calcium bentonite. All results are very important for the study of swelling properties of GMZ bentonite.

According to the preliminary concept of the high-level radioactive waste (HLW) repository in China, a large-scale mock-up facility, named China-Mock-Up was constructed in the laboratory of Beijing Research Institute of Uranium Geology (BRIUG). A heater, which simulates a container of radioactive waste, is placed inside the compacted Gaomiaozi (GMZ)-Na-bentonite blocks and pellets. Water inflow through the barrier from its outer surface is used to simulate the intake of groundwater. The numbers of water injection pipes, injection pressure and the insulation layer were determined based on the numerical modeling simulations. The current experimental data of the facility are herein analyzed. The experiment is intended to evaluate the thermo-hydro-mechano-chemical (THMC) processes occurring in the compacted bentonite-buffer during the early stage of HLW disposal and to provide a reliable database for numerical modeling and further investigation of engineered barrier system (EBS), and the design of HLW repository.

Distributed test framework can not only ensure that the quality of software testing but also can improve the automated test efficiency, and so on. The key technologies of the distributed test framework are studies in this paper. First, the main idea of the distributed test framework and its overall structure are given combined with the actual project needs; based on it, the key technologies involved are described in detail; at last, the paper fully improved that distributed test framework truly has the advantage of enhancing the overall test efficiency, saving the cost of human resources and so on, by a clear and simple test case.