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The permeability and porosity of a porous sandstone under cyclic loading–unloading conditions are measured using an integrated permeability and porosity measurement system. Mineral content analysis of the rock is performed. The rock contains open microcracks and pores, which can be closed after cyclic loading–unloading; as a result, the permeability and porosity decrease. Based on the test results, the empirical relations of confining stress-dependent sandstone permeability and porosity are derived. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability of the sandstone under both loading and unloading conditions within the stress range used in the experiment. The permeability of the sandstone is more sensitive to stress than to porosity. It is inferred from the test results that the evolution of sandstone porosity and permeability is related to the relative movement of particles and the closure of microcracks.

Because of the complex geological structure, determination of the field mechanical parameters of the columnar jointed rock mass (CJRM) was a challenging task in the design and construction of the Baihetan hydropower plant. To model the mechanical behaviour of the CJRM, uniaxial compression tests were conducted on artificial CJRM specimens with geological structure similar to that found in the actual CJRM. Based on the test results, the anisotropic deformation and strength were mainly analysed. The empirical correlations of evaluating the field mechanical parameters were derived based on the joint factor approach and the modulus reduction factor method. The findings of the physical model tests were then used to estimate the field moduli and unconfined compressive strengths of the Baihetan CJRM. The results predicted by physical model tests were compared with those obtained from the field tests and the RMR classification system. It is concluded that physical model tests were capable of providing valuable estimations on the field mechanical parameters of the CJRM.

Due to the intensive rainfalls in October 2008 and the heavy snowfalls in February 2009, the Zhenggang deposit exhibited a high probability of landslide reactivation. A good understanding in landslide run-out prediction and failure mechanism analysis was thus highly urgent. In this study, the landslide dynamic simulations were performed for studying the run-out prediction and the failure mechanism of the Zhenggang deposit. The impacts of the friction coefficient at sliding surface and the contact damping ratio on landslide run-out were investigated. The potential improvement of the proposed landslide run-out modeling was discussed.

Permeability is an important factor for seepage analysis of rock material, and a key factor in ensuring the safety of underground works. In this study, the permeability evolution of granite gneiss during triaxial creep tests was investigated. In the context of an underground oil storage cavern in China, a series of hydro-mechanical coupling creep tests were conducted on rock cores of granite gneiss at three different pore pressures to reveal the effect of pore pressure on the permeability evolution and to investigate the correlation between the permeability and volumetric strain during the creep process. During the creep tests, the permeability decreases in the initial loading phase. At all deviatoric stress levels, the permeability remains stable in the steady creep stage and increases rapidly in the accelerated creep stage. Based on the test data, the initial permeability, steady permeability and peak permeability at various stress levels are defined. The effect of pore pressure on the permeability is captured by a linear model. In addition, the relationship between permeability and volumetric strain can be described as a process divided into three phases, with different functions in each phase.

The security and stability of accumulation slopes are significant concerns in the field of engineering. In this study, a 3D geological model was established in VISUALBASIC.NET with the use of NURBS surface technology. Rock cores from the virtual drilling and deformation curve of measuring points were comprehensively analyzed to determine the location zone and distribution law of slip faults. 3D cloud maps of monitoring data on clinometer holes were used to identify the deformation and failure mode of the accumulation slope. Analyses show that a significant slip plane exists at a depth of 28.5–29.5 m. The accumulation slope comes from a tractive landslide and is in the stage of creeping deformation. The calculated safety factor indicated that the accumulation slope may be caused by failure as an effect of heavy rains and earthquake, and the early warning research is very important. The data obtained were applied to examine the instability warning indexes, criteria, and thresholds of the accumulation slope. The results achieved dynamic optimization design and information construction based on feedback analysis of various data. These findings can assist in early warnings for disaster management, provide important safeguards to ensure that key support parts are available, and ensure stable engineering operations. The proposed approach can also be used as a valuable reference for other similar projects.

Outwash deposits is a kind of special geological material composed of soil and stone particles. Since the shear behaviors of outwash deposits are mainly dominated by its complicated structure and composition the strength parameters of which are difficult to be determined accurately. In this work, samples of outwash deposits with random structure and composition taking account of the effects of sizes, shapes and distributions of stone blocks were simulated based on the granular discrete element method. The meso-scale parameters of soil and stone particles were first calibrated by comparing numerical predictions with experimental data. Then a series of numerical direct shear tests for the simulated samples were conducted. Results show that the effects of strain hardening of shear stress–displacement curves become increasingly apparent with the increase of stone content. The shear strength of outwash deposits is dominated by the content as well as by the random distribution of stone blocks. There is an approximate linear relationship between the mean value of shear strength and the stone content lying between 30 and 60 $$\%$$ , while a larger fluctuation in shear strength mainly due to the random distribution of stone blocks. Compared with the mean value of shear strength, the maximum fluctuation of internal friction angle reaches up to 4.26 $$^{\circ }$$ while the maximum fluctuation of cohesion approximates up to 1/3 of its mean value. Results also indicate that the improvement of cementation degree between soil particles increases mainly the macro cohesion of outwash deposits but has almost no influence on the macro internal friction angle. And because of a relative higher strength of stone blocks, the shear yield bands of outwash deposits detours significantly around stone blocks and shows numerous local cracks, which frequently accompanies an acute release of strain energy owing to the geometric redistribution of stone blocks. The integration of laboratory investigations and numerical direct shear tests can be an effective approach to determine the statistical mechanic’s parameters of outwash deposits.

The multi-level evaluation system and rock slope stability were analyzed in this study based on extension and systems engineering theory. An appropriate evaluation index system was selected through hierarchical analysis of geological conditions, excavation and supporting measures, and environmental and monitoring layouts. The comprehensive evaluation system was then divided into three layers: index, description, and target layers. The system can be adopted to conduct a thorough and careful investigation of the research object. The technique matter-element extension transform was employed in the extension model to solve the multi-attribute problem and to prevent incompatibility in rock slope stability evaluation. Qualitative and quantitative grade evaluations were performed by calculating the matter-element dependency degree. The model was then applied to a large-scale rock slope project, and its evaluation criteria for rock slope stability were established. Results were verified through quantitative method of 3D limit equilibrium and qualitative method of 3D nephrogram displacement variation. Results show that extension theory can be utilized to solve problems in rock slope safety.

The Wudongde Reservoir, now being constructed on the lower reaches of the Jinsha River, will be the forth largest hydropower plant in terms of capacity in China. This project includes a concrete arch dam and two large-span underground caverns in both abutments. For their design and construction, in situ stress measurements and geological survey were conducted. In this study, following an introduction of the geological conditions and topography, an interpretation on the test results of in situ stresses is presented for clarifying the distribution features of natural stresses in the engineering area. It is interesting to find that the vertical stress is predominant in the project area and that the horizontal stress reduces largely in the relaxation zone near the bank slopes, while concentrates at the valley bottom and becomes normal in the depth of both abutments. Also analyzed are the effects of valley topography, geological conditions in the project area as well as the macro-regional tectonics on the distribution of in situ stresses at the dam site. A noteworthy finding is that topography and thickness of overburden are the main factors for the intermediate–low stress levels, that regional tectonics governs the stress orientation at the regional scale, and that river erosion, caprock structure and karstic processes have also contributed to the evolution of the valley and in situ stress state.

An automated system, TRAKCELL, was developed for the quantitation of cells in culture. It enabled cell counting, classification according to morphological cell characteristics and measurement of cell proliferation and differentiation. The system was tested on the toxic effect of ascorbic acid on rat brain catecholaminergic neurons in primary culture. In parallel, the effects of nerve growth factor, dexamethasone and forskolin on cell differentiation were studied using rat pheochromocytoma PC12 cells. The results show that the system permits rapid and reproducible measurements of cell density and of the morphological changes observed following various drug treatments.