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Although disintegrated dolomite, widely distributed across the globe, has conventionally been a focus of research in underground engineering, the issue of slope stability issues in disintegrated dolomite strata is gaining increasing prominence. This is primarily due to their unique properties, including low strength and loose structure. Current methods for evaluating slope stability, such as basic quality (BQ) and slope stability probability classification (SSPC), do not adequately account for the poor integrity and structural fragmentation characteristic of disintegrated dolomite. To address this challenge, an analysis of the applicability of the limit equilibrium method (LEM), BQ, and SSPC methods was conducted on eight disintegrated dolomite slopes located in Baoshan, Southwest China. However, conflicting results were obtained. Therefore, this paper introduces a novel method, SMRDDS, to provide rapid and accurate assessment of disintegrated dolomite slope stability. This method incorporates parameters such as disintegrated grade, joint state, groundwater conditions, and excavation methods. The findings reveal that six slopes exhibit stability, while two are considered partially unstable. Notably, the proposed method demonstrates a closer match with the actual conditions and is more time-efficient compared with the BQ and SSPC methods. However, due to the limited research on disintegrated dolomite slopes, the results of the SMRDDS method tend to be conservative as a safety precaution. In conclusion, the SMRDDS method can quickly evaluate the current situation of disintegrated dolomite slopes in the field. This contributes significantly to disaster risk reduction for disintegrated dolomite slopes.

Abstract Sandy Dolomite is a kind of widely distributed rock. The uniaxial compressive strength (UCS) of Sandy Dolomite is an important metric in the application in civil engineering, geotechnical engineering, and underground engineering. Direct measurement of UCS is costly, time-consuming, and even infeasible in some cases. To address this problem, we establish an indirect measuring method based on the convolutional neural network (CNN) and regression analysis (RA). The new method is straightforward and effective for UCS prediction, and has significant practical implications. To evaluate the performance of the new method, 158 dolomite samples of different sandification grades are collected for testing their UCS along and near the Yuxi section of the Central Yunnan Water Diversion (CYWD) Project in Yunnan Province, Southwest of China. Two regression equations with high correlation coefficients are established according to the RA results, to predict the UCS of Sandy Dolomites. Moreover, the minimum thickness of Sandy Dolomite was determined by the Schmidt hammer rebound test. Results show that CNN outperforms RA in terms of prediction the precision of Sandy Dolomite UCS. In addition, CNN can effectively deal with uncertainty in test results, making it one of the most effective tools for predicting the UCS of Sandy Dolomite.

Abstract The long-term erosion of rock by solution can induce a series of karst problems. Therefore, this study focused on limestone and conducted dynamic dissolution experiments under deionized water and CO2 solution conditions to study the deterioration mechanism of limestone under nonequilibrium conditions. The results showed that the degree of degradation of the mechanical properties of the samples in a CO2 solution was obviously greater. In a deionized water environment, the degradation of the mechanical properties of the sample is mainly controlled by the physical softening action of the solution. In the CO2 solution environment, the degradation process can be divided into two stages. In the early stage of the experiment (10 days to 20 days), the degradation of mechanical properties of the sample is also controlled by the physical softening action of the solution. With increasing soaking time, the main rock-forming minerals of limestone gradually react with the CO2 solution, the degradation of the sample is controlled mainly by the chemical corrosion of the CO2 solution, and its degradation rate is much greater than that of physical softening. The results can be used as a reference for assessing the long-term stability of underground engineering in limestone karst development areas.

To study the influence of water–rock interactions on the deterioration of rock, particularly the problems of the complex dissolution mechanism of dolomite and the difficulty in establishing chemical damage, dolomite obtained from a tunnel in Yuxi City was utilized. The macroscopic and microscopic dissolution characteristics of dolomite were analyzed using an indoor dissolution test combined with the hydrochemical characteristics of the study area, which were found to be favorable for dissolution. The dissolution of dolomite indicates the chemical decomposition of dolomite crystals, and the crystal failure mode is divided into intergranular dissolved pores and intracrystalline micropore development. Under various pH conditions, as H + is immersed in the rock sample, the failure mode of the rock sample develops from longitudinal cracks to transverse and longitudinal staggered cracks. Based on the aforementioned conclusions, in addition to the principle of chemical kinetics and the generalized Lemaitre strain equivalence principle, a damage model suitable for dolomite chemical erosion was defined. The fitting degree between the calculated value of uniaxial compressive strength and the experimental value reaches 98%, which is of excellent prediction accuracy and reliability. The model for dolomite chemical damage proposed herein provides a theoretical basis for dolomite dissolution damage; the theory of rock chemical damage is thereby enhanced.

Composite foundations have been widely used and promoted in practical engineering applications. However, research on the joint-bearing mechanism of piles and soil within composite foundations is still not comprehensive enough. This paper proposes a method for calculating the additional internal forces of piles and soil within composite foundations. Based on a three-dimensional finite element analysis, this study investigates the variation patterns of the stress, displacement, and additional internal forces of piles and soil in the depth direction under the action of upper loads when using friction piles and end-bearing piles. This research aims to reveal the bearing performance of piles and soil. The results showed that, under the same conditions and due to the presence of end-bearing effects, the internal forces experienced by the entire pile body of the end-bearing piles were more uniform, exhibiting significant advantages in resisting deformation and being able to withstand larger loads. Additionally, the diffusion mechanism of the vertical forces, stresses, and displacements of piles and soil is discussed. Due to the negative frictional resistance of soil and the influence of pile end-bearing effects, the distribution of internal forces and the displacements of piles and soil exhibited different characteristics. This study provides a scientific reference for the theoretical analysis and design of composite foundations.

In China, slope engineering occasionally faces landslides in rocky slopes containing muddy interlayers, primarily triggered by excavation activities. These incidents lead to considerable human casualties and substantial economic losses. However, existing studies predominantly concentrate on the excavation-induced impacts on the stability of rocky slopes characterized by single-layered soft and weak interlayers. Conversely, reports on how excavation influences the stability of bedding cataclastic rock mass high slope containing multimuddy interlayers remain notably absent in the literature. Moreover, unloading due to excavation can swiftly compromise the mechanical integrity and overall quality of the rock mass, consequently impacting the stability of slopes postexcavation. Therefore, this paper modeled the unstable slope excavated at a waste incineration power plant in Yuxi, Yunnan, using the finite element strength reduction method. This approach was employed to comprehensively simulate the entire process of artificial multilevel excavation in a bedding cataclastic rock mass high slope containing multimuddy interlayers. This study investigated the impact of multilevel artificial excavation on slope stability by thoroughly considering factors including alterations in slope morphology, unloading effects, and the degradation of geotechnical parameters. The research yielded the subsequent conclusions. Multimuddy interlayers were the key to the slope’s instability. For slopes subjected to such multilevel excavation, efforts were made to minimize the exposure of muddy interlayers. Slopes above exposed muddy interlayers did not require additional support, while those below needed prioritized reinforcement. The likely instability mode of the actual slope was local destabilization leading to landslides. Furthermore, when using numerical simulation methods to study the impact of excavation disturbances on the stability of such slopes, it was necessary to consider the deterioration of geotechnical parameters to obtain results more reflective of actual conditions. These research findings provided valuable theoretical and empirical support for studies on similar excavated slopes.

Nanhong agate has attracted public attention as the most distinctive gemstone in China. Owing to the limited data on Nanhong agates from a new production area in northeastern Yunnan, this paper presents the first data from gemological studies on these agates. Complex investigations using Fourier-transform infrared (FTIR) spectrometry, ultraviolet–visible (UV–VIS) luminescence spectrometry, Raman spectroscopy, polarizing microscopy, scanning electron microscopy (SEM), electron microprobe (EPMA), and laser ablation–inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses were carried out to obtain basic data concerning the gemological properties, microstructure, and spectroscopic and geochemical characteristics of this interesting material. The results illustrate that Nanhong agates from northeastern Yunnan are mainly composed of α-quartz and also contain certain amounts of moganite, illite, goethite, and hematite. The typical red (yellow) and white appearance can be attributed to the microstructure of the agates, the contents of Fe and Al impurities, and trace elements. The Raman spectra, microstructure, and chemical composition of the unique “yellow-skinned” agates from northeastern Yunnan are significantly different from those of other types of Nanhong agate. This work lays a foundation for the future identification and research of this type of Nanhong agate.

Slope stability prediction research is a complex non-linear system problem. In carrying out slope stability prediction work, it often encounters low accuracy of prediction models and blind data preprocessing. Based on 77 field cases, 5 quantitative indicators are selected to improve the accuracy of prediction models for slope stability. These indicators include slope angle, slope height, internal friction angle, cohesion and unit weight of rock and soil. Potential data aggregation in the prediction of slope stability is analyzed and visualized based on Six-dimension reduction methods, namely principal components analysis (PCA), Kernel PCA, factor analysis (FA), independent component analysis (ICA), non-negative matrix factorization (NMF) and t-SNE (stochastic neighbor embedding). Combined with classic machine learning methods, 7 prediction models for slope stability are established and their reliabilities are examined by random cross validation. Besides, the significance of each indicator in the prediction of slope stability is discussed using the coefficient of variation method. The research results show that dimension reduction is unnecessary for the data processing of prediction models established in this paper of slope stability. Random forest (RF), support vector machine (SVM) and k-nearest neighbour (KNN) achieve the best prediction accuracy, which is higher than 90%. The decision tree (DT) has better accuracy which is 86%. The most important factor influencing slope stability is slope height, while unit weight of rock and soil is the least significant. RF and SVM models have the best accuracy and superiority in slope stability prediction. The results provide a new approach toward slope stability prediction in geotechnical engineering.

The study of hydrogeochemical processes in the karst critical zone (KCZ) is of great significance for the scientific understanding of their internal evolutionary environment and structural characteristics. Karst groundwater is the main information carrier after water-rock interactions. Quantitative analysis of its hydrochemical characteristics and causes is an effective means to reveal the medium environment and hydrodynamic conditions of the aquifer system in the KCZ. In this paper, three typical karst aquifer systems in the KCZ of the central Yunnan Plateau were taken as the research objects. Through field sampling and laboratory testing of karst springs exposed by different aquifer systems, mathematical statistics analysis, hydrochemical diagram, ion ratio coefficient and hydrogeochemical simulation were comprehensively used to deeply analyze the characteristics of hydrochemical components, genesis and aquifer medium of karst groundwater in each aquifer system; the internal relationship and law between the water cycle and hydrochemistry in the key belt were discussed. The results showed that: ①HCO3- and Ca2+ were the highest and most stable ion components in regional karst groundwater, and Mg2+ was the key factor controlling the alienation of hydrochemical types in each aquifer system; ②The rock weathering and mineral dissolution of carbonate rocks were the main causes of the chemical composition characteristics of karst water in each aquifer system, and karst groundwater dissolution on the aquifer of the Huaning aquifer system was still occurring. The alternation of cation adsorption and the weathering and dissolution of silicate rocks were the main sources of Na+ and K+ in regional karst groundwater; ③The development intensity of regional karst, the exposed condition of karst aquifers and the lithology and connectivity of aquifer media jointly shaped the groundwater chemical characteristics of different aquifer systems in the KCZ of the Central Yunnan Plateau.

Crack identification in brittle rocks is a challenging problem in rock mechanics. To represent the details of jointed rock masses, rock-like specimens containing inclined joint sets were generally prepared by three-dimensional (3D) printing using sand. Digital image correlation (DIC) was employed for full-field deformation measurement during loading. The results show that the sand 3D-printed specimen has distinct advantages in the preparation of jointed rock masses. DIC was extended to measure the displacement vector field around newly propagated cracks. Two types of cracks are recognized: tensile and shear cracks. Two different coalescence patterns are classified: step-path failure and planar failure. A covariance matrix-based multivariate measure, the rate of effective variance change (REVC), was proposed to quantify the dispersion of strain data. The variation in the strain dispersion measure was found to be closely related to the crack type. For the first occurrence of tensile and shear cracks, the rates of mutation (RMs) are within the ranges of 1.56–3.42 and 14.54–86.44, respectively, which can be considered a new crack identification criterion. A virtual extensometer method based on DIC was established to interpret the variation mechanism of the REVC associated with different crack types.

In order to have a better understanding of the shear creep characteristics of muddy interlayer in unstable landslides, we took the more “inferior” clay muddy interlayer as the research object, and shear creep experiments under different normal stress levels were carried out by means of hierarchical loading. This paper focuses on the variation law of creep curve and its long-term strength in the clay-type muddy interlayer under different normal stresses. The results showed that the creep characteristics of clay-type muddy interlayer were obvious: at the same normal stress level, instantaneous deformation, initial creep and stable creep appeared at lower shear stress level; at the level of rupture shear stress, there were two cases: the creep curve included three stages of typical initial creep, stable creep and accelerated creep failure, or directly entered the accelerated creep stage until the specimen’s failure. The average shear and stable creep rate of the muddy interlayer specimen increased exponentially with the increase in shear stress. The empirical formula u = u0 + A [1 − e(−Bt)] + Ctn of shear strength could better reflect the creep deformation law of muddy interlayer, and the correlation coefficient R2 varies from 0.90 to 0.99. Based on the definition of long-term ultimate strength, the long-term strength of clay-type muddy interlayer was determined.

To study the corrosion behavior of cement soil in peat soil, the experiment involves the preparation of peat soil by incorporating humic acid into cohesive soil with a lower organic matter content. Cement soil samples are then prepared by adding cement to the mixture. These samples are subjected to immersion in fulvic acid solution and deionized water to simulate different working environments of cement soil. The experiment considers immersion time as the variable factor. It conducts observations of apparent phenomena, ion leaching tests, and unconfined compression strength tests on the cement soil. The experiment results are as follows: (1) With increasing immersion time, the surface of the cement soil in the peat soil environment experiences the disappearance of Ca(OH)2 and calcium aluminate hydrate. Additionally, large amounts of bird dropping crystals precipitate on the surface and within the specimen. The cement soil undergoes localized disintegration due to extensive erosion caused by swelling forces. (2) In the peat soil environment, fulvic acid reacts with the hydration products of cement, resulting in partial leaching of ions such as Ca2+, Mg2+, Al3+, and Fe3+ into the immersion solution. The lower the pH of the fulvic acid immersion (indicating higher concentration), the more significant the ion leaching. Increasing the ratio of humic acid to cement can slow down the leaching of ions. The cement soil undergoes dissolutive erosion in the peat soil environment. (3) The peat soil environment exerts both strengthening and corrosive effects on the cement soil. Cement soil without humic acid exhibits noticeable corrosion in the peat soil environment, gradually decreasing strength as immersion time increases. The strength decreases by 83% from 28 to 365 days. In contrast, cement soil with humic acid experiences an initial period of strengthening, leading to a significant increase in strength in the short term (34% increase from 28 to 90 days). However, the corrosive effects gradually dominate, resulting in a decrease in strength over time. The strength decreases by 80% from 90 to 365 days. This study also explores the strengthening effects of peat soil on cement soil. It identifies phenomena such as extensive erosion and new substance precipitation in cement soil.

AbstractUnusual rainfall is the primary cause of the failure of the tailing dams, and overtopping is the most representative model of the tailing dam failure. The upstream tailing dam was selected as the research object to study the whole process of breach extension and the overtopping dam-failure mechanism under the full-scale rainfall condition. The results showed that the significant size grading phenomenon in the front, middle, and end of the tailing pond was obvious due to the flow separation effect, and its average particle diameter was D50. At different moments of rainfall, the height of the infiltration line at different positions of the dam body was different; at the rainfall of 3600 s, the height of the infiltration line lagged behind the height of the tailing pond, and this phenomenon from the tail of pond to the outside of the dam slope became more obvious. After the rainfall of 3600 s, the height of the infiltration line lagging behind the water level in the pond basically disappeared, and the rate of infiltration line rise kept pace with the rate of water level. The process of overtopping dam-failure experienced dam overtopping (gully erosion), formation of a multistepped small “scarp,” breach rapid expansion, formation of large “scarp,” and burst (fan-shaped formation). The width and depth of the breach showed a positive correlation, and the widening rate of the breach was 3 to 8 times of the deepening rate, especially in the middle of the dam break, widening behavior occupied the dominant factor. The shape of the dam body after failure was parabolic, and the dam body had obvious elevation changes. These results provide the theoretical guidance and engineering application value for improving the theory and early warning model of the upstream tailing dam.

The dolomite rock mass on the slope of the Yanhe domestic waste incineration power plant was used as the research object. The macro- and micro-structural characteristics of intact rock blocks and rock discontinuities were analyzed qualitatively and quantitatively using in-hole television, wave velocity testing, three-dimensional laser scanning techniques, photogrammetry, image processing techniques, and scanning electron microscopy (SEM). The study shows that the degree of fracturing generally decreases with depth over the exposed borehole depth range, and the rock masses are generally very fractured. The wave velocity of dolomite generally increases with the depth of the borehole, and the integrity of the dolomite is either broken or extremely broken. The excavation profile reveals six sets of discontinuities and joints that are straight, smooth, interconnected, and largely unfilled. The angles of the structural bodies of different grain sizes are sharp, with roundness being angular and sharp-angled. The smaller the blocks, the more complex the surface morphology. SEM observations show that the ultramicroscopic fractures are not flat and smooth, and the fractures are folded. Fracturing mainly occurs along intercrystalline and crystal interfaces. These fracture features suggest that the fracturing of dolomite is mainly related to the original sedimentary construction and tectonism.

Reducing the computational workload by simplifying the analysis of karst foundations into a plane strain problem can yield significant advantages. Yet, such an approach fails in reproducing the engineering situation in a rigorous manner. In this regard, this paper proposes an upper-bound method that can effectively analyze the bearing capacity of three-dimensional karst foundations. This method is utilized to investigate the impact of various pile diameters, the ratio of roof thickness to pile diameter, and the ratio of cave width to pile diameter on the stability of karst foundations. The validity of this method is established through an illustrative example. The outcomes illustrate that when subjected to both tensile and compressive horizontal stresses if the maximum horizontal stress surpasses the tensile strength of the rock mass, the roof rock mass may suffer damage. Increasing the ratio of roof thickness to pile diameter can bring down the horizontal stress value. The stability factor is largely influenced by the ratio of roof thickness to pile diameter. The most prominent growth trend of the stability factor is observed when the ratio is less than 3. If the ratio of the roof thickness to pile diameter exceeds 3, the prediction of the bearing capacity estimation for the karst foundation in three-dimensional circumstances is more conservative than that in two-dimensional circumstances.

AbstractThe shape of tailing particles is essential factors of their macroscopic mechanical properties. Scholars have studied the effects of controllable factors, such as loading method, confining pressure, and strain rate, on the strength of tailing sand. However, research on the tailing particle structure and shape through laboratory tests has proved to be difficult due to the uncertain and discrete tailing particle distribution. Thus, the macro-mesoscopic response of heteromorphic tailing particles is rarely investigated. In this paper, the macro-mesoscopic response of heteromorphic tailing particles is studied using multisphere approximation, and numerical simulation of triaxial tests on the particles is conducted. Nonlinear evolution patterns of porosity, internal friction angle, and cohesion of heteromorphic tailing particles with the variation of angularity were investigated using the flexible boundary program developed in this study, which revealed the intrinsic relationship between the mesostructure evolution mechanism and the macroscopic engineering characteristics of heteromorphic tailing particles. The research results showed that (1) changes in angularity led to tailing particle rearrangements and, in turn, porosity changes. With increased angularity and confining pressure, particle sphericity decreased, and the deviatoric and peak stress increased accordingly. In the meantime, the softening was more significant as the peak stress was exceeded, while the cohesive force generally increased. (2) With fixed particle shape and angularity, the internal friction angle decreased slightly as the effective confining pressure increased. (3) In the shearing process, the simulated contact force chain evolution of tailing particles with different shapes was similar. The disordered contact force chains gradually undergo directional connection, i.e., the increased confining pressure reduced the number of free tailing particles and increased the number of stressed particles. (4) The triaxial stress-strain and peak stress in rigid boundary simulations under different confining pressures were slightly lower than those in the flexible boundary simulations. However, the difference was insignificant, indicating the good feasibility and reasonability of rigid boundary simulations for the macroscopic mechanical behaviors in triaxial tests. The research results could offer more direct insights into the macro-mesoscopic response and mechanical mechanisms of nonspherical particles and provide references for the simulation of tailings at the microscopic levels.

Under seismic action, the stock of phosphogypsum (PG) affects the security risk significantly, so it is crucial to study the dynamic characteristics of PG. In this article, unidirectional and bidirectional vibration tests on typical PG in Yunnan under different consolidation-confining pressure and vibration conditions were carried out using a dynamic triaxial apparatus that can be used for bidirectional vibration. The results show that the pore pressure growth of PG under both unidirectional and bidirectional vibrations has obvious stages and can be fitted by the BiDoseResp function. The dynamic strength of PG does not increase monotonically with the increase in consolidation-confining pressure and dynamic stress under the same cyclic stress ratio (CSR) but varies under a specific critical condition. The dynamic strength of PG decreases significantly with the increase in CSR under unidirectional and bidirectional vibrations. The number of vibrations required for liquefaction by bidirectional vibrations is much larger than that by unidirectional vibrations under the same CSR conditions, and the specimens have significant softening characteristics after liquefaction by bidirectional vibrations. The study results can provide theoretical references for studying the dynamic stability of PG reservoirs under seismic action.

Abstract As one of the important influencing factors of tailings dam stability, seepage field distribution within the dam is often affected by the tailings mineral characteristics. While the alkalinity or acidity of reservoir water and long term immersion will partially change the physical and mechanical properties of tailings. This study carried out permeability tests of tailings under the action of chemical solution. On this basis, a three dimensional (3D) model was constructed to analyze the velocity field and effective saturation within the tailings dam. Moreover, the dam section along the valley bottom was selected as the basic section in calculation, so as to analyze the changes in infiltration point and buried depth of the phreatic line under different permeability coefficient ratios. The results suggest that, under the action of acid-alkaline solution, the permeability coefficients of tailings reduced, and the stronger solution acidity-alkalinity resulted in the longer action time and more obvious change; under the action of chemical solution, the fluid flow velocity in the dam gradually decreased, and the drat beach length in the reservoir gradually shortened. Besides, when the upper layer permeability coefficients of tailings was lower than that of the lower layer, the dam phreatic line had a shallow buried depth and a high infiltration point.

In view of the current technical difficulties in the detection of unfavorable geological bodies in karst areas, this paper starts with the fine detection of a borehole wall, near-field of the borehole wall rock and far-field of the borehole wall rock, deeply excavates the correlation characteristics between multi-source borehole data, and proposes detection technology for unfavorable geological bodies in karst development areas based on multi-source borehole data. This is used to establish a multi-source data depth mining model. The correlation characteristics between multi-source data are clarified. The borehole multi-source heterogeneous detection technology is proposed to realize the organic fusion between the detection data of different scales, and effectively estimate the extension range of structural planes and cavities. The joint interpretation method of multi-source drilling data can effectively realize the three-dimensional visualization of unfavorable geological bodies in karst development areas. Through a case analysis, it is shown that this technology is a new and effective exploration method in the engineering geological exploration of karst development areas, and can provide more abundant and reliable exploration data for the fine exploration of geological bodies in the exploration area.

The disposal of peat soil poses an increasingly difficult problem for actual engineering projects of Dianchi Lake area. This study obtains peat soil from seven areas around Dianchi Lake, and the content of humic acid (HA) in peat soil is between 2.36% and 28.13%. Then, this study simulates the peat soil by adding HA into the cohesive soil and uses cement to solidify it. The effect of cement and HA on the strength development of samples is examined by the unconfined compressive strength (UCS) test. Additionally, the microstructures of typical mixes are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). The results showed that HA will significantly reduce the UCS of cement soil. The SEM, XRD, and MIP confirmed that cement hydration reaction increases with cement ratio. In addition to the cementitious soil particles, hydration products gradually fill the pores of the soil and effectively reduce the number of large-size (6000∼40,000 nm) pores in cement soil, which makes the soil particle framework stronger. When the cement ratio increases from 15% to 25%, the diffraction peak of CAH and CSH increases faster. Combined with the results of the UCS test, it could be proved that cement ratio greater than 20% weakens the influence of HA on the strength development of cement soil sample.

The effect and feasibility of peat soil environment (PSE) simulation pose a difficult problem for geotechnical environmental engineering. In this study, the actual content of humic group (HG) in peat soil of Dianchi Lake is determined, and the method of adding humic acid (HA) reagent into cohesive soil and soaking it in fulvic acid (FA) solution is used to simulate PSE of Dianchi Lake. By comparing the HG content of test samples and natural peat soil, the effect and feasibility of simulation test are studied. And the effects of HG on microstructure and material composition of PSE are analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. The test results show that the content of HG and its components of PSE in seven sites of Dianchi Lake are quite different. The simulation method used in this study can simulate the PSE with different HA and FA contents, but the simulation method of soaking samples in FA solution cannot reach the actual effect. The SEM test confirm that the pore size and pore connectivity will increase with the HA reagent. However, FA is wrapped on the skeleton of soil through adsorption and fills some pores, which reduces the pore diameter and weakens pore connectivity. The XRD test shows that both HA and FA can reduce the diffraction peak of main substances in the samples, but not including SiO2. The reason is that HG and cohesive soil particles undergo coordination exchange and ion exchange; free HG combines with cohesive soil particles and transforms into bound HG, forming an organic-inorganic complex PSE.

The large-scale mining of underground mineral resources will lead to the formation of mined-out areas, which will lead to a series of geological and environmental problems. By selecting the Mudengdong village as a case study, this paper uses geodetic satellite remote sensing technologies to perform qualitative analyses and summarize the geological engineering conditions of the factory. Afterwards, the predominant factors that affect the stability of foundation are determined based on the geological survey of karst in goaf structures. Finally, the finite element software ANSYS is used to comprehensively study the karst problem. The results indicate that (1) the karst development pattern in the study area is controlled by the Beiyin mountain fault, in which case the karst in the basin, in the foot slope, or in the pass section is more widespread than in the slope section. Moreover, the karst generally has a vertical form and is in the early karst stage of development; (2) surface rainwater infiltration, earthquakes, and load pressure are the three major factors that affect karst collapse in the study area; (3) by simulating the development of karst caves and the bearing capacity of the karst roof in the goaf structure under different conditions, it is recommended that only civil buildings with not more than three floors can be built in the village. Overburdened soil thicknesses between 6 and 10 m and civil buildings with heights less than 6 m are not suitable parameters for construction activities. If there are hidden soil holes under the overburden layer, dynamic consolidation needs to be applied in order to destroy the structure of the soil layer and to ensure the safety of personnel.

The characteristics of the karst pore structure not only affect the seepage features of the rock mass in the karst area but also have a noticeable effect on the mechanical behavior in the process of rock mass loading. The exploration of the exhibition karst pore structure plays a crucial role in the development of science, technology, and engineering construction. In order to appropriately unlock the problem of image brightness imbalance caused by probe eccentricity in field image acquisition and to realize the proper in situ identification and precise characterization of the borehole structure, the scrutiny of karst pore recognition and a characterization method based on the borehole image are proposed. First, combined with the imaging characteristics of borehole image construction, an eccentric image acquisition model is constructed, the change law of image illumination intensity is clarified, and a suitable pretreatment method is developed for karst pore structures, which effectively enhances the borehole image quality. Subsequently, the pore structure identification method is established by integrating the gradient operator and the maximum interclass variance method, which could successfully screen and filter out the non-porous region segments and ensure that the identified pore structure features are more accurate and rich. Finally, on the basis of representing the single pore structure, number and area proportion functions are constructed in both the depth and azimuth directions, and the distribution characteristics of the pore structure on the borehole wall are evaluated in various dimensions. The achieved results reveal that the proposed pore structure identification and characterization approach could substantially enhance the work efficiency of the karst pore structure in borehole images and provide a simple, reliable, and effective method for the statistics and application of karst pore data.

The bearing capacity of a non-persistent jointed rock mass containing a rock bridge is investigated by combining the lower bound limit analysis theory, a mixed numerical discrete method, and linear mathematical programming. A mixed numerical discrete method is proposed to divide non-persistent jointed rock masses in which rigid block elements are used to simulate the rock blocks, whereas the finite element method is used to simulate the intact rock bridges. A linear mathematical programming model for the ultimate bearing capacity is constructed and solved using the interior point algorithm. The proposed formulation is validated by application to three rock slopes.

Ovarian cancer is one of the five most malignant types of cancer in females, and the only currently effective therapy is surgical resection combined with chemotherapy. Wnt family member 10A (Wnt10a) has previously been identified to serve an oncogenic function in several tumor types, and was revealed to have clinical significance in renal cell carcinoma; however, there is still only limited information regarding the function of Wnt10a in the carcinogenesis of ovarian cancer. The present study identified increased expression levels of Wnt10a in two cell lines, SKOV3 and A2780, using reverse transcription‑polymerase chain reaction. Functional analysis indicated that the viability rate and migratory ability of SKOV3 cells was significantly inhibited following Wnt10a knockdown using short interfering RNA (siRNA) technology. The viability rate of SKOV3 cells decreased by ~60% compared with the control and the migratory ability was only ~30% of that in the control. Furthermore, the expression levels of β‑catenin, transcription factor 4, lymphoid enhancer binding factor 1 and cyclin D1 were significantly downregulated in SKOV3 cells treated with Wnt10a‑siRNA3 or LGK‑974, a specific inhibitor of the canonical Wnt signaling pathway. However, there were no synergistic effects observed between Wnt10a siRNA3 and LGK‑974, which indicated that Wnt10a activated the Wnt/β‑catenin signaling pathway in SKOV3 cells. In addition, using quantitative PCR, Wnt10a was overexpressed in the tumor tissue samples obtained from 86 patients with ovarian cancer when compared with matching paratumoral tissues. Clinicopathological association analysis revealed that Wnt10a was significantly associated with high‑grade (grade III, P=0.031) and late‑stage (T4, P=0.008) ovarian cancer. Furthermore, the estimated 5‑year survival rate was 18.4% for patients with low Wnt10a expression levels (n=38), whereas for patients with high Wnt10a expression (n=48) the rate was 6.3%. The results of the present study suggested that Wnt10a serves an oncogenic role during the carcinogenesis and progression of ovarian cancer via the Wnt/β‑catenin signaling pathway. [ABSTRACT FROM AUTHOR]