Method for evaluation of geological strength index of carbonate cliff rocks:Coupled hyperspectral-digital borehole image technique

The deterioration of unstable rock mass raised interest in evaluating rock mass quality.However,the traditional evaluation method for the geological strength index(GSI)primarily emphasizes the rock structure and characteristics of discontinuities.It ignores the influence of mineral composition and shows a deficiency in assessing the integrity coefficient.In this context,hyperspectral imaging and digital panoramic borehole camera technologies are applied to analyze the mineral content and integrity of rock mass.Based on the carbonate mineral content and fissure area ratio,the strength reduction factor and integrity coefficient are calculated to improve the GSI evaluation method.According to the results of mineral classification and fissure identification,the strength reduction factor and integrity coefficient increase with the depth of rock mass.The rock mass GSI calculated by the improved method is mainly concentrated between 40 and 60,which is close to the calculation results of the traditional method.The GSI error rates obtained by the two methods are mostly less than 10%,indicating the rationality of the hyperspectral-digital borehole image coupled evaluation method.Moreover,the sensitivity of the fissure area ratio(Sr)to GSI is greater than that of the strength reduction factor(a),which means the proposed GSI is suitable for rocks with significant fissure development.The improved method reduces the influence of subjective factors and provides a reliable index for the deterioration evaluation of rock mass.

Determination of geological strength index of jointed rock mass based on image processing

The geological strength index(GSI) system,widely used for the design and practice of mining process,is a unique rock mass classification system related to the rock mass strength and deformation parameters based on the generalized Hoek-Brown and Mohr-Coulomb failure criteria.The GSI can be estimated using standard chart and field observations of rock mass blockiness and discontinuity surface conditions.The GSI value gives a numerical representation of the overall geotechnical quality of the rock mass.In this study,we propose a method to determine the GSI quantitatively using photographic images of in situ jointed rock mass with image processing technology,fractal theory and artificial neural network(ANN).We employ the GSI system to characterize the jointed rock mass around the working in a coal mine.The relative error between the proposed value and the given value in the GSI chart is less than 3.6%.

Estimating the properties of weathered bedrock and pile-rock interaction from the geological strength index

The effect of variable rock mass properties on pile-rock interaction poses a great challenge to the design of stabilizing piles and numerical analysis of pile-rock interaction. The paper presents a novel method to estimate the properties of weathered bedrock, which can be applied to routine design of landslide-stabilizing piles for collivial landslides. The Ercengyan landslide located in the Three Gorges Reservoir, China, is the area of interest for this study. A geological investigation and triaxial tests were conducted to estimate the basic parameters, including Geological Strength Index(GSI), uniaxial compressive strength σ_(ci) and Hoek-Brown constant m_i of intact bedrock in the study area. Hoek-Brown criterion was used to estimate mechanical properties of the weathered rock, including elastic modulus E_m, cohesion c, friction angle Φ, and normal ultimate lateral resistance p_(max). A parametric study was performed to evaluate the effect of parameterizations of GSI, σ_(ci) and m_i on the bedrock properties and p-y curves. The estimated rock mass properties were used with PLAXIS 2D software to simulate pile-rock interaction. Effect of GSI on stress at the pile-rock interface and in the rock, pile bending moment, pile shear force, and p-y curve were analysed.

Estimating Unconfined Compressive Strength of Sedimentary Rocks in United Arab Emirates from Point Load Strength Index

In this paper, three rock types including Sandstone, Mudstone, and Crystalline Gypsum were part of a laboratory study conducted to develop a dataset for predicting the unconfined compressive strength of UAE intact sedimentary rock specimens. Four hundred nineteen rock samples from various areas along the coastal region of the UAE were collected and tested for the development of this dataset and evaluation of models. From the statistical analysis of the data, regression equations were established among rock parameters and correlations were expressed and compared by the ones proposed in literature.

Estimate of Uniaxial Compressive Strength of Hydrothermally Altered Soft Rocks Based on Strength Index Tests

The purpose of this study was to clarify the relationships between results of index tests and uniaxial compressive strength (UCS) in hydrothermally altered soft rocks of the Upper Miocene, which are typical of the soft rock found in northeastern Hokkaido, Japan. Index tests were performed using point load testing machine and needle penetrometer with irregular lump specimens under forced-dry, forced-wet, and natural-moist states. The relationships between irregular lump point load strength (IPLS) index and UCS, and needle penetration (NP) index and UCS were “UCS = approximately 19 IPLS index” and “UCS = 0.848 (NP index)0.619”, respectively, in soft rocks with a UCS below 25 MPa. These relationships could be applied to on-site tests of rocks with natural moisture content. The UCS could be calculated from IPLS and NP tests on soft rocks only when UCS was below 25 MPa, using the equations obtained as a result of this study.

Influence of the roots of mixed-planting species on the shear strength of saline loess soil

In order to improve our knowledge of the mechanical effect of the roots of mixed-plantings on soil reinforcement and slope protection,the influence of roots of a mixed-planting with four herb species(Medicago sativa L.,Elymus nutans Griseb.,Puccinellia distanx(L.),and Poa pratensis L.)and one shrub species(Caragana korshinskii Kom.)were investigated on the shear strength characteristics of saline loess soil.The root distribution characteristics were assessed via a survey when the plants grew for one year.The effects of the root biomass density,the root mass ratio(RMR)of the fine roots to the coarse roots,the moisture content,and the salt content on the shear strength index of the rooted soil were analyzed via a triaxial compression test,and the mechanism of these effects was discussed.The results indicate that the biomass density decreased linearly with increasing depth.The RMR initially decreased with depth and then increased,exhibiting in a quadratic relationship.The cohesion of the rooted soil increased linearly as the biomass density increased.The cohesion of the rooted soil initially increased with increasing RMR and salt content,and then it decreased.The turning point of the cohesion occurred when the RMR was 0.6 and the salt content was 1.18%.The internal friction angle of the rooted soil initially increased with biomass density and then decreased,and the turning point of the internal friction angle occurred when the biomass density was 0.015 g/cm3.The relationships between the internal friction angle of the rooted soil and the RMR and salt content were exponential incremental and linear subtractive relationship,respectively.Both the cohesion and the internal friction angle of the rooted soil linearly decreased with increasing moisture content.

Analysis of the Anomalous Strength and Location of the ITCZ Affecting the Formation of Northern Pacific Typhoons

Using the NCEP/NCAR reanalysis dataset from 1959-2004, the location and strength of the ITCZ （Inter-Tropical Convergence Zone）, as well as their relations with typhoons in the northwestern Pacific were studied. It was found that the pentad location and strength of the ITCZ had close relations with the typhoon frequency. Higher latitude location or strengthened ITCZ were found to be favorable for the occurrence of typhoons over the Northwestern Pacific. An index was defined for ascertaining the location of the ITCZ. It was found that the index defined with the maximum value of pentad and monthly meridional shear of zonal wind speed could better describe the location of ITCZ than another index defined with the maximum value of convergence. Correlation analysis between the index of ITCZ and the maximum cloud cover in the tropics showed that there were close relations between the ITCZ determined by the index and the maximum tropical cloud belt. The strength index of an ITCZ was defined as the zonal wind speed difference at latitudes south and north of the ITCZ. It was found that there are close relations between the ITCZ intensity and typhoon occurrence in the South China Sea [10°N-20°N, 100°E-120°E] and regions east of the Philippines and near the Mariana Islands[5°N-20°N, 127.5°-150°E].

Estimation of Axial Pile Bearing Capacity According to Shear Strength Parameters of Soil

At pesent, it is very popular to estimate pile bearing capacity by use of empirical formula and physical indexes of soil provided in the design codes for civil construction in China. This paper attempts to apply mechanical indexes of soil and semi-empirical formulas, which are based on soil mechanical theories and were summarized and presented by Meyerhof in 1976, to calculate the axial pile bearing capacity. Loading test results of 24 single piles in Tianjin area have been collected and compared with the proposed calulation approach.

Accurate estimation of soil shear strength parameters

The cost and safety of geotechnical engineering are highly depending on the accuracy of soil shear strength parameters.There are three methods often used to estimate soil shear strength parameters,i.e.,moment method,3-sigma rule and linear regression method.In this study,the accuracy of these three methods is compared.Traditional linear regression method(LRM)can only offer the mean of shear strength parameters.Some engineers misuse the standard error of shear strength indexes as the standard deviations.Such misuse may highly underestimate the uncertainty and induce high risk to the geotechnical design.A modified LRM is proposed to determine both the mean and variance of shear strength parameters.The moment method,three-sigma rule and LRM are used to analyze the tri-axial test data in Xiaolangdi Hydraulic Project and three numerical shear strength tests.The results demonstrate that:1)The modified LRM can offer the most accurate estimation to shear strength parameters;2)A dimensionless formula is much preferred in LRM rather than a dimensional formula.The stress ratio formula is much better than stress relation in the shear strength parameter analysis.The proposed method is applicable to shear strength parameter analysis for tri-axial test data,direct shear test and the un-drained shear strength test of stratified clay.

Influence of degree of interlock on confined strength of jointed hard rock masses

The strength of jointed rock mass is strongly controlled by the degree of interlock between its constituent rock blocks.The degree of interlock constrains the kinematic freedom of individual rock blocks to rotate and slide along the block forming joints.The HoekeBrown(HB)failure criterion and the geological strength index(GSI)were developed based on experiences from mine slopes and tunneling projects in moderately to poorly interlocked jointed rock masses.It has since then been demonstrated that the approach to estimate the HB strength parameters based on the GSI strength scaling equations(called the‘GSI strength equations’)tends to underestimate the confined peak strength of highly interlocked jointed rock masses(i.e.GSI>65),where the rock mass is often non-persistently jointed,and the intact rock blocks are strong and brittle.The estimation of the confined strength of such rock masses is relevant when designing mine pillars and abutments at great depths,where the confining pressure is high enough to prevent block rotation and free sliding on block boundaries.In this article,a grain-based distinct element modeling approach is used to simulate jointed rock masses of various degrees of interlock and to investigate the influences of block shape,joint persistence and joint surface condition on the confined peak strengths.The focus is on non-persistently jointed and blocky(persistently jointed)rock masses,consisting of hard and homogeneous rock blocks devoid of any strength degrading defects such as veins.The results from this investigation confirm that the GSI strength equations underestimate the confined strength of highly interlocked and non-persistently jointed rock masses.Moreover,the GSI strength equations are found to be valid to estimate the confined strength of persistently jointed rock masses with smooth and non-dilatant joint surfaces.

相位角与肌少症及相关诊断指标的Meta分析

目的:系统评价相位角与肌少症及相关诊断指标的相关性。方法:计算机检索PubMed、EMbase、Cochrane Library、Web of Science、中国知网、万方、维普和SinoMed数据库,收集关于相位角与肌少症及相关诊断指标相关的临床研究,检索时限均为各数据库建库至2024-05-08。由2名研究者独立筛选文献、提取资料并评价纳入研究的偏倚风险。采用RevMan 5.3和Stata 14.0软件进行Meta分析。结果:经筛选共纳入50篇合格文献。Meta分析结果显示,与非肌少症人群对比,肌少症患者的相位角显著降低[SMD=-0.99,95%CI(-1.09,-0.90),P<0.00001]。亚组分析结果表明,重度肌少症以及亚洲肌少症患者相位角差值更加显著,并且伴有肌少症的恶性肿瘤和呼吸系统疾病患者的相位角降低更加明显。相位角与骨骼肌质量指数(Pearson’s r=0.565,P<0.00001)、握力(Pearson’s r=0.446,P<0.00001)、步速(Pearson’s r=0.405,P<0.00001)均呈中等正相关,但与四肢骨骼肌质量指数呈极弱正相关(Pearson’s r=0.139,P=0.02)。结论:与非肌少症人群对比,相位角在肌少症人群具有显著差异性,且与肌少症诊断指标均存在不同程度相关性,提示相位角在肌少症的客观诊断中具有一定的临床价值,但其结果可能受到肌少症严重程度、相位角检测仪器等因素的影响,且因受纳入研究数量和质量的限制,上述结论尚待更多高质量研究予以验证。

Prediction of the residual strength of clay using functional networks

Landslides are common natural hazards occurring in most parts of the world and have considerable adverse economic effects. Residual shear strength of clay is one of the most important factors in the determination of stability of slopes or landslides. This effect is more pronounced in sensitive clays which show large changes in shear strength from peak to residual states. This study analyses the prediction of the residual strength of clay based on a new prediction model, functional networks（FN） using data available in the literature. The performance of FN was compared with support vector machine（SVM） and artificial neural network（ANN） based on statistical parameters like correlation coefficient（R）, Nash–Sutcliff coefficient of efficiency（E）, absolute average error（AAE）, maximum average error（MAE） and root mean square error（RMSE）. Based on R and E parameters, FN is found to be a better prediction tool than ANN for the given data. However, the R and E values for FN are less than SVM. A prediction equation is presented that can be used by practicing geotechnical engineers. A sensitivity analysis is carried out to ascertain the importance of various inputs in the prediction of the output.

Strength of massive to moderately jointed hard rock masses

The Hoek-Brown (HB) failure criterion and the geological strength index (GSI) were developed for the estimation of rock mass strength in jointed and blocky ground where rock mass failure is dominated by sliding along open joints and rotation of rock blocks. In massive, veined and moderately jointed rock in which rock blocks cannot form without failure of intact rock, the approach to obtain HB parameters must be modified. Typical situations when these modifications are required include the design of pillars, excavation and cavern stability, strainburst potential assessment, and tunnel support in deep underground conditions (around σ1/σci > 0.15, where σ1 is the major principal compressive stress and σci is the unconfined compressive strength of the homogeneous rock) in hard brittle rocks with GSI ≥ 65. In this article, the strength of massive to moderately jointed hard rock masses is investigated, and an approach is presented to estimate the rock mass strength envelope using laboratory data from uniaxial and triaxial compressive strength tests without reliance on the HB-GSI equations. The data from tests on specimens obtained from massive to moderately jointed heterogeneous (veined) rock masses are used to obtain the rock and rock mass strengths at confining stress ranges that are relevant for deep tunnelling and mining;and a methodology is presented for this purpose from laboratory data alone. By directly obtaining the equivalent HB rock mass strength envelope for massive to moderately jointed rock from laboratory tests, the HB-GSI rock mass strength estimation approach is complemented for conditions where the GSIequations are not applicable. Guidance is also provided on how to apply the proposed approach when laboratory test data are not or not yet available.

Comparison of Remolded Shear Strength with Intrinsic Strength Line for Dredged Deposits

Chandler proposed the intrinsic strength line to correlate the undrained shear strength of samples one-dimensionally consolidated from slurry with the void index proposed by Burland. The undrained shear strength on the intrinsic strength line is different from the remolded undrained shear strength that is an important parameter for design and construction of land reclamation. The void index is used in this study for normalizing the remolded strength behavior of dredged deposits. A quantitative relationship between remolded undrained shear strength and void index is established based on extensive data of dredged deposits available from sources of literature. Furthermore, the normalized remolded undrained shear strength is compared with intrinsic strength line. The comparison result indicates that the ratio of undrained shear strength on the intrinsic strength line over remolded undrained shear strength increases with an increase in applied consolidated stress.

Selection of regression models for predicting strength and deformability properties of rocks using GA

Recently,many regression models have been presented for prediction of mechanical parameters of rocks regarding to rock index properties.Although statistical analysis is a common method for developing regression models,but still selection of suitable transformation of the independent variables in a regression model is diffcult.In this paper,a genetic algorithm(GA)has been employed as a heuristic search method for selection of best transformation of the independent variables(some index properties of rocks)in regression models for prediction of uniaxial compressive strength(UCS)and modulus of elasticity(E).Firstly,multiple linear regression(MLR)analysis was performed on a data set to establish predictive models.Then,two GA models were developed in which root mean squared error(RMSE)was defned as ftness function.Results have shown that GA models are more precise than MLR models and are able to explain the relation between the intrinsic strength/elasticity properties and index properties of rocks by simple formulation and accepted accuracy.

Conditional and unconditional QTLs mapping of gluten strength in common wheat (Triticum aestivum L.)

Dissecting the genetic relationships among gluten-related traits is important for high quality wheat breeding. Quantita- tive trait loci （QTLs） analysis for gluten strength, as measured by sedimentation volume （SV） and gluten index （GI）, was performed using the QTLNetwork 2.0 software. Recombinant inbred lines （RILs） derived from the winter wheat varieties Shannong 01-35xGaocheng 9411 were used for the study. A total of seven additive QTLs for gluten strength were identi- fied using an unconditional analysis. QGi1D-13 and QSv1D-14 were detected through unconditional and conditional QTLs mapping, which explained 9.15-45.08% of the phenotypic variation. QTLs only identified under conditional QTL mapping were located in three marker intervals： WPT-3743-GLU-D1 （1D）, WPT-7001-WMC258 （1B）, and WPT-8682-WPT-5562 （1B）. Six pairs of epistatic QTLs distributed nine chromosomes were identified. Of these, two main effect QTLs （QGi1D-13 and QSvlD-14） and 12 pairs of epistatic QTLs were involved in interactions with the environment. The results indicated that chromosomes 1B and 1D are important for the improvement of gluten strength in common wheat. The combination of conditional and unconditional QTLs mapping could be useful for a better understanding of the interdependence of different traits at the QTL molecular level.

Evaluation of the mechanical degradation of carbonate aggregate by rock strength tests

Aggregate degradation(AD) is one of the major reasons accounting for failure of aggregate materials, and the mechanical degradation of aggregate materials can be determined by different test methods. This process basically requires many aggregate samples and special instruments, and thus is time-consuming.The main purpose of this research is to evaluate the possibility of estimating the AD characteristics using rock strength tests and to investigate the relationships between AD properties and rock strength tests.For understanding the relationships, two common rock strength tests are employed, i.e. unconfined compressive strength(UCS) and point load index(PLI) tests. In the tests, the AD properties of 40 kinds of carbonate aggregates sampled from Iran were studied. The AD properties were determined by Los Angeles abrasion value(LAAV), aggregate impact value(AIV) and aggregate crushing value(ACV). Also,the samples are classified according to the strength and rock types, and the effect of this classification is investigated based on the relationship between rock strengths and AD properties. The results indicate that the PLI is better than UCS for evaluation of AD properties. Among rock strength tests, PLI has a closer relationship with AIV(R^2 = 0.832). Also, UCS has relative larger effects on the ACV(R^2 = 0.812) under the same loading condition. The weakest correlation occurs between LAAV and UCS(R^2 = 0.679). In view of the rational AD properties in the predictive procedure, it is possible to predict AD properties based on the strength tests and rock types. The results also show that the prediction of AD properties using rock strength test based on rock types yields better correlations than that using unclassified samples. The classification based on rock types can extrapolate the different relationships of AD prediction from rock strength tests. The results in this context could be used for preliminarily selecting proper rock aggregates with a limit of allowable AD tests for practical applications by PLI.

基于密度划分的分布式数据容错存储算法研究

为保证数据安全性,缓解数据存储空间,提出基于密度划分的分布式数据容错存储算法。过滤分布式数据高密度数据区域,将具有高度相似的目标划分到不同区域,通过数据来源样本点描述数据的密度分布,设定数据弹性,利用概率以及数据粒度推算出对应的存储梯度和强度指数,并在信息存储中引入数据存储梯度和数据弹性,完成分布式数据容错存储。实验证明,所提算法有较高的容错性,带宽吞吐量平稳,平均路径长度较小,能提高网络数据的安全性。

髌股关节痛业余跑者的下肢肌力特征分析

目的:研究髌股关节痛(patellofemoral pain,PFP)业余跑者的下肢肌力特征。方法:招募PFP业余跑者30例(男性20例,女性10例)作为膝痛组,并匹配30例无损伤的业余跑者作为非膝痛组,采集所有受试者的髋关节外展力量、股四头肌力量、腘绳肌力量,并计算腘绳肌/股四头肌比值、双侧肢体力量对称指数等。采用独立样本t检验对不同组别的各项指标进行统计学检测。结果:男性PFP业余跑者的髋关节外展力量及对称指数、股四头肌力量及对称指数显著小于非膝痛组,腘绳肌/股四头肌比值显著大于非膝痛组;女性PFP业余跑者的髋关节外展力量及对称指数显著小于非膝痛组。结论:PFP业余跑者与非膝痛跑者表现出不同的下肢肌力特征,其男性与女性PFP业余跑者下肢力量特点表现并不一致,PFP康复训练中应考虑功能性及性别差异。

基于机器学习的CFST柱高温剩余强度系数预测方法

目的 为提高计算精度和速度,利用机器学习模型泛化数据,以预测CFST柱的高温剩余强度系数。方法 利用生成对抗网络将搜集到的110个试验结果泛化生成407组数据,据此训练机器学习模型,并使用试验结果评估其性能,以确定最优模型;然后使用生成数据输入建立的模型预测CFST柱高温剩余强度系数,并和现有计算方法进行对比。结果 建立的随机森林模型在性能度量上表现最好,拟合优度达到0.947 7,均方误差为0.001 8,精度为94.7%;预测结果误差在±10%内的数据为83%,在±20%内的数据为100%;剩余强度系数主要影响因素依次为温度、钢材屈服强度、混凝土抗压强度和横截面积,钢管厚度影响很小。结论 提出的预测方法优于现有计算方法,具有更快的计算速度、更小的结果误差以及更强的模型可解释性,该方法可为CFST柱抗火设计提供参考。