抽采钻孔瓦斯浓度原位检测技术及应用

准确检测瓦斯抽采参数对指导抽采负压调节,保障煤矿安全抽采具有重要意义。针对现有瓦斯抽采参数检测技术对于准确测量钻孔内原位瓦斯浓度存在困难的问题,基于激光检测原理设计了一种抽采钻孔瓦斯浓度原位检测设备。基于比尔-朗博定律推算瓦斯气体浓度解算公式,在此基础上完成了瓦斯抽采参数原位检测设备总体结构设计及瓦斯浓度传感器设计,开展了实验室设备性能测试及现场应用试验。研究结果表明,设备的相对误差、稳定性和响应时间均满足行业标准,同时该设备能够有效实现钻孔沿程瓦斯抽采参数检测,检测数据为煤矿高效负压调节及智能化开采提供数据支撑。

Estimation of Undrained Bearing Capacity for Offshore Soft Foundations with Cyclic Load

The degradation strength of soils under cyclic loading is studied and a method for determining the cyclic degradation strength with cyclic triaxial tests is given in the paper. Furthermore, a dum my static method for estimating the undrained bearing capacity for offshore soft foundation under wave loads is developed. It can consider the effect of the difference of cyclic stress for different parts of the foundation on both the degradation strength of the foundation soil and the bearing capacity so that the estimated result can better reflect the real condition of foundation under cyclic loading. The method can be applied to plane and space problem.

Dynamic Behaviour of a Caisson Quaywall Under Strong Earthquake

Effective stress analysis is performed to evaluate the residual displacement of a caisson quaywall during 1994 Hokkaido- Toho- Oki Earthquake and 1993 Kushiro- Oki Earthquake. The constitutive model used in this study is a multiple shear mechanism type defined in strain space and can take into account the effect of rotation of principal stress axis. The earthquake accelerations recorded at the outcropping rock during the earthquake are used as input bedrock motion. The results of finite element analysis are in good agreement with the observed behaviour of the quaywall. The analysis also indicates that liquefaction and high excess porewater pressure have a significant effect on the deformation of the caisson. Soil improvement is speculated as the most reliable measures against liquefaction. The influence of soil improvement and the reasonable improved area are discussed in the paper.

Analytic Solution of Elasto-Plastic Stress in Infinite Slope under Uniform Load

According to the Mohr-Coulomb yield criterion, the stress field of the infinite slope is derived under a vertical uniform load q on the top of the slope. It is indicated that elastic and elasto-plastic states would occur in the slope. When q is smaller than the critical load, q(p), the slope is in the elastic state. If q equals q(p), the slope is in the critical state, and the plastic deformation would occur along the critical angle. With the increase of q, the plastic zone would extend, and the slope is in the elasto-plastic State. If q equals limit load, the slope is in the limit equilibrium state. The slope may be divided into three zones. Some charts of the critical angle, the critical and limit load coefficients are presented in this paper.

The Major Controlling Factors and Different Oolitic Shoal Reservoir Characteristics of the Triassic Feixianguan Formation,Eastern Longgang Area,NE Sichuan Basin,SW China

Based on comprehensive analyses of occurrence,petrological observation,pore structure and geochemistry,the different reservoir characteristics and reservoir evolutionary pathways between different oolitic shoal reservoir types of the Feixianguan Formation on the west side of the Kaijiang-Liangping Trough have been studied.There exist three stages of high-energy slope break belts in the Feixianguan period,the corresponding three stages of oolitic shoals gradually migrating in the direction of the trough.Three types of oolitic shoal reservoirs,namely,residual-oolitic dolomite,mold-oolitic dolomite and sparry oolitic limestone,were formed during sedimentary-diagenetic evolution,the pore types being intergranular dissolved pore,mold pore(or intragranular dissolved pore)and residual intergranular pore,respectively.The petrology,physical properties and pore structure of the different types of oolitic shoal reservoirs are quite different.Residual-oolitic dolomite reservoirs have the best quality,while sparry oolitic limestone reservoirs have the poorest.Combined with analyses of trace elements,rare earth elements and carbon-oxygen isotopes,it is suggested that the formation of residual-oolitic dolomite reservoirs is jointly controlled by penesaline seawater seepage-reflux dolomitization and hydrothermal dolomitization.Mold-pore oolitic dolomite reservoirs are controlled by penesaline seawater seepage-reflux dolomitization and meteoric water solution.The burial dissolution of organic acid not only further improves the reservoir qualities of previously formed oolitic dolomite reservoirs,but also preserves residual intergranular pores in the sparry oolitic limestone reservoirs.

基于U-Net的岩层图像裂缝检测算法应用

为快速检测工程和煤矿矿山的岩层状况,实现对岩层图像的裂缝检测,提出一种基于U-Net的岩层图像裂缝检测算法。采用随机平移与旋转的方式扩充原始数据集,使数据量为原始数据的11倍,并以扩充后的数据集为训练集,较好地解决了数据量不足的问题;图像预处理结合加权平均法和自适应中值滤波算法,保留了裂缝特征信息,提高了检测效果;新增批量归一化(batch normalization, BN)层和修正线性单元(rectified linear unit, ReLU)激活层到网络中,用深度可分离卷积(depthwise separable convolution, DSC)替换普通卷积,增强了网络性能,加快了模型学习速度,得到一个更快、更小的网络模型;使用Adam优化算法,结合均方误差(mean squared error, MSE)损失函数处理训练模型,降低了损失值,提高了精确度。实验结果表明,相较于其他以原始U-Net网络结构为基础的算法,该算法对岩层图像的裂缝检测效果更明显,收敛速度更快,精确度更高,能较好辅助工程勘测,完成检测任务。

Characteristics of Shale Reservoir and Sweet Spot Identification of the Lower Cambrian Niutitang Formation in Northwestern Hunan Province, China

The accumulation and productivity of shale gas are mainly controlled by the characteristics of shale reservoirs;study of these characteristics forms the basis for the shale gas exploitation of the Lower Cambrian Niutitang Formation(Fm),Southern China.In this study,core observation and lithology study were conducted along with X-ray diffraction(XRD)and electronic scanning microscopy(SEM)examinations and liquid nitrogen(N2)adsorption/desorption and CH4 isothermal adsorption experiments for several exploration wells in northwestern Hunan Province,China.The results show that one or two intervals with high-quality source rocks(TOC>2 wt%)were deposited in the deep-shelf facies.The source rocks,which were mainly composed of carbonaceous shales and siliceous shales,had high quartz contents(>40 wt%)and low clay mineral(<30 wt%,mainly illites)and carbonate mineral(<20 wt%)contents.The SEM observations and liquid nitrogen(N2)adsorption/desorption experiments showed that the shale is tight,and nanoscale pores and microscale fractures are well developed.BJH volume(VBJH)of shale ranged from 2.144×10^-3 to 20.07×10^-3 cm^3/g,with an average of 11.752×10^-3 cm3/g.Pores mainly consisted of opened and interconnected mesopores(2–50 nm in diameter)or macropores(>50 nm in diameter).The shale reservoir has strong adsorption capacity for CH4.The Langmuir volume(VL)varied from 1.63 to 7.39 cm^3/g,with an average of 3.95 cm^3/g.The characteristics of shale reservoir are controlled by several factors:(1)A deep muddy continental shelf is the most favorable environment for the development of shale reservoirs,which is controlled by the development of basic materials.(2)The storage capacity of the shale reservoir is positively related to the TOC contents and plastic minerals and negatively related to cement minerals.(3)High maturity or overmaturity leads to the growth of organic pores and microfractures,thereby improving the reservoir storage capacity.It can be deduced that the high percentage of residual gas in Niutitang Fm results from the strong reservoir storage capacity of adsorbed gas.Two layers of sweet spots with strong storage capacity of free gas,and they are characterized by the relatively high TOC contents ranging from 4 wt%to 8 wt%.

山区水库蓄水诱发库岸滑坡稳定性分析及处治措施研究

依托贵州山区构皮滩水电站筲箕湾库岸滑坡,介绍了滑坡特征,分析水库蓄水浸泡及冲刷坡脚为滑坡体主要诱因。采用条分法及数值模拟对下滑坡稳定性进行了计算分析,根据稳定性分析确定并采取了“抗滑桩+削坡挡土+截排水”的治理方案。采用数值模拟结合监测数据分析的方法,对治理后的滑坡稳定性进行了分析,表明治理后滑坡体外部变形量较小,治理后滑坡整体处于稳定状态。

Lithostratigraphy of Nigeria—An Overview

Nigeria lies very close to the equator(hot country) at the west coast of Africa between latitude 4°-14°N and longitude 2°-15°E.The country is located at the northern end of eastern branch of west coast of Africa rift system.Nigeria geological setting comprises broadly sedimentary formation and crystalline basement complex,which occur more or less in equal proportion all over the country.The sediment

Integrated geophysical surveys on railroads in permafrost areas

The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engineer-geologist survey been held in railway industry. This paper presents general issues concerning railway construction and operation in permafrost areas. Comprehensive geophysical methods to monitor the development of thawed soils axe considered in detail. The main physical parameters which help define permafrost and thawed soil patches are described. Author of current paper pointed out main factors, allowing predicting potential areas of development of thawed grounds. They offered set non-destructive methods： GPR investigations, seismic survey and elec- tric exploration. Whole sets of geophysical data： electric resistivity, velocity of S-wave and P-wave （and their correlation）, allow us with high confidence specify characteristics and state of soil either under the line of road, or near it. At the same time the meth- od allows to predict direction of further development of thawed ground area.

Vibration diagnostics of weak base embankments

In this paper the theoretical background was analyzed for vibration diagnostics method and experience in its application for weak base embankments. General schemes of survey and recommendations on hardware systems and further prospective development are outlined.

A GENERAL SOLUTION FOR STATIC PIEZOTHERMOELASTIC PROBLEMS OF CRYSTAL CLASS 6mm SOLIDS

In this paper, a general solution for three-dimensional staticpiezothermoleastic prob- lems of crystal class 6mm solids ispresented. The general solution involves four piezoelastic potentialfunctions and a piezothermoelastic potential function, of which fourpiezoelastic potential functions are governed by weighted harmonicdifferential equations. Compared with the general solution given byAshida et al., in which seven potential functions are introduced, thegeneral solution proposed in the Present paper is more rigorouslyderived.

NON-LOCAL CONTINUUM MODEL AND ITS NUMERICAL SIMULATION FOR LOCALIZATION PROBLEM

A non-local continuum model for strain-softening simply takingplastic strain or damage vari- able as a non-local variable isderived by using the additive decomposition principle of finitedeformation gra- dient. At the same time, variational equations,their finite element formulations and numerical convolutedintegration algorithm of the model in current configuration usuallycalled co-moving coordinate system are given. stability andconvergence of the model are proven by means of the weak convergencetheorem of gen- eral function and the convoluted integration theory.

A Study on the Shear Strength Characteristic of Unsaturated Red Clay

The red clay in Chenzhou, Hunan province is mostly in unsaturated state. Simply applying the mechanical properties that derived from classic saturated soil mechanics often leads to slope failures in this region. In order to study the shear strength characteristic of unsaturated red clay in Chenzhou and to explore a shear strength equation that can be easily applied in engineering practice, a series of triaxial tests of saturated and unsaturated red clay samples were performed using the regular triaxial testing apparatus. The testing results show that the peak strength of red clay drops slightly before the moisture content of 30% but decreases sharply after that. The friction angle of red clay under unsaturated state is basically equal to the effective friction angle under saturated state, while the cohesion of unsaturated red clay is far much bigger than that of saturated one, which indicates that the matric suction makes a great contribution to the cohesion. By fitting the testing results with appropriate curves, the relationships between total strength parameters and with moisture content were obtained. The total increases logarithmically before the moisture content of 35% then decreases linearly, while decreases cubically with increasing moisture content.

FREE AXISYMMETRIC VIBRATION OF TRANSVERSELY ISOTROPIC LAMINATED CIRCULAR PLATES

Based on the three dimensional elastic theory, the state equationfo the axisymmetric free vibration of transversely isotropic circularplates is established. Taking the advantage of finite Hankeltransform, tow exact solutions are derived for two boundaryconditions, i.e. the rigid-slipping boundary and elastic simplysupported boundary. Finally, numerical results are presented and com-pared with those of FEM.