AN ANALYSIS ON ELIMINATING NOISE OF AE TEST BY SIMULATOR AND THE KAISER EFFECT

In the utilization of the Kaiser Effect of AE as a method of estimating the gecstress in rock, it is very important to eliminate the noise induced at the ends cf a specimen, so sponge pads are put between the upper and lower end surfaces of specimens and bearing plates. In this paper, the attenuation behavior of sounds emitted by AE simulator and propagating in sponges are quantitatively measured. The eliminaion of noise by sponge effect is confirmed by the Kaiser Effect.     

The Catastrophic Theory Model of Instability of Coal and Rock Mass

In this paper,the stability problems of coal and rock mass exerted by horizontaland vertical forces are studied with the help of the method of catastrophic theory. The expression ofthe total potential energy function for this system is derived. This system can be described by thecusp catastrophe model. The bifurcation set which makes this system to loss its stability in the hori-zontal and vertical force control space is obtained. At the same time ,the process of Sudden statechange of coal and rock due to the changes of horizontal and vertical forces is discussed.     

Frequency Hydraulic Aperture about Fracture Seepage in Rock Mass

The frequency aperture given in this paper is a new method that describes the fracture aperture composition. The aperture curve plays a role in describing the aperture distribution and uniformity. In particular, the frequency hydraulic aperture is of great importance in seepage analysis. It overcomes limitations of hydraulic aperture and mean aperture. Based on existing information, the result of example calculation shows that the hydraulic aperture e h equals to the median aperture e 50 . This paper also obtains that the frequency hydraulic aperture e sh equals to e 48 through finite element numerical modeling for various type of random fracture.     

Research on Index of Reliability for Bearing Capacity of Rock - Socketed Single Pile in Chongqing

Based on the data from in-situ 102 rock-socketed test piles in Chongqing in recent 10 years and utilizing the limit state equation of the dimensionless random variables,the reliability analysis of the bearing capacity of rock-socketed single pile is made and the scope of the target reliability of rock-socketed piles in Chongqing is calculated with both JC method and Monte-Carlo method respectively.Furthermore,the target index of reliability is suggested.Finally,the concept of reliability coefficient(to replace the load partial factor and the resistance partial factor) is given and the bearing capacity of the single pile is determined by utilizing optimization method.Besides,the practical limit state design equation using reliability coefficient is put forward for its advantage of incarnating the simple and practical principle and being easy mastered and understood by the designers.     

The Criterion Tor Shear Strength of Discontionuties with Different Rock Properties in Rock Mass

In this paper,with shear device, shear test of discontinuties with different rockproporties in rock mass under various surface roughness and different normal stress is investigated,the com mon shear strangth criterion of discontin uties is set up as follows.     

Complex Variable Function Solution of Stress and Displacement of Surrounding Rock Buried Deep Horseshoe-Shaped Tunnel Excavation

An analytical solution was presented for the stresses and displacements around horseshoe-shaped tunnel using Cauchy integral method and Optimization theory in an elastic half-plane. Since the depth of a tunnel was larger than the size of the tunnel, gravity loads were simplified as uniform normal loads along far-field boundary. Finite element model was used to verify the accuracy of analytical solutions. Comparison between the results of numerical analysis by finite element method and those from the closed solutions indicates that the closed solution is reliable and applicable for the stress and displacement field around horseshoe-shaped tunnel tunnels at great depth.     

Discussion on Some Problems of ExpertSystem for Rock Mass Classification

On the basis of discussing present situation for classification of rock masses and necessity of building expert system of rock masses.The intelligent design software for classification of rock masses CRES has been completed. In this paper the CRES is expounded systematically in the following,such as knowledge_base,data_base,reasoning machine,learning machine,and so on.Finally,the CRES is used for verifying 30 engineering examples and is used to classify rock masses of two roadways successfully .The CRES has been connected to SBSDES.     

Analysis of Damage Localization in Crack Weakened Rock Mass

Damage localization in crack weakened rock mass is closely related to the crack growth pattern. Bifurcation of the alternative evolution of cracks occurs when the cracks grow to some extent, then some cracks keep on growing while other ceased evolving. It is found that damage localization in crack weakened rock mass is caused by bifurcation of the crack growth pattern, and the initial location is also determined by the crack growth pattern. Based on the analysis on the bifurcation of crack growth pattern, the critical length of wing crack and the critical stress of damage localization in crack weakened rock mass are obtained. Subsequently, the onset location of damage localization is determined by using the eigenvalue and eigenvector of coefficient matrix, and crack interaction is also taken into account in this model. Finally, the relationship between the interval between columns and rows, the orientation of crack, confining stress and the critical stress of damage localization is defined in the example.     

Experimental Study on the Characteristic of Seepage with Unloading Rock Mass

The destruction of rock mass arises from opening rock possibly, the main outside-factor of influence rock slope stability is groundwater and water seepage. To analyze the relationship of unloading and permeability coefficient, the method and step of experiment of unloading rock mass are put forward. The curve relationship of the seepage-unloading of different phase is found by experiment. According to the experimental result, the equation of the seepage-stress of unloading is established, the variational rule of the unloading and permeability coefficient is discussed. The permeability coefficient is almost unchanged in the elasticity phase of unloading process. The permeability coefficient changes very much in the plastic phase of unloading process, as the unloading is 80% of ultimate unloading especially, and the permeability coefficient is increasing very much.     

基于EC-Probe仪器的土壤盐分原位测定及其在河北坝上地区的应用研究

目前中国测定土壤含盐量主要使用土壤浸提液法,而这种传统的方法操作繁琐,原位测定法相对更为便捷,但应用较少。使用EC-Probe仪器原位测定河北坝上部分地区土壤电导率,部分土样采用实验室土壤浸提液电导率法建立土壤盐分与土壤电导率之间的转换模型,通过该模型对坝上地区不同土地利用类型同一深度的土壤盐度进行测量,并分析了不同深度土壤盐度分布的主要规律。结果发现沼泽、耕地、森林、河漫滩和草地的土壤含盐量依次下降,研究发现该研究区域目前各种土地利用类型的土壤盐度均未达到盐碱化标准,但沼泽地和耕地的盐碱化风险较高,需加强生态保护。     

The Unloading Effect of Rock Samples and the Quality Evaluation of Engineering Rock Masses

For most evaluating methods of engineering rock mass, the integrality index is an important assessment factor. However, sometimes the value of integrality index would be more than 1.0 because of unloading effect of rock samples and differentia of frequency between the measurements of rock samples and rock mass. In order to solve this problem, unloading index and frequency correcting coefficient were put forward to revise the integrality index. Moreover, the BQ evaluating method proposed in the national standard (GB 50218-94) was improved with the revised method. With the case study of the project of water sealed underground oil tank in Huangdao, it was found that the quality of rock mass in the site was grade I or II.     

Damage Constitutive Equation and Experiment of Layered Rock

The microcosmical study on many speciments of sedimentary rock by SEM and petrography theory show that rock is formed of microcrystalline and micropore with all kinds of forms.Therefrom the microstructure model of rock is established.Further the three dimensional nonlinear damage constitutive equation and damage evolution equation of layered rock including respective process of damage evolution,mechanical parameter,effective stresses,and unequal biaxial stress in different rocks are derived.The results of the experiment indicate that the theoretical curve is fairly close to the experimental curve.     

Research on X-Ray Computer Tomography for Measuring Residual Stresses of Beryllium Weldment

Beryllium is a light rare metal, which is broadly used in nuclear energy, aviation and aerospace industry. As a structural material, the residual stresses in it during processing have a harmful influence upon its products in use. So it is very important to measure the residual stresses. Overcome the shortcoming of traditional X ray residual stress measuring techniques, X ray computer tomography is presented. This technique used in the present analyzer can non-destructively measure light metals' residual stresses with depth resolution, such as beryllium, by altering measuring and evaluating method. The residual stresses at the surface nearby welding of arc Beryllium weldment , the depth of 0.5 mm and 1.0 mm under the surface are evaluating by X ray computer tomography, meanwhile the stress free lattice spacing, d 0 , of beryllium (103) plane is calculated with this technique. The result shows that d 0 is closed to the one calculated by the lattice spacing formula of crystallograqhy.     

MECHANICS OF COATS FROM PAINTING AND PLATING AND DAMPING PROPERTIES IN CYLINDRICAL SHELLS WITH OUTER COATS

A mechanical model of coats is proposed to approach general theory and method in analysing it,and damping properies,stresses in coats and stresses between coats and body in a cylindrical shell with outer coats are given too.     

Application of Joint Element in the Stability Analysis of Rock Mass

According to the strongpoint and shortcoming of all kinds of plane joint elements and theirs applicable range, the basic theories of plane joint elements were introduced in brief. An example which utilized different plane joint elements to simulate the different sorts of discontinuity interface in rock mass was given, and the analysis result indicates that if only the constitutive model of a material is confirmed ,and some special element types are adopted,with the basic principle and approach of the finite element to simulate rock materials, a more satisfactory result can be obtained.     

The Influence of In-situ Stress Gradient and Geothermal Temperature on The Calculation of Coalbed Gas Pressure

On the basis of coal seam having outcrop of coal seam and outlet on ground,the method for calculating coalbed gas pressure from the one-dimensional stable gas flow equation by considering deeply the influence of in-situ stress gradient and geothermal temperature is presented. In some mine, the theoretically computing and measuring results of coalbed gas pressure show that the in-situ stress gradient and the geothermal temperature have important influence on the calculation of coalbed gas pressure, and if the factors are drew into the calculation of coaled gas pressure,it will make the results much more accurate.     

Epigenetic Reformation of Rock Mass in Dam Area of Xiluodu Hydropower Station

By investigating the space development rule of the epigenetic deformation and fracture trace and the combination pattern of epigenetic structure in dam area of Xiluodu hydropower station, the formation mechanism of epigenetic reformation is discussed in conjunction with the analysis of geologic physiological evolvement mechanism. Slaty rock mass structures which being made up of flat faults have played important role in controlling epigenetic reformation. The typical combination pattern of epigenetic structure is formed from steep dipping and flat faults. It is very important for understanding the feature of valley rockmass structure.     

Discussion on Methods for Determining Cracking Angle of Rock Slope

Many mountainous cities are facing slope problems during project construction. At present, there are two methods to determine cracking angle for rock slope, namely, the method from "Technical Specification for Retaining Structure in Excavation" and the method from "Handbook of Engineering Geology". However, there is obvious difference between cracking angles of rock slope by these two methods. In this paper, the theoretical formulas of these two methods are derived and compared. Based on analyzing the results of FLAC numerical simulation for soft rock slope, it is concluded that the cracking angles of rock slope determined by the "Handbook of Engineering Geology" are more reasonable and safe.     

The Dissolution Characteristics of Rock Salt and Mass Transmission Process

The dissolution separation of halite from rock salt and the mass transmisson of sodium chloride (NaCl) solution forming the dissolution process of rock salt are investigated. With the experimental studies of the dissolution characteristic of rock salt and the diffusion of sodium chloride (NaCl) solution. The changing regularity of the dissolution rate of rock salt and the separation coefficient with each primary influence factor,as well as the corresponding formulae are obtained. The dynamic differential equilibrium equations of rock salt solution are established.     

Relationship Between Dynamic and Static Value of Elastic Modulus in Rock

Taking the deposited-layer rock and compacted-layer rock as study target,by elastic wave experiment and uniaxial compression experiment,the physics mechanics parameters and acoustics parameters of these rock are worked out; Based on it, by the correlativity is established between dynamic and static value of elastic modulus in rock of different lithology taking nonlinear fitting,it offers reference for the study of the drill and measuring well in the exploitation of oil. Influenced by the integrality and weathering breakage degree of rock,the biggish different is existed between dynamic elastic modulus gained by dynamical method and static elastic modulus obtained by static method,and the relationship between dynamic and static value of elastic modulus is approximatively expressed as a relationship of quadratic polynomial function.