Papers by Author: Qiang Yong Zhang

Abstract: Seepage is one of the major influence factors for engineering stability. In this study, the equations of hydro-mechanical coupling in dual-porosity media including the governing equations of deformation and seepage are employed. The fluid gravity in whole system is considered in the seepage governing equation. The solid displacement, pore fluid pressure and fissure fluid pressure are the unknown qualities. The finite element formulation of the governing equations are acquired after using the Galerkin discretization technique. The physical parameters are discussed here. Finally, the state equation method is applied to solve the finite element equations.

Abstract: Engineering rock mass is a highly complex grey system, it is impossible to get all the parameters of rock mass by theoretical methods or field measurement approach. Underground engineering feedback analysis method is a reliable way to improve the design, optimization and construction. Based on the field data of underground cavern of a large-scale hydro-power station, the three-dimensional finite element model is established, and orthogonal experimental design and multi-objective optimization method are used for the rapid back analysis. This method could be used for obtaining the rock parameters by inversion calculating in the underground cavern construction of a large-scale hydro-power station. Meanwhile, the inversion parameters could also be applied in the excavation simulation for the next phase and the rock deformation and stability is predicted afterwards. The design and construction sectors are supposed to get its feedback in time, which effectively guarantees the stability of the surrounding rocks.

Abstract: For the safety of salt rock underground gas storage cavern, uncertainties of material parameters and their influence to structure must be considered. In this paper, random field method is used for failure probability analysis of gas storage cavern. Random field model of material parameters is introduced firstly, local average method is used in discretization of random field, then Monte-Carlo stochastic finite element method is used in failure probability calculation. Conclusions can be drawn as follow: Failure probability in middle part of the cavern is higher than that of upside and underside, and failure probability decreases when operation pressure increasing. Middle part of cavern in release process is the most dangerous. Failure probability of cavern computed by random field model and random variable model based on response surface method are campared. It is obviously that failure prabability computed by random field is lower than that of by RSM. As variation coefficient and fluctuation range increasing, failure probability of salt rock cavern will increase.

Abstract: The center hole deformation test of rigid bearing plate is an important method for understanding deformation properties of deep weak rock mass. According to the center hole deformation test of rigid bearing plate in dam zone of Dagangshan hydropower station, this paper detailedly recommends test method of this experiment, and the settlement deformation formula of deep rock mass under circular rigid bearing plate is deduced, which could be used to calculate deformation modulus and equivalence deformation modulus of different deep rock mass at test points. According to curves of depth-deformation under different pressures at test points in dam zone, we have analyzed deformation characteristics of deep weak rock mass. By the center hole deformation test of rigid bearing plate, stratum properties in dam zone of Dagangshan hydropower station could be understood further, and it provides important references for the study of creep speciality of weak rock mass in dam zone.

Abstract: This paper introduces many types of analogue materials in China and other countries in geotechnical model tests. Combined with the study on a few geo-mechanical model tests of significant tunnels and underground openings in Chinese western areas, this paper recommends a new type of analogue material, which is made from iron mineral powder, barite powder, quartz powder and alcoholic solution with rosin. In order to know the physico-mechanical characteristics of this composite material with different mixture ratios, we use specimens to do lots of mechanical experiments such as uniaxial compressive test, quasi-triaxial shear test, triaxial test and Brazilian test. Consequently, the analogue materials with different mixture ratios can be used to physically model different projects, and this analogue material with a certain mixture ratio has been successfully used in the model test of a branching-out tunnel. The results of the model test verify that this new analogue material can be successfully used in all kinds of geotechnical model tests.

Abstract: Due to lots of hypothesis, the theoretical analytical solution of the creep parameters inversion can not reflect the in-situ conditions actually. In order to simulate the process of the compressive creep tests of the in-situ bearing plate, the affection of the stratum distribution and the influence of the geological status in site actually, FLAC3D is used and numerical back analysis method of the creep parameters at dam site is set up. Based on the in-situ compressive creep tests’ data of the diabase rock masses at Dagangshan dam site, creep parameters are got with this method. Results indicate that the numerical calculated displacements of the compressive creep are similar to the in-situ monitoring displacements. It reveals that with this numerical method creep parameters can be backing analyzed logically. This supplies technical assurances to stability estimate and analysis of rock masses in slope projects.

Abstract: As the implementations of the western development in China, more and more tunnels will get through the western mountains in China. In order to economize the construction costs, a new type of underground structural form called branching-out tunnel must be applied. The failure process of the branching-out tunnel under lateral overload action is also greatly complicated, which is related with the depth of the mountains, the branching-out angle, the in-situ stress field, the thickness of the middle wall and so on. This paper uses the 3D-physical model of geo-mechanical model tests to study the stability and failure process of this complicated structure, especially the part of the middle wall. The physical model is built up in a new kind of analogy material. In the process of the whole experiments, different lateral pressures imposed on both of the lateral planes of the physical model. According to different lateral pressures, we have attained the change of the stress and displacement field and looked into the failure process of the pivotal positions in the branching-out tunnel. We also use finite element method analysis software RFPA (Realistic Failure Process Analysis) to simulate the whole failure process of the branching-out tunnel. Finally, we have got the load-bearing safety reliability of this complicated structure through comparative analysis of physical modeling and numerical simulation.

Abstract: The geological radar is an advanced non-destructive geophysical prospecting technology used in detecting the invisible and abnormal underground objects. In this paper, this technology is used in the large-scale highway landslide treatment. The location and size of the cavity, fissure and fracture zone in the landslide body is identified accurately. The supporting design and reinforcement construction for the landslide is performed according to the testing results, which ensures the slope stability and the normal operation of the highway, and significant economic benefits have been achieved.

Abstract: Geomechanics model test has some distinctive advantages in simulating changing laws of stress and strain of rockmass as well as failure mechanism of surrounding rockmass of tunnel. In order to systematically study mechanics deformation properties of a large-scale offspur tunnel under excavation state, we design and manufacture a large scale 3D model test rack installation with hydraulic equipment. The test rack is 3.7 meters long, 2.2 meters wide and 4 meters high, which is the largest 3D geomechanics model test rack in present Chinese communication trades. The new-type similar material of model is a kind of cementitious composite which is mixed with iron ore powder, blanc fix, quartz sand, rosin, industrial alcohol and gypsum powder. 3D geomechanics model test for a large-scale offspur tunnel is carried out by utilizing the test installation and the similar material. The original design and construction of the offspur tunnel has been effectively optimized by results from model test.

Abstract: It is very important to choose a similar material which simulates rock mass correctly in geo-mechanics model test. In this paper, we introduce similar material research status and analyze the principle of selecting and compounding. According to the experiences of similar material research, we develop a new similar material (we call it iron barites sand cementation material, abbreviate IBSCM) through hundreds of compounding experiment. This similar material is made up of iron ore powder, barites powder, sand, rosin, alcohol and gypsum powder. Iron ore powder, barites powder and sand are main materials, the solution of rosin and alcohol is glue, and gypsum powder is regulator. Specimen mechanics tests show that different rock mass can be simulated by the model materials with different materials compounding. The new similar material is easy to buy and its price is cheap, and it has some advantages, such as high density, stable performance, easy dryness, and easy cutting. The new similar material can simulate a lot of rock mass, so it is an ideal similar material. At last, we apply this new type similar material to tunnel geo-mechanical model test and gain the ideal result.