Papers by Author: Xiao Jing Li

Abstract: The anchorage force loss of the prestressed anchor rope results in reduction or loss of anchorage force, which poses an enormous threat to the project safety. In the conceptual design process, factors like the system , structure, spacing and tonnage of anchorage, and properties of rock and soil should be considered and measures should be taken to effectively control or reduce the effect of the anchorage force loss, which possesses great theoretical and practical significance on the design, construction , safety and social-economic benefits of the anchorage project. Finally, the validity and reliability of design measure was proved by an engineering example.

Abstract: The changing rule of excess pore water pressure during dynamic compaction is important for construction. The following conclusions could be drawn by observing and analyzing the excess pore water pressure in test area. Under ramming strike energy of 2000kN•m, the best hit number during the 1~2 times is 8~9, the best hit number during the third time is 6~8. After compaction, the shallow excess pore water pressure is basically larger than the deep. The shallow excess pore water pressure needs more time to dissipate. The horizontal distance of the shallow excess pore water pressure is larger than that of the deep. During the dissipating process of the pore water pressure, we should pay attention to avoid vibration interference of load in the surface and prevent liquefaction of the powder soil. Under ramming strike energy of 2000kN•m, the biggest influence depth of dynamic compaction is 8～9m, the effective reinforcement depth is 6～8m. The conclusions can provide the theoretical basis for dynamic compaction construction.

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: The jointed rock mass distributed in the nature widely and its mechanical characteristic influenced the stability of the rock engineering badly. The cracks propagated and coalesced each other and macroscopic failure happened. Bolts were a kind of effective reinforcement instrument and they could prevent the cracks from propagating. However, the anchoring mechanism of bolts was not realized clearly and their reinforcement could not be reflected effectively in the numerical simulation yet. Based on the damage mechanics, a constitutive relation and damage equation of anchored jointed rock mass were presented in this paper. With a project application, the model was proved to be feasible one.

Abstract: Considering the time effect of surrounding rock and the long time stability of the underground caverns after being excavated, a method on the finite element viscoelastic displacement based on Kelvin model. The recursion formula is obtained by the displacement analytic solution of Kelvin model. It can be used to predict the viscoelastic displacement development fast and accurately. Finally this method is employed into a project, and the calculated values by this method agree well with the measured values. Prove that the method is effective.

Abstract: Based on the underground structure scheme of Langyashan hydro-electrical project, lots of elastic-plastic numerical analysis were conducted considering modulus of deformation, layout depth of underground opening, height of main factory premises, coefficient of lateral compressive stress, as the mainly mechanical parameters that influenced the stability analysis of underground openings. The mathematical statistics method was employed to investigate the displacement variation law of key point surrounding house periphery and found the forecast model. Then the forecast model was used to analyze the sensitivity parameters. It was shown that there was a good agreement between theoretic result and monitoring result in situ.

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: According to the theories of fracture mechanics and damage mechanics, the constructive model and fracture damage mechanism of brittle discontinuous jointed rockmass are systematically studied under the state of complex stress in this paper. By the aid of the method of equivalent strain energy, the constitutive relation of anchored brittle discontinuous jointed rockmass is derived under the state of compression-shearing. The constitutive relation under the state of tension-shearing is also developed according to the theory of self-consistence. Finally, based on the above constructive models, the three-dimensional finite element procedure has been developed to model the ground movements that occur when underground power-houses of pumped-storage power station are installed in discontinuous jointed rockmass. The anchor supporting is an important component of this underground power-houses excavation work. Besides the displacement field and the secondary state of stress induced by the excavation disturbance, the effect of anchoring and the damage evolution around the power-houses have been particularly described during the process of installation. The numerical results obtained by numerical simulation were compared with that of field monitoring in order to verify the validity of the proposed models.