Wei Shen Zhu

Study on Seepage Field of Artificial Water Curtains for Underground Petroleum Storage Caverns in Fractured Rock Mass

Based on joint statistics from the in-situ survey, using numerical simulation technique of joint network (Monte-Carlo method), the calculation model of fractured rock mass is generated. Underground seepage discharge filed in fractured rock mass surrounding storage caverns is analyzed by using distinct element method. The result of simulation has shown good agreement with surveying data. Two cases have been simulated that is water curtains is installed and is not installed. Water pressure distributions in joints are investigated in these two cases. It is shown that in the case without water curtain the groundwater in joints which locate the upper of underground caverns is drained out and water sealed conditions is completely unrealized. When water curtain pressure is set at 0.3MPa, can underground water seal the storage caverns.

Research on Seepage Field of Underground Petroleum Storage Caverns in Fractured Rock Mass

Underground seepage discharge field in fractured rock mass surrounding storage caverns is analyzed by using discrete element method and stochastic joint-generation method. Meanwhile water pressure distributions in joints are investigated with a series of curtain pressures and compared with no water curtain. In the case without water curtain the groundwater in joints which locate the upper of underground caverns is drained out and water-seal conditions are completely unrealized. When the water curtain pressure is less than a certain value, the joints that have been drained out can not be saturated, and only the water curtain pressure exceeds this certain value, can groundwater seal the storage caverns.

Analysis of Shear Test for Jointed Rock Sample Using DDA Method

Based on a shear test for jointed rock sample conducted by former study, a numerical improved method DDARF is carried out to simulate the shear test. The simulation result of shear fracture phenomenon show high compatibility with the model test. Different fracture phenomenon and peak strength value of shear testing are explored in the condition of different colinnear and ladder echelon arrangement of cracks.

Stability Study on Jointed Rock Mass Affected by Fissure Water Pressure

Joints and fissures have a strong impact on the stability of engineering rock mass. In this paper, a self-improved analysis program of FLAC3D is adopted to study problems in fluid-solid coupling field. Then, by simulating the excavation process of a slope under the effect of fissure water pressure, the crack initiation and propagation in engineering rock mass reappears. Besides, the numerical simulation results are decent and effective, which can provide some references for engineering application.

Numerical Analysis on the Failure Process of Jointed Rock under the Effect of Seepage

In this paper, we have developed a seepage-damage coupling analytical procedure based on FLAC-3D, which can simulate and analyze the crack initiation, propagation and coalescence process of jointed rock under coupling effect. It simulates the failure process of inhomogeneous specimen with two existing fractures under pore water pressure and biaxial loading. Meanwhile compare the results with corresponding non-seepage working condition. By showing the dynamic damage state and analyzing the stress-strain relationship, the mass damage and progressive failure process of jointed rock under the influence of seepage were studied.

Testing Study on Rock-Like Materials under Water Pressure Conditions

According to test exploration and research, the authors developed a multiaxial compression testing machine and water injection pressure device. Using the device, the authors carried out a multiaxial compression testing of transparent rock-like material successfully under water pressure condition. It has important meanings to the study on the engineering characteristic of fractured rock under pressurized water conditions.

A New Method to Determining the Strength Parameters of Fractured Rock Mass

A Hydropower Station is located in the middle reach of the Dadu River in southwest China. The natural slope angles are generally 40°~65° and the relative elevation drop is more than 600m. Complex different fractures such as faults, dykes and dense fracture zones due to unloading are developed. Many abutment slopes were formed during construction of the abutments. The stability of these steep and high slopes during construction and operation period plays an important role for the safe construction and operation of the hydropower station. According to the statistical distribution of joints and fractures at the construction site, the slope is divided into a number of engineering geological zones. For each zone, a stochastic fracture network and a numerical model which is close to the real state of the fractured rock mass are established by the Monte-Carlo method. The mechanical response of fractured rock masses with different sizes of numerical models is studied using FLAC3D. The REV characteristic scale is identified for rock masses in the slopes with stochastic fracture network. Numerical simulation is performed to obtain the stress-strain curve, the mechanical parameters and the strength of the jointed rock mass in the zone. A constitutive relationship reflecting the mechanical response of the jointed rock mass in the zone is established. The Comparison between the traditional method and the method in this paper has been made at the end.

Research on Seepage Field in Fractured Rock Mass of Underground Oil Storage Cave Using Distinct Element Method

The distribution of hydraulic pressure in fractured rock mass surrounding caverns after excavation and technique of stochastic generation of joint network are investigated based on discrete element method. In order to seal the oil in underground caverns with water in the actual engineering, a water curtain with water pressure is installed, and the changes of hydraulic pressure are simulated with a series of curtain pressures. It is shown that some joints that have been drained out during excavation can not be saturated if the water curtain pressure is less than a certain value. Water curtain pressure with a certain value gives a strong safe guarantee of saving oil in the underground petroleum storage caverns.

DDARF Analysis on Shear Tests of Jointed Rock Mass

Referring to the previous shearing model tests on intermittence jointed rock mass, DDARF method was adopted to conduct the corresponding numerical simulation. It could be concluded from the cracking failure phenomena that the results of the numerical simulation and the tests were in good agreement. Then the intermittence joints were arranged as en echelon and different cracking failure phenomena, peak shear strengths and strain-stress relationships were also obtained.

The Study on Failure Mechanism of 3D Cracked Rock Mass under Fissure Water Pressure

In this paper, the failure mechanism of rock-like specimens with built-in 3D double cracks under fissure water pressure was numerically investigated. The initiation and propagation process of secondary cracks under fissure water pressure was simulated by using the modified elasto-brittle model and the superfine meshing method in the FLAC3D program. The fluid-solid coupling in cracked rock masses was preliminarily studied. Some of the simulation results are in good agreement with the previous results tested by scholars.