scholarly journals Numerical Simulation of Cracking Failure and Weakening Law of Roadway Surrounding Rock under High Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Feng Cheng ◽  
Ai-jun Chen ◽  
Di Wu ◽  
Xian-yuan Tang ◽  
Chun-hui Su
Keyword(s):  
Numerical Simulation ◽  
Plastic Zone ◽  
Strain Softening ◽  
Water Pressure ◽  
High Stress ◽  
Simulation Method ◽  
High Water ◽  
Hydraulic Head ◽  
Effective Porosity ◽  
Metal Mine

In deep roadway mining, high water pressure causes rock mass cracking and weakens the overall strength, affecting the stability of underground metal mine mining roadways. Therefore, using a numerical simulation method, we analyzed the strain softening characteristics of rocks after the inflexion point of elasticity and studied the strain distribution and the minimum support resistance under high-pressure groundwater conditions. Considering the groundwater pressure and effective porosity on the strain softening characteristics of the surrounding rocks, we investigated the critical groundwater pressure under which the surrounding rocks would remain stable. Actual engineering verification helps to obtain the supporting characteristic curves under different influencing factors. We found that water pressure and effective porosity are the significant factors that decide the development scope of the plastic zone. The more significant the increase of the plastic zone, the more notable the changes in the support curve. Moreover, the plastic zone is likely to occur when the hydraulic head is between 30 and 50 m; when the hydraulic head exceeds 50 m, it is likely to produce a relaxation zone.

scholarly journals Study on Mechanical Characteristics of Segmental Joints of a Large-Diameter Shield Tunnel under Ultrahigh Water Pressure

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8392
Author(s):  
Lei Kou ◽  
Zhihui Xiong ◽  
Hao Cui ◽  
Jinjie Zhao
Keyword(s):  
Numerical Simulation ◽  
Theoretical Calculation ◽  
Water Pressure ◽  
Concrete Strength ◽  
Large Diameter ◽  
Simulation Method ◽  
High Water ◽  
Calculation Model ◽  
Bending Stiffness ◽  
High Water Pressure

At present, there is no clear design standard for segmental joints of large-diameter shield tunnels under high water pressure. In this paper, a theoretical calculation model for the bending stiffness of segmental joints under high water pressure is proposed. The numerical simulation method is used to investigate the failure and crack formation processes of single-layer and double-layer lining segments under large axial forces. The effects of axial force, bolt strength, and concrete strength on the bending stiffness of joints are then studied using a theoretical calculation model of segmental joints. The results show that under extremely high water pressure, the influence of double lining on joint stiffness is limited. It is more rational and safe to compute the bending stiffness of segmental joints using this theoretical model rather than the numerical simulation method. The parameter analysis reveals that increasing the bolt strength has a minor impact on bending stiffness and deformation, whereas increasing the concrete strength has the opposite effect. The influence of ultimate bearing capacity and deformation decreases non-linearly as the axial force increases.

Numerical Simulation of Engineering Wave for Zhongzui Bay

2007 ◽  
Author(s):  
Xiejun Shu ◽  
Senhui Jiang ◽  
Ruijie Li
Keyword(s):  
Numerical Simulation ◽  
Water Level ◽  
Simulation Method ◽  
High Water ◽  
Wave Transformation ◽  
Return Periods ◽  
Engineering Construction ◽  
Wave Refraction ◽  
High Water Level ◽  
Mild Slope Equation

For providing a better shelter condition, it is necessary to build a breakwater in Zhongzui Bay. In order to know whether mooring area meets the requirement after engineering construction and compare the mooring area between solid breakwater and permeable breakwater, a numerical simulation method is used in the sheltering harbor of Zhongzui Bay. The used Mild-slope equation which describes wave refraction, diffraction and reflection, considers the steep slope bottom and effect of energy dissipation. It has been validated to fit for simulating wave transformation in the coastal zone. Under extreme high water level and design high water level, wave fields in the calculation area of three wave types in three different return periods are simulated by using this method respectively. In addition, wave height in front of breakwater can be provided. Then the wave parameters and the mooring area of two occasions, with and without breakwater, are gained in calculation area. Based on these results, some conclusions are presented in the end.

Numerical Simulation for Destroy Pattern of Surrounding Rock of Circle Tunnel with M-H Coupling Action

2011 ◽  
Vol 71-78 ◽  
pp. 3572-3576
Author(s):  
An Nan Jiang ◽  
Peng Li
Keyword(s):  
Numerical Simulation ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rock Fracture ◽  
High Stress ◽  
Surrounding Rock ◽  
Zonal Disintegration ◽  
Affecting Factors ◽  
Tunnel Wall ◽  
Shear Belt

The uniform zonal disintegration of surrounding rock is the peculiar phenomena of deep and high stress field, researching the inner mechanism and affecting factors has important meaning for guaranteeing the safety of deep engineering. The paper adopted strain soft Mohr-Coulomb model and carried out numerical simulation of surrounding rock fracture and excavation. The simulation states that along with the unloading time accumulation, the shear belt produced from tunnel wall and developed to inner rock. The corresponding shear stress concentration zone also spread to inner rock and destroy zone increasing. The pore water pressure increasing will accelerate the shear belt developing and increase the destroy degree.

Analysis of Influences of Weak Joints and Confining Pressure on Rock Mass Strength by Numerical Simulation

2013 ◽  
Vol 438-439 ◽  
pp. 607-611 ◽  
Author(s):  
Da Hai Wang ◽  
Hao Ran Guo ◽  
Hui Zhao ◽  
Yan Wei Guo
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Plastic Zone ◽  
Influencing Factors ◽  
Rock Strength ◽  
Strain Softening ◽  
Confining Pressure ◽  
Plasticity Model ◽  
Rock Mass Strength

Principal influencing factors of the strength of rock mass with weak joints were studied in this paper. Dip angles of weak joints in addition with the confining pressure is studied based on strain-softening/hardening plasticity model. The broken mechanism from the perspective of plastic zone was analyzed. The strength of rock mass with weak joints is mainly under control of the joints occurrence, the joints dip and the rock strength, and great influenced by the confining pressure. A higher strength is obtained with a higher confining pressure, the broken mechanisms varies with different joints dips.

scholarly journals Stress Heterogeneity and Slip Weakening of Faults under Various Stress and Slip

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Longjun Dong ◽  
Qiaomu Luo
Keyword(s):  
Slip Surface ◽  
Water Pressure ◽  
High Stress ◽  
Local Stress ◽  
Seismic Source ◽  
High Water ◽  
Fault Slip ◽  
Underground Engineering ◽  
Finite Element Software ◽  
Stress Heterogeneity

The rock mass of deep underground engineering is in the complex geological environment of high stress, high temperature, and high water pressure. In the process of deep mining and underground space development, the fault-slip seismic source may cause engineering accidents with strong destructive capacity. An in-depth study of fault slip characteristics is very important in the engineering disaster prevention and control. In this paper, a slip model was established based on the finite element software ABAQUS. A total of 20 loading ways are set for various stress and slip, which include the possible slip conditions of fast slip, slow slip, and critical state. By comparing the simulation diagrams and collecting the data of representative grid elements on the loading surface and slip surface, the slip characteristics such as stress heterogeneity under different loads are analyzed. The results show that the increase of slip velocity will make the slip unstable, and the local stress and deformation will become irregular. The spatial stress heterogeneity and the resulting local high working rate will lead to the decrease of the friction strength and the slip weakening. These results can provide some useful suggestions for the research of seismic activities caused by fault slip.

scholarly journals Numerical Simulation Three-Dimensional Nonlinear Seepage in a Pumped-Storage Power Station: Case Study

Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 180 ◽  
Author(s):  
Shaohua Hu ◽  
Xinlong Zhou ◽  
Yi Luo ◽  
Guang Zhang
Keyword(s):  
Numerical Simulation ◽  
Water Pressure ◽  
Flow Theory ◽  
High Water ◽  
Control Measures ◽  
Nonlinear Flow ◽  
Heaviside Function ◽  
Power Station ◽  
Pumped Storage ◽  
High Water Pressure

Due to high water pressure in the concrete reinforced hydraulic tunnels, surrounding rocks are confronted with nonlinear seepage problem in the pumped storage power station. In this study, to conduct nonlinear seepage numerical simulation, a nonlinear seepage numerical model combining the Forchheimer nonlinear flow theory, the discrete variational inequality formulation of Signorini’s type and an adaptive penalized Heaviside function is established. This numerical seepage model is employed to the seepage analysis of the hydraulic tunnel surrounding rocks in the Yangjiang pumped-storage power station, which is the highest water pressure tunnel under construction in China. Moreover, the permeability of the surrounding rocks under high water pressure is determined by high pressure packer test and its approximate analytical model. It is shown that the flow in the surrounding rocks is particularly prone to become nonlinear as a result of the high flow velocities and hydraulic gradients in the nearby of the seepage-control measures and the high permeability fault. The nonlinear flow theory generates smaller flow rate than the Darcy flow theory. With the increase of nonlinear flow, this observation would become more remarkable.

Numerical Simulation on the Influence of the Groundwater Flow Field during Tunnelling

2012 ◽  
Vol 594-597 ◽  
pp. 1230-1233 ◽  
Author(s):  
Xiao Bing Kang ◽  
Xie Wen Hu ◽  
Huai Qian Xie
Keyword(s):  
Numerical Simulation ◽  
Groundwater Flow ◽  
Water Pressure ◽  
High Water ◽  
Tunnel Construction ◽  
Groundwater Environment ◽  
Western Development ◽  
Geological Conditions ◽  
Sphere Of Influence ◽  
The Impact

With the vigorous development of China's economic construction, especially since the western development, needs of traffic tunnel construction are increasing, a large number of tunnels will be built in the mountainous with deeply buried and high water pressure, it is an urgent problem about research on the groundwater environment and the ecological environment in the tunnel site area causes of tunnel construction. The Songpan County Mounigou tunnel located in the high altitude alpine region, regional and environmental geological conditions are complicated, the strata in the tunnel site area is aquifer, and developed faults fractures and fissures, tunnelling will lead to groundwater dewatering and cause the deterioration of the groundwater environment, Then great collapse, burst mud and water gushing will occur during the tunnel construction due to the enrichment of groundwater in tunnel site. Take a research on numerical simulation of groundwater flow in the tunnel site area, the tunnel excavation will form a larger catchment corridor, the impact is bound to the tunnel site hydrogeological conditions in the sphere of influence may appear to lower the groundwater level, seisensui drawdown or part of the dry, provide the basis for tunnel construction.

scholarly journals Influence factors and effect prediction model of the tertiary migrations of remaining oil

2020 ◽  
Author(s):  
Rongda Zhang ◽  
Guanghui Yang ◽  
Kang Ma ◽  
Zhichao Song ◽  
Junjian Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Influence Factors ◽  
Simulation Method ◽  
High Water ◽  
Residual Oil ◽  
Prediction Formula ◽  
Control Factors ◽  
Remaining Oil ◽  
Water Cut ◽  
Surface Analysis Method

Abstract Worldwide, for older fields that are in the late stages of production period, production wells that lose production value due to high water cut are usually shut down. In this situation, the remaining oil in the reservoir will be re-enriched under the influence of gravity differentiation and capillary forces. Production practices find when the production well is closed for a long time and then opened for restarting production, the water cut drops dramatically and the output rise sharply. In order to anticipate the effects of enrichment of remaining oil in the reservoir, this paper analyzes 10 influencing factors respectively. Secondly, change of water cut before and after shut-in is used as the evaluation index of residual oil enrichment effect. Numerical simulation method is used to simulate the influence of different factors on the effect of external migrations of remaining oil at different levels. Grey correlation analysis is utilized to rank the correlation of 10 factors on residual oil enrichment and then we can get the main controlling factors affecting residual oil enrichment. Finally, the response surface analysis method is used to establish a 5-factor 3-level model, and the corresponding prediction results are obtained through numerical simulation experiments. The main control factors are fitted to obtain the prediction formula of the remaining oil enrichment effect. As a result, we can use the prediction formula to forecast the enrichment effect of remaining oil under different reservoir parameters.

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