Optimization Of Support Parameters Research Articles

Research on the Support Parameters Optimization of Large Section Roadway in Shallow Coal Seam

Research on the Support Parameters Optimization of Large Section Roadway in Shallow Coal Seam

Heterogeneity identification method for surrounding rock of large-section rock tunnel faces based on support vector machine

PurposeThe purpose of the study is to quickly identify significant heterogeneity of surrounding rock of tunnel face that generally occurs during the construction of large-section rock tunnels of high-speed railways.Design/methodology/approachRelying on the support vector machine (SVM)-based classification model, the nominal classification of blastholes and nominal zoning and classification terms were used to demonstrate the heterogeneity identification method for the surrounding rock of tunnel face, and the identification calculation was carried out for the five test tunnels. Then, the suggestions for local optimization of the support structures of large-section rock tunnels were put forward.FindingsThe results show that compared with the two classification models based on neural networks, the SVM-based classification model has a higher classification accuracy when the sample size is small, and the average accuracy can reach 87.9%. After the samples are replaced, the SVM-based classification model can still reach the same accuracy, whose generalization ability is stronger.Originality/valueBy applying the identification method described in this paper, the significant heterogeneity characteristics of the surrounding rock in the process of two times of blasting were identified, and the identification results are basically consistent with the actual situation of the tunnel face at the end of blasting, and can provide a basis for local optimization of support parameters.

Study on the Optimization of Support Parameters of Metro Station Constructed by Arch Cover Method

Study on the Optimization of Support Parameters of Metro Station Constructed by Arch Cover Method

Analysis of mining roadway with large deformation of broken soft coal and research on supporting technology: A case study in Xin’an coal mine, China

The safe mining of Xin'an Coal Mine was challenging because of several problems, including the soft roadway seams, fracture development, fracturing and deformation of the incompact surrounding rock, and the unreasonable support parameters. Through the investigation of these problems and the analysis of the influence of active and passive support on the stability of the roadway combined with the theory, we proposed a new support plan and conducted field tests. The obtained results were as follows: broken surrounding rock, low degradation strength, unreasonable support parameters, and uncoupling of support and surrounding rock were the main causes of roadway deformation. To a certain extent, the passive support could prevent the damage of the surrounding rock, prevent the attenuation of the stress of the rock around the anchor point, and enhance the effect of active support. The active support could pre-support the gravity of the broken surrounding rock, improve the stress environment of the surrounding rock, and increase the self-balancing ability of the surrounding rock structure. It also could control the damage zone of surrounding rock and the expansion of the stress arch to the depth, restrict the range of rock strata that the passive support system needed to control, and play a protective role. The active–passive coupling support scheme had an amplifying effect. In this regard, the active–passive coupling support scheme of “bolt, W steel belt” + “anchor cable, anchor cable beam” + “I-steel shed” was practiced, and the relevant support parameters were determined. The scheme was implemented in the 2301 mining roadway, and the displacement convergence deformation of the two walls and the roof and floor of the roadway was monitored. It was found that the deformation of the roadway surrounding rock was effectively controlled and the scheme could ensure the stability of the roadway. The research results could provide a basis for the stability analysis of large deformation of broken soft coal of mining roadway and also a basis for the optimization of support parameters.

GPR‐MCS model of reliability analysis of key blocks and its engineering application

AbstractReasonable rock bolting schemes for potentially unstable blocks should be proposed and optimized in order to prevent rockfall hazard during tunnel construction. However, the reliability index of key block caused by uncertainty of geometric and mechanics parameters is not easy to be obtained by numerical simulation. Since the performance function of stability analysis of supporting key block is too complex, it is also difficult to calculate the reliability by using analytical and graphic methods rapidly. In this paper, the Gaussian process regression (GPR) model was established instead of the explicit function of key block. The safety factor of supporting key block calculated by UnWedge procedure was taken as the sample output of response model. With the GPR model coupling Monte Carlo Simulation (GPR‐MCS), the failure probability of key block could be predicted rapidly. The reliability of key block with different supporting schemes were analyzed, and the optimization of support parameters for key block was also carried out. It has direct meaning to prevention and control of dangerous key block during tunnel construction.

Research on Surrounding Rock Control Technology of Dongbaowei Deep Mining Roadway

In order to explore the stability control of surrounding rock in the process of deep mining, comparative analysis of stress, deformation, and fracture characteristics of surrounding rock of deep and shallow mining roadway in dongbaotou coal mine, laboratory experiments, field measurement, numerical simulation, and field industrial experiments were adopted to put forward the control plan of the surrounding rock in deep roadway, which were verified by field industrial experiments. The results of laboratory experiments and field experiments show that the mechanical properties of deep roadway surrounding rock of Dongbaowei Coal Mine are significantly lower than those of the shadow roadway, mainly due to the development of joints and fractures of the overlying strata in the deep stope, serious impact on the disturbance of the roadway which has been made by the strong pressure of the stope, and reduced crushing strength of surrounding rock. Through comparative analysis of deep roadway support plan carried out by numerical simulation, the support scheme suitable for Dongbaowei Coal Mine is put forward, which is applied in the field. Field industrial experiments show that after the optimization of support parameters, the deformation of surrounding rock of roadway is well controlled. The displacement of surrounding rock of roadway is basically stable after 10∼15 days. The support of surrounding rock of roadway has good effect, which achieves the goal of stability control of deep roadway surrounding rock.

Optimization of combined support in soft-rock roadway

Ground support and reinforcement technology can greatly enhance the stability of underground excavations and make the underground infrastructure safer. This paper investigates a combined support methodology aiming at increasing the stability and safety of soft-rock roadways in the Zhongguan iron mine in China via analysis of the field structure of weak surrounding rock by means of numerical modelling, orthogonal experiments, field observations and optimization of combined support parameters. A test scheme design for the underground metal mine roadway support was constructed to study the mechanisms of large deformations of roadway surrounding rock and the influencing factors of the side displacement, roof subsidence, and plastic zone volume were quantitatively analyzed. The optimization of support parameters was carried out in combination with numerical simulations and orthogonal tests. Modelling and field test results show that the support effect of the optimized scheme has greatly improved the roadway stability and the combined method controls much more effectively the large deformation of the broken rock mass as well as the support function of the excavation roadway. The proposed combined support method can provide a support design reference for similar projects in similar rock masses.

Mechanical and Deformation Characteristics and Optimization of Support Parameters for Superlarge‐Span Tunnel: A Case Study from Laohushan Tunnel

In the new construction or reconstruction of expressway projects, the number of highway twin tunnels with eight lanes is increasing. However, there are no corresponding design support parameters and measures in the current technical specifications for tunnel design and construction in China. In Laohushan superlarge‐span highway tunnel with single hole and four lanes, the deformation behavior and mechanical characteristics of support structures are measured and analyzed. The monitoring results indicated that the deformation of tunnel structure mainly experienced three stages: rapid deformation, slow deformation, and stable deformation, and finally reached a relatively stable state; the structure stress of primary support and secondary lining increases sharply at first and then tends to be stable gradually with the gradual construction of each excavation part in the tunnel; the stress of each measuring point at the steel rib is less than the yield limit of steel rib (235 MPa), and the support structure is safe and stable in the process of tunnel construction. Then, the structure safety of primary support under different support parameters is simulated and calculated by numerical simulation with Grade IV rock mass, and the reasonable support parameters for Laohushan highway tunnel are studied considering the structural safety and engineering economy. It is suggested to use the H175‐type steel sets with a distance of 80 cm and C25 shotcrete with a thickness of 26 cm. The results could provide reference for similar tunnel projects and provide a basis for the design specification and construction standards for superlarge‐span tunnels.

Support parameters optimization and engineering application of roadway with broken-expand surrounding rock in deep

Support parameters optimization and engineering application of roadway with broken-expand surrounding rock in deep

Numerical Analysis on Loading History Correlation for Large Deformation Control within Deep Soft Rock

The correlation of the load history in the nonlinear large deformation mechanical design method is discussed. Then the different schemes of support construction process which are used to control the nonlinear large deformation of the east wing main haulage roadway in -1000m level of a certain coal mine are simulated by the program of 3D finite difference. The results show that the deformation results, the displacement distribution characteristics and the stress concentration degree of surrounding rock are significantly different due to the different construction sequence. After plastic large deformation occurs in deep soft rock ,the mechanical response characteristics of the surrounding rock closely related to the entire loading history. And different construction sequence will produce different deformation control effect. Therefore, the use of large deformation mechanical design method for the supporting design of deep soft rock is necessary, then based on the proposing of the mechanical countermeasures the best construction process is determined, and the optimization of support parameters must be for this process.

Tunnel Support Parameters Optimization Based on Micro-Seismic Monitoring

The monitoring is important to keep tunnel engineering construction stability. But, regular monitoring means cannot detect the position of the rock which has much stress accurately, accordingly, cannot monitor the influence of the construction process. In order to detect the local surrounding rock cracking due to excavation, a new method named micro-seismic monitoring is proposed to identify the elastic wave of rock bursting. Micro-seismic monitoring technology can find the bursting position by use the elastic wave of the rock, then, it can make an evaluation about the stability of the rock. In the method, using several sensors monitoring data of elastic wave identifies the bursting location. Then, the stability of the rock is analyzed and tunnel support parameters are optimized. At last, the method is used to monitor the Yuanyanghui tunnel located in Shanxi Province, China. The monitoring results identified the relatively stable and relatively unstable area. In-situ measurements on the surrounding rock have been used in the two areas, and therefore we use the analysis results to improve the initial tunnel support parameters.

New development of sets equipment technologies for coal mine long-wall face in China

Background of the development and achievement on sets equipment technologies for coal mine longwall face in China was reviewed initially. On the theoretical side, a coupling model of hydraulic support and surrounding rock, support parameters optimization and three-dimensional (3D) dynamic design method were presented. On the practical side, this paper outlined some of practical issues and discussed some relative methods and technologies. In thin seam coal longwall mining, how to lower equipment height is the first problem that should be solved. Roof pressure regularity, control of roof-fall and collapse, and hydraulic support stability were investigated preferentially in 5∼7 m coal seam longwall mining. The application of equipment for longwall mining with 5∼7 m cutting height in China was concluded. The characteristics of full-mechanized top coal caving for extra thick seam coal were presented. The automation of top-caving hydraulic support and relevant equipment have achieved important breakthrough. At the end of this paper, further development of China’s coal industry and longwall mining technologies and equipment were prospected in brief. This paper gives readers a comprehensive understanding of China’s coal mine longwall face equipment technologies. It will give help to other countries on its coal mining development.

ChemInform Abstract: Reactions of Aldehydes with Diethylzinc Catalyzed by Polymer‐Supported Ephedrine and Camphor Derivatives: Comparisons of Enantiomeric Excesses Achieved with Various Supports: Optimization of Support Parameters to Enable High Enantiomeric Excesses to Be Obtained.

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