Surrounding Rock Deformation Control Research Articles

The Collapse Deformation Control of Granite Residual Soil in Tunnel Surrounding Rock: A Case Study

Since it is difficult to control tunnel construction in weak and broken surrounding rock, the large deformation of tunnel surrounding rock has always been a great danger to construction safety. In this study, the characteristics of a tunnel collapse deformation and its causal factors are analysed as an example of a large deformation accident in a tunnel with granite residual soil in the surrounding rock. First, a support vector regression algorithm optimized by the genetic annealing algorithm (GASA-SVR) is used to construct a back-analysis model of the surrounding rock mechanical parameters. Then, based on the field measured data, the surrounding rock mechanical parameters of the tunnel are inverted. Finally, the finite element method is used to simulate different surrounding rock deformation control schemes, and the optimal deformation control measures are obtained. The results show that the simulated annealing algorithm (SA) enhances the local search capability of the genetic algorithm (GA) so that the hyperparameter optimization solution of the support vector regression (SVR) is the global optimal solution. The parameters obtained from the inversion of the GASA-SVR model are simulated in PLAXIS3D within 4.0% of the measured values in the field. With the application of optimized support measures at the site, the deformation of the surrounding rock has been effectively controlled.

Tunnel entrance crossing spoil heap deformations control by micropile combine with coupling beams

Aiming at the deformation control problem of the tunnel entrance crossing the spoil heap at the Xialao junction, this paper adopts the micropile combined with the coupling beams method to treat the spoiled layers. The results show that the excavation of the tunnel after the construction of the micropile and coupling beam will cause vertical deformation of the tunnel and the slope surface. The main reason is that the soil layer structure is loose, and the tunnel excavation causes the whole displacement of the loose body. In addition, the buried depth of the tunnel is shallow, so it cannot form an effective soil arch. The stability process after the construction of the micropile method is the process of stress redistribution, and the rock and soil are gradually compressed and compacted. That is, the construction by the micropile method changes the surrounding rock level of the tunnel and reduces the height of the soil arch. Therefore, it is suggested that the tunnel excavation should be carried out when the micropile is constructed after the soil layers are consolidated completely. The micropile method treats the loose spoiled soil at the tunnel entrance, which saves 73% of the total cost compared with the scheme of directly digging out the accumulation, and the economic benefit is very obvious.

Overburden Deformation Rule in Super High Seam Fully Mechanized Caving Mining of Thick Unconsolidated Stratum

It is urgent for westward coal mine development to control surrounding rock of thick unconsolidated stratum, thin basement rock, and super high seam under geological conditions. Studying surrounding rock deformation control mechanism under special geological conditions in western regions is of practical guiding significance for the implementation of China’s energy strategy in western regions, with special mining geological conditions of the experimental mine as the background, deformation rule, failure characteristic, and stress distribution characteristic of surrounding rock in fully mechanized caving mining of thick unconsolidated stratum. By establishing the structural mechanics model of “sidestepped rock beam,” the stability criterion is determined. The horizontal displacement of surrounding rock in the middle of the working face is small, and the displacement at both ends is large. After the mining of the working face, an “O” ring appears on the main roof. The ring extends outward with the excavation, reaches the maximum at the initial weighting, and its displacement decreases from inside to outside. Finally, through theoretical analysis, experimental research, numerical calculation, and field observation, the thin bedrock and ultra-high coal seam are systematically analyzed, and its deformation and failure mechanism is revealed. Relevant research findings are successfully implemented on the scene and effectively ensured safety, high yield, and high efficiency of the mine.

A Case Study on Surrounding Rock Deformation Control Technology of Gob-Side Coal-Rock Roadway in Inclined Coal Seam of a Mine in Guizhou, China

Surrounding rock deformation control of gob-side coal-rock roadway in inclined coal seams (GCRICS) is a major problem in gob-side entry technology application practice. This paper describes a case study of the surrounding rock deformation characteristics and control technology of a typical GCRICS in Guizhou, China. As according to data obtained during a field investigation, the reasons for the deformation and failure of 151509 tailentry and the shortcomings of the original support scheme were analyzed. In combination with existing theory and field experience, the “anchor cable + U-shaped steel + shotcreting + grouting” (CUSG) support method was proposed. The plastic zone distribution, displacement, and stress evolution law of the roadway-surrounding rock under the four support modes were analyzed and compared by numerical simulation. The results show that the supporting effects of several support methods varied from good to poor; CUSG was the best, followed by anchor cable support, U-shaped steel support, and then no support. Based on the previous seepage grouting theory, a slurry diffusion model of hollow grouted anchor cable (HGC) was established and the calculation formulas of slurry diffusion radius and grouting time were deduced, which provided guidance for field construction. Finally, the CUSG surrounding rock control technology was applied to 151509 tailentry subsequent roadway support. Through drill holes, analysis of the surrounding rock of the non-grouting area and the grouting area was conducted. It was found that the surrounding rock of the grouting area was high in integrity and strong in bearing capacity. Throughout the excavation period to the end of roadway mining, the roadway did not have to be repaired. This case study has high practicability, high popularization value, and provides a useful reference for the engineering support design of the GCRICS.

Study on overburden failure law and surrounding rock deformation control technology of mining through fault.

In the mining process of working face, the additional stress generated by the fault changes the law of roadway deformation and failure as well as the law of overburden failure. Aiming at the influence of the fault in the mining process of working face, this study introduced the geological strength index (GSI) to analyze the stress distribution in the elastic-plastic zone of the surrounding rock of the roadway. And similar experiments under different engineering backgrounds were combined to study the characteristics of overburden movement and stress evolution. Based on the conclusions obtained, the roadway support scheme was designed. This study shows that, compared with ordinary mining, through-the-fault mining causes slippage and dislocation of the fault, the load of the overburden is transferred to both sides of the fault, and the stress near the fault accumulates abnormally. The "three zones" characteristics of the overburden movement disappear, the subsidence pattern is changed from "trapezoid" to "inverted triangle", and the influence distance of the advanced mining stress on the working face is extended from 20m to 30m. The instability range of roadway surrounding rock is exponentially correlated with the rupture degree of the surrounding rock. Through the introduction of GSI, the critical instability range of roadway surrounding rock is deduced to be 2.32m. According to the conclusion, the bolt length and roadway reinforced support length are redesigned. Engineering application shows that the deformation rate of the roadway within 60 days is controlled below 0.1~0.5mm/d, the deformation amount is controlled within 150mm, and the roadway deformation is controlled, which generally meets the requirements of use. The research results provide guidance and reference for similar roadway support.

Research of the Surrounding Rock Deformation Control Technology in Roadway under Multiple Excavations and Mining

To effectively control the large surrounding rock deformation of the mining roadway under multiple excavations and mining in Wangcun coal mine, the field investigation, numerical simulation, field test, and monitoring were conducted, and the characteristics of stress and deformation evolution of the surrounding rock under the influence of multiple excavations and mining were analyzed; then the collaborative supporting technology of high prestressed bolt and short anchor cables was proposed in this study. The results show the following: (1) under the influence of multiple excavations and mining, the peak vertical stress of the typical air-return roadway reaches 23 MPa, and the deformation increases by about 2.8 times after the mining of adjacent panel. (2) The principle of the roadway support under the influence of multiple excavations and mining in Wangcun coal mine is determined; from the perspective of prestress, we can conclude that the active support of short anchor cables is better than that of long anchor cables. (3) Based on the results of the field monitoring, the bolt stress can be divided into four stages: the loss stage of prestress, the sudden-decrease stage of the roof periodic weighting, the decrease stage of advanced support, and the rapid-increase stage of strong disturbance. Due to the large anchorage range of anchor cables, there is no decrease stage of advanced support. After the application of prestress, the bolt stress of side bolts and top bolts decreases, and the reduction amplitude is up to 30 kN. (4) As the panel advances, the deformation of the surrounding roadway increases, and the growth rate is also increasing gradually. However, the final displacement of the roof, floor, and two sides is within 18 mm. The bolt and anchor cables are not broken, and the control effect is good. The research results have a certain reference value for similar roadway control.

Exploring the deformation features and control techniques for surrounding rock of slate section tunnel

To improve the safety of tunnel engineering, this study explores the mechanical deformation features and the support parameters of the tunnel. First, the uniaxial and triaxial compression tests are applied to study the mechanical features of slate under dry conditions and different water-containing conditions. Under different construction methods, the relationship between surrounding rock deformation and the time is analyzed. Second, the support vector machine (SVM) algorithm and particle swarm optimization (PSO) algorithm to predict the deformation trend of the surrounding rock of the slate section tunnel. Finally, for the stability control of the surrounding rock of the tunnel and the safety of the supporting structure, the convergence-constraint method is utilized for the deformation control of the surrounding rock of the slate section tunnel. The results show that the uniaxial and triaxial compression tests obtain that the compressive strength of slate will decrease with the increase of the water content of the rock mass. The use of the SVM algorithm combined with the PSO algorithm can improve the rate and accuracy of surrounding rock deformation prediction. The relationship between the surrounding rock features and the support features under different support structures is obtained. It is found that the surrounding rock supporting structure is optimal when the primary support is 75%, the thickness of the shotcrete is 35 cm, the thickness of the second lining is 96%, and the thickness of the second lining is 50 cm. By using these methods, the prediction performance of surrounding rock deformation features is improved, and the proposed surrounding rock deformation control techniques improve the safety of tunnel engineering.

特大断面浅埋隧道围岩变形控制技术研究

特大断面浅埋隧道围岩变形控制技术研究

Hole enlarging anchorage technology of surrounding rock of roadway in weakly consolidated formation

Aiming at the problem of surrounding rock deformation control of the roadway in weakly consolidated formation and combined with the calculation method of anchoring force of anchor bolt, this paper analyzes the feasibility of hole enlarging and anchoring and proposes a calculation method for the anchoring force of hole enlarging and anchoring; this paper establishes a simplified mechanics model of cylinder table enlarging, standing circular table enlarging and circular table enlarging with the method of theoretical mechanics and material mechanics and finds after analysis that the anchoring effect is best when the angle between the busbar and the axis of the circular table is θ < 45°. It draws a two-variable function relation curve for the surrounding rock stress σb and the hole enlarging parameters at the supporting region of the enlarged part of the standing circular table and obtains the optimal anchor length L is 130 mm, the optimal hole enlarging angle θ is 15°, and the optimal hole diameter D is 100 mm. It verifies the theoretical analysis results with numerical calculation, and the results show that the theoretical derivation is consistent with the simulation results. The research results make up the inadequacies of the accurate calculation method for the optimal hole enlarging parameters of the surrounding rock hole of roadway in the weakly consolidated formation, and provide a theoretical basis for the popularization and application of the anchoring technology in the roadway support of weakly consolidated formation.

Mechanical behaviour analysis and support system field experiment of confined concrete arches

Soft rock control is a big challenge in underground engineering. As for this problem, a high-strength support technique of confined concrete (CC) arches is proposed and studied in this paper. Based on full-scale mechanical test system of arch, research is made on the failure mechanism and mechanical properties of CC arch. Then, a mechanical calculation model of circular section is established for the arches with arbitrary section and unequal rigidity; a calculation formula is deduced for the internal force of the arch; an analysis is made on the influence of different factors on the internal force of the arch; and a calculation formula is got for the bearing capacity of CC arch through the strength criterion of bearing capacity. With numerical calculation and laboratory experiment, the ultimate bearing capacity and internal force distribution is analyzed for CC arches. The research results show that: 1) CC arch is 2.31 times higher in strength than the U-shaped steel arch and has better stability; 2) The key damage position of the arch is the two sides; 3) Theoretical analysis, numerical calculation and laboratory experiment have good consistency in the internal force distribution, bearing capacity, and deformation and failure modes of the arch. All of that verifies the correctness of the theoretical calculation. Based on the above results, a field experiment is carried out in Liangjia Mine. Compared with the U-shaped steel arch support, CC arch support is more effective in surrounding rock deformation control. The research results can provide a basis for the design of CC arch support in underground engineering.

Surrounding rock deformation control of asymmetrical roadway in deep three-soft coal seam: a case study

Surrounding rock deformation control of asymmetrical roadway in deep three-soft coal seam: a case study

Application of Distributed Optical Fiber Sensing Technology in Surrounding Rock Deformation Control of TBM-Excavated Coal Mine Roadway

After roadway excavation, the deformation and failure of roadway surrounding rocks typically results in roadway damage or collapse. Conventional monitoring techniques, such as extensometers, stress meters, and convergence stations, are only capable to detect the stress or strain data with the shallow layers of surrounding rocks, and they require arduous manual works. Moreover, in the abovementioned monitoring techniques, the monitoring instruments are installed behind the excavation face; therefore, the strain and deformation occurring in front of excavation face cannot be detected. In order to eliminate these shortcomings, an innovative monitoring system for surrounding rock deformation control has been developed base on Brillouin optical time domain reflectometry. Compared with conventional monitoring systems, the proposed system provides a reliable, accurate, and real-time monitoring measure for roadway surrounding rock deformation control over wide extension. The optical fiber sensors are installed in boreholes which are situated ahead of the excavation face; therefore, the sensors can be protected well and the surrounding rock deformation behaviors can be studied. The proposed system has been applied within a TBM-excavated roadway in Zhangji coal mine, China. The surrounding rock deformation behaviors have been detected accurately, and the monitoring results provided essential references for surrounding rock deformation control works.

Analysis of the Engineering Geology and Deformation Control in Highway Tunnel

The tunnel engineering geology and deformation control is one key of the basis for the tunnel engineering construction and operation management and safety technology security. However, it is becoming one of the bottleneck problems for underground tunnel construction project information to be solved accurately and fast to assess the stability of surrounding rock because of the special environment in the tunnel construction and acquiring the deformation information of surrounding rock. Relying on the geology analysis and the surrounding rock deformation control of research work on the ZIJING mountain tunnel in DAGUANGNAN highway in HUBEI province of Chinese, it is investigated to combine the geological information with field monitoring organically which is in order to determine the possible geological damage during tunnel construction. Then, based on the monitoring data processing and analysis, the deformation control standard of the tunnel geological disaster area is putted forward. Those research works are providing important reference basis for similar projects.

Tunnel Surrounding Rock Deformation Characteristics and Control in Deep Coal Mining

In order to study the failure characteristics and control method of deep tunnel surrounding rock, based on the stress test, the structure and stress state of the main transportation tunnel surrounding rock in Mine Zhaogezhuang level 14 was analyzed, and it shows that the surrounding rock is exposed to an interphase hard and soft disadvantageous structure state and complex high stress repeated addition area; Through the theoretical analysis and the statistical data, the relation between the tunnel stress transformation and the surrounding rock deformation was proposed; Through the numerical simulation of the tunnel surrounding rock failure process with the help of RFPA procedure, the results show that the damage of the transportation tunnel level 14 mainly occurs in the bottom and the two coal ribs, and the failure process is spreading from the bottom to the two coal ribs, and the effect of the surrounding rock deformation control is obvious by using the way of 2.5 m anchor with 1.0 m grouting strengthening.

Study of Soft Rock Roadway Support Technique

Soft rock prevalent in coal-bearing strata in China, a lot of soft rock is buried deep in the larger role of high stress by the formation, and maintenance of the roadway is very difficult to dig. Therefore, the soft rock tunnel in the control theory and practice of in-depth study on the maintenance of soft rock and coal mine production safety have important theoretical and practical engineering value. Based on the characteristics of soft rock roadway analysis, and theory and method of supporting the research, choose the right type of support and supporting means, surrounding rock deformation control, reduce destruction of surrounding rock strata behavior, to take reasonable supporting effective technical control of roadway deformation and maintain the stability of surrounding rock. On the roadway approach to the design support for soft rock tunnel problems, combined with the practical application of steel mesh and anchor design support system anchorage system and deep surrounding rock formation deep control system, calculation of parameters of rational support And the corresponding recommendations and measures, and achieved good results.