深部巷道围岩变形试验与数值模拟研究

为了研究深部软岩巷道的变形破坏特性,以淮南矿区某煤矿13-1煤回采巷道为例,在现场调查回采巷道工程概况的基础上,开展了室内深部回采巷道围岩变形特性相似模拟试验,并基于块体离散元法,建立了深部回采巷道围岩的数值模型,模拟了开挖过程中围岩的变形特性。相似模拟试验和数值模拟试验结果表明,深部巷道围岩的典型特征为:巷道底臌量两帮移近量顶板下沉量,巷道不同围岩受开挖扰动的位移影响范围不同,底板为3.5 m,顶板为2.45 m,两帮为5.5 m。     

Influence of dynamic pressure on deep underground soft rock roadway support and its application

Due to high ground stress and mining disturbance, the deformation and failure of deep soft rock roadway is serious, and invalidation of the anchor net-anchor cable supporting structure occurs. The failure characteristics of roadways revealed with the help of the ground pressure monitoring. Theoretical analysis was adopted to analyze the influence of mining disturbance on stress distribution in surrounding rock,and the change of stress was also calculated. Considering the change of stress in surrounding rock of bottom extraction roadway, the displacement, plastic zone and distribution law of principal stress difference under different support schemes were studied by means of FLAC3D. The supporting scheme of U-shaped steel was proposed for bottom extraction roadway that underwent mining disturbance. We carried out a similarity model test to verify the effect of support in dynamic pressure. Monitoring results demonstrated the change rules of deformation and stress of surrounding rock in different supporting schemes. The supporting scheme of U-shaped steel had an effective control on deformation of surrounding rock. The scheme was successfully applied in underground engineering practice, and achieved good technical and economic benefits.     

Numerical simulation study of the failure evolution process and failure mode of surrounding rock in deep soft rock roadways

Based on the safety coefficient method,which assigns rock failure criteria to calculate the rock mass unit,the safety coefficient contour of surrounding rock is plotted to judge the distribution form of the fractured zone in the roadway.This will provide the basis numerical simulation to calculate the surrounding rock fractured zone in a roadway.Using the single factor and multi-factor orthogonal test method,the evolution law of roadway surrounding rock displacements,plastic zone and stress distribution under different conditions is studied.It reveals the roadway surrounding rock burst evolution process,and obtains five kinds of failure modes in deep soft rock roadway.Using the fuzzy mathematics clustering analysis method,the deep soft surrounding rock failure model in Zhujixi mine can be classified and patterns recognized.Compared to the identification results and the results detected by geological radar of surrounding rock loose circle,the reliability of the results of the pattern recognition is verified and lays the foundations for the support design of deep soft rock roadways.     

深部开采软岩巷道耦合支护数值模拟研究

通过对深部开采软岩巷道的变形破坏机理的研究发现，巷道变形破坏主要是由于支护体力学特性与围岩力学特性在强度、刚度以及结构上出现不耦合所造成的；且变形首先从关键部位开始，进而导致整个支护系统的失稳．因此，要保证深部软岩巷道围岩的稳定性．必须实现支护体与围岩的耦合．数值模拟研究表明，当锚杆与围岩在刚度上实现耦合时，能最大限度地发挥锚杆对围岩的加固作用；当锚网与围岩在强度上实现耦合时，将会使围岩的应力场和位移场趋于均匀化；当锚索与围岩在结构上耦合时，可以充分利用深部围岩强度来实现对浅部围岩的支护．实践证明，软岩巷道耦合支护可以有效解决深部开采软岩巷道支护问题。     

Deformation characteristics of surrounding rock of broken and soft rock roadway

A similar material model and a numerical simulation were constructed and are described herein. The deformation and failure of surrounding rock of broken and soft roadway are studied by using these models. The deformation of the roof and floor, the relative deformation of the two sides and the deformation of the deep surrounding rock are predicted using the model. Measurements in a working mine are compared to the results of the models. The results show that the surrounding rock shows clear rheological features under high stress conditions. Deformation is unequally distributed across the whole section. The surrounding rock exhibited three deformation stages: displacement caused by stress concentration, rheological displacement after the digging effects had stabilized and displacement caused by supporting pressure of the roadway. Floor heave was serious, accounting for 65% of the total deformation of the roof and floor. Floor heave is the main reason for failure of the surrounding rock. The reasons for deformation of the surrounding rock are discussed based on the similar material and numerical simulations.     

Deformation mechanism and excavation process of large span intersection within deep soft rock roadway

The FLAC3D software was used to simulate and analyze numerically the displacement, stress and plastic zone distribution characteristics of a large span intersection in a deep soft rock roadway after the surrounding rock was excavated. Our simulation results show that there are two kinds of dominating factors affecting roadway stability at points of intersection, one is the angle between horizontal stress and axial direction of the roadway and the other are the angles at the points of intersection. These results are based on a study we carried out as follows: first, we analyzed the failure mechanism of a large span intersection and then we built a mechanical model of a rock pillar at one of the points of intersection. At the end of this analysis, we obtained the failure characteristics of the critical parts on the large span intersection. Given these failure characteristics, we proposed a new supporting method, i.e., a Double-Bolt Control Technology (DBCT). By way of numerical simulation, DBCT can effectively control the deformation of the surrounding rock at the points of intersection in roadways.     

Failure mechanism and control technology of water-immersed roadway in high-stress and soft rock in a deep mine

Aiming at soft rock ground support issues under conditions of high stress and long-term water immersion, the ground failure mechanism is revealed by taking the deep-water sumps of Jiulong Mine as the engineering background and employing field investigation, tests of rock structure, mechanical properties and mineral composition. The main factors leading to the surrounding rock failure include the high and complex stress state of the water sumps, high-clay content and water-weakened rock, and the unreasonable support design. In this paper, the broken and fractured rock mass near roadway opening is considered as ground small-structure, and deep stable rock mass as ground large-structure. A support technology focusing on cutting off the water, strengthening the small structure of the rock and transferring the large structure of the rock is proposed. The proposed support technology of interconnecting the large and small structures, based on high-strength bolts, high-stiffness shotcrete layer plugging water,strengthening the small structure with deep-hole grouting and shallow-hole grouting, highpretensioned cables tensioned twice to make the large and small structures bearing the pressure evenly,channel-steel and high-pretensioned cables are used to control floor heave. The numerical simulation and field test show that this support system can control the rock deformation of the water sumps and provide technical support to similar roadway support designs.     

膨胀特性对软岩巷道围岩变形规律的影响研究

针对软岩巷道的特点,利用泥灰岩三轴试验结果,分析了膨胀特性对深井软岩巷道围岩稳定性的影响;利用最新的弹塑性理论研究成果,推导出了膨胀角与围岩变形的直接关系式;采用数值力学的研究方法,分析了软岩巷道周围体积膨胀与扩容现象.数值模拟结果表明:软岩巷道表面变形和巷道周边体积应变随膨胀角的变化均成非线性递增,膨胀角愈大,软岩巷道的围岩条件愈差,巷道周边围压越大,所需要的支护力就越大,这些重要结论为深井条件下软岩巷道工程提供参考.     

膨胀特性对软岩巷道围岩变形规律的影响研究

针对软岩巷道的特点，利用泥灰岩三轴试验结果，分析了膨胀特性对深井软岩巷道围岩稳定性的影响；利用最新的弹塑性理论研究成果。推导出了膨胀角与围岩变形的直接关系式；采用数值力学的研究方法，分析了软岩巷道周围体积膨胀与扩容现象．数值模拟结果表明：软岩巷道表面变形和巷道周边体积应变随膨胀角的变化均成非线性递增，膨胀角愈大，软岩巷道的围岩条件愈差，巷道周边围压越大，所需要的支护力就越大。这些重要结论为深井条件下软岩巷道工程提供参考．     

三软综放沿空锚网索支护巷道回采期间围岩变形特征

针对三软综放沿空巷道围岩大变形、难支护的特点,提出采用锚网索支护新技术,通过对试验巷道数值模拟以及表面位移、围岩深部位移和围岩应力的现场监测,分析了试验巷道矿压显现活动规律,掌握了试验巷道在锚网索支护下的围岩变形规律,这为锚网索支护在三软煤层巷道的推广应用和支护参数设计提供了科学依据.     

Deformation control of asymmetric floor heave in a deep rock roadway: A case study

In order to control asymmetric floor heave in deep rock roadways and deformation around the surrounding rock mass after excavation, in this paper we discuss the failure mechanism and coupling control countermeasures using the finite difference method (FLAC^3D) combined with comparative analysis and typical engineering application at Xingcun coal mine. It is indicated by the analysis that the simple symmetric support systems used in the past led to destruction of the deep rock roadway from the key zone and resulted in the deformation of asymmetric floor heave in the roadway. Suitable reinforced support countermeasures are proposed to reduce the deformation of the floor heave and the potential risk during mining. The application shows that the present support technology can be used to better environmental conditions. The countermeasures of asymmetric coupling support can not only effectively reduce the discrepancy deformation at the key area of the surrounding rock mass, but also effectively control floor heave, which helps realize the integration of support and maintain the stability of the deep rock roadways at Xingcun coal mine.     

Failure laws of narrow pillar and asymmetric control technique of gob-side entry driving in island coal face

In allusion to the problems of complex stress distribution in the surrounding rock and deformation failure laws, as well as the difficulty in roadway supporting of the gob-side entry driving in the island coal face, 2107 face in Chengjiao Colliery is researched as an engineering case. Through physical mechanical test of rock, theoretical and numerical simulation analyses of rock, the analysis model of the roadway overlying strata structure was established, and its parameters quantified. To reveal the deformation law of the surrounding rock, the stability of the overlying strata structure was studied before, during and after the roadway driving. According to the field conditions, the stress distribution in coal pillar was quantified, and the surrounding rock deformation feature studied with different widths of the pillars in gob-side entry driving. Finally, the pillar width of 4 m was considered as the most reasonable. The research results show that there is great difference in support conditions among roadway roof, entity coal side and narrow pillar side. Besides, the asymmetric control technique for support of the surrounding rock was proposed. The asymmetric control technique was proved to be reasonable by field monitoring, support by bolt-net, steel ladder and steel wire truss used in narrow pillar side.     

Deformation and failure characteristics of anchorage structure of surrounding rock in deep roadway

This paper investigated the stress evolution, displacement field, local deformation and its overall distribution, and failure characteristics of the anchorage structure of surrounding rock with different rockbolt spacing through the model experiments. The influences of the pre-tightening force and spacing of rockbolt on the support strength of the anchorage structure of surrounding rock were analyzed by the simulation using FLAC3D numerical software. The support scheme of the excavated roadway was then designed, and the effectiveness of this support scheme was further verified by the displacement measurement of the roadway. The results showed that the maximum displacement between the roof and floor of the west wing track roadway in Kouzidong coal mine, China is about 42 mm, and the maximum displacement between its both sides is about 72 mm, indicating that the support scheme proposed in this study can ensure the stability and safety of the excavated roadway.     

Roadway deformation during riding mining in soft rock

“Riding mining” is a form of mining where the working face is located above the roadway and advances parallel to it. Riding mining in deep soft rock creates a particular set of problems in the roadway that include high stresses, large deformations, and support difficulties. Herein we describe a study of the rock deformation mechanism of a roadway as observed during riding mining in deep soft rock. Theoretical analysis, numerical simulations, and on site monitoring were used to examine this problem. The stress in the rock and the visco-elastic behavior of the rock are considered. Real time data, recorded over a period of 240 days, were taken from a 750 transportation roadway. Stress distributions in the rock surrounding the roadway were studied by comparing simulations to observations from the mine. The rock stress shows dynamic behavior as the working face advances. The pressure increases and then drops after peaking as the face advances. Both elastic and plastic deformation of the surrounding rock occurs. Plastic deformation provides a mechanism by which stress in the rock relaxes due to material flow. A way to rehabilitate the roadway is suggested that will help ensure mine safety.     

Wide pillar roadway retained in the deep high gas coal seam

According to the geological and mining conditions of deep high gas coal seam, this paper established the mechanical model of stope surrounding rock, and analyzed the stress distribution and deformation failure mechanism of working face and coal pillar. The research determined the arrangement mode that adjacent working faces retain wide pillar, and the reasonable support method of roadway that the combined support of roof and grouting combined together. The reasonable time of reinforced roadway was determined. Through analyzing the mechanical model of the ways of roadway supporting, this research drew the conclusions as follows: the combined support of roof and working slope improved the support strength and range of surrounding rock, optimized the support by adjusting the angle of anchor, and reached the support requirements by using cement grouting in working slope and chemical grout in roof. The technology was applied in 15104 working face of Baoan Mine, and obtained good results.     

Deformation mechanism of roadways in deep soft rock at Hegang Xing’an Coal Mine

Engineering geomechanics characteristics of roadways in deep soft rock at Hegang Xing’an Coal Mine were studied and the nature of clay minerals of roadway surrounding rock was analyzed. This paper is to solve the technical problems of high stress and the difficulty in supporting the coal mine, and provide a rule for the support design. Results show that mechanical deformation mechanisms of deep soft rock roadway at Xing’an Coal Mine is of I_ABII_ABCIII_ABCD type, consisting of molecular water absorption (the I_AB-type), the tectonic stress type + gravity deformation type + hydraulic type (the II_ABC-type), and the III_ABCD-type with fault, weak intercalation and bedding formation. According to the compound mechanical deformation mechanisms, the corresponding mechanical control measures and conversion technologies were proposed, and these technologies have been successfully applied in roadway supporting practice in deep soft rock at Xing’an Coal Mine with good effect. Xing’an Coal Mine has the deepest burial depth in China, with its overburden ranging from Mesozoic Jurassic coal-forming to now. The results of the research can be used as guidance in the design of roadway support in soft rock.     

构造应力区巷道变形破坏特征及控制技术研究

水平构造应力对巷道围岩稳定有重要的影响,针对鹤壁九矿东总回风巷在锚网索喷＋u型钢支护难以保证巷道稳定的情况,通过相似材料模拟试验研究不同水平应力作用下锚注支护巷道围岩变形破坏和位移变化特征．试验表明,随着水平应力的增大,底板加强后,水平应力对顶板的作用明显,当水平载荷达到49MPa时有少量浆皮脱落,左肩部出现块状冒落,底板比较稳定,没有发生明显臌起,只出现少量横向裂隙,锚注支护结构能控制围岩变形．将试验结果在现场应用后,通过矿压观测,两帮的最大移近量为144mm,顶底板最大移近量为105mm,锚注支护提高了围岩的自承能力,能够维持巷道稳定,为类似地质条件下的巷道支护提供借鉴．     

Numerical simulation of creep characteristics of soft roadway with bolt-grouting support

Based on the engineering background of a soft rock roadway in Qinan Coal Mine 82 Area,Huaibei Mining Group,three creep models with different support patterns in soft rock roadway were established by using geotechnical software of FLAC2D.According to the calculation results of different models,the change law of mechanical properties with the time of bolt-grouting support structure was obtained.Furthermore,for the test bolt-grouting support roadway,the deformation law of surrounding rock got by underground industrial experiment and field observation accords with the creep law got by numerical calculation.The results of numerical calculation and field observation show that,compared with other supports,the creep of bolt-grouting support roadway enters the steady-state creep stage from tertiary creep stage ahead,the deformations of roof,floor and two sides are decreased greatly,the plastically deforming area in surrounding rock is reduced obviously,and the distribution ranges of maximum and minimum principal stress are shrank obviously.All those fully show that the bolt-grouting support has its remarkable advantages in controlling surrounding rock creep and improving the whole strength of surrounding rock and self-bearing capacity.     

软弱破碎围岩隧道大变形施工力学行为及支护对策研究

围岩大变形是一种常见的、危害极大的施工地质灾害,为了减弱乃至消除此类灾害对工程的影响,首先,基于工程地质条件和地应力测试结果分析,揭示了典型地段软岩挤压大变形的成因;其次,采用有限差分程序研究了软岩段施工过程中围岩的受力和变形特征,分析了支护结构对围岩稳定性的影响,考虑支护有效抑制了围岩变形,将开挖造成围岩变形的影响范围由2倍洞径减至1倍洞径,较好地稳固了掌子面的挤压变形;最后,根据考虑支护的施工过程模拟结果分析,提出了该段软岩大变形控制措施及其变形过大造成侵限的具体处理对策,经开挖后监测数据验证,措施有效,确保了软弱破碎围岩隧道的顺利施工,对类似工程具有一定的借鉴意义。     

回采巷道锚杆支护两帮稳定性分析

根据巷道围岩应力变化特点结合锚固体变形破坏的相似材料模拟试验, 分析了巷道两帮锚固体的变形破坏特征, 指出锚杆支护巷道两帮表面主要发生张性破坏, 锚固体内部发生剪切破坏, 据此建立起回采巷道锚杆支护两帮稳定的分析模型, 提出了两帮稳定的判别准则, 即锚固体中锚杆的拉应变必须小于锚杆的允许拉应变, 在巷道两帮围岩较松软时, 还必须满足巷道周边位移值的要求