以河南某矿23150工作面为工程背景,采用现场实测、理论分析、数值模拟等方法,研究了巨厚砾岩下特厚煤层巷道掘进异常的机理以及开采局部保护层的防治方法.得出以下结论:采空区上覆岩层处于非充分采动状态,巨厚砾岩尚未破断,自重应力与巨厚砾岩传递应力叠加形成了下平巷的高应力场,高应力是特厚煤层巷道冲击危险的主要原因;合理的局部保护层开采范围是保证巨厚砾岩下特厚煤层巷道处于低应力状态的关键.通过建立局部保护层宽度计算的力学模型,推导了局部保护层开采范围,并通过数值模拟验证了理论计算的正确性.

针对山东某煤矿首采工作面出现的矿震异常现象,通过现场数据统计和理论分析,探明了该矿矿震为原岩应力与构造应力耦合型.基于应力和能量转移原理,提出了该矿矿震的发生机理为两种应力的耦合,并建立了原岩应力"破坏-重塑"后与断层构造应力叠加的物理模型;为确立合理的工作面开切眼位直,推导出了此类型矿震发生的判断准则,最终建立了原岩应力破坏、应力场演化和断层活化失稳诱发矿震之间的相互作用关系.

In order to develop a satisfied support scheme for roadways excavated in soft rock and subjected to large deformation in coal mines, a combined supporting system is proposed, which includes steel mesh, bolt, anchoring cable, shotcrete, compressible U-shaped steel, foamed concrete damping layer, and fractured rock cushion layer. The interpretation of the behavior of the supporting system is carried out by numerical analysis and field monitoring. The results from the numerical analysis reveal that: due to the fact that the foamed concrete absorbed most of the deformations of the surrounding rock, the shrinkage of the U-shaped steel was significantly reduced, and the relationship between the average axial force of the U-shaped steel and the foamed concrete thickness is a second order equation. It is further noticed that, in engineering practice, the damping effect was no longer evident when the thickness of foamed concrete exceeded 30 cm. The field monitoring results show that both the force sustained by the U-shaped steel and the displacement of the surrounding rock exhibited a trend of increase in the first 20 days after the support system was formed but the increasing trend reduced after that, which means the proposed combined supporting system is effective to control the large deformation of roadways excavated in soft rock.

The aim of this study is to resolve the present control problems and the corresponding high-strength anchor cable control technology in deep large section roadways. This study was based on the Hoek-Brown criterion and the upper bound theorem of the limit analysis and also considered the stress of surrounding rock in the roof and the effect of supporting the load. On the above basis, the roof caving mechanism of large-section roadways was acquired. Furthermore, a design method for roofs was put forward for the minimum length and the pre-tightening force of an anchor cable. Since the design parameters of anchor cables was affected by established sensitivity indexes, it is important to investigate the effects of established sensitivity indexes on factors, such as the roadway's width, the specific weight of the rock mass, the stress in the surrounding rock, the compressive strength and the tensile strength of the rock mass, anchor cable layout spacing and vertex anchor cable laying angle. According to the actual field conditions,engineering suggestions are proposed for controlling surrounding rocks in the deep large-section roadway. Finally, this design method was applied to determine the roof anchor parameters of transport gateway of 1305 Island Coal Face in the Kilometer Deep Well Zhaolou coal mine, which effectively controlled the deformation of surrounding rock. From research results, only when the roof anchor cable was anchored in stable rock and enough pre-tightening force was exerted, the roof rock caving and damage can be effectively controlled in high-stress large-section mining roadways. It is found that roof pre-tightening force for anchor cable decreased with the increase of tensile strength, compressive strength and empirical parameter A of rock mass. Besides, this roof pre-tightening force increased with increasing the width of the roadway, the specific weight of rock mass, the stress in the surrounding rock, the compressive strength and the tensile strength of rock mass, anchor cable layout spacing, vertex anchor cable laying angle and empirical parameter B of rock mass. Moreover, the highest sensitivity of all the influencing factors turned out to be the surrounding rock stress. This indicates that special attention should be paid to the influence of in-situ stress of the surrounding rock when designing the deep high-stress roadways. Therefore, the effective release of the surrounding rock stress can be achieved by using the high strength, high elongation anchor cable and adding the yieldable device. Meanwhile, the integrity of the surrounding rock can be improved by applying high pre-tightening force and grouting reinforcement, resulting in better control performance of surrounding rock.

Aiming at the support difficulties of mine galleries under the complex geological conditions of high buried depth, high in situ stress and tectonic fractured zones, a novel square-steel-confined-concrete (SSCC) arch centering supporting system is proposed in this paper. To validate the feasibility of this supporting system, a uniaxial compression test on an SSCC short column is performed and the results illustrate that it has better ductility and higher bearing capacity than the U-shaped column. Numerical analysis on the mechanical behaviors of SSCC arch centering is conducted considering three factors of core concrete strength, steel tube thickness and confinable effect coefficient. Two influence indexes of steel tube thickness (mu(t)) and core concrete strength (mu(c)) influencing the ultimate bearing capacity are put forward and mu(t) has more significant influence. Therefore, an SSCC arch centering (side length 150 mm, tube thickness 8 mm and filled C40 concrete) is determined to perform laboratory and in situ experiments. Combined with numerical simulations, the deformation failure behaviours of the SSCC arch centering are eventually obtained. The laboratory experimental results show that the maximum deformation appears near the spandrel of the arch centering and the ultimate bearing capacity is 1286.9kN. An SSCC and a U-shaped arch centerings have been simultaneously used in the supporting system of the gallery in Zhaolou coal mine project, and the monitoring results (after 157 days) show that their average displacement of the SSCC arch centering is 10.33 mm, which is only 18.3% of that obtained in the U36 arch centering. The above research results indicate that this kind of SSCC arch centering supporting system could efficiently control the deformation of the surrounding rock mass in mining galleries.

In deep underground mining, the surrounding rocks are very soft with high stress. Their deformation and destruction are serious, and frequent failures occur on the bolt support. The failure mechanism of bolt support is proposed to solve these problems. A calculation theory is established on the bond strength of the interface between the anchoring agent and surrounding rocks. An analysis is made on the influence law of different mechanical parameters of surrounding rocks on the interfacial bond strength. Based on the research, a new high-strength bolt-grouting technology is developed and applied on site. Besides, some helpful engineering suggestions and measures are proposed. The research shows that the serious deformation and failure, and the lower bond strength are the major factors causing frequent failures of bolt support. So, the bolt could not give full play to its supporting potential. It is also shown that as the integrity, strength, interface dilatancy and stress of surrounding rocks are improved, the bond strength will increase. So, the anchoring force on surrounding rocks can be effectively improved by employing an anchoring agent with high sand content, mechanical anchoring means, or grouting reinforcement. The new technology has advantages in a high strength, imposing pre-tightening force, and giving full play to the bolt supporting potential. Hence, it can improve the control effect on surrounding rocks. All these could be helpful references for the design of bolt support in deep underground mines.

The invention discloses a mining influence tunnel dynamic monitoring and stability evaluation method which comprises the following steps: step 1, arranging a high-precision micro-seismic monitoring system and an introscope; step 2, collecting data before mining influence; step 3, collecting data after mining influence, wherein the specific implementation steps of the step 3 are the same as those of step 2; step 4, analyzing the stability of surrounding rock, namely respectively calculating to obtain a surrounding rock rupture range increase rate, a surrounding rock rupture energy increase rate, a surrounding rock rupture event unit volume density increase rate and a surrounding rock rupture degree increase rate based on a surrounding rupture position, surrounding rack rupture energy, surrounding rock rupture times and surrounding rock rupture degree before and after mining influence; step 5, quantitatively evaluating the tunneled tunnel stability below a coal pillar of mining influence, namely, based on surrounding rock evaluation values obtained in the step 4, establishing quantitative evaluation indexes of tunnel tunneling stability under mining influence by use of a weight analysis method, and performing quantitative evaluation on the tunneled tunnel under mining influence.

为深入研究U型约束混凝土拱架的力学性能及破坏特征,以直腿半圆形拱架为例,考虑荷载、侧压力系数、节点刚度比、截面刚度、高-径比等影响因素,建立任意节数的U型约束混凝土拱架的力学模型,得到直腿半圆形拱架理论计算方法.综合分析了U型约束混凝土拱架的力学性能及破坏特征,开展地下工程约束混凝土拱架1:1室内力学试验,结合理论计算、数值试验和实体比例室内试验,证明了任意节数U型约束混凝土拱架理论计算的正确性.研究表明:内力受荷载、侧压力系数和高-径比的影响较大;理论计算中内力最大的两个部位为直腿3/4高度位置和拱项位置;在均压情况下,直腿半圆形拱架的变形形态为"拱顶上升,拱腿内敛,整体变瘦高".研究成果可为深部巷道U型约束混凝土拱架力学性能及破坏特征研究提供理论和试验依据,为现场工程设计实践提供指导.

为研究不同锚固长度对巷道围岩的控制效果,从理论方面推导了锚杆应力分布规律,建立了不同锚固长度下巷道围岩力学分析模型,考虑分析了锚杆直径、围岩强度参数、锚固长度、预紧力、布设间距等影响因素,给出了巷道锚杆支护设计的工程建议措施,并通过开展现场试验验证了本文理论研究成果的正确性.研究表明:锚杆受力主要集中在锚固段端头1/3范围内,且沿长度方向杆体剪应力与轴力不断递减;在软岩中更利于锚杆锚固作用的发挥;施加高预紧力,并留设一定的自由段长度,有利于锚杆预紧力在围岩中扩散,可形成有效的锚固围岩承载结构,充分发挥杆体支护潜力;当锚杆布设间距较大时,可通过提高预紧力、适当减少锚固长度来增加预紧力对围岩的控制效果.

对全尺寸直腿半圆形拱架进行了室内试验和数值分析,室内试验表明:拱架的变形破坏呈现“拱腿内挤,拱顶外凸”的特点,拱腿和拱顶部位的钢材达到塑性状态,极限承载力Fe=1 228kN.针对充填C30～C80强度混凝土以及壁厚4～12 mm的SQCC拱架的数值分析表明:SQCC150-8-C30拱架的极限承载力为1 217 kN,拱架极限承载力差异率为0.89％,拱架变形破坏特征和钢材的应力应变状态都和室内试验结果吻合.通过数值分析可见钢管壁厚比核心混凝土强度对拱架极限承载力的影响更为显著;建议壁厚8 mm,C30或C40核心混凝土强度的SQCC拱架较为适用.

In order to study the characteristics of the deep shaft full-mechanized caving mining abut-ment pressure distribution, field measurement focusing on vertical stress has been carried out by using microseismic and online stress monitoring system at 1306 working face in Zhaolou mine.The research shows that the process of workface extracting can be divided into three stages: initial mining stage,“square stage”and normal mining stage. Advanced abutment pressure of the“square stage”exists three parts, that is the initial affect range, significantly affect range and severe affect range. The initial and normal mining stage has no obvious rising stage. The abutment pressure affect scope and the peak stress of the“square stage”are 1.5-1.7 times higher than those of the other two stages. According to the char-acteristics of abutment pressure distribution, reasonable advance support distance and controlling meas-ures of different recovery stages were determined.

巨野矿区赵楼煤矿千米深井工作面顺槽多为典型厚顶煤巷道,围岩稳定性差,巷道破坏严重,控制困难.针对该问题,根据顶板锚索梁的不同布置方式,设计了横梁、纵向单梁、纵向双梁及纵横组合4种锚索梁支护对比方案,通过数值模拟得到了不同布置方式下围岩内部应力分布状态.结果显示:纵横组合方案作用下顶板连续受压区范围及数值最大(应力0.025～0.04MPa),纵向单梁方案次之.分析其作用机制在于:纵向单梁方案中锚索和钢梁共同作用对项板巷中部位的围岩产生更强的控制作用,形成的受压区面积和压应力值较大;纵横组合方案在纵向单梁方案优势基础上进一步增强了支护系统对巷中两侧顶板煤岩流动的控制,将顶板煤岩保持在相对更好的受力状态.最后通过现场试验对各方案的围岩控制效果进行了对比分析,验证了上述机制分析结论的正确性.

A new kind of admixture for the shotcrete was proposed, its main ingredient is silica fume (61.3%) and bentonite (38.3%), plus a small amount of polyacrylic acid (0.4%). The influences of the admixture on the liquidity of shotcrete were studied, it is results that: 1) with the increase of the cement content, the workability of the shotcrete improves significantly; 2) with the increase of admixture dose, the bleeding rate significantly decreases; 3) after adding admixture, the anti-segregation capabilities are mostly above 95%. Even if the shotcrete with admixture added in has high fluidity, it also has good anti-segregation capability; 4) the shotcrete before adding admixture has much dust around while the dust is obviously decreased after adding admixture.

The instability of super-thick strata will induce tremors with large energies during repeated mining.Based on this phenomenon, the caving and movement rules of overlying strata during repeated mining were analysed, the structural form of key block in the super-thick strata as well as the stress situation and fracturing instability characteristics in different areas were further studied.Finally, the tremor mechanism induced by repeated mining was obtained.That is, first, the increase of mining height activates the gob strata, and leads to sliding or shearing instability of the hinged balance structure in roof strata, thus triggering the occurrence of mining-induced tremors.Second, the external expansion of strata movement line enlarges the horizontal and vertical move ranges of roof strata on the border areas, which results in the large-scale instability of the super-thick strata in the highly-concentrated stress area and then in terms of rock burst mechanism induced by tremor, the optimization of working face design, disturbance reduction to dangerous zones and structural strength enhancement of roadway surrounding rock were carried out to effectively ensure the mining safety in the protected face, and achieved the control goal of tremor occurred with rock burst disaster-free.

In order to solve the problem in deep high-stress rock roadway and roadway with structural fracture zone,a new support system—square-type steel confined concrete( SQCC) was developed. And the important component of it,square-type steel confined concrete arch centering was further studied. The inner force expressions of straight wall semicircle arch was deduced with the force method,and combined with the engineering practice to calculate the inner force distribution of four section arch,which is the field application,under uniformly loads. From the inner force distribution of arch centering,that arch legs and vault is the key position of the arch centering failure is confirmed. Through the strength analysis of the SQCC component to check the key parts of the possible,get that first failure part is arch leg and the ultimate bearing capacity of SQCC arch centering is 1 315 k N. The mechanics experiment of SQCC arch centering are carried out by using designed 1 ∶ 1 mechanics test system of confined concrete arch centering. Meanwhilecombined with the results of numerical experiments on SQCC arch centering by using ABAQUS software. Through the analysis on the error rate of ultimate bearing capacity,δFe- Ft=- 7. 1%,δFe- Fn=- 1. 1%,the key position,the inner force,deformation and stress,research the mechanical properties and faileure mechanism of SQCC arch centering,and verify the conclusion based on the theoretical arithmetic and laboratory experiment is right.

To investigate the support of semicircle arched roadway,the roof failure mechanism,considering surrounding rock stress and bolting support,was constructed based on nonlinear Hoek-Brown failure criterion,and a simplified method for designing the pre-tightening force of roof bolts at the early stage after roadway excavation was proposed based on upper bound method. In addition,the recommended engineering measures were also provided accordingly,and the supporting effect of bolts with high strength and high pre-tightening force was verified through a field application. The results show that only imposing enough pre-tightening force after roadway excavation can effectively prevent roof falling. With the improvement of the strength parameters of rock mass,the required pre-tightening force of single rock bolt decreases,while increases with the increases of bolt spacing and surrounding rock stress. Adopting bolting support components with high strength,high tenacity and imposing high pre-tightening force,or adopting grouting reinforcement in soft,loose and broken surrounding rock can obtain more ideal control effects.

DDARF (discontinuous deformation analysis for rock failure) method was used to research the roadway along goaf of 11302 workface in Zhaolou Colliery. In order to get its failure deformation and control mechanism, DDARF was first used to analyze the crack propagation of single joint anchored specimen under uniaxial compression, then the stimulation result of real roadway was compared with monitoring data from geomechanical model test and field test, to verify its correctness. The focus was on the crack evolution law of surrounding rock in the roadway along goaf. In order to quantitatively analyze the crack evolution in DDARF calculation, two indexes of R-c (crack ratio) and R-r (crack reduction ratio) were defined. Research results showed that the DDARF simulation results were consistent with uniaxial compression test of single joint anchored specimen. In the DDARF calculation of surrounding rock deformation in the roadway driving along goaf, it was shown that the deformation of coal side next to goaf was the largest, followed by roof and integrated coal side, floor was the least, and the monitoring data from model test and field test were both consistent with the result. According to the two indexes R-c and R-r, quantitative analyses was conducted to compare the crack evolution of non-anchored and anchored roadways, and the result was consistent with the deformation trend that is R-cI > R-cII > R-cIII > As the surrounding rock had been seriously crushed, although supporting scheme was effectively, the max crack ratio R-cI with anchor supported was still 2.13 times of the R-cIII . In order to maintain the stability of surrounding rock, the key parts of zone. and zone. should be strengthened besides asymmetric supporting with anchors. For the stimulate result was closer to actual engineering, DDARF method could not only be used to research crack evolution and failure deformation, but also guide countermeasure to control these roadways effectively.

Determination of reasonable coal pillar width is key for ensuring stability of surrounding rock of fully mechanized caving roadway driving along next goaf. Taking track roadway of 11302 workface in Zhaolou colliery as the engineering background，a new side abutment pressure monitoring method was proposed；and the reasonable coal pillar width was determined by using the method of field stress monitoring and numerical simulation. Field stress monitoring and numerical analysis results show that the influence scope of workface side abutment pressure is 50–56 m，and low stress zone width is 12–15 m，considering pillar stress environment，pillar width should not be larger than 7–10 m. Meanwhile，considering being propitious to bolt anchoring，width of coal pillar should not be less than 4 m. Various elements such as coal pillar stability，secondary disaster control and resources recovery were considered comprehensively. Finally，the reasonable width of segment pillar is determined as 5 m. Reasonable pillar width is verified by using large-scale geomechanical model test and field test. Monitoring results show that variation of surrounding deformation along the empty wall is largest，followed by roof and entity wall，floor is least. After roadway driving along next goaf stability，roof to floor convergence is 271 mm；two walls convergence is 359 mm；the effect of roadway surrounding rock is well. Bolts and anchors forces are in their yield range；and set aside a sufficient margin for the recovery period. The results can provide a reference for segment pillar setting in other mines with similar mining conditions.

According to field investigation and deformation monitoring of roadway driving along goaf in fully mechanized top coal caving face in Zhaolou mine, failure characteristics of roadway surround-ing rock have been analyzed and its deformation failure mechanism has been deeply revealed. Results indicates that low surrounding rock density, high in-situ stress, large destruction scope, unreasonable supporting structure and parameters, complex stress environment and large section size are the main reasons of surrounding rock failure and deformation. Based on control principle of intensive-yielding-coupling support and key parts reinforced support, supporting measures of roof bolt net strip cable, lon-gitudinal strip+two sides anchor net ladder cable, longitudinal steel ladder+narrow coal pillar cable reinforcement and gunite+entity coal side drilling to relief stress are proposed. In addition, field test has been implemented. After roadway driving along next goaf stability, the effect of roadway surround-ing rock is good. The maximum force of bolts and anchors are within their yield range, and set aside a sufficient margin for the recovery period. The results can provide a reference for similar complex and difficult supporting roadway.