Failure mechanism of bolting support and high-strength bolt-grouting technology for deep and soft surrounding rock with high stress

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.

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.

Bolt-grouting combined support technology in deep soft rock roadway

Analyzing the mineral composition, mechanical properties and ground stress testing in surrounding rock,the study investigated the failure mechanism of deep soft rock roadway with high stress. The boltgrouting combined support system was proposed to prevent such failures. By means of FLAC3D numerical simulation and similar material simulation, the feasibility of the support design and the effectiveness of support parameters were discussed. According to the monitoring the surface and deep displacement in surrounding rock as well as bolt axial load, this paper analyzed the deformation of surrounding rock and the stress condition of the support structure. The monitor results were used to optimize the proposed support scheme. The results of field monitors demonstrate that the bolt-grouting combined support technology could improve the surround rock strength and bearing capacity of support structure, which controlled the great deformation failure and rheological property effectively in deep soft rock roadway with high stress. As a result, the long term stability and safety are guaranteed.

Stress evolution and support mechanism of a bolt anchored in a rock mass with a weak interlayer

By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.

特大断面导流隧洞施工技术在水利枢纽工程中的应用

该文以某水利枢纽工程为例,探究特大断面导流隧洞施工中爆破开挖与锚喷挂网联合支护技术的应用。经前期地质勘察可知,隧洞围岩为Ⅱ~Ⅲ级,围岩稳定性较好,采取先进行光面爆破再进行洞身开挖的作业方案。在清运碴石、清除危石后,在开挖面上初喷混凝土形成稳定工作面。然后打入锚杆、挂钢筋网并进行二次衬砌,对导流隧洞支护,营造安全的施工环境。拱顶沉降监测数据表明,在导流隧洞开挖后的30 d内,每日平均沉降速率为2.09 mm,在允许范围之内,本次特大断面导流隧洞施工效果符合预期。

11-104回风顺槽分区域差异性联合支护技术应用

同一巷道单一支护形式具有一定的局限性,无法有效实现巷道整体区域的稳定控制。本文以正益煤矿围岩条件复杂的11-104回风顺槽为工程背景,提出11-104回风顺槽分区域差异性联合支护技术,在正常区域采用锚网索联合支护技术,在围岩破碎区域采用锚网索注联合支护技术。该技术应用后,实现了11-104回风顺槽围岩的稳定控制。

煤柱回收工作面巷道围岩控制技术

为提高煤炭资源回收率、减少煤炭资源的损失浪费、延长煤矿的生产服务年限,南庄公司采取了大巷煤柱回收技术实践,通过高强度高预紧力锚杆支护技术实现了对破碎巷道的有效支护,围岩层次注浆技术实现了对巷道围岩的整体性加固,以上两项技术的应用使得煤柱工作面巷道得到有效控制,保障了煤柱的安全回采。

厚煤层小煤柱护巷耦合支护技术的优化与应用

长平矿原采用25~30m大尺寸煤柱护巷,为提高煤炭资源回收率,以4309工作面小煤柱沿空掘巷为工程背景,综合运用理论分析与工程类比等方法,确定小煤柱最佳尺寸为6m。沿空巷道采用综掘工艺,浅掘进、轻扰动的掘进方式,配合邻近巷道爆破切顶卸压工艺,选用锚网索耦合支护方式,及时对裸露围岩进行喷浆封闭,滞后注浆加固,有效提高煤柱抗压强度。现场矿压监测表明,巷道变形均在可控范围内,满足4309工作面安全生产需求。

Support technologies for deep and complex roadways in underground coal mines:a review

Based on geological and mining characteristics,coal mine roadways under complex conditions were divided into five types,for each type the deformation and damage characteristics of rocks surrounding roadways were analyzed.The recent developments of roadway support technologies were introduced abroad,based on the experiences of supports for deep and complex roadways from Germany,the United States and Australia.The history and achievements of roadway support technologies in China were detailed,including rock bolting,steel supports,grouting reinforcement and combined supports.Four typical support and reinforcement case studies were analyzed,including a high stressed roadway 1,000 m below the surface,a roadway surrounded by severely weak and broken rocks,a chamber surrounded by weak and broken rocks,and a roadway with very soft and swelling rocks.Based on studies and practices in many years,rock bolting has become the mainstream roadway support form in China coal mines,and steel supports,grouting reinforcement and combined supports have also been applied at proper occasions,which have provided reliable technical measures for the safe and high effective construction and mining of underground coal mines.

深部高应力巷道深-浅刚柔耦合锚注支护技术研究

针对深部高应力巷道围岩大变形与支护结构失效严重等问题,以皇后煤矿15108回风巷为背景,综合运用理论分析、数值模拟与现场工业性试验等方法。在对巷道围岩破坏机制进行深入分析基础上,提出了高应力巷道深-浅刚柔耦合锚注支护技术。对原始支护方案与深-浅刚柔耦合锚注支护方案进行对比分析。工程实践表明:深-浅刚柔耦合锚注支护方案较原始支护方案在围岩塑性区以及应力分布方面都有较为明显改善,巷道围岩变形量得到有效控制,实现了深部高应力巷道围岩稳定性控制。

Plastic zone analysis and support optimization of shallow roadway with weakly cemented soft strata

Based on a shallow roadway with weakly cemented soft strata in western China, this paper studies the range and degree of plastic zones in soft strata roadways with weak cementation. Geological radars were used to monitor the loose range and level of surrounding rocks. A mechanical model of weakly cemented roadway was established, including granular material based on the measured results. The model was then used to determine the plastic zone radium. The predicted results agree well with measured results which provide valuable theoretical references for the analysis of surrounding rock stability and support reinforcing design of weakly cemented roadways. Finally, a combined supporting scheme of whole section bolting and grouting was proposed based on the original supporting scheme. It is proved that this support plan can effectively control the deformation and plastic zone expansion of the roadway surrounding rock and thus ensure the long-term stable and safe mining.

-980m大断面泵房围岩控制研究

针对邢东矿二水平下部车场泵房硐室顶板野青灰岩,其上为层理、节理极为发育的页岩,支护难度大的情况,采用锚注联合支护技术,锚杆加固技术与注浆加固技术的有机结合充分利用二者各自的优点,极大改善围岩结构及其性质,提高了围岩整体性和自承载能力。现场矿压观测表明:经过最长164 d的观测,硐室变形速率小于0.5 mm/d,变形量小于130 mm。

赵官煤矿2707W工作面沿空留巷应用研究

为解决传统沿空留巷工作面围岩变形严重及支护困难的问题,提出“切顶预裂+锚注支护+锚索桁架+U型钢棚护巷”的无煤柱沿空留巷方案。依托赵官煤矿2707W工作面为工程背景,运用理论分析、数值模拟及现场实测的方法,对其关键参数进行优化研究。结果表明:切顶卸压的实施,能够使巷道应力集中向实体煤侧更深处转移,有效地降低巷道围岩应力;锚注支护的实施,有效地降低巷道的垂直应力,减小巷道变形,提高沿空留巷效果;现场工业性试验表明:“切顶预裂+锚注支护+锚索桁架+U型钢棚护巷”的留巷方案,能够有效控制巷道围岩变形,满足沿空留巷要求,实现无煤柱沿空留巷开采。

浅埋深薄基岩巷道锚注加固技术研究

针对红柳林煤矿浅埋深薄基岩巷道顶板锚固力低的难题,分析了风化基岩分布特征以及矿物成分,开展了薄基岩注浆加固试验,分析了薄基岩巷道注浆加固机理,提出了巷道锚注加固技术方案,并开展了井下工程实践,分析了工程应用效果。结果表明:风化薄基岩黏土矿物成分含量高,增大了顶板岩体软化和膨胀变形,影响巷道围岩稳定性;井下注浆充填了风化基岩裂隙,封堵了顶板水渗流通道,提高了顶板完整性,增大了薄基岩层的抵抗破坏的能力;通过锚索注浆达到了较好的注浆固结效果,锚杆(索)初期受力缓慢增大,随后基本保持稳定,锚杆受力55~67 kN,锚索受力92 kN左右,顶板离层量3 mm左右,巷道围岩变形明显减小,达到了较好的巷道支护效果,表明锚注加固技术可有效解决浅埋深薄基岩巷道变形控制难题。

深井破碎围岩巷道协同支护技术研究与应用

为解决煤炭资源进入深部开采时破碎围岩巷道支护所面临的变形大、易失稳、难支护等问题,提出“架棚+锚杆(索)+注浆”协同支护方案,运用钻孔窥视确定巷道围岩结构稳定性、裂隙发育特征,FLAC3D数值模拟对比分析常规锚网喷支护、锚注支护及棚锚注协同支护塑性区分布,结果表明:棚锚注协同支护技术较另两种方案表现出更好的支护效果,塑性区分布范围明显减少,应力集中现象得以缓解,支护巷道模拟变形量与工程监测较为接近。工程试验表明:采用常规锚网喷支护、锚注支护巷道仍存在较大变形,不能保持长期稳定,棚锚注协同支护巷道变形明显降低,应用期间顶板下沉量较常规锚网喷支护降低了68%,两帮位移降低了52%,满足巷道支护稳定要求。棚锚注协同支护技术对深部破碎围岩巷道变形控制效果显著,尤其在掘进影响期控制围岩作用表现突出。

大断面破碎顶板巷道锚注支护技术研究

以腾晖矿2-205综放工作面为背景,结合2-2051回采巷道具有大断面及部分区域顶板破碎的特点,拟采用注浆锚索和单体液压支柱配合π梁的复合支护方式对顶板破碎区域进行补强支护,以保证回采期间巷道顶板安全。通过分析2-2051回采巷道超前支承压力分布规律,指导其补强支护设计。分析了注浆锚索补强支护原理和强度,并开展巷道补强支护强度计算,在此基础上完成了巷道支护方案设计。研究结果表明:采用注浆锚索和单体液压支柱配合π梁的复合支护方式,结合巷道围岩结构特征、超前支承压力分布规律、注浆锚索补强支护原理和巷道补强支护强度计算,分析、计算得出了合理的支护方案参数,有针对性地做到了顶板破碎区域补强支护方案的实施。现场工业试验结果表明,回采巷道顶板破碎区域采用锚注补强支护技术后,巷道顶板变形得到有效控制,可以满足回采工作面安全高效的要求,对其他类似条件的矿井具有工程推广价值。

西柏树矿巷道预注浆技术研究及应用

西柏树矿24号脉855 m中段西脉外运输巷围岩破碎,伴随有较大涌水,使得掘进存在安全隐患大、单班台效低、支护费用高等问题。为了确保巷道掘进的安全及效率,提出了超前探水结合超前预注浆、超前长锚杆支护技术措施,给出了注浆孔工程布置、注浆工艺参数,并进行了现场应用。结果表明:使用超前预注浆堵水、注浆加固,结合超前锚杆,保证了掘进速度,安全系数大大增加,有效减少了人员在淋水环境下作业时间,取得了月进尺45 m,支护成本下降13%的经济技术指标,可为类似矿山提供参考。

高应力巷道底板卸压及围岩锚注支护技术

针对平煤八矿高应力回风上山巷道围岩软弱易破碎、巷道底鼓严重的问题,采用底板卸压和围岩锚注的支护思路,提出了“混凝土+锚网+注浆+卸压槽”的多层次联合支护方案。结合UDEC数值软件确定了卸压槽的宽度为1.2 m,深度为2.0 m。钻孔窥视表明,深孔、浅孔交替注浆后,浆液扩散半径达到3.0 m,巷道围岩整体性较好,巷道变形得到了有效控制。该技术解决了巷道在支护过程中遇到的问题,保证了矿井的安全开采,可为类似矿井提供借鉴。

松软厚煤层留顶煤动压巷道支护技术研究

针对松软厚煤层留顶煤动压巷道,在前期巷道地质力学参数测试基础上,分析巷道变形破坏的影响因素,通过围岩应力数值模拟分析,提出了针对性的松软厚煤层留顶煤巷道的高预应力注浆锚杆锚索支护方案。井下实践表明,采用高强度、高刚度、低密度的注浆锚杆锚索组合支护技术,可有效地控制巷道围岩变形,实现工作面安全回采。

8102高应力软岩巷道支护参数设计与应用

8102高应力软岩巷道拟使用锚网索喷+锚注联合支护方式,并设计了支护参数。本文采用FLAC3D模拟未支护、初次锚网索喷支护、二次锚注支护后巷道围岩变形及塑性区分布情况,分析可知,设计的支护参数可保证8102巷道围岩稳定性。现场围岩变形量监测结果表明,巷道围岩变形主要集中在前30 d内,二次锚注支护需在初次支护30 d后进行。