深井软岩巷道预留刚隙柔层厚度的确定及应用

针对深井软岩巷道围岩变形、破坏的特点,提出了预留刚隙柔层的厚度就是巷道围岩出现松动破坏前的塑性区径向位移．采用Bonaitin-Thomson模型对分区的巷道围岩进行了力学分析,推导出黏弹性区、稳定塑性区的径向位移计算式,并讨论了影响预留刚隙柔层厚度的主要因素．结果表明：巷道围岩位移与时间有关,且随时间的增长而增加,并最终趋于一稳定值．预留刚隙柔层厚度随巷道半径和原岩应力的增大而加大,随一次支护强度的增加而减小,但受一次支护强度的影响较小．曲江矿运输大巷预留刚隙柔层37cm,使巷道围岩充分释放变形能的同时又不损害围岩自身的支撑能力,二次支护后,巷道围岩变形量较小．     

深井软岩巷道底板卸压钢丝绳网锚注支护技术研究

针对平顶山天安煤业股份有限公司一矿深井软岩回风上山巷道工程地质条件和围岩变形特征,采用数值计算方法,研究了底板卸压槽卸压前后巷道围岩应力场、塑性区的变化规律,分析了底板卸压槽卸压机理,提出了钢丝绳网锚注支护技术,并进行了工业性试验。研究结果表明:(1)巷道底板开掘卸压槽卸压后,底板围岩垂直应力和水平应力的高应力区及其峰值应力均向底板深部转移。卸压后底板同一深度的围岩应力均小于卸压前的围岩应力;卸压后巷道顶底板和两帮围岩的塑性区范围均增大,底板卸压效果明显。(2)深井巷道围岩的破碎区和部分塑性区是支护的重点。回风上山巷道采取开挖底板卸压槽、钢丝绳网锚杆支护和围岩注浆加固等支护措施后,在围岩中形成了锚注体支护圈,提高了围岩的强度和自身承载能力。巷道围岩经历加速变形阶段、减速变形阶段和稳定变形阶段后,一直处于稳定变形状态。卸压槽+钢丝绳网锚注支护在回风上山巷道的支护试验取得成功,可为深井软岩巷道支护提供参考依据。     

对轴对称荷载作用圆巷围岩理想弹塑性分析解的讨论

对轴对称荷载作用圆巷围岩理想弹塑性分析解——Kastner解适用于软岩和小变形情况,若用于非软岩和大变形情况,从Kastner方程会导得：不论巷道围岩塑性变形多大,巷道周边切应力恒等于岩体峰值强度;围岩所承受的地应力可以随围岩塑性区半径增大而持续增大,随巷道周边位移增大而持续增大;此外,Kastner解中切应力分布曲线在围岩弹、塑性区交界处有尖峰向上的应力集中.采用符合岩石实际的弹性、非线性硬化和软化光滑连接的应力-应变关系得到的巷道围岩分析解,可以弥补以上三点不足,恰当地反映巷道临界深度和巷道围岩自承地应力极限问题;所绘出的切应力分布曲线在围岩弹、塑性区交界处光滑连接,因而有更广的适用性和精确性,对巷、隧道围岩大变形支护设计有参考作用.     

强膨胀软岩巷道变形特性及控制对策研究

为解决强膨胀软岩巷道支护问题,以红庆梁煤矿强膨胀软岩巷道支护工程为研究对象,通过理论分析和现场调研,分析了强膨胀软岩巷道变形特性.利用MIDAS/GTS建立强膨胀软岩巷道弹塑性数值仿真模型,分析了采用锚网喷架联合支护方案时巷道塑性区范围、应力分布、表面位移以及锚杆和U型钢可缩支架的受力特征.进行现场测试,得到了锚网喷架联合支护方案条件下巷道围岩变形规律.结果表明:采用锚网喷加U型钢可缩支架组成的联合支护体系将有效地提高支护结构整体刚度,增强围岩的自稳能力和自承能力.     

巷道围岩强度弱化规律及其应用

认为软岩巷道稳定性应采用动态支护的观点分析．用巷道周边位移表达的损伤因子来描述围岩阶段性变形特征及破坏过程,分析与之对应的围岩强度弱化规律,在此基础上提出了喷锚注分阶段加固技术,并对合理滞后注浆时间的确定进行了研究．最后,介绍了一个应用实例     

软岩巷道开挖-支护过程承载结构稳定性分析

为研究软岩圆巷开挖面附近围岩在"锚网喷"支护后围岩力学承载结构的稳定性,依据围岩变形及受力特征,沿巷道径向依次将围岩划分为破裂区、软化区和弹性区,其中,"锚网喷"支护主要作用于破裂区中.基于统一屈服准则、增量型本构关系和软岩力学模型,得到了"围岩-支护"相互作用下的围岩应力和变形解.考虑切向应力和等效剪应力的集中以及围岩强度,将围岩力学承载结构由浅入深依次划分为"弱-主-强"结构.通过算例分析,可知围岩力学承载结构的承载范围和承载位移及其剪切应力,受锚杆支护间排距、软化模量和开挖空间效应等因素的影响.在工程实践中,基于"围岩-支护"力学承载结构理论,设计的"锚网喷注"支护方案能够提高围岩强度、降低软岩巷道变形量,保证了掘巷初期的稳定性.     

上下采空区巷道围岩力学特征及支护技术

潘三矿西翼-810 m皮带机大巷（西二～西三段）受上下采空区的影响,其所处的工程条件复杂,巷道支护困难。对此,建立理论模型,对巷道围岩力学状态进行分析,得出围岩应力和损伤破裂半径的表达式。分析了在上下采空区的影响下,岩体卸压扰动和强度劣化对塑性损伤区及松动破裂区半径的影响。提出了锚网＋锚索桁架＋喷浆＋注浆锚索注浆的复合支护技术,为上下采空区影响下的巷道提供一些支护指导。     

古汉山矿东大巷“钢棚+注浆”支护工程实践

针对焦作矿区古汉山矿东大巷围岩属高应力、节理化、强膨胀的极软岩特性,采用一次拱形钢棚支护、二次锚注支护的"钢棚+注浆"支护技术方法,有效控制了巷道的强烈变形,避免了巷道维修,取得了软岩支护的最佳效益.     

古汉山矿东大巷"钢棚+注浆"支护工程实践

针对焦作矿区古汉山矿东大巷围岩属高应力、节理化、强膨胀的极软岩特性,采用一次拱形钢棚支护、二次锚注支护的"钢棚+注浆"支护技术方法,有效控制了巷道的强烈变形,避免了巷道维修,取得了软岩支护的最佳效益.     

深部软岩巷道深-浅耦合全断面锚注支护研究

基于对深部软岩巷道变形和破裂特征的长期监测结果,提出了以"中空注浆锚索和高强注浆锚杆"为核心的新型深-浅耦合全断面锚注支护技术体系.借助渗流力学理论建立了深-浅耦合锚注浆液的渗流基本方程,并结合COMSOL软件模拟再现了浆液在围岩内的渗透扩散过程.结果表明:注浆锚索和注浆锚杆所注浆液使巷道浅部围岩形成完整的锚注加固圈,而注浆锚索同时使巷道深部围岩形成局部锚注加固体,两者协调耦合作用,形成互为支撑的承载体,完善了深-浅耦合全断面锚注支护的理论体系和加固作用机理.现场监测证明该支护体系有效地控制了巷道围岩的变形与破坏.     

Zonal disintegration phenomenon in enclosing rock mass surrounding deep tunnels—mechanism and discussion of characteristic parameters

The mechanism of the zonal disintegration phenomenon (ZDP) was realized based on the analysis of the stressedstrained state of the rock mass in the vicinity of the maximum stress zone, which resides in the creep instability failure of rock mass due to the development of a plastic zone and transfer of the maximum stress zone within the rock mass. Some characteristic parameters of the ZDP are discussed theoretically. In first instance, the analytical critical depth condition for the occurrence of ZDP was obtained, which depends on the characteristics and stress concentration coefficient of the rock mass. Secondly, based on creep theory, the expression of the outer radius of the undisturbed zones in the deep rock mass was obtained with the use of an improved Burgers theological model, which indicated that the radius depends on the characteristics of the rock mass and the depth of excavation and increases quasi-linearly with the rise of creep compliance of the rock mass. Finally, the formula for the distance of the most remote fissured zone away from the working periphery was derived, which increases logarithmically with the increase in the ratio of the in-situ stress and ultimate strength of rock mass. The distances between fissured zones are discussed in qualitative terms.     

采用总荷载不变法的非静水压隧道摄动拓展解

为描述实际地应力场下隧道塑性区演化规律和支护设计原则,基于Mohr-Coulomb准则和弹-脆-塑性模型,采用总荷载不变法并引入弹性区应力摄动解,建立了非静水压力下圆形隧道水平轴和竖向轴处的塑性区半径方程,继而利用几何相似原理拓展至其他方位角处,并与文献总荷载不变法(以应力基尔希公式为基础)、Kastner法、复变函数法和实测数据进行对比,结合非关联流动法则推导塑性区位移解析解,探讨侧压力系数与脆性软化对隧道塑性区边界线、塑性区位移分布和围岩特征曲线的影响特性。结果表明：相比文献总荷载不变法和Kastner法,2阶摄动解作为非静水压圆形隧道的弹性区应力表达式更合理,且得到复变函数法的正确性验证;侧压力系数对隧道塑性区边界线的形状和范围均有明显影响,需针对具体方位角选择支护类型和尺寸以调控收敛约束交点处的支护压力与围岩稳定变形;隧道塑性区半径和洞壁位移随围岩峰后强度的降低而显著增加,宜使用弹-脆-塑性模型构建围岩特征曲线。     

基于Mogi-Coulomb强度准则的隧道围岩理想弹塑性解答

合理选择岩石强度准则对隧道应力及位移预测和支护设计都具有重要意义,基于Mogi‐Coulomb强度准则和理想弹塑性模型,通过中间主应力系数反映中间主应力的影响,推导了圆形隧道围岩应力和位移的解析解,并对所得结果进行比较与验证,得到了中间主应力和围岩抗剪强度参数的影响特性。研究表明：具有广泛的适用性和较好的可比性,Mohr‐Coulomb强度准则解答和Matsuoka‐Nakai准则解答均为其特例;结果关于中间主应力系数 b＝0.5对称,较好地反映了岩石强度的中间主应力效应及其区间性;粘聚力及内摩擦角对围岩塑性区半径和隧道洞壁位移的影响显著,应充分考虑中间主应力影响及围岩抗剪强度参数变化对隧道设计与施工的影响。     

Elasto-plastic analysis of the surrounding rock mass in circular tunnel based on the generalized nonlinear unified strength theory

The present paper aims to establish a versatile strength theory suitable for elasto-plastic analysis of underground tunnel surrounding rock. In order to analyze the effects of intermediate principal stress and the rock properties on its deformation and failure of rock mass, the generalized nonlinear unified strength theory and elasto-plastic mechanics are used to deduce analytic solution of the radius and stress of tunnel plastic zone and the periphery displacement of tunnel under uniform ground stress field. The results show that: intermediate principal stress coefficient b has significant effect on the plastic range,the magnitude of stress and surrounding rock pressure. Then, the results are compared with the unified strength criterion solution and Mohr–Coulomb criterion solution, and concluded that the generalized nonlinear unified strength criterion is more applicable to elasto-plastic analysis of underground tunnel surrounding rock.     

注浆、衬砌作用下非线性渗流隧洞弹塑性解

为探求深埋隧洞在非线性渗流条件下围岩-注浆圈-衬砌体系的力学行为,引入Izbash非线性渗流模型,给出了围岩-注浆圈-衬砌体系的水头分布,基于统一强度理论,考虑塑性区可能的分布位置,在注浆、衬砌支护作用下对隧洞位移、应力和塑性区半径进行了理论推导.通过算例将理论解与数值解对比分析,验证了研究方法的可靠性,并进一步探讨了考虑非线性渗流对富水山岭隧洞支护设计的工程意义.研究结果表明:非线性渗流对隧洞弹塑性力学的影响主要体现在围岩水力梯度系数m_1;围岩从低速非线性渗流向高速非线性渗流转变过程中,塑性区半径和位移越来越大,围岩应力有所减小;应从隧洞围岩的非线性渗流角度考虑注浆圈、衬砌支护厚度设计.研究成果为非线性渗流隧洞支护设计提供了理论依据.     

Influences of strain softening and seepage on elastic and plastic solutions of circular openings in nonlinear rock masses

Considering the influence of strain softening, the solutions of stress, displacement, plastic softening region radius and plastic residual region radius were derived for circular openings in nonlinear rock masses subjected to seepage. The radial stress distribution curve, ground reaction curve, and relation curve between plastic softening region radius and supporting force in three different conditions were drawn respectively. From the comparisons among these results for different conditions, it is found that when the supporting force is the same, the displacement of tunnel wall considering both seepage and strain softening is 85.71% greater than that only considering seepage. The increase values of radial displacement at 0.95 m and plastic softening region radius at 6.6 m show that the seepage and strain softening have the most unfavorable effects on circular opening stability in strain softening rock masses.     

Hoek-Brown破坏准则求解圆形硐室塑性区半径与修正的芬纳公式比较

目的 为定量确定围岩塑性区半径和给支护锚杆的深度设计提供科学依据.方法 以Hoek-Brown破坏准则为极限平衡条件,推求侧压力系数为1.0时圆形硐室理想弹塑性围岩的弹塑性应力和塑性区半径,运用Mohr-Coulomb准则直线拟合Hoek-Brown准则曲线和面积差补方法 ,求取等效的岩体Mohr-Coulomb强度参数后,建立相对塑性区半径随支护力和地质强度指标变化的二元非线性回归数学模型,并与源自于Mohr-Coulomb强度准则为屈服条件的修正的芬纳公式进行比较研究.结果 支护力每增加1.0 MPa,就可确保地质强度指标降低10～20的岩体中不会出现塑性区.在支护力较小和岩体质量较差情况下,采用Hoek-Brown破坏准则推导得出的塑性区半径和修正的芬纳公式计算得出的塑性区半径差别稍大.相对塑性区半径与地质强度指标都呈负乘幂函数关系,随着支护力的增大,塑性区半径随着岩体质量等级的升高而下降的趋势逐渐变缓.建立的相对塑性区半径随地质强度指标和支护力变化的二元非线性回归数学模型简明,使支护力连续变化,提高了工程实用性.结论 在岩体质量较差情况下,锚杆深度取1.8～3.0倍硐半径为宜.     

Theoretical analysis of a new segmented anchoring style in weakly cemented soft surrounding rock

According to the tensile failure of rock bolt in weakly cemented soft rock, this paper presents a new segmented anchoring style in order to weaken the cumulative effect of anchoring force associated with the large deformation. Firstly, a segmented mechanical model was established in which free and anchoring section of rock bolt were respectively arranged in different deformation zones. Then, stress and displacement in elastic non-anchoring zone, elastic anchoring zone, elastic sticking zone, softening sticking zone and broken zone were derived respectively based on neural theory and tri-linear strain softening constitutive model of soft rock. Results show that the anchoring effect can be characterized by a supporting parameter b. With its increase, the peak value of tangential stress gradually moves to the roadway wall, and the radial stress significantly increases, which means the decrease of equivalent plastic zone and improvement of confining effect provided by anchorage body. When b increases to 0.72, the equivalent plastic zone disappears, and stresses tend to be the elastic solutions. In addition, the anchoring effect on the displacement of surrounding rock can be quantified by a normalization factor δ.     

基体界面屈服强度和残余应力失配对界面裂纹扩展的影响

对基体界面屈服强度和残余应力失配情况下的界面裂纹扩展机制进行了力学理论分析,并通过位错与裂纹的关系理论计算了界面裂纹尖端塑性区尺寸。结果表明:当界面裂纹由低强度区向高强度区扩展时,高强度区的残余压应力和屈服强度减少了裂纹尖端的塑性区长度和裂纹尖端张开位移,从而起到了抑制界面裂纹扩展的作用。