点荷载下岩石记忆效应的声发射数值模拟试验研究

利用岩石破裂过程数值模拟软件RFPA对点荷载下岩石的声发射特征进行数值模拟,通过对试验循环声发射事件数强度百分比、声发射累积数的应变百分比及声发射空间分布进行对比,发现点荷载下岩石不仅对先期应力具有很好的记忆效应,对先期最大线应变也有明显的记忆能力.     

Physical simulation of rock burst induced by stress waves

The behavior of stress wave propagation in rock walls and the process of rock bursts were simulated by application tests of material similar to rock. Results show that 1) the attenuation characteristics of stress waves were related to the material proper-ties, stress waves attenuate more quickly in soft material and 2) when the explosion load was applied at the top of the roadway, the number and the length of the cracks increased with a decrease in the distance between the explosive point and roof of the roadway.When the distance was 280 mm, only some chips appeared near the source, when the distance was 210 mm, some small cracks started to appear near the road-rib and when the distance was reduced to 140 mm, larger cracks appeared at the road-rib. It can be concluded that, under a given stress the number of cracks is closely related to the intensity of stress waves. The cracks in the sur-rounding rock can be reduced by controlling the intensity of the stress waves and rock bursts can be avoided to some extent by pre-venting the formation of layered crack structures. A new experimental approach has been provided for studying rock bursts by using physical simulation.     

破碎围岩浅埋偏压隧道衬砌荷载的计算方法

隧道洞口大都会面临围岩破碎、浅埋和偏压等不良地质地形情况,现行规范只给出了偏压隧道衬砌荷载的计算方法。对于破碎围岩浅埋偏压隧道,根据现场情况及实测的衬砌受力和变形特征表明其与规范假定不同,不宜直接利用规范方法。通过工程实例分析及隧道三维数值分析结果提出了浅埋偏压隧道破碎围岩的破坏模式,即隧道开挖后深埋侧岩体滑塌下落挤压支护结构使其向外侧变形,从而外侧支护受到被动土压力。根据提出的破坏模式,将隧道开挖后围岩主要分为滑塌区和被动区,在此基础上利用极限平衡法推导出了衬砌荷载的计算公式。将计算得到的结果与现场实测值对比发现,对于围岩极其破碎且存在较严重偏压的浅埋隧道工程,提出的计算方法比采用规范方法更接近实际情况。     

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.     

主应力方向对隧道稳定性影响规律的研究

采用模型实验方法和数值模拟方法探究了马蹄形隧道在不同方向主应力作用下围岩从初始损伤到完全破坏的全过程,归纳分析马蹄形隧道在不同方向主应力作用下的破坏规律。数值模拟方法采用最大拉应变准则,计算出隧道周边各点的相当应力,与模型实验结果吻合较好。结果表明,马蹄形隧道裂纹的产生和扩展大致沿主应力方向,马蹄形隧道围岩的破坏模式随主应力方向而改变。破坏应力的最大值出现在主应力与隧道成60°左右时,破坏应力的最小值则出现在主应力与隧道成45°左右和90°左右时,且45°左右方向的破坏应力与90°左右方向的破坏应力基本相同。     

Numerical Analysis of Effect of Water on Explosive Wave Propagation in Tunnels and Surrounding Rock

Based on the application of practical engineering, propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The effect of water on the damage of the concrete slab in a tunnel is compared with damage inflicted without water. The numerical simulation illustrates that water plays an important role in the evolution of damage of the concrete slab in a mine tunnel. In the presence of water in the rock the concrete slab is damaged more severely than without water in rock. The effect of water location in the rock is also considered. It is found that the concrete slab in the tunnel shows various degrees of damage as a function of the different locations of water. Attenuation laws of stress waves over time-space in rock with water are also obtained. Numerical results indicate that, under blast loading, there are three zones in the rock： a crushed zone nearby the explosive charge, a damaged zone and an elastic zone. The conclusions of numerical analysis may provide references for blasting designs and structure protection.     

深部复合顶板巷道变形破坏机理研究

高应力下软弱复合顶板的持续塑性变形破坏,是深矿井巷道支护与维护的难点之一.分析了车集煤矿2405工作面区段运输平巷和区段回风平巷的围岩结构和岩性特征,构建了该类巷道复合顶板的力学模型,导出了该模型的力学变形方程.对巷道顶板变形破坏机理进行了深入分析,认为当巷道顶板岩层所受轴向压力大于岩梁达到屈服时的临界压力0.8倍时,巷道变形(下沉)明显增大,严重时产生冒顶.提出了同类巷道掘进过程中围岩控制的关键措施.     

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.     

基于3D打印模型试验的含结构面异形隧洞的变形破坏研究

隧洞交叉段稳定性受围岩结构面影响较大,物理模型试验是研究结构面影响机制的有效手段.针对模型难以制备的技术瓶颈,采用3D打印增减材技术制备含非贯通结构面的异形隧洞模型.基于数字图像相关技术与内窥摄像头观测模型在单轴加载下的破坏过程,评估打印路径对隧洞模型破坏模式的影响,并研究结构面倾角对异形隧洞破坏机制的影响规律.结果 ...     

松散地层隧道进洞段管棚注浆加固效应分析

依托江西萍莲高速莲花隧道,建立考虑松散地层隧道进洞段管棚注浆加固效应的隧道开挖三维有限元计算模型,实现不同管棚注浆加固参数对隧道开挖稳定性影响的定量分析,在数值计算过程中研究注浆加固区力学参数(弹性模量、黏聚力)、管棚间距、注浆半径等因素对隧道稳定性的影响,并将研究成果应用于依托工程中,验证数值计算结果的正确性。研究结果表明:在隧道进洞段,隧道拱顶区域与掌子面前下方区域存在塑性区,上述2个区域为隧道进洞开挖过程中最易失稳的区域;管棚注浆加固可有效限制围岩变形,降低围岩体积应变,且管棚注浆加固区可有效隔离拱顶区域的围岩塑性区,有利于保证隧道拱顶安全;在整个管棚注浆加固长度内,管棚最大沉降量出现在隧道开挖掌子面附近;管棚最大沉降量的绝对值与注浆加固区弹性模量及注浆半径负相关,而与管棚间距正相关,但管棚间距对管棚最大沉降量的影响程度相比其他2个因素小。     

Numerical Simulation of Rock Burst in Circular Tunnels Under Unloading Conditions

Rock burst in a circular tunnel under high in-situ stress conditions was investigated with a numerical method coupled the rock failure process theory (RFPA) and discontinuous deformation theory (DDA).Some numerical tests were carraied out to investigate the failuer patterns of circular tunnel under unloading conditions.Compared the results under loading conditions, the shapes of failure zones are more regular under the unloading conditions.The failure patterns in the same type of rock mass are clearly different because of non-homogeneity of the rock material.The extension of cracks shows some predictability with an increasing of in-situ stress.When the homogeneity index of rocks (m) is either relatively high or low and lateral pressure coefficients (λ) is high, the number of regular shear slide cracks decreases and the probability of a rock burst also becomes lower.Our numerical simulation results show that the stability of surface rock and the natural bedding stratification of rock material greatly affect rock bursts.Installing bolts with due diligence and suitably can effectively prevent rock bursts.However, it is not effective to control rock bursts by releasing the strain energy with normal pre-boreholes.     

松散地层隧道进洞段管棚注浆加固效应分析

依托江西萍莲高速莲花隧道,建立考虑松散地层隧道进洞段管棚注浆加固效应的隧道开挖三维有限元计算模型,实现不同管棚注浆加固参数对隧道开挖稳定性影响的定量分析,在数值计算过程中研究注浆加固区力学参数(弹性模量、黏聚力)、管棚间距、注浆半径等因素对隧道稳定性的影响,并将研究成果应用于依托工程中,验证数值计算结果的正确性。研究结果表明:在隧道进洞段,隧道拱顶区域与掌子面前下方区域存在塑性区,上述2个区域为隧道进洞开挖过程中最易失稳的区域;管棚注浆加固可有效限制围岩变形,降低围岩体积应变,且管棚注浆加固区可有效隔离拱顶区域的围岩塑性区,有利于保证隧道拱顶安全;在整个管棚注浆加固长度内,管棚最大沉降量出现在隧道开挖掌子面附近;管棚最大沉降量的绝对值与注浆加固区弹性模量及注浆半径负相关,而与管棚间距正相关,但管棚间距对管棚最大沉降量的影响程度相比其他2个因素小。     

公路隧道应力释放率对软弱围岩稳定性影响

近年来,由于新奥法广泛地运用于地下工程的施工过程中,围岩与支护结构之间的相互作用以及支护时机受到越来越多的关注。中条山隧道洞口段软弱围岩开挖步序多、工序及应力变化复杂,尤其是核心土解除后和二衬施工前安全风险大。本文采用有限差分软件对该隧道洞口段施工过程进行三维数值模拟,研究了洞周位移及支护结构在不同应力释放率下的力学响应,重点分析了典型断面处洞周围岩及支护结构的位移和受力情况,以及洞周位移随施工过程的动态变化规律。研究结果表明：对于软弱围岩公路隧道,应力释放率越大,围岩的塑性区发展范围越大,洞周位移越大;开挖过程中,拱顶沉降受到的持续性扰动较大;待二次衬砌施作后,仰拱隆起和收敛位移趋于稳定。     

隧洞破碎带围岩失稳破坏模式及控制措施研究

为了解决在隧洞开挖过程中遇到节理带、断层等软弱破碎岩带时,发生大变形、塌方等围岩失稳破坏等问题,需提前或及时做好围岩支护措施,以确保洞室围岩的稳定及施工安全。本文以长河坝水电站泄洪洞工程为研究对象,通过对现场勘测资料、隧洞开挖施工方案及工程地质条件等的综合分析,确定了软弱破碎带围岩稳定的主要影响因素,提出了隧洞破碎带围岩的典型失稳破坏模式。针对隧洞破碎带处围岩的潜在失稳问题,综合采用超前支护、开挖后及时进行喷锚+钢支撑+锚筋束联合支护,并通过有限元手段对隧洞围岩支护方案的加固效果进行了分析。有限元计算结果表明,隧洞破碎带处经及时加强支护后,围岩变形得到有效地控制,避免了洞室围岩失稳破坏现象的发生;现场监测数据及实施效果也表明及时加强支护措施对围岩稳定控制的有效性。     

不同大变形等级下层理角度对层状软岩隧道的影响

为探究不同大变形等级下层理角度对层状软岩隧道的影响,依托九绵高速全线软岩大变形隧道,通过岩石力学试验确定遍布节理模型参数,基于数值模拟,探究不同软岩大变形等级（轻微、中等、强烈）下层理角度对层状软岩大变形隧道围岩及支护体系受力变形的影响,并通过现场统计的层理角度与大变形情况对数值模拟结果进行验证。结果表明：1）层理小角度（0°、15°）与大角度（90°）围岩变形、支护结构受力变形较大,随着大变形等级的增大,层理角度引起的围岩支护变化效果越明显。2）随着层理角度的增大,围岩变形从拱底逐渐转移到右拱腰。围岩变形主要发生在隧道轮廓与层理面相切位置,其中拱底及左拱脚对层理角度变化较敏感。3）初支应力偏向及节理塑性区大致与层理弱面法向一致,随着层理角度的增大,节理的剪切塑性区由拱顶、拱底转移到左拱脚、右拱肩,最终偏移到左右拱腰上下位置;相比初支压应力,初支拉应力对层理角度更敏感,垂直节理增大了张拉剪切破坏塑性区贯通的风险,但剪切破坏塑性区半径反而有可能减小。4）现场的统计规律表现为小角度与大角度大变形等级较高,层理角度为60°以下时,岩层破坏发生在拱腰及拱肩处,随着层理角度的增大,有向拱肩发展的趋势,大角度层理时岩层破坏主要发生在拱腰处。     

增湿条件下膨胀土隧道围岩的稳定性

增湿条件下,膨胀土的强度会降低并产生膨胀力,在两者的共同作用下,膨胀土隧道围岩稳定性会严重降低,有必要研究增湿条件下膨胀土隧道围岩的变形和衬砌受力。采用室内试验和数值模拟的方法对膨胀土隧道围岩稳定性进行研究,对不同含水率的重塑膨胀土进行剪切试验,得出摩擦角、黏聚力与含水率的拟合关系式,运用ABAQUS有限元软件对膨胀土隧道开挖过程进行仿真分析,并利用温度场模块模拟隧道围岩增湿膨胀,得出隧道增湿前后应力与位移的变化规律,同时设计正交试验,分析各因素对膨胀土浅埋隧道稳定性的影响。结果表明：围岩增湿之后,围岩拱腰处的应力值增加明显,拱顶和拱底处应力值减小;衬砌的拱底处纵向位移值增加,拱顶处纵向位移值减小。通过设计正交试验,采用极差和方差分析得到对膨胀土浅埋隧道围岩稳定性影响最大的因素为增湿强度,其次为覆跨比、膨胀厚度和膨胀系数。     

煤矿开采诱发地震的成因及预防

由于围岩破坏过程的复杂性,煤矿开采诱发地震成因比天然地震成因更为复杂.结合徐州某煤矿矿震灾害实例,分析煤矿开采诱发地震的成因及矿震波的特性,提出防治矿震危害的措施;计算冒落岩石的重力势能、顶板岩石冒落时冲击气浪的能量和矿震震级,并将计算的震级与地震台网测定的结果进行比较后发现误差较小,即相对误差为3.7%.研究结果表明：矿震波形呈现周期大、衰减快以及前后无关联的特征;虽然矿震可以分为顶板冒落、顶板开裂、矿柱冲击和断层剪切等类型,但实际上大多是多种类型的复合,围岩应力分布复杂;矿震的过程就是能量的释放过程.矿震成因非常复杂,如何有效利用数值预测技术预测矿震还有待进一步研究和探讨.     

Control technology and coordination deformation mechanism of rise entry group with high ground stress

Based on engineering practices of Wuyang Coal Mine, we carried out X-ray diffract researches on No. 3 coal; and the rocks of its roof and floor by XRD meter, and simulated the interactive effect of the surrounding rock deformation by FLAC^2D5.0 numerical simulation software under the condition of different tunneling method of multimine roadway in parallel. The internal structures of the surrounding rocks of 76 belt roadway were monitored by borehole observation instruments; and then, we analyzed the reason of failure and deformation of surrounding rocks of several rise entry, and proposed the technical measures for controlling interactive effect of several rise entry surrounding rock deformation at last. For the thickness seam rise roadway, two conclusions were drawn: one is that the co-deformation among roadway groups mainly reflect on that both shear failure and deformation in coal pillar among roadways have decreased the width of pillar core region and clamping action of coal pillar to roof strata, increased the actual span of roof strata, intensified the flexural failure of roof strata and prized the bed separation of roof deep rock strata. The other conclusion is that the factors controlling the interactive deformation among roadways is obvious when appropriate re-adjustment in construction sequence of the tunneling of multimine parallel roadways because the construction sequence among roadways also has great effects on deformation of the surrounding rock in roadway.     

二道垭隧道开挖与支护的数值模拟分析

大量工程实践表明，岩体工程开挖后的应力调整和变形并不是瞬时完成，本文采用大型有限元工程模拟分析软件ABAQUS，模拟二道垭隧道的开挖与支护过程，研究隧道开挖后考虑不同的应力释放比例后再支护时，围岩的变形及锚杆的受力情况．计算结果表明：对于松软岩层来说，考虑应力释放后再支护的计算结果更好地反映工程围岩的变形和破坏特性．     

二道垭隧道开挖与支护的数值模拟分析

大量工程实践表明，岩体工程开挖后的应力调整和变形并不是瞬时完成，本文采用大型有限元工程模拟分析软件ABAQUS，模拟二道垭隧道的开挖与支护过程，研究隧道开挖后考虑不同的应力释放比例后再支护时，围岩的变形及锚杆的受力情况. 计算结果表明：对于松软岩层来说，考虑应力释放后再支护的计算结果更好地反映工程围岩的变形和破坏特性.