基于复变理论的城门洞型隧洞围岩黏弹性位移解析解（研究生论坛）

围岩蠕变特性是影响隧洞长期稳定性的主要因素,目前对黏弹性位移仅得到圆形、椭圆形和矩形等简单边界的解析表达式,而对城门洞型隧洞,则尚未提出较精确的黏弹性位移计算式。基于任意边界的围岩弹性位移的计算过程,运用复变函数理论,根据实际情况简化计算模型,推导了城门洞型隧洞围岩边界位移的弹性解析解,再根据弹性-黏弹性对应原理,通过Laplace变换及其逆变换进一步得到了城门洞型隧洞边界位移的黏弹性解析解。结合某软岩隧洞工程,开展解析解、弹性有限元及FLAC3D流变分析,计算表明：三种计算方法洞室边界黏弹性变形规律基本相似,初始弹性变形吻合较好,且黏性变形的演变规律与数值分析及现场实测结果基本一致,表明应用文中方法的实用性和可靠性。     

A new analytical solution for calculation the displacement and shear stress of fully grouted rock bolts and numerical verifications

In presence of difficult conditions in coal mining roadways, an adequate stabilization of the excavation boundary is required to ensure a safe progress of the construction. The stabilization of the roadways can be improved by fully grouted rock bolt, offering properties optimal to the purpose and versatility in use. Investigations of load transfer between the bolt and grout indicate that the bolt profile shape and spacing play an important role in improving the shear strength between the bolt and the surrounding strata. This study proposes a new analytical solution for calculation displacement and shear stress in a fully encapsulated rock bolt in jointed rocks. The main characteristics of the analytical solution consider the bolt profile and jump plane under pull test conditions. The performance of the proposed analytical solution, for three types of different bolt profile configurations, is validated by ANSYS software. The results show there is a good agreement between analytical and numerical methods. Studies indicate that the rate of displacement and shear stress from the bolt to the rock exponentially decayed. This exponential reduction in displacement and shear stress are dependent on the bolt characteristics such as: rib height, rib spacing, rib width and grout thickness, material and joint properties.     

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.     

弹性拉拔中锚杆轴力和剪力分布力学计算

通过构建平面和三维力学模型,推导了弹性状态下沿杆长方向轴力和黏结剪应力的分布函数,提出了锚杆剪应力衰减系数的概念,并给出了力学算式;对比分析了围岩为砂岩和煤体时,水泥锚固和树脂锚固两种情况下,锚杆轴力和剪力的衰减特征.结果表明：软岩锚固中轴力和剪力为全长分布型,硬岩0.8-1.0m左右即衰减为拉拔力的5%,黏结剪应力的主要作用范围为0-0.5m,在0.4-0.5m处衰减为0.06MPa左右.     

冻结红层软岩的蠕变特性研究

为研究第三系红层软岩在低温下的蠕变特性。对冻结红层进行单轴蠕变试验,试验结果表明,在应力水平较低时,软岩只存在衰减蠕变,随着应力水平的增大,当超过流变长期强度时,出现了非稳定蠕变;同时,随着温度的降低,软岩的瞬时应变量和蠕变量都会明显减少,而长期强度则有较大幅度的增长,说明温度对软岩及冻结壁的流变性质影响十分显著。引入与时间和应力相关的非线性黏滞系数和时间开关函数,对西原模型进行改进,得到了可以描述加速蠕变的非线性流变本构模型,通过试验数据对冻结红层软岩的参数进行了辨识。将流变模型嵌入到abaqus有限元程序,并对井筒开挖进行数值模拟,获得冻结壁最大位移与时间曲线,通过与实测值进行比较,两者较为吻合。可见,建立的流变模型能够很好的描述冻结红层软岩的蠕变规律。     

坝区岩体蠕变参数反演与边坡开挖流变计算分析

软弱岩体是影响边坡安全稳定的重要因素,为有效反映大岗山坝区辉绿岩脉和断层破碎带等软弱岩体的蠕变变形特性,根据大岗山坝区现场压缩蠕变试验资料和推导的基于广义开尔文模型的刚性承压板边缘岩体的粘弹性变形计算公式,采用优化反演法计算得到坝区软弱岩体的蠕变力学参数,建立了大岗山水电站坝区边坡开挖卸荷的三维流变计算分析模型,使用FLAC3D软件详细分析了边坡分步开挖过程中坝肩坝基岩体的变形特性和软弱岩体的蠕变力学效应,获得了对工程设计和施工具有指导意义的建议和结论.     

大岗山水电站坝区辉绿岩流变特性的三轴试验研究

为解决大岗山水电站坝基的辉绿岩的流变力学问题,利用RLW-1000三轴流变仪进行了不同应力路径下的三轴流变试验,得到了各工况下的应力-应变-时间曲线。结果表明：辉绿岩是典型的硬脆性岩石,存在明显的流变门槛值,破坏时表现为突发性的脆性破裂。在破裂应力水平下表现出减速蠕变、等速蠕变和加速蠕变,减速蠕变和加速蠕变历时都十分短暂。临近破裂时的横向蠕变速率均不同程度的大于轴向,这是导致岩石扩容的主要原因。由于流变过程中损伤不断发展,导致岩石整体强度下降,因此流变破坏强度普遍低于常规三轴压缩试验瞬时破坏强度。辉绿岩存在一定的蚀变现象,蚀变矿物呈细鳞片状集合体。由于蚀变带的存在,使得岩块的强度受到影响,岩石破裂极易发生在结晶程度较差的矿物颗粒部位或胶结程度较差的两种矿物接触部位。     

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.     

An Estimation Method of Stress in Soft Rock Based on In-situ Measured Stress in Hard Rock

The law of variation of deep rock stress in gravitational and tectonic stress fields is analyzed based on the Hoek-Brown strength criterion. In the gravitational stress field, the rocks in the shallow area are in an elastic state and the deep, relatively soft rock may be in a plastic state. However, in the tectonic stress field, the relatively soft rock in the shallow area is in a plastic state and the deep rock in an elastic state. A method is proposed to estimate stress values in coal and soft rock based on in-situ measurements of hard rock. Our estimation method relates to the type of stress field and stress state. The equations of rock stress in various stress states are presented for the elastic, plastic and critical states. The critical state is a special stress state, which indicates the conversion of the elastic to the plastic state in the gravitational stress field and the conversion of the plastic to the elastic state in the tectonic stress field. Two cases studies show that the estimation method is feasible.     

软土流变特性试验研究

根据室内三轴流变试验的结果,研究了北京地区粉质粘土的流变特性。结果表明,该类软土具有较明显的变形时效性及其在不同应力水平下的蠕变特性。通过分析蠕变曲线的规律,选择了广义开尔文五单元理论模型和时间硬化经验蠕变公式来描述软土的流变特性,并达到了良好的精度,建立了适合北京地区典型软土的流变理论模型和经验模型。     

高应力软岩隧道施工的时空效应分析

以湖南某高应力软岩隧道为背景,应用有限元软件ABAQUS对其施工的时空效应进行了分析,并对其影响范围及大小进行了研究,结果表明：高应力软岩隧道围岩稳定很大程度上受到隧道的＂空间效应＂及＂时间效应＂的影响,同时指出在施工时应尽早施加初期支护提高围岩自承能力,在围岩变形趋于稳定时施加二次支护坚决抑制软岩的流变所引起的大变形.     

软土的等效时间线剪切流变模型

为反映软土剪切流变的非线性特性,建立剪切流变模型,修正了Singh-Mitchell提出的指数型剪切蠕变经验公式,使之适用于低修正应力水平工况.根据黏塑性剪应变-耗散剪应力-等效时间之间的关系方程推导出黏塑性剪应变速率与剪应力和黏塑性剪应变之间的函数表达式.把该表达式和剪切弹性模型相结合,建立了剪切弹黏塑性模型.以此模型为基础,不但获得了有效围压恒定时单级和多级荷载作用下的剪切流变解析解,而且还获得了有效围压和剪应力均随时间变化时的剪切流变积分解答.结果表明,流变模型能够较好地定量模拟三轴固结排水试验中多级加载作用下的剪切蠕变发展过程,合理地反映剪应变随修正应力水平(或剪应力)、有效围压和持续时间等影响因素变化的流变规律.     

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.     

对地基应力解除法进行建筑物纠偏数值模拟

为研究对建筑物进行纠偏，提出了土体的一种非线性弹—粘弹性流变本构模型，并将模型成功运用于软粘土纠偏实践中，用有限元法对地基应力解除法纠偏建筑物的全过程进行了数值模拟，并对施工过程中地基应力水平场和位移场的变化转移、沉降速率随时间的变化规律及计算范围内地面的沉降量等进行了分析；结果表明：软土的流变特性对纠偏的影响不可忽略；考虑土体的流变能够较好地指导建筑物的纠偏实践。     

基于三维损伤流变理论下某调压井群围岩时效稳定性研究

拟建的某水电站调压井区域围岩岩性为石英云母片岩,勘探及室内试验发现其岩体属于片理构造发育明显的软岩,具有较典型的横观各向同性流变特征。由于区域地应力水平较高,工程施工期及运行期围岩流变现象可能显著影响岩体稳定性及衬砌结构特性。本文在全面反映区域地质构造、调压井结构形式及地应力场的基础上,建立了三维数值计算模型,同时考虑施工时序及支护衬砌措施,应用根据室内试验及现场监测资料建立的横观各向同性岩体粘弹塑性损伤本构模型,采用FLAC3D软件研究了调压井群施工期和运行期围岩稳定性及衬砌结构安全性。结果表明：施工开挖过程中围岩在流变效应的显著影响下,其变形量随时间有所增加,及时喷锚支护对围岩变形的限制作用显著,开挖完成后500d后围岩位移趋于收敛;开挖完成后围岩整体处于受压状态,施作二次衬砌有利于围岩应力场均匀化重新分布;运行期调压井衬砌变形量值增长速率随时间逐渐减小,其中2年内变形量约占长期（50年）变形量的54%,调压井围岩及衬砌结构运行1年后应力水平基本趋于稳定,运行期内调压井围岩应力水平变化幅度很小。     

土的应力历史对软粘土地基深基坑性状的影响

提出了一种在分步开挖的深基坑工程中计算受超固结影响的饱和粘土强度的方法,得出能同时反映开挖应力路径和应力历史的饱和粘土非线性应力应变关系。通过典型算例的有限元法分析,研究了软粘土深基坑性状及土的应力历史对其性状的影响。     

岩石流变的一种非线性黏弹塑性流变模型研究

将黏滞系数视为非定常量,建立黏滞系数的非线性函数关系,提出一种能描述岩石蠕变全过程的非线性流变力学模型,且在一定条件下模型可蜕变为Burgers模型或西原正夫模型。推导了岩石在常应力和常应变条件下的流变方程;研究了岩石的非线性蠕变特性和松弛特性。对不同应力条件下的岩石蠕变试验结果进行拟合,并将本文的非线性岩石流变力学模型与试验结果进行比较。结果表明,试验曲线与理论曲线较吻合,从而证明了本模型的正确性与合理性。     

营口地区软土流变模型参数及流变特性研究

根据辽宁营口地区淤泥质粉质粘土的流变试验,对流变模型参数及流变特性的变化规律进行探讨.研究表明:运用模型理论建立的流变模型的线性粘弹性参数在低应力水平下是惟一的,但非线性粘弹性参数不惟一,并随应力水平的变化而变化,而粘塑性参数的大小决定了应力应变等时曲线的形状.此外,流变模型的参数随试验条件的不同而变化.基于营口地区淤泥质粉质粘土的粘弹性及粘塑性流变特性,指出二者随时间和应力水平的变化表现出不同的流变特性.     

茅口灰岩单轴压缩条件下的流变特性试验研究

取重庆北碚车站隧道茅口灰岩,根据现场岩层覆盖厚度及其茅口灰岩容重,取单轴压缩应力为6 MPa,采用MTS815多功能岩石试验机对岩样进行24 h单轴压缩蠕变试验,得到岩石轴向应变-时间曲线。分析岩石应变-时间曲线,发现茅口灰岩具有弹性-弹粘性之流变特性,与Poyting-Thomson model相似。用Origin软件对流变试验数据用Poyting-Thomson model方程进行拟合,得到低应力下流变拟合曲线,该拟合曲线能较好反应试验数据。因此,Poyting-Thomson model能较好反应茅口灰岩流变特性。最后求出了茅口灰岩低应力作用下流变模型各项参数。     

Distribution of ground stress on Puhe Coal Mine

Puhe Coal Mine is a typical Tertiary coal in Shenbei mining area. With an increase in mining depth, tectonic stress field becomes more complex, leading to increased deformation and failure of the soft rock roadway. Stress becomes an important factor of mine safety and stability. This paper analyzes the distribution of the regional tectonic field, and determines the distribution of situ stress measurement through measuring the ground stress field in the main mining area level of Puhe Coal Mine using stress relief method. The acquired in situ stress data at different locations and depths provide a reference for the rational arrangement of the stop and mine roadway supporting design, which are of great significance for the efficient safety production of the mine.