爆破作用下顺层岩质边坡稳定的可靠性分析

基于可靠度理论建立顺层岩质边坡稳定的可靠性分析方法,获得顺层岩质边坡可靠指标和失稳概率的计算表达式。以某高切坡为例分析其稳定状态和失稳概率,并据此探讨不同粘聚力、内摩擦角、炸药量和爆心距条件下边坡失稳概率的变化规律。计算结果表明,粘聚力对边坡的失稳概率影响较大;随着内摩擦角的增加,边坡失稳概率近乎线性减小;当单孔药量从10 kg增大到160 kg后,失稳概率增幅97.10%;当爆心距小于20 m时,边坡的失稳概率减小的速度很快,而爆心距超过20 m后边坡失稳概率减小的幅度较小。考虑爆破振动的时效性,爆破荷载使边坡失稳概率增大49.61%,单次爆破振动的影响时间约6 s。     

Bearing mechanism of a tunnel-type anchorage in a railway suspension bridge

A tunnel-type anchorage(TTA) is one of the main components in suspension bridges: the bearing mechanism is a key problem. Investigating the deformation characteristics, development law, and failure phenomenon of a TTA under load can provide the theoretical basis for a robust design. Utilizing the TTA of the Jinsha River suspension bridge at Lijiang Shangri-La railway as a prototype, a laboratory model test of the TTA was carried out for three different contact conditions between the anchorage body and the surrounding rock. The stress and deformation distribution law of the anchorage body and its surrounding rock were studied, and the ultimate bearing capacity and failure mode of the TTA were analyzed. The test results show that the compressive stress level is highest at the rear part of the anchorage body. Moving away from the rear portion of the body, the stress decays in a negative exponential function. Based on the load transfer curve, the calculation formula for the shear stress on the contact surface between the anchorage body and the surrounding rock was derived, which shows that the distribution of the shear stress along the axial direction of the anchorage body is not uniform. The distance from the maximum value to the loading surface is approximately 1/3 of the length of the anchorage body, and the stress decreases as the distance from the loading surface increases. Furthermore, the contact condition between the anchorage body and surrounding rock has a great influence on the bearing capacity of the TTA. The increase in the anti-skid tooth ridge and radial anchor bolt can improve the cooperative working capacity of the anchorage body and the surrounding rock, which is approximately 50% higher than that of the flat contact condition. The main function of the anchor bolt is to increase the overall rigidity of the TTA. The contact condition between the anchorage body and the surrounding rock will lead to a change in the failure mode of the TTA. With an increase in the degree of contact, the failure mode will change from shear sliding along the interface to trumpet-shaped inverted cone-shaped failure extending into the surrounding rock.     

二氧化碳爆破致裂激发干热岩储层作用效果

采用二氧化碳爆破致裂为激发干热岩储层提供了一种新的技术思路和途径。为了探究二氧化碳爆破致裂激发干热岩储层的作用效果, 开展了二氧化碳爆破致裂干热岩储层作用范围的数值模拟研究。考虑实际开采过程中钻井液对井壁附近干热岩储层的降温影响, 采用以温差为变量的拟合函数设置损伤区储层材料参数, 用洗井后井壁附近储层温度分布函数设置损伤区储层温度场, 并借助炸药爆破的相关理论、公式设置爆破荷载, 结合COMSOL软件模拟了二氧化碳爆破致裂激发干热岩储层的过程。结果表明, 二氧化碳爆破致裂干热岩过程中存在多次应力集中作用, 且在炮孔附近压应力集中造成压碎区, 压碎区外拉应力作用形成裂隙区; 储层的初始温度以及定压片厚度都会影响二氧化碳爆破致裂激发干热岩储层的作用效果, 其中初始温度对爆破压碎区范围影响较大, 对裂隙区范围影响较小, 定压片厚度改变对压碎区范围影响较小, 主要影响爆破裂隙区的分布。本研究成果可为干热岩地热能后续的开采利用提供理论支持和参考。      

土工格室加固风积沙路基不同深度动力响应试验研究

风积沙路基的处理一直是沙漠公路建设面临的难题, 土工格室加固方法可为沙漠公路建设提供一条新路径, 结合S21线(乌鲁木齐-阿勒泰)沙漠公路路基现场试验, 研究不同路基深度动力响应特征, 对土工格室加固风积沙性能探究具有重要的价值及意义。结果表明: ①测试车速对路基不同深度处动应力、动加速度和动速度的时程曲线波动性影响较大, 且提高车速时, 动速度峰值、动加速度峰值和动应力峰值都出现了明显的增加; ②随着路基层深度的不断增加, 动速度幅值、动加速度幅值和动应力幅值均呈现出逐渐衰减的趋势, 其中在土工格室加固风积沙层衰减幅度最大; ③沿路基横断面水平方向上, 动速度幅值、动加速度幅值和动应力幅值均呈指数型衰减的趋势, 距振动源水平距离为5 m时, 其幅值衰减至10%左右, 可将此水平范围作为工程设计参考值。      

地埋管换热影响岩土体传热因素及热影响范围分析

该文介绍了地埋管换热器传热模型,对影响地下岩土体传热的地埋管换热功率、持续时间、热泵机组运行的方式与模式、换热器规格、管外回填材料以及地质-水文地质条件等因素进行了探讨,认为周围岩土体热响应范围大小与换热功率大小和持续时间长短、管外回填材料和周围岩土体导热性能高低呈正相关性,热泵机组间歇运行方式有利于地温场的及时恢复,冬季制热夏季制冷模式能削弱单一负荷聚集产生的热影响程度,同等能条件下双U型De32地埋管较单U型De25地埋管热影响范围要大。由于地埋管换热器吸热或放热不平衡而引起的冷热量累积效应,渗流速度越大,热影响范围则越大。济南东部碎屑岩区某模拟夏季工况试验表明,其他条件相同的前提下,8 k W换热功率持续运行,以换热孔为中心,岩体温度响应速率和影响幅度与径向距离成负相关性,距离越近,响应速率和影响幅度越大,反之就越小;47天后,地埋管换热器热影响范围大于5m。     

Finite element analysis for blasting law of jointed rock mass

On the basis of Mises strength theory, rock models are built including vertical, horizontal and diagonal joints to simulate jointed rock mass under blasting load by using FEM. The dynamic procedures of jointed rock mass under blasting are quantified and the effective stress-time curves of typical elements are compared to analyze the barrier of joints to the stress wave. The blasting law was studied according to the process of computer simulation and the effect of blasting, and some suggestions were given for solving the problems of overbreak and underbreak.     

Dynamic response of a slope reinforced by double-row antisliding piles and pre-stressed anchor cables

Large-scale shaking table tests were conducted to study the dynamic response of a slope reinforced by double-row anti-sliding piles and prestressed anchor cables. The test results show that the reinforcement suppressed the acceleration amplification effectively. The axial force time histories are decomposed into a baseline part and a vibration part in this study. The baseline part of axial force well revealed the seismic slope stability, the peak vibration values of axial force of the anchor cables changed significantly in different area of the slope under seismic excitations. The peak lateral earth pressure acting on the back of the anti-sliding pile located at the slope toe was much larger than that acting on the back of the anti-sliding pile located at the slope waist. The test results indicate an obvious load sharing ratio difference between these two anti-slide piles, the load sharing ratio between the two anti-sliding piles located at the slope toe and the slope waist varied mainly in a range of 2-5. The anti-slide pile at the slope waist suppressed the horizontal displacement of the slope surface.     

Finite element ana lysis for blasting law of jointed rock mass

On the basis of Mises strength theory, rock models are built including vertical, horizontal and diagonal joints to simulate jointed rock mass under blasting load by using FEM. The dynamic procedures of jointed rock mass under blasting are quantified and the effective stress-time curves of typical elements are compared to analyze the barrier of joints to the stress wave. The blasting law was studied according to the process of computer simulation and the effect of blasting, and some suggestions were given for solving the problems of overbreak and underbreak.     

大奔流顺层岩质滑坡溃屈型破坏力学机制研究

溃屈型破坏是顺层岩质边坡一种常见的破坏模式。以大奔流顺层岩质滑坡为例，分析了其溃屈型破坏的形成机制，绿泥石片岩层面发育程度和层面抗剪强度及岩石破碎程度是大奔流滑坡发生的主要地质因素，爆破震动荷载和地下水作用是发生溃屈型破坏的主要诱发因素。基于弹性板梁稳定理论和能量平衡原理，建立了顺层岩质滑坡溃屈型破坏力学模型；通过力学分析，提出了综合考虑滑坡自重、地下水与震动荷载作用的顺层岩质滑坡溃屈段长度条件方程。以大奔流滑坡为实例进行了验算，计算结果和现场破坏特征基本一致，表明了该方法的可行性，为研究顺层岩质滑坡溃屈型破坏的力学机制提供了依据。      

Shaking table test of seismic responses of anchor cable and lattice beam reinforced slope

As a combined supporting structure,the anchor cable and lattice beam have a complex interaction with the slope body.In order to investigate the seismic behaviors of the slope reinforced by anchor cable and lattice beam,a largescale shaking table test was carried out on a slope model(geometric scale of 1:20)by applying recorded and artificial seismic waves with different amplitudes.The acceleration and displacement of the slope,the displacement of lattice beam and the axial force of anchor cable were obtained to study the interaction between the slope and the supporting structure.The test results show that:(1)the acceleration responses of the slope at different relative elevations display obvious nonlinear characteristics with increasing of the peak ground acceleration(PGA)of the inputted seismic waves,and the weak intercalated layer has a stronger effect on acceleration amplification at the upper part of the slope than that at the lower part of the slope;(2)the frequency component near the second dominant frequency is significantly magnified by the interaction between the slope and the supporting structure;(3)the anchor cables at the upper part of the slope have larger peak and residual axial forces than that at the lower part of the slope,and the prestress loss of the anchor cable first occurs at the top of the slope and then passes down;(4)the peak and residual displacements inside the slope and on the lattice beam increase with the increase of relative elevation.When the inputted PGA is not greater than 0.5 g,the combined effect of anchor cable and lattice beam is remarkable for stabilizing the middle and lower parts of the potential sliding body.The research results can provide a reference for the seismic design of such slope and the optimization of supporting structure.     

定向控制爆破技术在斜井掘进中的应用

文章论述在斜井掘进中采用定向控制爆破技术 ,利用最小抵抗线原理 ,即最小抵抗线方向是爆破作用和岩石移动的主导方向 ,使石渣向后抛掷 ,以充分利用耙斗装岩机工作 ,从而大大提高工作效率 ,降低工人的劳动强度。     

Time-dependent squeezing deformation mechanism of tunnels in layered soft-rock stratum under high geo-stress

Large squeezing deformation of layered soft rock tunnel under high geo-stress has a significant time-dependent deformation behavior. In this paper, we studied the deformation mechanism during the construction period of deep-buried softrock tunnel by means of a combination of field observations and a numerical method. First, a new classification criterion for large deformations based on the power exponent variation law between the deformation and the strength-stress ratio is proposed. Then, the initial damage tensor reflecting the bedding plane(joint) distribution and an equivalent damage evolution equation derived from the viscoplastic strain are introduced based on the geometric research method, i.e., a new rheological damage model(RDL model) of layered soft rock is established consisting of elastic, viscous, viscoelastic, viscoplastic and plastic elements. A field test was conducted on the Maoxian tunnel in Sichuan province, southwestern China, which is in broken phyllite(layered soft rock) under high geo-stress. The tunnel has experienced large deformation due to serious squeezing pressure, thus we adopted double primary support method to overcome the supporting structure failure problems. The rheological parameters of phyllite in the Maoxian tunnel were recognized by using SA-PSO optimization, and the RDL model does a good job in describing the time-dependent deformation behavior of a layered soft-rock tunnel under high geo-stress. Thus, the RDL model was used to investigate the supporting effect and bearing mechanism of the double primary support method. Compared with the single primary support method, the surrounding rock pressure, secondary lining force, surrounding rock deformation, and the depth of the damage to the rock mass was reduced by 40%-60% after the double primary support method was used.     

Interaction analyses between tunnel and landslide in mountain area

This paper focuses on the analytical derivation and the numerical simulation analyses to predict the interaction influences between a landslide and a new tunnel in mountain areas. Based on the slip-line theory, the disturbance range induced by tunneling and the minimum safe distance between the tunnel vault and the sliding belt are obtained in consideration of the mechanical analyses of relaxed rocks over the tunnel opening. The influence factors for the minimum safe crossing distance are conducted, including the tunnel radius, the friction angle of surrounding rocks, the inclination angle of sliding belt, and the friction coefficient of surrounding rocks. Secondly, taking account of the compressive zone and relaxed rocks caused by tunneling, the Sarma method is employed to calculate the safety factor of landslide. Finally, the analytical solutions for interaction between the tunnel and the landslide are compared with a series of numerical simulations, considering the cases for different perpendicular distances between the tunnel vault and the sliding belt. Results show that the distance between the tunnel vault and the slip zone has significant influence on the rock stress and strain. For the case of the minimum crossing distance, a plastic zone in the landslide traversed by tunneling would be formed with rather large range, which seriously threatens the stability of landslide. This work demonstrates that the minimum safe crossing distance obtained from numerical simulation is in a good agreement with that calculated by the proposed analytical solutions.     

Supporting characteristics analysis of constant resistance bolts under coupled static-dynamic loading

To study the tensile mechanical properties of constant resistance bolts, the RFPA(Rock Failure Process Analysis) statics software is used to perform a uniaxial tensile test on a constant resistance bolt. The numerical test results show that the plastic strain value is 12 times the magnitude of the elastic strain. During plastic deformation, the fluctuation in the stress magnitude is relatively stable, indicating that the bolt has good constant resistance characteristics. The numerical test results are in good agreement with the laboratory test results of M.C. He, and the accuracy and reliability of the numerical test method are verified. Therefore, the RFPA software with coupled static-dynamic loading is further adopted to study the supporting effects of traditional bolts and constant resistance bolts under coupled staticdynamic loading. The numerical comparison of the test results show that the constant resistance bolts can effectively control the deformation amount and rate of the laneway surrounding rock, reduce the total and rate of increase in the accumulated acoustic emissions,decrease the stress on the units in the model and protect the stability of the laneway. This paper verifies that a constant resistance bolt has better impact resistance mechanical properties than those of a traditional bolt and provides an effective way to control rock burst and soft rock that is prone to large deformation damage.     

Variation of cavity gas pressure in slopes with weak intercalation under seismic load

This study discussed how cavity gas pressure affects the stability of rock mass with fractures under well controlled laboratory experiments. Suddenly-created void space created and the induced gas pressures have been the focus of active researches because they are associated with fast movement of large-scale landslides. A shaking table experiment was set up to mimic weak-intercalated rock slope under seismic loads. Excessive cavity gas pressure would be produced in weak spots upon a sudden vibration load. The drastically elevated gas pressure is believed to be responsible for the creation of cavities surrounding the tension fracture. With dissipation of the excessive cavity gas pressure, the fractures are in unbounded closed-state. This observation explains that the slope body would be split and loosened under several aftershocks, and with the expanding of the cracks, the slope failure eventually occurred. The research of the mechanism of cavity gas pressure could provide a novel insight into the formation mechanism of landslides under seismic load and has implications for the disaster prevention and control theory for the slope stability evaluation.     

Mass-front velocity of dry granular flows influenced by the angle of the slope to the runout plane and particle size gradation

The mass-front velocities of granular flows results from the joint action of particle size gradations and the underlying surfaces.However,because of the complexity of friction during flow movement,details such as the slope-toe impedance effects and momentum-transfer mechanisms have not been completely explained by theoretical analyses,numerical simulations,or field investigations.To study the mass-front velocity of dry granular flows influenced by the angle of the slope to the runout plane and particle size gradations we conducted model experiments that recorded the motion of rapid and long-runout rockslides or avalanches.Flume tests were conducted using slope angles of 25°,35°,45°,and 55° and three particle size gradations.The resulting mass-front motions consisted of three stages:acceleration,velocity maintenance,and deceleration.The existing methods of velocity prediction could not explain the slowing effect of the slope toe or the momentum-transfer steady velocity stage.When the slope angle increased from 25° to 55°,the mass-front velocities dropped significantly to between 44.4% and59.6% of the peak velocities and energy lossesincreased from 69.1% to 83.7% of the initial,respectively.The velocity maintenance stages occurred after the slope-toe and mass-front velocity fluctuations.During this stage,travel distances increased as the angles increased,but the average velocity was greatest at 45°.At a slope angle of 45°,as the median particle size increased,energy loss around the slope toe decreased,the efficiency of momentum transfer increased,and the distance of the velocity maintenance stage increased.We presented an improved average velocity formula for granular flow and a geometrical model of the energy along the flow line.     

在GPS伪距观测值中发现径速偏差

在 GPS伪距观测值中 ,发现存在着随测站和卫星距离变化而产生的系统偏差。经过严密、系统的计算 ,证明它是普遍存在的一种自然现象。它的主要部分和径向速度呈线性关系 ,在卫星向测站运动时伪距值偏大 ,在卫星背向测站运动时伪距值偏小 ,并呈负对称 ,偏差最大可达60 m。     

基于小波包变换的爆破震动信号能量分析方法

爆破震动效应测试和分析对于评估工程爆破安全和爆破效果非常重要,但对于采集到的爆破震动信号,在数据的处理和分析上还存在着诸多不足.在阐释小波变换基本原理的基础上,给出了爆破震动信号能量分析方法的理论解析,并结合应用实例,对爆破震动信号进行小波包能量分解.研究结果表明,基于小波包变换的能量分析方法可以较好地揭示信号在不同频带范围内的局部分布特征,从而为可靠地进行建(构)筑物爆破震动效应安全评估奠定理论基础.     

湖北随州ML4.7地震序列基础资料分析

依据随州三里岗ML4.7地震序列的地震监测和宏观调查所获得的基础资料,对此次地震序列的时空强特征及地震成因机理进行了分析。为使地震资料准确可靠,对混淆在序列中的爆破波形与地震波形进行了鉴别和剔除。结合这些基础资料和震源机制解结果。分析认为随州地震序列在成因上与该地区存在的北东和北西向两组断裂构造有关,但主发震构造是北西向断裂。     

湖北随州 ML4.7地震序列基础资料分析

依据随州三里岗ML4.7地震序列的地震监测和宏观调查所获得的基础资料,对此次地震序列的时空强特征及地震成因机理进行了分析。为使地震资料准确可靠,对混淆在序列中的爆破波形与地震波形进行了鉴别和剔除。结合这些基础资料和震源机制解结果。分析认为随州地震序列在成因上与该地区存在的北东和北西向两组断裂构造有关,但主发震构造是北西向断裂。